Response to Public Comment: 

National Pollutant Discharge Elimination System

Final Regulations to Establish Requirements for Cooling Water

Intake Structures at Existing Facilities and Amend Requirements

at Phase I Facilities

(40 CFR Parts 122 and 125)

Docket # EPA-HQ-OW-2008-0667

United States Environmental Protection Agency

1200 Pennsylvania Avenue N.W. 

Washington, DC 20460

May 19, 2014
Contents

Introduction

A. Methodology EPA Used to Sort and Code Public Comment Letters 

B. Locating Your Comments and EPA’s Response in the Final Document 

C. Duplicates, Attachments, Mass Mail Campaigns, and Keyword Searches

D. Disclaimer

Essay 1: General Support of the 316(b) Existing Facilities Rule ...............................................1 

Essay 2: General Opposition of the 316(b) Existing Facilities Rule ..........................................2 

Essay 4: Background Information about Commenter ...............................................................3 

Essay 5: Form Letters 1-14, Addressing Form Letters from the Alliance for the Great 

Lakes, Consumer Energy Alliance, Natural Resources Defense Council, 

Environmental Law and Policy Center, Sierra Club, National Wildlife Federation 

Action Fund, Food and Water Watch, Surfrider, Riverkeeper, and Other Unknown 

Organizations .............................................................................................................................5 

Essay 6: Comment Period, Schedule for Final Rule ...................................................................7 

EPA Provided an Adequate Opportunity to Comment ........................................................................... 7 

EPA Complied with EO 13563 .............................................................................................................. 8 

Essay 7: Seafood Processing, Offshore Oil and Gas, and LNG Terminals ............................10 

Essay 8: Purpose of the NODAs, Introduction ..........................................................................12 

Notice of Data Availability Related to Impingement Mortality Control Requirements ....................... 12 

Essay 10: Legal Authority, Purpose, and Background ............................................................13 

Essay 11: Proposed Amendments Related to the Phase I Rule ...............................................23 

Introduction .......................................................................................................................................... 23 

Phase I .................................................................................................................................................. 23 

Restoration for Phase II and Existing Facilities ................................................................................... 24 

Essay 12: New Data Used In Developing the Rule ....................................................................28 

Essay 13: Possible Differences between Generators and Manufacturers ...............................30 

Introduction .......................................................................................................................................... 30 

Background/History ............................................................................................................................. 31 

i 
Analysis of Information for the Existing Facilities Rule ...................................................................... 31 

Essay 14: Scope and Applicability ..............................................................................................38 

Introduction .......................................................................................................................................... 38 

General Applicability ........................................................................................................................... 38 

Clarify Applicability /Exclusions .................................................................................................. 38 

Point of Compliance ...................................................................................................................... 42 

Definition of Existing Facility ....................................................................................................... 45 

CWIS ............................................................................................................................................. 46 

Definition of Cooling Water Intake ...................................................................................................... 46 

Twenty-five (25) Percent Water Used for Cooling Purposes ........................................................ 46 

Scope of Exemption for Certain Waters ........................................................................................ 48 

Applicability to Point Source Discharges ...................................................................................... 51 

Least Energy Demanding Source of Water.................................................................................... 52 

Exemptions .................................................................................................................................... 52 

Public Water Systems .................................................................................................................... 53 

Waters of the United States ............................................................................................................ 55 

Independent Supplier ..................................................................................................................... 56 

Impoundments/Definition of CCRS ..................................................................................................... 57 

Closed-Cycle Cooling Definition is Too Narrow .......................................................................... 57 

Man-Made/Managed Impoundments ............................................................................................. 59 

Intermittent Flow in a Closed-Cycle Recirculating System ........................................................... 61 

Additional Suggestions on Requirements for Closed-Cycle Recirculating Systems ..................... 61 

Flow Thresholds ................................................................................................................................... 62 

Two MGD Applicability Threshold ............................................................................................... 62 

Use of AIF for Entrainment Characterization Study ..................................................................... 71 

Applicability of Rule to Offshore Oil and Gas Facilities, Seafood Processing Vessels or 

LNG Import Terminals .................................................................................................................. 73 

Definition and Applicability of New Unit ..................................................................................... 74 

Other Comments ............................................................................................................................ 77 

Essay 15: EPA’s Approach to Establishing Best Technology Available 316(b) 

Standards for New Units and Existing Units ........................................................................78 

Introduction .......................................................................................................................................... 78 

Overall Approach to BTA for Existing Units ....................................................................................... 78 

Approach to BTA for Entrainment at Existing Units/Facilities ........................................................... 79 

ii
Closed-Cycle Recirculating Systems ............................................................................................. 79 

Approach to BTA for Entrainment at New Units Constructed at Existing Facilities .................... 84 

Other Technologies for BTA for Entrainment at Existing Facilities ............................................. 84 

Approach to Impingement BTA at Existing Units/Facilities ............................................................... 87 

Role of Costs and Benefits in Determining BTA ................................................................................. 90 

Cost-Benefit/Benefits Must Justify the Costs/Maximize Net Benefits for the Final Rule ............. 90 

Consideration of Costs and Benefits on a Site-Specific Basis in Establishing Entrainment 

Controls - General .......................................................................................................................... 93 

Comments Specific to Cost ............................................................................................................ 95 

Benefits .......................................................................................................................................... 97 

Other Elements of BTA ........................................................................................................................ 98 

Variances ....................................................................................................................................... 98 

Availability and Flexibility of Rule Requirements ........................................................................ 99 

Essay 16: Requirements for Impingement and Entrainment ................................................105 

Introduction ........................................................................................................................................ 105 

Adverse Environmental Impact (AEI) ................................................................................................ 105 

Impingement Requirements................................................................................................................ 108 

Option Selection .......................................................................................................................... 110 

Compliance Alternatives .............................................................................................................. 111 

Entrainment Requirements ................................................................................................................. 120 

Technologies to Address Impingement and Entrainment ................................................................... 122 

Essay 16A: Impingement Mortality Performance Standards ...............................................125 

Introduction ........................................................................................................................................ 125 

Justification for the Proposed Standards ............................................................................................ 126 

Alternative Forms of the Standards .................................................................................................... 128 

Data Selection ..................................................................................................................................... 131 

Comment Summary ..................................................................................................................... 131 

EPA’s Reevaluation of Data and Response to Data Selection Comments .................................. 132 

Statistical Methodology ...................................................................................................................... 136 

Comment Summary ..................................................................................................................... 136 

EPA’s Reevaluation of the Statistical Methodology and Response to Statistical

Comments .................................................................................................................................... 137 

Achievability and Compliance Issues ................................................................................................ 140 

Public Review ..................................................................................................................................... 143 

iii
Essay 17: Intake Velocity ..........................................................................................................145 

Introduction ........................................................................................................................................ 145 

Background ........................................................................................................................................ 145 

Previous Comments on Intake Velocity....................................................................................... 145 

Previous Litigation on Intake Velocity ........................................................................................ 146 

EPA’s Response ................................................................................................................................. 146 

Availability/Feasibility ................................................................................................................ 146 

Derivation/Technical Framework ................................................................................................ 149 

Implementation ............................................................................................................................ 151 

Essay 17A: Closed-Cycle Recirculating Cooling .....................................................................154 

Introduction ........................................................................................................................................ 154 

Impoundments .................................................................................................................................... 154 

Cooling Towers .................................................................................................................................. 156 

Wet Cooling ................................................................................................................................. 156 

Dry Cooling ................................................................................................................................. 157 

Hybrids ......................................................................................................................................... 158 

Definition of Closed-Cycle Recirculating Cooling ............................................................................ 158 

Flow Reduction ............................................................................................................................ 158 

Cycles of Concentration ............................................................................................................... 160 

Intermittent Flow ......................................................................................................................... 162 

Emergency Flows ........................................................................................................................ 162 

Performance of CCRS ........................................................................................................................ 162 

Demonstration Status ................................................................................................................... 162 

Comparison to Other Technologies ............................................................................................. 163 

Evaporative Losses ...................................................................................................................... 163 

Alternative Sources of MakeUp Water ........................................................................................ 165 

Rejection of CCRS as BTA ................................................................................................................ 165 

Three Factors ............................................................................................................................... 165 

Cost and Affordability ................................................................................................................. 166 

Other Options Considered Based on CCRS ................................................................................. 166 

Essay 18: Impingement and Entrainment Technologies and Operational Measures .........168 

Introduction ........................................................................................................................................ 168 

Background ........................................................................................................................................ 168 

Overall Response: Introduction .......................................................................................................... 170 

iv
Impingement Mortality BTA Standard .............................................................................................. 170 

Entrainment BTA Standard ................................................................................................................ 171 

Specific Technologies Discussions .................................................................................................... 171 

Flow Reduction Technologies ..................................................................................................... 172 

Exclusion and Collection Technologies ....................................................................................... 176 

Avoidance/Behavioral Technologies ........................................................................................... 181 

Entrapment ......................................................................................................................................... 182 

Nuclear Facilities ................................................................................................................................ 184 

Essay 19: Regulatory Options ...................................................................................................187 

Introduction ........................................................................................................................................ 187 

General Response ............................................................................................................................... 187 

Factors for Supporting Site-Specific Entrainment and Rejecting a Uniform Standard Based 

On Closed-Cycle Cooling................................................................................................................... 189 

Land Availability ......................................................................................................................... 190 

Increased Air Emissions Could Be a Factor on a Local Basis ..................................................... 192 

Remaining Useful Plant Life Could Be a Factor on a Facility Basis ........................................... 193 

Energy Reliability is Not a Dispositive Factor in EPA’s Rejection of Closed-Cycle 

Cooling as BTA ........................................................................................................................... 196 

Other Factors ................................................................................................................................ 196 

Regulatory Options ............................................................................................................................. 198 

Technology Basis ......................................................................................................................... 198 

Proposal Option 1 ........................................................................................................................ 201 

Other Options Considered for Today’s Final Regulation ............................................................ 203 

Consideration of Costs and Benefits on a Site-specific Basis in Establishing Entrainment 

Mortality Controls, Including a Cost-Cost Test ................................................................................. 210 

Subcategorization ............................................................................................................................... 211 

Capacity Utilization Rating As a Basis for Different Standards, Peaking Units, Seasonal 

Operation and Other Related Comments ..................................................................................... 211 

Waterbody Type as A Basis For Different Standards .................................................................. 215 

Essay 20: New Units ...................................................................................................................218 

Introduction ........................................................................................................................................ 218 

Overall Response ................................................................................................................................ 218 

Definition of New Unit ....................................................................................................................... 220 

BTA Requirements for New Units ..................................................................................................... 223 

Projected Baseline Compliance .......................................................................................................... 227 

v 
Implementation ................................................................................................................................... 227 

Notice and Comment .......................................................................................................................... 229 

Essay 21: Development of Compliance Costs ..........................................................................231 

Introduction ........................................................................................................................................ 231 

Summary of Changes to Cost Estimation Methodology .................................................................... 231 

IM Technology Cost Development .................................................................................................... 232 

Baseline Compliance ................................................................................................................... 232 

Costing Technology Selection ..................................................................................................... 234 

Technology Costs – Overarching Comments .............................................................................. 237 

Comments Concerning Capital Costs for Specific Facilities ....................................................... 240 

Service Life .................................................................................................................................. 244 

Entrainment Costs Development for Existing Units/Intakes .............................................................. 245 

Closed-Cycle Cooling for Existing Units at Generators .............................................................. 246 

Closed-Cycle Cooling for Existing Intakes at Manufacturers ..................................................... 251 

New Unit Costs .................................................................................................................................. 252 

Other Cost Comments ........................................................................................................................ 253 

Essay 22: Implementation .........................................................................................................254 

Introduction ........................................................................................................................................ 254 

General Implementation ..................................................................................................................... 254 

Short-Term Exceedances .................................................................................................................... 255 

Application to Each Intake ................................................................................................................. 256 

Compliance Deadlines and Implementation Schedules ...................................................................... 256 

NPDES Permit Application Cycle ............................................................................................... 256 

Harmonizing IM and EM Requirements and the Compliance Timeline ..................................... 258 

Nuclear Facilities ......................................................................................................................... 260 

Consideration of Remaining Useful Plant Life ............................................................................ 260 

Facility Retirement....................................................................................................................... 260 

Considering Use of New Technologies ....................................................................................... 261 

Permit Development and Review Resource Constraints ............................................................. 261 

Clarifying “As Soon As Possible” and “Additional Time” ......................................................... 261 

Requiring Interim Measures ........................................................................................................ 262 

Cooling Water Intake Thresholds ....................................................................................................... 262 

NPDES Permit Application Requirements ......................................................................................... 263 

Application Requirements Submittal Dates ....................................................................................... 263 

vi
BTA Standard for Impingement Mortality ......................................................................................... 264 

Barrier Nets .................................................................................................................................. 265 

Entrapment ................................................................................................................................... 265 

Entrainment Mortality Reduction Requirements ................................................................................ 265 

100 Percent Mortality of Entrainment Organisms ....................................................................... 266 

Land Availability ......................................................................................................................... 266 

Description of Entrainment Survival Study ................................................................................. 266 

Application Requirements .................................................................................................................. 267 

Exemptions for Peaking Units ..................................................................................................... 267 

Peer Review ................................................................................................................................. 268 

Benefits Valuation Study ............................................................................................................. 268 

Default Values for Permit Applications ....................................................................................... 269 

Use of Existing Studies or Data ................................................................................................... 269 

Chosen Method of Compliance with Impingement Mortality Standard ...................................... 270 

Entrainment Characterization Study ............................................................................................ 270 

Monitoring Requirements ................................................................................................................... 271 

Clarifying “Direct Measure” ........................................................................................................ 273 

Annual Average ........................................................................................................................... 273 

Species of Concern and Fragile Species ...................................................................................... 273 

Effects of Debris .......................................................................................................................... 276 

IM Monitoring Methods .............................................................................................................. 276 

IM Monitoring at Each Intake ...................................................................................................... 277 

Remote and Visual Inspection ..................................................................................................... 278 

Monitoring Feasibility ................................................................................................................. 278 

Taxonomic Identification ............................................................................................................. 279 

Converts ....................................................................................................................................... 280 

Moribund Organisms ................................................................................................................... 280 

Biofouling .................................................................................................................................... 280 

Zero Catch .................................................................................................................................... 281 

New Units .................................................................................................................................... 281 

Counting Impinged Organisms with the “Hypothetical Net” ...................................................... 281 

Methods for Evaluating Latent Mortality Effects Resulting from Impingement ............................... 282 

Reporting Requirements and Record Keeping ................................................................................... 283 

Compliance with Other Laws ............................................................................................................. 284 

State 316(b) Programs.................................................................................................................. 285 

vii
Director’s Role ................................................................................................................................... 286 

Setting More Stringent Standards ................................................................................................ 286 

Permit Proceedings Begun Prior to the Effective Date of the Final Rule .................................... 286 

Establishing a Policy to Disallow EPA Comments ..................................................................... 287 

Requiring Additional Information ............................................................................................... 287 

Communications and Outreach .................................................................................................... 287 

Dry/Hybrid Cooling Towers............................................................................................................... 288 

Social Cost-Benefit Analysis in Establishing Entrainment Standards ............................................... 288 

Essay 23: EPA’s Information Collection Request (ICR) and Administrative Costs of 

the Rule ...................................................................................................................................290 

Essay 24: Technical Development Document ..........................................................................292 

Introduction ........................................................................................................................................ 292 

Basis for Developing Costs ................................................................................................................ 292 

Technology Performance.................................................................................................................... 294 

Site-Specific Data for Capacity Utilization Rate ................................................................................ 297 

Analysis of Uncertainty ...................................................................................................................... 298 

Essay 29: Cumulative Impact of Multiple EPA Regulations on the Electric Power 

Sector ......................................................................................................................................299 

Overview of Comments ...................................................................................................................... 299 

Impact of the 316(b) Final Rule in the Context of Multiple Environmental Regulations 

Affecting the Electric Power Industry ................................................................................................ 300 

Impact of 316(b) Final Rule on Electricity Rates, Total Economy, and Employment ....................... 301 

Need for Consultation and Coordination ............................................................................................ 301 

Impact on Coal Usage and the Coal Industry ..................................................................................... 302 

Impact on Coal-Refuse Based Generation ......................................................................................... 302 

Adverse Impact on Decisions to Build New Units ............................................................................. 302 

Adverse Impact Due to Compressed and Overlapping Compliance Periods from Multiple 

Regulations ......................................................................................................................................... 302 

Financial Losses from Capacity Retirements .................................................................................. 303 

Potential Impact on Grid Stability and Transmission System Reliability .................................... 303 

Essay 31: Cost and Economic Impact Analysis: Methods and Approaches ........................305 

Overview of Comments ...................................................................................................................... 305 

Annualization of Costs and Benefits .................................................................................................. 306 

Claim of Inconsistencies in Annualization Periods ..................................................................... 306 

viii
The 50-Year Annualization Period Used for the Proposed Rule Understates Costs; 

Recommendation to Use 10-Year Annualization Period Based on Congressional Budget 

Office (CBO) ............................................................................................................................... 308 

Use of Annualization Periods for the Proposed 316(b) Existing Facilities Rule Analysis 

that Differ from the Periods Used in the Previous 316(b) Rulemaking Analyses ....................... 308 

Use of 30-Year Period for Modeling Benefits for the Individual Facility ................................... 309 

Cost and Economic Impact Analysis Assumptions and Analytic Approach ...................................... 309 

Use of Sum of Facility-Level Revenue for Entity-Level Cost-to-Revenue Analysis .................. 309 

Underestimation of Cost Per Unit in Sales to Customers ............................................................ 309 

Underestimation of the Rule’s Costs because of Failure to Account for Closing Facilities ........ 310 

Assertion that Cost-to-Revenue Analysis is Not an Appropriate Measure of Impact ................. 310 

Assertion that the Cost and Economic Impact Analysis Does Not Account for Conditions 

in Specific Industries.................................................................................................................... 311 

Assertion that Cost Pass-Through Assumptions are Overly Conservative .................................. 311 

Essay 35: Installation Downtime for Manufacturing and Non-Electric Power 

Generating Facilities .............................................................................................................312 

Introduction ........................................................................................................................................ 312 

History of the Development of Downtime Estimates for IM Controls for Manufacturers ................. 312 

Length of Downtime for Installation of IM Controls ......................................................................... 312 

Costs of Downtime for Installation of IM Controls ........................................................................... 315 

Length of Downtime and Associated Costs for Installing Entrainment Controls .............................. 317 

Industry or Facility-Specific Downtime ............................................................................................. 319 

Other Downtime Comments ............................................................................................................... 320 

Essay 36: Employment Effects Analysis ..................................................................................322 

Overview of Comments ...................................................................................................................... 322 

General Response .............................................................................................................................. 322 

Failure to Perform a Quantitative Employment Effects Analysis ...................................................... 323 

Analysis of Electricity Rate Effects on Employment ......................................................................... 324 

Use of Other Methodologies and Data for Performing Employment Effects Analysis...................... 325 

Recommendation to Use the Labor Intensity Coefficient Developed from NERA Study 

for the Employment Analysis ...................................................................................................... 325 

Recommendation That EPA Estimate Job Effects in the Electric Power Sector Based on 

Potential Loss in Electric Generating Capacity from the Market Model Analysis ...................... 325 

Recommendation to Use Results from Other Studies in the Employment Effects Analysis ....... 326 

Failure to Account for the Employment Loss in Baseline Closure of Manufacturers Facilities ........ 326 

ix
Failure to Recognize that Proposal Option 3 Would Result in the Least Adverse Impact on 

Employment ....................................................................................................................................... 327 

Arguments Supporting the Existing Facilities Rule Based on Potential Employment 

Requirements ...................................................................................................................................... 327 

Essay 37: Adverse Impacts on National, State, and Local Economies ..................................328 

Essay 38: Impact on Rural Electric Cooperatives ..................................................................331 

Essay 39: Reliability and Electricity Rate Impacts .................................................................333 

Overview of Comments ...................................................................................................................... 333 

General Concerns Regarding Reliability and Electricity Rate Impact ............................................... 334 

Potential Capacity Closures Due to the Final Rule ............................................................................ 335 

Argument that Capacity Closures and Related Reliability and Rate Effects under an AllCooling Tower Regulation Would be Acceptable .............................................................................. 336 

Argument that Adverse Capacity Effects are Overstated because of Overly Conservative 

Assumptions in the IPM Analysis ...................................................................................................... 336 

Argument that Overly Conservative Consumptions Regarding Cost Pass-Through Lead to 

Overstatement of Impacts on Consumers and Overstatement of Impacts on Regulated 

Facilities ............................................................................................................................................. 337 

Overall Argument Favoring an All Cooling Tower Regulation ......................................................... 337 

Potential Impact of Rule on Electricity Consumers ........................................................................... 338 

Argument that Limited Timeframe for Regulatory Compliance May Lead to Difficulties in 

Facilities Achieving Compliance with the Rule, with Associated Reliability and Rate Impacts ....... 338 

Undesirable Transfers of Income from Consumers to Electricity Generators ................................... 339 

Assertion that EPA Assess the Potential Impact of Electricity Rate Increases on Low Income 

Consumers .......................................................................................................................................... 339 

EPA Should Consider Alternative Compliance Standards for Load-Following and Peaking 

Generating Units ................................................................................................................................. 339 

Essay 45: Market Model Analysis Conducted Using IPM .....................................................340 

Some Results Concerning Electricity Rates Appear Contradictory and/or Counterintuitive ............. 341 

Use of an Older IPM Platform and Potential Overstatement of Rule Impacts ................................... 341 

Essay 47: Economic Impacts on Manufacturers .....................................................................343 

Essay 48: Rule Should Establish Performance Metrics to Track and Validate Public 

Policy Value of Rule's Requirements...................................................................................346 

Essay 50: Alternative Compliance Responses .........................................................................347 

x 
Essay 53: Electricity Rate and Reliability Impact to be Considered During SiteSpecific Evaluation ................................................................................................................349 

Essay 55: Facility-Level Compliance Costs, Social Costs, and Costs to be Submitted 

as Part of the Comprehensive Technical Feasibility and Cost Evaluation Study ...........350 

Essay 58: EPA’s Consultation and Stakeholder Outreach ....................................................353 

Essay 59: Executive Orders 12866: Regulatory Planning and Review and 13563: 

Improving Regulation and Regulatory Review ..................................................................355 

Comments on the Relationship between Social Cost and Benefits and EPA’s Selection of and 

Support for the Proposed Rule ........................................................................................................... 356 

Failure to Provide Time Profile of Social Costs and Benefits ............................................................ 356 

Failure to Explain How Benefits Justify Costs ................................................................................... 356 

Failure to Quantify the Effect on Employment .................................................................................. 357 

EPA Should Consider the Current State of the U.S. Economy .......................................................... 358 

Failure to Consider the Costs and Effects of Other Rules .................................................................. 358 

Need to Assess Reliability Effects ..................................................................................................... 358 

Need for Performance Metrics Pursuant to EO 13563 ....................................................................... 358 

Rule Does Not Set Performance Objectives ....................................................................................... 358 

Essay 60: Other Federal Statutes .............................................................................................359 

Essay 64: Inter-Agency Review ................................................................................................361 

Essay 68: New Capacity.............................................................................................................362 

Essay 70: General Comments on Nonuse Benefits..................................................................363 

Essay 71: Benefit Categories .....................................................................................................368 

Excluded Benefit Categories .............................................................................................................. 368 

Economic and Cultural Benefits ......................................................................................................... 369 

Site Benefits ....................................................................................................................................... 371 

Distributional Effects ......................................................................................................................... 371 

Essay 72: Benefits to Threatened and Endangered Species and Endangered Species 

Act Consultation ....................................................................................................................372 

Monetized Benefits of Threatened and Endangered Species ............................................................. 372 

Assumptions Regarding Baseline Losses ........................................................................................... 372 

xi 
Essay 73: Commercial and Recreational Fishing Benefits .....................................................374 

Fishery Yield ...................................................................................................................................... 374 

Commercial Fishing Market Complexity ........................................................................................... 374 

Great Lakes Study .............................................................................................................................. 375 

Recreational Fishing Benefits Analysis Method ................................................................................ 375 

Declining Marginal Utility ................................................................................................................. 378 

Environmental Justice ........................................................................................................................ 379 

Essay 74: Nonuse Benefits Analysis Methods ..........................................................................380 

Limiting the Transfer to Two Regions ............................................................................................... 380 

Criticism of the Rhode Island Stated Preference Study ..................................................................... 381 

EPA’s Application of the Rhode Island Study ................................................................................... 384 

Essay 75: Nonuse Benefits on Reducing I&E Mortality: Habitat-based Approach ............386 

Role of Habitat-Based Approach Results ........................................................................................... 386 

Assumptions in the Habitat-Based Approach ..................................................................................... 386 

The Habitat-Based Method’s Unrealistic Results .............................................................................. 387 

Response to Comments ...................................................................................................................... 387 

Essay 76: Break Even Analysis .................................................................................................388 

Introduction ........................................................................................................................................ 388 

Riverkeeper Comments ...................................................................................................................... 388 

UWAG Comments ............................................................................................................................. 389 

Essay 77: 316(b) Stated Preference Survey .............................................................................391 

Nonuse Values .................................................................................................................................... 392 

Use for Cost-Benefit Analysis ............................................................................................................ 392 

Essay 78: National Benefits .......................................................................................................395 

Benefits are Underestimated............................................................................................................... 395 

Benefits are Overestimated................................................................................................................. 397 

Essay 81: Loss Metrics...............................................................................................................400 

Essay 82: Assessment and Extrapolation of Impingement Mortality and 

Entrainment ...........................................................................................................................402 

Data Quality and Age ......................................................................................................................... 402 

Problems with Age Equivalency Models ........................................................................................... 403 

xii 
Biomass Transfer Among Trophic Levels.......................................................................................... 404 

Extrapolation from Facilities to Regions ............................................................................................ 405 

Limitations and Uncertainty ............................................................................................................... 405 

Essay 83: Entrainment Mortality .............................................................................................408 

Assumption of 100 Percent Entrainment Mortality ............................................................................ 408 

Relevance to the Final Rule and Determination of BTA .................................................................... 409 

Essay 84: Impacts on Threatened and Endangered Species ..................................................410 

Inability to Account for All Impacts .................................................................................................. 410 

Impacts of Regulated Facilities on T&E Species ............................................................................... 410 

Potential for IM&E of T&E Species .................................................................................................. 411

xiii
Introduction 

Introduction

On April 20, 2011 EPA published a proposed rule to establish nationally applicable requirements 

under section 316(b) of the Clean Water Act (CWA) for existing power generating facilities and 

existing manufacturing and industrial facilities. EPA also proposed revisions to the Phase I new 

facility rule in response to the Riverkeeper I decision. On June 11 and 12, 2012, EPA published a 

pair of Notices of Data Availability (NODAs); the first regarding information on impingement 

mortality controls and the second regarding information on EPA’s stated preference survey. 

Between the three notices, EPA received more than 63,000 comments under Docket ID EPAHQ-OW-2008-0667. 

EPA parsed comment letters into discrete sections according to the subject matter addressed in 

the given section of the letter (i.e., a comment letter may be broken into as many parts as there 

are issues raised). EPA then developed responses to each of these comments in the form of broad 

essays that address all of the comments within a subject matter area.

The final responses to comment document consists of the following: 

• Introductory Chapter: Familiarizes commenters with the process EPA used to divide 

comments into similar issues for response and helps commenters learn how to find 

responses to their comments. 

• Response to Comment Essays: Provides each of the comment response essays. 

This Introductory Chapter describes the following: 

A. Methodology EPA used to sort and code public comment letters 

B. Locating your comments and EPA’s response in the final document 

C. Duplicates, attachments, mass mail campaigns, and keyword searches 

D. Disclaimer

A. Methodology EPA Used to Sort and Code Public Comment Letters

In responding to public comments, EPA used the following methodology to sort and code 

comment letters into similar topics for response:

1. Assigned each letter an Author ID based on the number generated by the Federal Docket 

Management System (FDMS). 

2. Reviewed each letter in its entirety, including any attachments.

3. Identified the major subjects addressed in each letter and assigned them to specific issue 

categories (also known as “comment coding”). For most letters, this results in multiple 

comments per letter. 

4. Drafted a response in each issue category, using an essay format to address all comments 

within an issue category simultaneously.
Introduction 

B. Locating Your Comments and EPA’s Response in the Final Document

All comments on the proposed rule and NODAs are available at 

http://www.regulations.gov/#!docketDetail;D=EPA-HQ-OW-2008-0667. An excerpt from Table 

1 below illustrates that the table contains a list of the commenters, their affiliation, and their 

Document IDs. A full version of Table 1 is included at the end of the Introductory Chapter.

Table 1. Comments on the Proposed Rule and NODAs. 

FDMS Document ID First Name Last Name Organization

EPA-HQ-OW-2008-0667-1288 G. Gries

EPA-HQ-OW-2008-0667-1296 Mass Comment 

Campaign

Alliance for the Great Lakes

EPA-HQ-OW-2008-0667-1298 Mass Comment 

Campaign

Consumer Energy Alliance

EPA-HQ-OW-2008-0667-1299 P. Warren

EPA-HQ-OW-2008-0667-1300 F. Caplan

EPA-HQ-OW-2008-0667-1304 M. W. Birch

EPA-HQ-OW-2008-0667-1305 T. E. McCloskey

EPA-HQ-OW-2008-0667-1325 Elizabeth Aldridge Utility Water Act Group (UWAG)

The Table of Contents contains a list of the response to comment essays, which are divided into 

various subject areas. The essays address comments received on both the proposed rule and 

NODAs. Readers should simply refer to the Table of Contents to identify the subject area of 

interest and the corresponding essay. 

Note that the numbering of the essays may not be sequential; there are gaps in the numbering. 

This resulted from some essays being combined with one another. 

C. Duplicates, Attachments, Mass Mail Campaigns, and Keyword Searches

Duplicates

In rare cases, a comment letter was received more than once. When EPA determined that a 

comment letter was an exact duplicate of another comment letter, EPA did note code the 

duplicate letter.

Attachments

Some comment letters also contained attachments, such as biological studies or engineering cost 

estimates. EPA reviewed all letters for attachments and then reviewed all the attachments. 

Attachments that contained additional data directly relevant to the proposed rule (or NODAs) 

were coded using the same process as standard comments. If the attachment was not directly 

relevant (e.g., a commenter provided a generic newspaper article on the electric generating 

industry), EPA did note code the attachment. EPA considered all attachments in developing the 

final rule and responding to comments, but only coded those that were directly relevant.
Introduction 

Mass Mail Campaigns 

EPA received comments through approximately 15 mass mail campaigns, totaling over 62,000 

comments. EPA only coded those that were posted to www.regulations.gov as unique comment 

letters. EPA’s Water Docket determined whether letters contained the same (or very similar) 

content as others and posted only those that are unique. For example, if two (or more) 

commenters submitted identical comments, the first letter received will appear under the name 

“Mass Comment Campaign” and any subsequent identical (or nearly identical) comments will be 

catalogued within the same record. Similarly, EPA’s response to the “parent” letter applies to all 

of the form letters within that record. Form letters that provided additional substantive comments 

were addressed by responding to the unique material in the relevant response essay. This is 

consistent with EPA’s goals in responding to public comments, as all of the letters received 

under “Mass Comment Campaign” are identical, thereby allowing EPA to respond to the group 

of letters collectively.

Keyword Searches

This document is in Adobe PDF format. Readers may perform word searches using the Acrobat 

Reader: use the Search button or SHIFT-CTRL-F.

D. Disclaimer

As a result of late changes made to the preamble and final rule prior to the Administrator’s 

signature, and due to the volume of comments received, some responses in this document may 

not reflect the language in the preamble and final rule in every respect. Where this is the case, the 

language in the final preamble and rule controls and should be used for purposes of 

understanding the scope, requirements, and basis of the final rule. 
Introduction 

Table 1. Comments on the Proposed Rule and NODAs

FDMS Document ID First Name Middle 

Name Last Name Organization

EPA-HQ-OW-2008-0667-1288 G. Gries

EPA-HQ-OW-2008-0667-1296 Mass Comment 

Campaign

Alliance for the Great Lakes

EPA-HQ-OW-2008-0667-1298 Mass Comment 

Campaign

Consumer Energy Alliance

EPA-HQ-OW-2008-0667-1299 P. Warren

EPA-HQ-OW-2008-0667-1300 F. Caplan

EPA-HQ-OW-2008-0667-1301 V. Heying

EPA-HQ-OW-2008-0667-1302 K. Treacy

EPA-HQ-OW-2008-0667-1303 D. Bryson

EPA-HQ-OW-2008-0667-1304 M. and W. Birch

EPA-HQ-OW-2008-0667-1305 T. and E. McCloskey

EPA-HQ-OW-2008-0667-1306 R. Kane

EPA-HQ-OW-2008-0667-1307 A. Klein

EPA-HQ-OW-2008-0667-1308 G. French

EPA-HQ-OW-2008-0667-1309 T. Bauer

EPA-HQ-OW-2008-0667-1310 M. Wexler

EPA-HQ-OW-2008-0667-1311 M. Janowiak

EPA-HQ-OW-2008-0667-1312 J. Bussen

EPA-HQ-OW-2008-0667-1313 K. Megregian

EPA-HQ-OW-2008-0667-1314 G. Opem

EPA-HQ-OW-2008-0667-1315 S. Hughes

EPA-HQ-OW-2008-0667-1316 J. Gorham

EPA-HQ-OW-2008-0667-1317 A. Jenks

EPA-HQ-OW-2008-0667-1318 Anonymous

EPA-HQ-OW-2008-0667-1319 D. Shwatal

EPA-HQ-OW-2008-0667-1320 M. Brower

EPA-HQ-OW-2008-0667-1321 F. Belogorsky

EPA-HQ-OW-2008-0667-1322 D. Shankland

EPA-HQ-OW-2008-0667-1323 G. Crouse

EPA-HQ-OW-2008-0667-1324 E. N. Van Abel

EPA-HQ-OW-2008-0667-1325 Elizabeth Aldridge Utility Water Act Group (UWAG)

EPA-HQ-OW-2008-0667-1326 E. May

EPA-HQ-OW-2008-0667-1327 Anonymous

EPA-HQ-OW-2008-0667-1328 R. Steiger

EPA-HQ-OW-2008-0667-1329 D. Shumaker
Introduction 

FDMS Document ID First Name Middle 

Name Last Name Organization

EPA-HQ-OW-2008-0667-1330 W. Brickenstein

EPA-HQ-OW-2008-0667-1331 W. Coles

EPA-HQ-OW-2008-0667-1332 A. Baratta

EPA-HQ-OW-2008-0667-1333 H. Neal

EPA-HQ-OW-2008-0667-1334 S. Schueler

EPA-HQ-OW-2008-0667-1335 L. Parker

EPA-HQ-OW-2008-0667-1345 D. Rousseau

EPA-HQ-OW-2008-0667-1346 S. Brower

EPA-HQ-OW-2008-0667-1347 M. Trost

EPA-HQ-OW-2008-0667-1348 A. Kardoff

EPA-HQ-OW-2008-0667-1349 C. Miller

EPA-HQ-OW-2008-0667-1350 J. Yount

EPA-HQ-OW-2008-0667-1351 L. Bond

EPA-HQ-OW-2008-0667-1352 E. McAndrew-Benavides

EPA-HQ-OW-2008-0667-1353 N. Lens

EPA-HQ-OW-2008-0667-1354 M. Greer

EPA-HQ-OW-2008-0667-1355 B. Cummings

EPA-HQ-OW-2008-0667-1356 M. Wisenburg

EPA-HQ-OW-2008-0667-1357 M. Paul

EPA-HQ-OW-2008-0667-1362 R. Termini

EPA-HQ-OW-2008-0667-1363 M. Dowd

EPA-HQ-OW-2008-0667-1372 C. Pixler

EPA-HQ-OW-2008-0667-1373 A. Ohlinger

EPA-HQ-OW-2008-0667-1374 R. Blankenship

EPA-HQ-OW-2008-0667-1375 R. Daniels

EPA-HQ-OW-2008-0667-1468 Dr. D. Hartel

EPA-HQ-OW-2008-0667-1469 J. Biss

EPA-HQ-OW-2008-0667-1470 C. Albee

EPA-HQ-OW-2008-0667-1471 Dr. G. Crouse

EPA-HQ-OW-2008-0667-1472 S. Hathaway

EPA-HQ-OW-2008-0667-1473 H. Chichester

EPA-HQ-OW-2008-0667-1474 D. Rosenberg

EPA-HQ-OW-2008-0667-1475 J. Commerford

EPA-HQ-OW-2008-0667-1476 P. Tullis

EPA-HQ-OW-2008-0667-1477 N. Stevens

EPA-HQ-OW-2008-0667-1478 E. Clark

EPA-HQ-OW-2008-0667-1479 I. Stover

EPA-HQ-OW-2008-0667-1480 Dr. L. Young

EPA-HQ-OW-2008-0667-1481 V. Whicker
Introduction 

FDMS Document ID First Name Middle 

Name Last Name Organization

EPA-HQ-OW-2008-0667-1482 T. E. Robinson

EPA-HQ-OW-2008-0667-1483 S. Anderson

EPA-HQ-OW-2008-0667-1484 B. Anderson

EPA-HQ-OW-2008-0667-1485 D. Gordillo

EPA-HQ-OW-2008-0667-1486 Dr. K. L. and J. Modesitt

EPA-HQ-OW-2008-0667-1487 P. Hanson

EPA-HQ-OW-2008-0667-1488 A. Carissimi

EPA-HQ-OW-2008-0667-1489 T. Piazzon

EPA-HQ-OW-2008-0667-1490 M. Roam

EPA-HQ-OW-2008-0667-1491 L. Grimes

EPA-HQ-OW-2008-0667-1492 D. Ellis

EPA-HQ-OW-2008-0667-1493 D. Shanklin

EPA-HQ-OW-2008-0667-1494 L. Kelly

EPA-HQ-OW-2008-0667-1495 K. Norton

EPA-HQ-OW-2008-0667-1496 C. Cox

EPA-HQ-OW-2008-0667-1497 S. Alex

EPA-HQ-OW-2008-0667-1498 S. and J. Biller

EPA-HQ-OW-2008-0667-1499 G. Meindl

EPA-HQ-OW-2008-0667-1500 M. Mehlman

EPA-HQ-OW-2008-0667-1501 E. Purcell

EPA-HQ-OW-2008-0667-1502 V. Pilkington

EPA-HQ-OW-2008-0667-1503 A. Kelm

EPA-HQ-OW-2008-0667-1504 S. Brodhead

EPA-HQ-OW-2008-0667-1505 E. Perchonock

EPA-HQ-OW-2008-0667-1506 J. Sanborn

EPA-HQ-OW-2008-0667-1507 G. Garrison

EPA-HQ-OW-2008-0667-1508 I. Botvin

EPA-HQ-OW-2008-0667-1509 S. O-Ishi

EPA-HQ-OW-2008-0667-1510 M. Link

EPA-HQ-OW-2008-0667-1511 D. Flores

EPA-HQ-OW-2008-0667-1512 M. Well

EPA-HQ-OW-2008-0667-1513 Rayburn L. Butts NextEra Energy Inc.

EPA-HQ-OW-2008-0667-1514 C. Burke

EPA-HQ-OW-2008-0667-1515 D. Mahle

EPA-HQ-OW-2008-0667-1516 A. Thornton

EPA-HQ-OW-2008-0667-1517 J. S. Dandoval

EPA-HQ-OW-2008-0667-1518 M. Stemp

EPA-HQ-OW-2008-0667-1519 D. Parker

EPA-HQ-OW-2008-0667-1520 L. Champagne
Introduction 

FDMS Document ID First Name Middle 

Name Last Name Organization

EPA-HQ-OW-2008-0667-1521 A. Osmond

EPA-HQ-OW-2008-0667-1522 R. McIntire

EPA-HQ-OW-2008-0667-1523 M. Linvill

EPA-HQ-OW-2008-0667-1524 S. Mehrotra

EPA-HQ-OW-2008-0667-1525 P. Thomas

EPA-HQ-OW-2008-0667-1526 P. Sladek

EPA-HQ-OW-2008-0667-1527 M. Young

EPA-HQ-OW-2008-0667-1528 A. Cortese

EPA-HQ-OW-2008-0667-1529 Maria Valdez The Dow Chemical Company

EPA-HQ-OW-2008-0667-1530 Mass Comment 

Campaign

Natural Resources Defense Council (NRDC)

EPA-HQ-OW-2008-0667-1531 D. Johnson

EPA-HQ-OW-2008-0667-1532 M. Bartleman

EPA-HQ-OW-2008-0667-1533 A. Desai

EPA-HQ-OW-2008-0667-1534 J. Weller

EPA-HQ-OW-2008-0667-1535 D. Smith

EPA-HQ-OW-2008-0667-1536 J. Steitz

EPA-HQ-OW-2008-0667-1537 J. Scott

EPA-HQ-OW-2008-0667-1538 M. Hills

EPA-HQ-OW-2008-0667-1539 P. La Point

EPA-HQ-OW-2008-0667-1540 P. Johnston

EPA-HQ-OW-2008-0667-1541 S. Futrell

EPA-HQ-OW-2008-0667-1542 B. Flowers

EPA-HQ-OW-2008-0667-1546 Dana Wright Tennessee Clean Water Network (TCWN)

EPA-HQ-OW-2008-0667-1547 Al Carlson and Tom Holbrook National Conference of State Legislatures (NCSL)

EPA-HQ-OW-2008-0667-1548 J. Capozzelli

EPA-HQ-OW-2008-0667-1549 Al Carlson and Tom Holbrook National Conference of State Legislatures (NCSL)

EPA-HQ-OW-2008-0667-1550 Mass Comment 

Campaign

Environmental Law and Policy Center

EPA-HQ-OW-2008-0667-1551 Mass Comment 

Campaign

Sierra Club

EPA-HQ-OW-2008-0667-1552 J. Sorrells

EPA-HQ-OW-2008-0667-1553 M. Huff

EPA-HQ-OW-2008-0667-1554 L. Barrett

EPA-HQ-OW-2008-0667-1555 C. Piper

EPA-HQ-OW-2008-0667-1556 D. Robertson

EPA-HQ-OW-2008-0667-1557 E. B. Robbins

EPA-HQ-OW-2008-0667-1558 R. Penney

EPA-HQ-OW-2008-0667-1559 R. Baker
Introduction 

FDMS Document ID First Name Middle 

Name Last Name Organization

EPA-HQ-OW-2008-0667-1560 K. Rowlett

EPA-HQ-OW-2008-0667-1561 T. Kruskie

EPA-HQ-OW-2008-0667-1562 Dr. J. Livingston

EPA-HQ-OW-2008-0667-1563 Ed and S. Harney

EPA-HQ-OW-2008-0667-1564 C. Carter

EPA-HQ-OW-2008-0667-1565 C. Mies

EPA-HQ-OW-2008-0667-1566 J. Robinson

EPA-HQ-OW-2008-0667-1567 A. Murre

EPA-HQ-OW-2008-0667-1568 J. Rooks

EPA-HQ-OW-2008-0667-1569 N. Husnani

EPA-HQ-OW-2008-0667-1570 B. Wagman

EPA-HQ-OW-2008-0667-1571 B. Katakis

EPA-HQ-OW-2008-0667-1572 E. Lofftus

EPA-HQ-OW-2008-0667-1573 K. Davis

EPA-HQ-OW-2008-0667-1574 C. Jacob

EPA-HQ-OW-2008-0667-1575 L. Calleja

EPA-HQ-OW-2008-0667-1576 M. (no last name 

provided)

EPA-HQ-OW-2008-0667-1577 D. R. Nelson

EPA-HQ-OW-2008-0667-1578 R. Kerrill

EPA-HQ-OW-2008-0667-1579 B. Eaton

EPA-HQ-OW-2008-0667-1580 G. Neumann

EPA-HQ-OW-2008-0667-1581 M. Menzel

EPA-HQ-OW-2008-0667-1582 C. May

EPA-HQ-OW-2008-0667-1583 K. Massanari

EPA-HQ-OW-2008-0667-1584 R. Heiser

EPA-HQ-OW-2008-0667-1585 D. Duda

EPA-HQ-OW-2008-0667-1586 L. Stevens

EPA-HQ-OW-2008-0667-1587 N. Dean

EPA-HQ-OW-2008-0667-1588 N. Bilheimer

EPA-HQ-OW-2008-0667-1589 J. Sorrells

EPA-HQ-OW-2008-0667-1590 S. Harris

EPA-HQ-OW-2008-0667-1591 B. Prewitt

EPA-HQ-OW-2008-0667-1592 D. Cohn

EPA-HQ-OW-2008-0667-1593 Matthew Bell Regional Chamber of Northeast Indiana

EPA-HQ-OW-2008-0667-1594 Anonymous

EPA-HQ-OW-2008-0667-1595 Scott Manley Wisconsin Manufacturers & Commerce (WMC)

EPA-HQ-OW-2008-0667-1596 Roger E. Nott Georgia Canoeing Association, Inc.

EPA-HQ-OW-2008-0667-1597 N. Wilson
Introduction 

FDMS Document ID First Name Middle 

Name Last Name Organization

EPA-HQ-OW-2008-0667-1598 Donald R. Carlson Kansas Department of Health and Environment (KDHE)

EPA-HQ-OW-2008-0667-1599 Alex Levinson Pacific Environment

EPA-HQ-OW-2008-0667-1600 M. Aggar

EPA-HQ-OW-2008-0667-1601 D. K. Oberlin Jr.

EPA-HQ-OW-2008-0667-1602 K. Fisher

EPA-HQ-OW-2008-0667-1603 State Rep. Paul Stam, et al. North Carolina State House of Representatives

EPA-HQ-OW-2008-0667-1604 State Sen. Amy Koch Minnesota State Senate, District 19

EPA-HQ-OW-2008-0667-1605 W. Hardman

EPA-HQ-OW-2008-0667-1606 M. Reback

EPA-HQ-OW-2008-0667-1607 K. Jackson

EPA-HQ-OW-2008-0667-1608 J. Conway

EPA-HQ-OW-2008-0667-1609 L. Langston

EPA-HQ-OW-2008-0667-1610 L. Perenne

EPA-HQ-OW-2008-0667-1612 D. Hibbs

EPA-HQ-OW-2008-0667-1613 J. Morris

EPA-HQ-OW-2008-0667-1614 M. Schindler-Ehrens

EPA-HQ-OW-2008-0667-1615 S. Pardo

EPA-HQ-OW-2008-0667-1616 J. Olson

EPA-HQ-OW-2008-0667-1617 B. Dixon-Smith

EPA-HQ-OW-2008-0667-1618 A. Howe

EPA-HQ-OW-2008-0667-1619 E. Daniel

EPA-HQ-OW-2008-0667-1620 F. Mead

EPA-HQ-OW-2008-0667-1621 K. Walker

EPA-HQ-OW-2008-0667-1622 M. Hower

EPA-HQ-OW-2008-0667-1623 D. Filipelli

EPA-HQ-OW-2008-0667-1624 N. Black

EPA-HQ-OW-2008-0667-1625 S. Chait

EPA-HQ-OW-2008-0667-1626 T. Sheffield

EPA-HQ-OW-2008-0667-1627 P. Lipari

EPA-HQ-OW-2008-0667-1628 J. Owen

EPA-HQ-OW-2008-0667-1630 Anonymous

EPA-HQ-OW-2008-0667-1631 Jeff Udd Minnesota Pollution Control Agency (MPCA)

EPA-HQ-OW-2008-0667-1632 Susan R. Nanney Passaic River Coalition

EPA-HQ-OW-2008-0667-1633 M. Allard

EPA-HQ-OW-2008-0667-1634 D. Goodman

EPA-HQ-OW-2008-0667-1635 C. Kutcher

EPA-HQ-OW-2008-0667-1636 K. Robinett

EPA-HQ-OW-2008-0667-1637 State Rep. John D. Ragan Tennessee State House of Representatives
Introduction 

FDMS Document ID First Name Middle 

Name Last Name Organization

EPA-HQ-OW-2008-0667-1638 Thomas W. Easterly Indiana Department of Environmental Management 

(IDEM)

EPA-HQ-OW-2008-0667-1639 R. Benson

EPA-HQ-OW-2008-0667-1640 Blake Jeffery Indiana Cast Metals Association (INCMA)

EPA-HQ-OW-2008-0667-1641 Blake Jeffery Indiana Cast Metals Association (INCMA)

EPA-HQ-OW-2008-0667-1642 Fred Abousleman National Association of Regional Councils (NARC)

EPA-HQ-OW-2008-0667-1643 Robert A. Rio Associated Industries of Massachusetts (AIM)

EPA-HQ-OW-2008-0667-1644 Barry E. Lamb Friends of the Bay

EPA-HQ-OW-2008-0667-1645 Joaquin C. Flores Guam Power Authority (GPA)

EPA-HQ-OW-2008-0667-1646 James D. Atterholt, et al. Indiana Utility Regulatory Commission (IURC)

EPA-HQ-OW-2008-0667-1647 State Sen. Philip E. Berger, et al. North Carolina State Senate

EPA-HQ-OW-2008-0667-1648 W. Brickenstein

EPA-HQ-OW-2008-0667-1649 S. Black

EPA-HQ-OW-2008-0667-1650 S. Larson

EPA-HQ-OW-2008-0667-1651 J. R. Bracken

EPA-HQ-OW-2008-0667-1652 K. Venditti

EPA-HQ-OW-2008-0667-1653 S. Wolf

EPA-HQ-OW-2008-0667-1654 W. Aldrich

EPA-HQ-OW-2008-0667-1655 L. Anderson

EPA-HQ-OW-2008-0667-1656 M. Yeager

EPA-HQ-OW-2008-0667-1657 H. Manzella

EPA-HQ-OW-2008-0667-1658 E. L. Springer, Jr.

EPA-HQ-OW-2008-0667-1659 K. Rowlett

EPA-HQ-OW-2008-0667-1660 T. Row

EPA-HQ-OW-2008-0667-1661 Dr. W. H. Hannum

EPA-HQ-OW-2008-0667-1662 R. Termini

EPA-HQ-OW-2008-0667-1663 M. Angwin

EPA-HQ-OW-2008-0667-1664 M. Hulet

EPA-HQ-OW-2008-0667-1665 P. Sicard

EPA-HQ-OW-2008-0667-1666 R. Hodge

EPA-HQ-OW-2008-0667-1667 C. Sekaer

EPA-HQ-OW-2008-0667-1668 B. Flowers

EPA-HQ-OW-2008-0667-1669 F. Brice

EPA-HQ-OW-2008-0667-1670 J. Vickerman

EPA-HQ-OW-2008-0667-1671 M. Paul

EPA-HQ-OW-2008-0667-1672 State Sen. Paul G. Campbell, Jr. South Carolina State Senate

EPA-HQ-OW-2008-0667-1673 N. J. Scanlon

EPA-HQ-OW-2008-0667-1674 J. Capozzelli

EPA-HQ-OW-2008-0667-1675 H. Thompsom
Introduction 

FDMS Document ID First Name Middle 

Name Last Name Organization

EPA-HQ-OW-2008-0667-1676 J. Sorrells

EPA-HQ-OW-2008-0667-1677 F. Stowell

EPA-HQ-OW-2008-0667-1678 S. Slawek

EPA-HQ-OW-2008-0667-1679 J. Dunkelberg

EPA-HQ-OW-2008-0667-1680 G. Burton

EPA-HQ-OW-2008-0667-1681 J. Fox

EPA-HQ-OW-2008-0667-1682 L. Bowdery

EPA-HQ-OW-2008-0667-1683 T. Volz-Bongar

EPA-HQ-OW-2008-0667-1684 J. Kellner

EPA-HQ-OW-2008-0667-1685 T. Smith

EPA-HQ-OW-2008-0667-1686 M. Magee

EPA-HQ-OW-2008-0667-1687 S. Prussman

EPA-HQ-OW-2008-0667-1688 M. Morey

EPA-HQ-OW-2008-0667-1689 Rick Wajda Indiana Builders Association (IBA)

EPA-HQ-OW-2008-0667-1690 J. Conlon

EPA-HQ-OW-2008-0667-1691 Jon H. Harner Donald C. Cook Nuclear Plant (Indiana Michigan Power 

Co.)

EPA-HQ-OW-2008-0667-1692 C. Bergesen

EPA-HQ-OW-2008-0667-1693 Anonymous

EPA-HQ-OW-2008-0667-1694 J. and W. MacDonald

EPA-HQ-OW-2008-0667-1695 G. Spencer

EPA-HQ-OW-2008-0667-1696 D. Halbe

EPA-HQ-OW-2008-0667-1697 H. Hanna

EPA-HQ-OW-2008-0667-1698 C. Sims

EPA-HQ-OW-2008-0667-1699 P. Childs

EPA-HQ-OW-2008-0667-1700 S. Shaw

EPA-HQ-OW-2008-0667-1701 State Sen. Brian Schoenjahn Iowa State Senate, District 12

EPA-HQ-OW-2008-0667-1702 State Rep. Gene Pelowski, Jr. Minnesota State House of Representatives, District 31A

EPA-HQ-OW-2008-0667-1703 Barry Gullet Catawba-Wateree Water Management Group

EPA-HQ-OW-2008-0667-1704 J. Reynolds

EPA-HQ-OW-2008-0667-1705 R. Juras

EPA-HQ-OW-2008-0667-1706 R. Warren

EPA-HQ-OW-2008-0667-1707 L. Young

EPA-HQ-OW-2008-0667-1708 J. Wagner

EPA-HQ-OW-2008-0667-1709 D. Holland

EPA-HQ-OW-2008-0667-1710 P. Lawrence

EPA-HQ-OW-2008-0667-1711 R. Heron

EPA-HQ-OW-2008-0667-1712 P. Sladek

EPA-HQ-OW-2008-0667-1713 P. Bourgeois
Introduction 

FDMS Document ID First Name Middle 

Name Last Name Organization

EPA-HQ-OW-2008-0667-1714 B. Baker

EPA-HQ-OW-2008-0667-1715 E. Elder

EPA-HQ-OW-2008-0667-1716 C. Owen

EPA-HQ-OW-2008-0667-1717 J. Maisel

EPA-HQ-OW-2008-0667-1718 J. Bleyer

EPA-HQ-OW-2008-0667-1719 A. Mondragon

EPA-HQ-OW-2008-0667-1720 F. Taylor

EPA-HQ-OW-2008-0667-1721 R. Airborne

EPA-HQ-OW-2008-0667-1722 B. Flowers

EPA-HQ-OW-2008-0667-1723 N. Poore

EPA-HQ-OW-2008-0667-1724 E. Crow

EPA-HQ-OW-2008-0667-1725 D. Pino

EPA-HQ-OW-2008-0667-1726 E. Craig

EPA-HQ-OW-2008-0667-1727 D. Borton

EPA-HQ-OW-2008-0667-1728 T. Gillespie

EPA-HQ-OW-2008-0667-1729 S. Lannin

EPA-HQ-OW-2008-0667-1730 W. Brown

EPA-HQ-OW-2008-0667-1731 M. Colyar

EPA-HQ-OW-2008-0667-1732 B. Winholtz

EPA-HQ-OW-2008-0667-1733 P. Baum

EPA-HQ-OW-2008-0667-1734 T. Selle

EPA-HQ-OW-2008-0667-1735 J. Valek

EPA-HQ-OW-2008-0667-1736 V. Keramaty

EPA-HQ-OW-2008-0667-1737 V. Keramaty

EPA-HQ-OW-2008-0667-1738 J. Nappe

EPA-HQ-OW-2008-0667-1739 M. Sawyer

EPA-HQ-OW-2008-0667-1740 M. Wood

EPA-HQ-OW-2008-0667-1741 H. Pierson

EPA-HQ-OW-2008-0667-1742 B. O'Brien

EPA-HQ-OW-2008-0667-1743 M. Leonardi

EPA-HQ-OW-2008-0667-1744 R. Tice

EPA-HQ-OW-2008-0667-1745 J. Kieffer

EPA-HQ-OW-2008-0667-1746 R. Chong

EPA-HQ-OW-2008-0667-1747 L. Conklin

EPA-HQ-OW-2008-0667-1748 M. Cronin

EPA-HQ-OW-2008-0667-1749 D. Fulton

EPA-HQ-OW-2008-0667-1750 C. Nelson

EPA-HQ-OW-2008-0667-1751 P. Blochowiak

EPA-HQ-OW-2008-0667-1752 T. and E. Kane
Introduction 

FDMS Document ID First Name Middle 

Name Last Name Organization

EPA-HQ-OW-2008-0667-1753 T. Brainerd

EPA-HQ-OW-2008-0667-1754 K. Tibbits

EPA-HQ-OW-2008-0667-1755 C. Jackson

EPA-HQ-OW-2008-0667-1756 A. Bowen

EPA-HQ-OW-2008-0667-1757 P. Shaw

EPA-HQ-OW-2008-0667-1758 M. M. Switlik

EPA-HQ-OW-2008-0667-1759 R. Owen

EPA-HQ-OW-2008-0667-1760 T. Dessenberger

EPA-HQ-OW-2008-0667-1761 P. Lowe

EPA-HQ-OW-2008-0667-1762 Bernadette McNulty

EPA-HQ-OW-2008-0667-1763 J. Reinert

EPA-HQ-OW-2008-0667-1764 P. Trivelas

EPA-HQ-OW-2008-0667-1765 J. Wisboro

EPA-HQ-OW-2008-0667-1766 L. Winslow

EPA-HQ-OW-2008-0667-1767 Gary S.

EPA-HQ-OW-2008-0667-1768 T. Crockett

EPA-HQ-OW-2008-0667-1769 C. Hubbe

EPA-HQ-OW-2008-0667-1770 N. Tichi

EPA-HQ-OW-2008-0667-1771 M. Iorio

EPA-HQ-OW-2008-0667-1772 J. Knapp

EPA-HQ-OW-2008-0667-1773 M. Cittadino

EPA-HQ-OW-2008-0667-1774 V. Nguyen

EPA-HQ-OW-2008-0667-1775 L. Gieser

EPA-HQ-OW-2008-0667-1776 C. Ehrhardt

EPA-HQ-OW-2008-0667-1777 C. Roth

EPA-HQ-OW-2008-0667-1778 V. Calenda

EPA-HQ-OW-2008-0667-1779 W. Davis

EPA-HQ-OW-2008-0667-1780 F. Jakobcic

EPA-HQ-OW-2008-0667-1781 J. Cooke

EPA-HQ-OW-2008-0667-1782 E. Ungar

EPA-HQ-OW-2008-0667-1783 L. and G. Cook

EPA-HQ-OW-2008-0667-1784 A. Manganelli

EPA-HQ-OW-2008-0667-1785 G. Lee

EPA-HQ-OW-2008-0667-1786 K. Merwin

EPA-HQ-OW-2008-0667-1787 S. Hathaway

EPA-HQ-OW-2008-0667-1788 P. Riggle

EPA-HQ-OW-2008-0667-1789 M. H. Stokes

EPA-HQ-OW-2008-0667-1790 R. Stambaugh

EPA-HQ-OW-2008-0667-1791 J. Cunningham
Introduction 

FDMS Document ID First Name Middle 

Name Last Name Organization

EPA-HQ-OW-2008-0667-1792 E. Callenbach

EPA-HQ-OW-2008-0667-1793 J. Millikin

EPA-HQ-OW-2008-0667-1794 M. Pezzati

EPA-HQ-OW-2008-0667-1795 E. Schlaikjer

EPA-HQ-OW-2008-0667-1796 J. Chase

EPA-HQ-OW-2008-0667-1797 G. Hopkins

EPA-HQ-OW-2008-0667-1798 A. Heugel

EPA-HQ-OW-2008-0667-1799 E. Leviseur

EPA-HQ-OW-2008-0667-1800 L. Zeis

EPA-HQ-OW-2008-0667-1801 N. Reed

EPA-HQ-OW-2008-0667-1802 B. Hall

EPA-HQ-OW-2008-0667-1803 C. Willett

EPA-HQ-OW-2008-0667-1804 L. Carpenter

EPA-HQ-OW-2008-0667-1805 L. Wally

EPA-HQ-OW-2008-0667-1806 K. Young

EPA-HQ-OW-2008-0667-1807 D. Luck

EPA-HQ-OW-2008-0667-1808 K. Crane

EPA-HQ-OW-2008-0667-1809 M. Cleveland-Ryan

EPA-HQ-OW-2008-0667-1810 D. Cleveland-Ryan

EPA-HQ-OW-2008-0667-1811 L. Weinberg

EPA-HQ-OW-2008-0667-1812 T. MacKenzie

EPA-HQ-OW-2008-0667-1813 M. W. Hutson

EPA-HQ-OW-2008-0667-1814 V. Azpuru

EPA-HQ-OW-2008-0667-1815 S. Kuticka

EPA-HQ-OW-2008-0667-1816 Dr. C. Blaisdell

EPA-HQ-OW-2008-0667-1817 S. Calender

EPA-HQ-OW-2008-0667-1818 K. Greenwald

EPA-HQ-OW-2008-0667-1819 L. Kostalik

EPA-HQ-OW-2008-0667-1820 J. Shields

EPA-HQ-OW-2008-0667-1821 B. De Castro

EPA-HQ-OW-2008-0667-1822 K. A. Irwin

EPA-HQ-OW-2008-0667-1823 C. W. Gloger

EPA-HQ-OW-2008-0667-1824 A. Murphy

EPA-HQ-OW-2008-0667-1825 M. Swiger

EPA-HQ-OW-2008-0667-1826 P. Hopkins

EPA-HQ-OW-2008-0667-1827 J. Steitz

EPA-HQ-OW-2008-0667-1828 L. Lambeth

EPA-HQ-OW-2008-0667-1829 T. and Y. Wootten

EPA-HQ-OW-2008-0667-1830 T. and J. Greenwald
Introduction 

FDMS Document ID First Name Middle 

Name Last Name Organization

EPA-HQ-OW-2008-0667-1831 P. Matejcek

EPA-HQ-OW-2008-0667-1832 J. R. Herron

EPA-HQ-OW-2008-0667-1833 S. Lilley

EPA-HQ-OW-2008-0667-1834 D. Phillips

EPA-HQ-OW-2008-0667-1835 Dr. M. Carlson

EPA-HQ-OW-2008-0667-1836 M. Leven

EPA-HQ-OW-2008-0667-1837 P. Check

EPA-HQ-OW-2008-0667-1838 S. Stevens

EPA-HQ-OW-2008-0667-1839 C. A. Russell

EPA-HQ-OW-2008-0667-1840 J. Wanshel

EPA-HQ-OW-2008-0667-1841 J. Giambrone

EPA-HQ-OW-2008-0667-1842 M. Spilkowitz

EPA-HQ-OW-2008-0667-1843 R. Gentry

EPA-HQ-OW-2008-0667-1844 J. MacLean

EPA-HQ-OW-2008-0667-1845 P. Moctezuma

EPA-HQ-OW-2008-0667-1846 M. Halligan

EPA-HQ-OW-2008-0667-1847 Anonymous

EPA-HQ-OW-2008-0667-1848 M. Culley

EPA-HQ-OW-2008-0667-1849 C. Schosser

EPA-HQ-OW-2008-0667-1850 E. Pimentel

EPA-HQ-OW-2008-0667-1851 G. Camhi

EPA-HQ-OW-2008-0667-1852 W. Southworth

EPA-HQ-OW-2008-0667-1853 R. Kofler

EPA-HQ-OW-2008-0667-1854 D. Graham

EPA-HQ-OW-2008-0667-1855 M. Finklea

EPA-HQ-OW-2008-0667-1856 F. Wade

EPA-HQ-OW-2008-0667-1857 J. Robbins

EPA-HQ-OW-2008-0667-1858 E. Sopoci

EPA-HQ-OW-2008-0667-1859 H. Whitson

EPA-HQ-OW-2008-0667-1860 M. Ajoie-Sanedroff

EPA-HQ-OW-2008-0667-1861 D. Campbell

EPA-HQ-OW-2008-0667-1862 M. Wood

EPA-HQ-OW-2008-0667-1863 D. Waldron

EPA-HQ-OW-2008-0667-1864 S. Ellis

EPA-HQ-OW-2008-0667-1865 M. Michaelis

EPA-HQ-OW-2008-0667-1866 L. Epstein

EPA-HQ-OW-2008-0667-1867 P. Burks

EPA-HQ-OW-2008-0667-1868 A. Dorsch

EPA-HQ-OW-2008-0667-1869 B. Renton
Introduction 

FDMS Document ID First Name Middle 

Name Last Name Organization

EPA-HQ-OW-2008-0667-1870 A. Jenkins

EPA-HQ-OW-2008-0667-1871 M. Bailey

EPA-HQ-OW-2008-0667-1872 D. R. Nelson

EPA-HQ-OW-2008-0667-1873 D. Mitchell

EPA-HQ-OW-2008-0667-1874 C. Daly

EPA-HQ-OW-2008-0667-1875 R. Nydes

EPA-HQ-OW-2008-0667-1876 M. Hiatt

EPA-HQ-OW-2008-0667-1877 M. Johnson

EPA-HQ-OW-2008-0667-1878 D. Greene

EPA-HQ-OW-2008-0667-1879 R. DeLeo

EPA-HQ-OW-2008-0667-1880 L. Wilder

EPA-HQ-OW-2008-0667-1881 G. Crouse

EPA-HQ-OW-2008-0667-1882 D. and S. Pettus

EPA-HQ-OW-2008-0667-1883 C. Buck

EPA-HQ-OW-2008-0667-1884 E. Fraser

EPA-HQ-OW-2008-0667-1885 T. Conroy

EPA-HQ-OW-2008-0667-1886 A. Lum

EPA-HQ-OW-2008-0667-1887 M. Rudinow

EPA-HQ-OW-2008-0667-1888 T. Brainerd

EPA-HQ-OW-2008-0667-1889 A. Genna

EPA-HQ-OW-2008-0667-1890 J. Ross

EPA-HQ-OW-2008-0667-1891 C. A. Berg

EPA-HQ-OW-2008-0667-1892 M. Gallelli

EPA-HQ-OW-2008-0667-1893 C. D. Cutshaw

EPA-HQ-OW-2008-0667-1894 S. Kuster

EPA-HQ-OW-2008-0667-1895 L. Corcoran

EPA-HQ-OW-2008-0667-1896 N. Vesel

EPA-HQ-OW-2008-0667-1897 L. Jaffee

EPA-HQ-OW-2008-0667-1898 J. Maron-Friend

EPA-HQ-OW-2008-0667-1899 R. Siegfried

EPA-HQ-OW-2008-0667-1900 M. Oka

EPA-HQ-OW-2008-0667-1901 R. Robinson

EPA-HQ-OW-2008-0667-1902 C. Bobertz

EPA-HQ-OW-2008-0667-1903 B. Taylor

EPA-HQ-OW-2008-0667-1904 Anonymous

EPA-HQ-OW-2008-0667-1905 M. Moody

EPA-HQ-OW-2008-0667-1906 J. De Hawkhurst

EPA-HQ-OW-2008-0667-1907 L. Torrence

EPA-HQ-OW-2008-0667-1908 M. Sandel
Introduction 

FDMS Document ID First Name Middle 

Name Last Name Organization

EPA-HQ-OW-2008-0667-1909 Michael James Long

EPA-HQ-OW-2008-0667-1910 T. Maresco

EPA-HQ-OW-2008-0667-1911 S. Uribe

EPA-HQ-OW-2008-0667-1912 C. Carey

EPA-HQ-OW-2008-0667-1913 T. Warmbrand

EPA-HQ-OW-2008-0667-1914 R. R. Holt

EPA-HQ-OW-2008-0667-1915 J. Fletcher

EPA-HQ-OW-2008-0667-1916 M. Strawn

EPA-HQ-OW-2008-0667-1917 M. Ditlove

EPA-HQ-OW-2008-0667-1918 R. Leech

EPA-HQ-OW-2008-0667-1919 P. Sweeny

EPA-HQ-OW-2008-0667-1920 J. Colgan-Davis

EPA-HQ-OW-2008-0667-1921 A. Mcneese

EPA-HQ-OW-2008-0667-1922 R. Hosek

EPA-HQ-OW-2008-0667-1923 S. Cardwell

EPA-HQ-OW-2008-0667-1924 M. Bristow

EPA-HQ-OW-2008-0667-1925 M. and A. Roberts

EPA-HQ-OW-2008-0667-1926 G. Collins

EPA-HQ-OW-2008-0667-1927 S. Stoudemire

EPA-HQ-OW-2008-0667-1928 R. Thornhill

EPA-HQ-OW-2008-0667-1929 J. Nappe

EPA-HQ-OW-2008-0667-1930 C. Sample

EPA-HQ-OW-2008-0667-1931 L. Bodiford

EPA-HQ-OW-2008-0667-1932 D. Solomon

EPA-HQ-OW-2008-0667-1933 P. Marriott

EPA-HQ-OW-2008-0667-1934 J. Delgado

EPA-HQ-OW-2008-0667-1935 M. McBride

EPA-HQ-OW-2008-0667-1936 G. Dev

EPA-HQ-OW-2008-0667-1937 D. Filipelli

EPA-HQ-OW-2008-0667-1938 J. Jensen

EPA-HQ-OW-2008-0667-1939 D. Douglas

EPA-HQ-OW-2008-0667-1940 A. Orange

EPA-HQ-OW-2008-0667-1941 L. Burns

EPA-HQ-OW-2008-0667-1942 G. Melzer

EPA-HQ-OW-2008-0667-1943 R. Huelsman

EPA-HQ-OW-2008-0667-1944 C. Dutka

EPA-HQ-OW-2008-0667-1945 P. Rorvik

EPA-HQ-OW-2008-0667-1946 G. Alderette

EPA-HQ-OW-2008-0667-1947 T. Kardos
Introduction 

FDMS Document ID First Name Middle 

Name Last Name Organization

EPA-HQ-OW-2008-0667-1948 D. Mullen

EPA-HQ-OW-2008-0667-1949 P. Chang

EPA-HQ-OW-2008-0667-1950 L. Isbell

EPA-HQ-OW-2008-0667-1951 J. Sorrells

EPA-HQ-OW-2008-0667-1952 E. Balgemann

EPA-HQ-OW-2008-0667-1953 S. Anderson

EPA-HQ-OW-2008-0667-1954 L. Guthrie

EPA-HQ-OW-2008-0667-1955 G. Sindelar

EPA-HQ-OW-2008-0667-1956 M. A. Strom

EPA-HQ-OW-2008-0667-1957 G. Ayres

EPA-HQ-OW-2008-0667-1958 A. Collins

EPA-HQ-OW-2008-0667-1959 E. Lann-Clark

EPA-HQ-OW-2008-0667-1960 Anitra J. Collins Kapstone Paper Corporation

EPA-HQ-OW-2008-0667-1961 State Sen. Kathleen Vinehout Wisconsin State Senate, 31st District

EPA-HQ-OW-2008-0667-1962 Ernie Aschenbach Virginia Department of Game and Inland Fisheries (VA 

DGIF)

EPA-HQ-OW-2008-0667-1963 State Rep. Chris Danou Wisconsin State Assembly, 91st District

EPA-HQ-OW-2008-0667-1964 Debi Durham and Roger Lande Iowa Partnership for Economic Progress/Iowa 

Department of Natural Resources (IA DNR)

EPA-HQ-OW-2008-0667-1965 Kevin M. Brinegar Indiana Chamber of Commerce

EPA-HQ-OW-2008-0667-1966 Bill Cunningham Unions for Jobs and the Environment (UJAE)

EPA-HQ-OW-2008-0667-1967 State Sen. Dale W. Schultz Wisconsin State Senate, District 17

EPA-HQ-OW-2008-0667-1968 D. Holtz-Eakin and S. Baskins

EPA-HQ-OW-2008-0667-1969 Andrew Fahlund American Rivers

EPA-HQ-OW-2008-0667-1970 Mark R. Vickery Texas Commission on Environmental Quality (TCEQ)

EPA-HQ-OW-2008-0667-1971 A. Keesing

EPA-HQ-OW-2008-0667-1972 W. J. Schreier

EPA-HQ-OW-2008-0667-1973 S. Lim

EPA-HQ-OW-2008-0667-1974 R. Downing

EPA-HQ-OW-2008-0667-1975 R. Leibowitz

EPA-HQ-OW-2008-0667-1976 Dr. J. Weinstein

EPA-HQ-OW-2008-0667-1977 J. Townsel

EPA-HQ-OW-2008-0667-1978 M. Alexander

EPA-HQ-OW-2008-0667-1979 A. I. Aurelio

EPA-HQ-OW-2008-0667-1980 P. Johnson

EPA-HQ-OW-2008-0667-1981 S. Krauss

EPA-HQ-OW-2008-0667-1982 H. D. Shumaker

EPA-HQ-OW-2008-0667-1983 P. Ide

EPA-HQ-OW-2008-0667-1984 C. Birch
Introduction 

FDMS Document ID First Name Middle 

Name Last Name Organization

EPA-HQ-OW-2008-0667-1985 R. Grover

EPA-HQ-OW-2008-0667-1986 J. Kozlowski

EPA-HQ-OW-2008-0667-1987 J. Black

EPA-HQ-OW-2008-0667-1988 K. Allison

EPA-HQ-OW-2008-0667-1989 C. VaJames

EPA-HQ-OW-2008-0667-1990 C. Crooke

EPA-HQ-OW-2008-0667-1991 W. Ip

EPA-HQ-OW-2008-0667-1992 M. Monma

EPA-HQ-OW-2008-0667-1993 D., D., D. and B. Poole

EPA-HQ-OW-2008-0667-1994 E. Omalley

EPA-HQ-OW-2008-0667-1995 D. Welsch

EPA-HQ-OW-2008-0667-1996 K. Arellanes

EPA-HQ-OW-2008-0667-1997 D. C. Wilson

EPA-HQ-OW-2008-0667-1998 C. Burns

EPA-HQ-OW-2008-0667-1999 M. Rae

EPA-HQ-OW-2008-0667-2000 T. Frank

EPA-HQ-OW-2008-0667-2001 Dr. K. Gunter

EPA-HQ-OW-2008-0667-2002 P. Mccollim

EPA-HQ-OW-2008-0667-2003 J. K. Hedges

EPA-HQ-OW-2008-0667-2004 Garry A. Brown and Jeanne M. Fox National Association of Regulatory Utility Commissioners 

(NARUC)

EPA-HQ-OW-2008-0667-2005 Cindy B. Miller Florida Public Service Commission (PSC)

EPA-HQ-OW-2008-0667-2006 J. Avery

EPA-HQ-OW-2008-0667-2007 G. Spencer

EPA-HQ-OW-2008-0667-2008 Dr. J. Tullis

EPA-HQ-OW-2008-0667-2009 A. Almirola

EPA-HQ-OW-2008-0667-2010 M. O'Brien

EPA-HQ-OW-2008-0667-2011 M. Thorne

EPA-HQ-OW-2008-0667-2012 P. Beattie

EPA-HQ-OW-2008-0667-2013 B. Gorman

EPA-HQ-OW-2008-0667-2014 J. Garibaldi

EPA-HQ-OW-2008-0667-2015 S. Michael

EPA-HQ-OW-2008-0667-2016 P. Jones

EPA-HQ-OW-2008-0667-2017 Joe Geever Surfrider Foundation

EPA-HQ-OW-2008-0667-2018 D. Shanaman

EPA-HQ-OW-2008-0667-2019 A. Wasgatt

EPA-HQ-OW-2008-0667-2020 Ingrid Setzler Kansas City Board of Public Utilities (KCBPU)

EPA-HQ-OW-2008-0667-2021 K. Benzel

EPA-HQ-OW-2008-0667-2022 Dr. G. Crouse
Introduction 

FDMS Document ID First Name Middle 

Name Last Name Organization

EPA-HQ-OW-2008-0667-2023 C. Ridenour

EPA-HQ-OW-2008-0667-2024 M. Bennett

EPA-HQ-OW-2008-0667-2025 Dr. J. Unruh

EPA-HQ-OW-2008-0667-2026 T. Spencer

EPA-HQ-OW-2008-0667-2027 M. Martin

EPA-HQ-OW-2008-0667-2028 Dr. D. Kramer

EPA-HQ-OW-2008-0667-2029 I. Shaw

EPA-HQ-OW-2008-0667-2030 M. Dzindzeleta

EPA-HQ-OW-2008-0667-2031 M. Miller

EPA-HQ-OW-2008-0667-2032 L. St. John

EPA-HQ-OW-2008-0667-2033 L. Robin

EPA-HQ-OW-2008-0667-2034 J. Laiti

EPA-HQ-OW-2008-0667-2035 S. Wiebe

EPA-HQ-OW-2008-0667-2036 C. Dukes Scott South Carolina Office of Regulatory Staff (ORS) (Duke 

Energy)

EPA-HQ-OW-2008-0667-2037 R. Dimatteo

EPA-HQ-OW-2008-0667-2038 M. Scott

EPA-HQ-OW-2008-0667-2039 A. Payne

EPA-HQ-OW-2008-0667-2040 T. B. Silverman

EPA-HQ-OW-2008-0667-2041 S. Lannin

EPA-HQ-OW-2008-0667-2042 B. P. Gallagher

EPA-HQ-OW-2008-0667-2043 L. Godwin

EPA-HQ-OW-2008-0667-2044 State Sen. Paul G. Campbell, Jr. South Carolina State Senate (Duke Energy)

EPA-HQ-OW-2008-0667-2045 Robert M. Hitt III South Carolina Department of Commerce (Duke Energy)

EPA-HQ-OW-2008-0667-2046 James E. Earl Severstal Dearborn, LLC

EPA-HQ-OW-2008-0667-2047 James Thate Delta-Montrose Electric Association

EPA-HQ-OW-2008-0667-2048 Stephen K. Davis Association of Illinois Electrical Cooperatives (AIEC)

EPA-HQ-OW-2008-0667-2049 Michael Ralston Iowa Association of Business and Industry (ABI)

EPA-HQ-OW-2008-0667-2050 Leonard F. Hopkins Southern Illinois Power Cooperative (SIPC)

EPA-HQ-OW-2008-0667-2051 James F. Stine National Rural Electric Cooperative Association (NRECA)

EPA-HQ-OW-2008-0667-2052 Lewis F. Gossett South Carolina Manufacturers Alliance (SCMA)

EPA-HQ-OW-2008-0667-2053 State Rep. Chris Danou Wisconsin State Assembly, 91st District

EPA-HQ-OW-2008-0667-2054 Terry M. Hogan Wabash Valley Power Association (WVPA)

EPA-HQ-OW-2008-0667-2056 R. Stambaugh

EPA-HQ-OW-2008-0667-2057 N. H. Gronlund

EPA-HQ-OW-2008-0667-2058 J. Tatarczuk

EPA-HQ-OW-2008-0667-2059 J. Archuleta

EPA-HQ-OW-2008-0667-2060 H. Blechar

EPA-HQ-OW-2008-0667-2061 J. Wheeler
Introduction 

FDMS Document ID First Name Middle 

Name Last Name Organization

EPA-HQ-OW-2008-0667-2062 T. Harris

EPA-HQ-OW-2008-0667-2063 Susan L. Sylvester Wisconsin Department of Natural Resources (WI DNR)

EPA-HQ-OW-2008-0667-2064 R. Bloom

EPA-HQ-OW-2008-0667-2065 State Sen. Mary Jo White, et al. Pennsylvania State Senate and State House of 

Representatives

EPA-HQ-OW-2008-0667-2066 April Ingle Georgia River Network

EPA-HQ-OW-2008-0667-2067 State Sen. David T. Daniels Ohio State Senate, 17th District

EPA-HQ-OW-2008-0667-2068 Gov. Mary Fallin State of Oklahoma

EPA-HQ-OW-2008-0667-2069 State Sen. Terry Moulton Wisconsin State Senate, 23rd District

EPA-HQ-OW-2008-0667-2070 John W. Dwyer Lignite Energy Council (LEC)

EPA-HQ-OW-2008-0667-2071 State Rep. Edward Brooks Wisconsin State Assembly, 50th District

EPA-HQ-OW-2008-0667-2072 State Rep. Bill Sandifer South Carolina State House of Representatives

EPA-HQ-OW-2008-0667-2073 Gary Hanson and Chris Nelson South Dakota Public Utilities Commission

EPA-HQ-OW-2008-0667-2074 Mass Comment 

Campaign

Unknown

EPA-HQ-OW-2008-0667-2075 Mass Comment 

Campaign

National Wildlife Federation Action Fund (NWF)

EPA-HQ-OW-2008-0667-2076 C. Lish

EPA-HQ-OW-2008-0667-2077 M. Bushnell

EPA-HQ-OW-2008-0667-2078 Nicholas A. Brown Southwest Power Pool, Inc. (SPP)

EPA-HQ-OW-2008-0667-2079 Jeff A. McNelly Anthracite Region Independent Power Producers 

Association (ARIPPA)

EPA-HQ-OW-2008-0667-2080 Rich Cogen Ohio River Foundation

EPA-HQ-OW-2008-0667-2081 Bill Cunningham Unions for Jobs and the Environment (UJAE)

EPA-HQ-OW-2008-0667-2082 Michael Bradley Clean Energy Group

EPA-HQ-OW-2008-0667-2083 J. Evan

EPA-HQ-OW-2008-0667-2084 K. Wright

EPA-HQ-OW-2008-0667-2085 A. Acker

EPA-HQ-OW-2008-0667-2086 L. Greenawalt

EPA-HQ-OW-2008-0667-2087 C. Johnson

EPA-HQ-OW-2008-0667-2088 M. Pilley

EPA-HQ-OW-2008-0667-2089 M. Huddleston

EPA-HQ-OW-2008-0667-2090 M. Strawn

EPA-HQ-OW-2008-0667-2091 A. Pahl

EPA-HQ-OW-2008-0667-2092 F. Lamberts

EPA-HQ-OW-2008-0667-2093 W. Johnson

EPA-HQ-OW-2008-0667-2094 S. Reid

EPA-HQ-OW-2008-0667-2095 E. Thorpe

EPA-HQ-OW-2008-0667-2096 T. Bubul
Introduction 

FDMS Document ID First Name Middle 

Name Last Name Organization

EPA-HQ-OW-2008-0667-2097 K. Simmons

EPA-HQ-OW-2008-0667-2098 C. Ringgold

EPA-HQ-OW-2008-0667-2099 P. Nolte

EPA-HQ-OW-2008-0667-2100 R. Vandehey

EPA-HQ-OW-2008-0667-2101 S. Waldon

EPA-HQ-OW-2008-0667-2102 David K. Perkins SABIC Innovative Plastics

EPA-HQ-OW-2008-0667-2103 State Rep. Scott Suder Wisconsin State Assembly, 69th District

EPA-HQ-OW-2008-0667-2104 Gov. Scott Walker State of Wisconsin

EPA-HQ-OW-2008-0667-2105 State Sen. Pam 

Galloway

and State Rep. Mary 

Williams

Wisconsin State Senate, 29th District and Wisconsin 

State Assembly, 87th District

EPA-HQ-OW-2008-0667-2106 Robert F. Powelson, et al Pennsylvania Public Utility Commission

EPA-HQ-OW-2008-0667-2107 Mass Comment 

Campaign

Unknown

EPA-HQ-OW-2008-0667-2108 Scott Davis Arizona Public Service Company (APS)

EPA-HQ-OW-2008-0667-2109 Scott J. Nally Ohio Environmental Protection Agency (EPA)

EPA-HQ-OW-2008-0667-2110 Stephen Minick Texas Association of Business

EPA-HQ-OW-2008-0667-2111 Ron Flax-Davidson Hudson River Sloop Clearwater, Inc.

EPA-HQ-OW-2008-0667-2112 Jeff A. McNelly Anthracite Region Independent Power Producers 

Association (ARIPPA)

EPA-HQ-OW-2008-0667-2113 N. Spitzfaden

EPA-HQ-OW-2008-0667-2114 Willie R. Taylor United States Department of the Interior (DOI)

EPA-HQ-OW-2008-0667-2115 State Sen. Bob Rucho North Carolina State Senate

EPA-HQ-OW-2008-0667-2116 State Sen. Dan Sparks Minnesota State Senate, District 27, 

EPA-HQ-OW-2008-0667-2117 M. A. Link

EPA-HQ-OW-2008-0667-2118 Trent A. Dougherty and Rachel L. Herbst Ohio Environmental Council (OEC)

EPA-HQ-OW-2008-0667-2119 James S. Alves Florida Electric Power Coordinating Group, Inc. (FCG)

EPA-HQ-OW-2008-0667-2120 State Sen. Bruce Caswell Michigan State Senate, District 16

EPA-HQ-OW-2008-0667-2121 Patrick Bennett Indiana Manufacturers Association (IMA)

EPA-HQ-OW-2008-0667-2122 J. Capozzelli

EPA-HQ-OW-2008-0667-2123 Angila M. Retherford Vectren Corporation

EPA-HQ-OW-2008-0667-2124 Nysa L. Hogue Indianapolis Power and Light Company (IPL)

EPA-HQ-OW-2008-0667-2125 J. R. DeFriece

EPA-HQ-OW-2008-0667-2126 Craig Bressan Prairie State Generating Company LLC (PSGC)

EPA-HQ-OW-2008-0667-2127 State Sen. Julie Rosen and State Sen. Jeremy 

Miller

Minnesota State Senate, Districts 24 and 31

EPA-HQ-OW-2008-0667-2128 State Rep. Nan Baker Ohio State House of Representatives, District 16

EPA-HQ-OW-2008-0667-2129 D. Canton

EPA-HQ-OW-2008-0667-2130 C. Laieski

EPA-HQ-OW-2008-0667-2131 B. Leonard
Introduction 

FDMS Document ID First Name Middle 

Name Last Name Organization

EPA-HQ-OW-2008-0667-2132 Otis B. Rawl, Jr. South Carolina Chamber of Commerce

EPA-HQ-OW-2008-0667-2134 Anthony N. Jacobs International Brotherhood of Boilermakers, Iron Ship 

Builders, Blacksmiths, Forgers and Helpers, AFL-CIO 

(Boilermakers Union)

EPA-HQ-OW-2008-0667-2135 Steven A. Thompson Oklahoma Department of Enviromental Quality (OK DEQ)

EPA-HQ-OW-2008-0667-2136 State Sen. John Proos, et al. Michigan State Senate

EPA-HQ-OW-2008-0667-2137 State Rep. Nelson L. Hardwick South Carolina State House of Representatives

EPA-HQ-OW-2008-0667-2138 Gov. Haley Barbour State of Mississippi

EPA-HQ-OW-2008-0667-2139 William L. Kovacs United States Chamber of Commerce

EPA-HQ-OW-2008-0667-2140 Ronald R. Cox Hawaiian Electric Company

EPA-HQ-OW-2008-0667-2141 Jon A. Finlinson Intermountain Power Service Corporation (IPSC)

EPA-HQ-OW-2008-0667-2142 Patrick O. Loughlin Buckeye Power, Inc.

EPA-HQ-OW-2008-0667-2143 Frank Prager Xcel Energy, Inc.

EPA-HQ-OW-2008-0667-2144 Bruce W. Ramme We Energies

EPA-HQ-OW-2008-0667-2145 Douglas P. Mauro Rockland Capital Cape May Holdings (RCCMH)

EPA-HQ-OW-2008-0667-2146 Coleen H. Sullins North Carolina Department of Environment and Natural 

Resources (NCDENR)

EPA-HQ-OW-2008-0667-2147 Todd A. Snitchler Ohio Public Utilities Commission (PUC)

EPA-HQ-OW-2008-0667-2148 Anthony N. Jacobs International Brotherhood of Boilermakers, Iron Ship 

Builders, Blacksmiths, Forgers and Helpers, AFL-CIO 

(Boilermakers Union)

EPA-HQ-OW-2008-0667-2149 Walter L. Baker Association of State and Interstate Water Pollution 

Control Administrators (ASIWPCA)

EPA-HQ-OW-2008-0667-2150 Scott Newberry Florida Keys Electric Cooperative Association Inc (FKEC)

EPA-HQ-OW-2008-0667-2151 Randall R. LaBauve NextEra Energy

EPA-HQ-OW-2008-0667-2152 Thomas L. Hernandez Tampa Electric Company (TEC)

EPA-HQ-OW-2008-0667-2153 Pilar Patterson New Jersey Department of Environmental Protection 

(NJDEP)

EPA-HQ-OW-2008-0667-2154 JoAnne Rau The Dayton Power and Light Company (DP&L)

EPA-HQ-OW-2008-0667-2155 Mark A. Shepherd Topaz Power Holding, LLC (TPH)

EPA-HQ-OW-2008-0667-2156 Thomas R. Kuhn Edison Electric Institute (EEI)

EPA-HQ-OW-2008-0667-2157 Hal Bozarth Chemistry Council of New Jersey (CCNJ)

EPA-HQ-OW-2008-0667-2158 Robert D. Teetz National Grid

EPA-HQ-OW-2008-0667-2159 C. Lish

EPA-HQ-OW-2008-0667-2160 Kevin Wanttaja Salt River Project (SRP)

EPA-HQ-OW-2008-0667-2161 Jay Hudson Santee Cooper

EPA-HQ-OW-2008-0667-2162 Keith Stephens PowerSouth Energy Cooperative

EPA-HQ-OW-2008-0667-2163 Scott Wolff Honeywell International, Inc.

EPA-HQ-OW-2008-0667-2164 State Rep. Lee Nerison Wisconsin State Assembly, 96th District
Introduction 

FDMS Document ID First Name Middle 

Name Last Name Organization

EPA-HQ-OW-2008-0667-2165 Julie Meka Carter Arizona-New Mexico Chapter of the American Fisheries 

Society (AZ-NM Chapter)

EPA-HQ-OW-2008-0667-2166 John T. Graves Minnkota Power Cooperative Inc.

EPA-HQ-OW-2008-0667-2167 George Bakun ConocoPhillips Company, Bayway Refinery

EPA-HQ-OW-2008-0667-2168 Jim Donofrio and Jim Hutchinson, Jr Recreational Fishing Alliance (RFA) and the New York 

Sportfishing Federation (NYSF)

EPA-HQ-OW-2008-0667-2169 S. L. Dannhardt STP Nuclear Operating Company (STPNOC)

EPA-HQ-OW-2008-0667-2170 Larry J. Koshire Rochester Public Utilities (RPU)

EPA-HQ-OW-2008-0667-2171 Russell Frye Cooling Water Intake Structure Coalition

EPA-HQ-OW-2008-0667-2172 Edwin D. Hill International Brotherhood of Electrical Workers (IBEW)

EPA-HQ-OW-2008-0667-2173 Sam L. Phillips Louisiana Department of Environmental Quality (LDEQ)

EPA-HQ-OW-2008-0667-2174 Nancy A. Evans PPL Corporation

EPA-HQ-OW-2008-0667-2175 Terry P. Jensky Wisconsin Public Service Corporation (WPSC)

EPA-HQ-OW-2008-0667-2176 Maureen Gannon PNM Resources (PMNR)

EPA-HQ-OW-2008-0667-2177 Linda Whelan Dynegy Inc.

EPA-HQ-OW-2008-0667-2178 Shirley M. Ruffin SCANA Corporation (SCANA)

EPA-HQ-OW-2008-0667-2179 Henry Eby Lower Colorado River Authority (LCRA)

EPA-HQ-OW-2008-0667-2180 Stephen Donovan Taunton Municipal Lighting Plant (TMLP)

EPA-HQ-OW-2008-0667-2181 Pamela F. Faggert Dominion Resources

EPA-HQ-OW-2008-0667-2182 Bruce Parker Electric Energy, Inc. (EEI)

EPA-HQ-OW-2008-0667-2183 David Friedman National Petrochemical and Refiners Association (NPRA)

EPA-HQ-OW-2008-0667-2184 John W. Myers Tennessee Valley Authority (TVA)

EPA-HQ-OW-2008-0667-2185 Brian H. Moeck The Large Public Power Council (LPPC)

EPA-HQ-OW-2008-0667-2186 Jerry Bonanno and William Skaff Nuclear Energy Institute (NEI)

EPA-HQ-OW-2008-0667-2187 Gov. Matthew H. Mead State of Wyoming

EPA-HQ-OW-2008-0667-2188 James Murphy National Wildlife Federation (NWF), et al.

EPA-HQ-OW-2008-0667-2189 Douglas J. Fulle Oglethorpe Power Corporation

EPA-HQ-OW-2008-0667-2190 Chris M. Hobson Southern Company

EPA-HQ-OW-2008-0667-2191 Jeffrey P. deBessonet South Carolina Department of Health and Environmental 

Control (SCDHEC)

EPA-HQ-OW-2008-0667-2192 Eric B. Svenson, Jr. PSEG Services Corporation

EPA-HQ-OW-2008-0667-2193 John Reese Astoria Generating Company (AGC)

EPA-HQ-OW-2008-0667-2194 Henry T. Graham Louisiana Chemical Association (LCA) (Kean Miller LLP)

EPA-HQ-OW-2008-0667-2195 David M. Fraley City Utilities of Springfield, Missouri (CU)

EPA-HQ-OW-2008-0667-2196 Michael Brom PCS Nitrogen Fertilizer, L.P.

EPA-HQ-OW-2008-0667-2197 Roger E. Claff American Petroleum Institute (API)

EPA-HQ-OW-2008-0667-2198 Ron Shipman Georgia Power Company

EPA-HQ-OW-2008-0667-2199 Erik Silvola Great River Energy (GRE)

EPA-HQ-OW-2008-0667-2200 Douglas A. Dixon Electric Power Research Institute (EPRI)
Introduction 

FDMS Document ID First Name Middle 

Name Last Name Organization

EPA-HQ-OW-2008-0667-2201 Justin G. Johnson Vermont Department of Environmental Conservation (VT 

DEC)

EPA-HQ-OW-2008-0667-2202 Shawn Seaman and Edwal Stone Maryland Department of Natural Resources and 

Department of the Environment (MD DNR and DOE)

EPA-HQ-OW-2008-0667-2203 Gavin J. Donohue Independent Power Producers of New York, Inc. (IPPNY)

EPA-HQ-OW-2008-0667-2204 William C. Herz The Fertilizer Institute (TFI)

EPA-HQ-OW-2008-0667-2205 Thomas Howard California State Water Resources Control Board (CA 

SWRCB)

EPA-HQ-OW-2008-0667-2206 Douglas W. Craven Little Traverse Bay Bands of Odawa Indians (LTBB)

EPA-HQ-OW-2008-0667-2207 Nancy M. Clark American Chemistry Council (ACC)

EPA-HQ-OW-2008-0667-2208 Jeffrey S. Longsworth Alcoa, Inc. (Barnes & Thornburg LLP)

EPA-HQ-OW-2008-0667-2209 Patricia D. Horn and Kenneth E. Raymond Oklahoma Gas and Electric Company (OG&E)

EPA-HQ-OW-2008-0667-2210 James N. Christman Utility Water Act Group (UWAG) (Hunton and Williams 

LLP)

EPA-HQ-OW-2008-0667-2211 Cathy S. Woolums MidAmerican Energy Holdings Company

EPA-HQ-OW-2008-0667-2212 John R. Westendorf Occidental Chemical Corporation (OxyChem)

EPA-HQ-OW-2008-0667-2213 Bobby Byers Texas Chapter of the Coastal Conservation Association 

(CCA Texas)

EPA-HQ-OW-2008-0667-2214 Patrick O. Loughlin Buckeye Power, Inc.

EPA-HQ-OW-2008-0667-2215 Eric Myers and Nathan Craig Duke Energy Business Services, LLC

EPA-HQ-OW-2008-0667-2216 Michael Bradley Clean Energy Group

EPA-HQ-OW-2008-0667-2217 William J. Donohue Exelon Business Services Company

EPA-HQ-OW-2008-0667-2218 Maya K. van Rossum Delaware Riverkeeper Network (DRN)

EPA-HQ-OW-2008-0667-2219 E. Chase

EPA-HQ-OW-2008-0667-2220 Gregory W. Baise Illinois Manufacturer's Association (IMA)

EPA-HQ-OW-2008-0667-2221 Susanne M. Herald GE Aviation

EPA-HQ-OW-2008-0667-2222 Matthew Prine Indiana Utility Shareholders Association

EPA-HQ-OW-2008-0667-2223 Steve List NewPage Corporation

EPA-HQ-OW-2008-0667-2224 Mark A. Hartle The Pennsylvania Fish and Boat Commission (PFBC)

EPA-HQ-OW-2008-0667-2225 Richard T. Metcalf Louisiana (LA) Mid-Continent Oil and Gas Association 

(LMOGA)

EPA-HQ-OW-2008-0667-2226 Douglas P. Mauro Rockland Capital Cape May Holdings (RCCMH)

EPA-HQ-OW-2008-0667-2227 Gov. Beverly Eaves Perdue State of North Carolina

EPA-HQ-OW-2008-0667-2228 Richard G. Burud Nobles Cooperative Electric

EPA-HQ-OW-2008-0667-2229 Abbie Krebsbach Montana-Dakota Utilities Co.

EPA-HQ-OW-2008-0667-2230 MaryAnn J. Otter Morro Coast Audubon Society

EPA-HQ-OW-2008-0667-2231 Fred T. Harnack United States Steel Corporation (USS)

EPA-HQ-OW-2008-0667-2232 William Creal Michigan Department of Environmental Quality (MDEQ)

EPA-HQ-OW-2008-0667-2233 Jared Morrison Westar Energy, Inc.
Introduction 

FDMS Document ID First Name Middle 

Name Last Name Organization

EPA-HQ-OW-2008-0667-2234 Terry Graumann Otter Tail Power Company

EPA-HQ-OW-2008-0667-2235 Dustin McDaniel Arkansas Attorney General, et al.

EPA-HQ-OW-2008-0667-2236 Robert Underwood Delaware Department of Natural Resources and 

Environmental Control (DNREC)

EPA-HQ-OW-2008-0667-2237 Douglas R. Kopp Alliant Energy Corporate Services, Inc.

EPA-HQ-OW-2008-0667-2238 Alan R. Wood American Electric Power, Inc. (AEP)

EPA-HQ-OW-2008-0667-2239 Matthew J. Dunn Illinois Attorney General's Office

EPA-HQ-OW-2008-0667-2240 Orjiakor N. Isiogu, et al. Michigan Public Service Commission

EPA-HQ-OW-2008-0667-2241 Pamela F. Faggert Dominion Resources

EPA-HQ-OW-2008-0667-2242 Jerry Bonanno and William Skaff Nuclear Energy Institute (NEI)

EPA-HQ-OW-2008-0667-2243 Steven L. Kline Pacific Gas and Electric Company (PG&E)

EPA-HQ-OW-2008-0667-2244 Caroline Choi Progress Energy

EPA-HQ-OW-2008-0667-2245 Basil G. Constantelos Midwest Generation, Edison Mission Energy, LLC

EPA-HQ-OW-2008-0667-2246 Mark P. Thomasson Florida Department of Environmental Protection (FL DEP)

EPA-HQ-OW-2008-0667-2247 Ann W. McIver Citizens Energy Group

EPA-HQ-OW-2008-0667-2248 Michael L. Krancer Pennsylvania Department of Environmental Protection 

(DEP)

EPA-HQ-OW-2008-0667-2249 Holly Propst Western Business Roundtable

EPA-HQ-OW-2008-0667-2250 Joe L. Citta, Jr. Nebraska Public Power District

EPA-HQ-OW-2008-0667-2251 James R. Korpi Cliffs Natural Resources Inc.

EPA-HQ-OW-2008-0667-2252 Ram Madugula ASME Knowledge and Community Power Division

EPA-HQ-OW-2008-0667-2253 Eric Miller and Shane Beck MBC Applied Environmental Sciences (MBC)

EPA-HQ-OW-2008-0667-2254 Jerry Purvis East Kentucky Power Cooperative (EKPC)

EPA-HQ-OW-2008-0667-2255 Jeannine M. Hammer FirstEnergy Corp. (FE)

EPA-HQ-OW-2008-0667-2256 Hanneke Counts Eastman Chemical Company

EPA-HQ-OW-2008-0667-2257 Steven C. Whitworth Ameren Corporation

EPA-HQ-OW-2008-0667-2258 John Humes Hoosier Energy REC, Inc.

EPA-HQ-OW-2008-0667-2259 Dean C. DeLorey The Amalgamated Sugar Company LLC (TASCO)

EPA-HQ-OW-2008-0667-2260 Christopher A. Amato New York State Department of Environmental 

Conservation (NYSDEC)

EPA-HQ-OW-2008-0667-2261 Donald R. Schregardus Department of The Navy, Department of Defense (DOD)

EPA-HQ-OW-2008-0667-2262 Daniel C. Esty Connecticut Department of Energy and Environmental 

Protection (CT DEEP)

EPA-HQ-OW-2008-0667-2263 Donald Neal Calpine Corporation

EPA-HQ-OW-2008-0667-2264 Faith E. Bugel and Thomas Cmar The Alliance for the Great Lakes, et al. (Environmental 

Law & Policy Center and Natural Resources Defense 

Council)

EPA-HQ-OW-2008-0667-2265 Paul A. Yost National Association of Manufacturers (NAM)

EPA-HQ-OW-2008-0667-2266 Russ Baker Omaha Public Power District (OPPD)
Introduction 

FDMS Document ID First Name Middle 

Name Last Name Organization

EPA-HQ-OW-2008-0667-2267 Roger Caiazza Environmental Energy Alliance of New York, LLC

EPA-HQ-OW-2008-0667-2268 Verne Shortell NRG Energy, Inc.

EPA-HQ-OW-2008-0667-2269 Robert D. Bessette Council of Industrial Boiler Owners (CIBO)

EPA-HQ-OW-2008-0667-2270 Glenda L. Dean Alabama Department of Environmental Management 

(ADEM)

EPA-HQ-OW-2008-0667-2271 Thomas E. DuPlessis NOVA Chemicals Inc. (NOVA)

EPA-HQ-OW-2008-0667-2272 Traylor Champion Georgia-Pacific LLC (GP)

EPA-HQ-OW-2008-0667-2273 E. Mitchell Roob, Jr. Indiana Economic Development Corporation (IEDC)

EPA-HQ-OW-2008-0667-2274 Michael G. Cashin Minnesota Power (ALLETE)

EPA-HQ-OW-2008-0667-2275 Mike Godfrey Alabama Power Company

EPA-HQ-OW-2008-0667-2276 Mark J. Sedlacek Los Angeles Department of Water and Power (LADWP)

EPA-HQ-OW-2008-0667-2277 Berdell Knowles JEA

EPA-HQ-OW-2008-0667-2278 John D. Free Alabama Public Service Commission (APSC)

EPA-HQ-OW-2008-0667-2279 Claire M. Olson Basin Electric Power Cooperative

EPA-HQ-OW-2008-0667-2280 Gov. Eddie Baza Calvo Island of Guam

EPA-HQ-OW-2008-0667-2281 Bobby Byers Texas Chapter of the Coastal Conservation Association 

(CCA Texas)

EPA-HQ-OW-2008-0667-2282 John Bentine and April Bott American Municipal Power, Inc. (AMP)

EPA-HQ-OW-2008-0667-2283 Jon Barrett IPR-GDF SUEZ North America, Generation

EPA-HQ-OW-2008-0667-2284 Mindy Lubber Ceres

EPA-HQ-OW-2008-0667-2285 Bob Martin New Jersey Department of Environmental Protection 

(NJDEP)

EPA-HQ-OW-2008-0667-2286 Elizabeth Wheeler Clean Wisconsin

EPA-HQ-OW-2008-0667-2287 Douglas R. Larson Dakota Electric Association (DEA)

EPA-HQ-OW-2008-0667-2288 Patricia D. Horn and Kenneth E. Raymond Oklahoma Gas and Electric Company (OG&E)

EPA-HQ-OW-2008-0667-2289 Gov. Gary R. Herbert, et al. State of Utah, et al.

EPA-HQ-OW-2008-0667-2290 Louisa Eclarinal CPS Energy

EPA-HQ-OW-2008-0667-2291 Maria Valdez The Dow Chemical Company

EPA-HQ-OW-2008-0667-2292 Thomas C. Perry National Mining Association (NMA)

EPA-HQ-OW-2008-0667-2293 Adam H. Putnam Florida Department of Agriculture and Consumer Services

EPA-HQ-OW-2008-0667-2294 Mike Godfrey Alabama Power Company (Balch & Bingham LLP)

EPA-HQ-OW-2008-0667-2295 Jolene M. Thompson American Municipal Power, Inc. (AMP)

EPA-HQ-OW-2008-0667-2296 Mass Comment 

Campaign

Food & Water Watch

EPA-HQ-OW-2008-0667-2297 William C. Herz The Fertilizer Institute (TFI)

EPA-HQ-OW-2008-0667-2298 John Fainter, Jr. Association of Electric Companies of Texas (AECT)

EPA-HQ-OW-2008-0667-2299 Bill Matthews Cleco Corporation

EPA-HQ-OW-2008-0667-2300 William J. Skrabak City of Alexandria, Virginia

EPA-HQ-OW-2008-0667-2301 Gov. Eddie Baza Calvo Island of Guam
Introduction 

FDMS Document ID First Name Middle 

Name Last Name Organization

EPA-HQ-OW-2008-0667-2302 Jim Weeks Michigan Municipal Electric Association (MMEA)

EPA-HQ-OW-2008-0667-2303 Nicholas M. Demik Northern Indiana Public Service Company (NIPSCO)

EPA-HQ-OW-2008-0667-2304 John A. Gulvas Consumers Energy

EPA-HQ-OW-2008-0667-2305 Nilaksh Kothari Manitowoc Public Utilities (MPU)

EPA-HQ-OW-2008-0667-2306 D. Artemis

EPA-HQ-OW-2008-0667-2307 W. Richards

EPA-HQ-OW-2008-0667-2308 R. L. Ramsay

EPA-HQ-OW-2008-0667-2309 N. Caswell

EPA-HQ-OW-2008-0667-2310 K. Manning

EPA-HQ-OW-2008-0667-2311 Edward R. Griegel Sunbury Generation LP

EPA-HQ-OW-2008-0667-2312 Theresa Pugh American Public Power Association (APPA)

EPA-HQ-OW-2008-0667-2313 Michael L. Krancer Pennsylvania Department of Environmental Protection 

(DEP)

EPA-HQ-OW-2008-0667-2314 Shawn Glacken Luminant

EPA-HQ-OW-2008-0667-2315 Edward R. Griegel Sunbury Generation LP

EPA-HQ-OW-2008-0667-2316 William J. Schulte Delaware Riverkeeper, et al. (Eastern Environmental Law 

Center (EELC))

EPA-HQ-OW-2008-0667-2317 G. Girard

EPA-HQ-OW-2008-0667-2318 J. Poirier

EPA-HQ-OW-2008-0667-2319 L. Fronce and T. Hall

EPA-HQ-OW-2008-0667-2320 L. Fidell

EPA-HQ-OW-2008-0667-2321 L. Barrett

EPA-HQ-OW-2008-0667-2322 J. Schriebman

EPA-HQ-OW-2008-0667-2323 P. Haggard

EPA-HQ-OW-2008-0667-2324 Dr. D. Sain

EPA-HQ-OW-2008-0667-2325 Dr. J. G. Garey

EPA-HQ-OW-2008-0667-2326 C. Krajnyk

EPA-HQ-OW-2008-0667-2327 Mark Zion Texas Public Power Association (TPPA)

EPA-HQ-OW-2008-0667-2328 Michael A. Snyder Water Task Force of the Ohio Utility Group (Shumaker, 

Loop & Kendrick, LLP)

EPA-HQ-OW-2008-0667-2329 R. Atanasoff

EPA-HQ-OW-2008-0667-2330 Paul J. Allen and Steven L. Miller Constellation Energy Group, Inc. (CEG)/Constellation 

Energy Nuclear Group, LLC (CENG)

EPA-HQ-OW-2008-0667-2331 Scott Terhune C-Water Technologies

EPA-HQ-OW-2008-0667-2332 April R. Bott City of Hamilton (Bott Law Group LLC)

EPA-HQ-OW-2008-0667-2333 D. Giordano

EPA-HQ-OW-2008-0667-2334 B. Smith

EPA-HQ-OW-2008-0667-2335 L. Sturm

EPA-HQ-OW-2008-0667-2336 William Schulte Jersey City Environmental Commission
Introduction 

FDMS Document ID First Name Middle 

Name Last Name Organization

EPA-HQ-OW-2008-0667-2337 Bob Martin New Jersey Department of Environmental Protection 

(NJDEP)

EPA-HQ-OW-2008-0667-2338 S. Pena

EPA-HQ-OW-2008-0667-2339 B. Bean

EPA-HQ-OW-2008-0667-2340 Corey E. Olsen

EPA-HQ-OW-2008-0667-2341 H. Wallof

EPA-HQ-OW-2008-0667-2342 D. Chary

EPA-HQ-OW-2008-0667-2343 D. Cutter

EPA-HQ-OW-2008-0667-2344 H. Sellers

EPA-HQ-OW-2008-0667-2345 J. Robinson

EPA-HQ-OW-2008-0667-2346 M. Kissinger

EPA-HQ-OW-2008-0667-2347 Elise N. Zoli Entergy Corporation (Goodwin Procter LLP)

EPA-HQ-OW-2008-0667-2348 Dr. R. Ross

EPA-HQ-OW-2008-0667-2349 H. Carr

EPA-HQ-OW-2008-0667-2350 A. Ambler

EPA-HQ-OW-2008-0667-2351 G. Adams

EPA-HQ-OW-2008-0667-2352 E. Reiter

EPA-HQ-OW-2008-0667-2353 K. Wild

EPA-HQ-OW-2008-0667-2354 B. Jones

EPA-HQ-OW-2008-0667-2355 J. McCarthy

EPA-HQ-OW-2008-0667-2356 Paul M. Ling Kansas City Power & Light Company (KCP&L)

EPA-HQ-OW-2008-0667-2357 H. Smith

EPA-HQ-OW-2008-0667-2358 D. Hodul

EPA-HQ-OW-2008-0667-2359 P. Baker

EPA-HQ-OW-2008-0667-2360 M. Saville

EPA-HQ-OW-2008-0667-2361 B. Grant

EPA-HQ-OW-2008-0667-2362 M. Brownlee

EPA-HQ-OW-2008-0667-2363 Charles F. Brown

EPA-HQ-OW-2008-0667-2364 N. Paradiso

EPA-HQ-OW-2008-0667-2365 M. Sayre

EPA-HQ-OW-2008-0667-2366 B. Bean

EPA-HQ-OW-2008-0667-2367 R. Flower

EPA-HQ-OW-2008-0667-2368 V. and B. Ulmer

EPA-HQ-OW-2008-0667-2369 R. Briand

EPA-HQ-OW-2008-0667-2370 M. Deradune

EPA-HQ-OW-2008-0667-2371 C. Willis

EPA-HQ-OW-2008-0667-2372 Tom Caprio

EPA-HQ-OW-2008-0667-2373 R. Smith

EPA-HQ-OW-2008-0667-2374 David Bittner Delaware River Shad Fishermen's Association
Introduction 

FDMS Document ID First Name Middle 

Name Last Name Organization

EPA-HQ-OW-2008-0667-2375 R. Bloomgarden

EPA-HQ-OW-2008-0667-2376 M. Herman

EPA-HQ-OW-2008-0667-2377 E. and C. Fuller

EPA-HQ-OW-2008-0667-2378 S. F. Giuffrida

EPA-HQ-OW-2008-0667-2379 R. R. Holt

EPA-HQ-OW-2008-0667-2380 C. Schosser

EPA-HQ-OW-2008-0667-2381 G. Orbelian

EPA-HQ-OW-2008-0667-2382 C. Lester

EPA-HQ-OW-2008-0667-2383 M. and I. Spiegelman

EPA-HQ-OW-2008-0667-2384 S. Day

EPA-HQ-OW-2008-0667-2385 J. Rosenthal

EPA-HQ-OW-2008-0667-2386 Dr. J. Aronfreed

EPA-HQ-OW-2008-0667-2387 G. Gorman

EPA-HQ-OW-2008-0667-2388 L. Ruberg

EPA-HQ-OW-2008-0667-2389 P. Prouty

EPA-HQ-OW-2008-0667-2390 J. Ashbaugh

EPA-HQ-OW-2008-0667-2391 Reed W. Super Riverkeeper, Inc., et al. (Super Law Group, LLC)

EPA-HQ-OW-2008-0667-2392 Gov. John R. Kasich State of Ohio

EPA-HQ-OW-2008-0667-2393 Rebecca Troutman Riverkeeper, Inc., et al.

EPA-HQ-OW-2008-0667-2394 H. Morriss Barney IV Texas Municipal Power Agency (TMPA)

EPA-HQ-OW-2008-0667-2395 D. and A. Arnason

EPA-HQ-OW-2008-0667-2396 W. Herke

EPA-HQ-OW-2008-0667-2397 C. Dontopoulos

EPA-HQ-OW-2008-0667-2398 M. Randall

EPA-HQ-OW-2008-0667-2399 V. Mosca-Clark

EPA-HQ-OW-2008-0667-2400 M. Wahl

EPA-HQ-OW-2008-0667-2401 B. Winholtz

EPA-HQ-OW-2008-0667-2402 N. J. Mac

EPA-HQ-OW-2008-0667-2403 D. Givers

EPA-HQ-OW-2008-0667-2404 A. Garlan

EPA-HQ-OW-2008-0667-2405 G. Crouse

EPA-HQ-OW-2008-0667-2406 C. Heilman

EPA-HQ-OW-2008-0667-2407 C. Burns

EPA-HQ-OW-2008-0667-2408 J. McPeek

EPA-HQ-OW-2008-0667-2409 L. Green

EPA-HQ-OW-2008-0667-2410 G. and D. Peters and D. Peters

EPA-HQ-OW-2008-0667-2411 C. Compton

EPA-HQ-OW-2008-0667-2412 J. Cunningham

EPA-HQ-OW-2008-0667-2413 D. Emard
Introduction 

FDMS Document ID First Name Middle 

Name Last Name Organization

EPA-HQ-OW-2008-0667-2414 S. Baker

EPA-HQ-OW-2008-0667-2415 E. Ogella

EPA-HQ-OW-2008-0667-2416 J. Fletcher

EPA-HQ-OW-2008-0667-2417 K. A. Reynolds

EPA-HQ-OW-2008-0667-2418 C. Dzubak

EPA-HQ-OW-2008-0667-2419 M. Rudinow

EPA-HQ-OW-2008-0667-2420 L. Williams

EPA-HQ-OW-2008-0667-2421 R. Smith

EPA-HQ-OW-2008-0667-2422 R. Schutt

EPA-HQ-OW-2008-0667-2423 Anonymous

EPA-HQ-OW-2008-0667-2424 J. Bradfield

EPA-HQ-OW-2008-0667-2425 M. Swanson

EPA-HQ-OW-2008-0667-2426 S. McAdam

EPA-HQ-OW-2008-0667-2427 R. Moody

EPA-HQ-OW-2008-0667-2428 A. Bauer

EPA-HQ-OW-2008-0667-2429 W. Eddleman

EPA-HQ-OW-2008-0667-2430 M. O'Rourke

EPA-HQ-OW-2008-0667-2431 E. Kaliss

EPA-HQ-OW-2008-0667-2432 Jim Littlefield Surfers' Environmental Alliance (SEA)

EPA-HQ-OW-2008-0667-2433 S. Hathaway

EPA-HQ-OW-2008-0667-2434 G. Payne

EPA-HQ-OW-2008-0667-2435 S. Sapier

EPA-HQ-OW-2008-0667-2436 S. Sapier

EPA-HQ-OW-2008-0667-2437 Jack McCurdy and David Nelson Coastal Alliance on Plant Expansion

EPA-HQ-OW-2008-0667-2438 D. Ylvisaker

EPA-HQ-OW-2008-0667-2439 G. Lee

EPA-HQ-OW-2008-0667-2440 J. Adler

EPA-HQ-OW-2008-0667-2441 C. Head-Dylla

EPA-HQ-OW-2008-0667-2442 J. Wells

EPA-HQ-OW-2008-0667-2443 A. Long

EPA-HQ-OW-2008-0667-2444 J. Clemons

EPA-HQ-OW-2008-0667-2445 M. Ford

EPA-HQ-OW-2008-0667-2446 J. Meierotto

EPA-HQ-OW-2008-0667-2447 M. Wood

EPA-HQ-OW-2008-0667-2448 J. Quarles

EPA-HQ-OW-2008-0667-2449 J. Klein

EPA-HQ-OW-2008-0667-2450 A. Hengst

EPA-HQ-OW-2008-0667-2451 M. J. Cittadino

EPA-HQ-OW-2008-0667-2452 K. Floyd
Introduction 

FDMS Document ID First Name Middle 

Name Last Name Organization

EPA-HQ-OW-2008-0667-2453 B. Coulson

EPA-HQ-OW-2008-0667-2454 L. M. Conklin

EPA-HQ-OW-2008-0667-2455 Dr. F. Taylor

EPA-HQ-OW-2008-0667-2456 Christina T. Wisdom Texas Chemical Council (TCC)

EPA-HQ-OW-2008-0667-2457 Jonathan Oliver Arkansas Electric Cooperative Corporation (AECC)

EPA-HQ-OW-2008-0667-2458 Al DePaoli AES North America, L.P. (AES)

EPA-HQ-OW-2008-0667-2459 Michael A. Livermore, et al. Institute for Policy Integrity, New York University School 

of Law

EPA-HQ-OW-2008-0667-2460 P. Micklin

EPA-HQ-OW-2008-0667-2461 C. Koons

EPA-HQ-OW-2008-0667-2462 C. Miller

EPA-HQ-OW-2008-0667-2463 K. Aston

EPA-HQ-OW-2008-0667-2464 D. Halzack

EPA-HQ-OW-2008-0667-2465 F. Duschl

EPA-HQ-OW-2008-0667-2466 F. Boles

EPA-HQ-OW-2008-0667-2467 J. Holmes

EPA-HQ-OW-2008-0667-2468 M. Molina

EPA-HQ-OW-2008-0667-2469 T. Higgins

EPA-HQ-OW-2008-0667-2470 D. Lacey

EPA-HQ-OW-2008-0667-2471 L. Schlegel

EPA-HQ-OW-2008-0667-2472 G. Schmitz

EPA-HQ-OW-2008-0667-2473 G. Farm

EPA-HQ-OW-2008-0667-2474 B. Glassman

EPA-HQ-OW-2008-0667-2475 H. Gartsman

EPA-HQ-OW-2008-0667-2476 B. Crow

EPA-HQ-OW-2008-0667-2477 J. Ward

EPA-HQ-OW-2008-0667-2478 P. Totton

EPA-HQ-OW-2008-0667-2479 Robert H. Reider DTE Energy

EPA-HQ-OW-2008-0667-2480 Michalene Reilly Hoosier Energy REC, Inc.

EPA-HQ-OW-2008-0667-2481 Sara Barczak and Josh Galperin High Risk Energy Choices/Southern Alliance for Clean 

Energy

EPA-HQ-OW-2008-0667-2482 A. Ostrer

EPA-HQ-OW-2008-0667-2483 D. Bordenkircher

EPA-HQ-OW-2008-0667-2484 B. Ulbrich

EPA-HQ-OW-2008-0667-2485 M. Biernot

EPA-HQ-OW-2008-0667-2486 L. Wiener

EPA-HQ-OW-2008-0667-2487 L. Goin

EPA-HQ-OW-2008-0667-2488 M. Williams

EPA-HQ-OW-2008-0667-2489 L. Bagley
Introduction 

FDMS Document ID First Name Middle 

Name Last Name Organization

EPA-HQ-OW-2008-0667-2490 G. Schubert

EPA-HQ-OW-2008-0667-2491 C. Woodcock

EPA-HQ-OW-2008-0667-2492 A. Unger

EPA-HQ-OW-2008-0667-2493 J. Ramos

EPA-HQ-OW-2008-0667-2494 J. Scott The Bayou Manchac Group

EPA-HQ-OW-2008-0667-2495 J. Gregory

EPA-HQ-OW-2008-0667-2496 P. Manor

EPA-HQ-OW-2008-0667-2497 C. Shepard Connecticut Resource Recovery Authority

EPA-HQ-OW-2008-0667-2498 M. Stiefermann Central Electric Power Cooperative (CEEP)

EPA-HQ-OW-2008-0667-2499 J. Dillard

EPA-HQ-OW-2008-0667-2500 Sen. James M. Inhofe United States Senate

EPA-HQ-OW-2008-0667-2501 S. Shields

EPA-HQ-OW-2008-0667-2502 R. Rolfe

EPA-HQ-OW-2008-0667-2503 J. Dunn

EPA-HQ-OW-2008-0667-2504 L. Lambeth

EPA-HQ-OW-2008-0667-2505 S. Nichols

EPA-HQ-OW-2008-0667-2506 C. Zook

EPA-HQ-OW-2008-0667-2507 K. Robinson

EPA-HQ-OW-2008-0667-2508 B. Duncan

EPA-HQ-OW-2008-0667-2509 Mass Comment 

Campaign

Consumer Energy Alliance

EPA-HQ-OW-2008-0667-2510 J. Bindel Associated Electric Cooperative Inc. (AECI)

EPA-HQ-OW-2008-0667-2511 S. De Vos

EPA-HQ-OW-2008-0667-2512 K. Russell

EPA-HQ-OW-2008-0667-2513 M. Hnatowich

EPA-HQ-OW-2008-0667-2514 G.P. Kollarson

EPA-HQ-OW-2008-0667-2515 D. R. Nelson

EPA-HQ-OW-2008-0667-2516 K. Gibson

EPA-HQ-OW-2008-0667-2517 Anonymous

EPA-HQ-OW-2008-0667-2518 E. Dieterle

EPA-HQ-OW-2008-0667-2519 J. Pisano

EPA-HQ-OW-2008-0667-2520 J. Corliss

EPA-HQ-OW-2008-0667-2521 W. Wilgus

EPA-HQ-OW-2008-0667-2522 J. Phillips

EPA-HQ-OW-2008-0667-2523 M. Stone

EPA-HQ-OW-2008-0667-2524 M. Karp

EPA-HQ-OW-2008-0667-2525 A. Cockrell

EPA-HQ-OW-2008-0667-2526 D. Worden

EPA-HQ-OW-2008-0667-2527 S. Pyle
Introduction 

FDMS Document ID First Name Middle 

Name Last Name Organization

EPA-HQ-OW-2008-0667-2528 E. Craig

EPA-HQ-OW-2008-0667-2529 M. Hoffman

EPA-HQ-OW-2008-0667-2530 N. Bartol

EPA-HQ-OW-2008-0667-2531 S. Vilen

EPA-HQ-OW-2008-0667-2532 S. Young

EPA-HQ-OW-2008-0667-2533 D. Artley

EPA-HQ-OW-2008-0667-2534 K. Lieber

EPA-HQ-OW-2008-0667-2535 J. Emerson-Cobb

EPA-HQ-OW-2008-0667-2536 J. van Luik

EPA-HQ-OW-2008-0667-2537 S. Young

EPA-HQ-OW-2008-0667-2538 A. Nowicki

EPA-HQ-OW-2008-0667-2539 Eric J. Brown Connecticut Business & Industry Association (CBIA)

EPA-HQ-OW-2008-0667-2540 David Holt Consumer Energy Alliance (CEA)

EPA-HQ-OW-2008-0667-2541 Charles Furst Delaware River Shad Fisherman's Association (DRSFA)

EPA-HQ-OW-2008-0667-2542 Richard G. Burud Federated Rural Electric Association

EPA-HQ-OW-2008-0667-2543 Douglas Fingerson Goodhue County Cooperative Electric (GCCE)

EPA-HQ-OW-2008-0667-2544 Kris Ingenthron McLeod Cooperative Power Association

EPA-HQ-OW-2008-0667-2545 L. David Glatt North Dakota Department of Health (ND DOH)

EPA-HQ-OW-2008-0667-2546 S. Foku

EPA-HQ-OW-2008-0667-2547 Kavan L. Stull The Empire District Electric Company

EPA-HQ-OW-2008-0667-2548 Jonathan Scott The Bayou Manchac Group

EPA-HQ-OW-2008-0667-2549 Amy Goldsmith New Jersey Environmental Federation

EPA-HQ-OW-2008-0667-2550 Michael M. Hertel Southern California Edison (SCE)

EPA-HQ-OW-2008-0667-2551 Doug Whitley Illinois Chamber of Commerce

EPA-HQ-OW-2008-0667-2552 Gov. Eddie Baza Calvo Island of Guam

EPA-HQ-OW-2008-0667-2553 Gov. John H. Lynch State of New Hampshire

EPA-HQ-OW-2008-0667-2554 K. Ferguson

EPA-HQ-OW-2008-0667-2555 E. Nickelson

EPA-HQ-OW-2008-0667-2556 S. Richards

EPA-HQ-OW-2008-0667-2557 M. Stinner

EPA-HQ-OW-2008-0667-2558 S. Mehrotra

EPA-HQ-OW-2008-0667-2559 J. Burgess

EPA-HQ-OW-2008-0667-2560 Mass Comment 

Campaign

Unknown

EPA-HQ-OW-2008-0667-2561 Mass Comment 

Campaign

Unknown

EPA-HQ-OW-2008-0667-2562 Mass Comment 

Campaign

Unknown

EPA-HQ-OW-2008-0667-2563 P. Angelo
Introduction 

FDMS Document ID First Name Middle 

Name Last Name Organization

EPA-HQ-OW-2008-0667-2564 J. Link

EPA-HQ-OW-2008-0667-2565 J. Benson

EPA-HQ-OW-2008-0667-2566 J. Steitz

EPA-HQ-OW-2008-0667-2567 T. Sherman

EPA-HQ-OW-2008-0667-2568 Reed W. Super Riverkeeper, Inc., et al. (Super Law Group, LLC)

EPA-HQ-OW-2008-0667-2569 Reed W. Super Riverkeeper, Inc., et al. (Super Law Group, LLC)

EPA-HQ-OW-2008-0667-2570 Reed W. Super Riverkeeper, Inc., et al. (Super Law Group, LLC)

EPA-HQ-OW-2008-0667-2571 Reed W. Super Riverkeeper, Inc., et al. (Super Law Group, LLC)

EPA-HQ-OW-2008-0667-2572 Reed W. Super Riverkeeper, Inc., et al. (Super Law Group, LLC)

EPA-HQ-OW-2008-0667-2573 Reed W. Super Riverkeeper, Inc., et al. (Super Law Group, LLC)

EPA-HQ-OW-2008-0667-2574 State Rep. Gregory M. Davids Minnesota State House of Representatives

EPA-HQ-OW-2008-0667-2575 J. Miner

EPA-HQ-OW-2008-0667-2576 B. Russell

EPA-HQ-OW-2008-0667-2577 T. Lowell

EPA-HQ-OW-2008-0667-2578 B. Bender

EPA-HQ-OW-2008-0667-2579 L. Smith

EPA-HQ-OW-2008-0667-2580 W. Hodges

EPA-HQ-OW-2008-0667-2581 John G. Valeri Jr., Wolff and Samson (PSEG Fossil LLC and PSEG Nuclear 

LLC)

EPA-HQ-OW-2008-0667-2582 John Rogers Union of Concerned Scientists (UCS)

EPA-HQ-OW-2008-0667-2584 H. Scanlon

EPA-HQ-OW-2008-0667-2585 J. Bulger

EPA-HQ-OW-2008-0667-2907 John W. Myers Tennessee Valley Authority (TVA)

EPA-HQ-OW-2008-0667-2908 John W. Myers Tennessee Valley Authority (TVA)

EPA-HQ-OW-2008-0667-2909 John J. Novak National Rural Electric Cooperative Association (NRECA)

EPA-HQ-OW-2008-0667-2910 Erik Silvola Great River Energy (GRE)

EPA-HQ-OW-2008-0667-2911 David Anderson Passavant Geiger

EPA-HQ-OW-2008-0667-2912 Shirley M. Ruffin SCANA Corporation

EPA-HQ-OW-2008-0667-2913 Michael J. Smith Capital Power Corporation (Murtha Cullina LLP)

EPA-HQ-OW-2008-0667-2914 John T. Graves Minnkota Power Cooperative, Inc.

EPA-HQ-OW-2008-0667-2915 JoAnne Rau The Dayton Power & Light Company (DP&L)

EPA-HQ-OW-2008-0667-2916 Nick Schroeck Great Lakes Environmental Law Center (GLELC)

EPA-HQ-OW-2008-0667-2917 Mark Thoma Otter Tail Power Company

EPA-HQ-OW-2008-0667-2918 Dan Sutter The George Washington University Regulatory Studies 

Center

EPA-HQ-OW-2008-0667-2919 Winston K. Borkowski Florida Electric Power Coordinating Group, Inc. (FCG) 

(Hopping Green and Sams)

EPA-HQ-OW-2008-0667-2920 Kathleen Moser New York State Department of Environmental 

Conservation (NYSDEC)
Introduction 

FDMS Document ID First Name Middle 

Name Last Name Organization

EPA-HQ-OW-2008-0667-2921 Maria Valdez The Dow Chemical Company

EPA-HQ-OW-2008-0667-2922 Robert Rapenske Eagle Point Power Generation, LLC (EPPG)

EPA-HQ-OW-2008-0667-2923 Douglas Mauro Rockland Capital Cape May Holdings, LLC (RCCMH)

EPA-HQ-OW-2008-0667-2924 Steven C. Whitworth Ameren Corporation

EPA-HQ-OW-2008-0667-2925 Ronald R. Cox Hawaiian Electric Company

EPA-HQ-OW-2008-0667-2926 J. Michael Brown Ohio Valley Electric Corporation (OVEC) and IndianaKentucky Electric Corporation (IKEC)

EPA-HQ-OW-2008-0667-2927 John M. MacDonald Public Service of New Hampshire (PSNH)

EPA-HQ-OW-2008-0667-2928 John J. Novak National Rural Electric Cooperative Association (NRECA)

EPA-HQ-OW-2008-0667-2929 Randall R. LaBauve NextEra Energy

EPA-HQ-OW-2008-0667-2930 Kathleen Moser New York State Department of Environmental 

Conservation (NYSDEC)

EPA-HQ-OW-2008-0667-2931 Melissa Lavinson Pacific Gas and Electric Company (PG&E)

EPA-HQ-OW-2008-0667-2936 Patrick O'Loughlin Buckeye Power, Inc.

EPA-HQ-OW-2008-0667-2937 Pam Faggert Dominion Resources Services, Inc.

EPA-HQ-OW-2008-0667-2938 Basil G. Constantelos Midwest Generation, Edison Mission Energy, LLC

EPA-HQ-OW-2008-0667-2939 Patrick Blachard Calpine Corporation

EPA-HQ-OW-2008-0667-2940 Alan R. Wood American Electric Power (AEP)

EPA-HQ-OW-2008-0667-2941 Hanneke Counts Eastman Chemical Company

EPA-HQ-OW-2008-0667-2942 William J. Donohue and Amy M. Trojecki Exelon Corporation

EPA-HQ-OW-2008-0667-2943 Russell Frye Cooling Water Intake Structure Coalition

EPA-HQ-OW-2008-0667-2944 Joe L. Citta, Jr. Nebraska Public Power District (NPPD)

EPA-HQ-OW-2008-0667-2945 Russell J. Furnari PSEG Power LLC

EPA-HQ-OW-2008-0667-2946 Cari Boyce Duke Energy Business Services, LLC

EPA-HQ-OW-2008-0667-2947 Basil G. Constantelos Midwest Generation, Edison Mission Energy, LLC

EPA-HQ-OW-2008-0667-2948 Roger E. Claff American Petroleum Institute (API)

EPA-HQ-OW-2008-0667-2949 Roger E. Claff American Petroleum Institute (API)

EPA-HQ-OW-2008-0667-2950 Kevin M. Brinegar Indiana Chamber of Commerce

EPA-HQ-OW-2008-0667-2951 Pamela F. Faggert Dominion Resources Services, Inc.

EPA-HQ-OW-2008-0667-2952 Michael Bradley Clean Energy Group

EPA-HQ-OW-2008-0667-2953 Chad Miller Montana-Dakota Utilities Co.

EPA-HQ-OW-2008-0667-2954 Patrick Flowers Xcel Energy, Inc.

EPA-HQ-OW-2008-0667-2955 Mike Godfrey Alabama Power Company (APC)

EPA-HQ-OW-2008-0667-2956 Louisa Eclarinal City Public Service of San Antonio (CPS Energy)

EPA-HQ-OW-2008-0667-2957 Ronald R. Cox Hawaiian Electric Company

EPA-HQ-OW-2008-0667-2958 J. Michael Brown Ohio Valley Electric Corporation (OVEC) and IndianaKentucky Electric Corporation (IKEC)

EPA-HQ-OW-2008-0667-2959 Michael L. Krancer Pennsylvania Department of Environmental Protection 

(DEP)
Introduction 

FDMS Document ID First Name Middle 

Name Last Name Organization

EPA-HQ-OW-2008-0667-2960 Patrick Flowers Xcel Energy, Inc.

EPA-HQ-OW-2008-0667-2961 Alexandra Dapolito Dunn Association of Clean Water Administrators (ACWA)

EPA-HQ-OW-2008-0667-2962 Douglas A. Dixon Electric Power Research Institute (EPRI)

EPA-HQ-OW-2008-0667-2963 Theresa Pugh American Public Power Association (APPA)

EPA-HQ-OW-2008-0667-2964 Curtis Q. Wagner Arkansas Electric Cooperative Corporation (AECC)

EPA-HQ-OW-2008-0667-2965 Maria Valdez The Dow Chemical Company

EPA-HQ-OW-2008-0667-2966 Randall R. LaBauve NextEra Energy

EPA-HQ-OW-2008-0667-2967 Kavan L. Stull The Empire District Electric Company

EPA-HQ-OW-2008-0667-2968 Edward R. Griegel Sunbury Generation LP (Manko, Gold, Katcher & Fox, LP)

EPA-HQ-OW-2008-0667-2969 Pilar Patterson New Jersey Department of Environmental Protection 

(NJDEP)

EPA-HQ-OW-2008-0667-2970 Brendan Mascarenhas American Chemistry Council (ACC)

EPA-HQ-OW-2008-0667-2971 Fred T. Harnack United States Steel Corporation (USS)

EPA-HQ-OW-2008-0667-2972 Cari Boyce Duke Energy Business Services, LLC

EPA-HQ-OW-2008-0667-2973 David M. Fraley City Utilities of Springfield, Missouri (CU)

EPA-HQ-OW-2008-0667-2974 Robert Matty and Angela M. Grooms Utility Water Act Group (UWAG) (Hunton & Williams LLP)

EPA-HQ-OW-2008-0667-2975 Jerry Purvis East Kentucky Power Cooperative (EKPC)

EPA-HQ-OW-2008-0667-2976 Thomas R. Kuhn Edison Electric Institute (EEI)

EPA-HQ-OW-2008-0667-2977 Hanneke Counts Eastman Chemical Company

EPA-HQ-OW-2008-0667-2978 Robert A. Reich DuPont Safety, Health and Environment (SHE) & 

Sustainable Growth Center

EPA-HQ-OW-2008-0667-2979 Mark J. Sedlacek Los Angeles Department of Water and Power (LADWP)

EPA-HQ-OW-2008-0667-2980 Claire M. Olson Basin Electric Power Cooperative

EPA-HQ-OW-2008-0667-2981 Bill Matthews Cleco Corporation

EPA-HQ-OW-2008-0667-2982 Gary A. Dawson Consumers Energy

EPA-HQ-OW-2008-0667-2983 Shawn Glacken Luminant

EPA-HQ-OW-2008-0667-2984 Melissa Lavinson Pacific Gas and Electric Company (PG&E)

EPA-HQ-OW-2008-0667-2985 Michael G. Cashin Minnesota Power (ALLETE)

EPA-HQ-OW-2008-0667-2986 Nicholas M. Demik Northern Indiana Public Service Company (NIPSCO)

EPA-HQ-OW-2008-0667-2987 Verne Shortell NRG Energy, Inc.

EPA-HQ-OW-2008-0667-2988 Kay L. Nelson Northwest Indiana Forum

EPA-HQ-OW-2008-0667-2989 Chris M. Hobson Southern Company

EPA-HQ-OW-2008-0667-2990 Cheri A. Budzynski Ohio Utility Group (OUG) (Shumaker, Loop & Kendrick, 

LLP)

EPA-HQ-OW-2008-0667-2991 Christina T. Wisdom Texas Chemical Council (TCC)

EPA-HQ-OW-2008-0667-2994 Mike Godfrey Alabama Power Company (APC)

EPA-HQ-OW-2008-0667-2995 Chris M. Hobson Southern Company

EPA-HQ-OW-2008-0667-2996 Henry Eby Lower Colorado River Authority (LCRA)

EPA-HQ-OW-2008-0667-2999 Jerry Bonanno and William Skaff Nuclear Energy Institute (NEI)
Introduction 

FDMS Document ID First Name Middle 

Name Last Name Organization

EPA-HQ-OW-2008-0667-3000 Chris M. Hobson Southern Company

EPA-HQ-OW-2008-0667-3001 Patrick Blachard Calpine Corporation

EPA-HQ-OW-2008-0667-3002 Michael Bradley Clean Energy Group

EPA-HQ-OW-2008-0667-3004 Jerry Bonanno and William Skaff Nuclear Energy Institute (NEI)

EPA-HQ-OW-2008-0667-3005 Christina T. Widsom Texas Chemical Council (TCC)

EPA-HQ-OW-2008-0667-3006 Elise N. Zoli Entergy Corporation (Goodwin Procter LLP)

EPA-HQ-OW-2008-0667-3007 H. Morriss Barney, IV Texas Municipal Power Agency (TMPA)

EPA-HQ-OW-2008-0667-3008 Brendan Mascarenhas American Chemistry Council (ACC)

EPA-HQ-OW-2008-0667-3009 Joseph Dominguez Exelon Corporation

EPA-HQ-OW-2008-0667-3010 Reed W. Super Riverkeeper, Inc. et al. (Super Law Group, LLC)

EPA-HQ-OW-2008-0667-3011 Russell Frye Cooling Water Intake Structure Coalition

EPA-HQ-OW-2008-0667-3012 Thomas R. Kuhn and Christopher M. Crane Edison Electric Institute (EEI) and Exelon Corporation

EPA-HQ-OW-2008-0667-3013 R. Matty, A. M. 

Grooms,

and C. R. Bozek Utility Water Act Group (UWAG) and Edison Electric 

Institute (EEI) (Hunton and Williams LLP)

EPA-HQ-OW-2008-0667-3014 Robert H. Reider DTE Energy

EPA-HQ-OW-2008-0667-3015 Jeannine M. Hammer FirstEnergy Corp. (FE)

EPA-HQ-OW-2008-0667-3016 Nysa Hogue Indianapolis Power & Light Company (IPL)

EPA-HQ-OW-2008-0667-3017 Mark J. Sedlacek Los Angeles Department of Water and Power (LADWP)

EPA-HQ-OW-2008-0667-3018 Sam L. Phillips Louisiana Department of Environmental Quality (LDEQ)

EPA-HQ-OW-2008-0667-3019 William Creal Michigan Department of Environmental Quality (MDEQ)

EPA-HQ-OW-2008-0667-3020 Reed W. Super Riverkeeper, Inc. et al. (Super Law Group, LLC)

EPA-HQ-OW-2008-0667-3021 Reed W. Super Riverkeeper, Inc. et al. (Super Law Group, LLC)

EPA-HQ-OW-2008-0667-3022 Brendan Mascarenhas American Chemistry Council (ACC)

EPA-HQ-OW-2008-0667-3023 Chris M. Hobson Southern Company

EPA-HQ-OW-2008-0667-3024 Shawn Glacken Luminant

EPA-HQ-OW-2008-0667-3025 G. Adams

EPA-HQ-OW-2008-0667-3026 J. Bagatta

EPA-HQ-OW-2008-0667-3027 J. Valentine

EPA-HQ-OW-2008-0667-3028 I. Rabois

EPA-HQ-OW-2008-0667-3029 P. Brocious

EPA-HQ-OW-2008-0667-3030 M. Owen

EPA-HQ-OW-2008-0667-3031 W. Fast

EPA-HQ-OW-2008-0667-3032 K. Hughes

EPA-HQ-OW-2008-0667-3033 J. W. Soffler

EPA-HQ-OW-2008-0667-3034 L. A. Gianella

EPA-HQ-OW-2008-0667-3035 T. and D. Merritts

EPA-HQ-OW-2008-0667-3036 L. Perret

EPA-HQ-OW-2008-0667-3037 E. H. Oblas

EPA-HQ-OW-2008-0667-3038 Anonymous
Introduction 

FDMS Document ID First Name Middle 

Name Last Name Organization

EPA-HQ-OW-2008-0667-3039 Peggy Cullen

EPA-HQ-OW-2008-0667-3040 Anonymous

EPA-HQ-OW-2008-0667-3041 B. Vaughn

EPA-HQ-OW-2008-0667-3042 M. Williams

EPA-HQ-OW-2008-0667-3043 E. Butler

EPA-HQ-OW-2008-0667-3044 K. Garton

EPA-HQ-OW-2008-0667-3045 K. A. Barry

EPA-HQ-OW-2008-0667-3046 C. E. Arkema

EPA-HQ-OW-2008-0667-3047 J. Tavares

EPA-HQ-OW-2008-0667-3048 K. Spath

EPA-HQ-OW-2008-0667-3049 N. Gibbs

EPA-HQ-OW-2008-0667-3050 T. Linter

EPA-HQ-OW-2008-0667-3051 Anonymous

EPA-HQ-OW-2008-0667-3052 D. Caraballo

EPA-HQ-OW-2008-0667-3053 C. Skibell

EPA-HQ-OW-2008-0667-3054 J. McDermott

EPA-HQ-OW-2008-0667-3055 A. Oppenheim

EPA-HQ-OW-2008-0667-3056 V. Keramaty

EPA-HQ-OW-2008-0667-3057 J. Rigney

EPA-HQ-OW-2008-0667-3058 J. Ashton

EPA-HQ-OW-2008-0667-3059 D. Weinstein

EPA-HQ-OW-2008-0667-3060 L. Flanagan

EPA-HQ-OW-2008-0667-3061 A. Brana

EPA-HQ-OW-2008-0667-3062 Anonymous

EPA-HQ-OW-2008-0667-3063 M. Malina

EPA-HQ-OW-2008-0667-3064 Mass Comment 

Campaign

Riverkeeper

EPA-HQ-OW-2008-0667-3065 J. E. Fletcher

EPA-HQ-OW-2008-0667-3066 Anonymous

EPA-HQ-OW-2008-0667-3067 W. D. Rizer

EPA-HQ-OW-2008-0667-3068 Anonymous

EPA-HQ-OW-2008-0667-3069 D. Dutelle

EPA-HQ-OW-2008-0667-3070 R. Capozzi

EPA-HQ-OW-2008-0667-3071 C. Curtin

EPA-HQ-OW-2008-0667-3072 Anonymous

EPA-HQ-OW-2008-0667-3073 S. Didrichsen

EPA-HQ-OW-2008-0667-3074 C. Schmidt

EPA-HQ-OW-2008-0667-3075 D. Tignanelli

EPA-HQ-OW-2008-0667-3076 A. Zito
Introduction 

FDMS Document ID First Name Middle 

Name Last Name Organization

EPA-HQ-OW-2008-0667-3077 M. Lynn

EPA-HQ-OW-2008-0667-3078 S. Eisenstark

EPA-HQ-OW-2008-0667-3079 D. Douglas

EPA-HQ-OW-2008-0667-3080 Patricia D. Horn and Kenneth E. Raymond Oklahoma Gas and Electric Company (OG&E)

EPA-HQ-OW-2008-0667-3081 P. Packer

EPA-HQ-OW-2008-0667-3082 B. Buttacavoli

EPA-HQ-OW-2008-0667-3083 M. and S. Patterson

EPA-HQ-OW-2008-0667-3084 Anonymous

EPA-HQ-OW-2008-0667-3085 Anonymous

EPA-HQ-OW-2008-0667-3086 M. N. Perskin

EPA-HQ-OW-2008-0667-3087 M. Sims

EPA-HQ-OW-2008-0667-3088 E. Pasquale

EPA-HQ-OW-2008-0667-3089 B. Kanninen

EPA-HQ-OW-2008-0667-3090 Mass Comment 

Campaign

Sierra Club

EPA-HQ-OW-2008-0667-3091 A. Violi

EPA-HQ-OW-2008-0667-3092 K. Gluth

EPA-HQ-OW-2008-0667-3093 Daisy Hoyt

EPA-HQ-OW-2008-0667-3094 L. Neiman

EPA-HQ-OW-2008-0667-3095 V. Gilbert

EPA-HQ-OW-2008-0667-3096 F. Stearney

EPA-HQ-OW-2008-0667-3097 Anonymous

EPA-HQ-OW-2008-0667-3098 K. Sherwood

EPA-HQ-OW-2008-0667-3099 S. Rose

EPA-HQ-OW-2008-0667-3100 S. W. Sabath

EPA-HQ-OW-2008-0667-3101 G. Morotti

EPA-HQ-OW-2008-0667-3102 Mass Comment 

Campaign

Unknown

EPA-HQ-OW-2008-0667-3103 R. L. Adzema

EPA-HQ-OW-2008-0667-3104 N. Mantas

EPA-HQ-OW-2008-0667-3105 A. Montapert

EPA-HQ-OW-2008-0667-3106 W. G. Murtha

EPA-HQ-OW-2008-0667-3107 A. Smock

EPA-HQ-OW-2008-0667-3108 J. M. Naples

EPA-HQ-OW-2008-0667-3109 L. B. Miller

EPA-HQ-OW-2008-0667-3110 M. Sonderskov

EPA-HQ-OW-2008-0667-3111 T. E. Webb

EPA-HQ-OW-2008-0667-3112 R. Feldman

EPA-HQ-OW-2008-0667-3113 M. Half
Introduction 

FDMS Document ID First Name Middle 

Name Last Name Organization

EPA-HQ-OW-2008-0667-3114 R. B. Hare

EPA-HQ-OW-2008-0667-3115 K. Maher

EPA-HQ-OW-2008-0667-3116 J. Rosenthal

EPA-HQ-OW-2008-0667-3117 F. and J. Fusco

EPA-HQ-OW-2008-0667-3118 J. Papandrea

EPA-HQ-OW-2008-0667-3119 Anonymous

EPA-HQ-OW-2008-0667-3120 S. Rose

EPA-HQ-OW-2008-0667-3121 Anonymous

EPA-HQ-OW-2008-0667-3122 Anonymous

EPA-HQ-OW-2008-0667-3123 L. D'Arco

EPA-HQ-OW-2008-0667-3124 N. Weber

EPA-HQ-OW-2008-0667-3125 C. Delfeld

EPA-HQ-OW-2008-0667-3126 Anonymous

EPA-HQ-OW-2008-0667-3127 J. R. Pitcher, Jr.

EPA-HQ-OW-2008-0667-3128 T. Brown

EPA-HQ-OW-2008-0667-3129 S. Sobanski

EPA-HQ-OW-2008-0667-3130 J. Ramos

EPA-HQ-OW-2008-0667-3131 P. Wolf

EPA-HQ-OW-2008-0667-3132 M. Ricapito

EPA-HQ-OW-2008-0667-3133 N. Castaldo

EPA-HQ-OW-2008-0667-3134 A. Havan

EPA-HQ-OW-2008-0667-3135 D. Moderacki

EPA-HQ-OW-2008-0667-3136 N. Neumann

EPA-HQ-OW-2008-0667-3137 Patrick R. Varekamp

EPA-HQ-OW-2008-0667-3138 B. L. Close

EPA-HQ-OW-2008-0667-3139 A. Vrankovic

EPA-HQ-OW-2008-0667-3140 Dr. J. Olejak

EPA-HQ-OW-2008-0667-3141 Anonymous

EPA-HQ-OW-2008-0667-3142 R. Lebensold

EPA-HQ-OW-2008-0667-3143 S. Etherton

EPA-HQ-OW-2008-0667-3144 C. Accorsi

EPA-HQ-OW-2008-0667-3145 N. Valenti

EPA-HQ-OW-2008-0667-3146 Tom J. Mulford Electric Power Research Institute (EPRI)

EPA-HQ-OW-2008-0667-3147 Anonymous Alcoa - Warrick Operations

EPA-HQ-OW-2008-0667-3148 Richard Schneider Coalition to Protect Fisheries

EPA-HQ-OW-2008-0667-3149 Tom J. Mulford Electric Power Research Institute (EPRI)
Response to Comment Essays 
Essay	 	 	 	 	 	 	 	 	 	 1: General Support of the 316(b) Existing Facilities Rule

EPA acknowledges your support for promulgating a strong rule under section 316(b) of the 

Clean Water Act (CWA) that establishes national requirements for existing power generating 

facilities and existing manufacturing and industrial facilities that withdraw water from waters of 

the U.S. for cooling purposes. These national requirements apply to the location, design, 

construction, and capacity of cooling water intake structures (CWIS) at regulated facilities by 

setting requirements that reflect the best technology available (BTA) for minimizing adverse 

environmental impact on aquatic organisms and ecosystems. 

This essay addresses comments from the public expressing support for the proposed rule and 

possible revisions to the final rule that were discussed in the NODAs. In the proposed rule and 

the notices of data availability (NODAs), EPA considered a variety of options for establishing 

requirements for existing power generating and manufacturing and industrial facilities that 

withdraw water from waters of the U.S. exclusively for cooling purposes. In many cases, 

commenters advocated that EPA take a strong stance for protecting the environment in strictly 

regulating facilities withdrawing cooling water, with particular attention to regulating nuclear 

facilities (generally, these commenters were private citizens or environmental groups). Many 

commenters expressed particular support of the possible rule revisions discussed in the NODAs, 

noting the flexibility and site-specific approaches provided in the possible revisions (generally, 

these commenters were representatives of state and local governments (i.e. municipally owned 

utilities) or industry groups). Some commenters expressed support for portions of the rule, but 

suggested specific modifications to other parts of the rule (these commenters were also 

representatives of utilities or industry groups). These commenters proceeded to detail their 

specific modification suggestions in later comments that are addressed in other essays 

responding to comments. 

With today’s rule, EPA is promulgating a rule that completes the Agency’s regulations under 

section 316(b) of the CWA. Please see the preamble for the final rule for EPA’s rationale in 

developing the final rule requirements. 

Essay 1 1 
Essay	 	 	 2: General Opposition	 	 	 	 	 	 	 of the 316(b) Existing Facilities Rule

This essay addresses comments from the public expressing opposition to the proposed rule and 

possible revisions to the final rule that were discussed in the NODAs. In the proposed rule and 

the notices of data availability (NODAs), EPA considered a variety of options for establishing 

requirements under section 316(b) of the Clean Water Act (CWA) for existing power generating 

and manufacturing and industrial facilities that withdraw water from waters of the U.S. 

exclusively for cooling purposes. In general, commenters expressed concern about the provisions 

of the proposed rule, with many commenters emphasizing the economic burden on affected 

facilities and poor cost-benefit return in implementing the rule as written (these commenters 

were mostly representatives of utilities, industry groups, and government agencies). A small 

number of commenters opposed the rule because they felt it is not sufficiently stringent and 

allows affected facilities to continue to cause unacceptable adverse impacts on the environment 

(these comments were all from environmental groups). Several commenters opposed EPA 

regulation in general (these comments were all from private citizens). Some commenters 

suggested specific modifications to parts of the rule. These commenters proceeded to detail their 

specific modification suggestions in later comments that are addressed in other essays. 

Today, EPA promulgates a final rule that completes the Agency’s regulations under section 

316(b) of the CWA. Please see the preamble for the final rule for EPA’s rationale in developing 

the final rule requirements. 

Essay 2 2 
Essay	 	 4: Background Information	 	 about Commenter

EPA appreciates all comments on its rulemaking process. The Agency received comments from 

a diverse group of stakeholders, including concerned industry, environmental group, private 

citizen, and academic representatives, as well as comments from all levels of local, state, and 

federal government. Today’s final rulemaking will apply to the majority of the existing U.S. 

power generation fleet as well as certain manufacturing facilities. Based on its calculations, EPA 

has determined that the final rule will have relatively minor economic impacts on the regulated 

facilities, the entities that own them, and the overall electric power sector, which encompasses a 

large portion of the facilities that may be subject to today’s rule. See the preamble for the final 

rule and the EA for EPA’s analysis of costs and economic impacts (including electricity supply). 

This essay addresses public comments providing background information about the commenters. 

Within the background information presented, some commenters expressed concerns about the 

proposed rule or the notices of data availability (NODAs). In general, these comments expressed 

that the rule should be (or concern that it is not) cost-effective, feasible, and/or use a site-specific 

approach to meet environmental objectives, or made broad suggestions about how the rule could 

be so. These types of comment were only submitted by industry commenters. A few commenters 

expressed support for the rule or the need for a strong rule. These comments were submitted by 

environmental organizations and private citizens. The vast majority of the comments simply 

presented background information about the commenter, expressed the commenter’s 

appreciation for the opportunity to comment, stated that the rule will affect commenter, and/or 

comprised in-text editorial or summary remarks that did not contain substantive content. All 

types of commenters submitted these kinds of remarks. 

In developing today’s final rule, EPA collected and analyzed a substantial amount of information 

regarding cooling water intake structures, their biological impacts, available technologies to 

reduce those impacts, the potential impacts and costs of utilizing those technologies, and other 

relevant subjects, including information submitted by stakeholders, industry groups, technology 

vendors, and environmental organizations. The Agency has met with representatives from 

facilities and affected industries on topics including the latest advancements in fish protection 

technologies, permitting experience, and the feasibility and cost of installing technologies at 

various types of facilities. EPA conducted site visits at over 50 power plants and manufacturing 

sites to: gather information on the intake technologies and cooling water systems in place at a 

wide variety of existing facilities; gather performance data for technologies and affected 

biological resources; and listen to perspectives from industry representatives. EPA has continued 

to exchange information with various stakeholders in the development of today’s final rule. 

The Agency has reviewed and analyzed data from all types of facilities and situations that will be 

affected by the rule and developed compliance options that provide sufficient flexibility to the 

regulated community. EPA considered a variety of considerations (such as possible differences 

between generators and manufacturers, between manufacturing facilities in different sectors, 

among facilities in diverse geographical locations, and between facilities that do or do not 

withdraw very large volumes of cooling water) but ultimately rejected most subcategories as 

inappropriate. See Essays 14, 19 and the Technical Development Document (TDD) for more 

Essay 4 3 
information. EPA has also reviewed data and comment submitted in response to the proposed 

rule and NODAs and incorporated the information into the development of BTA requirements 

and compliance alternatives. Today’s final rule is both reasonable and scientifically sound. 

Today’s final rule reflects the best technology available for minimizing adverse environmental 

impacts associated with cooling water intake structures and allows the regulated universe the 

flexibility to meet critical environmental objectives through reasonable and cost effective 

compliance options. The flexibility and compliance schedule in the rule allows facilities to 

undertake necessary upgrades without affecting reliability of energy delivery. Today’s final rule 

will improve the quality of our nation’s waters by minimizing adverse environmental impacts 

associated with cooling water intake structures by substantially reducing the mortality of aquatic 

organisms due to impingement and entrainment, provide a national framework for compliance, at 

an affordable cost to affected facilities and ratepayers. 

Please refer to Essay 19 for a discussion of regulatory options. 

Essay 4 4 
	 	 	 	 	 	 	 	 	 	 	

	 	 	 	 	 	 	 	 	

	 	 	 	 	 	 	 	 	

	 	 	 	 	 	 	 	 	

	 	 	 	

Essay 5: Form Letters 1‐14, Addressing Form Letters from the Alliance

for the Great Lakes, Consumer Energy Alliance, Natural Resources

Defense Council, Environmental Law and Policy Center, Sierra Club,

National Wildlife Federation Action Fund, Food and Water Watch,

Surfrider, Riverkeeper, and Other Unknown Organizations

This essay addresses private citizens that participated in form letter campaigns for various 

organizations. The majority of these comments were from environmental organizations in 

support of a strong national rule requiring closed-cycle recirculating systems (CCRS) as besttechnology available. Commenters indicated that closed-cycle cooling is readily available. EPA 

also received form letters from the Consumer Energy Alliance, which supported site-specific 

standards, cost-benefit analyses for determining appropriate implementation measures, and 

maximizing implementation flexibility of the rule. Form letters submitted on behalf of the 

Consumer Energy Alliance stated that 316(b) regulations would cause “catastrophic” effects for 

consumers. Some commenters included additional comments with their form letters. Many of 

these additional comments were background, nonsubstantive, specific to individual facilities, or 

not relevant to the 316(b) regulation and require no further response from EPA than provided 

here. Some commenters were concerned about nuclear or fossil-fuel-powered generating 

facilities and/or thermal pollution from generators’ discharges. 

EPA agrees with the need for promulgating a strong rule under section 316(b) of the Clean Water 

Act (CWA) that establishes national requirements for existing power generating facilities and 

existing manufacturing and industrial facilities that withdraw water from waters of the U.S. for 

cooling purposes. 

EPA has promulgated final regulations that will provide consistency and aid in minimizing 

adverse environmental impacts associated with cooling water intake structures by substantially 

reducing the mortality of aquatic organisms due to impingement and entrainment. EPA estimates 

that the final rule will achieve significant monetized benefits to society through protection of 

commercially and recreationally harvested fish while incurring relatively minor economic impact 

on regulated facilities, the entities that own them, and the overall electric power sector and 

electricity consumers. 

EPA agrees that flexibility is important, and EPA has promulgated a final rule that addresses 

commenter concerns about implementation flexibility and site-specific approaches, provides the 

desired flexibility for both the permittee and the Director to determine the most appropriate and 

cost-effective means for meeting the requirements of today’s rule while maintaining performance 

standards that will minimize adverse environmental impacts. 

For the reasons explained in the preamble and Essay 15, EPA does not agree with commenters 

that stated that closed-cycle is readily available. 

This rule, which implements section 316(b) of the Clean Water Act, will provide effective and 

efficient progress towards restoring, maintaining and protecting, the physical, chemical and 

Essay 5 5 
biological integrity of our nation’s waters. It establishes national BTA standards for 

impingement mortality and entrainment: impingement mortality standards at all existing facilities 

that withdraw over 2 mgd DIF that include seven compliance alternatives; an entrainment 

standard based on site-specific entrainment controls determined by the EPA or the State NPDES 

permitting authority for existing facilities (other than new units) that withdraw over 2 mgd DIF. 

See the preamble and Essay 19. 

EPA does not agree with the comment that today’s final rule would cause “catastrophic” effects 

for consumers. As stated in the preamble, and as explained in economic support documents in 

the record for the rule, the final regulation will result in only modest impacts to consumers. For 

responses to the form letter from Consumer Energy Alliance, also see Essay 15. 

Issues regarding the use of nuclear or fossil fuels in generating power and other concerns not 

relevant to the section 316(b) regulation are beyond the scope of this rulemaking. Issues 

regarding concerns about thermal pollution from electricity generation facilities are outside the 

scope of this rulemaking as they are addressed in regulations related to section 316(a) of the 

Clean Water Act. 

Essay 5 6 
Essay 6: Comment Period, Schedule for Final Rule

This essay addresses public comments on the comment period for the proposal and the schedule 

for the final rule related to the notices of data availability (NODAs) for today’s final rule. EPA 

received requests from 9 commenters for EPA to ask the federal district court to extend the 

deadline for completing the rulemaking. These commenters expressed concern that the time 

allotted would be insufficient for EPA to adequately review and respond to the comments 

submitted on the NODAs. EPA received requests from two commenters for 60-day comment 

period extensions for the proposal comment period. Additionally, two commenters thought the 

public had been denied the opportunity to comment on actual monetized benefits of proposed 

rule, because the analysis of benefits was not complete at proposal. Also, one commenter asked 

if there would be opportunity to comment on revised IM standards prior to finalization of rule. 

Finally, one commenter expressed concern about the transparency of the rulemaking process, 

stating that EPA did not comply with the Office of Management and Budget’s Executive Order 

13563 for the NODAs. 

EPA Provided an Adequate Opportunity to Comment

EPA provided an adequate opportunity to comment on the proposed rule. EPA provided an 

opportunity to comment on the proposal and as a result, decided to issue for public comment a 

notice of data availability seeking additional comment on certain issues raised in the initial 

comment period, particularly with respect to impingement mortality. In addition, this rulemaking 

has been ongoing for over ten years and the interested persons are well aware of the issues. EPA 

notes that at least 725 of the 1833 documents (approximately 40 percent, and including both 

technical and economic documents), included in the proposed rule record have appeared in the 

record of previous 316(b) rulemakings. In addition, a significant percentage of record documents 

were publicly available prior to the publication of the proposed rule on April 20, 2011; up to 25 

percent of the record was posted by March 2011, with almost 200 new documents having been 

made available as early as 2009 and over 300 new documents available by the end of 2010. The 

extensive nature of the comments also indicates the adequacy of the comment period. On the 

proposed rule EPA provided a comment period from April 20, 2011 until August 18, 2011 

(which included an extension of 30 days). EPA published the Notice of Data Availability Related 

to Impingement Mortality Control Requirements in the Federal Register (FR) on June 11, 2012, 

and the Notice of Data Availability Related to the EPA Stated Preference Survey on June 12, 

2012. The comments periods for these NODAs closed on July 11 and July 12, 2012, 

respectively, allowing for a 30-day comment period for each publication. 

Even in cases involving complex subjects, courts have routinely held that comment periods of 45 

days and less are reasonable. See, e.g., Connecticut Light & Power Co. v. NRC, 673 F.2d 5252, 

534 (D.C. Cir. 1982)(30-day comment period); Omnipoint Corp. v. FCC, 78 F.3d 620, 629-30 

(D.C. Cir. 1996)(7-day comment period); Florida Power & Light Co. v. United States, 846 F.2d 

765, 772 (D.C. Cir. 1988)(15-day comment period); North Am. Van Lines v. ICC, 666 F.2d 

1087, 1092 (7th Cir. 1981)(45-day comment period); Phillips Petroleum Co. v. EPA, 803 F.2d 

545, 558-59 (10th Cir. 1986)(45-day comment period). Comment periods are deemed reasonable 

Essay 6 7 
where, as here, the public comments were numerous and extensive, and the comments had an 

effect on the final agency action. 

In response to particular comments about the ability to comment on benefits of the rule, EPA 

disagrees that the public had been denied the opportunity to comment on actual monetized 

benefits of proposed rule. As explained in the preamble to the final rule, EPA did not use the 

results of the stated preference survey in the final rule; EPA has not accounted for values 

estimated from the survey in the quantitative comparison of costs and benefits. EPA notes that 

the stated preference survey instrument was also provided for public comment under a separate 

Federal Register notice and Information Collection Request (ICR). Please refer to Essay 77 and 

the preamble for the final rule for further discussion of EPA’s inclusion of the stated preference 

survey results in the benefits analysis in the final rule. 

With respect to the final 12-month percent survival IM performance standard, EPA provided the 

analytical approach that it used in calculating it as well as all of the studies that EPA considered 

in developing the standard in the public docket for the proposed rule (including the NODA). See 

Essay 16A. As such, EPA has provided all of the necessary materials for the public to review the 

calculation of the 12-month percent survival IM performance standard in the final rule, and 

additional opportunities for comment are not appropriate. 

In response to comments concerning the schedule for taking final action, the schedule is 

governed by a settlement agreement that resolved two separate mandatory suits against the 

Agency. It is in the public interest for EPA to agree to a deadline for final action in order to 

resolve the disputes at issue in the two suits given that EPA had originally agreed to a courtordered deadline through a consent decree to conduct rulemaking in three Phases in the late 

1990s. EPA has amended the settlement agreement several times in order to accommodate 

additional time needed for the final rule. 

EPA Complied with EO 13563

EPA disagrees with one commenter that the Agency has not adequately complied with the Office 

of Management and Budget’s Executive Order 13563 implementation guidance regarding public 

participation. EPA conducted the rulemaking process in accordance with the standard of 

“transparency” prescribed by Executive Order 13563. As such, EPA has established an official 

public docket for this action under Docket ID EPA-HQ-OW-2008-0667. The official public 

docket consists of the documents specifically referenced in today’s rulemaking action, any public 

comments received, and other information related to this action. Confidential business 

information and other information, the disclosure of which is restricted by statute, are a part of 

the official record for the rule, though this information is not available in the public docket. The 

Agency made every effort possible to accommodate requests for confidential and copyrighted 

information used in this rulemaking consistent with law. Given the longstanding discussions of 

issued related to 316(b) over many years, sufficient time was provided for the regulated 

community to review and comment on these materials and their potential effects on EPA’s 

selection of regulatory options. EPA has made substantial efforts to help explain the complex 

issues involved with 316(b), and conducted a great deal of public outreach, including responding 

to comments, creating a publicly available record, and hosting meetings and conference calls 

with stakeholders. This outreach is detailed in section III.A (76 FR 22184) of the preamble for 

Essay 6 8 
the proposed rule, in the Essay 58, and in the preamble and record for the final rule. EPA 

responded to information requests and has made every effort possible to provide assistance to the 

public to access and understand data used, to the extent allowed by the confidential business 

information requirements at 40 CFR Part 2, to support today’s final rule. 

Essay 6 9 
Essay	 	 	 7: Seafood Processing,	 	 	 	 	 	 	 	 Offshore Oil and Gas, and LNG Terminals

In the proposed rule, NODAs, as well as the TDD for the proposed and final existing facilities 

rule, EPA provides descriptions of the power generation industry and sectors of the 

manufacturing industry and how compliance requirements, technologies, and costs apply to each. 

This essay addresses public comments regarding the entities regulated by today’s rule that are 

not addressed in other essays. 

One commenter noted that some smaller electric utilities more closely resemble manufacturing 

companies in terms of cooling water characteristics than larger electric utilities. EPA has 

determined there are not significant differences between generators and manufacturers with 

respect to the design and functionality of cooling water intakes. See Essay 14 for a more detailed 

discussion on this topic. 

Another commenter was concerned that the proposed rule did not adequately state that only 

offshore seafood processing facilities, not onshore facilities, are exempt from the rule. The 

EPA’s final action regarding existing offshore oil and gas facilities, seafood processing facilities 

and LNG import terminals is the same as EPA proposed (76 FR 22195). Such facilities are 

subject to 316(b) on a best professional judgment basis. The EPA already addressed new 

offshore oil and gas facilities, seafood processing facilities and LNG import terminals in the 

Phase III rule. EPA did not propose any changes for such new facilities, nor did EPA reopen the 

Phase III rule for new offshore facilities. Some commenters mistakenly assumed the proposed 

rule (and therefore the final rule) does not apply to existing onshore locations of these types of 

facilities, or commented that onshore facilities should be exempt from any requirements. EPA 

disagrees, noting that such facilities are in scope if they meet the proposed applicability criteria 

in § 125.91. The final rule does not change this position from proposal. For onshore facilities 

lower than the threshold established in today’s rule, such facilities will be subject to 316(b) 

requirements on a case-by-case, best professional judgment basis. The final regulatory language 

at § 125.91(d) reflects this intent. The preamble to today’s final rule explains that EPA is not 

including existing offshore oil and gas facilities, offshore seafood processing facilities, and 

offshore liquefied natural gas import terminals; a summary of EPA’s rationale follows. 

In the Phase III rule, EPA studied offshore oil and gas facilities and offshore seafood processing 

facilities and could not identify any technologies (beyond the protective screens already in use) 

that are technically feasible for reducing impingement or entrainment in such existing facilities. 

As discussed in the Phase III rule preamble, known technologies that could further reduce 

impingement or entrainment would result in unacceptable changes in the envelope of existing 

platforms, drilling rigs, mobile offshore drilling units, offshore seafood processing facilities, and 

similar facilities as the technologies would project out from the hull, potentially decrease the 

seaworthiness, and potentially interfere with structural components of the hull. It is also EPA’s 

view that for many of these facilities, the cooling water withdrawals are most substantial when 

the facilities are operating far out at sea and, therefore, not withdrawing from a water of the 

United States. EPA is aware that LNG facilities may withdraw hundreds of million gallons per 

day of seawater for warming (re-gasification). However, some existing LNG facilities might still 

withdraw water where 25 percent or more of the water is used for cooling purposes on an actual 

Essay 7 10 
intake flow basis. EPA has not identified a uniformly applicable and available technology for 

minimizing impingement mortality and entrainment at these facilities, nor did commenters 

provide any new data or information upon which the EPA could establish uniform requirements 

for all such facilities. Any existing facility with a NPDES permit and that withdraws any volume 

of water for cooling purposes, but that is not subject to the national BTA standards under today’s 

final rule, is subject to site-specific, BPJ BTA determinations. 

For additional discussion on this topic, also see Essay 14. 

Essay 7 11 
Essay	 	 	 	 	 	 8: Purpose of the NODAs, Introduction

This essay addresses the public comments received regarding the purpose of the two notices of 

data availability (NODAs) that further clarified EPA’s approach to today’s final existing 

facilities section 316(b) rule. Most of these comments responded to the Notice of Data 

Availability Related to Impingement Mortality Control Requirements published on June 11, 

2012. A few comments addressed in this essay referenced the Notice of Data Availability 

Related to the EPA Stated Preference Survey published on June 12, 2012, but none made 

substantive comments on this NODA. Essay 77 responds to substantive comments received 

related to the Stated Preference Survey. All of the comments addressed in this essay were 

submitted by industry stakeholders except for one comment from an environmental organization. 

Nine of the commenters (all industry commenters) expressed approval with EPA for considering 

additional information/soliciting comment on these topics to increase compliance flexibility for 

impingement mortality control. One commenter (Riverkeeper) was against any revisions that 

would decrease stringency from the compliance options outlined in the proposed rule. Also, 

many of these comments provided introductory material (in-text editorial or summary remarks 

that did not contain substantive content) to substantive comments or summarized the purpose of 

the NODA. These commenters proceeded to detail their specific issues in later comments that are 

addressed in other essays responding to comments. 

Notice of Data Availability Related to Impingement Mortality Control Requirements

This NODA described flexibilities EPA considered for the impingement mortality control 

requirements post-proposal. EPA notes that the final rule includes flexibility to comply with the 

national BTA standard for impingement mortality by including seven alternatives which EPA 

has determined will meet or exceed the performance of the BTA technology. See the preamble 

for additional discussion. Please refer to Essay 16A and the preamble for the final rule for 

discussion of EPA’s consideration of additional data in its calculation of the final 12-month 

percent survival IM performance standard. Essay 16 and the preamble for the final rule also 

address Riverkeeper’s concern that the final rule would be less stringent than the proposed rule. 

Essay 8 12 
	 	 	 	 	 	

                                                            

Essay 10: Legal Authority, Purpose, and Background

The final rule implements section 316(b) of the CWA for existing facilities. Section 316(b) 

provides that any standard established pursuant to section 301 or 306 of the CWA and applicable 

to a point source must require that the location, design, construction and capacity of cooling 

water intake structures (CWISs) reflect the best technology available (BTA) for minimizing 

adverse environmental impact. The final rule also makes limited amendments related to the 

Phase I CWA section 316(b) rule for new facilities (consisting of two technical corrections and 

removal of restoration provisions; see preamble for details). The final rule establishes 

requirements that represent BTA for minimizing adverse environmental impacts that EPA has 

identified as associated with CWISs, including impingement mortality and entrainment. EPA has 

previously implemented section 316(b) on a site-specific basis for existing facilities and issued a 

new facility rule in 2001. The preamble to the final rule provides a detailed discussion of the 

legal authority, purpose, and background of the final 316(b) existing facility rule. 

Some commenters asserted that EPA’s application of the rule to existing facilities lacks a basis in 

the CWA, and that section 316(b) only authorizes a one-time, preconstruction review of CWIS 

location, design, construction, and capacity. 

EPA disagrees with both points. There is no support in the language of section 316(b) indicating 

that it applies only to new facilities. The statutory language refers to point sources, and cross 

references the technology standards applicable to existing sources (section 301) and new point 

sources (section 306). Thus it is reasonable for EPA to interpret section 316(b) as applicable to 

existing facilities. Since the CWA provision was adopted in 1972, EPA has been applying 

section 316(b) to existing as well as new facilities or new sources.1

 Section 316(b) requirements 

apply in part to standards established under CWA section 301, and section 301 requires 

establishment of effluent limitations guidelines for existing facilities. Thus, EPA has authority to 

apply 316(b) requirements to existing facilities. EPA has fully explained its interpretation of its 

authority previously (see 69 FR 41629), and the Second Circuit has upheld EPA’s interpretation 

of the CWA. Riverkeeper, Inc. v. USEPA, 475 F. 3d 83, 121-122 (2nd Cir. 2007). The Supreme 

Court did not grant cert on this issue. The basis for the final rule is fully discussed in the legal 

authority and basis sections of the preamble to the final rule. 

Some commenters asserted that EPA is only allowed to regulate the four statutory elements of 

CWISs specified in section 316(b) and that, with regard to any standard for impingement 

mortality, the CWA doesn’t permit the imposition of a performance standard. Other commenters 

argued that EPA lacks the authority to require existing facilities to retrofit to closed-cycle 

cooling or to dictate when or how a facility can operate. They observed that the installation of 

cooling towers can require extensive redesign and reconstruction of an existing facility, which 

the statute does not authorize EPA to require. They also asserted that closed-cycle cooling is not 

a CWIS technology and cannot be required under 316(b). 

1

 A new source is a source for which a 306 new source performance standard is applicable. New facilities are a set of 

facilities as defined in EPA’s Phase I new facility rule. The terms are not synonyms. 

Essay 10 13 
EPA does not agree that the language of section 316(b), including the four elements associated 

with CWISs described in the statute (i.e., CWIS location, design, construction and capacity), 

limit the approaches EPA can take to regulation of cooling water intakes or limits the standards 

to the four aspects of CWISs identified in the statute as long as a requirement minimizes 

impingement and or entrainment of the cooling water intake. In Entergy, the Supreme Court 

stated that “As we have described, § 1326(b) instructs the EPA to set standards for cooling water 

intake structures that reflect “the best technology available for minimizing adverse 

environmental impact.” In Riverkeeper I, the Second Circuit held that “the statute allows the 

EPA to regulate the operation of cooling water intake structure, as the word ‘design’ can 

reasonably be read to embrace the methods used in running a structure as well as its physical 

layout and technical specifications.” 358 F.3d 174, 198 (2nd Cir. 2004). EPA often uses 

performance standards to provide maximum flexibility to the regulated community with regard 

to how they choose to meet applicable requirements. Here, EPA’s BTA impingement mortality 

standard represents permissible regulation of CWIS design and capacity. EPA would note that 

this rule does not require all existing facilities to retrofit to closed-cycle cooling or dictate what 

technologies a facility must adopt to meet the IM standard or when or how a facility may 

operate. Rather, for impingement mortality, the BTA standard requires compliance with one of 

seven alternatives, one of which includes use of a closed-cycle recirculating system. For 

entrainment, the rule adopts a site-specific approach except for new units. New units are subject 

to requirements based on closed-cycle cooling, but such new units typically do not involve 

retrofitting. With regard to the rule’s inclusion of closed-cycle cooling (or the reduction in 

entrainment comparable to closed-cycle cooling) as the basis for new unit requirements, EPA has 

established and continues to maintain that flow volume is one aspect of the “design” and 

“capacity” of a CWIS and, as such, it may be addressed under 316(b). (See the discussions of 

EPA authority at 66 FR 65313-65314 (Phase I); and 69 FR 41629-41630 (Phase II).) The Phase I 

rule requirements are based in significant part on reductions in flow volume and that rule (except 

for restoration) was upheld by the Second Circuit in Riverkeeper v. EPA, 358 F.3d 174 (2nd Cir. 

2004). 

Environmental commenters including Riverkeeper, Inc., Natural Resources Defense Council, 

Sierra Club, Waterkeeper Alliance, Earthjustice, Environmental Law and Policy Center, Clean 

Air Task Force, Network for New Energy Choices, California Coastkeeper, Alliance, 

Soundkeeper, Inc., Delaware Riverkeeper Network, Save the Bay – Rhode Island, Friends of 

Casco Bay, NY/NJ Baykeeper, Hackensack Riverkeeper, Santa Monica Baykeeper, San Diego 

Baykeeper, Scenic Hudson, American Littoral Society, and Conservation Law Foundation 

(hereafter referred to as Riverkeeper) took a contrary view to the comments against the use of 

closed-cycle cooling presented above and maintained that in amending the CWA Congress was 

aware of the damage caused by once-through cooling, that EPA must establish BTA standards 

based on closed-cycle cooling , and the amended CWA establishes a technology-forcing 

framework that requires per Congress’s specific intent uniform standards based on the 

performance of optimally operating plants (citing Kennecott v. EPA, 780 F. 445, 448 (4th Cir. 

1985)). Riverkeeper further commented and cited cases in support of the assertion that it is 

permissible for BTA to have economic impacts and that standards are economically achievable 

even if they result in a high rate of closure. Other commenters asserted that EPA’s 316(b) 

requires BTA, which consists of closed-cycle systems, and as such most power plants are in 

violation of the CWA. 

Essay 10 14 
                                                            

 

 

EPA agrees that, in establishing section 316(b) requirements, EPA should take account of 

Congress’ technology-forcing objectives. See Entergy, 556 U.S. 208, 235 (2009), J. Breyer 

concurring.2

 EPA also agrees that BTA regulations may impose some economic costs on a 

facility but does not agree that section 316(b) mandates closed-cycle systems for all existing 

facilities. As discussed in the preamble, the language of section 316(b) is silent regarding 

specifically how stringently cooling water intake structures must be controlled, only that their 

adverse environmental impacts be “minimized” and the Supreme Court has held that this gives 

EPA discretion to consider many factors. See Entergy, 556 U.S. at 2223 in establishing 316(b) 

standards. And a standard that requires the establishment of BTA entrainment requirements in a 

site-specific proceeding fulfills EPA’s mandatory duty to implement section 316(b) as held by 

the court that entered the original consent decree in the original mandatory duty case. Cronin v. 

Browner, 898 F.Supp. 1052, 1062 (In rejecting Intevernors’ opposition to entry of the decree on 

the grounds that it would force EPA to propose generally applicable rules, thereby precluding 

EPA from determining that controls should be determined on a case-by-case basis, the Court 

disagreed saying “under the decree EPA could, if otherwise appropriate, propose and issue 

regulations that do not embody a generally applicable rule.”) Based on the ambiguous language 

of 316(b) and its limited legislative history, EPA does not agree that Congress has expressed a 

clear and specific intent that 316(b) requirements must be expressed only as uniform national 

categorical technology-based standards. In Entergy, the Supreme Court held that the silence in 

section 316(b) conferred discretion on the Agency, not a prohibition to consider any particular 

factor. 

Nothing in the CWA requires EPA to abandon a site-specific approach to 316(b) standardsetting. As the Second Circuit has made clear in the new facility Phase I rule, the agency was 

upheld on a case-by-case approach to standards for those facilities below the rule’s 2 mgd DIF 

applicability. The court stated that 316(b) “...does not compel the EPA to regulate either by one 

overarching regulation, or based on categories of sources ... or on a case-by-case basis...” 

Riverkeeper, Inc. v. USEPA, 358 F. 3d 174, 203 (2nd Cir. 2004). The court went on to observe 

that “[t]he Clean Water Act does not forbid the EPA from addressing certain environmental 

problems on a case-by-case basis where categorical regulation is not technologically feasible, or 

when it does not violate the statute’s language and is otherwise consistent with Congress’s 

overriding goal of improving the quality of the nation’s waters” (internal citation omitted here). 

Riverkeeper, Inc. v. USEPA, 358 F. 3d at 203. This rule determines BTA for existing facilities 

and new units at existing facilities. Such BTA is based on the most effective technologies 

available to the extent that EPA was able based on the record to identify such technologies. As 

explained generally in the basis section of the preamble to this final rule, closed-cycle cooling is 

2

 “The EPA’s reading of the statute would seem to permit it to describe environmental benefits in non-monetized 

terms and to evaluate both costs and benefits in accordance with its expert judgment and scientific knowledge. The 

Agency can thereby avoid lengthy formal cost-benefit proceedings and futile attempts at comprehensive 

monetization, see 69 Fed. Reg. 41661-41662 (2004); take account of Congress’ technology-forcing objectives; and 

still prevent results that are absurd or unreasonable in light of extreme disparities between costs and benefits. This 

approach, in my view, rests upon a “reasonable interpretation” of the statute--legislative history included. Hence it is 

lawful.” 

3

 “The inference that respondents and the dissent would draw from the silence is, in any event, implausible, as § 

1326(b) is silent not only with respect to cost-benefit analysis but with respect to all potentially relevant factors. If 

silence here implies prohibition, then the EPA could not consider any factors in implementing § 1326(b) --an 

obvious logical impossibility. It is eminently reasonable to conclude that § 1326(b)’s silence is meant to convey 

nothing more than a refusal to tie the agency’s hands . . .” 

Essay 10 15 
not the best technology available for existing facilities on a national basis based on consideration 

of all relevant factors. As described in the option selection discussion in the preamble, while 

EPA did consider costs, costs were not a dispositive factor in the decision to reject closed-cycle 

cooling as the basis for a uniform national BTA standard. EPA did not reject closed-cycle 

cooling here either because it was not economically achievable or because the costs of closedcycle would exceed its benefits. Instead, EPA rejected closed-cycle cooling as the technology 

basis for a uniform national BTA entrainment standard based on a combination of three factors: 

land availability, air emissions, and remaining useful plant life. Further, once EPA has found that 

a “one-size-fits-all” approach is not feasible, it is appropriate to assess the required controls on a 

site-specific basis, including a consideration of costs and benefits. See Entergy 556 U.S. at 225-

226, “But whether it is “reasonable” to bear a particular cost may well depend on the resulting 

benefits; if the only relevant factor was the feasibility of the costs, their reasonableness would be 

irrelevant.” 

Based on the performance capabilities of closed-cycle cooling, this rule does include closedcycle cooling as a compliance alternative and the rule requires new unit performance to be 

consistent with closed-cycle cooling systems for the reasons explained in the preamble. 

Riverkeeper in comments further argued that EPA’s interpretation of “available” is unlawful 

because it is not permissible for EPA to reject any technology because it is not available to all 

facilities (citing 76 FR 22,203), as well as that EPA impermissibly rejected closed-cycle cooling 

as BTA and 0.5 ft/sec as a national impingement mortality standard because these were not 

available at all facilities. 

EPA does not agree with these comments. As discussed in the proposed (76 FR 22196-22212) 

and final rule (see the legal authority and basis sections) preambles, EPA considered many 

factors in determining the BTA standards, including availability, feasibility, efficacy, costs 

(including economic impacts), and the location, age, size, and type of facility, as well as nonwater quality effects of various technologies on energy production and availability, electricity 

reliability, and potential adverse environmental effects. EPA’s consideration of these factors 

reflect the Agency’s authority under section 316(b) and, as discussed in the proposed and final 

rule preambles, EPA has considerable discretion in balancing these factors. EPA has explained in 

the basis section of the preamble to the final rule that closed-cycle cooling is not the best 

technology available on a national basis because of land availability, increased air emissions and 

remaining useful life. Low velocity is also not the best technology available for reducing 

impingement mortality because it is not widely available. As noted, however, closed-cycle 

cooling is one of several technologies included to meet the impingement mortality standards of 

the rule, as is low velocity. 

Riverkeeper comments maintained that regulation on a case-by-case basis has resulted in 

industry using its resources to overwhelm regulators, and assert that the case-by-case approach 

has generally prevented, delayed and weakened regulation, and ultimately perpetuated a status 

quo that is contrary to the goals of the CWA and requirements of 316(b). Riverkeeper comments 

suggested the case-by-case approach is arbitrary because it perpetuates an ineffective approach 

and that EPA’s approach is not consistent with Congress’s shift in focus in the CWA (and earlier 

water protection laws) from water quality to technology-based standard setting. 

Essay 10 16 
The final rule establishes BTA standards for impingement mortality and entrainment on a 

national basis. After careful analysis, EPA did not identify one technology or a combination of 

technologies that could or should uniformly be established as the technology basis for all 

facilities to minimize entrainment at existing facilities (see TDD Chapter 5). Consequently, EPA 

did not base the BTA standard for entrainment on a specific technology or technologies. See the 

preamble to the final rule. 

As explained in EPA’s option selection discussion in the preamble, for entrainment, there are a 

number of factors that make no one technology appropriate for all cooling water intakes. In many 

instances, technologies are simply not widely available. And since implementation of the Phase 

II rule that was remanded by the Second Circuit, EPA has learned that many of technology basis 

for that rule’s entrainment requirements are not as effective as once thought for minimizing 

entrainment (see 76 FR 22185 discussing entrainment exclusion versus entrainment survival). 

Also see Section VI.E in today’s preamble. The Phase II rule in large part was based on EPA’s 

conclusion that there were, in addition to closed-cycle cooling, a number of other technologies 

that would achieve reductions in entrainment that were comparable to that achieved by closedcycle cooling. Consequently, EPA required compliance with closed-cycle or achievement of a 

performance equivalent to that technology. As explained in the final preamble, since the Phase II 

rule, EPA has learned that the gap between the performance of the most effective entrainment 

reduction technologies (closed-cycle) and other less expensive technologies has widened 

significantly. Also see Essay 18. In the Phase II rule, EPA identified a suite of intermediate 

performing technologies that could be used to reduce entrainment. This suite of technologies 

included a wide variety of fine mesh exclusion technologies such as traveling screens, 

wedgewire screens and other passive screens, and filter barriers. While available performance 

data for entrainment reduction at that time were not as comprehensive as impingement data, EPA 

found that fine mesh wedgewire screens and fine mesh traveling screens have been shown to 

reduce entrainment compared to once-through cooling systems by 60 to 90 percent. EPA 

acknowledged that screening to prevent entrainment may cause impingement of those organisms 

instead. 69 FR 41599. 

Since the final Phase II rule (2004) EPA has obtained additional performance data including 

studies documenting the survival of entrainable organisms that were impinged, or “converts.” 

First, EPA found an average of 87 percent exclusion of eggs could be achieved by fine mesh 

screens of 0.5 mm slot size. The available data shows mesh sizes of 2.0 mm or greater were 

found to have no effect on exclusion of eggs. In response to comments, industry provided data 

showing limited select species of fish may have eggs near the 2.0 mm size. While EPA 

appreciates the data, the record still shows the overwhelming majority of eggs are collected by 

0.5 mm mesh, and a negligible quantity of eggs are collected on a 2.0 mm mesh (see Essay 16 

for more details). As discussed in the TDD Chapter 6, fine mesh is not feasible for many 

facilities, as replacement of coarse mesh by 0.5 mm fine mesh would require an increase in 

screen area of 5.2 to 10.3 times depending on intake velocity. Second, EPA found the 

performance of fine mesh screens to be generally poor for larvae, ranging from 15 to 23 percent 

exclusion, and with an average survival rate of roughly 10 percent. See TDD Chapter 6.2 for 

more information. EPA further found that intake velocity alone had low impact on survival of 

eggs and larvae because such early life stages have no avoidance response, little or no skeletal 

structure, and lack capability for mobility. In other words, eggs can’t swim. Some commenters 

have hypothesized that low intake velocity could set up flow gradients where eggs are diverted 

Essay 10 17 
around the CWIS. EPA disagrees, first noting that the density of eggs is so close to that of water 

that differential flow patterns are improbable. Second, based on technical survey data, the 

average intake velocity and intake volume are both sufficiently large that any diversion through 

differential flow would be irrelevant. However, to date EPA is not aware of any real data 

supporting the theory, and the commenter’s theory is therefore rejected. In summary, EPA found 

that there are no high-performing or intermediate-performing technologies on which to base 

national entrainment requirements, and no entrainment control technologies that are widely 

available and feasible. 

There is a second additional consideration that further required EPA to focus renewed attention 

on how widely available closed-cycle cooling in fact was. The Second Circuit decision in the 

Phase II rule removed restoration as a compliance option that EPA could consider. The decision 

underscored that restoration measures – one compliance option included in the Phase II rule – 

were not an available tool for complying with any 316(b) standard. However, at the time of the 

Phase II promulgation, EPA expected some facilities would use restoration in lieu of closedcycle cooling, thus making closed-cycle or reductions commensurate with closed-cycle feasible 

(76 FR 41609). With the court decisions that restoration was not an available tool for 

compliance, compliance with a standard based on closed-cycle cooling alone is thus less feasible 

than EPA had expected at the time of the Phase II promulgation. 

The changed landscape has narrowed markedly EPA’s range of options with respect to the 

technology basis for today’s BTA standards. The gap between the performance of the most 

effective entrainment reduction technologies (closed-cycle) and other less expensive 

technologies has widened significantly. EPA’s narrowed range of compliance technology 

choices required EPA to look even more closely at the feasibility of closed-cycle cooling and 

reduced flow. As the Second Circuit has noted, EPA is clearly entitled to make its choice among 

alternative BTA technologies based on more factors other than just a technology’s effectiveness 

in reducing impingement and entrainment. id. at 196. As noted, EPA has identified a 

combination of three factors as significant in its decision to reject closed-cycle cooling as the 

sole technology basis for a national BTA entrainment standard. Given that EPA has not 

identified a technology or combinations of technologies that EPA concluded is “best technology 

available” for minimizing entrainment at existing units, EPA has determined that a site-specific 

approach to regulating these facilities considering all relevant factors is the best solution for 

implementing section 316(b). Thus, to the extent possible based on the record, EPA has 

established national requirements that implement section 316(b). 

EPA acknowledges that implementing aspects of the 316(b) regulations on site-specific basis 

presents certain challenges but does not agree that such an approach is ineffective. EPA adopted 

its BTA entrainment standard because it concluded that the appropriate way to determine that 

BTA entrainment requirements for a particular facility is after a structured, site-specific analysis 

of a number of factors, including, but not limited to, technical feasibility, costs, benefits, and 

non-water quality environmental impacts. Consequently, the final rule at 40 CFR 125.98(f)(2) 

requires the Director to consider, among other factors, the number and type of entrained 

organisms, technical feasibility, impact of changes in particulate emissions, land availability, 

remaining useful plant life and quantified social benefits and costs in determining appropriate 

BTA entrainment requirements. In addition, under 40 CFR 125.98(f)(3), the Director may 

consider other factors in establishing BTA entrainment requirements such as thermal discharge 

Essay 10 18 
impacts, impacts on reliability of energy deliveries in the immediate area and others to the extent 

the permit applicant submitted information on these. The final rule establishes a structure for 

decision-making, information requirements, decision criteria, schedule and an overall process for 

assessing entrainment that will serve to guide permittees and permitting authorities in 

implementing the rule requirements and as a result EPA expects that the BTA standard’s sitespecific requirements can be implemented effectively. Additionally, EPA can develop additional 

guidance if necessary as rule implementation goes forward. 

EPA is not responding here to each of the 46 “incorrect” arguments the comment indicates 

industry puts forth as part of 316(b) permitting because these arguments do not address specific 

aspects of the final rule but appear to address 316(b) permitting prior to this rule, but notes that 

this rule, provides a structured, transparent and fair way for all of the arguments presented by the 

commenters to be assessed by the permitting authority and will require the permitting authority 

to explain the factors that led to the permitting decision. EPA notes that some of these arguments 

pertain to section 316(a), which is not addressed in this rule. Also, EPA has tried, to the extent 

possible under a case-by-case approach, to shift the workload from the permitting authority. For 

example, for existing facilities that withdraw greater than 125 mgd AIF, the rule requires peer 

review of the technical feasibility and cost study, the benefits valuation study, and the non-water 

quality environmental and other impacts study to ensure their accuracy. Finally, EPA does not 

agree that this rule is so similar to the water quality approach used prior to the current CWA as to 

be ineffective. This rule specifies technology-based performance where reasonable and for sitespecific determinations includes detailed information and performance requirements, as well as a 

decision-making process, evaluation criteria, and documentation requirements all of which is 

subject to NPDES public participation and administrative provisions. In addition, given the 

unique focus and objective of section 316(b) the rule’s requirements will make clear to the 

permitting authority the environmental impacts posed by the particular CWIS at issue along with 

the costs of technologies and other relevant factors at the site. 

Some commenters stated that, as proposed, impingement mortality requirements apply even if a 

facility has or proposes closed-cycle cooling. The commenters asserted that this appears 

unnecessary and redundant, since a closed-cycle cooling system will reduce impingement 

mortality and should constitute BTA. These concerns are addressed in the final rule. The final 

rule provides that a properly operated closed-cycle recirculating system meets the impingement 

mortality requirements. 

Commenters also expressed some concerns regarding the definitions of certain terms. Some 

asserted that EPA’s expansion of the definition of cooling water intake structure (CWIS), by 

saying that the CWIS extends up to and including “but not limited to” the intake pumps, results 

in a definition that is unlimited (i.e., could include the entire facility), is not explained (it is 

characterized as the same as the Phase I definition). Additionally, some commenters observed 

that the proposed definition of closed-cycle recirculating system (CCRS) is different than and far 

more restrictive than the definition used in the Phase I rule and thus us inconsistent with that 

definition and confusing. Commenters noted that the definition of CCRS includes only systems 

that withdraw makeup flow intermittently, are designed to operate above minimum cycles of 

concentration, reduce flow by a specified percentage (depending on whether salt of fresh water), 

and do not include cooling ponds that are waters of the U.S. These concerns are addressed in the 

Essay 10 19 
final rule. The final definition of CWIS mirrors the Phase I rule and does not include the “but not 

limited to” language. 

With regard to the definition of CCRS, the definition of CCRS in this final rule has changed 

somewhat from proposal. Under 40 CFR 125.92(c)(1), CCRS includes a facility with wet, dry, or 

hybrid cooling towers, a system of impoundments that are not waters of the United States, or any 

combination thereof. A properly operated and maintained closed-cycle recirculating system 

withdraws new source water (makeup water) only to replenish losses that have occurred due to 

blowdown, drift, and evaporation. If waters of the United States are withdrawn for purposes of 

replenishing losses to a closed-cycle recirculating system other than those due to blowdown, 

drift, and evaporation from the cooling system, the definition makes it clear that the Director 

may still determine a cooling system is a closed-cycle recirculating system if the facility 

demonstrates to the satisfaction of the Director that makeup water withdrawals attributed 

specifically to the cooling portion of the cooling system have been minimized. Under 40 CFR 

125.92(c)(2),the definition clarifies that CCRS can include impoundments are not waters of the 

U.S. provided such impoundments were constructed prior to the effective date of the rule and 

must have been constructed for the purpose of a cooling system. The definition specifies 

appropriate documentation of the impoundment’s purpose must be demonstrated to the 

satisfaction of the Director. 

Based on public comments received by EPA, the final rule definition of CCRS does not prohibit 

continuous intake flows of water, as was proposed. EPA’s intent is to make sure that closedcycle systems not just built but then operated as a once through system (with the exception of 

impoundments which must have the project purpose documented as described above). The final 

rule definition does not include the proposed examples of flow reduction percentages (compared 

to a once-through system) and cycles of concentration (for cooling towers) that constitute 

minimized makeup and blowdown for salt and freshwater, respectively. While these examples 

should help permitting authorities assess a variety of cooling systems, and are therefore included 

in the preamble, the key evaluation is that a properly operated and maintained closed-cycle 

recirculating system withdraws new source water (makeup water) only to replenish losses that 

have occurred due to blowdown, drift, and evaporation. The final rule definition states this. The 

final rule definition of closed-cycle cooling also provides the permitting authority with some 

flexibility to determine that a cooling system that needs replenishment for losses other than those 

due to blowdown, drift, and evaporation from the cooling system, still comprises a closed-cycle 

recirculating system provided the facility demonstrates to the satisfaction of the Director that 

makeup water withdrawals attributed specifically to the cooling portion of the cooling system 

have been minimized. EPA concluded that these clarifications help define when cooling systems 

constitute a CCRS. 

EPA received comments from Riverkeeper asserting that the Agency has a duty, under the 

Endangered Species Act (ESA) to consult with the Departments of Interior and Commerce to 

ensure that the 316(b) rule “is not likely to jeopardize the continued existence of any threatened 

and endangered (T&E) species or result in the destruction or adverse modification of critical 

habitat of such species.” This essay responds to Riverkeeper’s comments. 

Under section 7 of the Endangered Species Act, each Federal Agency must insure that any action 

authorized, funded, or carried out by the agency “is not likely to jeopardize the continued 

Essay 10 20 
existence of any endangered species or threatened species or result in the destruction or adverse 

modification of habitat of such species which is determined by the Secretary, after consultation 

as appropriate with affected States, to be critical. . . .” In the case of any agency action that is 

likely to jeopardize an endangered species or result in destruction of critical habitats, the agency 

must consult with the concerned offices with responsibilities under the ESA, in particular, the 

National Marine Fisheries Services (NMFS) and the U.S. Fish and Wildlife Services (FWS) 

(collectively referred to as the Services). 

In compliance with its obligations under the ESA, in July 2012, EPA began informal 

consultation with the NMFS about its proposed section 316(b) regulations. In October 2012, 

EPA began informal consultation with the FWS. As part of the informal consultation, EPA 

prepared a draft biological evaluation of the effects of this rule on T&E species. EPA concluded 

in the draft biological evaluation that the rule was not likely to adversely affect listed species or 

designated critical habitat due to the many beneficial effects on species, and concluded that the 

rule was not likely to adversely affect listed species or designated critical habitat. EPA, however, 

did not receive the Services’ concurrence with the Agency’s “not likely to adversely affect” 

finding. Consequently, on June 18, 2013, EPA requested formal consultation with the Services 

and submitted a final biological evaluation. 

The Services’ final biological opinion found that the rule will not jeopardize the continued 

existence of threatened or endangered species or destroy or adversely modify a critical habitat. 

The final biological opinion is available in the record for today’s rule. 

For additional information about the elements of the rule that protect listed species, please see 

the “Memorandum to the Record of EPA’s Final Regulations to Establish Requirements for 

Cooling Water Intake Structures at Existing Facilities and Amend Requirements at Phase I 

Facilities” (DCN 12–4543). 

Finally, some commenters suggested that it is inappropriate to automatically give endangered 

and threatened species elevated status and consideration under the rule and that benefits to any 

threatened and endangered species should not be considered. These commenters argued that EPA 

has no basis for incorporating ESA requirements into the rule and regulating ESA species under 

the NPDES program (they maintained that the ESA operates independently). 

EPA disagrees with these commenters. As threatened and endangered species and designated 

critical habitat (e.g., prey base) are among the species that can be impinged and entrained, EPA 

considers threatened and endangered species and designated critical habitat as relevant factors in 

case-by-case decision-making under section 316(b). EPA is not requiring state NPDES Directors 

to undergo ESA consultation for permit issuance; however, a fair consideration of costs and 

benefits by permitting authorities should include a consideration of the effects of impingement 

and entrainment on listed species and designated critical habitat (e.g., prey base). Protecting 

those species is a relevant benefit of controls. The rule does not give these species elevated 

status, but requires the permitting authority to consider those effects, along with other 

environmental effects as a relevant factor along with other relevant factors. In addition, the rule 

does not regulate ESA species under the NPDES program; instead, the rule addresses threatened 

and endangered species to the extent necessary to ensure this action is consistent with both the 

ESA, CWA section 316(b) and Administrative Procedure Act requirements. The ESA states that 

Essay 10 21 
Federal agencies shall, in consultation with the Service(s), insure that any action the agency 

authorizes, funds, or carries out is not likely to jeopardize any threatened or endangered species 

or result in the destruction or adverse modification of critical habitat. EPA consulted with the 

Services on this Federal action and as the Services concluded in their joint Biological Opinion, 

today’s rule is not likely to jeopardize the continued existence of listed species or result in the 

destruction or adverse modification of designated critical habitat. As explained earlier, section 

316(b) provides that any standard established pursuant to section 301 or 306 of the CWA and 

applicable to a point source must require that the location, design, construction and capacity of 

CWISs reflect the BTA for minimizing adverse environmental impact. Impingement and 

entrainment mortality have the potential to harm and kill threatened or endangered species and 

such impacts are clearly adverse environmental impacts, particularly given the protected status of 

these species. EPA’s rule will be subject to the Administrative Procedure Act’s standard of 

review - whether the rule is arbitrary, capricious, an abuse of discretion, or otherwise not in 

accordance with law. Therefore the provisions of the rule related to species exist to set forth a 

framework for decision-making that includes listed species and designated critical habitat as a 

relevant factor in case-by-case decision-making. 

Essay 10 22 
Essay 11: Proposed Amendments Related to the Phase I Rule

Introduction

Today’s existing facility 316(b) final rule removes the restoration-based compliance alternative 

and the associated monitoring and demonstration requirements from the Phase I, new facility 

rule, and does not include restoration as a compliance alternative for existing facilities subject to 

regulation under section 316(b). These actions are based on the Second Circuit Court of Appeal’s 

decisions in Riverkeeper, Inc. v EPA, 358 F.3d 174 (2nd Cir., 2004) and Riverkeeper, Inc. v EPA, 

475 F.3d 83 (2nd Cir., 2007), both of which held in relevant part that EPA exceeded its authority 

by allowing Phase I (new facilities) and Phase II (large power producers) facilities to comply 

with section 316(b) through restoration measures. 

Under compliance Track II in the Phase I (new facility) rule, a facility has the option of 

demonstrating to the Director that the control measures it employs will reduce the level of 

adverse environmental impact (AEI) caused by its cooling water intake structures (CWISs) to a 

comparable level to what would be achieved by meeting the Track I requirements. As part of this 

demonstration, Track II previously allowed a facility to make use of restoration measures. 

Today’s rule removes that portion of 40 CFR 125.84(d)(1) and 125.89(b)(1)(ii) that allow for the 

consideration of restoration measures in demonstrating that impacts under Track II will be 

comparable to Track I. This change to the Phase I rule is based on the Second Circuit Court of 

Appeal’s decision in Riverkeeper, Inc. v EPA, 358 F.3d 174, 191 (2nd Cir., 2004), which found 

that restoration corrects, but does not minimize AEI in the first place, and that it is not 

sufficiently related to the location, design, construction or capacity of CWISs to constitute best 

technology available (BTA). As a result, the Second Circuit held, in relevant part, that EPA 

exceeded its authority by allowing new facilities to comply with section 316(b) through 

restoration measures. The Supreme Court did not address the issue of restoration in Entergy v 

EPA, 556 U.S. 208, 129 S. Ct. 1498 (2009), thus, EPA is bound by the Second Circuit’s decision 

on this issue. Today’s rule also removes 40 CFR 125.86(c)(2)(iv)(C) [evaluation of proposed 

restoration measures], and 125.86(c)(2)(iv)(D)(2) [verification monitoring] since these are 

unnecessary given the removal of the restoration provision from the Phase I rule. Today’s final 

existing facility rule does not include restoration as a compliance alternative for meeting BTA 

for the same reasons that it is being removed from the Phase I rule—EPA lacks authority to 

allow existing facilities to comply with section 316(b) through restoration measures. 

Phase I

Commenters addressed certain aspects of the Phase I rule. Some commenters supported the 

change to the Phase I rule and stated the law is clear and restoration has not worked. Riverkeeper 

commented that it is not appropriate to use 90 percent of the level of performance achieved by a 

closed-cycle recirculating cooling water system as the benchmark for BTA and then allow an 

additional margin of error in measuring compliance with that benchmark. They asserted that a 

facility must aim for 100 percent of the performance level goal and that it would be acceptable if 

they only achieve between 90 and 100 percent of that goal. Other commenters suggested that 

EPA adopt the impingement mortality intake velocity standard and entrainment mortality closedcycle cooling standard as BTA in the Phase I rule. Still other commenters asserted that, although 

Essay 11 23 
EPA indicated that under the proposal the provisions in the Phase I rule associated with 

restoration were removed, § 125.86(c)(2)(ii) has not been removed. 

EPA is removing the restoration provision from the Phase I rule pursuant to the Second Circuit 

decisions discussed above. Comments that it is not appropriate to use 90 percent of the level of 

performance of achieved by a closed-cycle recirculating cooling water system as the benchmark 

for BTA, and that EPA should adopt the impingement mortality intake velocity standard and 

entrainment mortality closed-cycle cooling standard as BTA in the Phase I rule, are beyond the 

scope of today’s final rule. The only aspects of the Phase I rule addressed by today’s final rule 

are those provisions that address the use of restoration as BTA (under Track II). This rule does 

not reopen or alter the BTA standard established in the Phase I rule (EPA notes that the existing 

Phase I rule under Track I includes an intake flow and an intake velocity requirement). EPA 

notes that all other aspects of the Phase I rule were upheld in Riverkeeper, Inc. v EPA, 358 F.3d 

174 (2nd Cir., 2004). With regard to § 125.86(c)(2)(ii), this sub-section has not been removed 

from the Phase I rule since it is not exclusively associated with restoration. 

Restoration for Phase II and Existing Facilities

Some commenters suggested that restoration be allowed in a range of situations, including where 

a nuisance species is a problem that will get worse with the use of CWIS technology, where 

impacted species are not species of concern in man-made lakes, and to reduce the cost of 

meeting 316(b) requirements (i.e., offset losses). 

Given the adverse court decisions in Riverkeeper I and II, EPA is not including restoration as a 

technology for meeting section 316(b) requirements. As discussed in the legal authority and basis 

sections of the preamble to the final rule, the Second Circuit twice found that EPA exceeded its 

authority by allowing facilities subject to 316(b) to comply with section 316(b) through 

restoration measures and, thus, regardless of these situations, EPA lacks authority to identify 

restoration as a compliance alternative for meeting 316(b) requirements. EPA notes that this rule 

does not focus on species of concern and that the impingement and entrainment requirements in 

this rule offer sufficient flexibility to address issues such as nuisance species (for example see § 

125.92(b)) in the most effective manner possible. 

Other commenters suggested that for existing facilities, the use of restoration should be allowed 

in conjunction with CWIS technology as a method for meeting the impingement mortality and 

entrainment mortality standards. Suggestions included that EPA allow a state to set or adjust sitespecific impingement mortality standards that consider restoration projects. Commenters 

indicated that such an approach would avoid identifying restoration as CWIS technology (i.e., 

BTA) and would supplement technologies designed to minimize AEI. They maintained that 

restoration could be used to determine the extent of minimization required. In situations where 

impingement levels are low, the rule also could require a fee to fund habitat enhancement or the 

creation of hatcheries. Some commenters observed that a California Supreme Court decision 

(Voices of the Wetlands v. State Water Resources Board, et al., 257 P.3d 81 (August 15, 2011) 

[attached to original comments]) upholds the use of restoration not as BTA but to supplement 

technology and minimize AEI. 

EPA does not agree that it can set standards based on restoration. EPA disagrees with comments 

that the combined use of technology and restoration is consistent with the Second Circuit 

Essay 11 24 
                                                            

decision. EPA acknowledges states may implement such measures in their programs (such as NJ) 

to supplement the final section 316(b) rules; such programs are beyond the scope of this 

rulemaking. EPA has set national impingement mortality requirements based on technologies 

that are well-demonstrated, available, and feasible based on information and data in the 

rulemaking record. As articulated by the Second Circuit, restoration is not a CWIS technology, it 

does not minimize AEI in the first instance, and it is not sufficiently related to the location, 

design, construction or capacity of CWISs to constitute BTA. Even where impingement levels 

are low4, the Second Circuit has made it clear that restoration cannot constitute BTA regardless 

of the rate of impingement. Thus, restoration is not an appropriate basis for complying with 

either the impingement mortality or the entrainment standards. 

Some commenters suggested that, for existing facilities, EPA should allow for restoration as part 

of a cost-benefit site-specific variance or a BTA variance procedure for impingement controls. 

These commenters encouraged EPA to allow for the use of restoration when the costs of meeting 

316(b) requirements are wholly disproportionate to the benefits of doing so. Such commenters 

suggested that EPA provide a variance to those facilities unable to meet the impingement 

mortality requirements without incurring costs that are wholly disproportionate to the benefits of 

meeting the impingement mortality requirements and that such a variance allow for the 

consideration of restoration. They also suggest that EPA include in the rule a variance for 

facilities that have implemented restoration. 

EPA does not agree that it has authority to allow restoration measures. Therefore any standard 

that includes restoration, such as the commenter’s suggested approach in conjunction with a costbenefit variance for impingement controls, is not authorized. EPA does not agree additional 

variances are warranted or necessary. For IM, EPA does not agree that additional variances are 

necessary because there are technologies that are demonstrated, available, and feasible. For 

entrainment at existing facilities, the Director must establish site-specific requirements at § 

125.98(f) after reviewing the information submitted under § 122.21(r) and § 125.95. The 

Director must, under § 125.98(f)(2), consider quantified and qualitative social benefits and costs 

of available entrainment technologies when such information on both costs and benefits is of 

sufficient rigor to make a decision. To the extent the commenter is further suggesting costbenefit be considered as a variance, see Essay 15. For new units and existing facilities, today’s 

final rule at § 125.98(b)(7) allows the Director to establish alternative requirements the same 

way in which Phase I facilities may request alternative requirements. EPA concludes that any 

additional rule-specific variance would be superfluous. 

Commenters also asserted that because under Entergy costs and benefits can be considered in 

determining the requirements that constitute BTA, the 316(b) standards may not actually result in 

application of the very best technology available and, thus, such commenters suggested that 

mitigation should be allowed to fill the gap. Other commenters argued that the Second Circuit’s 

4

 EPA notes that the impingement mortality performance standard in the final rule can apply to both low and highflow in-scope facilities, and that the rule includes provisions that provide for no additional controls in situations 

where the Director finds that based on a review of site-specific data that there is a de minimis rate of impingement. 

EPA expects the provision will be rarely used. In contrast to Phase II where restoration was assumed to be a key 

component of the BTA standards, in today’s final rule cost analysis EPA has not assumed any facilities would 

comply with the BTA standards through the de minimis provision. 

Essay 11 25 
analysis of restoration is incorrect, and the Supreme Court’s Entergy decision provides EPA with 

some discretion to consider restoration as part of BTA. 

EPA disagrees with both points. Today’s rule establishes BTA for existing facilities based on 

EPA’s consideration of all permissible factors, including cost and benefits. A facility subject to 

today’s rule must meet these requirements to the extent applicable and, if it does so, it will fulfill 

the requirements of section 316(b). Whether a state chooses to require restoration measures in 

addition to the requirements of today’s rule is beyond the scope of this rulemaking. The Agency 

does not agree that the Supreme Court’s Entergy decision provides EPA with authority to 

consider restoration as BTA. The only issue reviewed and decided by the Supreme Court in 

Entergy was whether EPA could consider cost and benefits in determining applicable standards 

under 316(b). The issue of restoration was not accepted for review nor decided by the Supreme 

Court and, as a result, EPA is bound by the Second Circuit’s decision with regard to restoration. 

Commenters also asserted that for existing facilities, restoration should be a factor considered in 

the development of case-by-case entrainment standards. Commenters noted that the proposed 

entrainment standard identifies a minimum of nine factors that must be considered, including the 

impact of entrainment on the waterbody, and suggested that EPA should allow restoration to 

address entrainment impacts. Commenters stated that the proposed rule appears to allow for the 

consideration of restoration in the Benefits Valuation Study (§ 122.21(r)(11), see sub-section 

(iii)). They suggested that EPA should state that restoration should be considered in a costbenefit analysis for entrainment reduction, and that the effects of restoration could be a factor 

considered in determining the technologies needed to address entrainment impacts. 

Based on the Second Circuit Court of Appeal’s decisions in Riverkeeper, Inc. v EPA, 358 F.3d 

174 (2nd Cir., 2004) and Riverkeeper, Inc. v EPA, 475 F.3d 83 (2nd Cir., 2007), restoration cannot 

be used as a technology or requirement that is implemented under a NPDES permit to meet the 

BTA standards in section 316(b). This is separate and distinct from requirements to assess 

waterbody conditions and gather data to properly inform decisions regarding case-by-case 

entrainment requirements. Today’s final rule provides for a case-by-case determination of BTA 

for minimizing entrainment. Such a case-by-case determination must reflect “...the Director’s 

determination of the maximum reduction in entrainment warranted after consideration of the 

relevant factors as specified in § 125.98.” One of the factors that may be considered under § 

125.98 is “[e]ntrainment impacts on the waterbody.” This is a reference to the entrainment 

associated with the CWISs at the relevant facility, and the impact such entrainment has on the 

aquatic health of the associated waterbody. Waterbody conditions may further be impacted by 

other uses of the source waterbody. The information requirements included in the rule require a 

description of the condition of the waterbody and, as an appropriate part of that description, 

would identify information regarding past mitigation efforts. Any such restoration or mitigation 

efforts cannot constitute, substitute for, or be a condition of BTA. EPA notes that § 

122.21(r)(11)(iii) [Benefits Valuation Study] requires consideration of mitigation effort 

completed prior to the effective date of the final rule. This is because the focus of this assessment 

and the entrainment-related adverse impact is on the baseline waterbody condition, and therefore 

necessarily includes past mitigation efforts. 

Some commenters requested that EPA clarify that mitigation is permissible outside of the BTA 

determination. 

Essay 11 26 
This comment is beyond the scope of this rule. EPA reiterates that this rule establishes 

requirements for meeting BTA requirements of CWA section 316(b). NPDES permit 

requirements beyond BTA are determined by other aspects of the NPDES program. 

Requirements or provisions beyond those imposed under the NPDES program are not the focus 

of this rule. 

One commenter suggested that that excluding cooling water that is reused from section 316(b) 

requirements under § 125.91(c) and § 125.92 creates a loophole in the rule that is contrary to the 

objectives of section 316(b). This commenter raised this in the context of a desalinization plant 

co-located with a power plant in Carlsbad CA. The commenter asserts that routing water from a 

desalinization plant to a power plant indirectly allows after-the-fact restoration and it should be 

prohibited since restoration is not allowed under 316(b) and the biological impacts of intakes do 

not differ based on whether the intake is associated with a power plant or manufacturing facility. 

The commenter refers to information in its comment letter that indicates that the desalinization 

plant is permitted to withdraw more seawater (304 mgd) than the AIF of the power plant. 

The language of the comment seems to indicate that in one example (Carlsbad CA) the 

desalinization plant withdraws water and provides water to a power plant, although this is 

somewhat unclear. A second example (Huntington Beach CA) follows EPA’s general 

understanding that typically water that is reused goes from a power plant to a desalinization plant 

to allow the desalinization process to benefit from the heated water. A basic flow diagram of the 

Carlsbad facilities indicates flow (100 mgd) from the power plant to the desalinization plant 

(http://carlsbaddesal.com/desalination-plant). This also indicates a flow of 600 mgd into the 

power plant. Also see, 

http://www.waterboards.ca.gov/sandiego/board_decisions/adopted_orders/2006/R9-2006­

0065_May_2010.pdf 

Today’s final rule promotes several forms of water reuse for the reasons discussed in the 

preamble. EPA does not agree that the provisions in § 125.91(c) and § 125.92 create a loophole 

that defeat the objectives of the rule since overall the amount of water reuse is limited relative to 

the amount of cooling water flow. Such reuse avoids new water withdrawals and therefore 

reduces the associated AEI. EPA disagrees this is restoration, as the water withdrawn for cooling 

purposes results in an actual reduction in AEI, and does not represent a mitigation effort. Based 

on the flow diagram referenced above, the Carlsbad power plant has 500 mgd of flow that is not 

reused by the desalinization plant and, thus is likely to remain subject to this rule. It is important 

to recognize that a desalinization plant that withdraws water is not subject to section 316(b), 

which focuses on cooling water intake structures. Thus, in the case of a stand-alone 

desalinization plant that facility would not be subject to water intake controls under this rule 

despite any AEI it may pose. Under today’s rule the power plant could reuse the water from a 

desalinization plant, and in doing such would not be causing additional AEI. 

Essay 11 27 
Essay 12: New Data Used In Developing the Rule

EPA received numerous comments and data on specific aspects of EPA’s analyses. These 

comments are addressed in other essays. This essay addresses comments received that provided 

highly specific corrections to data or documents provided in EPA’s record, such as corrections to 

EPA’s interpretation of state 316(b) policies and revised information on information collected 

during EPA’s site visits or by the industry questionnaire, that are not addressed elsewhere. EPA 

also notes that it received data submitted by various stakeholders throughout the rulemaking 

process; refer to the docket for the final rule. 

EPA appreciates the commenters’ submittals and has either incorporated the revisions into the 

final rule or has considered the materials in its analyses for the final rule. More specific 

responses to some comments are provided below. 

EPA appreciates the supplemental information provided regarding NJDEP’s permitting program 

and NYSDEC’s BTA policy. This information was not included in the preamble to the final rule, 

but has been corrected (as needed) in the support documents. 

EPA also appreciates the information provided regarding specific facilities. Each of the 

comments has been addressed, as described below. 

	 Westchester RESCO’s wedgewire screens: As the commenter noted, the TDD states the 

incorrect mesh size, but EPA’s site visit report (DCN 10-6517) is correct. The error has 

been corrected in the final TDD. EPA has generally considered any mesh size 2.0 mm or 

smaller to be considered fine mesh, so the correction does not appreciably change EPA’s 

characterization of this facility. 

	 LADWP’s revisions to the site visit reports: EPA appreciates the commenter’s additional 

revisions to the reports. Revised versions of these reports will be posted to the docket for 

the final rule. 

	 Technical information for the AES facilities: EPA notes that, in developing the 

engineering costs and determining a compliance response for model facilities, the data 

used were derived directly from the industry questionnaires, using information provided 

by the facility and reflective of operations at that time. However, two of the facilities 

mentioned by the commenter (Harding Street and Eagle Valley) completed a short 

technical questionnaire and any corrections to the facility data would not affect the costs 

for the final rule, as that data was not used in estimating compliance costs. (Please see the 

TDD for more information on how EPA used data from the detailed technical 

questionnaires to develop costs for model facilities.) For the third facility (Petersburg), 

EPA reviewed the industry questionnaire and confirmed that the survey marked the 

cooling system as “once-through only,” although it appears that a checkbox for “oncethrough with non-recirculating towers” was whited out. A review of the facility’s flow 

diagram confirms that Units 3 and 4 appear to use cooling towers, but also indicates that 

the makeup water withdrawals for those units comes from the discharge canal for the 

once-through units; as a result, EPA has updated its characterization of the facility from a 

Essay 12 28 
once-through cooling system to a combination cooling system. However, there is no 

resulting change in the estimation of compliance costs for this facility, as the number of 

intakes (one) and the volume of water withdrawn from the surface water is unaffected. 

Lastly, the actual intake flow (AIF) used for Petersburg was also taken from the 

questionnaire. This data was for the years 1998-2000 and varies by only 23.5 million 

gallons per day (approximately 7 percent of the AIF), which is not a sufficient difference 

to appreciably affect EPA’s estimates of the compliance costs. 

Essay 12 29 
Essay	 	 	 13: Possible Differences	 	 between Generators	 	 and Manufacturers

Many manufacturing stakeholder commenters expressed concern that EPA failed to take into 

consideration many of the differences between power generators and manufacturers during the 

development of the proposed rule. 

Introduction

In the proposed rule and NODAs, as well as the TDD for the proposed rule, EPA provided 

descriptions of the power generation industry and sectors of the manufacturing industry and how 

the compliance requirements, technologies, and costs apply to each. This essay addresses public 

comments regarding the description of the industry, the differences between power generators 

and manufacturers, and the application of compliance requirements, technologies and 

compliance cost assumptions. In particular, many manufacturing industry commenters were 

concerned that EPA relied upon data from the power industry and simply transferred many of the 

compliance and costs assumptions originally applied to generating facilities in the nowwithdrawn Phase II rule to manufacturing facilities without consideration of the differences 

between these industries. The main thrust of the arguments is that EPA must allow for sufficient 

flexibility in application of the final existing facility rule to account for differences in operation 

and water use between power industry and manufacturers and between different manufacturing 

sectors. Commenters maintain that simply stating a water intake is a water intake is not 

sufficient. 

EPA has considered the differences between generators and manufacturers and has addressed 

these differences by (1) using a model facility approach in developing the compliance costs, and; 

(2) by allowing facilities the choice of complying with the impingement mortality BTA standard 

at the facility level or by individual intakes, and; (3) by providing compliance flexibility by 

identifying several alternatives that have each been demonstrated to achieve or exceed the 

impingement mortality BTA standard. Further, for entrainment, the final rule establishes a BTA 

standard for entrainment that requires the determination of required entrainment reduction 

measures in a structured site-specific permitting proceeding. EPA disagrees that there are 

numerous significant differences between power plants and manufacturing facilities; see TDD 

for a profile of cooling systems, types of intake structures, and technologies in place. EPA has 

determined there are not significant differences between generators and manufacturers with 

respect to the design and functionality of cooling water intakes. When manufacturers withdraw 

cooling water for the purposes of power generation, there are no significant differences. Where 

cooling water is withdrawn by manufacturers for process cooling, some minor differences may 

be observed and are generally related to factors such as the intake water volume, changes in 

volume requirements over time, and subsequent (i.e., “downstream” of the intake structure) uses 

and are not related to factors that affect the ability to comply with the final rule requirements. 

EPA considered and evaluated subcategorization based on industry type and found that 

manufacturers use essentially the same intake technologies and cooling system types as electric 

generators and concluded that there are no data suggesting that manufacturers should be 

addressed separately on the basis of intake or cooling system technologies or availability. In site 

visits and through data collection, EPA found manufacturers more often withdraw water for nonEssay 13 30 
contact cooling water purposes (e.g., contact cooling water or process water) from the same 

intake structure. Since contact cooling and process water use may not be amenable to flow 

reduction through a technology such as closed-cycle cooling, entrainment requirements for flow 

reduction can only apply to non-contact cooling water; the final rule does not apply to contact 

cooling or process water withdrawals. See TDD Chapters 4 and 5 for additional discussion of 

differences and similarities between generators and manufacturers. 

EPA has provided sufficient flexibility and site-specific considerations within the compliance 

options available in the final rule to accommodate any minor differences between generators and 

manufacturers and between manufacturing facilities in different sectors. In fact, many 

manufacturers may have more compliance strategies available to them than power generators 

because they have the ability to reduce cooling water withdrawals by reusing cooling water as 

process water; generators typically have smaller process water requirements and would therefore 

not be able to achieve a significant reduction in withdrawals through water reuse. With respect to 

entrainment, the entrainment requirements will be established on a site-specific basis, allowing 

the Director to take into consideration the sort of facility and site-specific circumstances and 

differences cited by the comments. 

Background/History

Under the 316(b) Phase I New Facilities Rule, both new electric generating facilities and new 

manufacturing facilities with a design intake flow greater than 2 mgd and cooling water 

comprising greater than 25 percent are required to comply with the rule requirements and are 

regulated in a similar manner. In response to the remand of the Phase II and Phase III Rules, 

EPA revisited the regulations for existing facilities and decided to regulate both large flow and 

small flow electric generating facilities and all manufacturing facilities under this single Existing 

Facility Rule. See Section II of the final preamble for a more detailed discussion. Throughout the 

regulatory effort the primary difference between electric generating and manufacturing facilities 

with regard to cooling water intakes and impingement mortality and entrainment mortality 

observed by EPA is the different distribution of intakes by size. 

Analysis of Information for the Existing Facilities Rule

Some commenters expressed concern that EPA had visited many power generating facilities but 

not many manufacturing facilities and that it was unclear how many manufacturing facilities 

EPA had visited. EPA disagrees that it did not visit many manufacturing facilities. During 2009 

and 2010, EPA visited eight manufacturing facilities in order to better understand the cooling 

water intake structure (CWIS) technologies in use at manufacturing facilities, including the sitespecific characteristics of each facility and how these may affect the selection and performance 

of CWIS technologies. EPA also visited these facilities to better understand cooling water use 

and specific issues or technologies that can affect 316(b) compliance. The different types of 

industrial facilities visited included petroleum refining, steel manufacturing, chemical 

manufacturing, and food processing. EPA also collected additional data for pulp and paper 

manufacturing and aircraft engine manufacturing during meetings with facility representatives at 

EPA Headquarters. These site visits and meetings provided EPA with additional knowledge of 

any potential differences between power generating and manufacturing facilities, the differences 

between different types of manufacturing facilities, the unique circumstances relevant to each 

type of manufacturing facility, and how each factor could play a role in determining BTA. As a 

Essay 13 31 
                                                            

 

 

 

result of this effort, EPA gained a thorough understanding of the differences between how water 

is used at power generating and different types of manufacturing facilities and also confirmed 

that the intakes themselves and the technologies used did not differ significantly in design, 

operation, or function. EPA considered this information during the development of the final rule. 

For more information regarding the site visits conducted and information obtained see TDD 

Chapter 2. 

EPA’s data shows that many manufacturers use cooling water exclusively for power generation, 

and in such cases generators and manufacturers are virtually identical. In other cases, power 

generating and manufacturing facilities may use water differently (e.g., manufacturing facilities 

tend to use more process water and contact cooling water) and may have different operational 

considerations. However, all cooling water intakes serve a similar function and EPA found that 

the intake designs and technologies used at electric generating facilities were also found to be 

used at manufacturing facilities and vice versa. For example, three fourths of both generators and 

manufacturers use a single cooling water system (TDD 4-13). EPA further found that relative 

intake flows for generators and manufacturers are similar (59 percent and 54 percent of DIF 

withdrawn, respectively) (TDD 4-4). See TDD Chapter 4.0 for further examples and detailed 

analysis. The differences in water use do not impact the availability of certain types of controls 

that serve as the basis for the impingement mortality controls, mortality reduction technologies 

or their efficacy. For example, screening technologies are used by over 1000 generators and 

manufacturers alike, see TDD 4-19. The small differences in water use may impact the 

availability of certain flow reduction operational measures and technologies, such as closedcycle cooling5

. According to EPA’s survey, the most pronounced difference EPA observed 

between power generating and manufacturing facilities is that manufacturing plants were less 

likely to have any technologies to reduce impingement and entrainment. The second observation 

EPA made regarding intake characteristics was that a larger proportion of manufacturing 

facilities had smaller design intake flow volumes and were more likely to have a lower intake 

velocity (TDD 4-17, see below for more discussion). However, not all manufacturing facility 

intakes have lower flows, as EPA has estimated that the average manufacturing facility design 

intake flow is still more than 94 mgd (see TDD Exhibit 4-5). Just like power plants, there is a 

wide range of intake flows observed at manufacturing facilities. Manufacturing facility intakes 

also tended to have lower through-screen velocities, fewer systems with fish returns and 

employed more passive screen technologies (see TDD Exhibits 4-17 and 4-19). EPA notes that 

controls on smaller intakes will tend to cost less and may give the facility greater opportunities to 

use alternative compliance technologies6

. Intakes with lower screen velocities may be more 

capable of meeting the low velocity IM compliance alternative. Passive screens however, may be 

more costly to upgrade to traveling screens since there may be significant engineering necessary 

to convert from passive screens to traveling screens. EPA included these considerations in the 

development of the compliance costs estimates (see TDD Chapter 8). 

5

 For example, process and contact cooling water generally are not amenable to flow reduction through closed-cycle 

cooling. However, higher proportions of process and contact cooling water at manufacturing facilities do provide 

greater opportunity for employment of water re-use flow reduction strategies. See also additional discussion in the 

TDD, for example at 5.3.2 and 8.3.1.

6

 For example, the availability of low velocity intake technology such as T- screens, expanded intakes, additional 

offshore intakes, and wedgewire screens may be greater since the footprint and water depth requirements of smaller 

intakes would allow placement near or adjacent to shore where additional screens or intakes would be easier to 

install and less likely to interfere with navigation. 

Essay 13 32 
Several commenters pointed out that EPA has ignored the differences between the power 

industry and manufacturing industries that justified EPA’s different compliance approaches in 

Phases II and Phase III. They stated that EPA has provided no new justification for altering the 

previous approach and request that manufacturers should continue to be regulated on a sitespecific basis as in Phase III suggesting that EPA should drop manufacturing facilities from the 

scope of the rule. They also note that total industrial water use on a percentage basis is small 

enough not to have an overall adverse environmental impact in the U.S. They also note that the 

costs of the impingement mortality controls and entrainment requirements are wholly 

disproportionate to the benefits. EPA disagrees with commenter assertions that applying the 

existing facility rule BTA requirements to both manufacturing and generating facilities is not 

justified. EPA did, in fact, consider a compliance option at proposal (Option 4) that was modeled 

on such an approach that would have established site-specific BTA requirements for the majority 

of manufacturing facilities which have a design intake flow (DIF) of less than 50 mgd. The two 

main differences between Option 4 and today’s final regulatory option for existing facilities are 

that today’s’ rule requires facilities subject to this rule to meet IM performance standards and 

that the site-specific entrainment determination be performed in a structured way with 

consideration of appropriate information and specific factors. With respect to the requirement to 

meet the IM performance standard, EPA based the BTA IM standard on the performance of 

traveling screens for all facilities subject to today’s rule (i.e., in scope generators and 

manufacturers). EPA concluded that this technology is effective, widely available, feasible, and 

does not lead to unacceptable non-water quality impacts. Furthermore, the inclusion of seven IM 

compliance alternatives provides a high degree of flexibility. For more discussion, see Essay 19. 

With respect to the structured site-specific entrainment determination, EPA similarly finds that 

approach is flexible enough to apply to all facilities subject to today’s rule. 

EPA disagrees that total industrial water use on a percentage basis is small enough not to have an 

overall adverse environmental impact in the U.S., as EPA has already identified numerous case 

studies where a single facility was causing an adverse environmental impact. In addition, at least 

14 percent of manufacturers below 50 mgd withdraw more than 5 percent of the mean annual 

flow (MAF) river; in Phase II, the 5 percent MAF criteria was used as one indicator of cooling 

water intake structures having an adverse environmental impact. Even at 20 mgd, there are 17 

facilities that withdraw more than 5 percent MAF, and another 11 which withdraw from small 

unnamed or unknown source waters. Thus one fourth of the 116 facilities under 20 mgd exceed 5 

percent MAF. The EPA concludes that such flows are not small flows or low flows. Further, 

cumulative impacts of facilities with DIF below 50 mgd are significant in most of the U.S. At 

least 54 percent of withdrawals by just those facilities with DIF below 50 mgd are cumulative 

withdrawals, i.e., there are withdrawals by more than one facility on the same river segment. See 

TDD Chapter 4 GIS overlays of co-located facility intakes, Essay 14, and TDD Chapter 5 for 

more information. 

Commenters have asserted that EPA has relied mostly upon data and analyses for power plants 

and have simply applied the results to manufacturers without considering the differences. They 

assert that EPA has established separate effluent guidelines for the many different industries 

included in this rule as well as different electricity-generating power plants and that this rule 

essentially lumps them all into one without consideration of the differences. EPA agrees that 

many of the intake technology applications and cost modules used for the installation and 

operation and maintenance of the technologies upon which the impingement mortality 

Essay 13 33 
requirements were based in the final rule were adapted from those developed for the Phase II 

Rule. EPA found that manufacturers use essentially the same intake technologies and cooling 

system types as electric generators (see TDD Chapters 4 and 5) and commenters have not 

presented any specific data explaining why the technologies used at generating facility intakes 

cannot be used at manufacturing facility intakes. The primary reason that the same technologies 

are used at both generating and manufacturing facilities is that at both types of facilities the 

intakes serve the same function and purpose. In all cases, the primary function and purpose is to 

make available a continuous supply of water that is relatively free of debris that may interfere 

with downstream uses of the water. EPA agrees that there are small differences between power 

generating intakes and manufacturing intakes with regard to the frequency and distribution of 

technologies used, but no single intake technology is unique to one or the other. EPA recognizes 

that the availability, efficacy, and relative cost of each technology will vary from site to site and 

accounted for this variation by providing facilities with multiple alternatives for complying with 

the impingement mortality BTA standard that allows a facility to choose from a wide variety and 

mix of technologies and operational measures (see Section VI of the preamble). EPA also 

accounted for these differences in the compliance cost analysis. Compliance technologies are 

selected for the model facilities based on site-specific parameters (see TDD Chapter 8). 

Differences in the distribution and availability of technologies prompted EPA to revise the cost 

methodology to reflect these differences. EPA found that manufacturing intakes tended to use 

passive technology more frequently and traveling screens less frequently. Originally, in the 

proposed compliance cost estimates, EPA assumed that even facilities without traveling screens 

could easily upgrade to traveling screens. EPA realized that intakes that do not currently use 

traveling screens may not be able to simply replace existing screens with traveling screens and 

revised the technology selection methodology for the costs estimates such that a more costly 

technology such as new larger intake or wedgewire screens would be selected at any intake that 

did not have existing traveling screens. See Essay 21 and TDD section 8.2.2.1 for a more 

detailed discussion. With respect to the comment that EPA extrapolated the environmental 

impacts of larger flow power plants to manufacturing facilities, EPA disagrees. EPA has more 

than 40 biological studies from facilities below 50 mgd in the record. 

Several commenters expressed concern that EPA did not consider that manufacturers cannot 

simply stop production or curtail operations the way power generating facilities that operate on 

the “grid” can. EPA agrees that the ability to avoid interruptions in plant operation due to 

construction downtime can be site-specific. In most instances, EPA found that plant operators 

would develop specific solutions in the event any downtime is necessary. For example, some 

manufacturers can coordinate installation downtime with other scheduled outages, can purchase 

or obtain power and/or steam from other nearby sources at a cost far less than stopping 

production, and can stockpile intermediate products to allow a phased approach to installing 

control technologies at individual unit operations. During site visits and in discussions with plant 

operators, EPA confirmed that for most manufacturing plants, a solution can be engineered that 

would avoid any incremental downtime at most sites. Further, where necessary, such 

interruptions can be taken into account by the permit writer in its site-specific consideration of 

entrainment controls. In terms of compliance with the IM requirements, EPA expects this 

downtime, if any, is addressed by the timelines contemplated by the rule. During the period when 

the facility is collecting and submitting materials under this timeline, the final rule at § 

122.21(r)(8) ensures both the owner or operator and the Director will have an understanding of 

Essay 13 34 
future operational schedules and can coordinate the installation of technologies with planned 

shutdown activities. Also see Essay 35. 

Commenters have noted that total manufacturing facility withdrawals are only about 10 percent 

of the total for the electric generating industry. EPA agrees with this estimate but has determined 

that this factor does not warrant separate treatment with regard to regulating impingement and 

entrainment. There are large and small intakes within both groups and EPA has concluded that 

size alone does not always correlate to relative impacts. As already discussed above a 

manufacturer could be located on smaller water where even a smaller amount of intake will have 

some environmental impact. Commenters also neglected to acknowledge cumulative impacts 

from multiple users of a given source waterbody. 

Commenters noted that manufacturing facilities which compete in a global economy cannot pass 

costs on to consumers as readily as power generators can. EPA acknowledges these concerns and 

did treat manufacturing facilities differently in the economic analyses. In the economic analysis 

EPA assumed no cost pass through for all manufacturing facilities (see Essay 47). Even under 

such conservative assumptions, the EPA found that only one facility experienced a cost to 

revenue ratio greater than 1 percent. For generating facilities, EPA took different approaches 

concerning cost pass through depending on the analysis being performed. See the EA for a more 

detailed description. 

EPA also addressed the differences between power generating and manufacturing facilities in 

assessing the impact of social costs in the economic analysis. See the EA for a more detailed 

discussion of social costs. 

A commenter noted that flow reduction may create problems with concentration based 

compliance limits for mixed cooling and process water discharges. EPA agrees that there may be 

a limited number of instances where such a problem may be encountered but notes that NPDES 

permit limits tend to use mass-based limits in order to avoid discouraging flow reduction or 

encouraging dilution. EPA notes that facilities have seven IM compliance alternatives and that 

flow reduction is not required by any facility, unless it elects to comply via that approach. The 

Director has been given wide discretion with regard to entrainment reduction requirements and 

EPA would expect Director’s to include consideration of this issue in the determination of flow 

reduction requirements. 

A commenter noted that the steam electric industry has significant experience with CWIS issues, 

including a wealth of site-specific data, while the other segments typically do not. EPA agrees 

that there may be significant differences in the amount of technical knowledge and biological 

data collected between these industries, especially between power generators covered by the 

Phase II Rule and manufacturers. Recognizing that some facilities may need additional time to 

conduct technology assessments and collect biological data, the rule included several provisions 

that provide flexibility for the permit application requirements. See Section VIII for more details. 

On the other hand, EPA’s compliance costs for manufacturers may be overstated since the 

industries will be able to benefit from cost effective solutions already developed or under 

development by power generators. 

Essay 13 35 
                                                            

One commenter noted that the proposal preamble at page 22190 incorrectly stated that the 

Effluent Guidelines for the Steelmaking subsector of the Iron and Steel ELG require no 

discharge of process pollutants. They point out that only EAF utilizing semi-wet gas cooling 

systems are restricted to no discharge and suggest that EPA perform additional evaluation of the 

steel industry, and other non-electrical generating industries to better understand water use. Since 

proposal as described above, EPA visited numerous manufacturing facilities of different types 

including two steel making facilities. EPA has revised the preamble discussion regarding 

steelmaking regulations and water use and considered the information obtained from the site 

visits during the development of the final rule. 

One manufacturing commenter stated that they spent over $250,000 (not including I&E or 

thermal studies) amassing information requested as part their NPDES permit renewal and despite 

the data submitted the permitting authority compared their small generating unit to a large 

generating plant in the region and reached incorrect conclusions regarding the feasibility of 

closed-cycle cooling as an entrainment control option. EPA notes that the commenter is 

describing a site-specific determination of entrainment requirements conducted by the permitting 

authority and that today’s final rule provides a structured approach that will allow a 

manufacturing facility to provide information specific to it and for the Director, as appropriate, to 

consider the information. A commenter stated that EPA admits that it does not fully understand 

key issues associated with manufacturing sites citing EPA’s statement that “EPA has observed 

significant water reuse at manufacturing facilities, but has not developed national level data for 

such reuse due to the range of different manufacturing sectors and the significant variability in 

manufacturing processes (during site visits, it was observed that complex facilities have found it 

difficult to assess their specific water reuse).” EPA disagrees that failure to develop national 

level data for water reuse practices means that EPA is unable to make policy decisions about the 

appropriate way to control cooling water intakes at manufacturing facilities. As discussed in the 

proposal 76 FR 22200 and the final rule preamble section VI, EPA has sufficient information in 

the record to demonstrate the widespread use of these technologies. For example, 313 facilities 

have intake velocity below 0.5 fps; 1054 facilities already employ some form of traveling screen 

plus 168 of these facilities already have a fish handling and return system; 235 use passive screen 

technologies; 80 facilities already have behavioral deterrent systems; 400 facilities already have 

closed-cycle cooling. See TDD Chapter 4 for more information. For specific information 

regarding achievability of the IM performance standard using modified traveling screens, see the 

TDD Chapter 11 and the June 2012 NODA. 

EPA notes that the degree of water reuse can be relevant in determining whether a facility meets 

the 25 percent cooling water criterion for facilities that fall within scope of the rule7 and in 

assessing flow reduction in determining entrainment reductions. Under the final rule these 

determinations are performed on a site-specific basis and therefore the specific situation at each 

facility will be assessed independently at that time. The degree and nature of water reuse 

downstream of the cooling water intake generally does not provide any less opportunity for a 

manufacturing facility to comply with the impingement mortality BTA requirements than a 

generating facility with similar intake characteristics. In fact, since manufacturing facilities tend 

to have greater opportunities to employ water reuse than generating facilities, they also tend to 

have greater opportunity to utilize compliance strategies that rely upon flow reduction which 

7

 Cooling water that is reused for another purpose is excluded from the definition of cooling water. 

Essay 13 36 
                                                            

may assist in complying with the IM low velocity compliance alternative or provide credit for 

reduction under the system of technologies compliance alternative. 

A commenter submitted the report, “Freshwater Use by U.S. Power Plants: Electricity’s Thirst 

for a Precious Resource.” EPA welcomes this data and assessment of current and future water 

use by power generators in the United States. The report does suggest that water stress related to 

water consumption could be an issue in the future at many locations but the report does not 

comment on the rule and EPA finds nothing in this report that is in disagreement with EPA’s 

general assessment or regulatory approach. With respect to the site-specific evaluation of 

controls for entrainment, the rule provides for consideration of consumption issues. (See Essays 

17A and 19, as well as DCN 12-6673.) 

Where difference may exist, EPA has taken into consideration the differences between 

generators and manufacturers and differences between manufacturing sectors by structuring the 

final rule to account for the wide variety of site-specific technology designs by allowing for IM 

compliance flexibility enabling each facility (each intake if necessary) to tailor the compliance 

technologies to specific site conditions. IM compliance alternatives include several compliant 

technologies (closed-cycle, low intake screen velocity, existing offshore velocity caps), 

streamlined monitoring for modified traveling screens, and employment of a system of 

technologies in which the aggregate combined performance are demonstrated to be equivalent to 

the BTA technology. Facilities may also choose to comply with the IM numerical limit via 

biological monitoring. See Essay 16 and Section VI of the preamble for more details. Also, 

manufacturing facilities that are able to increase cooling water reuse such that more than 75 

percent of the water withdrawn is not used for cooling purposes8

, may no longer fall within the 

scope of the final regulation and would not be subject to the requirement of the final rule. Those 

manufacturing facilities that employ cooling water reuse may take credit for this reuse through 

the “system of technology” compliance alternative. 

In developing the compliance cost estimates EPA used the model facility approach to address the 

differences between facility intakes. EPA did address the differences in costing approach for 

CCRS, downtime, default values, and new units. See Essay 21 for a discussion of manufacturing 

facility closed-cycle costs and Essay 35 for a discussion of manufacturing construction 

downtime. 

In conclusion, the final rule has carefully included consideration of the differences between 

power generation facilities, manufacturing facilities and the differences within the manufacturing 

sector as well with regard to water use, intake design and technologies, operational 

considerations, economic considerations and ability to comply with the rule. By providing 

flexibility with regard to compliance alternative, EPA has enabled facilities with different 

facility-specific conditions to choose a compliance option that best suits the unique conditions at 

each facility. 

8

 Note that cooling water that is reused for non-cooling purposes does not meet the definition of cooling water. 

Essay 13 37 
Essay	 	 	 	 14: Scope and Applicability

Introduction

The scope, applicability, and basis for the final rule are largely unchanged from that of the 

proposed rule. In response to comments, the final rule does, however, include some minor 

changes to regulatory definitions that clarify the scope of this rule. 

As discussed in the preamble to the final rule and provided in Subpart J at 40 CFR 125.91, this 

rule applies to existing facilities (as defined in 40 CFR 125.92(k)) that are point sources under 

the Clean Water Act, use or propose to use one or more cooling water intake structures (defined 

at 40 CFR 125.92(f)) with a cumulative design intake flow (DIF) of greater than 2 million 

gallons per day (mgd), that withdraw water from waters of the United States, and use twenty-five 

percent or more of the water withdrawn exclusively for cooling purposes on an actual intake 

flow (AIF) basis. The rule defines DIF and AIF at 40 CFR 125.92. 

In general, an “existing facility” means any facility that commenced construction on or before 

January 17, 2002, (or July 17, 2006 for an existing offshore oil and gas extraction facility) and 

any modification of, or any addition of a unit at such a facility. Today’s final action does not 

affect the scope and applicability of Subpart N (new offshore oil and gas extraction facilities) or 

Subpart I (new facilities). Subpart J applies to all existing facilities meeting the definition in this 

subpart. The applicability provision at 40 CFR 125.91(d) makes it clear that Subpart J does not 

apply to existing facilities that are seafood processing facilities, offshore liquified natural gas 

terminals, and offshore oil and gas extraction facilities. The final rule also defines new units at 

existing facilities. See Essay 20 for response to comments on the technology requirements for 

new units. 

See the preamble to the final rule for a detailed discussion of the scope of this rule, including the 

following subject areas: general applicability, existing facility, cooling water, cooling water 

intake structures (CWIS), point source discharger, withdrawals from waters of the United States, 

use of independent suppliers, intake flow thresholds, existing offshore oil and gas facilities, 

existing offshore seafood processing facilities, liquefied natural gas (LNG) terminals, and new 

units. 

General Applicability

Clarify Applicability /Exclusions

Commenters requested that, in the final rule, EPA clarify certain basic aspects of the 

applicability of the rule. Some commenters requested that EPA clarify the applicability 

provisions of the rule, specifically whether the rule is limited to steam electric and manufacturing 

facilities or also includes facilities such as hospitals and schools. Some asked how facilities with 

multiple units with different types of cooling are addressed (including with one or multiple 

CWISs). Some commenters want EPA to clarify that the rule applies only to cooling water intake 

structures that are actually used to withdraw cooling water. Commenters also suggested that EPA 

clearly state that portions of a CWIS that are downstream of a screen with through screen 

Essay 14 38 
velocity less than 0.5 ft/sec are not subject to the rule. Some asked EPA to clarify whether 

monitoring provisions (§ 125.96(a)(1)) authorize multiple compliance points or whether the 

NPDES permitting authority has discretion in establishing monitoring points. Some commenters 

also requested that EPA define the terms “unit,” “operating unit,” “contact,” “non-contact,” and 

“process water.” 

EPA has described the applicability of the existing facility rule in the scope section of the 

preamble to the final rule. The regulation at § 125.91(d) clearly specifies which existing facilities 

are not subject to Subpart J. This rule applies to any facility that meets the applicability criteria 

for the rule at § 125.91(a) and therefore it is not limited to steam electric and manufacturing 

facilities. 

In cases where a facility has multiple cooling water intake structures, under 40 CFR 122.21(r)(6) 

of the permit application, the owner or operator must identify the chosen impingement 

compliance method for the entire facility under 40 CFR 125.94(c) or alternatively, the permit 

application must identify the chosen compliance method under for each cooling water intake 

structure at the facility. Each intake used for cooling water withdrawals is subject to section 

316(b). The rule includes several alternatives for meeting impingement mortality requirements. 

In the case of the impingement mortality performance standard alternative, the standard may be 

implemented on a facility or intake basis. Thus the rule provides flexibility to an in-scope facility 

to select an impingement compliance approach that accounts for multiple units or multiple 

intakes. 

The rule does not require the all facilities to identify entrainment controls in the permit 

application because the BTA for entrainment will be determined by the Director on a case-bycase basis. The final rule establishes a framework for facilities to submit studies to the Director 

to inform the determination of BTA for entrainment. In the case of facilities with AIF greater 

than 125 mgd, however, such facilities must provide relevant information on candidate 

entrainment control technologies and information on entrainment measures already in place with 

at their facilities. Such information is required under § 122.21(r)(9)-(12). For facilities below this 

threshold, the Director has the discretion to request whatever information is necessary to make 

the entrainment determination. 

All facilities that have a cooling water intake structure are subject to section 316(b) of the CWA. 

Existing facilities that are not subject to the national BTA standards at 40 CFR 125.94 must meet 

requirements under section 316(b) that are established by the NPDES permitting Director on a 

case-by-case, best professional judgment basis as the final rule at 40 CFR 125.90 makes clear. 

The final rule establishes national BTA standards for existing facilities that use one or more 

CWISs to withdraw greater than 2 mgd of cooling water and meet other criteria. As discussed in 

more detail below, EPA established this threshold for applicability of the final rule BTA based 

on data showing a 2 mgd threshold addresses the vast majority of cooling water flows (i.e., 99.7 

percent). The record shows that the BTA standard for impingement mortality controls is 

achievable for all in-scope facilities and controls to meet the standard are widely available; see 

the preamble for more details. Certain aspects of the rule are addressed to facilities with the 

largest intake structures and largest cooling water intake flows. For example, there are more 

detailed permit application requirement for facilities above 125 mgd. The additional data 

required for these permits is necessary to assist the Director in the site-specific decision-making 

Essay 14 39 
required by the BTA standard for entrainment to develop the specific entrainment requirements 

applicable to such facilities. Facilities withdrawing fewer than 125 mgd are not required to 

submit this information unless it is requested by the Director. In the case of these smaller flow 

facilities, the EPA concluded that the Director would not necessarily need this additional 

information in order to establish BTA entrainment requirements. 

With regard to an intake that does not withdraw any cooling water but is at an in-scope facility, 

EPA agrees such an intake is not subject to requirements under this rule as long as it does not 

withdraw cooling water. For example, an intake that does not withdraw water for cooling, such 

as an auxiliary intake used exclusively for fire suppression, is not subject to section 316(b). 

Some commenters appear to be confused about the difference between section 316(b) 

requirements and the uniform requirements established by this rule. Section 316(b) of the CWA 

requires that all intakes at existing facilities that withdraw water for cooling are subject to section 

316(b) requirements. Only those facilities meeting the applicability criteria at 40 CFR 125.91(a), 

however, are subject to the standards established in the final rule. All other existing facilities that 

do not meet the applicability criteria at § 125.91(a) will continue to be subject to section 316(b) 

requirements developed by the NPDES permitting authority on a case-by-case, BPJ basis. 

EPA disagrees that a facility with low intake velocity should be automatically exempted from the 

rule. While low intake velocity is a compliance alternative for the IM performance standard, 

EPA’s record shows that low intake velocity has no significant effect on entrainment. In 

particular, eggs and early life stages of larvae have no avoidance response or mobility, therefore 

a low velocity is not protective of these organisms. The Director must consider whether 

additional controls for entrainment still need to be developed at a facility that already meets the 

IM performance standards when the Director is making the site-specific determination of BTA 

entrainment requirements required by this rule. 

Under the final rule, portions of a CWIS that are downstream of a screen with through-screen 

velocity less than 0.5 ft/sec would be able to comply with the IM performance standard via the 

low velocity compliance alternative. EPA has removed the additional provisions for entrapment 

from the final rule. However, where a facility elects to comply with the IM BTA standard via the 

IM performance standard compliance alternative, any entrapped organisms must still be counted 

as mortality; see 40 CFR 122.94(6)(i)(F). Similarly, facilities that elect to comply with one of the 

IM compliance alternatives that requires an optimization study must consider entrapped 

organisms as mortality. The rule provides for monitoring and reporting to make sure that this 

requirement is met and to provide transparency to the affected communities that the facility is 

meeting this requirement. Facilities should also not be exempted because the Director may 

determine that further requirements beyond velocity controls for IM (or entrainment controls) are 

necessary for threatened and endangered (T&E) species, shellfish, or fragile species; see 40 CFR 

125.94(c)(8) and (9) and 40 CFR 125.98(f). These additional requirements may include controls 

for impingement, entrainment, or both. All facilities with cooling water intakes, even low intake 

velocity facilities, remain subject to all applicable portions of the rule and applicable NPDES 

permit provisions, including all requirements for compliance monitoring, data gathering, and 

submission of certain studies. 

Essay 14 40 
Some commenters raised questions concerning monitoring for multiple compliance points with 

the BTA impingement mortality standard. Compliance with certain of the alternatives for the 

impingement mortality standard (e.g., combination of technologies at 40 CFR 125.94(c)(6)) 

requires submission of a performance optimization study with a minimum of two years of 

biological data gathering/collection in order for the Director to determine whether the controls 

represent BTA impingement mortality control. The system of technologies may involve, for 

example, reductions in impingement due to intake location, flow reduction, or behavioral 

deterrents. The system may also include screens or other technologies. Therefore, the 

performance optimization study necessarily involves multiple monitoring points. The permit 

must then contain narrative requirements that ensure each technology is operated in an optimized 

manner, consistent with the demonstrated performance. Other impingement mortality 

compliance alternatives include the minimum monitoring provisions at 40 CFR 125.96. There 

may also be additional impingement mortality monitoring requirements established pursuant to 

40 CFR 125.96(a)(1). This provision authorizes the Director to require additional compliance 

monitoring requirements such as biological monitoring, intake velocity and flow measurements. 

EPA expects that such monitoring will correspond to application of the rule’s impingement 

mortality requirements and thus would depend on the configuration of the facility and 

compliance alternative adopted and could encompass multiple monitoring points. As with all 

NPDES permits, monitoring data are used to inform the Director and to assess compliance. 

Additional discussion of multiple compliance points may be found below in the Point of 

Compliance section of this comment response. 

EPA is defining key terms for the final rule in 40 CFR 125.92, revising these definitions from the 

proposal where changes provide clarity or are otherwise appropriate. EPA did not further define 

“new unit” by including a definition of the terms such as “unit” and “operating unit” because 

these terms are widely understood. Certain other terms are not defined specifically in this rule 

because already defined in EPA’s regulations. For example, the term “non-contact cooling 

water” is defined in 40 CFR 401.11. Similarly, the term “process wastewater” is defined 40 CFR 

122.2. There was no reason to define these terms differently for the purposes of cooling water 

intakes. EPA is confident that by reviewing existing definitions that are applicable to the NPDES 

program and the special definitions provided in the final rule, stakeholders can understand and 

apply the requirements of the rule. 

Commenters also suggested that EPA exempt certain facilities from the rule. Some commenters 

stated that EPA should exempt small and infrequently used (less than 30 days a year) intakes 

from the rule’s requirements. Some commenters recommended that EPA exempt utilities that 

generate less than 100 megawatts from the final rule’s requirements. Other commenters 

maintained that EPA should exempt from the rule once-through facilities that provide fresh water 

diversions to help rebuild wetlands and rebuild ecosystems in Louisiana (to create an incentive 

for such activities). 

EPA decided not to adopt the suggestion that the rule exempt facilities that operate infrequently 

for several reasons. First, some electric generating facilities functioning as peaking plants are 

still likely to affect aquatic organisms adversely. Many operate during biologically important 

periods of the year, e.g., spawning, early life stage or migration periods. Moreover, many 

peaking facilities continue to withdraw significant volumes of cooling water even when the 

facility is not producing power. In other cases, water is withdrawn to reduce startup times, avoid 

Essay 14 41 
pump cavitations, or to keep the cooling water intake system primed. Therefore facilities may 

operate their cooling water intake structures even when electricity or manufactured goods are not 

being produced. Other facilities may withdraw water for relatively short periods of time, but such 

withdrawals may coincide with spawning seasons or other biologically important periods. Such 

withdrawals may still pose an adverse environmental impact. Therefore EPA disagrees that 

infrequently operated facilities should be categorically exempted from compliance with the BTA 

impingement mortality and entrainment standards. However, the final rule does include 

provisions that may provide relief from impingement mortality controls in those instances where 

infrequently used facilities are not causing significant adverse environmental impact. The final 

rule provides flexibility for the Director to decide not to require impingement controls where 

rates of impingement are exceptionally low as to be de minimis. In the case of infrequently used 

facilities, the facility can take credit for reductions in cooling water withdrawals as part of their 

system of technologies; see the Implementation section of the preamble and the NODA at 77 FR 

34324 for examples. The rule does not exempt power facilities with lower power generation rates 

for the same reasons discussed above. In addition, a low power facility does not always mean 

low intake flows. A low power facility could, for example, generate steam in addition to electric 

power. The final rule does, however, include a provision for low capacity utilization power 

generation units that allows the Director to establish less stringent impingement mortality 

requirements in those instances where the facility can demonstrate no adverse environmental 

impacts. Further, the Director may factor into the site-specific determination of BTA for 

entrainment that a facility’s limited usage of that intake. The final rule does not exclude oncethrough facilities that divert water to rebuild wetlands since section 316(b) addresses the 

withdraw of cooling water, and such diverted water does not reduce the withdraw of cooling 

water. Also see Essay 19. 

Point of Compliance

Numerous commenters addressed the need for a clear point of compliance for the rule 

requirements. Some commenters stated that EPA should define CWIS to make the point of first 

withdrawal from a water of the United States the single point of compliance for 316(b), even 

where impoundments are part of the CWIS and are themselves waters of the United States. 

Comments to the contrary indicated that the point of intake from a water of the United States for 

makeup water provided to a cooling pond or reservoir should be the point of compliance. Some 

commenters stated that if a cooling pond is water of the United States, then withdrawal of water 

for a pond is merely a water transfer and that the point of compliance should be for water that 

goes from a pond to a facility. Commenters also suggested that EPA clarify one point of 

compliance per CWIS or risk multiple internal points of compliance with added costs not 

addressed by EPA. Some commenters observed that it is important to avoid multiple compliance 

points. Other comments suggested site-specific factors should be considered, but there should be 

a single point of compliance. Some commenters suggested that EPA allow flexibility to select an 

appropriate point of compliance. Commenters observed that it is important to clarify the 

applicability of the rule requirements (i.e., point of compliance) in specific situations, for 

example when an intake is used to withdraw water from a river and deposit it in an 

impoundment, holding or storage lake, basin, or cooling pond, or when an intake is used to 

withdraw water from an impoundment and provide that water to a cooling unit. Some suggested 

that a water supply intake that pumps water to a cooling pond/ reservoir/ lake should not be 

subject to the rule since the intake pump has no discharge to a water of the United States. Some 

Essay 14 42 
commenters asked that EPA clarify the point of compliance for the velocity requirements. These 

commenters observed that the point of compliance could be the mouth of the intake or the 

screen. Some asked for clarification of the point of compliance for intake tunnels and the use of a 

forebay. Finally, commenters asked whether the new unit provisions at 40 CFR 125.94(e) 

indicates multiple compliance points. 

As noted, the final rule establishes the BTA standards for impingement mortality and 

entrainment. What specific impingement mortality and entrainment controls will be required in 

the case of individual facilities as a result of the final rule will be determined in individual permit 

proceeding. How and where compliance with these requirements should be measured will 

necessarily depend on the nature of the particular controls required as a result of the permitting 

process. Thus, the point of compliance is a function of the BTA compliance alternative being 

implemented in a permit and the elements of the CWIS, possibly including associated 

constructed waterways, subject to BTA requirements or monitoring provisions. Further, in some 

cases it is necessary to allow for more than one point of compliance to accommodate the 

difference in control technologies that reduce mortality and the control technologies that reduce 

numbers of organisms impinged and entrained in the first place. In other cases, facilities have 

more than one intake structure, thus the final rule must be able to accommodate multiple points 

of compliance. EPA notes that the rule streamlines or eliminates biological compliance 

monitoring for many of the alternatives for IM. As discussed in the preamble, in most cases no 

biological compliance monitoring is required. EPA’s decision to adopt this approach is further 

supported by the large number of commenters pointing out the variations in intake structure 

locations, multiple appropriate points of compliance, and the specific situations that warrant a 

site-specific decision on the point of compliance. In any event, the EPA disagrees that multiple 

compliance points will result in costs not considered by the EPA. While the majority of facilities 

have single intake structures (67 percent of generators have a single intake structure and 76 

percent of manufacturers have a single intake structure; see TDD Chapter 4), EPA included 

compliance costs for every intake at a facility; in some cases EPA included costs for more than 5 

intakes at a single facility for compliance with the final rule. 

As an example, the Director may determine that, in the case of an existing CCRS using wet 

cooling towers, compliance should be measured at the point at which makeup water for the 

cooling towers is withdrawn. This point could be a water of the U.S., the point of withdrawal for 

an impoundment, or another entity providing treated wastewater to be reused as cooling water. 

EPA acknowledges that the point of compliance for facilities with an impoundment may also 

vary depending on the nature of the impoundment and whether the facility withdraws from a 

water of the United States. It is important to note that CCRS requirements focus on reuse, 

minimized makeup and blowdown, makeup to replace only blowdown, drift and evaporation, 

and performance criteria for fresh and salt water intakes. However, EPA also acknowledges that 

an intake structure may be used for more than just cooling purposes, and that more than one 

intake may be utilized. Each of these intake points would need to be accounted for. 

With respect to intake velocity, EPA disagrees with the comment that the mouth of the canal 

should be the sole compliance point. The final rule at 40 CFR 125.94(c)(2) and (3) makes it clear 

that the through-screen intake velocity is a point at which compliance would be measured. In a 

situation where a facility choosing to comply with the actual velocity requirement, the intake 

canal may have a velocity at the mouth of the canal that is less than 0.5 fps. However, the facility 

Essay 14 43 
still must meet the 0.5 fps standard at the screens. As discussed in the TDD, fish must be able to 

escape from impingement on the screen, forebay, or intake area, even though the velocity at the 

mouth of the canal is low enough to allow fish freedom of movement. The Director may 

determine it is appropriate to establish permit conditions that require velocity monitoring at both 

locations. 

For an existing offshore velocity cap, the cap location (relative to shoreline and the littoral zone) 

and its design must meet the definition in the rule and, as a result, the compliance is measured 

primarily at the velocity cap. This is likely the case regardless of any cooling water system 

downstream from the velocity cap (assuming the downstream system is not used to meet the rule 

requirements). For example, while an offshore velocity cap typically supplies water to a forebay 

or canal used for a reliable level cooling water supply, the primary point of compliance for the 

impingement mortality requirements of the rule is the offshore cap, even though traveling 

screens are in place in the forebay. 

As noted, an existing facility that intends to meet the impingement mortality requirements of the 

rule through installing and operating modified traveling screens must ensure that the screens and 

fish returns meet the definition at § 125.92. Compliance for this impingement mortality 

alternative requires operation of the facility in compliance with permit conditions that will ensure 

the modified traveling screens are operated so as to obtain the optimum performance that the 

Director determined is the best technology available for impingement reduction at the site. The 

primary compliance point for this requirement may include the traveling screens, but also 

includes elements of the fish return. Thus the Director may reasonably establish permit 

conditions that require visual monitoring at multiple points of compliance. Similarly, the systems 

of technologies alternative is expected to result in multiple points at which compliance must be 

measured. For example, a facility employing a particular technology that the Director has 

determined is BTA at the site for reducing impingement, such as a barrier net or an acoustic 

deterrent, may need to demonstrate that the performance of the technology is optimized 

consistent with the data reviewed by the Director. In the case of the Director’s approval of the 

use of variable speed drives or seasonal operation at a particular site as part of the BTA 

impingement mortality controls, the Director may require both biological data and volumetric 

flow measurements be taken at the intake structure, and may include further seasonal or 

otherwise intermittent monitoring requirements. Once the facility has demonstrated to the 

satisfaction of the Director that the system is BTA for that CWIS, EPA expects the Director 

would establish operational measures as permit conditions. 

Each facility will have to meet any applicable entrainment requirements, as well as other typical 

permit requirements (e.g., BMPs, monitoring, reporting, and recordkeeping). Compliance with 

entrainment requirements will depend on the specific requirements established (e.g., flow 

reduction, re-location of intake, etc.). A facility that chooses to demonstrate entrainment survival 

after passage through the facility would necessarily need to measure organism counts both before 

and after the intake structure. Similarly, other permit requirements may result in additional 

compliance measures and combinations of technology requirements may result in required 

measurement for compliance at many different points. 

If the new unit construction is associated with a new intake structure, it is likely that a single 

point of compliance will be established in the permit to measure performance commensurate 

Essay 14 44 
                                                            

 

with closed-cycle cooling. For new units complying under § 125.94(e)(2), or for new units using 

an existing intake structure, the use of multiple compliance points would be the same as 

discussed above. 

EPA has estimated costs for the rule including but not limited to costs for meeting BTA 

standards for IM, monitoring, recordkeeping and reporting, plus additional studies and 

monitoring for purposes of determining BTA for entrainment. While EPA acknowledges that 

some facilities will likely install additional technologies as a result of the framework that 

requires the Director to establish the BTA entrainment requirement for a facility based on sitespecific data, EPA appropriately did not include costs for entrainment technologies. This is 

because EPA cannot predict with confidence the outcome of the site-specific BTA entrainment 

standard-setting proceedings, and therefore, which facilities will undertake such installations 

and/or what installations they may undertake. As EPA indicated in the preamble, while not 

available nationally, EPA finds that closed-cycle cooling is the most effective technology for 

reducing entrainment. EPA notes that it did analyze9

 Option 2 which would have required flow 

reduction commensurate with closed-cycle at all facilities with 125 mgd or greater (Proposal 

Option 2), which account for 90 percent of actual flows. As indicated above, EPA cannot 

determine which facilities could not install CCRS, however Option 2 assumes all facilities not 

already CCRS would retrofit to CCRS. So, EPA can look to the costs of this Option and the 

projected impacts as an overestimated upper end bound of potential entrainment technology costs 

that could result from the site-specific determinations. See the EA and Essay 37. As explained in 

Essay 37, EPA determined the costs of Option 2 would not be large enough to adversely affect 

the economy. In addition, at proposal, EPA presented two hypothetical scenarios concerning 

additional costs some facilities might incur as a result of today’s BTA entrainment standard and 

we solicited comments on it. See 76 FR 22262-22263. EPA did not receive any comments or 

data showing that any of these hypothetical scenarios would adversely impact the economy. 

Definition of Existing Facility

Some commenters stated that all new modifications should be regulated as new facilities, since 

such modifications allow a facility to upgrade cooling technology. 

EPA’s Phase I rule established 316(b) standards for new facilities and defines facilities subject to 

that rule, including the circumstances where modifications to an existing facility are a new 

facility and when they do not. This final rule does not modify the definitions of new facility in 

the Phase I rule. This final rule establishes the BTA standards for existing facilities, including 

requirements for new units at such existing facilities. For further discussion see the preamble to 

the final rule. 

EPA does not agree with the comment that all modifications allow a facility to upgrade cooling 

technology. For example, a Type 3 “extended power” uprate at a nuclear facility may require 

significant modifications to the transformer or generator, and these major facility components 

have nothing to do with the existing cooling water intake structure system. Such modifications 

do not pose an opportunity for the facility to upgrade their cooling system technology. 

9

 EPA rejected closed-cycle as BTA (upon which Option 2 is largely based) based on three factors. See the preamble 

and Essay 19 for additional information. 

Essay 14 45 
CWIS

Some commenters asserted that the use of condenser cooling water from another unit is not using 

a CWIS. Some stated that the “not limited to” language in the proposed definition of CWIS 

means that the definition could include an entire facility, and suggested that EPA revise the 

definition to support one clear point of compliance. Some commenters stated that EPA has 

defined CWISs too broadly, including artificially constructed structures that have a low amount 

of aquatic life due to natural barriers, water depth, current and other factors. 

The comment does not make it clear how condenser cooling water from another unit would be 

reused. The rule provides that the recycling of treated effluent as cooling water does not 

constitute use of a cooling water intake structure (see 40 CFR125.91(c); also see the definition of 

“cooling water” in § 125.92). EPA disagrees with the approach that would define a single point 

of compliance for the reasons described above. As explained above, compliance is measured at a 

point depending on the impingement mortality and entrainment controls required for a particular 

facility. For the proposal, EPA defined CWIS broadly so as to able to address the full range of 

configurations and physical settings employed by existing facilities. EPA agrees, however, that it 

may have been overbroad and consequently has removed the “not limited to” language from the 

proposed definition of CWIS. As a result, the definition of CWIS is the same as the Phase I 

definition. The definition is consistent with the variety of technological configurations used by 

facilities that withdraw water through intake structure for use as cooling water in their 

operations. 

Definition of Cooling Water Intake

Twenty‐five (25) Percent Water Used for Cooling Purposes

Comments on the definition of cooling water addressed both the 25 percent water used for 

cooling purposes and the exemption of certain sources of cooling water. With regard to the 25 

percent requirements, some commenters stated that EPA should only regulate CWISs that 

withdraw exclusively cooling water (i.e., 100 percent cooling water). These commenters asserted 

that EPA lacks the authority to regulate process water intakes. Other commenters argued that a 

CWIS should not be regulated unless at least half (50 percent or greater) of the intake water is 

used for cooling (based on actual intake flow over 3-year operating basis). These commenters 

maintained that below 50 percent an intake is not a CWIS. Commenters stated that EPA needs to 

justify the 25 percent threshold for existing facilities, and noted that the 1977 guidance uses 50 

percent or greater. Commenters noted that at 25 percent (of 2 mgd) the threshold for rule 

applicability is in their view low (500,000 gpd) and further asserted that limited or no impact 

occurs at that level. Some argued that EPA’s rule is not consistent with the intent of section 

316(b) by including intakes that withdraw a majority of non-cooling water. Some argued that the 

threshold for cooling water use should be 5 or 10 percent, not 25 percent, since this would 

protect multi-purpose intakes. Some commenters suggested using AIF for percentage cooling 

water use to capture more CWISs. 

Some commenters asserted that an individual CWIS that withdraws less than 25 percent cooling 

water should not be subject to the rule requirements since the intake is not a cooling water intake. 

Some suggested that when assessing the 25 percent criterion, EPA should assess each CWIS 

individually. These commenters noted that the preamble supports this, although the rule indicates 

Essay 14 46 
the 25 percent criterion is applied facility-wide. In contrast, some commenters observed that it 

would be a burden to consider CWISs individually. Commenters also suggested that EPA should 

allow engineering estimates to determine 25 percent cooling water use since manufacturing 

industries do not always measure cooling water flow. Some commenters argued that EPA should 

allow a representative annual average over the previous 5 years to determine the 25 percent 

cooling water use. 

EPA does not agree with comments stating that the 25 percent threshold is inappropriate. As 

indicated in the preamble to this rule, EPA proposed, took comment, and finalized the 25 percent 

threshold in the Phase I, Phase II, and Phase III rules and has not received new information that 

supports changing this approach. As discussed in the preambles to the Phase I and Phase II rules 

(66 FR 65287-65288, December 18, 2001; 69 FR 41581 and 41611, July 9, 2004), EPA chose 

the 25 percent threshold to ensure that almost all cooling water withdrawn from waters of the 

United States is addressed under this section 316(b) regulation because cooling water 

withdrawals via CWISs is associated with adverse environmental impact. The preamble to the 

final rule explains in detail the nature of these effects. In addition, the EPA received extensive 

materials from commenters amplifying on the significant harm associated with the withdrawal of 

water for cooling. EPA consequently concluded that it is not reasonable to exclude from national 

regulations facilities that use significant quantities of cooling water and, as a result, impinge and 

entrain large numbers of aquatic organisms. 

EPA notes that it has provided incentives in the final rule to encourage recycle and reuse of 

water for cooling purposes. While a facility adopting some of these practices is still subject to 

requirements under section 316(b), in some cases these reuse measures alone could result in 

compliance with the BTA standard for impingement mortality. In other cases a facility could be 

out of scope (for example the facility no longer withdraws from a waters of the U.S.) and 

therefore is no longer subject to this rule because the definition of CWIS is not met. The EPA 

disagrees that the approach to multiple intakes poses excessive burden. More than 96 percent of 

existing facilities have 3 or fewer intake structures, and the vast majority of existing facilities 

only have a single CWIS; see TDD 4.1.5 and the discussion above on multiple points of 

compliance. Further, the facility has the option to comply on an intake basis or on a facility basis, 

as discussed above. The EPA disagrees that a CWIS must withdraw 100 percent of the water for 

cooling; such a requirement poses a loophole whereby a facility need use a small amount of 

water for some alternative purpose and thus be exempted from any requirements. The final rule 

provides that twenty-five percent or more of the water the facility withdraws on an actual intake 

flow (AIF) basis be used exclusively for cooling purposes. The rule defines AIF as an annual 

average over a specified time period (the three years preceding promulgation of the rule until 

five years after promulgation of the rule, at which time, the intake is averaged over the past five 

years). 

EPA notes that facilities that withdraw cooling water from waters of the United States and use 

less than 25 percent of water withdrawn for cooling still remain subject to 316(b) requirements 

established on a case-by case, best professional judgment (BPJ) basis. These facilities use 

cooling water and the intake of such cooling water may result in adverse environmental impacts. 

EPA notes that the Second Circuit has upheld the use of BPJ-based requirements for belowthreshold intake structures in its decision in Riverkeeper v. EPA, 338 F.3d 174, 203 (2d Cir. 

2004). 

Essay 14 47 
Scope of Exemption for Certain Waters

With regard to rule provisions that exclude certain water from the definition of cooling water, 

commenters offered different views. Some commenters asserted that exempting water from a 

public water system (PWS), reclaimed, treated effluent, or water used in a manufacturing process 

before or after use for cooling from the definition of cooling water for purposes of the 25 percent 

threshold is unacceptable because the overbroad exemption negates 316(b) protection wherever 

there is dual use, promotes energy intensive practices such as desalination, puts pressure on 

limited water resources, and violates restrictions on the use of restoration as an alternative to 

cooling water intake requirements. Some argued that excluding water from a PWS may shift the 

burden of regulation onto municipalities, who lack adequate resources. 

Some commenters recommended eliminating § 125.91(c) and § 125.92, which could function to 

narrow the scope of the rule some by providing that obtaining cooling water from certain sources 

(a public water system, using reclaimed water from wastewater treatment facilities or 

desalination plants, or recycling treated process wastewater effluent) does not constitute use of a 

cooling water intake structure. Similarly, one commenter argued that excluding water 

subsequently used for desalination from the definition of cooling water allows both the power 

plant and desalination plant to avoid regulation of water intakes altogether resulting in harm to 

aquatic organisms -- in California desalination plants are permitted assuming co-location with 

power plants subject to 316(b) -- and that water used for cooling remains cooling water. EPA 

disagrees that these provisions reduce the scope of the rule. These provisions do, however, 

function to ensure that water withdrawn exclusively for cooling is addressed, and by providing 

clarity as to how other sources of water used for cooling will be addressed by the rule. EPA has 

further made it clear that water obtained from these alternate sources (as well as cooling water 

used in a manufacturing process either before or after it is used for cooling) is considered process 

water, not cooling water, for the purposes of calculating the percentage of a facility’s intake flow 

that is used for cooling purposes (see § 125.92 – definition of “cooling water”). 

In contrast, some commenters maintained that the exemption for reused water is not broad 

enough. They indicated that process water from power stations, treated effluent from ash ponds, 

once used cooling water, reclaimed acid mine discharge, and treated effluent from wastewater 

treatment operations should also be excluded from being considered cooling water. 

Some commenters argued that reuse of cooling water that would otherwise be discharged from 

another unit is not using water for cooling purposes under this rule. They stated that EPA should 

exclude (in § 125.91(c) and § 125.92) all recycled effluent used as cooling water, not just treated 

effluent used by manufacturing and electric power facilities. Some commenters asked for EPA to 

clarify § 125.91(c). Others suggested that the rule should include a short term exclusion from 

rule requirements for times when reuse of water for cooling is not possible because such water is 

unavailable. This would avoid the need to shut down. 

Some commenters observed that EPA has not indicated how much time a facility has to adjust 

water use to potentially meet the reuse exclusion and get cooling water intake below the 25 

percent flow criterion. 

Essay 14 48 
Some commenters asserted that the exemption in § 125.94(d)(3) should apply to existing 

facilities and new units and address impingement and entrainment. Some asserted that dilution 

water should not be considered cooling water. 

Section 125.91(c) of the final rule provides that obtaining cooling water from a public water 

system, using reclaimed water from wastewater treatment facilities or desalination plants, or 

recycling treated effluent as cooling water does not constitute use of a cooling water intake 

structure for purposes of Part 125 subpart J. Section 125.92 provides that cooling water obtained 

from a public water system, reclaimed water from wastewater treatment facilities or desalination 

plants, treated effluent from a manufacturing facility, or cooling water that is used in a 

manufacturing process either before or after it is used for cooling as process water, is not 

considered cooling water for the purposes of calculating the percentage of a facility’s intake flow 

that is used for cooling purposes. EPA does not agree that these provisions are overbroad or 

negate 316(b) protection. After thorough consideration of the wide range of comments received 

on this issue, EPA determined these provisions do not exempt water withdrawn for cooling 

purposes from regulation. Rather, these provisions promote the reuse of water as cooling water 

and thus reduce the total amount of water withdrawn from waters of the U.S. solely for the 

purpose of once-through cooling and any environmental impacts associated with the withdrawal 

of additional water. In addition, some facilities already reuse water and EPA does not want this 

rule to discourage such beneficial reuse. 

With regard to reuse of cooling water by a desalination facility, EPA does not agree that the 

provisions in § 125.91(c) and § 125.92 are compliance alternatives that constitute after-the-fact 

restoration or that such reuse renders the rule ineffective. As discussed in the preamble, 

restoration as a measure to comply with BTA is not authorized under the Clean Water Act; 

therefore the final rule does not offer restoration as a compliance alternative. These provisions 

help define the applicability of the rule and, as noted, promote water reuse. 

This final rule does not apply to desalination plants that provide desalinated water to another 

facility as a source of cooling water. Regarding the reference to desalinization plants in § 

125.91(c), the EPA’s authority is limited to cooling water intakes and thus does not otherwise 

apply to desalination plants where they do not withdraw water for cooling purposes. EPA notes 

that typically a desalination facility will reuse cooling water from a power plant after it has 

served its cooling function (energy conservation is achieved through the reuse of heated water). 

The regulation simply explains that (under the statute) a desalinization plant’s use of water is not 

for cooling, and although the water was once used for cooling, the water is not subject to 316(b) 

when it is accepted by the desalination plant. See the Big Bend (Tampa Bay, Florida) Site Visit 

Report (DCN 10-6502). 

In addition to PWS and desalination plants discussed above, other sources of water may be 

available for reuse or recycle as cooling water such as treated effluent from a manufacturing 

facility or a municipal wastewater treatment plant. Today’s final rule specifies that using treated 

effluent (such as wastewater treatment plant gray water) as cooling water does not constitute use 

of a CWIS for purposes of this rule. As a point of clarification, facilities subject to today’s rule 

may choose to use another entity’s treated wastewater as a source of cooling water, thereby 

reducing cooling water withdrawals and associated impingement and entrainment. EPA notes 

that because the entity providing the wastewater for cooling has already treated it to meet any 

Essay 14 49 
applicable discharge requirements (e.g., otherwise applicable effluent limitations guidelines and 

standards, water quality standards, etc.), EPA is not concerned that this provision will lead to 

pollutant discharges that would not have occurred if the treated effluent had been discharged by 

the other entity. 

As explained above, treated effluent from a manufacturing facility, or cooling water that is used 

in a manufacturing process either before or after it is used for cooling as process water, is not 

considered cooling water for the purposes of calculating the percentage of a facility’s intake flow 

that is used for cooling purposes in 40 CFR 125.91(a)(3). Using treated process wastewater or 

recycling treated process wastewater effluent as cooling water does not constitute use of a 

cooling water intake structure under this rule. Electric generating facilities that withdraw or use 

treated effluent from ash ponds for use as cooling water may not be subject to this part for that 

volume of cooling water reused. Section 125.91(c) could include power station process water 

that is reused for cooling, although the quantities of such process water are typically too small to 

replace a power plant’s needs for cooling water. It is not clear in the comments if the reclaimed 

acid mine discharge is first treated, but EPA expects the provisions can be applied to any 

reclaimed water that meets the definitions and requirements of Part 125. 

In addition, in the definition of cooling water at § 125.92, EPA specifically addressed the use of 

cooling water in manufacturing processes before or after cooling because this is the most 

prominent reuse of water, and this reuse is the most likely to involve significant volumes of 

water reused for cooling purposes. Under this final rule, less water would be withdrawn overall 

as manufacturers would not need to withdraw water solely for the purposes of cooling, reducing 

the environmental impacts associated with the additional water withdrawals for cooling. EPA 

disagrees that such a provision would allow manufacturers to avoid regulation, as manufacturing 

facility discharges are already subject to effluent guidelines, water quality standards, and other 

state and local requirements. Such discharge standards, in combination with the cost of treating 

water for use as process water, form a strong disincentive for process water withdrawals beyond 

what is minimally necessary at a given manufacturing facility. Further, EPA found in site visits 

that many manufacturers conduct water and energy audits, and subsequently found that some 

manufacturing industries have significantly reduced water flows; see 76 FR 22189 for further 

discussion of the paper and the iron and steel industries. Upon consideration of each of these 

rationales, EPA has finalized a definition of cooling water at 40 CFR 125.92 to provide further 

incentives for reusing and recycling water flows. 

The final rule specifies that the schedule for compliance with permit requirements implementing 

the BTA standards for impingement and entrainment will be determined by the Director. The 

various permit application requirements at 40 CFR 122.21, 125.94 and 125.98, in some cases, 

require development of studies that may take months or years of collecting and compiling data; 

see preamble section on Implementation. As discussed in the preamble, this may be as short as 6 

months to compile existing data and submit required reports. This period may be as long as 45 

months for full permit application materials at some facilities, such as those that need to develop 

a plan for sampling, conduct the sampling, and generate a peer-reviewed final report. In the case 

of permits issued before 45 months after the effective date of the final rule, the rule at 40 CFR 

125.98(b)(5) provides the Director with the discretion to establish an alternate schedule for 

submission of the required elements of the permit application. All permit application materials 

must be submitted with the permit application, however, under § 125.95(a)(2) the owner or 

Essay 14 50 
operator applying for a permit expiring prior to a date 45 months after the effective date of this 

rule may request an alternate schedule for the submission of the required information. For 

specific discussion of each of the main permit application requirements, see the implementation 

section in the final preamble. 

The final rule does not specifically address situations where a facility that normally reuses water 

cannot do so for a temporary period of time and as a result may meet an applicability threshold. 

It should be noted that the 25 percent cooling water use requirement is based on AIF, and AIF is 

defined on an average annual basis over five years. Commenters did not provide data showing 

situations where temporary changes in AIF would tip the facility over the applicability threshold 

so as to make it subject to the final rule’s requirements. 

Some commenters asserted that industrial customers of a city (or a private) raw water surface 

supply system (with CWIS) should not be subject to the rule just because they have a NPDES 

permit for wastewater discharge. EPA disagrees. A third party supplier is withdrawing cooling 

water and these withdrawals have the same deleterious effect on the waterbody as any other 

intake structure. Under the rule, a facility is “using a cooling water intake structure” and 

potentially subject to the final rule if it obtains cooling water by contract or arrangement with 

one or more independent suppliers of cooling water if the independent supplier withdraws water 

from waters of the United States but is not itself a new or existing facility as defined in 40 CFR 

Part 125 subparts I or J. This is intended to prevent an owner or operator of an existing facility 

from circumventing the rule requirements by creating arrangements to receive cooling water 

from an entity that is not itself a facility subject to subparts I or J. See the preamble for additional 

discussion. 

Applicability to Point Source Discharges

Some commenters asserted that the rule requirements should not apply to facilities that do not 

have a NPDES permit for a discharge to water of the United States. Other commenters argued 

that the rule should not apply if the only NPDES permit held by a facility is for stormwater. 

EPA disagrees with the comments. Section 316(b) states, in full: 

Any standard established pursuant to section 301 or section 306 of [the Clean Water] Act 

and applicable to a point source shall require that the location, design, construction, and 

capacity of cooling water intake structures reflect the best technology available for 

minimizing adverse environmental impact. 

As noted, the final rule applies to specified facilities that, among other things, are a point source 

as defined in CWA section 502 and in the EPA’s NPDES regulations at 40 CFR 122.2. 

Necessary conditions to implement the final rule must be included in the NPDES permit of 

facilities subject to the rule. The independent supplier provisions in the rule prevents 

circumvention of the rule requirements by a facility making arrangements to receive cooling 

water from an entity that is not itself a facility subject to 40 CFR 125 subparts I or J. With regard 

to facilities with only stormwater permits, EPA has determined that given the requirements of 

section 316(b) and the fact that the referenced standards are implemented through NPDES 

permits, it is appropriate to implement the requirements of the final rule to any a facility with a 

Essay 14 51 
NPDES permit where the facility uses a CWIS to withdraw cooling water from a water of the 

United States and is otherwise subject to the rule. The final rule establishes requirements 

designed to minimize the adverse impacts associated with the use of cooling water. There is no 

demonstrated relationship between these adverse impacts caused by intake of cooling water and 

whether discharges are continuous or intermittent. There is no basis for not subjecting a facility 

that withdraws significant volumes of water for cooling from the final rule merely because it 

only discharges stormwater. 

Least Energy Demanding Source of Water

Some commenters suggested that alternative sources of water used for closed-cycle cooling 

should be prioritized to require the least energy demanding source. The commenter did not 

provide data or specific suggestions on how to analyze such a requirement. 

EPA does not agree that the requirements of the final rule should be further tailored in the 

manner suggested by certain commenters. EPA lacked adequate data to formally evaluate such 

an approach at this time. The EPA has concluded, however, that the final rule will promote water 

reuse consistent with achieving the authority objectives of section 316(b). 

Exemptions

Some commenters requested that EPA exempt various intakes, structures, and waters. 

Commenters suggested that EPA exempt deep water CWISs, since in the commenter’s view 

these cause very limited impact. Some comments requested that EPA exempt source waters that 

do not have aquatic and wildlife designated uses. For example, commenters pointed out that 

Phoenix Arizona irrigation canals are man-made lined canals that are waters of the United States 

but that do not have aquatic and wildlife designations (because they are not natural, they are 

cement lined, they dry up, and they are only used for domestic and agricultural uses) and, thus, 

CWISs located on these canals should not be subject to the rule. Other commenters asserted that 

EPA should exempt irrigation supply canals, hydroelectric supply canals, and other supply canals 

where CWIS impact is negligible, or allow the permit authority to either exempt these waters or 

to determine site-specific requirements. Some commenters suggested that EPA exempt quarries 

or other manmade structures used to access groundwater. Finally, some commenters asked EPA 

to exempt the use of any effluent, not just treated effluent. 

EPA disagrees with the comment regarding deepwater CWISs. EPA notes the commenter did not 

include data supporting its assertion of limited impact. According to data in EPA’s record, 

SEAMAP data showing that longer distances offshore (1) change the species subject to adverse 

environmental impact and, further; (2) on a organisms density basis, the aquatic life density is 

not adequately reduced by distance offshore. Also see the preamble for a discussion of why 

offshore velocity caps themselves do not minimize adverse effects to aquatic organism on the 

basis of intake location alone. After reviewing available data, the final rule, has not categorically 

exempted deep water CWISs from meeting applicable standards. 

In the rule EPA has not exempted intakes on source waters that do not have aquatic and wildlife 

designated uses. EPA disagrees that source waters that do not have aquatic and wildlife 

designated uses should be exempt. EPA does not consider such an approach to be consistent with 

Essay 14 52 
the objectives of the CWA, and further notes that waterbodies and waterbody classifications can 

evolve over time. However, the rule is sufficiently flexible to address these situations. For IM, 

facilities may have located the intake structure to reduce impingement in the first place; as 

discussed above, § 125.94(c)(6) “system of technologies” allows facilities to take credit for such 

reductions. Furthermore, the impingement mortality requirements include a de minimis rate of 

impingement provision that can allow the Director to determine that no additional controls where 

the documented rate of impingement is so low that no additional controls are warranted. The 

entrainment requirements for existing facilities are to be determined on a case-by-case basis; this 

allows the Director to consider any impacts of the CWIS. Such a determination could include 

consideration of technologies such as the intake location, as well as the relationship of costs to 

benefits. 

With respect to quarries or other manmade structures used to access groundwater, EPA notes that 

the rule applies to the use of CWISs to withdraw water to be used for cooling from waters of the 

United States. Waters of the United States (WOUS) are defined at 40 CFR 122.2 and do not 

include ground water. As a point of clarification, groundwater itself is not a WOUS. But, for 

example, perennial streams are fed by groundwater and the perennial streams are WOUS 

(presuming flow into a traditional navigable water eventually). So, a quarry fed by groundwater 

could be a WOUS if it has a significant nexus to a traditional navigable water. A quarry that is 

truly isolated with no connection to a nearby tributary, would unlikely be a WOUS). 

Public Water Systems

Commenters also addressed how water from public water systems is addressed under the rule. 

Some commenters stated that EPA should define and clarify the public water system (PWS) 

exception so that ownership and maintenance of pumps and related equipment at an intake 

owned and operated by a PWS does not negate the exception (clarify how the rule would apply 

where an intake is not owned by the facility but the pumping system is, and cooling water and 

other water is both used and shared with other entities). Some commenters asked that EPA not 

limit the definition of PWS to serving residential customers. They suggested that EPA define 

PWS as a public or quasi-public entity that provides water to the public or a subset of the public 

(not limited to residences). These commenters observed that there are many independent 

suppliers of water to manufacturers that do not supply potable water (multiple uses) and that this 

is not done to avoid regulation. Other commenters made a similar point in that PWS should 

include supplying water for purposes beyond drinking (e.g., irrigation canals). Some commenters 

asked whether EPA intends to use the SDWA definition of PWS. 

Under § 125.91(c) and § 125.92 (definition of cooling water) the rule refers to PWSs. The term 

PWS is defined under the SDWA regulations and generally refers to drinking water systems of a 

certain size (see 40 CFR 142.2). EPA references PWSs in the above-referenced provisions 

because these are established terms and reflect potential reuse of PWS-derived water for cooling. 

EPA notes that the CWIS is defined as including the pumps. However, the split-ownership 

example is not sufficiently detailed to address here. The application of the rule in the 

commenter’s example would have to be determined by the Director. Subsections 125.91(c) and 

125.92 address the reuse of cooling water before or after manufacturing, so there is no need to 

expand the definition of PWS under this rule to include entities that provide non-potable water to 

Essay 14 53 
manufacturers. Systems used to supply irrigation water only are not PWSs. Such systems could 

potentially constitute an independent supplier. 

Commenters also raised several additional points. Some commenters indicated that § 125.91(c) 

exempts CWIS where once-through treated effluent is used for makeup water. Some asserted that 

only intakes on the same source waterbody should be counted together to determine if a facility 

meets the flow threshold, since impacts are waterbody-specific. Some commenters observed that 

the rule may promote use of groundwater for cooling, which conflicts with Louisiana’s efforts to 

use groundwater for potable water. Commenters also sought clarification about the status of 

treated WWTP effluent that is not de-chlorinated. 

One commenter suggested that EPA should prohibit use of freshwater for once-through cooling 

and should define BTA to require use of reclaimed water since such reuse is a proven beneficial 

technology, reclaimed water is widely available at once-through facilities, EPA’s concerns about 

reclaimed water availability are unsupported and unwarranted, and the use of reclaimed water at 

closed-cycle facilities addresses consumption issues. At a minimum, the comment suggested that 

the rule could create a preference for reclaimed water similar to a California program. Other 

commenters pointed out that a sufficient quantity of water that can be recycled may not be 

available, and that recycling should not be mandated but should be driven by local economics. 

Finally, some commenters suggested that EPA should provide flexibility to use BPJ when 

permitting shared intakes used by co-located entities. Commenters asserted co-located entities 

were not addressed by the proposed rule. 

Subsection 125.91(c) in part provides that the use of treated process wastewater effluent is not 

considered cooling water for purposes of determining whether a facility is subject to this rule. 

However, under this provision the CWIS is not exempt as indicated in the comment; rather, the 

water used for cooling is not considered cooling water for purposes of determining the 

applicability of the rule. With regard to the assertion that the applicability threshold should be 

applied on a waterbody-specific basis, EPA disagrees. EPA maintains that the threshold reflects 

a level of adverse impact and it is important to have a single, consistent threshold for 

applicability of the rule. Establishing waterbody-specific thresholds would introduce a further 

measure of complexity that is not necessary. In addition, such an approach could result in a 

facility with multiple intakes where each intake is located in a different waterbody, or through 

creation of multiple smaller intakes in lieu of one single intake. 

The final rule is not intended to, and does not promote the use of, groundwater for cooling. 

Rather the EPA recognizes that, in particular circumstances, there may be different sources of 

cooling water, and this rule preserves the flexibility of existing facilities to avail themselves of 

difference sources for cooling water while providing incentives for use of certain forms of water 

reuse. States can and are in a better position to promote the use and protection of groundwater 

resources. 

As discussed in the preamble to the final rule, EPA has not adopted closed-cycle recirculating 

(including dry cooling) as BTA entrainment standard on a national basis. EPA has determined 

closed-cycle is not BTA on a national basis for the reasons specified in section VI of the 

preamble. Moreover, the availability or non-availability of reclaimed water is not one of the 

Essay 14 54 
factors EPA concluded was a determining factor in its decision not to establish a national 

standard for entrainment based on closed-cycle recirculating systems. Even if sufficient volumes 

of reclaimed water were available, and the reclaimed water meets the quality of water needed by 

facilities for cooling, closed-cycle is still not BTA on a national basis. Therefore, EPA disagrees 

that it is a feasible option for BTA for entrainment based on a prohibition on the use of surface 

water withdrawals for once-through cooling and rely solely on reclaimed water. Some facilities 

that need cooling water are not located near a source of reclaimed water, or the source may be 

insufficient quantity or quality for use as cooling water. 

EPA agrees that the use of reclaimed water for cooling should be encouraged. This rule is 

structured to allow and promote the use of alternative sources. EPA acknowledges that in some 

geographical areas a sufficient surface water supply may not always be available (e.g., see record 

for examples of recent facilities using ground water, dry cooling, etc.) and alternatives must be 

used. With regard to a preference for reclaimed water, this rule includes provisions (§ 125.91(c) 

and § 125.92 (definition of cooling water)) that may reduce the applicability of the rule based on 

the use of reclaimed, reused, or recycled water. EPA maintains that this is a significant incentive 

to use such sources of water. In addition, water reuse must be considered as on element under the 

rules permit application requirements for large flow facilities. Additional water reuse can be 

achieved by existing facilities, and this rule promotes such reuse. Thus, the use of reclaimed 

water should be considered, particularly in states or regions that have limited surface waters 

and/or a preference for the use of reclaimed water. However, based on present cooling water 

demand, EPA disagrees that sufficient quantities of reclaimed water exist that can be recycled to 

satisfy the demand of all existing facilities subject to 316(b). As discussed above, even if such 

quantity and quality of reclaimed water was available, it would not change EPA’s basis for 

determining closed-cycle is not BTA. See also the discussion of reclaimed water in Essay 18. 

Waters of the United States

Some commenters addressed the criterion of withdrawing cooling water from a water of the 

United States. Some indicated that EPA should explicitly state that the withdrawal of water from 

discharge canals, impoundments, quarries, municipal water, wells, and other waters that are not 

waters of the United States do not result in the use of a CWIS and are therefore not subject to 

rule. Other commenters observed that EPA’s reliance on waters of the United States guidance is 

not appropriate since there are multiple guidance documents, such guidance often changes over 

time, and EPA has not provided sufficient notice of this approach and the guidance. 

As explained in the preamble, the final rule applies only to withdrawals of cooling water from 

waters of the United States. This rule does not define, alter, or in any way change what 

constitutes a waters of the United States. The determination of what is and what is not a water of 

the United States is a site-specific determination that will be made based on applicable law, 

regulations, and legal decisions, as well as relevant guidance. This rule uses the term “waters of 

the United States” and that term is defined in EPA regulations (40 CFR 122.2). Any guidance 

that is used to help determine what is a water of the United States is based on the applicable law 

and regulations. 

Essay 14 55 
Independent Supplier

Comments addressed the independent supplier provision in the proposed rule as well. Some 

commenters explicitly supported the applicability of the rule to independent suppliers. Some 

commenters suggested that EPA grandfather the use of independent suppliers since a facility 

lacks control of its water supplier and for a facility to avoid use of the supplier the facility would 

have to build a costly new intake. Other commenters stated that the implementation timing 

should be based on the independent suppliers permit renewal schedule. 

Some commenters argued that EPA should exclude CWISs operated by independent suppliers. 

They asserted that a facility may not have authority over or access to an independent suppliers 

CWIS and therefore cannot control the independent supplier. Only facilities that own and 

operated CWIS should be subject to the rule. Commenters asserted that EPA cannot regulate a 

third party supplier through a NPDES permit for a 316(b) facility. Some commenters sought 

clarification for when an independent supplier does not meet applicability criteria (e.g., has 

NPDES permit but itself uses less than 2 mgd). 

Some commenters argued that EPA should regulate PWSs, or exclude independent suppliers, for 

logical consistency. These commenters stated that PWSs cause AEI too. Other commenters 

observed that to achieve consistency, the definition of independent supplier should exclude PWS. 

Some argued that because PWSs cause AEI they should not be excluded. 

As explained in the final rule, EPA included the independent supplier provision to prevent 

existing facilities from attempting to circumvent the rule by creating arrangements to receive 

cooling water from an entity that is not itself a facility subject to Part 125 subparts I or J. The 

316(b) standards for new facilities include a similar provision. The final rule does not 

grandfather independent suppliers and EPA does not agree that this provision requires existing 

facilities to build new intakes. Rather, existing facilities should ensure that independent suppliers 

meet applicable permit requirements including requirements applicable to in-scope CWISs. 

Similarly, the timing of the rule is based on the permit issued or held by the existing facility, not 

the independent suppliers, since the rule focuses on water used for cooling at existing facilities. 

EPA recognizes that existing facilities may not always control an independent supplier. The 

existing facility remains responsible for ensuring that any CWIS used by the facility, including a 

CWIS operated by an independent supplier, meets the requirements of this rule as expressed in 

an NPDES permit. With regard to PWSs, EPA has concluded that it is not necessary to regulate 

PWSs or exclude independent suppliers under the rule. Although EPA recognizes the PWS 

intakes can cause adverse impacts, PWSs are not regulated under this rule because they do not 

withdraw water for cooling. Section 316(b) requires EPA only to establish standards to address 

the intake of cooling water under 316(b). See previous discussion regarding language of section 

316(b). EPA allows the reuse of water from a PWS because such reuse reduces the overall need 

for additional water withdrawals that may be associated with adverse environmental impacts. In 

contrast, EPA has addressed the situation in which a facility obtains cooling water from an 

independent supplier under the rule because EPA does not want existing facilities to circumvent 

the rule by obtaining cooling water from another entity that is not subject to 316(b) requirements 

and that does withdraw cooling water. EPA has added language to the independent supplier 

definition that excludes PWSs from requirements applicable to cooling water intake structures. 

Further, the existing facility must meet the applicability criteria, not the independent supplier 

(assuming such supplier is not independently subject to 316(b) requirements). Thus, in the case 

Essay 14 56 
of an independent supplier withdrawing more than 2 mgd for use by the existing facility then, 

assuming all other applicability criteria are met, the existing facility would be subject to 316(b) 

requirements under today’s rule. If the independent supplier withdraws less than 2 mgd,), the 

permit writer will establish requirements for the facility using water from the third party supplier 

on a case-by-case (BPJ) basis. 

Impoundments/Definition of CCRS

Commenters provided a range of comments regarding the definition of closed-cycle recirculating 

systems (CCRSs) and the use of impoundments. Some commenters requested that EPA clarify 

whether a cooling pond is a CCRS and the point of compliance for facilities that rely on 

impoundments for some or all of their cooling water. Other comments sought to clarify how the 

rule applies to a cooling pond with two sets of intake pumps (river to pond; pond to facility). 

Commenters also asked whether auxiliary intakes used during drought for makeup water are 

subject to the rule. Comments regarding point of compliance are discussed above in this essay. 

Comments specifically regarding impoundments are discussed below. 

Closed‐Cycle Cooling Definition is Too Narrow

Some comments argued that the proposed rule definition of a closed-cycle recirculating system is 

too narrow, thereby excluding many ponds and basins built for cooling. These commenters 

observed that the definition should allow for other uses of makeup water beyond “blowdown, 

drift and evaporation”, such as water stored in impoundments. In addition, it should clearly allow 

other uses, including service water, emergency back-up and fire protection, facility maintenance 

and sanitary uses (also screen washing, air preheater washing, boiler makeup, wetlands 

rehydration). Some suggested that the EPA should clarify that the withdrawal of small amounts 

of service water is allowable. 

Comments also addressed whether a closed-cycle system can be a water of the United States. 

Some commenters stated that a pond or reservoir should not be excluded from being a CCRS 

based on their classification as a water of the United States. Rather, commenters assert the 

definition should be broad and include impoundments and reservoirs regardless of their status as 

a water of the United States. Commenters argued that the waters of the United States restriction 

is unreasonable and likely to adversely affect public access to privately owned waters. Others 

argued that man-made lakes built to cool power stations do not constitute waters of the United 

States. Some commenters observed that converting impoundments built as closed-cycle cooling 

systems to open-cycle systems would increase costs and may constitute a taking under the Fifth 

Amendment. They noted that defining CCRS as excluding waters of the United States expands 

EPA jurisdiction over waters of the United States. Other commenters added that under EPA 

regulations water of the United States do not include “waste treatment systems” and EPA has 

recognized that the CWA does not require the application of technology-based requirements at 

the point of discharge into constructed waterways designed to serve as waste treatment systems. 

They stated that impoundments are designed to treat heat (a pollutant) as part of the NPDES 

system and that impoundments are waste treatment systems that are excluded from the definition 

of water of the United States. Some commenters maintained that EPA should state that the 

jurisdictional status of impoundments will not be reopened. Other similarly argued that 

impoundments that were not themselves waters of the United States when they were built should 

Essay 14 57 
be defined as CCRS. Some went so far as to suggest that EPA require no controls for existing 

reservoirs constructed by power generators for cooling. 

EPA does not agree that the definition of closed-cycle recirculating system (CCRS) is unduly 

narrow. The final rule definition includes impoundments that are not waters of the United States. 

This definition does not impose additional requirements on such impoundments; rather it 

acknowledges that the use of such impoundments as a properly operated closed-cycle system is 

deemed to meet certain requirements of the rule. Although the definition requires makeup be 

minimized and provides for the replacement of water lost due to evaporation, the final rule also 

allows for such systems to replace other water losses provided the facility demonstrates to the 

satisfaction of the Director that makeup water withdrawals attributed specifically to the cooling 

portion of the cooling system have been minimized. EPA acknowledges water may be used for 

purposes other than for cooling, and distinguishes between makeup water for cooling and water 

for other purposes. These provisions accommodate reasonable other uses of such ponds and 

basins, including secondary uses associated with facility support. See the final definition of 

CCRS. 

EPA is aware of the language addressing waste treatment systems at the end of the definition of 

waters of the United States (40 CFR 122.2), including the fact that the definition of 

impoundments referenced no longer exists in section 423, and that the limitation of the exclusion 

to man-made bodies of water not created in a waters of the United States or resulting from the 

impoundment of a waters of the United States was suspended in 1980 (see note at end of § 

122.2). Given the mandates of the CWA to protect jurisdictional waters, EPA does not view the 

waste treatment exclusion as applying to impoundments that otherwise meet the definition of 

waters of the United States. This determination will continue to be made on a case-by-case basis. 

The definition of CCRS in the final rule includes impoundments that are not waters of the United 

States. A CCRS cannot include waters of the United States because protection of waters of the 

United States from adverse environmental impacts is the endpoint of the standards required by 

section 316(b). Under section 316(b), EPA must establishment requirements that ensure that the 

location, design, capacity and construction of CWISs reflect the best technology available to 

minimize adverse environmental impacts to waters of the United States. EPA has previously 

noted that, for purposes of section 316(b), the determination of what is and what is not a water of 

the United States is a case-by-case determination. EPA notes that whether or not a waterbody is 

man-made is not, in and of itself, a determinative factor in the definition of waters of the United 

States (e.g., the definition includes impoundments of waters otherwise defined as waters of the 

United States). 

The EPA finds that many comments interchange the terms cooling pond and cooling lake, and 

for purposes of this essay EPA is not distinguishing between the two. A cooling pond is an 

impoundment used either in lieu of a cooling tower or as a supplement to a cooling tower to 

remove waste heat from the plant. Many power plants also use impoundments to reduce the 

temperature of the cooling water exiting the plant before it is discharged back into a receiving 

waterbody. The pond dissipates waste heat through the surface of the pond, resulting in some 

evaporative losses. Therefore, a cooling pond requires additional makeup water from another 

source. EPA’s record shows the makeup water is frequently obtained from a water of the U.S. 

Essay 14 58 
(46 power plants and 34 manufacturers withdraw from a water of the U.S. as makeup water for a 

pond). 

The EPA is not determining which ponds are waters of the U.S. in this rule. In the final rule, 

EPA assumed approximately 60 facilities with impoundments would meet the definition of 

CCRS, and therefore did not assign technology costs to these facilities. An additional 40 

facilities use more than one cooling water system, and these facilities were assigned compliance 

technology costs. As a sensitivity analysis, EPA assigned all ponds with compliance technology 

costs. EPA notes these costs are a small portion of the total national rule costs because CCRSs 

using ponds comprise approximately 2 percent of all facilities (less than 7 percent of the 31 

percent of existing facilities that currently use CCRSs, noting cooling towers comprise the other 

remaining 24 percent). See the memo to record entitled “Social Costs for Final Rule and Other 

Options Considered with and without Impoundments Provision” for more details. 

EPA does not agree that this aspect of the rule constitutes a taking. The final rule does not result 

in taking any property from a facility for public use. Whether an impoundment is a CCRS, as 

well as whether the impoundment is a water of the U.S., does not affect whether a facility 

chooses to provide public access and use of that impoundment. 

EPA does not agree that the definition of CCRS expands EPA’s jurisdiction over waters of the 

U.S. To the extent that some facilities have not treated certain impoundments as waters of the 

United States that are now subject to requirements as does not represent a change in or extension 

of the Agency’s jurisdiction under section 316(b).The determination of what requirements of this 

rule apply at a particular facility will be decided by a permit writer. In that proceeding, the 

permit writer may have to address whether use by a particular facility of an impoundment as part 

of its CCRS reflect use of waters of the U.S. or not. 

Man‐Made/Managed Impoundments

Numerous comments addressed man-made impoundments and impoundments. Several 

commenters maintained that the rule does not adequately address unique waterbodies resulting 

from man-made reservoirs built for use as cooling water impoundments. They argued that these 

waters are not comparable to natural lakes and reservoirs and that the rule applies excessive 

protection, considering the highly managed nature of these impoundments. Some commenters 

suggested that the rule should exempt man-made lakes. Others suggested the rule should allow 

for BPJ and/or flexibility for such impoundments. For example, commenters observed that Texas 

has 33 reservoirs created for cooling which are different than natural waterbodies although they 

are managed to serve multiple functions. They noted that some impoundments in Texas circulate 

their entire contents in 7-32 days and still maintain vibrant aquatic ecosystems. Some 

commenters stated that most ponds built for power plants in Texas meet the functional definition 

of CCRS but not the actual definition due to their status as waters of the United States. They 

asserted that EPA should identify these as providing BTA cooling water use or otherwise allow 

for their continued use. Commenters asserted that man-made off channel impoundments in Texas 

have created fishing resources and continue to function effectively despite use for cooling for 

many years. They also indicated that Texas data for inland facilities from 2005 to 2008 indicate 

that over 85 percent of impinged fish are threadfin shad (a stocked forage fish). Commenters 

stated that for this species, the proposed impingement rates would be unachievable. Some 

Essay 14 59 
asserted that any AEI should be balanced against the biological communities created in many 

cooling impoundments. Others argued that the rule would regulate man-made waterbodies with 

very limited ecosystems that are inaccessible to the public and such regulation is of no benefit to 

the public. Additional flexibility (impingement and entrainment requirements, cost/ benefit) 

should be provided where a cooling pond is operated as a managed fishery. Impingement and 

entrainment standards should not be imposed on CWISs located on freshwater lakes with state 

managed fisheries. 

EPA is aware that man-made impoundments and impoundments exist and that these 

impoundments vary in size and characteristics, with some managed for multiple uses (i.e., 

cooling and recreation). As discussed above, the CWA focuses on the protection of waters of the 

United States and, as a result, the definition of closed-cycle recirculating system in the rule does 

not include impoundments that are waters of the United States. The rule does not exempt manmade impoundments if such ponds meet the definition of waters of the United States. Nor does 

this rule alter the definition of waters of the United States. 

EPA agrees that artificially managed reservoirs may be different than natural lakes, therefore, 

EPA has discussed in the preamble and provided in the final rule that the Director may waive 

some or all of the information requirements of 40 CFR 122.21(r) if the intake of concern is 

located in a manmade lake or reservoir, and the fisheries are stocked and managed by a State or 

Federal natural resources agency or the equivalent. Although this provision does not relieve any 

facility of the requirement to comply with the BTA standards of the rule, it does provide the 

Director with the ability in certain cases (e.g., where the biological characterization of the source 

water is significantly influenced by the actions of the natural resources agency) to reduce 

information required for the facility’s permit application. EPA notes that the impingement 

mortality and entrainment requirements of the rule provide flexibility through compliance 

alternatives and site-specific entrainment determinations. Directors may use this flexibility to 

address man-made impoundments. For example, with regard to the impingement data from 

Texas, the rule includes six impingement compliance alternatives other than meeting the numeric 

mortality performance standard (e.g., a facility could meet the through-screen velocity or install 

any combination of technologies that the permit writer determines achieve a BTA impingement 

mortality performance for the site). 

EPA disagrees that facilities on man-made or managed fresh water lakes and reservoirs could not 

meet the IM performance standard. The final rule replaces the species of concern approach from 

the proposed rule with a more precise and transparent definition for fragile species. Further, EPA 

has dropped the monthly limit from the final rule, and replaced the annual requirement with a 12­

month percent survival. Requirements for threadfin shad (a fragile species) would be determined 

by the Director. As discussed above, the Director may reduce permit application studies and 

requirements where the freshwater lake/reservoir is managed by a state resource management 

agency. The final rule provision allows the Director to consider the value of biological studies of 

artificially managed ecosystems, particularly where the biological study is made obsolete by 

restocking of select fisheries. With respect to entrainment, the Director already will make a 

determination of BTA as discussed further below. 

With regard to setting BTA based on balancing AEI with the recreational benefits of man-made 

reservoirs, such an approach is not consistent with section 316(b), which mandates that EPA 

Essay 14 60 
establish standards representing the best technology to minimize AEI. However, under the final 

rule, the BTA standard for entrainment requires determination of site-specific entrainment 

controls in a structured proceeding that must take into account a number of factors including the 

costs and benefits of different approaches to entrainment reduction. Thus, certain benefits (e.g., 

benefits to recreational species, benefits to the environmental local communities) associated with 

entrainment reduction technologies and operational measures may be considered by the Director 

as a elements in evaluating BTA for entrainment. The final rule provides that the Director in 

evaluating available entrainment technologies may consider other relevant factors including 

social benefits under § 125.98(f)(4). In some circumstances, these benefits may be identified as 

part of the benefits valuation study required as part of the permit application for certain facilities 

at 40 CFR 122.21(r)(11). Where an impoundment is inaccessible, it is unclear whether such a 

waterbody would meet the definition of a water of the United States. 

Intermittent Flow in a Closed‐Cycle Recirculating System

Comments also addressed the intermittent flow provision in the definition of closed-cycle 

recirculating system. Some commenters asserted that a prohibition against any level of 

continuous flow is unreasonable. Commenters argued that some ponds withdraw a continuous 

flow because this protects the source waterbody. Commenters argued that there is no reason why 

a closed-cycle recirculating system has to have an intermittent flow of makeup water, but there 

are reasons why a consistent flow may be desirable. Commenters noted that limiting makeup 

water to replenishment of certain losses will interfere with common power plant practices. 

The commenter appears to misunderstand the rule definition. The definition of closed-cycle 

recirculating system does not require an intermittent flow in the final rule. In addition, the final 

definition provides flexibility so that replenishment can extend to losses beyond blowdown, drift 

or evaporation in specified circumstances. Such replenishment is not prohibited by the final rule. 

Under the final rule, in evaluating whether a particular cooling water intake structure represents a 

CCRS, the Director will determine whether such withdraws are for cooling purposes and thus are 

attributable to a determination that the withdrawals constitute minimized makeup. 

Additional Suggestions on Requirements for Closed‐Cycle Recirculating Systems

Comments included numerous suggestions regarding requirements for closed-cycle systems. 

EPA notes that these suggestions assume that all impoundments comprise a closed-cycle system, 

a position with which EPA does not agree. Some commenters indicated that EPA should create 

reasonable presumptions that provide certainty for facilities that use impoundments. Some 

asserted that a cooling pond that functions as a closed-cycle recirculating system (water use 

reduced by 96.6 percent) should not be required to do more since any benefits do not justify the 

costs. Similarly commenters maintained that no additional controls should be required for 

facilities with constructed cooling reservoirs that use/are closed-cycle recirculating system since 

these are BTA. Commenters also asserted that EPA should exclude regulation of intakes in 

dedicated impoundments or allow for site-specific determination by permitting authority. 

Some commenters asserted that EPA should eliminate the entrainment requirements if a cooling 

pond has a retention time of 7 days or more. Others suggested that the regulation of intakes for 

makeup water should be left to the states that are familiar with local water issues. Finally, some 

Essay 14 61 
asked whether blowdown was intended to address overfilling a pond to reduce TDS and, if not, 

suggested that EPA modify the definition to include such an operational control. 

EPA has made it clear that a facility that uses a closed-cycle recirculating system, as defined in 

the rule, would meet the rule requirements for impingement mortality at § 125.94(c)(1). This rule 

language specifically identifies closed-cycle as a compliance alternative for the IM performance 

standards. EPA expects the Director would conclude that such a facility would not be subject to 

additional entrainment controls to meet BTA. 

EPA disagrees that impoundments with a specified retention time should be exempt from 

entrainment requirements. The commenter did not provide any data supporting the suggestion of 

7 days retention time. The retention time is the volume of the aeration tank divided by the 

influent flow rate. Thus even a 100 million gallon pond would still withdraw 14 mgd. The rule 

does not categorically exclude from entrainment requirements a facility with an impoundment 

has a retention time of 7 days or more, requiring that the Director address entrainment by a sitespecific assessment of entrainment impacts. In this assessment, the Director may potentially 

consider retention time to the extent retention time affects entrainment impacts. 

With regard to makeup water, such withdrawals can be significant. U.S. Energy Information 

Administration (EIA) data for 2010 shows 110 power plants (12 percent of all plants) use 

impoundments (U.S. DOE, 2012). About 50 of these plants operated in once through mode and 

60 used a closed-cycle mode. EPA also found in site visits that facilities with wet cooling towers 

did not operate the towers to minimize the withdrawal of makeup water. Therefore, in order for 

any given closed-cycle system to quality as a “closed-cycle recirculating system,” the final rule 

requires that the Director determine whether any specific impoundment, cooling tower, or other 

closed-cycle recirculating system, is properly operated and thus meets the definition of a CCRS 

under the rule. In addition, the states retain the ability to address local water issues. Finally, 

blowdown is included in the definition of a closed-cycle recirculating system to reflect the 

efficient use of cooling towers as part of the recirculating cooling system. EPA notes that the 

definition of a closed-cycle recirculating system in the preamble provides examples of proper 

operation, including flow reduction observed at power plants with well-operated cooling towers, 

as well as levels of the cycle of concentration found at manufacturing facilities with welloperated towers. These parameters generally represent minimized makeup and blowdown, with 

slightly different values for fresh and salt water sources of makeup water. 

Flow Thresholds

Two MGD Applicability Threshold

Approach

Some commenters questioned EPA’s approach in determining the applicability of the rule. Some 

commenters indicated that facilities below the 2 mgd threshold should not be subject to any 

requirements or, alternatively, EPA should use a presumption of no requirements if below this 

threshold except for exceptional circumstances. Some suggested that if a facility is below 2 mgd, 

EPA should allow states to determine that no impingement mortality or entrainment mortality 

controls are needed. Some argued that for otherwise exempt CWISs, only BPJ-based 

requirements should apply when AEI is evident or highly likely. On the other hand, comments 

Essay 14 62 
on behalf of a large umbrella group of environmental organizations supported the 2 mgd 

threshold because these facilities cause AEI and 2 mgd is consistent with Phase I. This 

commenter further suggested that if small facilities warranted different requirements, then the 

EPA should develop them rather than rely on establishment of BPJ controls for these facilities. 

Some commenters stated that 316(b) requires adverse impact and, lacking data for facilities with 

flow under 100 mgd, EPA has no authority to apply the rule to facilities with what the 

commenter’s viewed as de minimis impacts. Some commenters suggested that EPA should use a 

presumption that AIF of 125 mgd or below reflects BTA and that further reductions do not 

justify the costs. Commenters also suggested that closed-cycle facilities should not be subject to 

additional requirements, and that EPA should also exempt short term withdrawals. 

Facilities that withdraw 2 mgd or less are not subject to the national uniform standards for 

impingement and entrainment of this rule but, pursuant to this rule and section 316(b) of the 

CWA, remain subject to section 316(b) requirements determined on a case-by-case, best 

professional judgment, basis. The commenters did not provide any data showing any facilities 

smaller than 2 mgd have zero levels of impingement and entrainment. Therefore there is no 

record basis upon which to conclude that there is no potential for adverse environmental impact. 

Accordingly, EPA disagrees that any facilities should be exempt from section 316(b). 

The use of BPJ is a standard approach for determining technology-based requirements under the 

NPDES program in the absence of national standards. Such case-by case determinations allow 

any requirements to reflect the impacts associated with a facility and the CWIS technologies 

available. EPA has established in the record for this rule and prior 316(b) rules that CWISs result 

in a range of adverse environmental impacts including impingement and entrainment. The 

Second Circuit has found both EPA’s approach to AEI and EPA’s use of BPJ similar to this rule 

to be reasonable (e.g., See, Riverkeeper, Inc. v EPA, 358 F.3d 174 (2nd Cir. 2004)). 

EPA does not agree that all facilities below 100 mgd have de minimis impacts and can be 

excluded from the rule. Commenters did not provide any data showing any facilities with zero 

levels of impingement and entrainment. EPA further notes the commenter has provided no data 

to support the assertion that any levels of impingement and entrainment at such facilities have de 

minimis impacts. The record for this proceeding shows that there are identified studies 

impingement mortality and entrainment impacts associated with facilities, including those under 

100 mgd. EPA’s record indicates that the use of CWISs result in a range of adverse impacts 

including impingement and entrainment and that these impacts can and do occur at a range of 

flows based on a variety of factors (location, waterbody type, CWIS design, CWIS technology, 

seasonal factors, etc.). Thus, for the reasons discussed in the preamble, EPA has maintained the 

applicability threshold at greater than 2 mgd DIF. To address the range of impacts posed by 

different size and types of facilities subject to section 316(b) EPA has included considerable 

flexibility in the rule. 

EPA has explained in the preamble why the rule uses greater than 2 mgd DIF as the applicability 

threshold as opposed to using an alternative such as AIF of 125 mgd. As indicated in the 

preamble, the threshold in the final rule ensures that the users of cooling water causing the most 

adverse environmental impact will be subject to the rule. 

Essay 14 63 
Under this rule, and as discussed above, EPA expects that facilities with properly operated 

closed-cycle recirculating systems generally will not be subject to additional impingement and 

entrainment requirements. 

As for short term withdrawals, the final rule does not exempt short term withdrawals. The 2 mgd 

threshold for the design intake flow shows that the facility has the potential for significant 

withdrawals. Therefore facilities designed above this design threshold and use at least 25 percent 

of the water withdrawn for cooling are subject to the final rule requirements. The rule addresses 

short term withdrawals and intermittent withdraws by a compliance alternative at § 125.94(c)(6) 

that allows a facility to demonstrate credit for flow reductions. 

Certain commenters argued that including small systems and applying one set of requirements 

tailored to large systems to all systems will over-regulate small systems and impose undue 

burdens for limited environmental gain. These commenters disagreed with a one size fits all 

approach and suggested that EPA should set different categories of applicability that reflect 

potential impacts. 

EPA disagrees that 2 mgd is a small facility. For perspective, it would take four typical Olympic 

size swimming pools to provide two million gallons. EPA has addressed the concern over 

uniform requirements in the rule through flexible requirements including seven compliance 

alternatives, rather than the applicability provisions of the rule. The final rule’s multiple 

compliance alternatives (including use of a system of technologies) for addressing impingement 

mortality, and further provides for site-specific determination of requirements for addressing 

entrainment (for other than new units). These provisions, which reflect the data evaluated by 

EPA, do not mandate one set of requirements for all facilities and are capable of reflecting the 

setting and the impacts posed by different facilities. 

Some commenters asserted that limited use emergency or special circumstance intakes should 

not be subject to regulation because costs vastly outweigh benefits. Commenters noted that 

secondary sources of makeup water used not more than 30 days per year should be exempt. They 

also suggested that emergency flows should not be considered in determining applicability (e.g., 

2 mgd). 

The commenter did not provide data or identify special circumstance intakes. However, the 

commenter appears to be confused by the definitions in the rule. The definition of Design Intake 

Flow does not include emergency purposes, fire suppression, and back up pumps (redundant 

pumps). Intermittently used intakes are discussed above. The commenter did not provide data 

showing why secondary sources of makeup water should be exempt. As noted above, there is no 

record showing zero levels of impingement and entrainment. Thus there is the potential for 

adverse environmental impact, and EPA disagrees that secondary sources of makeup water 

should be exempt. 

In the final rule EPA has provided that DIF does not include values associated with emergency 

and fire suppression capacity or redundant pumps (i.e., back-up pumps). 

One state (LA) indicated that it has ample surface water and commented that the proposed rule 

does not promote the use of surface water. EPA agrees with the comment. As noted above, there 

Essay 14 64 
is no record showing zero levels of impingement and entrainment. Thus there is the potential for 

adverse environmental impact, and EPA disagrees that surface water use should be promoted. 

AIF	 	 	 	 	 as Metric for Threshold

Several commenters supported the use of AIF in determining applicability of the rule. 

Commenters stated that AIF should be used for the applicability threshold since AIF correlates 

with environmental impact. Commenters indicated that the use of DIF is unduly burdensome 

(i.e., costly, with disproportionate impact) for smaller facilities with minimal flows and has 

limited impact since the use of DIF will apply the same requirements to large and small facilities. 

Commenters also pointed out that DIF penalizes facilities that have installed more efficient units 

or modifications that require less water, whereas, AIF promotes conservation. Commenters also 

indicated that DIF may be difficult to determine for existing and older facilities and may be 

significantly greater than the current AIF due to changes over time, particularly in manufacturing 

processes. Some maintained that applicability DIF should focus on current operation and 

capabilities, not original design or special circumstances. EPA could determine AIF based on 

flow data (based on one or a few flow monitors) and this approach provides more clarity since 

existing facilities are likely have many years of flow data. DIF may result in inconsistency 

because of different methods for determining DIF (i.e., DIF is difficult to determine). Some 

commenters asserted that it is inconsistent to base impingement mortality on DIF and 

entrainment mortality on AIF. Some commenters suggested that EPA use AIF that corresponds 

to 50 mgd DIF. Some argued that AIF encourages conservation and added that if DIF is used 

EPA should allow an estimate to be based on empirical data. 

EPA has used DIF in the applicability threshold for the reasons stated in the preamble to the final 

rule. This approach was also adopted in the Phase I and Phase II rules. DIF reflects a reasonably 

well-defined criterion that does not vary widely over time and that reflects the potential for 

adverse environmental impacts. AIF can vary significantly over time and therefore is not ideal 

for determining rule applicability. Even if EPA had used AIF, it does not necessarily follow that 

EPA would have developed tiered levels of requirements based on different AIF thresholds. EPA 

disagrees with the comment that DIF is more burdensome than AIF; DIF is a fixed parameter 

that need be determined only once for purposes of rule applicability, whereas AIF must be 

frequently measured and reassessed. EPA’s use of AIF in some parts of the rule may result in an 

incentive for some facilities to withdraw less cooling water, and EPA encourages such an 

outcome. Further, the final rule includes incentives for water reuse in lieu of water withdrawal. 

To address comments concerning original DIF or a design basis that is outdated, in the final rule 

EPA has provided an opportunity in described circumstances for a facility to use an adjusted 

DIF. The revised DIF would reflect permanent changes to the maximum capabilities of the 

cooling water intake system to withdraw cooling water. This allows facilities that have made 

such changes credit for their actions. These circumstances may include removal of pumps 

permanently from service, flow limit devices (installed devices that act to restrict flow below 

design flows), and physical limitations on intake flow that result from piping restrictions. With 

regard to the ability to determine DIF, EPA maintains that existing facilities will have the 

information needed to determine the appropriate DIF. If changes have occurred, appropriate 

adjustments, as described above, can be made in that determination. The final rule requires the 

Essay 14 65 
development of detailed information on entrainment in the permit application for facilities above 

the 125 mgd AIF threshold. The use of AIF rather than DIF is appropriate for this requirement 

because, as EPA has consistently indicated, entrainment impacts are generally correlated with 

intake flow. Further, in the final rule EPA has defined AIF as the average flow including a 

facility’s days of zero flow. 

DIF	 	 	 	 	 as Metric for Threshold

Other commenters supported the use of DIF in the applicability threshold for the rule or 

supported the use of DIF as the maximum volume of water a facility can withdraw. Some 

commenters suggested that EPA clarify the definition of DIF to allow for limiting flow in the 

NPDES permit. Still others supported the use of DIF for applicability and AIF for entrainment 

study required in the application requirements for 316(b) NPDES permits. 

Some commenters suggested that the use of DIF for applicability should consider legally 

enforceable limitations on flow, including permit conditions. They asserted that this (activity 

constraints) is done under the Clean Air Act’s Prevention of Significant (CAA/ PSD) program 

and creates an incentive to voluntarily reduce flows. These commenters suggested that EPA 

change the DIF definition to allow enforceable limits or legal controls on AIF (and make the rule 

not applicable if below 2 mgd). Other commenters asserted that DIF really should be “maximum 

intake flow” or “intake flow capacity” and should reflect all physical, structural, operational and 

engineering characteristics of the facility’s cooling water system, as well as any legally binding 

limits on water withdrawal, use or discharge. 

Some suggested that EPA give credit to a facility for operating below its DIF. Some comments 

went on to suggest that EPA define DIF so as to not penalize facilities for having more capacity 

than is needed or used based on good engineering practice. Others commented that use of DIF is 

acceptable provided facilities do not get credit for fictional flow reductions. Some suggested that 

the DIF should reflect the maximum amount of water that can be withdrawn by the plant. Some 

commenters suggested that EPA clarify whether there is a difference between a unit closure and 

a unit retirement, and whether a pump permanently removed from service is flow reduction or 

warrants an adjustment in the DIF. Some commenters suggested that, with regard to the 2 mgd 

applicability threshold, EPA must specify the timeframe for measuring DIF. 

As discussed on the preamble, EPA has used “design intake flow” because it is an established and 

reasonably consistent metric that reflects the potential for AEI. EPA based its threshold for 

applicability of both the Phase I and development of the Phase II and Phase III rules on DIF. EPA 

has used the term DIF because it is a commonly used term with a clear meaning. The DIF does not 

need additional time frames because a permit is applicable for at most 5 years, and there is no 

evidence suggesting cooling water intakes are modified as frequently. The final rule’s definition of 

DIF has been implemented for over 10 years and is understandable. This definition addresses those 

factors that affect the maximum rate of flow the facility is physically capable of withdrawing. 

The final rule does provide that a facility’s DIF may be adjusted to reflect permanent changes to 

the maximum capabilities of the cooling water intake system to withdraw cooling water, 

including pumps permanently removed from service, flow limit devices, and physical limitations 

of the piping. Consistent with this provision, any closure or retirement would have to result in 

Essay 14 66 
permanent changes to a facility’s DIF for it to warrant credit. DIF flow information must be 

submitted as part of permitting and this information, and the ability to obtain additional 

information, should prevent credit for fictional flow reductions. Finally, together the DIF 

definition and 2 mgd threshold sufficiently specify the timeframe for DIF. 

However, design intake flow as defined in this rule does not reflect legally enforceable limits on 

flow since such flows can change and EPA has some concern regarding establishing permit 

limits that could unduly hinder facility operations without a permit reopening or renewal. For 

purposes of applicability, the rule does not provide a credit to a facility for operating below its 

design capacity, because all facilities operate at an AIF below their DIF. EPA’s record shows 

facilities operate, on average, with an AIF of half of their DIF. This does not necessarily 

represent any reductions in flow, it merely describes the operation of a CIWS on an annual 

average basis. Credit for actual flow reductions is provided under the BTA requirements. 

Basis	 	 	 	 	 for 2 MGD Threshold

Commenters challenged EPA’s basis for the 2 mgd threshold. Some commenters asked for 

additional justification for the 2 mgd threshold. Some commenters did not understand that 

today’s final rule considers both the Phase II and Phase III rules, instead commenting that this is 

a revised Phase II rule that covers more facilities than the 2004 Phase II rule. Some argued that 

studies from large power generating facilities cannot be used to justify the 2 mgd threshold for 

industrial facilities. Some argued that the 2 mgd DIF threshold is arbitrary because it fails to 

consider site-specific factors and different levels of impact. For example, some commenters 

argued that the threshold was arbitrarily too low because it could affect a facility that withdraws 

0.000009 percent of Mississippi’s 7Q10. Others noted that the effective threshold is 0.5 mgd (25 

percent of 2 mgd), so the rule would cover more than 99.7 percent of cooling water intake flow 

as asserted and maintained that this is not justified by any technical or scientific analysis. 

Commenters argued that the 2 mgd threshold would impact many small facilities including small 

businesses and that small facilities should not be subject to all the controls required for larger 

facilities. Some commenters suggested that if the threshold is not 50 mgd, it should be 5 mgd at a 

minimum. Others suggested that if the threshold is not 50 mgd DIF, then EPA should use AIF 

since AIF reflects impacts and the actual use of intake. Some suggested that EPA use an AIF 

threshold of 50 mgd, while some would limit this to impingement mortality only. Some 

commenters indicated that facilities below 50 mgd should be addressed using BPJ, whereas 

others suggested that such facilities should not be subject to the rule at all. Some argued that 

EPA should use 125 mgd to address 90 percent of cooling water flow and lower the cost of the 

rule. Some commenters indicated the basis for 125 mgd AIF monitoring and reporting threshold 

was unclear. Others noted that 2 mgd will capture some facilities that already have CCRS. 

As previously discussed, all water withdraws for cooling water result in the potential for 

impingement and entrainment. The 2 mgd threshold was chosen because this threshold addresses 

99.7 percent of the total flow and 62 percent of all in-scope facilities. EPA estimates that 58 

percent of the manufacturers, 70 percent of the non-utilities, and 100 percent of the utilities will 

be regulated at the 2 mgd threshold. The final rule uses greater than 2 mgd as one of the 

applicability criteria to be consistent with the Phase I rule, and to ensure that the largest users of 

cooling water are subject to the rule. Section 316(b) of the CWA addresses cooling water intake 

Essay 14 67 
structures generally, and EPA has examined the cooling water intake flow and the facilities 

captured in the context of the section 316(b) requirements. As EPA has discussed in the 

preamble and in this essay, CWIS technologies and the nature of associated impacts do not vary 

substantially between utility and industrial applications. Further, EPA agrees that adverse 

impacts can and do occur at various flows. Further, the less than 50 mgd facilities are twice as 

likely now to have no controls in place for impingement or entrainment as are the greater than 50 

mgd facilities. The EPA has structured this final rule to be broadly applicable and to address 

different facilities and physical settings within the rule. 

EPA disagrees that low flow correlates to small business. Nothing about the definition of small 

business includes cooling water withdraws. Further, there is no correlation between small 

businesses and facilities with the lowest flows. For example, while there are 34 facilities that are 

small businesses and withdraw less than 10 mgd, there are another 35 facilities that are small 

businesses and withdraw more than 50 mgd. None of the commenters alternative thresholds 

including 2 mgd, 10 mgd, 20 mgd, 25 mgd, and 50 mgd are supported by data, and EPA has no 

technical reason on which to base a different threshold. See EA for more information. EPA 

agrees that 2 mgd threshold will capture some facilities that already have CCRS. EPA’s record 

shows that most facilities are in the less than 50 mgd category because they already have closedcycle cooling. According to EPA’s technical survey data from 2001, 51 percent of facilities with 

DIF below 50 mgd have closed-cycle cooling, and 33 percent of manufacturers with DIF below 

50 mgd have closed-cycle cooling. See the TDD for more information. EPA notes the final rule 

streamlines the permit application process for facilities with closed-cycle. 

The EPA disagrees that power plant intakes cannot be compared to manufacturing intakes. 

Intakes at power plants and manufacturers exist in a variety of sizes, use the same intake types 

and locations, and use the same technologies. At many manufacturing facilities, cooling water is 

withdrawn primarily or exclusively for power production. These intakes functions exactly like a 

power plant intake. EPA finds that there are no significant differences in CWIS or technologies 

between manufacturers and power generators. The technologies are available and feasible for all 

intake structures. See TDD Chapter 4 for more information. With respect to environmental 

impacts, aquatic organisms cannot distinguish what is behind an intake; there is no difference to 

a fish whether the user of the cooling water behind the screen is a power plant or a paper mill. In 

many cases, power plant intakes and manufacturing facility intakes occur in close proximity on 

the same source waterbody; see EBA for more information. Financial impacts of the final rule 

were considered separately for each industry; see the EA for more information. 

EPA agrees that small withdrawal may pose a significant adverse environmental impact, both 

when the source waterbody has a low flow and when there are cumulative withdraws (multiple 

users) of the same reach of a source waterbody. At least 14 percent of manufacturers below 50 

mgd withdraw more than 5 percent of the mean annual flow of the fresh water sources on which 

they are located (based on unweighted data from surveyed facilities; actual number would be 

higher when all in-scope facility locations are considered). Furthermore, facilities in aggregate 

may withdraw greater than 100 percent of the river on which they are located. For example, all 

facilities combined on the upper reaches of the Monangahela River withdraw 526 percent of the 

mean annual flow of the river, and the facilities on the lower reach withdraw an additional 474 

percent of the mean annual flow. The record further shows cumulative impacts of facilities with 

DIF below 50 mgd are significant in most of the U.S.; see GIS mapping in the EBA. The 

Essay 14 68 
analysis shows at least 54 percent of withdrawals by just those facilities with DIF below 50 mgd 

are cumulative withdrawals, i.e., there are withdrawals by more than one facility on the same 

river segment. For example, 5 known facilities with DIF below 50 mgd withdraw 45 percent of 

the mean annual flow of the Delaware River. The potential impacts are greater when facilities 

with large flow withdraws are included in the analysis. For example, there are 8 known facilities 

with DIF below 50 mgd that withdraw 3 percent of the mean annual flow of the Columbia River. 

This increases to 8 percent of the river MAF when the large flow facilities (those greater than 50 

mgd) are included. For all of these reasons, no facilities in scope of the rule are exempt from IM 

or E requirements to minimize adverse environmental impacts. 

EPA does not agree that the intake flow threshold in the applicability portion of this rule must be 

based on prior determinations of the degree of environmental impact caused by a specific facility 

or specific cooling water intake structure. Further, EPA disagrees that EPA has no data for lower 

flow facilities demonstrating an adverse environmental impact. Sizeable numbers of fish 

impinged by lower flow facilities, including more than 40 studies from less than 50 mgd 

facilities. Greater than 82 percent of impinged fish mortality would be prevented by this rule. 

As discussed above, lower intake flow does not mean low impact to the source water, and 

cumulative withdrawals can cause compound impacts. Section 316(b) applies to any facility that 

uses a cooling water intake structure and is a point source subject to standards imposed under 

CWA section 301 or 306. EPA has included a flow threshold to provide some reasonable limit 

on the scope of the national requirements imposed under today’s rule. The Agency has 

concluded that those existing facilities having withdrawals that are at or below a two mgd 

threshold are generally the smaller intakes that may face issues of cost effectiveness, feasibility, 

and achievability and are therefore more appropriately addressed by establishing BPJ section 

316(b) controls as provided for in 40 CFR Part 125. 

The impingement and entrainment provisions of this rule are flexible and thus can be effectively 

applied to address different types and sizes of facilities and different facility settings. While 25 

percent of 2 mgd is 0.5 mgd, this does not mean that final rule would apply to a facility with an 

intake flow threshold of 0.5 mgd. The rule only applies to facilities with an intake flow threshold 

of greater than 2 mgd. A facility with a lesser flow all of which was used for cooling water 

would still not be subject to the categorical requirements of this rule. In addition, impacts 

generally are associated with the total intake flow of a CWIS. EPA considered alternative 

thresholds as part of rulemaking development and is using the 2 mgd threshold for the reasons 

discussed above and in the final rule preamble. As explained in the preamble, the 125 mgd AIF 

threshold focuses on facilities with higher flow since such facilities result in greater potential for 

adverse impacts, especially entrainment impacts. EPA data indicate that this threshold captures a 

significant percentage of cooling water flow associated with adverse effects to the aquatic 

ecosystem while it reduces the number of facilities subject to the more detailed permit 

applications requirements for entrainment characterization. EPA expects that, in most instances, 

facilities that already have CCRS are unlikely to be subject to further requirements. 

Burden/Cost

Commenters also express concern regarding the cost of the rule. Some commenters questioned 

EPA’s basis for the 2 mgd threshold and suggested that the cost and benefit analysis supports a 

Essay 14 69 
different threshold. Commenters asserted that a 50 mgd threshold (Option 4) is more appropriate 

and supported by the benefits analysis (the cost of the rule would be much lower; the benefits 

would only be slightly lower; 50 mgd captures a significant percentage of the cooling water flow 

yet it omits smaller facilities, resulting in a justification based on a cost-benefit basis). Some 

commenters pointed to Phase III, stating that the costs were not justified. Some pointed out that 

increasing the threshold from 2 to 50 mgd will reduce the proposed rule costs by $57 million and 

only reduce benefits by $1 million. 

Some commenters stated that lower thresholds will exponentially increase the burden on the state 

(affecting 30 percent of majors and 3 percent of minor permitted industrial facilities). They 

questioned whether meaningful environmental benefits will result from the rule. Other argued 

that at 2 mgd the costs of the rule are wholly disproportionate to its benefits. Some argued that 

EPA has underestimated the true costs of various control technologies by a factor of 2 by not 

considering facility modifications and ancillary equipment, and therefore that EPA should adopt 

proposed Option 4. 

Although EPA clearly may consider costs and benefits in establishing 316(b) standards, as 

discussed in the preamble to the final rule, EPA’s determination of the BTA standards is also 

based on factors other than costs and the relationship of costs to benefits (see the discussion of 

legal authority in the preamble). Furthermore, EPA retains discretion with regard to how to 

balance these factors. As such, selection of the applicability threshold is not a simple cost-benefit 

calculation. In addition, limitations of the cost and benefit analyses should be acknowledged. 

One limitation on the use of cost-benefit is the fact that, as discussed in the preamble, relatively 

few benefits associated with this rule have been or can easily be quantified and monetized. To 

the extent commenters believe cost-benefit analysis should only reflect monetized benefits, EPA 

disagrees. 

With respect to comments comparing this rule to Phase II and Phase III, the EPA notes the Phase 

III proposal option is no longer relevant. The Phase III rule co-proposed a 50 mgd threshold 

assuming full implementation of the Phase II rule. The Phase III rule was based on those I&E 

requirements consisting of percent reductions over a baseline. Therefore the Phase III rule would 

have imposed E requirements on facilities of all flow thresholds, whereas this final rule does not. 

A comparison between the Phase III rule and this rule is therefore not meaningful. Further, a 

Phase III rule with similar requirements to Phase II would have cost $216 million annually 

($2012 using ENR index) for 603 facilities, including 91 small businesses. Today’s revised 

section 316(b) rule provides a flexible approach for IM compliance, and does not establish 

uniform national E technology requirements. 

Financial stress has been further mitigated by a $180 million reduction in costs over the Phase III 

rule cost for lower flow facilities. However, because the technical basis for this rule is different 

than the technology basis for Phase II and Phase III, the costs are not directly comparable to this 

final rule. The costs for the proposed rule revisions (including the reduced biological monitoring 

requirements for existing facilities between 2 and 50 mgd) are $22 million for 476 facilities 

below 50 mgd; about $295 million for the 589 facilities above 50 mgd (i.e., about 7 percent of 

total rule costs are cost for lower flow facilities). The flexibilities of the final rule will further 

reduce the compliance costs; see Essay 21 regarding EPA’s overestimation of rule costs. This 

results in EPA’s finding that there are no manufacturing facilities with a cost-to-revenue ratio of 

Essay 14 70 
3 percent, and one facility with a cost-to-revenue ratio exceeding 1 percent, all under a 

conservative assumption of zero cost pass-through to the consumer. See EPA’s composite 

findings regarding no SISNOSE in the preamble. Electricity sector revenues exceed $126 billion, 

and the final rule cost is less than 0.1 percent of revenues. These costs for lower flow facilities 

are too small to affect costs of power or household utility bills. In summary, because there are 

affordable, available, and feasible technologies for impingement, EPA does not have an 

economic rationale for excluding low flow facilities from the national uniform requirements. 

With respect to small businesses specifically, the final rule adopts two recommendations of the 

SBAR panel: (i) clarification, consolidation, or simplification of compliance and reporting 

requirements under the rule, and (ii) the use of performance rather than design standards. 

With regard to states, delegated states are currently responsible for issuing permits including 

316(b) requirements to existing facilities that use CWISs. Under this rule states remain 

responsible for implementing 316(b) conditions in permits (both categorical requirements and 

those based on BPJ). With or without a rule, permits must address cooling water intake 

structures. The final rule establishes a procedure for collecting information, conducting studies, 

and evaluating alternative technologies. The final reports for the suite of entrainment studies 

required by facilities with an AIF greater than 125 mgd must be peer-reviewed, alleviating 

concerns that the public and permit authorities won’t have accurate and reliable information to 

inform decision-making. Therefore this rule does not dramatically increase the burden on states 

beyond their current responsibility. In many cases, the rule is expected to reduce the burden on 

states as the states will no longer have to determine BTA on a case-by-case basis. The rule 

provides a clear framework for issuing NPDES permits that include 316(b) permit conditions. 

For the same reasons, if EPA were to adopt commenter suggestions about higher thresholds, 

Directors would have an increased burden in determining site-specific IM requirements. Based 

on the Phase II ICR costs for permit application and studies ($395k to $679k per facility initial 

permit application, plus $7k annual reporting and monitoring), the submission of basic 

characterization studies and permit application materials upon which site-specific impingement 

requirements would cost the 603 facilities below 50 mgd an aggregate $69 million per year 

($2012). This is approximately twice the cost of the studies plus technologies for meeting the IM 

requirements of this final rule. Thus, EPA finds it is more cost-effective to set uniform standards 

for impingement than to utilize BPJ. In other words, the revised rule is more cost-effective than 

BPJ decision-making for IM at existing facilities below 50 mgd. EPA notes the same conclusion 

does not hold true for entrainment. 

With regard to the relationship of estimated costs to benefits, EPA did consider the cost and 

benefit data available in the development of this rule. EPA has developed a final rule based on all 

relevant factors, but its BTA determinations hinged on factors other than costs and benefits. 

EPA’s analysis does indicate that the benefits of the final rule justify its costs. Moreover, the 

significant flexibility built into the rule allows it to be implemented in a cost-effective manner. 

Use of AIF for Entrainment Characterization Study

Several commenters supported the use of AIF for the 125 mgd threshold for the permit 

application requirement to provide entrainment characterization information because AIF better 

reflects potential CWIS impacts. Some support 125 AIF but assert that the rule should not 

Essay 14 71 
require entrainment mortality controls for facilities with flows less than 125 AIF and observe that 

the use of 125 AIF will address 90 percent of flows. Some expressed concern that, as proposed, 

facilities under 125 AIF will have to submit expensive engineering and cost studies and EPA has 

not considered these costs for non-primary manufacturing facilities. 

Some commenters suggested that EPA clarify that the 125 mgd AIF threshold for the 

Entrainment Characterization Study allows for averaging flow over the whole year, including 

periods of zero flow. This is important for peaking and load-following facilities, which have low 

average flow and very limited impact. Some suggested that EPA should specify how AIF would 

be calculated for facilities with multiple intakes. 

Other commenters opposed the use of AIF for the Entrainment Characterization Study and 

indicated that decision-makers need to know the potential for adverse environmental impact 

(which is better reflected in DIF), and could also consider AIF alongside the DIF. Some 

commenters wanted EPA to reduce 125 mgd AIF to 20 mgd DIF for industrial facilities required 

to meet entrainment mortality requirements and maintained that the time of year and life history 

determines impacts. Some commenters indicated that there is no statistical basis for entrainment 

requirements based on AIF and DIF. One commenter asked EPA to use 200 AIF under Option 4. 

Finally, some commenters asked that EPA clarify that only facilities greater than 125 mgd are 

subject to entrainment mortality requirements. 

The final rule provides that for existing facilities the entrainment requirements are to be 

determined on a case-by-case basis. Such requirements are applicable to all in-scope facilities 

(including those with intake flows at or below 125 AIF). Under the final rule, facilities with an 

AIF at or below 125 AIF will only submit those entrainment characterization studies and data as 

requested by the Director. The full entrainment characterization studies are required of all 

facilities above 125 AIF. EPA has clarified in the rule that AIF reflects an average annual flow 

that considers days of zero flow. DIF and AIF for a facility with multiple in-scope intakes is 

based on the total flows of the intakes as defined in the rule, although DIF does not include flows 

associated with emergency and fire suppression capacity. EPA has specified AIF in the final rule 

for the Entrainment Characterization Study for the reasons specified in the preamble. The 

Entrainment Characterization Study is designed to reflect factors relevant to entrainment 

including time of year and life history. The permit application includes DIF, thus the Director 

will already have the DIF and AIF information together. As discussed above, the record shows 

that there are identified studies impingement mortality and entrainment impacts associated with 

facilities, including those under 100 mgd, thus EPA disagrees that only facilities greater than 125 

mgd should be subject to entrainment mortality requirements. 

AIF is more appropriate than DIF in this role since case-by-case requirements can be developed 

to address known actual impacts, whereas it would be more difficult to develop appropriate 

controls based on projected impacts and such controls may overregulate actual impacts. In 

addition, AIF reflects flow over multiple years so it should be representative of typical operating 

conditions. Under the final rule permit conditions, including entrainment requirements should be 

reassessed each permit term based on current permit application information. 

Essay 14 72 
Applicability of Rule to Offshore Oil and Gas Facilities, Seafood Processing Vessels or

LNG Import Terminals

Some commenters supported the determination of section 316(b) requirements at existing 

offshore oil and gas facilities on a BPJ basis. Other commenters maintained that offshore 

facilities should be subject to categorical standards that minimize AEI, and suggested that EPA 

should clarify whether it considered variable speed pumps and operational changes for such 

facilities. Commenters also suggested that EPA should clarify that § 125.91(d) provides that only 

ocean-going vessels are exempt from the categorical provisions of the rule. Still others argued 

that only offshore (ocean going) seafood processing vessels are exempt from categorical 

standards. 

Some commenters argued that the proposed definition of new CWIS (i.e., the date used to 

distinguish existing facilities from new facilities) conflicts with the definition of existing 

offshore oil and gas facility adopted in Phase III. The requirements applicable to facilities 

between January 17, 2002 (the date adopted in Phase I and proposed to delineate new versus 

existing facilities) and July 17, 2006 (the date established to define existing offshore oil and gas 

facilities in 40 CFR 125.33) conflict (or are ambiguous) and it is unclear whether Subpart J or N 

applies to offshore oil and gas facilities constructed between these two dates. The existing 

facility definition should include “(or July 17, 2006 for an offshore oil and gas extraction 

facility).” These commenters stated that EPA should retain the existing date (July, 17, 2006) for 

offshore facilities. Some commenters also asserted that visual or remote monitoring is 

problematic for offshore submerged CWISs, has no basis, and should be limited to once per year, 

an approach that has proven effective with effluent diffusers. 

EPA considered a variety of technologies available to existing offshore seafood processing 

facilities as part of the Phase III rulemaking. As discussed in the preamble, EPA did not identify 

technologies that were effective, broadly available, and did not interfere with the seaworthiness 

and safe operation of the facility. See in addition to this rule record the Phase III rule record, 

including the Phase III TDD. Such facilities were less likely to have space for redundant pumps 

or excess capacity. A variable speed pump it would be unlikely to achieve more than a five 

percent reduction in flow, and was rejected both as available, feasible, and as a most effective 

technology. Commenters did not suggest any operational changes available to an offshore 

facility. EPA has not identified any new information since the Phase III rulemaking to identify 

any available, feasible, and most effective technologies for existing offshore faculties. Therefore, 

any requirements for existing offshore faculties are best determined on a site-specific basis using 

BPJ. 

EPA also notes that existing facilities do not have the same opportunities as new facilities to 

install better performing equipment. This rule provides for requirements for existing offshore 

facilities based on BPJ and, thus, the Director can consider technologies that meet BPJ criteria 

(in contrast, on-shore existing facilities are subject to the uniform national rule requirements). 

The definitions that address existing offshore seafood processing facilities are sufficient to 

identify in-scope facilities. EPA has clarified the existing facility definition to be consistent with 

the provisions addressing existing offshore oil and gas facilities. With regard to visual or remote 

monitoring, these are established practices, yet because implementation can be challenging in 

Essay 14 73 
some situations, EPA has included some flexibility for the Director to modify these requirements 

where warranted. 

Definition and Applicability of New Unit

Commenters expressed views regarding the new unit definition and provisions in the rule. Some 

supported EPA’s definition of new unit and the new unit provisions. Some commenters want the 

new unit provision deleted. Some commenters suggested that EPA should clarify what 

constitutes a new unit at manufacturing facilities. They asserted that the definition of new unit is 

confusing and that it appears tailored to power plants, and asked if EPA could provide examples. 

Some noted that the rule does not define operating unit. Others pointed out that the term 

generation capacity is unclear, and could refer to intake structure flow or the capacity to produce 

a certain product. 

EPA has added some language in the definition of new unit that clarifies how this term could 

apply to manufacturers. EPA has not defined operating unit but has made additional efforts to 

make the definition of new unit clear. The final definition of new unit does not use the term 

generation capacity. 

Some commenters stated that EPA has failed to explain how the definition of new unit relates to 

applicability thresholds in rule. 

EPA disagrees with the comment. The rule makes it clear which facilities are in scope. A facility 

must be in-scope of this rule for the new unit definition to be potentially relevant. A new unit 

does not have a separate applicability threshold. The applicability of the requirements of the final 

rule to a new unit at an existing facility are determined by whether the existing facility uses a 

cooling water intake structure with a design intake flow greater than 2 mgd and not by the design 

intake flow of the new unit. 

Numerous commenters support not regulating rebuilt, replaced, upgraded or repowered facilities 

or elements of facilities as new units for the reasons stated by EPA. Some supported power plant 

upgrades and installation of replacement units as existing units. Some commenters argued that 

repowered and replacement units are not new and do not have lower capital costs. Some asserted 

that EPA should define repowering to include fuel conversions. Some commenters suggested 

that repowering and replacement involve limited reconfiguration and do not create opportunities 

for wholesale replacement of cooling systems and related equipment. Others noted that the 

existing definition of new units promotes upgrades that increase efficiency and a broader 

definition would hinder cleaner, more efficient technology. Some commenters observed that no 

baseline date has been set to define which retired units can be repowered or replaced. Some 

commenters argued that the rule should promote retiring older units and repowering with cleaner 

technologies, as well as allow for the use of existing capital intensive assets. 

EPA has included the new unit requirements in the final rule for the reasons discussed in the 

final rule preamble. The impingement and entrainment requirements specified apply to the intake 

flow serving the new unit only. EPA has not determined that fuel conversions provide the same 

opportunity to install CCRS as the addition of a new unit, and agrees with those commenters 

accordingly. The final rule definition of new unit does not specify a date to identify which units 

Essay 14 74 
can be repowered because identifying such a date is not necessary in the final definition. EPA 

supports the use of cleaner technologies but notes that this rule does not address power 

generating technologies, rather the rule addresses CWIS technologies. 

In contrast, some commenters asserted that EPA defines new unit too narrowly and that rebuilt, 

retrofitted, repowered or replaced units should be subject to the more stringent controls 

regardless of whether the unit or facility increases intake or generation capacity. Some suggested 

that any modifications (rebuild, repower, replacement) should require cooling towers. They 

asserted that many of the reasons that justify the use of closed-cycle cooling at new units apply 

to repowered or replaced units. Commenters from New York State indicated that New York 

State regulates repowered or replaced units as new, since to do otherwise would cause 

unnecessary harm to aquatic resources. The New York Department of Environmental 

Conservation recommended that EPA require all repowered and replaced industrial facilities 

with a DIF of 2 mgd or more to meet the standards of the Phase I rule since the rationale for that 

rule applies directly to such facilities. Similarly, The Connecticut Department of Energy and 

Environmental Protection suggested that the new unit definition should be broader, 

encompassing repowering, rebuilding or replacement, even if capacity is not increased, since 

these major modifications present an opportunity for a facility to evaluate and invest in effective 

technology in a cost-effective moment. Commenters also asserted that repowered, replaced and 

rebuilt facilities must be subject to the same closed-cycle cooling requirements as new units at 

existing facilities. One commenter stated that EPA should adopt the definition of new unit in the 

version of the proposed rule that was submitted to OMB shortly before proposal as the proposed 

definition of new unit and existing facility are problematic in that facilities expanding or 

upgrading are not required to use modern CWIS technology. These commenters stated that EPA 

does not provide justification for not treating replaced, repowered, or rebuilt facilities as new 

units. Some commenters suggested that new units should include physical changes to an intake 

structure that materially increases the design flow rate and EPA should not include the 

replacement of components that do not do so. Some commenters asserted that EPA’s definition 

of new unit would create a huge loophole. 

The final rule does not require CCRS for existing units at existing facilities for the reasons 

discussed in the final rule preamble. It does provide for CCRS for new units based, as discussed 

in greater detail in the preamble, on the unique situation the addition of new units at a facility 

provides. This approach is consistent with the efficacy, feasibility, cost and other data available 

to EPA, as well as with the Phase I rule. EPA’s definition of new unit in the final rule is 

consistent with this approach. In addition, this rule does not restrict states from imposing more 

stringent requirements pursuant to state law. EPA does not agree that the definition of new unit 

creates a loophole because, under the final rule and the new facility rule, a facility will be subject 

to regulation either as a new facility, existing facility, or a new unit at existing facility. Any 

existing facility not subject to this rule, as noted, will continue to be subject to section 316(b) 

requirement established on a BPJ basis pursuant to 40 CFR 125.91. 

Some commenters asserted that EPA’s approach to new units is not authorized (the CWA 

addresses intakes, not units), is arbitrary (in the Phase II rule EPA rejected addressing new units 

at existing facilities and no new justification is provided for reversing that decision, only 

unsupported assertions), is unclear (it is unclear with regard to when manufacturing units are 

replacement versus increased capacity, and whether the new unit must meet a DIF threshold) 

Essay 14 75 
and, as a result, is unworkable. Commenters stated that the new unit provisions are so unclear 

that EPA needs to re-propose them. Commenters asserted that the definition of “replacement 

unit” needs to be clarified. Some commenters stated that the assertion that the capitol costs for 

closed-cycle at new units are lower than the capitol costs for once through cooling is not 

credible, and that new units require the same equipment, plus cooling towers. Other commenters 

argued that limited land availability is an issue for new units required to install closed-cycle 

cooling. Some maintained that EPA has not justified the conclusion that closed-cycle cooling is 

BTA for new units. These commenters asserted that existing facilities installing new units have 

less space than other facilities, issues such as drift still are problematic, and it is EPA speculation 

that existing facilities have the option to reduce water usage elsewhere (modern manufacturing 

facilities have reduced water use significantly). Commenters also argued that EPA’s decision to 

define only units added to increase capacity is OMB driven, contrary to EPA technical experts, 

irrational, arbitrary and capricious. 

EPA has explained its basis for the new unit provisions and definition in the preamble to the final 

rule. As indicated in the preamble, EPA has compiled and assessed additional data since 

publishing the Phase II rule and these data, including engineering and costs analyses, support 

EPA’s approach in the final rule. Based on the final rule record, EPA maintains that exiting 

facilities have greater flexibility in configuring new units and associated cooling than in altering 

aspects of existing units, and that repowering which constitutes installation of a new unit creates 

engineering opportunities to install closed-cycle cooling. As EPA has stated above, the final rule 

definition has been clarified and includes language that addresses manufacturers. It does not use 

the term replacement unit. 

Some commenters asserted that, for new units, the rule should focus on the design of the 

condenser cooling system being consistent with closed-cycle cooling. EPA agrees with the 

comment, and has revised the final rule requirements and definition to achieve a similar result. 

Some commenters indicated that a new unit cannot determine the cost of compliance until after 

the facility is constructed. EPA disagrees with the comment. EPA’s record includes costs for a 

retrofit. Retrofits are more difficult to assess than new construction. Therefore EPA maintains 

that reasonable cost estimates can be developed prior to construction. 

Some commenters noted that when submitting a permit application for a new unit, baseline 

entrainment densities at the existing facility could be exceeded due to natural population 

fluctuations. EPA agrees that source water characterization can change with season, diel, 

weather, and further can change over time. Accordingly, EPA requires that the characterization 

be updated with the application for permit renewals, and requires biological studies be conducted 

over sufficiently long periods to characterize such fluctuations. 

Some commenters suggested eliminating the new unit provision and addressing new additional 

units consistent with Phase I requirements. EPA disagrees with the comment. This rule does not 

alter the Phase I rule provisions. This rule has been developed to be consistent with the Phase I 

rule while addressing exiting facilities. The Phase I rule was not developed to address new units 

at existing facilities and, thus, this rule is the appropriate mechanism for doing so. 

Essay 14 76 
Some commenters asserted that the new unit provision should not disallow use of recirculating 

cooling reservoirs. The commenter appears to misunderstand the new unit provisions. The new 

unit provisions do not disallow use of a CCRS. 

Other Comments

Some commenters stated that smaller units and smaller communities will be most impacted by 

the cost of compliance. Other commenters stated that waste-to-energy facilities should be given 

greater flexibility regarding compliance. As discussed previously, the final rule imposes 

reasonable costs consistent with 316(b) requirements and includes significant flexibility that 

should enable existing facilities to identify cost-effective options. Further, the rule streamlines 

permit applications, compliance, monitoring, and other reduced requirements in certain 

situations. Section 316(b) does not provide for specific requirements for waste-to-energy 

facilities. EPA conducted a site visit to a waste-to-energy facility, and has not identified a basis 

for different standards. EPA also notes the commenter did not provide any data or examples of 

why waste-to-energy facilities should be given greater flexibility regarding compliance. 

Some commenters suggested applying the rule to new facilities only and grandfathering existing 

facilities until 2040. EPA disagrees with the comment. Not addressing existing facilities until 

2040 would not implement CWA section 316(b) or ensure that each CWIS reflects BTA. See 

preamble XI Implementation for more information on how the final rule schedule for 

implementation accounts for studies, IM, E determinations, and compliance. 

Some commenters indicated that it is not clear what it means for compliance costs to be wholly 

out of proportion. The entrainment provisions of this rule include a provision that allow the 

Director to determine that no additional entrainment controls are required at a particular facility 

if the Director finds that all the entrainment control technologies considered for the facility have 

social costs not justified by the social benefits of the controls. 

One commenter suggested some regulatory revisions to achieve consistency. Generally, in 

response to some comments and to ensure consistency and clarity in the rule, EPA has made 

certain edits to the final rule language. See the final rule and preamble. There is § 122.21r(ii)(A) 

and thus it is not clear which provision is being referenced. It should also be noted that some 

permit application requirements (e.g., § 122.21(r)(1)(ii)(B)) are in addition to basic permit 

application requirements for a specific category of facilities, and these should be read together. 

With regard to requiring AIF information as part of the permit application, § 122.21(r)(3) 

requires flow information at (iii) A narrative description of the operation of each of your cooling 

water intake structures, including design intake flows, daily hours of operation, number of days 

of the year in operation and seasonal changes, if applicable; and (iv) A flow distribution and 

water balance diagram that includes all sources of water to the facility, recirculating flows, and 

discharges. Because this information must be provided for each intake, there is generally no need 

to identify the facility-wide AIF as additional information. The Director can require additional 

information, including monitoring of the AIF, when needed. Further, those compliance 

alternatives that are based on actual flow already require flow monitoring; such as § 

125.94(c)(1), (3), (4), and (6). Finally, the final rule includes Entrainment Characterization Study 

provisions in the permit application portion of the rule. These provisions focus on development 

and submission of entrainment information and are appropriate in this part of the rule. 

Essay 14 77 
Essay 15: EPA’s Approach to Establishing Best Technology Available

316(b) Standards for New Units and Existing Units

Introduction

As described in the preamble to the final rule, in evaluating standards to minimize adverse 

effects associated with cooling water intake structures at existing facilities, the EPA reviewed the 

data from its previous section 316(b) rulemaking efforts as well as collecting and analyzing new 

data to evaluate the best technology available for existing facilities. In response to its proposed 

standards for existing facilities, EPA received a large number of comments on its proposed 

approach for determining what standards would reflect the best technology available for 

minimizing adverse environmental effects. These comments addresses area that included what 

regulatory framework that EPA should follow to determine these standards and the role of costs 

and benefits in evaluating “best technology available” as well as information about what specific 

technologies for reducing adverse effects should be adopted for the final rule. 

As discussed in section VI of the preamble, on the basis of the high levels (about 96 percent on 

average) of flow reduction obtained by properly operated cooling towers and the availability, 

feasibility and affordability of closed-cycle cooling at new units, EPA has identified wet cooling 

systems as the BTA technology for both impingement mortality and entrainment for new units at 

existing facilities. The EPA did not compare costs to benefits for new units (as defined in the 

final rule) because EPA does not know where a new unit will be built, what cooling water 

withdraws would occur at the new unit, what levels of impingement or entrainment would occur 

at the new unit, or when the new unit would be constructed. For more info on new units, also see 

Essay 20. 

The final rule establishes BTA standards for reducing impingement mortality and entrainment 

requirements for existing power generating facilities and existing manufacturing and industrial 

facilities that withdraw more than 2 million gallons per day (mgd) of water from a waters of the 

U.S. and use at least twenty-five (25) percent of the water they withdraw exclusively for cooling 

purposes. EPA’s determination of BTA standards followed a rigorous analysis of technology 

performance, the feasibility and applicability of different technologies in multiple settings and a 

reasoned assessment of the costs and benefits of the different approaches. Moreover, as 

described in section VA.A of the preamble the EPA considered a number of factors in its final 

determination of what should be the BTA standards, including many of same factors EPA looks 

at in establishing its BPT, BCT and BAT effluent limitations guidelines. 

For additional information, refer to the preamble to today’s final rule. 

Overall Approach to BTA for Existing Units

As noted above, EPA received a large number of comments on how the rule should be 

structured. As described in the preamble, EPA has promulgated a final rule that establishes 

requirements under section 316(b) of the Clean Water Act for existing power generating 

facilities and existing manufacturing and industrial facilities. For impingement, the final rule 

Essay 15 78 
establishes BTA standards for minimizing impingement mortality that include seven compliance 

alternatives, providing ample flexibility for all in-scope facilities. The alternatives include 

several options for “pre-approved” technologies and “streamlined” options, all of which are 

based on technologies for which EPA’s record demonstrates achieve reductions in impingement 

mortality that are comparable to the IM BTA – modified traveling screens with fish returns. The 

final rule also establishes the national BTA standard for entrainment. In the case of existing 

units, the rule does not prescribe a single nationally applicable entrainment reduction technology 

but instead establishes a framework that requires the Director to establish the BTA entrainment 

requirement for a facility based on site-specific data contained in the permit application. The 

entrainment requirements must reflect the Director’s determination of the maximum reduction in 

entrainment warranted after consideration of all factors relevant to the BTA determination at the 

site and must include consideration of the specific factors spelled out in the final rule. The permit 

application requirements in the final rule will ensure that the Director has adequate information 

for determining the BTA for entrainment. Refer to the preamble for details on each of these 

items. 

One large umbrella environmental organization, Riverkeeper, stated that EPA’s approach to 

establishment of BTA (i.e., rejecting a single uniform national standard for entrainment in favor 

of a national standard for data gathering and the process for a site-specific determination for 

entrainment) is illegal and that EPA must develop a nationally applicable standard that reflects 

BTA. As discussed in section V1.A of the preamble and in more detail below, the CWA is silent 

about what factors EPA should consider in its determinations under section 316(b) and in the 

face of this silence, EPA may consider a number of relevant factors. As EPA’s analyses and 

record show, facilities exhibit significant variability in their configuration and operations, 

arguing that uniform entrainment requirements are generally infeasible at the national scale. As 

such, the final rule appropriately establishes a national BTA standard for entrainment that is a 

process for a site-specific determination of entrainment requirements at existing CWIS. This 

provision further reflects EPA’s assessment that there is no technology that is BTA for 

entrainment at all facilities, based on a set of factors that are best accounted for on a site-specific 

basis. EPA also disagrees with the commenter’s interpretation of section 316(b) as a technologybased standard; see discussion of litigation history including the U.S. Supreme Court decision in 

the preamble at section II and the Essay 10. 

Approach to BTA for Entrainment at Existing Units/Facilities

Closed‐Cycle Recirculating Systems

Many commenters provided variable positions as to how to consider closed-cycle cooling such 

as wet cooling towers (or an equivalent level of performance based on the significant reduction 

in flow by a properly operated cooling tower) as the BTA standards basis for entrainment. 

Riverkeeper and other environmental groups argued that EPA should find closed-cycle cooling 

and cooling towers as the basis for section 316(b) BTA standards and that EPA incorrectly 

rejected this technology as the basis for entrainment standards. These commenters favored 

Option 3 (an option requiring closed-cycle at all facilities with a DIF greater than 2 mgd) as 

presented in the proposed rule. Riverkeeper noted that the flow reductions of closed-cycle 

cooling pose the most certain way to reduce entrainment. In support of this position, these 

commenters state that there are significant losses of aquatic life due to the operation of onceEssay 15 79 
through cooling water intake structures, that closed-cycle cooling is both available and 

affordable, and that EPA has established the final rule under the mistaken principle that best 

technology available implies that the technology must be universally available to all facilities. 

They suggest that the lack of a national entrainment standard will largely result in the status quo 

at facilities, resulting in no installation of technologies and therefore very little improvement. 

Riverkeeper further argued that the Second Circuit (in Riverkeeper I) determined that many of 

the factors cited by EPA in rejecting closed-cycle cooling were not valid. Some commenters 

provided detailed studies and analyses supporting these positions; EPA appreciates these 

submittals and the supporting studies and data, and has considered them in preparing the final 

rule. Some commenters also claimed that projected impacts to energy reliability as a result of the 

impacts of closed-cycle cooling are overstated; one commenter referred to a study that was not 

provided, so EPA was unable to verify the specific information. 

Industry commenters supported the proposed rule’s position that closed-cycle cooling is not 

available at the national level, which in the commenters view is a position supported by the 

Entergy decision. These commenters also agreed with the approach of the proposal to determine 

entrainment on a site-specific basis. 

Some industry and some environmental group commenters provided detailed studies (including 

analyses of reliability, costs, benefits, feasibility, the universe of affected facilities, and other 

non-water quality environmental impacts) supporting these positions; EPA appreciates these 

submittals and considered them in preparing the final rule. 

Some commenters (including states) supported the proposed rule regulatory framework of 

flexible approach to IM requirement and a framework for site-specific entrainment requirements. 

They noted that a site-specific approach is preferable for entrainment, allowing consideration of 

multiple factors most relevant to the particular location. Others suggested that EPA adopt a 

“rebuttable presumption” for closed-cycle cooling as BTA. Another state commenter argued that 

closed-cycle cooling was the clear choice as the best technology available for similar reasons 

stated by environmental groups. A state commenter agreed with EPA’s proposal that closedcycle cooling was not feasible at all facilities, but that EPA should require BTA entrainment 

standards that reflect equivalent (or nearly so) performance at those sites where closed-cycle 

cooling is infeasible. These state commenters did not provide data or suggest what technology 

these alternatives to closed-cycle might be based on. 

Another commenter stated that the approach taken in the proposed rule was contrary to EPA’s 

historic approach as well as the Agency’s position in Riverkeeper I. Some commenters state that 

EPA failed to describe how a BPJ-based approach is comparable to closed-cycle cooling, which 

in their view is required by Riverkeeper II. 

As explained in the preamble, closed-cycle cooling based on wet cooling towers is a highly 

effective technology for reducing both impingement and entrainment. However, with respect to 

entrainment, the EPA has concluded that it should not adopt a BTA entrainment standard 

prescribing a uniform national technology with a requirement for a (CCRS) closed-cycle 

recirculating system based on wet cooling towers. EPA concluded that closed-cycle cooling is 

not an available entrainment reduction technology on a national scale and therefore should not 

form the basis for the “best technology available” entrainment standard. The record shows that 

Essay 15 80 
closed-cycle cooling is not technically available in a number of circumstances either because (1) 

land availability and geographical constraints could be a factor on a local basis (such as limited 

space available to install cooling towers, noise mitigation, and setback distances for plume 

abatement); (2) increased air emissions (such as due to the need for increased fuel burned to 

operate the cooling towers); and (3) remaining useful plant life (for example a plant scheduled to 

be shutdown in 3 years will result in very little entrainment reductions as compared to a facility 

that will continue to operate for a significantly longer period). In addition, EPA analyzed other 

factors in addition to availability in reaching its conclusion not to base the BTA entrainment 

standard on closed-cycle cooling. 

To be clear, EPA did not conclude that closed-cycle cooling is not available at every facility. Nor 

has EPA rejected CCRS on grounds that the technology is not economically achievability. While 

EPA did consider costs, costs were not a dispositive factor in the decision to reject CCRS based 

on cooling towers. Rather, EPA considered its applicability to the industry as a whole. That is, 

the record demonstrates that while EPA cannot identify with precision the extent of these 

limitations on installing closed-cycle cooling systems nationwide, the record indicates that the 

circumstances are neither isolated nor insignificant. EPA tried to identify characteristics for 

which it has information that would allow it to subcategorize those facilities where closed-cycle 

is not available (e.g., land size threshold), but was unable to do so and concluded that such 

determinations can only be made on a site-specific basis consideration; see TDD for further 

discussion. Furthermore, contrary to the statement made by some commenters, EPA reasonably 

concludes that the availability of a technology to the industry is an appropriate factor for 

evaluating BTA technology bases for national standards. EPA has historically evaluated the 

availability of a technology to the industry in making technology base determinations for other 

national technology based performance standards. For more information on the reasons EPA 

rejected closed-cycle cooling as the basis for national BTA entrainment requirements, see the 

preamble. 

Some commenters stated that there are other technologies, where cooling towers are infeasible, 

that would allow such facilities to comply with performance standards based on cooling towers 

as BTA. One commenter argued that wedgewire screens can offer comparable performance to 

closed-cycle cooling. 

EPA disagrees with the commenters supporting performance equivalent to CCRS is BTA. EPA 

has concluded that performance equivalent to CCRS is not BTA because there are no available, 

demonstrated, and feasible technologies on which to base such requirements. Most commenters 

did not suggest what technologies demonstrated a performance comparable to CCRS. While 

several commenters submitted studies, none of the commenters provided performance data that 

demonstrated performance comparable to CCRS. More specifically, with respect to traveling 

screens, modified traveling screens offer no reduction in entrainment unless the screens consist 

of fine mesh. With respect to fine mesh screens (both passive and traveling screens) the record 

shows that CCRS reduces the entrainment mortality of eggs and larvae 8-fold more than fine 

mesh screens (based on the mean value of performance data for both eggs and larvae); see TDD 

Chapter 6 for more details. While some sites obtained reductions in entrainment with one or 

more technologies including fine mesh screens, EPA found the studies did not distinguish 

between intake location (such as offshore submerged intakes) and the fine mesh screens 

themselves. Most studies submitted by industry showed a bias towards older/larger larvae, which 

Essay 15 81 
                                                            

 

are generally more developed life stages of fish and shellfish. These older life stages are starting 

to exhibit survival traits and avoidance responses. These studies are poor indicators of 

performance for eggs and early life stages, which have no avoidance response (eggs can’t swim) 

and no protective features (no skeletal structure or incomplete formed structure, and no scales). 

The submitted studies also did not fully characterize survival of entrainable organisms; in other 

words, these studies often characterize entrainable exclusion, and did not measure entrainable 

survival. These studies are therefore rejected as supporting fine mesh performance is comparable 

to CCRS. 

In addition to EPA concluding fine mesh performance is not comparable to CCRS, EPA’s 

analysis shows fine mesh is not widely available. Overall, EPA’s technical analysis shows 68 

percent of facilities would need to expand the size of their intake10 by more than five times to 

accommodate a retrofit to fine mesh, and the vast majority of these sites do not have sufficient 

water front space or water depth to accommodate such an expansion. In addition to limited 

source water depth and well depth, EPA notes that even if fine mesh performance was 

comparable to CCRS, fine mesh is not available at an estimated 17 percent of facilities based on 

existing intakes that need to be enlarged to accommodate 2.0-mm fine mesh. Similarly, enlarging 

the existing intakes to accommodate a reduced open surface area when retrofitting to 0.5-mm 

mesh is unavailable for at least 55 percent of facilities. These analyses and supporting data lead 

EPA to conclude that fine mesh screens would not be an available technology at a significant 

number of sites. EPA did not receive any new data to the contrary. In addition, EPA recognizes 

that high sediment waterbodies pose a challenge for fine mesh screens, and high sediment water 

can cause “blinding” of the intake. For all of these reasons, fine mesh screens do not offer 

survival of entrainable organisms to the extent CCRS does, and EPA rejects all comments stating 

that fine mesh performs comparable to CCRS. See preamble VI.C for further discussion of fine 

mesh screens. 

EPA agrees that other technologies (such as variable speed pumps or variable frequency drives, 

seasonal shutdowns) may be effective at some sites, and facilities are encouraged to implement 

such technologies to reduce entrainment, EPA’s analysis showed that these technologies also do 

not achieve the same level of reduction in entrainment as closed-cycle cooling. Variable speed 

drives can achieve a maximum of 10 to 15 percent reduction in flow; the average flow reduction 

is about 8 percent for those sites where the technology is available. Therefore CCRS is 

approximately an order of magnitude better in performance than VFDs. Seasonal shutdowns are 

not available at baseload power generating facilities, nor are they available at most 

manufacturing sites, because these facilities operate year round. Shutdown during peak 

entrainment seasons is not viable for these facilities. See preamble VI.C for more discussion. 

Upon full consideration of all comments and data, EPA has concluded that performance 

equivalent to CCRS is not BTA (because there are no available, demonstrated, and feasible 

technologies on which to base such requirements). 

To reiterate, EPA concluded that closed-cycle cooling is the most effective technology and there 

is a gap in performance (when viewed at the national scale) between closed-cycle cooling and all 

10 Fine mesh screens reduce the open screen area available for water to flow through the screen. To maintain 

approximately the same volumetric flow and the same intake velocity so as not to cause adverse plant operations, the 

intake therefore must be expanded with additional screen bays to provide the requisite open screen area. 

Essay 15 82 
other technologies with regards to entrainment As discussed above, closed-cycle cooling 

provides an average of 96 percent reduction in entrainment. According to EPA’s record, one of 

the next most effective technology with regards to entrainment is fine mesh screens. Also as 

discussed above, the record shows that fine mesh provides less than 12 percent survival of 

entrainable organisms at 0.5-mm mesh size (mean value for eggs and larvae combined), and no 

protection of eggs at a 2.0-mm mesh size. In addition to this performance gap, there is a lack of 

nationally available technologies. For all of these reasons, EPA did not identify an available 

candidate technology on which to base entrainment performance standards. As discussed above, 

since technologies other than closed-cycle cooling may offer some level of entrainment reduction 

at some sites, EPA’s final rule includes requirements at § 122.21(r)(10) to develop a 

Comprehensive Technical Feasibility and Cost Evaluation Study. 

EPA also disagrees that under section 316(b), the EPA may only consider one factor - the 

performance of different entrainment reduction technologies - in determining BTA requirements 

under section 316(b). Riverkeeper I and II and the U.S. Supreme Court’s decision in Entergy 

establish that, while EPA may consider the factors specified in sections 304 and 306 as relevant 

factors in its decision-making, it is not limited to those factors. Section 316(b) is a separate and 

distinct statutory provision from section 301, 304 and 306. (See, for example, page 1506 of 129 

S. Ct., which concluded that EPA is not bound to apply only those factors. The court noted that 

the BTA standards of section 316(b) must “minimize” adverse environmental impacts and 

contrasted that with the Congressional goal to “eliminate” the discharge of pollutants. Also, the 

Supreme Court noted that 316(b) contains broader language with additional discretion, 

describing the statute’s silence on certain issues as an indication to “convey nothing more than a 

refusal to tie the agency’s hands.”) As a consequence, while EPA may consider factors like those 

considered in developing its effluent limitations guidelines, EPA has discretion to consider other 

factors in its decision-making under 316(b). See preamble section II and Essay 10 for more 

details. 

EPA disagrees that the final rule will perpetuate the “status quo” of inaction on 316(b) 

requirements. Section 125.90 makes it clear that all CWIS must meet the requirements of section 

316(b), including those CWIS at facilities not in scope of the final rule. Today’s final rule 

establishes a schedule for submitting permit applications and studies, provides the Director and 

the public with new and significant information, and ultimately establishes a rigorous process for 

determining BTA for each facility. Notably, while site-specific permit requirements are not new, 

what is different about EPA’s approach from the current requirement for permits to include 

316(b) conditions is that for the first time, EPA is establishing a detailed specific framework for 

determining BTA entrainment control requirements. Thus, the rule identifies what information 

must be submitted, prescribes procedures that the Director must follow in decision-making and 

factors that must be considered in determining entrainment requirements. See preamble for 

further discussion. 

EPA disagrees with the comment that facilities with closed-cycle should have no further study or 

reporting obligations. EPA’s record shows that there are existing facilities with closed-cycle 

cooling that do not optimize their operations to minimize water withdrawals. In some cases, 

facilities with cooling towers have been found to operate their cooling towers as once through 

cooling. Other cooling towers are operated at far lower than optimized cycles of concentration 

and with makeup water withdraws that are not minimized. Today’s final rule definition of CCRS 

Essay 15 83 
requires the facility to demonstrate to the Director that makeup water withdrawals have been 

minimized. Furthermore, periodic evaluation of the source waterbody is necessary to ensure no 

significant changes have occurred in the operation of the facility or in the source waterbody. For 

example, a species of local importance may warrant additional study, monitoring, or technology 

controls. For these reasons, EPA disagrees that there are any facilities that should have no study 

requirements as part of the permit application or reporting obligations under the permit. 

EPA also disagrees that the Riverkeeper I decision establishes the factors EPA consider in 

determining BTA. EPA has considered non-water quality environmental impacts to the extent 

such information was available. EPA further notes that more information on these impacts is 

available now than was available in the development of the Phase I and II rules. However, CCRS 

is rejected as BTA for the reasons stated above. See the preamble for more details on the factors 

EPA considered in determining BTA for entrainment. Examples of non-water quality and other 

impacts considered in this rule at § 122.21(r)(12) include changes to energy consumption, 

estimates of air pollutant emissions, changes in noise, impacts to safety, facility reliability, and 

consumption of water. Also see Essay 17A. 

Some commenters suggested low intake velocity was BTA. Riverkeeper noted that reducing the 

intake velocity will do little to reduce entrainment. 

EPA disagrees low intake velocity is BTA for entrainment. As discussed above, early life stages 

have no avoidance response, and therefore low intake velocity offers no protection to such 

organisms. With respect to theories regarding hydrodynamic influences of low intake velocity, 

EPA notes that egg and larvae exclusion do not equate to survival. Impact of eggs and especially 

early life-stages of larvae on a CWIS still cause damage and/or mortality of the organisms. Also 

see Essays 10 and 18. Therefore EPA agrees that reducing the intake velocity does not reduce 

entrainment and has assigned no reductions in entrainment to intake velocity-related compliance 

options. 

Approach to BTA for Entrainment at New Units Constructed at Existing Facilities

New units are required achieve performance commensurate with that which can be attained by 

the use of CCRS because the technology is available, demonstrated, and achievable; see 

preamble for further discussion. The final rule at § 125.94(e)(2) provides the flexibility for 

facilities to demonstrate, on a site-specific basis, a system of technologies approach that provides 

performance comparable to CCRS. Because new units are required to achieve performance 

commensurate with that which can be attained by the use of CCRS (at § 125.94(c)(12)), the 

above discussion of lesser performing technologies for entrainment at existing facilities is 

obviated. 

Other Technologies for BTA for Entrainment at Existing Facilities

One commenter argued that wedgewire screens can offer comparable performance to closedcycle cooling. The commenter did not provide comparability performance data. EPA disagrees 

that wedgewire screens perform comparably to closed-cycle cooling, especially with respect to 

entrainment. To date, EPA has not identified any performance studies for wedgewire screens 

alone that support the position that these screens achieve a performance equivalent to that of 

Essay 15 84 
closed-cycle cooling systems. First, the screens must consist of fine mesh to have any bearing on 

entrainable eggs or larvae; see the TDD. Second, fine mesh wedgewire screens merely exclude 

entrainable organisms from being sucked into the facility because eggs have no avoidance 

response and thus do not necessarily result in reduced destruction of the eggs and larvae. This is 

in contrast to closed-cycle cooling which significantly reduces withdraw of cooling water in the 

first place. EPA acknowledges that wedgewire screens may result in reductions of entrainable 

organisms at some facilities (based on local species and life-stages found in the vicinity of the 

CWIS), and may prove to be effective at some sites as part of a systems approach to reducing 

adverse environmental impacts (such as in combination with a far offshore and deep submerged 

intake). EPA’s record suggests that a far offshore location with a deep intake, with variable 

speed drives, in combination with fine mesh has the potential for entrainment performance 

approaching that of closed-cycle. However, such an approach is not available at inland 

waterbodies such as rivers and streams. 

While the record shows fine mesh wedgewire screen performance is not comparable to CCRS, 

and is not BTA for the reasons discussed above, EPA is not prejudging the site-specific 

determination of entrainment. While EPA can address the overall performance of each 

technology considered in this rule (see TDD), EPA does not have sufficient data to opine on the 

facility-specific details raised by the commenter as to what technology is the best choice at a 

given site. The final rule establishes a process through which the facility will submit data and the 

Director will make a site-specific determination of BTA for entrainment. EPA’s BTA standard 

for entrainment requires the determination of BTA entrainment reduction controls in a structured 

process with consideration of specified factors as indicated above. This process allows the 

Director to consider a given technology or system of technologies performance at a given site, 

particularly installation and operation of a numbers of technologies that in combination may 

result in achieving reductions in entrainment necessary to achieve BTA at that site. For the same 

reasons, EPA is unable to pre-judge the timing of benefits when establishing a schedule for 

entrainment requirements at each site. 

Some commenters requested that EPA include cooling ponds in the definition of a closed-cycle 

system and that makeup water should be excluded from 316(b) requirements; refer to Essay 14 

for responses to this comment. Some commenters stated that the bulk of the burden of proof of 

having an adverse environmental impact falls to the Director instead of the facility, when the 

inverse would be more appropriate. Other commenters (including a state commenter) urged EPA 

to not promulgate a rule based on a site-specific determination of entrainment, as it reinforces 

industry’s positions of status quo, and would not further the goal of enhanced protection. 

EPA disagrees with each of these comments. As discussed above, the final rule is a significant 

improvement over the status quo. The studies required for certain facilities’ permit applications, 

including but not limited to peer reviewed information related to entrainment characterization, 

must be collected by the facility. The rule lays out a structured process by which entrainment 

will be addressed by each facility. Together, these requirements minimize adverse environmental 

impact through significant reductions in entrainment. Facilities will collect new data and 

Directors and the public will have access to this information. EPA disagrees with the adverse 

comments concerning cooling ponds and waters of the U.S. The definition of closed-cycle 

cooling does not preclude the use of cooling ponds, nor does this rule alter or define waters of 

the U.S which is outside the scope of this proceeding. Hundreds of studies in EPA’s record 

Essay 15 85 
document impingement and entrainment occurring at all CWIS, including all waterbodies, types 

of intakes, and locations. Commenters did not provide any data to the contrary; even industry 

commenters providing data that their facility poses a de minimis AEI show impingement and 

entrainment. Therefore, there is no need for further proof that a CWIS subject to this rule has the 

potential for having an adverse environmental impact. The site-specific level of adverse 

environmental impact will vary, further supporting EPA’s conclusion that BTA for entrainment 

includes a framework and the factors for determining BTA requirements. 

Some commenters argued that EPA should clarify that there is no BTA for entrainment and 

allow the Director to establish entrainment controls. EPA disagrees with the notion that there is 

no BTA. EPA has determined that there is no available technology on which EPA can establish 

performance standards for entrainment. However, the final rule establishes as the BTA standard 

the requirement to determine for each facility in a structured process the site-specific entrainment 

reductions measures that comprise BTA for that site. 

Some state commenters advocated for national entrainment requirements, noting that a sitespecific approach would be too resource intensive; alternatively, they called on EPA to provide 

guidance, funding or staffing. EPA disagrees. As noted in the preamble and above, EPA 

concluded that national entrainment numerical performance standards were not appropriate. With 

respect to intensive resources, EPA also disagrees. All facilities must submit source water 

baseline characterization, cooling water system data, existing entrainment characterization 

studies, and other information as part of the permit application at § 122.21(r)(1) through (8). 

Facilities that withdraw greater than 125 mgd must submit detailed entrainment characterization 

studies, technical feasibility and cost evaluations, and other relevant data. The complete 

Entrainment Characterization Study must be peer reviewed. EPA has considered all costs 

associated with studies and peer review, and the final rule establishes these requirements on the 

facility. This permit application process thus places the relevant information in front of the state 

Director. The final rule at § 125.98(g) provides Directors the discretion to waive certain 

requirements for an ongoing permit proceeding. The final rule also provides Directors the 

discretion to waive certain permit application requirements; see § 125.95(a)(3). Further, EPA has 

defined a process by which site-specific determinations are made based upon these studies and 

data. See § 125.98 for details regarding the factors to be considered and the process for 

determining BTA for entrainment. Additional costs have been included for the Director’s review 

of the submitted information and final determination of BTA. EPA finds these costs are not 

burdensome. For further information see the discussion of UMRA in section XI.D of the 

preamble. EPA will evaluate the need for further guidance after publication of the final rule as 

the final rule will be implemented through the Directors’ existing NPDES state programs. 

Some commenters stated that because the proposed rule fails to address entrainment, the rule 

leaves a majority of the impacts unregulated. Other commenters added that the apparent lack of 

adequate entrainment control technologies should encourage additional research. Some 

commenters stated that the rule should, at a minimum, achieve the lower end of the performance 

range from the Phase II rule. 

EPA disagrees with all of these comments; the final rule does address entrainment by 

establishing a process for collecting information and providing it to the Director to make a sitespecific determination of BTA. “Site-specific” does not equate to “unaddressed.” EPA also 

Essay 15 86 
disagrees that it can establish requirements on the premise of technologies that have yet to be 

developed. EPA can realistically only base performance standards upon technologies that are 

available and demonstrated at the present time. As noted in the preamble and in the proposed 

rule, EPA has changed its approach to addressing entrainment since the Phase II rule primarily 

based on new data, as well as a more complete understanding of the difference between 

entrainment exclusion and entrainment mortality. Further, some of the Phase II rule entrainment 

requirements are no longer authorized (restoration). The performance range is now known to 

represent exclusion, and does not represent reductions in entrainment mortality. Accordingly, the 

Phase II performance range for entrainment no longer reflects BTA. As discussed above, there 

are no intermediate performing technologies for entrainment. For all of these reasons, a 

percentage-based approach to reducing entrainment is no longer relevant. EPA agrees that CCRS 

must be considered in the rulemaking, but disagrees with the interpretation that Riverkeeper II 

mandates that EPA mandate closed-cycle cooling in future rulemaking (i.e., this rule). The 

Supreme Court decision in Entergy reversing the Second Circuit in Riverkeeper II made it clear 

that EPA has wide discretion in the factors it considers in its section 316(b) decision. 

Approach to Impingement BTA at Existing Units/Facilities

As indicated above, industry commenters argued that facilities with existing closed-cycle cooling 

systems should be considered compliant for both impingement mortality and entrainment, and 

that such facilities should not have any additional impingement requirements. Some industry 

commenters noted that EPA’s assumption that all facilities employing closed-cycle cooling (as a 

retrofit) would meet the design intake velocity threshold of 0.5 fps, and thus would meet the 

proposed rule requirements for IM, was erroneous. Some industry and some environmental 

group commenters provided detailed studies (including analyses of reliability, costs, benefits, 

feasibility, the universe of affected facilities, and other non-water quality environmental impacts) 

supporting these positions; EPA appreciates these submittals and considered them in preparing 

the final rule. 

Another state commenter added that modified traveling screens should be considered preapproved compliance technology for the impingement BTA standards. The commenter further 

suggested that for intakes supporting a closed-cycle cooling system, such intakes should have no 

further study requirements. 

Based on the record for the final rule, EPA agrees with commenters that facilities with an 

existing closed-cycle system that is properly operated and maintained will meet or exceed the 

impingement mortality performance standard regardless of their intake velocity. This is because 

CCRS, on average, will reduce flows by 96 percent. This reduction in flow results corresponds to 

a 96 percent reduction in the rate of impingement. Accordingly, EPA agrees with the concept 

that facilities with closed-cycle cooling should have reduced study requirements. This is 

reflected in the final rule definition at § 125.94(c), and the permit application requirements at § 

122.21(r). See preamble for further discussion of reduced study requirements. 

With respect to IM, EPA disagrees with the comment that facilities with closed-cycle should 

have no further study or reporting obligations for the reasons stated above for entrainment. EPA 

also disagrees with the comments suggesting no studies, monitoring, or evaluation of further 

technologies need be conducted. First, a properly operated CCRS could withdraw more than 100 

Essay 15 87 
mgd each day, and could still be imposing an AEI. Second, installing the technology does not 

mean it is being properly operated; EPA found several instances where a cooling tower has been 

installed but not operated to minimize the volume of withdrawn. See 77 FR 34319. Therefore, in 

the final rule facilities with CCRS must demonstrate the makeup water has been minimized; see 

§ 125.94(c). Third, even where the facility already has CCRS, the characterization studies and 

source water baseline data may indicate additional measures are necessary for shellfish, fragile 

species, or other aquatic organisms. The Director may make such a determination under § 

125.94(c)(8) and (9). Finally, the record shows that for at least 10 percent of all facilities, the 

cooling water intake system may be comprised of more than one technology, and that 24 percent 

of manufacturers and 33 percent of electric generators have more than one CWIS; see TDD 

section 4.1.4. The rule provides the flexibility for the facility to demonstrate compliance for each 

intake, or at the facility level, but in either case further evaluation is necessary to determine 

whether the IM standard has been met. 

The final rule establishes a standard for impingement mortality (with seven compliance 

alternatives) that must be achieved by all in-scope facilities. EPA has found that each alternative 

meets or exceeds the level of performance achieved by the selected BTA technology. See the 

preamble for discussion of each of these alternatives and the basis for each. 

Riverkeeper opposes a site-specific approach to determining BTA for impingement. Riverkeeper 

stated that closed-cycle cooling is the best approach to reducing impingement and barring that, 

reducing the intake velocity is next most effective; they also argue that facilities should employ 

both technologies. Riverkeeper stated that EPA’s own data show that a large number of facilities 

already meet the velocity standard and that the percent reduction in impingement is higher than 

that of the performance standard for traveling screens. Riverkeeper also stated that the rule 

should not allow degraded waters to influence the process for determining BTA. 

EPA has established a national impingement mortality standard in today’s final rule and, as such, 

agrees that a site-specific requirement for impingement mortality is not BTA; see the preamble 

for more information. While the BTA impingement mortality standard for the final rule is based 

on the performance of modified traveling screens, the rule does not require the installation and 

operation of this technology. Instead, EPA provided seven alternatives means of achieving the 

performance associated with well-operated modified traveling screens. EPA agrees that both 

closed-cycle cooling and reduced intake velocity are very effective in reducing impingement, 

and therefore impingement mortality. Therefore the final rule includes both of these technologies 

as compliance alternatives. EPA did not base the impingement mortality performance standard 

on these technologies for existing units as suggested by the commenter, because the record 

demonstrates that these technologies are not available on a national scale. See the discussion 

above and in the preamble on the availability of closed-cycle cooling. See Essay 17 and the TDD 

for a similar discussion on the national availability of reduced intake velocity technologies, and 

the preamble for further discussion of why low intake velocity is not BTA. 

Riverkeeper supports their assertion that intake velocity should be the technology basis for the 

BTA impingement standard for by citing data from the Phase I rule on the extent to which new 

facilities have low intake velocities. EPA notes that the data cited referred to facilities 

constructed in the prior 15-year period. EPA agrees that newer facilities tend to have lower 

intake velocities, but today’s final rule addresses all existing facilities, including those that are 

Essay 15 88 
much older, and the percentages of existing compliant facilities cited is much lower. In fact, 

EPA’s cost analysis (which used industry survey data for the entire universe of existing power 

generating facilities) estimated that approximately one-third of the in-scope universe would 

comply using the design intake velocity option; some existing intakes already have a compliant 

velocity and others would install a technology to reduce their intake velocity to 0.5 fps. EPA 

agrees that reducing the intake velocity is a highly effective approach, but as noted above, it is 

not an available technology for many facilities and therefore is not appropriate to consider as the 

basis for a national BTA for impingement. EPA has identified a most effective technology for 

IM that is available at most facilities, established a performance based on that technology, and 

then identified a number of ways in which this level of performance can be achieved. Intake 

velocity and closed-cycle cooling both achieve the required level of performance, therefore such 

technologies (where feasible at a facility) would allow existing units to comply with the final 

rule IM requirements. EPA notes that the final rule is not based on the condition of the receiving 

waters (or intake waters), as all waters are treated equally in terms of establishing appropriate 

requirements. 

EPA disagrees with commenters that facilities that employ closed-cycle system that are properly 

operated and maintained should additionally have to meet an impingement requirement based on 

reduced intake velocity. As explained above, EPA concluded reduced intake velocity is not 

available nationally. Comments and data received on the proposed rule show that not all facilities 

with CCRS would meet the 0.5 fps intake velocity. Furthermore, EPA’s record demonstrates that 

facilities that utilize such closed-cycle cooling systems have correspondingly reduced 

impingement (and entrainment) mortality by approximately 96 percent. Therefore, any additional 

requirements on facilities with properly operated CCRS would further reduce IM by at most 1 to 

4 percent. EPA has determined the BTA for IM as discussed above; properly operated CCRS 

achieves the BTA IM standard. Therefore EPA disagrees that all existing facilities with CCRS 

should be additionally required to demonstrate reduced intake velocity. 

Industry commenters stated that the proposed rule’s impingement requirements are too 

inflexible. Commenters further suggested that site-specific approach for impingement mortality 

(including consideration of costs and benefits) would be preferable, appropriate given EPA’s 

history of site-specific evaluation of BTA, and less costly to facilities and consumers. 

As discussed in Essay 24 and as noted in the preamble, EPA disagrees that the IM requirements 

are inflexible. EPA did not propose and is not today establishing requirements to install modified 

traveling screens. As noted in the preamble, EPA has promulgated a final rule with seven IM 

compliance alternatives, including compliance alternatives for both pre-approved and 

streamlined technologies as suggested by commenters. The last alternative provides an 

opportunity to demonstrate new and innovative technologies and approaches that achieve the IM 

performance standard. EPA concludes the rule provides ample flexibility. EPA also disagrees 

site-specific IM is less costly that EPA’s flexible final rule; in some cases the burden of data 

collection studies, biological assessments, pilot studies, site-specific engineering assessments, 

and other factors makes the site-specific IM determination process alone more costly than a 

facility implementing one of the seven compliance alternatives. As discussed in the preamble, 

EPA has found the suite of technologies for IM to be affordable, available, feasible, 

demonstrated and effective. Therefore, EPA disagrees that a site-specific approach is appropriate 

for impingement mortality. See below for a discussion of the role of costs and benefits. 

Essay 15 89 
Role of Costs and Benefits in Determining BTA

Many commenters stated positions on how (and whether) EPA should consider costs and 

benefits in the final rule. These comments generally fit into several categories, as discussed 

below. 

Cost‐Benefit/Benefits Must Justify the Costs/Maximize Net Benefits for the Final Rule

Environmental commenters state that EPA should not rely on cost-benefit analyses and should 

prohibit Directors from considering cost-benefit analyses. They also stated that cost-benefit 

analysis is intended to be a screening tool to rule out absurd results and not to make significant 

regulatory decisions; as a result, EPA’s reliance on cost-benefit is illegal. Riverkeeper also stated 

that there was no cost-benefit analysis for Phase I or for offshore industries in Phase III and 

therefore none should be conducted in the existing facility rule. Riverkeeper argued that EPA has 

overestimated compliance costs and underestimated the benefits of the rule, resulting in a skewed 

cost-benefit ratio. They state that, with partial corrections to these analyses, Option 3 becomes 

the clear choice for the final rule, as the benefits exceed the costs. Riverkeeper argued that EPA 

stated that Proposal Option 1’s benefits were justified by the costs, but did not state a conclusion 

for the same test for Options 2, 3 and 4. Environmental commenters also noted that there is a 

significant burden on the Director, who will be required to make decisions with little to no 

guidance, adding that states lack the expertise and resources to conduct the same extensive 

analyses of costs and benefits as those conducted for the final rule. They argued that EPA has 

spent years developing its analyses (even exceeding the level of effort typically afforded to a 

BPT threshold) and cannot reasonably expect that states can reproduce this level of effort and 

will therefore likely fail to fully account for benefits to be gained by closed-cycle cooling. 

Environmental commenters also stated that, if cost-benefit analyses are allowed, EPA should set 

limits on how they will be implemented. They further stated that OMB altered language related 

to considering costs and benefits. Some environmental commenters stated that EPA should 

conduct a break-even analysis when costs exceed the benefits. 

Many industry commenters stated that the final rule should have benefits that are commensurate 

to or greater than the costs of the rule. Some commenters argued that EPA has not explained its 

rationale for taking action, asserting that the costs are not justified. Similarly, several 

commenters stated that EPA had failed to comply with Executive Order (EO) 13563, titled 

“Improving Regulation and Regulatory Review.” Some comments stated that EPA had not 

maximized the net benefits, as directed by the EO. Other commenters argued that EPA had not 

demonstrated that the rule’s costs were justified by its benefits, as directed by the EO. Many 

commenters also pointed out that the Entergy decision permits EPA to consider costs and 

benefits and that EPA should do so, in keeping with past practice for 316(b). These commenters 

noted that the cost-benefit ratio for the proposed rule was approximately 21 to 1 and that that 

ratio did not include any consideration of costs to address entrainment, which one commenter 

noted was inconsistent with EO 12291. Some commenters stated that Option 3 had the worst 

cost-benefit ratio among the options considered, suggesting that the application of closed-cycle 

cooling is not an appropriate national requirement and that a conversion to closed-cycle cooling 

would be applied only in limited circumstances. Some commenters stated that the disparity in the 

costs and benefits for the rule failed the Administrative Procedure Act’s test of “reasonableness.” 

Another commenter stated that EPA had pre-judged the outcome of the incomplete stated 

preference survey and used those results to conclude that the rule’s benefits justify the costs. 

Essay 15 90 
Some commenters provided a summary of EPA’s guidance document for conducting cost-benefit 

analyses or a detailed discussion on how to conduct a cost-benefit analysis. 

A state commenter noted that state policy was to conduct a cost-benefit analysis and discourage 

negative impacts to the state economy and employment. The commenter argued that “benefits 

justify the costs” would constitute backsliding, as well as place an undue burden on the Director 

to justify any action. Another state commenter added that EPA should eliminate any 

requirements to evaluate costs and benefits at the facility level, given that EPA was unable to 

develop a complete analysis for the final rule. 

Other commenters argued that EPA should define the threshold for “benefits justify the cost” as 

being comparable to one another or to have a net positive benefit. Another state commenter 

preferred to continue using the “wholly disproportionate” threshold, as it had already withstood 

several legal reviews Several commenters stated that the threshold of “benefits justify the costs” 

is superior to the current threshold of “wholly disproportionate” and Phase II’s “significantly 

greater.” Some commenters advocated instead using the threshold of “benefits exceed the costs.” 

One commenter stated that the Clean Water Act did not support the use of the “wholly 

disproportionate” test. Another commenter noted that in the Phase II rule, EPA determined that a 

cost-benefit ratio of 5 to 1 was considered “wholly disproportionate” and had no basis to change 

this threshold in the final rule. Other commenters noted that, in the Phase III rule, EPA 

concluded that the costs for regulating land-based facilities (small power plants and 

manufacturers) was not justified, yet the Phase III rule had a cost-benefit ratio that is very similar 

to that of the final rule. They added that EPA has not explained why the underlying logic of these 

decisions has changed. 

EPA agrees the appropriate standard is wholly disproportionate. EPA notes commenters have 

confused this with the EO 13563, as discussed below. In Riverkeeper II, the court decision states 

“because cost is not supposed to be a paramount consideration in determining BTA, see 

Riverkeeper I, 358 F.3d at 185, the “significantly greater than” standard poses substantial 

concerns.” The court also noted discomfort with the “significantly greater than” standard of 40 

CFR 125.94(a)(5)(i), given the historical applicability of a “wholly disproportionate to” standard 

and the use of the latter standard in the Phase I Rule. EO 13563 directs EPA and other Federal 

agencies to identify and use the best, most innovative and least burdensome tools for achieving 

regulatory ends. In its regulatory actions, agencies “must take into account benefits and cost, 

both quantitative and qualitative,” and to the extent permitted by law, only promulgate 

regulations that are based on “a reasoned determination that its benefits justify its costs 

(recognizing that some benefits and costs are difficult to quantify)” (see section 1(b)(1)). EPA 

has improved its analysis since Phase II, and has used the best available science regarding widely 

accepted tools and data to monetize the benefits of the various options in four major categories: 

recreational fishing, commercial fishing, nonuse benefits, and benefits to threatened and 

endangered species. EPA has concluded that the benefits estimated for the first two categories 

are generally complete, while the benefits estimated for the latter two categories are far from 

being complete for a number of reasons. For example, the nonuse benefits consider only one 

species and only for the northeast and middle Atlantic states. See preamble section VI.F for 

further discussion. The Phase II rule, like today’s final rule, had many benefits that were not 

quantified and were therefore not monetized. As a result, the Phase II cost-benefit ratio cited by 

commenters provides an incomplete comparison of the costs and benefits. With respect to Phase 

Essay 15 91 
III, EPA based the decision on its judgment that the monetized costs associated with the primary 

option under consideration are wholly disproportionate to the monetized environmental benefits 

to be derived from that option. EPA was unable to assign a monetary value that fully captured 

the value of avoiding the environmental impacts that EPA had identified because the necessary 

information was not available. EPA did attempt in the Phase III rule to monetize the loss of 

forage fish indirectly through its impact on reducing commercial and recreational harvests, and 

found these impacts to be generally small. However, this approach does not capture the value 

that society may place on these fish for their own sake. Therefore, EPA only considered nonuse 

benefits qualitatively. EPA has since collected additional data, conducted supplemental analysis 

and explored additional regulatory options. EPA explained the basis for its proposed rule and 

solicited comment. Therefore EPA disagrees that the rationale for any changes to the Phase II or 

Phase III rules has not been provided. 

Other commenters stated that EPA should present a full cost-benefit analysis in the final rule. 

Some commenters noted that EPA conducted a summary-level cost-benefit analysis in the 

proposed rule, yet still selected an option that had a worse cost-benefit ratio that other options. 

For the final rule, EPA estimated both the compliance costs and its projected benefits and has 

fully considered both analyses in its decision-making. EPA recognizes that commenters 

expressed a wide range of opinions on how to consider costs and benefits in the final rule, noting 

that there are many considerations, resources, and precedents to bear in mind. In fact, Justice 

Breyer’s opinion in Entergy recognizes the difficulty associated with monetizing benefits. After 

evaluating these comments, past practice of implementing 316(b), and case law, as explained in 

the preamble, EPA concludes it has permissibly and appropriately considered costs and benefits 

in this final 316(b) rule. EPA notes that cost-benefit analyses in other regulations are not 

relevant. EPA disagrees that previous Agency decisions from the Phase I or Phase III rule are 

binding for this final rule because EPA has collected new data, developed new options, solicited 

further public comment, has new case law, and is considering the more complete body of 

information and analysis now before it. As recognized in Entergy, under section 316(b), EPA 

may consider, but is not required to consider, costs and benefits even if benefits are nonmonetized. In this case, EPA exercised its discretion to consider monetized cost and benefits as 

one of many other factors it evaluated in selecting the final regulatory option. 

EPA also disagrees that it has not complied with EO 13563 or the APA. The Agency considered 

a number of regulatory options, including a consideration of the costs and benefits for each 

option, and solicited comment on all aspects of the rule. As described in the preamble and in 

other responses to comments, EPA has considered both the monetized and non-monetized costs 

and benefits in developing the final rule and has therefore fully complied with EO 13563. EPA 

disagrees that comparing only monetized costs to monetized benefits is an appropriate test that 

trumps all other Clean Water Act factors for evaluating regulatory options; this casts a shadow of 

doubt onto any “benefits that justify the costs,” “maximize net benefits,” or “benefits that are 

commensurate with the costs” comparisons that are strictly numeric. EPA notes that the 

monetized benefits in the final rule do not capture all of the benefits that are projected to result 

from today’s rule. For this reason alone, a comparison of only the monetized costs and benefits 

poses an incomplete evaluation of the full range of costs and benefits that would result from each 

option considered. 

Essay 15 92 
Additionally, many commenters cited only part of the text of the EO; the EO subsequently 

continues: “In applying these principles, each agency is directed to use the best available 

techniques to quantify anticipated present and future benefits and costs as accurately as possible. 

Where appropriate and permitted by law, each agency may consider (and discuss qualitatively) 

values that are difficult or impossible to quantify[.]” As described in the preamble, EPA has 

applied the principles spelled out in EO 12866 and EO 13563. The EPA assessed total costs and 

benefits of the regulatory option for the final rule and has reasonably determined that the benefits 

of the rule justify the costs. In this way, EPA considered both costs, benefits, and the relationship 

of the two in selecting today’s impingement and entrainment mortality requirements. While the 

rule costs exceed the monetized benefits as presented, EPA has concluded that the costs do not 

outweigh total benefits when both monetized and nonmonetized benefits are considered. EPA 

notes that the monetized benefits are only a subset of all benefits. In the absence of complete 

estimates of nonuse benefits, EPA estimated partial nonuse benefits for the final rule using the 

benefits transfer approach from proposal. This approach is still a partial estimate, because it 

concerns only one species in two coastal regions; see the preamble for additional discussion. 

EPA disagrees that it has miscalculated the total national monetized costs and benefits (including 

those for closed-cycle cooling), thus leading to faulty decision-making for selecting a regulatory 

option. EPA has updated its costs and benefit analyses since the proposed rule, solicited data and 

comments, and fully documented its costing (see the TDD and Essay 21). Therefore the EPA has 

the best and most recent data available. While costs (and benefits) were estimated and were a 

consideration while reviewing all regulatory options for the final rule, they are not the sole or 

primary factor in selecting BTA. Thus, even if EPA’s estimates of costs and/or benefits are 

incomplete (which they are to the extent that certain benefits cannot be quantified or monetized) 

or were found to be incorrect, EPA would not have selected a different regulatory approach. For 

example, as discussed above with respect to CCRS, EPA concluded cooling towers are not 

nationally available as a technology basis for controlling impingement and entrainment 

mortality. Therefore CCRS is not BTA irrespective of the national costs, benefits, and/or the 

relationship of the two. 

EPA agrees that a break-even analysis can be a useful tool for decision-making. See Essay 76 for 

a discussion of the break-even analysis EPA conducted for nonuse benefits in the final rule. 

EPA disagrees that a market-based approach suggested by some commenters is a viable solution 

for evaluating cost-benefit for this rule. EPA explored approaches involving trading in prior 

rulemakings; see, for examples 67 FR 17170 (April 9, 2002) for information. As noted in the 

Phase II response to comment document (see comment 316bEFR.034.027), trading of ecological 

resources is a far more complicated endeavor than pollutant trading and EPA declined to 

establish such a program. In EPA’s view, trading is a difficult concept in the context of 316(b). 

As appropriate, the Director could develop such a program on a state or watershed level. 

Consideration of Costs and Benefits on a Site‐Specific Basis in Establishing

Entrainment Controls ‐	General

EPA notes that it considered costs, benefits, and the relationship of the two in its consideration of 

options for the final rule. Because EPA has not identified a technology basis that is available, 

demonstrated, and achievable for a national standard, EPA determined there is no basis upon 

Essay 15 93 
which to conduct a cost benefit analysis on a site-specific basis. EPA notes this is in contrast to 

IM, where a technology has been identified as available, demonstrated, and achievable, therefore 

a cost-cost test is not necessary. The impingement mortality performance standard provides 7 

compliance alternatives, and additionally provides each facility the flexibility to comply at a 

facility level or at an intake level. The IM performance standard is economically achievable. And 

the costs of IM at the facility level have low variability. See TDD Chapter 12, the proposal at 76 

FR 22186, and the EA for more details. As such, the following discussion is specific to sitespecific entrainment standards only. 

As explained previously, the final rule requires that the Director must establish the BTA 

entrainment requirement for a facility on a site-specific basis. The requirements must reflect the 

Director’s determination of the maximum reduction in entrainment warranted after consideration 

of all factors relevant to the BTA determination at the site and must include consideration of the 

specific factors spelled out in the final rule. These considerations and factors are spelled out in 

the preamble and final rule. Some of the comments above relate to site-specific considerations 

for entrainment. 

Some noted that states are ill-equipped to conduct these types of site-specific entrainment 

analyses and that it would create an undue burden on the states. EPA disagrees. See above 

discussion regarding burden on states and the Director. Furthermore, EPA notes that permits 

containing 316(b) conditions have been issued for over 30 years under a BPJ-based approach that 

inherently considered costs and benefits in addition to various other factors. With respect to cost 

benefit, the final rule establishes a process by which relevant sampling, studies, and information 

is submitted to the Director. This process is expected to result in the appropriate information 

needed by the Director, and will likely reduce historic levels of burden on states. EPA notes that 

there is a long history of Director discretion and public participation in 316(b) permitting, and 

that the rule establishes a process (including a transparent, reliable peer review process) to 

provide consistent review, determinations, and permit issuance. EPA notes that while the process 

requires a cost-benefit analysis, in the event that the facility does not submit complete and 

relevant data to evaluate cost benefit, the Director may reject the incomplete data. Further, the 

Director may choose how to consider cost-benefit and what weight to afford it in determining 

entrainment standards. 

In response to state commenters, as noted above, the Director has discretion in how to consider 

cost-benefit analyses in determining appropriate permit requirements. As such, the final rule does 

not interfere with existing state policies on the treatment of costs and benefits. EPA disagrees 

that the final rule constitutes backsliding, as the Director may choose how to consider costbenefit and what weight to afford it in determining entrainment standards. EPA disagrees that 

additional cost-related variances are necessary, as the final rule already requires the Director to 

consider costs and benefits. 

One commenter considered it important that permit writers should obtain cost estimates that 

reflect the specific characteristics of each site and technology application and was concerned that 

the cost tool that EPA used in developing national costs would be used in lieu of cost estimates 

that reflect the specific characteristics of each site. They also recommend that potential 

electricity rates and reliability concerns be included in site-specific assessments. Another 

commenter was concerned that nonuse benefits could be considered on a site-specific level. A 

Essay 15 94 
commenter also stated that EPA did not conduct formal sensitivity analyses on most cost or 

benefit parameters. 

As noted above, the final rule establishes a framework for the Director to determine entrainment 

requirements on a site-specific basis, using information submitted by the facility on a variety of 

factors. EPA disagrees that the cost tool used for national level costing is a concern because the 

final rule at § 122.21(r)(10) requires an engineering study, an engineering cost estimate, and 

furthermore specifies criteria for conducting the cost evaluation. In addition, the final rule at § 

122.21(r)(13) requires the study must be externally peer reviewed. Finally, at § 125.98(f), the 

final rule states that the proposed permit must include the Director’s proposed entrainment 

determination. As such, the site-specific cost estimates, potential effects to electricity rates and 

reliability, and other information that may be considered by the Director when determining BTA 

will be subject to public scrutiny. As noted by the commenter, site-specific assessments of costs 

and benefits can vary, EPA is not required to do so, and therefore did not evaluate information 

on that scale in establishing the final rule. EPA is aware that the use of site-specific cost 

estimates may be overstated, as historically facility developed cost estimates do not appropriately 

represent the incremental costs of compliance. EPA expects the peer-review and other 

requirements in the rule discussed above will ensure facility level cost estimates are properly 

determined. 

With respect to sensitivity analyses, EPA disagrees that formal, quantitative analyses are 

required, according to guidance from OMB for regulations with a total cost under $1 billion. 

(See OMB Circular A-4, DCN 10-3266.) Instead, EPA has discussed the uncertainties and 

limitations in its analyses; for example, see the TDD. EPA identified the major cost drivers of the 

rule, and these uncertainties would not have changed the outcome of the final rule decisions. 

EPA has not identified any other parameters upon which to conduct a sensitivity analysis, and 

the commenter did not provide any suggestions. Therefore, even if EPA had conducted 

additional sensitivity analyses, the EPA does not expect results of such analyses would have 

changed the outcome of the final rule decisions. 

Comments Specific to Cost

Industry commenters generally stated that the proposed rule was overly expensive (some asserted 

costs were prohibitive), that costs were underestimated, compliance costs could lead to higher 

costs for consumers, or could lead to facility closures, and all without a commensurate increase 

in benefits. Some commenters provided facility-specific cost estimates for technology 

installations. These commenters also stated that these cost would be incurred at facilities where 

the facilities believe no adverse environmental impacts are occurring. Commenters also stated 

that EPA neglected to include costs for entrainment controls in its analysis. Similarly, these 

commenters claimed that facilities with certain technologies or intakes in certain locations would 

not require any action and that the national-scale analysis used by EPA masks these site-specific 

details. Other commenters added that effects outside of 316(b) affect water quality and aquatic 

organisms and would not be reflected in EPA’s analysis. Some commenters asked EPA to clarify 

that “social costs” include capital costs, monitoring and O&M. 

Essay 15 95 
Some commenters noted that there are significant costs associated with compliance for other 

rules. Other commenters noted that EPA’s analysis does not include sufficient data on the 

category of “other industries” and this category should therefore be excluded from the regulation. 

Some environmental commenters stated that even the highest cost options examined resulted in 

nominal increases on a per-household basis. Environmental commenters also noted that EPA has 

not considered certain categories of costs, such as the costs associated with once-through cooling 

and the economic impacts of fish kills. Another environmental commenter stated that oncethrough cooling amounted to a subsidy for industrial facilities. 

As described in the preamble, EA and Essay 21, EPA has conducted a thorough analysis of the 

incremental costs to comply with today’s final rule. That is, the costs are those that EPA 

estimates facilities would incur in addition to existing costs to comply with today’s rule. EPA 

notes that many commenters did not provide a detailed description of their cost estimates, 

making it impossible for EPA to evaluate some commenter’s submittals. To the extent facilities 

and vendors provided detailed costs, EPA considered such data in combination with the rest of 

its record for estimating costs for the finale rule. As discussed above, facility-level cost estimates 

are often higher than EPA’s cost estimates because they do not properly reflect the incremental 

costs of compliance. For example, a facility that already employs modified traveling screens with 

smooth mesh and fish friendly buckets would not be costed for installation of new modified 

traveling screens. In some instances the data provided by commenters was not comparable due to 

inconsistent analytical methods provided in comments such as interest rates, annualization terms, 

useful life of equipment, and commenter assumptions regarding labor hours and compliance 

monitoring EPA’s final rule cost estimates are based on all available data, including 

appropriately documented cost data provided by commenters. Therefore EPA disagrees that the 

costs are significantly understated, and in light of the cost driver sensitivity analysis discussed 

above, any small changes in costs would not result in a different decision. EPA also disagrees 

that the costs are unreasonable, as described in the preamble, the EA, and above. Specifically, 86 

percent of regulated facilities will incur compliance costs of less than 1 percent of revenue. On 

average, for a typical U.S. household, the final rule will result in an annual cost of $1.03 per 

household. See preamble Section IX for additional analyses demonstrating the costs of the final 

rule are reasonable and affordable. 

EPA estimated incremental costs for the regulatory options evaluated for today’s final rule. For 

regulatory options that included a specific technology basis for both impingement and/or 

entrainment, EPA estimated incremental costs for those facilities to come into compliance. The 

regulatory option ultimately selected for today’s final rule includes performance standards for 

impingement mortality and a site-specific determination of entrainment requirements. Because 

determinations of BTA for entrainment are to be made by the Director on a site-specific basis, 

EPA has no way to predict the outcome (and therefore incremental costs) of these site-specific 

permit proceedings. As is common with EPA national technology based regulation development, 

costs associated with site-specific requirements are not estimated as rule costs because, in 

absence of nationally applicable technology based regulations, permitting authorities are already 

required to determine technology based requirements on a best professional judgment basis, and 

facilities are already required to meet such requirements. Therefore this rule would not impose 

any incremental compliance costs. The rule does require certain studies and information to be 

submitted, and the rule does include the costs for these activities. The costs for the final rule 

Essay 15 96 
therefore include incremental costs associated with the impingement mortality performance 

standard and incremental costs associated with the site-specific entrainment process including 

characterization study requirements. Because the Director will consider various factors including 

costs and impacts in determining site-specific BTA for entrainment, the commenters concerns 

will be most appropriately addressed on a site-specific basis. Nevertheless, EPA did estimate 

costs for various entrainment technologies. For illustrative purposes, EPA analyzed two 

hypothetical outcomes for the proposal (76 FR 22211). 

EPA disagrees with the comments regarding “other” industries. EPA established a model facility 

costs analysis, and has assigned each model manufacturing facility a weight of greater than one; 

this modeling approach ensures all in-scope facilities are counted in EPA’s analysis. EPA notes 

that the Phase III rulemaking, the 2011 proposed rule, and the 2012 NODA all provided 

opportunities for comment and data. EPA specifically solicited comment on the “other 

industries.” EPA did not receive new data upon which it could consider additional model 

facilities. EPA has therefore established a reasonable approach to conducting the analysis and 

has made a reasonable effort to represent all in-scope facilities. 

Benefits

Some industry commenters stated that benefits were overstated in the proposed rule. Others 

stated that EPA’s assessment of benefits in the proposed rule was incomplete, as the stated 

preference survey had not yet been conducted in all regions nor had the analyses been completed, 

thereby depriving the public the opportunity to comment on the analysis. Some commenters 

provided site-specific estimates of benefits projected to be realized through compliance with the 

rule. 

A state commenter argued that the complexity of EPA’s benefits analysis would be unlikely to 

be repeated at the state level, making it difficult for a Director to pursue closed-cycle cooling as 

an entrainment control technology at a site-specific level. 

Some environmental commenters (including Riverkeeper) stated that EPA has underestimated 

the benefits of closed-cycle cooling. Similarly, these environmental commenters noted that 

EPA’s benefits analysis is incomplete, as it does not include the value of entrainment reductions 

for many facilities under some options. Environmental commenters added that EPA cannot 

ignore the results of the stated preference survey, however preliminary they may be. 

Environmental commenters also stated that EPA should weigh impacts to threatened and 

endangered species as significant, given that the loss of even a single individual can be a 

significant effect on the remaining population. 

As described in the preamble, BA and Essays 70, 71 and 73 through 78, EPA has conducted a 

thorough analysis of the benefits as a result of today’s final rule. EPA disagrees that the benefits 

are overestimated, as described elsewhere, and EPA notes that commenters did not explain how 

EPA had overstated benefits. Because EPA did not calculate benefits for the final rule on a sitespecific basis, it is not possible to directly compare EPA’s analysis with facility-specific values 

submitted by some commenters. Finally, as discussed above, EPA disagrees that only monetized 

benefits should be considered. 

Essay 15 97 
One commenter argued that EPA should use a market-based approach (such as cap and trade), as 

this would likely maximize the net benefits. The commenter added that, in the absence of such an 

approach, EPA must weigh the advantages and disadvantages of a site-specific approach. 

EPA disagrees that a trading program would maximize net benefits. EPA notes that section 

316(b) of the Clean Water Act intends to minimize the adverse environmental impact associated 

with cooling water intake structures. EPA considered a trading program in response to comments 

in the now remanded Phase II rule (see Phase II RTC at 316bEFR.034.027). The premise is that 

such a program must result in environmental performance within a watershed that is comparable 

to the reductions of impingement mortality and entrainment that would otherwise be achieved 

under the requirements established at § 125.94. To this end, EPA expected approval would only 

occur for those trading programs which allow trades within individual watersheds and trade for 

numbers of the same species. However, such an approach would not minimize AEI, because 

under such a program there is no incentive or requirement for a group of facilities (involved in 

the trade) to do any more than the bare minimum. Such an approach does not maximize net 

benefits because it neither maximizes benefits nor reduces compliance costs more than EPA’s 

final rule approach. Under EPA’s approach to the final rule, the facility has seven compliance 

alternatives for IM. The first four alternatives are based on pre-approved technologies or superior 

performing technologies, such as CCRS or intake velocity. Facilities utilizing these technologies 

are already achieving some of the highest reductions in IM possible, and their benefits are likely 

close to maximum. Under these alternatives compliance is already streamlined, such as no 

requirement for biological compliance monitoring. The costs to these facilities are already 

minimal. Under another two of the compliance alternatives (modified traveling screens and 

systems of technologies), the technologies selected by the facility must undergo an optimization 

study. Because the facility will be optimally operating these technologies, the highest reductions 

in IM possible are already obtained. Again, the costs are already reduced as there is no 

requirement for biological compliance monitoring or other monitoring in perpetuity. As a result, 

EPA’s final rule has minimal costs for the roughly 99 percent of facilities expected to choose one 

of these six compliance alternatives, and the highest possible performance is obtained. Trading 

would require biological monitoring by each facility, an endeavor cited as expensive by 

commenters, and this burden alone makes it unlikely such an approach could come close to the 

net benefits of EPA’s selected approach. EPA further notes a trading program that includes other 

stressors such as habitat alteration, dredging, coastal development, overfishing, industrial 

pollution, nutrient pollution, wastewater runoff, and climate change might not satisfy all 

requirements because these types of trades introduce comparability and implementation 

challenges that would be difficult to overcome. EPA also questions whether such a program 

would be consistent with EPA’s Water Quality Trading Policy. Thus, it is questionable whether 

such a program could even meet the requirements for approval. EPA agrees that there are 

advantages and disadvantages to each approach considered in the rulemaking, and has done so. 

See Section VI of the preamble for EPA’s rationale for decision-making. 

Other Elements of BTA

Variances

Other commenters stated that EPA should create a variance for economic considerations on a 

site-specific basis, asserting that such variances were permitted by the U.S. Supreme Court in 

Essay 15 98 
Entergy, and should then provide detailed guidance to Directors on the decision criteria to use in 

considering costs and benefits. Other commenters suggested variances such as a cost-cost test or 

fundamentally different factors to avoid unreasonable results. Some commenters argued that 

EPA should allow a site-specific cost-benefit test to determine compliance with the final rule, 

including specific guidance to the Director to reject any entrainment technology whose costs 

exceeded its benefits or that did not maximize the net benefits. These commenters noted that 

such a site-specific determination would provide the greatest flexibility and maximize the ability 

to consider costs and benefits. Some commenters stated that the impingement mortality 

requirements should also be subject to a cost-benefit test. Other commenters argued that if 

certain cost (or feasibility) criteria were not met, a facility should not be obligated to examine 

certain compliance options in detail. 

EPA disagrees with these comments. See § 125.31(d) for factors that may be considered if a 

facility is fundamentally different, as well as those factors that may not provide a basis for a 

variance. Under § 125.31(b)(3), a request for less stringent requirements may be approved only if 

compliance would result in a cost wholly out of proportion to the costs considered during 

development of the standards; or non-water quality environmental impacts more adverse than the 

impact considered during development of the standards. EPA finds that, for the IM requirements, 

neither of these conditions would occur. While none of the IM compliance alternatives will result 

in incremental non-water quality environmental impact that are adverse, EPA notes the rule at § 

125.94(c)(12) already addresses low CUR units that may be important for grid reliability. EPA 

has identified technologies for IM that are demonstrated, achievable, and affordable. EPA’s 

flexible approach includes 7 compliance alternatives, including credits for existing technologies 

and intake location. EPA’s final rule also includes a de minimis provision where rates of 

impingement or so low as to make additional controls unwarranted. As a result, the compliance 

costs for the final rule are less than those at proposal, and commenters did not provided any data 

demonstrating compliance costs for IM at any facility are wholly disproportionate to EPA’s 

proposal costs. (EPA notes that a permitee’s ability to pay is not an allowable basis for a 

variance.) With respect to comments pointing out that the Phase II rule had such provisions such 

as cost-cost, EPA notes the Phase II rule also had technology requirements for entrainment, that 

the costs of these technologies is considerably higher than the costs of today’s final rule. This is 

not the case here. In consideration of all of these features of the final rule, EPA concludes that an 

additional variance provision is unnecessary. 

Availability and Flexibility of Rule Requirements

Many commenters stated that the proposed rule only provided for two compliance alternatives 

for minimizing impingement mortality -- an impingement performance standard and a maximum 

intake velocity standard -- and that achievement of these standards were not available at all 

facilities. Commenters requested that EPA identify pre-approved technologies for impingement 

and that these technologies have minimal permit or monitoring requirements associated with 

them. Other commenters requested that the rule provide flexibility for facilities with multiple 

intake structure configurations. Other commenters noted that EPA should consider previous 

reductions in impingement in evaluating impingement mortality performance at a particular 

facility. 

Essay 15 99 
EPA disagrees that the performance standard is not available at all facilities. EPA notes many 

commenters mistakenly assumed modified traveling screens with a fish return were required by 

the rule. Other commenters asserted that retrofit CCRS was the only way to meet the 

performance standards. As discussed in the NODA (77 FR 34319) and addressed in Essay 24, 

neither is not the case. EPA also made it clear in the proposal and NODA that consideration of 

other technologies, including intake location and alternative technologies, were intended as an 

integral part of the IM performance standard; see 77 FR 34321 – 5. EPA’s record shows there are 

many IM technologies (as well as combinations of technologies) that are demonstrated. Based on 

EPA’s technical survey, site visits, and other information in the record, EPA concludes that one 

or more technologies are available for every facility. While commenters provided data and 

examples where one or more technologies may be more costly or difficult to install at a particular 

site, none of the commenters provided data or identified a facility in which the IM performance 

standards could not be achieved. For the final rule, as discussed above the BTA standard for 

impingement mortality includes seven compliance options that, in addition to the impingement 

mortality performance standard, include pre-approved technologies as well as options for 

streamlined compliance. The alternative at § 125.94(c)(6) allows for consideration of other 

technologies resulting in previous reductions in impingement. In the permit application 

requirements at § 122.21(r)(6), the owner or operator must identify the chosen compliance 

method for the entire facility; alternatively, the applicant must identify the chose compliance 

methods for each CWIS. 

As noted, the final rule provides a number of compliance alternatives for meeting the 

impingement mortality standard. For example, the final rule at § 125.94(c) identifies three preapproved IM technologies (closed-cycle, design intake velocity of 0.5 fps which includes most 

wedgewire screens, and offshore velocity caps) for which there may be reduced permit 

application requirements and for which no biological compliance monitoring is required. The 

final rule further streamlines compliance for those facilities using the specific technology that 

forms the basis for the impingement mortality performance standard (modified traveling screens, 

see § 125.94(c)(5)). Another alternative at § 125.94(c)(6) includes conducting an optimization 

study for a “system of technologies” that achieves the required level of performance. A facility 

may demonstrate that its existing technology reduces the rate of impingement and therefore 

qualifies for a “credit” towards meeting impingement requirements as part of this alternative. 

Another commenter stated that national requirements would reduce the permitting authority’s 

burden, while providing a higher level of protection. EPA notes that the final rule establishes 

national standards for minimizing impingement mortality and entrainment. In the case of the 

standard for minimizing impingement mortality, there are seven different options, each has a 

clearly described information requirements for permit submittal and how to comply is either 

apparent or spelled out. As discussed above, in the case of the BTA standard for entrainment, the 

final rule establishes a framework for facilities to gather data, conduct studies, and obtain 

external peer review, along with a process by which the Director considers certain factors and 

establishes appropriate entrainment controls. EPA has reduced or streamlined the burden on 

facilities as compared to the proposed rule. For example, as noted above, the pre-approved 

compliance alternatives will greatly reduce monitoring costs, as well as simplify compliance and 

oversight by the Director. EPA agrees that each of these national standards reduce permit 

authority burden. 

Essay 15 100 
                                                            

 

Many commenters stated that EPA should determine if an adverse environmental impact is 

occurring before taking action. EPA has determined impingement and entrainment are the 

“adverse environment impact” of cooling water intake structures that its section 316(b) standards 

should address. Studies in EPA’s record show impingement and entrainment occur at CWIS of 

all types, sizes, and locations. Therefore all facilities with a CWIS have the potential for causing 

AEI. EPA disagrees that the presence of community- or population-level impacts is required 

before an AEI has occurred. This has been the EPA’s consistent position in prior rules and the 

Second Circuit in both Riverkeeper I and Riverkeeper II has sustained this position. See Essay 16 

for more detailed discussion. 

Some commenters state that the proposed rule (by not addressing entrainment) will engender a 

“race to the bottom” among states, contrary to the goals of the Clean Water Act. Another 

commenter stated that the proposed rule does not guarantee that impacts will be minimized. EPA 

disagrees and notes that the final rule has been structured in a way that provides facilities and the 

Director with the best possible tools to minimize impacts at each site, including addressing 

entrainment on a site-specific basis. In the case of the BTA impingement mortality standard, 

EPA based the standard on the performance of modified traveling screens. In the case of the 

BTA entrainment standard, EPA concluded there was no single, nationally available technology. 

Instead, the BTA standard establishes a framework for studies and information, along with peer 

review, and requires a site-specific proceeding in which the Director must evaluate certain 

factors. The EPA concluded that the site-specific proceeding mandated by the E standard will 

reflect, among other things, the variability between sites including species, geographical 

location, CWIS operation, technologies and practices already in place, and intake location. 

Many commenters stated that EPA appears to have identified 125 mgd as the flow threshold for 

the occurrence of adverse impacts and that any facility below that threshold should be presumed 

to employ BTA for both impingement and entrainment. Other commenters suggested that EPA 

conclude that all facilities withdrawing less than 125 mgd to be compliant with the rule, as the 

benefits of including these facilities in the universe of affected facilities would likely not justify 

the costs. Commenters noted that this would allow the Director to focus on higher impact sites, 

while still allowing some degree of site-specific requirements on an as needed basis. Other 

commenters stated that EPA has provided no evidence of adverse impacts at sites withdrawing 

between 2 mgd and 125 mgd. 

EPA disagrees with each of these comments and approaches. EPA’s analysis indicates that 

greater than 82 percent of impinged fish mortality across all facilities would be prevented by this 

rule at this threshold. EPA disagrees that it has not examined impingement and entrainment 

effects at facilities with flows under 125 mgd; EPA specifically collected studies during the 

Phase III rule and considered these studies in its development of the impingement mortality limit 

in the final rule.11 The record includes more than 40 studies from facilities with flows lower than 

50 mgd documenting IM at such facilities. EPA has defined adverse environmental impact as 

any impingement or entrainment (i.e., adverse impacts are not predicated upon flow), as noted in 

the preamble. Further, the industry questionnaire demonstrates that such facilities are twice as 

likely to have no controls in place for impingement or entrainment than are facilities with higher 

11 See 69 FR 68451 (November 24, 2004) and for a specific example, DCN 10-5554 for a study from a facility with 

a DIF of approximately 18 mgd and an AIF or approximately 7.5 mgd. 

Essay 15 101 
intake flows, especially those greater than 50 mgd. In addition, lower intake flow facilities both 

by themselves and in aggregate can have similar impacts to those of larger flow facilities as 

sizable numbers of fish are impinged by lower flow facilities. Moreover, site-specific impacts of 

lower flow facilities may be significant, particularly where threatened or endangered species are 

present. One state commenter argued that a focus on flow does not necessarily correlate to 

adverse impacts; for example, a facility withdrawing less than 125 mgd might be withdrawing a 

large percentage of the source waterbody. EPA agrees with the comment and notes that the 

Director may require a facility to submit additional permit information to address these 

scenarios, including, where not otherwise applicable, the information required, for example, at § 

122.21(r)(8)-(13). EPA’s selection of 125 mgd as a threshold is not the result of an assessment of 

biological impacts, but is (in part) an administrative cutoff to balance the Director’s need for data 

against the burden placed upon regulated facilities. 

EPA disagrees that costs do not justify the benefits of including lower flow facilities. Although 

smaller flow facilities constitute a larger proportion of the total number of the facilities regulated, 

the total compliance cost for these smaller facilities are only a small portion of the total 

compliance cost of the rule (for example, $23 million at a threshold of 50 mgd). See the TDD 

and Essay 14 for more information regarding thresholds, including cumulative impacts, low flow 

facilities that withdraw significant portions of a waterbody, and other impacts. These lower flow 

facilities, if not subject to the national standard, would still be subject to section 316(b) and thus 

would require BPJ permit requirements. Thus any perceived aggregate cost savings from setting 

the threshold higher is minimal. And because the costs are a small portion of the total 

compliance costs, and for all of the reasons stated above, the costs justify the benefits. 

EPA agrees that the Director must consider costs and benefits in establishing the entrainment 

requirements, irrespective of the 125 mgd flow threshold; this is required at § 125.98(f)(2)(v). As 

noted above, the 125 mgd threshold is not intended to be an indicator of impacts and the Director 

is authorized to require the additional studies to facilitate the BTA determination. 

A commenter also stated that EPA should determine that facilities meeting the 0.5 fps intake 

velocity threshold as meeting the entrainment requirements. EPA disagrees, noting eggs and 

other early life stages of larvae are nonmotile and have not developed an avoidance response, 

therefore a lower intake velocity is essentially irrelevant. See Essays 17 and 18 for more detailed 

discussion. 

Commenters stated that EPA should not promulgate entrainment standards at all, as they are 

burdensome, costly, subjective, and have a poor cost-benefit ratio. Some commenters also stated 

that a best professional judgment-based approach will lead to inconsistent application of 316(b) 

across the nation. As discussed above, EPA disagrees with these points. EPA’s record indicates 

that entrainment is a significant aspect of addressing adverse environmental impacts at cooling 

water intakes. EPA has not identified a single technology that is nationally available to address 

these impacts. EPA has, however, repeatedly stated that the lack of widely available technology 

for reducing entrainment mortality in no way suggests that entrainment effects are not important. 

On the contrary, the final rule establishes requirements to submit data and the framework for the 

process for the Director to determine the BTA for entrainment at each site. 

Essay 15 102 
Commenters also requested that EPA reconsider the implementation schedule for the rule such 

that a facility could address both impingement and entrainment at the same time, thereby 

preventing wasted expenditures. EPA agrees, see rule requirements for implementation schedule 

at § 125.94(b) and Essay 22. Some commenters argued for separate requirements for nuclear 

facilities; see Essay 18. EPA disagrees, noting that commenters have not submitted data 

supporting why nuclear facilities need separate requirements; see TDD Chapter 6 and Essays 14 

and 19 for EPA’s consideration of subcategories. Some commenters argued in favor of certain 

flow thresholds for triggering compliance. EPA disagrees, as discussed above for the 125 mgd 

threshold; also sees TDD, preamble, and Essays 14 and 19 for more information. A commenter 

stated that EPA should “grandfather” existing facilities and instead focus on new facilities. EPA 

disagrees, see Essay 10 for legal authority and preamble section VI Basis for rule; also see Essay 

14. Another commenter stated that EPA should not require major changes at the facility and 

drew a comparison to BACT for air emissions regulations; EPA disagrees, noting that 316(b) of 

the Clean Water Act has statutory requirements different than the Clean Air Act. See preamble 

section III for legal authority and Essay 10. 

Some commenters noted that several states have an existing 316(b) program, obviating the need 

for national requirements. For example, one commenter noted that California has already begun 

a state policy to eliminate once-through cooling at coastal facilities. As described in the 

preamble, EPA is aware of this and recognizes that some states have invested significant time in 

developing NPDES permits and has provided some flexibility in the final rule to incorporate that 

past effort into the new national requirements. Specifically, § 125.90(c) explicitly states that 

states can adopt more stringent controls than required by Federal Law, and § 125.98(g) in 

today’s rule acknowledges the work already done by States in ongoing permit proceedings. In 

response to the comment that a State should not have achieve environmental performance 

comparable to those that would be achieved under § 125.94, EPA disagrees. While EPA is giving 

significant flexibility to permitting agencies at the State level to determine how and what each 

facility must protect and monitor, it is appropriate for EPA to set uniform national performance 

standards. Other concerns raised by the commenter are addressed by EPA’s revised 

implementation schedule, which marries the timeline for impingement controls and entrainment 

controls. 

Other industry commenters suggested other revisions to the proposed rule, including (for 

example, requirements that vary by waterbody type, requirements that vary for manufacturers 

and other facilities with a low intake flow, consideration of the benefits of once-through cooling, 

and accounting for variability. The EPA disagrees with commenters’ suggestion that a sitespecific approach for impingement is warranted, most notably because there are controls for IM 

that are available, demonstrated, and achievable; this is not the case with entrainment. See 

preamble for further discussion. EPA considered many different subcategories including fuel 

type, source waterbody type, industrial type, cooling water flows, intake location, age of 

generating unit, and others; see TDD for further discussion. EPA concluded that no 

subcategorization was necessary or appropriate for the final rule, because there are controls for 

IM that are available, demonstrated, and achievable. EPA considered the same approaches to 

subcategorization for E requirements, but there are no demonstrated and available high 

performing technologies for entrainment, and EPA concludes that the different factors 

considered for subcategorization does not change this finding. Also see Essay 19. 

Essay 15 103 
One commenter stated that EPA has inherently acknowledged in its support documents that 

regional differences in biology preclude the possibility of national-level requirements. EPA 

disagrees. EPA’s record shows that BTA for IM is achievable on a national scale at all facilities. 

See Essay 16A for full discussion of the variability and applicability of the IM performance 

standards. The technologies forming the basis for the final rule’s performance standards are 

available, feasible, and demonstrated (see preamble). Another commenter stated that national 

requirements should not be developed for waters that do not cross state lines; EPA disagrees, 

noting that the Clean Water Act (and consequently, section 316(b)) extends to waters of the 

United States irrespective of State lines. One commenter stated that the proposed rule would 

interfere with the operation of vessel traffic and dock operations. EPA agrees in part, for 

example, some types of screens in some waterways may interfere with boating. EPA disagrees 

that the IM standard is not achievable, first noting that the facility in question already has an 

intake structure and is able to operate the facility despite dock and vessel traffic. EPA notes that 

other facilities also have navigational traffic to contend with, and EPA has accounted for 

additional costs incurred as a result of navigational traffic as one of several types of site-specific 

factors that make technology upgrades a more “difficult” level of retrofit; see Chapter 6 in the 

TDD, identifying additional costs for “difficult” level installations. Further, the final rule offers 

seven compliance alternatives for IM, allowing the facility to take into account such 

consideration in order to accommodate facility-specific circumstances. 

Another commenter stated that EPA should integrate consideration of thermal effects into the 

rule framework. Other commenters noted the secondary effects associated with implementation 

of section 316(b) controls in reducing thermal discharges from industrial sites. EPA agrees that 

thermal impacts can be an important consideration but has not included any specific 

considerations in the final rule, aside from a requirement to consider thermal effects in a 

facility’s permit application materials. Thermal impacts are typically addressed under section 

316(a), a different part of the Clean Water Act. EPA notes that any associated reductions in 

thermal discharges may well be a factor in permitting determinations under section 316(a). 

Reduced thermal discharges was not a consideration in the EPA’s determination of national BTA 

standards for E, because EPA did not identify any technology for E that was demonstrated, 

available, and achievable. Therefore, EPA did not need to consider reduced thermal discharges 

when comparing different technologies. 

Some commenters stated that EPA has not properly accounted for aquatic species in the Pacific 

Ocean or other locations. EPA disagrees; as noted in the preamble and Essay 16A, EPA 

reviewed many studies with impingement mortality data in developing the final rule and found 

no reason to subcategorize facilities by these assemblages for the purposes of a national rule. In 

fact, many of the species in either the Atlantic or Pacific locations exhibit similar physiological, 

ecological and behavioral traits and are therefore a reasonable surrogate for examining 

impingement and entrainment effects. Some commenters provided data from facilities 

withdrawing cooling water from the Pacific Ocean, and EPA they employ the same technologies 

(including traveling screens, offshore velocity caps, and low intake velocity) that EPA used in 

setting the final rule’s performance standards. Indeed, the record from the Phase II rulemaking 

shows that approximately 95 percent of the species of fish are capable of swimming away from 

an intake velocity of 0.5 feet per second; see DCN 2-028A. As discussed above, the technologies 

forming the basis for the final rule’s performance standards are available, feasible, and 

demonstrated (see preamble). 

Essay 15 104 
Essay 16: Requirements for Impingement and Entrainment

Introduction

As described in the preamble to the final rule, EPA has developed a final rule that establishes 

“best technology available” standards for cooling water intake structures that minimize adverse 

environmental impacts. Specifically, the final rule establishes BTA standards for reducing 

impingement mortality and entrainment, the adverse environmental impacts that EPA identified 

as associated with cooling water intake structures. First, the rule establishes a BTA impingement 

mortality standard that provides seven different alternatives for complying with the standard. 

Second, the rule establishes a BTA standard for entrainment that requires the determination of 

required entrainment reduction measures in a structured site-specific permitting proceeding. The 

BTA standard for entrainment requires that certain prescribed factors must be considered in the 

decision and must reflect the maximum reduction in entrainment warranted after consideration of 

relevant. EPA introduced the framework for entrainment decision-making in the proposed rule 

and, based on public comments and additional analysis by EPA, revised this framework as 

explained in a subsequent Notice of Data Availability (NODA). This essay addresses specific 

comments on adverse environmental impact, and the requirements associated with today’s BTA 

standards. Please refer to Essay 15 for information on EPA’s approach for determining BTA for 

existing units and Essay 20 for EPA’s approach to the requirements for new units. 

Adverse Environmental Impact (AEI)

Section 316(b) of the Clean Water Act requires that “the location, design, construction, and 

capacity of cooling water intake structures reflect the best technology available for minimizing 

adverse environmental impact.” A number of industry commenters stated that EPA has not 

demonstrated that adverse impacts are occurring, suggesting that there is no need for a 

regulation. These commenters also stated that EPA has not demonstrated that the current level of 

impacts from impingement and entrainment are affecting aquatic organisms at the population 

level. Other commenters added that some species exhibit high rates of natural mortality, which 

may lead to a lack of impacts due to impingement of individuals of these species. Other 

commenters argued that EPA has historically used a population-based approach and should 

continue to do so. Some commenters called on EPA to define AEI, including acknowledging that 

some impingement is not an adverse impact (e.g., impingement of nuisance species or stocked 

fish). Some commenters stated that EPA has cited examples of impacts from large facilities and 

extrapolated these impacts to all facilities. Some commenters argued that the proposed rule goes 

beyond minimizing AEI and is inconsistent with the Supreme Court’s interpretation of BTA. 

Some commenters argued that the rule should exclude stocked fish from the definition of 

impingement. 

A commenter argued that EPA should expand the universe of affected organisms to include all 

biota. Riverkeeper also stated that impacts should not be based solely on the numbers of 

individuals impinged or entrained, as this may not accurately reflect the biological implications. 

State commenters argued in favor of both industry’s and Riverkeeper’s interpretation of AEI. 

One commenter stated that EPA should allow the Director to assess whether AEI is occurring, 

Essay 16 105 
while another called upon EPA to clearly define AEI and provide guidance to determine when a 

waterbody is being adversely affected. 

With respect to comments on defining AEI, EPA has not changed its views about what 

constitutes AEI from those explained in the Phase I rule, the remanded Phase II rule, the Phase 

III rule and the proposal to today’s final rule. See 66 FR 65289-97 (December 18, 2001) and 

316bNFR.029.013 from the Phase I Response to Comment document (DCN 3-0091); 69 FR 

41612 (July 9, 2004); 71 FR 35019 (June 16, 2006); and 76 FR 22196 (April 20, 2011). In those 

preambles, EPA discussed what are the adverse environmental effects that the 316(b) standards 

are designed to minimize. 

In the Phase I rule, EPA established a framework that defined AEI as the impingement or 

entrainment of individual organisms, regardless of considerations of population effects, natural 

mortality, or compensatory reserve. (See, e.g., 66 FR 65289 [December 18, 2001], which states 

“EPA does not agree that adverse environmental impact associated with cooling water intake 

structures is solely a population-based phenomenon” and 66 FR 65285 “EPA does not believe 

that a population approach makes sense for new facilities.”) Upon challenge by industry, the 

Second Circuit agreed in Riverkeeper I, stating: 

“We think that the EPA’s focus on the number of organisms killed or injured by cooling 

water intake structures is eminently reasonable. See Final Rule, 66 Fed. Reg. at 65,262­

63, 65,292. As discussed above with respect to restoration measures, Congress rejected a 

regulatory approach that relies on water quality standards, which is essentially what 

UWAG urges here in focusing on fish populations and consequential environmental 

harm.” 

EPA continued to use this approach for existing facilities in the Phase II rule (“Similarly, based 

on the analyses and for the same reasons set forth in the preamble to the new facility rule [66 FR 

65256, 65291–65297], EPA has selected reductions in impingement and entrainment as a quick, 

certain, and consistent metric for determining performance at Phase II existing facilities.” 69 FR 

41586 [July 9, 2004]). Upon challenge by industry in Riverkeeper II, the Second Circuit again 

supported EPA’s approach to defining AEI: 

“As did the industry petitioners in Riverkeeper I, PSEG argues that the EPA arbitrarily 

defined AEI to include any loss of or harm to aquatic organisms due to impingement 

mortality and entrainment rather than only more severe “population-level effects.” [...] 

We are not persuaded by PSEG’s arguments. 

We agree with the EPA that the Phase II Rule is based on substantially the same record 

evidence of impingement mortality and entrainment relied upon in promulgating the 

Phase I Rule and that we rejected substantially the same arguments advanced here by the 

industry petitioners in Riverkeeper I, 358 F.3d at 197 (“The EPA considered all of the 

factors that UWAG now raises, and we are inclined to defer to the EPA’s judgment of 

how best to define and minimize ‘adverse environmental impact.’” (internal footnote 

omitted)). Riverkeeper I thus controls this issue.” 

EPA again followed this approach in the Phase III rule (see 69 FR 68461, November 24, 2004). 

Essay 16 106 
Commenters failed to provide new information or basis for changing EPA’s position regarding 

AEI and the direct link between impingement and entrainment. EPA has concluded that it is 

inconsistent with “minimizing adverse environmental impacts” to adopt standards based on 

ensuring only against the most drastic consequences – decline and destruction of fish populations 

– rather than preventing these in the first instance through the reduction of impingement and 

entrainment. As stated, EPA has no basis for changing its long-held approach in today’s final 

rule based on a sound scientific basis sustained in multiple legal reviews. As discussed in the 

preamble, EPA has identified a clear need for addressing impingement and entrainment at 

cooling water intakes and the definition of AEI in today’s final rule is consistent with the rule 

framework and EPA’s historical treatment. EPA has not included any further definition or 

guidance for AEI in the final rule, as it is not necessary; the rule recognizes that AEI may be 

occurring at all intakes and establishes an appropriate framework for facilities to address these 

impacts. 

With respect to comments stating that AEI should be defined as all organisms, including all 

biota, EPA disagrees. The Agency focus of section 316(b) requirements is on all life stages of 

fish and shellfish, and as discussed above commenters did not provide new data or information 

why the Agency should change this approach. Impingement and entrainment are the primary (but 

not only) indicators of AEI under today’s rule, as they are the most easily measured impacts. 

Because EPA acknowledges that other organisms may be a concern on a local basis, the final 

rule provides the Director with significant discretion to identify and address site-specific 

problems for other categories of biota. At § 122.21(r)(11), the permit application must provide a 

discussion (with quantification and monetization, where possible) of any other benefits expected 

to accrue to the environment and local communities, including but not limited to improvements 

for mammals, birds, and other organisms and aquatic habitats. The definition of all life stages of 

fish and shellfish at § 125.92 gives the Director discretion to exclude nuisance species from 

being considered for impingement and entrainment requirements. The BTA provision at § 

125.94(c)(9) specifically addresses fragile species and other aquatic organisms in addition to fish 

and shellfish, and a provision at § 125.94(c)(8) specifically addresses additional protections for 

shellfish. EPA also disagrees that, in describing the impingement and entrainment effects at 

some facilities, it has extrapolated the impacts of large facilities across the affected universe. The 

examples provided in the preamble showcase facilities that impinge and entrain large numbers of 

organisms as a way to demonstrate the need for the regulation. EPA also disagrees that it has no 

data for facilities with a DIF less than 50 mgd. Some commenters have insisted this is this case 

despite studies available in the public record since Phase I, where EPA’s record includes counts 

of impingement at 5 facilities, one of which was under 20 mgd DIF (DCN W-00-03). The record 

for today’s final rule includes more than 40 biological studies from Phase III facilities 

(manufacturers) alone. In calculating the benefits associated with the rule (i.e., the reduction in 

the number of age-one equivalents impinged and entrained), EPA used a large number of studies 

from a variety of facilities (including small power plants and manufacturers) to derive an average 

value for various ecoregions; see the preamble and EEBA for more information. EPA disagrees 

that its definition of AEI is inconsistent with the Supreme Court’s view of BTA; refer to Essay 

15 and the preamble for additional discussion on EPA’s approach to BTA. 

With respect to comments suggesting that stocked fish be excluded from the definition of 

impingement, while the rule permits the Director to waive permit applications requirements for 

certain facilities located on waterbodies where the fisheries are stocked, the rule does not exempt 

Essay 16 107 
such facilities from impingement and entrainment requirements. EPA adopted this provision not 

as a means of excluding certain organisms, but rather recognizing the practical matter of 

conducting biological assessments that will soon be unrepresentative or their value negated by 

stocking and significantly adjusting the population in that waterbody. With respect to simple 

enumeration of impinged or entrained organisms, EPA also agrees that this approach is not 

always reflective of adverse impacts. For example, mortality of a single threatened or 

endangered organism may be significant. 

With respect to comments stating that EPA should account for past organism losses, EPA 

disagrees that assessments of impingement should account for past losses; it is inappropriate to 

consider additional permit requirements based on events that occurred in the past in an attempt to 

“make up ground.” Additionally, even if EPA agreed with this concept, EPA has little 

confidence that it would be able to accurately calculate the effects of past impingement losses on 

current abundances of organisms (especially when the abundance is also affected by other 

factors, such as fishing pressure, natural disasters, several decades of industrial operations, etc.), 

making it nearly impossible to determine an appropriate level of response. 

Impingement Requirements

Commenters provided information on a wide variety of topics related to impingement mortality 

requirements. 

Riverkeeper advocated basing the rule on closed-cycle cooling or reduction of intake velocity, 

which they state are more protective measures than the numeric limit. Riverkeeper also opposed 

providing additional means of complying with the impingement mortality standard that EPA 

described in the June 11, 2012 NODA. Many industry commenters argued in favor of a sitespecific approach to addressing impingement, noting that this would be consistent with the logic 

for addressing entrainment on a site-specific basis. This would also allow for the greatest degree 

of flexibility and options for the affected facilities, adding that this has been EPA’s historic 

approach for addressing impingement. Some state commenters also favored a site-specific 

approach. These commenters also stated that a site-specific approach would allow consideration 

of waterbody-specific concerns. One commenter provided a framework for determining BTA. 

Riverkeeper argued that a site-specific approach for impingement mortality would be less 

protective, as they expect many facilities will claim that they can’t meet the standards, delay 

permit proceedings, or otherwise overwhelm permit writers. Riverkeeper also stated that 

assessments of impingement should account for past organisms losses, which would artificially 

lower the present-day abundance of organisms. Some state commenters favored the limited use 

of a site-specific approach for impingement (e.g., in cases where closed-cycle cooling is a likely 

solution), but otherwise considered the approach to be too burdensome. 

Commenters were also concerned that many facilities would be unable to meet either of the two 

compliance options in the proposed rule, leaving no options for compliance and forcing facilities 

to install closed-cycle cooling to comply with impingement requirements. Commenters stated 

that a site-specific approach should be used if a facility can demonstrate that the national 

impingement mortality limit is not feasible. Commenters also stated that the rule assumes that no 

facility currently exhibits BTA. Commenters also noted that Ristroph screens have not been 

demonstrated as effective at all sites. Some commenters argued that EPA should eliminate the 

Essay 16 108 
numeric standard (and utilize a site-specific approach) or make the numeric standard a 

performance goal. These commenters advocated that a facility that installs a proven technology 

and demonstrates that it is operating the technology properly should be deemed to meet 

impingement requirements. Riverkeeper argued that facilities should be required to install 

multiple technologies to ensure that BTA is achieved. Some state commenters favored the 

numeric impingement limit, as well as some degree of monitoring to ensure that the technology 

is properly operating. Some state commenters favored the concept of combining compliance 

approaches. 

Other commenters argued in favor of identifying pre-approved technologies, including closedcycle cooling, velocity caps, cooling impoundments, and offshore wedgewire screens, as well as 

other developing technologies (Geiger screens, WIP screens, Hydrolox screens, etc.). Industry 

commenters opposed requiring that facilities employ a closed-cycle cooling system or achieve a 

0.5 fps intake velocity from being required to install modified traveling screens. Commenters 

also advocated that an intake should not be limited to exclusively supplying a unit with makeup 

water, which would exclude fire water or other uses. Several commenters also favored creating a 

process by which future technologies could become pre-approved. 

Similarly, industry commenters stated that EPA should include streamlined options in the final 

rule and favored the concept of identifying specific operating parameters and reducing the 

monitoring requirements. One commenter requested that EPA develop a database of technology 

performance for specific sites. Some commenters also noted that, for some facilities, there may 

be relatively few operational parameters that can be tested or fine-tuned, limiting the feasibility 

of a streamlined compliance alternative. Riverkeeper opposed the use of streamlined compliance 

alternatives, stating that it may allow facilities to be deemed to meet impingement requirements, 

while not achieving any actual improvement. Riverkeeper also opposed reduced monitoring 

under a streamlined compliance alternative, noting that it eliminates the only source of data that 

can confirm the continued performance of a technology. Some state commenters favored a 

streamlined compliance alternative. Commenters provided a wide variety of comments on the 

study requirements for a streamlined compliance alternative, ranging from eliminating the study 

entirely to arguing that the study would be challenging to conduct to agreeing with the general 

content of the study described in the NODA. Commenters also provided information on the 

various components of an intake technology, including features that can be optimized to 

maximize impingement survival. Commenters stated that facilities employing pre-approved 

technologies should not be subject to any monitoring requirements. 

Some industry commenters stated that the rule should also include a provision for facilities that 

exhibit very low levels of impingement (i.e., de minimis), in part because the numeric standard 

could penalize facilities with historically low levels of impingement. Some commenters also 

argued that the standard for de minimis should not be determined at a national scale, but left to 

the Director. Commenters also noted that the costs to install impingement controls may greatly 

outweigh the benefits of saving a few fish. Riverkeeper opposed the de minimis provision, noting 

that an annual threshold could mask significant short-term impacts. Some state commenters 

favored a de minimis provision, but called on EPA to provide a threshold in the final rule. 

Commenters argued that the final rule should permit “credit” towards meeting impingement 

mortality requirements for several categories of technologies. First, credit could be given for 

Essay 16 109 
flow reduction, such as closed-cycle cooling, operational measures, unit closures or retirements, 

variable speed pumps, or reduced capacity utilization. Second, credit could be given for 

technologies that reduce the rate of impingement (as opposed to the impingement mortality rate), 

such as barrier nets, behavioral technologies (e.g., lights, air bubble curtains, etc.), or intakes 

located in a less biologically-active area. One commenter suggested that EPA’s example of 

calculating credits was flawed. Some commenters (including Riverkeeper) stated that only the 

actual intake flow should be used as the baseline for flow credits, as this reflects “real” 

reductions in flow. One commenter said that EPA has essentially recreated the calculation 

baseline approach from the 2004 Phase II rule, but has not defined the term. Some commenters 

argued that EPA should not use an arithmetic average in calculating the appropriate credits, 

suggesting a proportional credit. One commenter also stated that the example equations provided 

in the proposed rule preamble were incorrect. Riverkeeper also stated that EPA should require 

long-term monitoring to verify any credits. Other commenters stated that EPA should clearly 

define a calculation baseline, as was used in the Phase II rule. 

Some commenters stated that EPA should include provisions for a fundamentally different 

factors (FDF) variance. 

Industry commenters also argued that the framework for impingement in the final rule should 

include considerations of cost-benefit or cost-cost tests, should eliminate the entrapment and 

barrier net provisions of the proposed rule, should consider closed-cycle cooling as compliant for 

impingement, should give credit to facilities that have already installed technologies (especially 

those that acted upon the Phase II rule by installing technologies), should allow previous 

determinations of BTA to remain valid and in effect, and should allow the facility to use existing 

studies as permit application materials. 

One commenter stated that EPA incorrectly concluded that nearly all eggs are entrained at a 

mesh size of 2 millimeters. 

One commenter stated that some facilities are faced with historically low water levels and may 

require booster or emergency pumps to be placed in the source water; these pumps typically have 

no screens. 

Option Selection

Refer to Essay 19 for the primary discussion of comments related to option selection. As 

described in the preamble, EPA has concluded that it should base the impingement mortality 

standard for existing units on the performance of modified traveling screens (e.g., modified 

Ristroph screens and equivalent modified traveling screens) with fish-friendly fish returns – the 

“best technology available” for minimizing impingement mortality). EPA refers to this BTA 

simply as modified traveling screens throughout this essay. While there are a number of 

technologies that may perform as well or better than traveling screens (including closed-cycle 

cooling), as detailed in the preamble, these technologies were not feasible or available on a 

nationwide basis and thus were not the “best technology available” for standard setting purposes. 

Moreover, the impingement mortality standard for existing units provides a number of 

alternatives, including some of these other technologies, for compliance with the standard. EPA 

based the BTA impingement mortality standard for existing units on the performance of 

Essay 16 110 
                                                            

traveling screens because EPA concluded that this technology is effective, widely available, 

feasible,12 and does not lead to unacceptable non-water quality impacts. 

With respect to comments that EPA should adopt a site-specific approach for impingement, as 

described in the preamble, EPA disagrees that it should adopt a national impingement mortality 

standard requiring the establishment of impingement mortality controls on a site-specific basis. 

EPA has established a national BTA performance standard for impingement mortality based on 

modified traveling screens. EPA concluded that, on a national basis, the performance associated 

with modified traveling screens is achievable, feasible and demonstrated. As such, EPA 

appropriately established a national BTA IM performance standard rather than a site-specific 

performance standard. This is in contrast to entrainment, where EPA did not identify a 

technology basis that is achievable, feasible and demonstrated. See preamble section VI for 

additional discussion. 

As to the commenter that provided a framework for determining BTA for IM on a site-specific 

basis, for the reasons specified above, EPA did not adopt a site-specific approach for determining 

BTA for IM. EPA did not adopt the framework wholesale but EPA notes that many of the 

elements in the framework are included in the final rule (e.g., pre-approved technologies, study 

of multiple alternate technologies, inclusion of a de minimis provision, etc.) 

Compliance Alternatives

As described in the preamble, there are seven compliance alternatives for meeting the 

impingement mortality requirements. One alternative is to comply with the impingement 

mortality performance standard. Three alternatives utilize pre-approved technologies for 

compliance. Three alternatives utilize a streamlined approach for permitting. Each of these are 

described in detail below. 

The alternative for complying with the impingement mortality performance standard (§ 

125.94(c)(7)) requires the owner or operator to demonstrate compliance with the numeric 

impingement mortality performance standard through biological monitoring. Under this 

alternative, the owner or operator has the flexibility to choose any technology, including a new 

or innovative technology, provided the compliance monitoring demonstrates the standard is 

achieved. 

The following pre-approved technologies will comply with today’s rule and are associated with 

minimal monitoring and reporting of operational and/or design parameters to demonstrate 

compliance. These technologies are (the numbering reflects the numbering in § 125.94(c)): 

operating (1) a closed-cycle recirculating system; (2) a cooling water intake structure that EPA or 

the State NPDES permitting authority determines has a design maximum through-screen intake 

velocity of 0.5 feet per second; or (4) an existing offshore velocity cap. The general intent behind 

a compliance path based on a pre-approved technology is to provide a level of certainty to the 

regulated entity that they would be deemed compliant with the relevant rule requirements by 

designing, installing, and operating the technology as specified in the regulation. The three preapproved compliance alternatives are each based on a particular technology approach. A 

12 As part of the feasibility determination, EPA found that the IM standards are also economically achievable. 

Essay 16 111 
compliance alternative based on a pre-approved technology entails criteria, design standards, and 

operational measures in the regulatory language specific to the pre-approved technology. The 

compliance paths based on pre-approved technologies in today’s final rule include simplified 

permit application requirements (such as reduced or minimal study requirements), reduced 

documentation, or reduced monitoring, and therefore pose greatly simplified implementation. In 

today’s final rule, there are no biological compliance monitoring requirements for any of the 

three compliance paths based on “pre-approved” technologies. 

Under the three streamlined compliance alternatives, a facility must demonstrate to the permit 

Director that traveling screens, actual intake velocity, or some combination of technology 

controls or operational measures represent BTA performance under the conditions at the site. 

The three “streamlined” compliance alternatives are (the numbering reflects the numbering in § 

125.94(c)): (3) a cooling water intake structure that EPA or the State NPDES permitting 

authority determines has an actual maximum through-screen intake velocity of 0.5 feet per 

second; (5) operating modified traveling screens whose demonstrated performance represents the 

best technology available for impingement reduction at the site (and were the basis for the 

numeric IM performance standard); or (6) operating a system or combination of technologies or 

operational measures whose demonstrated performance is the best technology available for 

impingement reduction at the site. Compliance with (3) is similar in concept to alternative (2) but 

relies instead on operational measures to ensure that the facility’s intake velocity does not exceed 

0.5 feet per second; it is because of this degree of uncertainty (i.e., that there is not a technology 

or design feature limiting the velocity) that led EPA to designate (3) as streamlined as opposed to 

pre-approved. In order to demonstrate BTA performance under compliance alternatives (5) and 

(6), a facility will need to conduct a two-year site-specific study at the same time it conducts its 

source water characterization and Entrainment Characterization Study. This study must 

demonstrate that its modified traveling screens, or combination of technology controls and 

operational measures, have been adjusted and optimized so as to minimize impingement 

mortality. If the Director concludes that the facility has demonstrated optimized performance for 

its controls the facility will have no subsequent biological monitoring and reporting requirements 

in the current permit cycle. These “streamlined” compliance alternatives are based on a 

technology or suite of technologies and practices with more variable performance, and as such 

necessitate some degree of study, in order to optimize technology performance for the sitespecific conditions encountered by a facility. A streamlined compliance alternative may require 

some level of monitoring, but once the optimal performance of the technology has been 

identified, conditions included in the permit specifying optimal operation ensure that the 

streamlined alternative is similar to or better than the impingement mortality performance 

standard. 

The compliance alternatives for “pre-approved” technologies and the streamlined compliance 

alternatives address industries concerns about the expense and burden of perpetual biological 

compliance monitoring associated with the impingement mortality performance standard when 

many technologies can be readily shown to consistently achieve EPA’s desired performance. 

IM Performance	 	 Standard

Refer to Essay 16A for the primary discussion of comments related to the calculation of the IM 

performance standard. With respect to comments on the performance standard or concerns that 

Essay 16 112 
some facilities would be unable to meet the performance standard, EPA disagrees that the 

numeric performance standard is inappropriate or that the values were inaccurately calculated 

(see Essay 16A for more discussion on how the performance standard was derived). EPA also 

disagrees that biological monitoring to demonstrate compliance with the numeric IM 

performance standard should be eliminated. Biological monitoring provided the data upon which 

the standard is based and, thus, including a compliance alternative based on it is appropriate. 

EPA also notes that inclusion of that compliance alternative is one way the final rule is structured 

to allow for future technology innovation. 

But EPA is not requiring compliance with the BTA impingement mortality standards only 

through biological monitoring data that demonstrates achievement of the numeric reduction in 

mortality levels that EPA has determined well-operated modified traveling screen will achieve. 

Rather, as described above, the final rule allows facilities to comply by employing any of seven 

alternatives, including monitored compliance with a numeric impingement mortality 

performance standard. 

Based on its review of available data and information submitted by commenters, EPA identified 

a number of other technologies and operational measures that could achieve equivalent, or better, 

performance to the impingement mortality reductions achieved with modified traveling screens 

that may be available for some sites. Thus, the final rule provides seven alternatives for 

complying with the BTA impingement mortality standards. EPA included the seven compliance 

alternatives in the final rule to provide facilities with ample flexibility to select the compliance 

alternative most consistent with their facility. In addition to biological monitoring for compliance 

with the numeric IM performance standard, the rule includes three compliance paths based on 

“pre-approved” technologies, and three compliance paths that offer a “streamlined” approach to 

compliance. EPA expects the majority of facilities will use one of these six options to comply 

with the BTA impingement mortality standards. 

Pre‐Approved Technologies

Many commenters requested that EPA “pre-approve” technologies that, once installed, would 

obviate the need for further regulatory conditions such as periodic monitoring. This is similar to 

the approach taken for cylindrical wedgewire screens in the remanded 2004 Phase II rule (see § 

125.99(a)). With respect to a compliance alternative for pre-approved technologies (i.e., 

technologies with reduced permit application or monitoring requirements), under the final rule, 

facilities are afforded greater flexibility in choosing a compliance alternative than in the 

proposed rule. As explained above, EPA makes a distinction between pre-approved technologies 

and streamlined compliance alternatives. Alternatives (1) , (2), and (4) at § 125.94(c) are preapproved technologies requiring no demonstration or only a minimal demonstration that the flow 

reduction and control measures are functioning as EPA envisioned. These are discussed further 

in the preamble. The streamlined alternatives discussed above require more detailed information 

be submitted to the Director before the Director may specify it as the requirement to control 

impingement mortality. 

As explained above, EPA has adopted, in significant measure, commenters’ suggestion in the 

impingement mortality standard to incorporate pre-approved technologies in its compliance 

alternatives. In these cases, EPA concludes its record demonstrates that use of these technologies 

Essay 16 113 
as defined in the rule will consistently and reliably enable a facility to meet or exceed the IM 

performance standard. Given the consistent and widely applicable performance data of these preapproved technologies, there is no need for ongoing biological monitoring or an optimization 

study. In each case, however, a facility is required to monitor intake flow or other parameters to 

ensure continued operations. EPA concluded the following technologies are appropriately 

deemed as pre-approved: 

	 Closed-cycle recirculating systems, defined at § 125.92 

	 Existing offshore velocity caps, defined at § 125.92 

	 Technologies that result in a design intake velocity less than or equal to 0.5 fps, including 

most modern cylindrical wedgewire screens 

EPA did not develop a process to designate additional pre-approved technologies because in 

EPA’s view a facility has ample flexibility to demonstrate a candidate technology’s effectiveness 

under § 125.94(c)(6) and, upon successful demonstration, may qualify for reduced permit 

application and monitoring requirements. This demonstration could also be used to illustrate the 

effectiveness of other combination of technologies in use at a facility. For example, the facility 

could combine two or more technologies or operational measures and demonstrate that the 

performance of its installed controls reduce impingement mortality consistent with the required 

BTA standard. 

As explained above, in the final rule CCRS is a pre-approved technology, accordingly an 

impoundment that meets the definition of CCRS at § 125.92(c)(2) is pre-approved. See preamble 

section VI.G. 

Some commenters suggested that EPA should include wedgewire screens as a pre-approved 

compliance alternative. In support of such an alternative, they cite EPA observations that most 

wedgewire screens are already designed to meet the 0.5 fps intake velocity requirement in EPA’s 

low velocity compliance alternative. EPA disagrees that a separate compliance alternative is 

appropriate for wedgewire screens. To the extent that a facility employs a wedgewire screen that 

is designed to meet the 0.5 fps intake velocity in the low velocity compliance alternative, the 

facility can avail itself of the low velocity compliance alternative. EPA does not have data that 

demonstrates that facilities with wedgewire screens that are designed to operate with an intake 

velocity above 0.5 fps would achieve the IM performance standard. However, such a facility 

may be able to demonstrate compliance by documenting impingement mortality reductions 

equivalent to the performance standard through the compliance path outlined in § 125.94(c)(6) or 

(7). In response to comments about the Phase II provision regarding wedgewire screens, today’s 

low velocity compliance alternative is more flexible than the Phase II provision for wedgewire 

screens because today’s final rule, in addition to low velocity, does not require the other 

conditions that were in Phase II (including cylindrical screen shape, waterbody type, sufficient 

counter currents/cross-flow, requirements for slot size, or total DIF). 

EPA also notes that it does not have sufficient data in its record to demonstrate that the more 

recent traveling screen designs (Geiger screens, WIP screens, Hydrolox screens, etc.), will 

reliably and consistently achieve the IM performance standard without the optimization study. 

Therefore EPA disagrees that these should be included as pre-approved compliance alternatives 

Essay 16 114 
and as such EPA did not designate these technologies as pre-approved. These technologies, like 

other modified traveling screens, require optimization in order perform equal or better than the 

Ristroph-type modified traveling screens. These technologies are listed in the examples of 

modified traveling screens in the rule definition at § 125.92. EPA notes that, where data for such 

screens was available and met the criteria for inclusion in calculation of today’s IM performance 

standard, EPA included it. See Essay 16A. EPA expects that many facilities employing these 

technologies would seek compliance through performance optimization of these technologies 

under § 125.94(c)(5), Modified Traveling Screens. 

With respect to comments on requiring additional technologies (e.g., the requirement at proposal 

for facilities employing closed-cycle cooling to also install modified traveling screens), EPA 

disagrees that facilities should be required to install multiple technologies to achieve the greatest 

reduction possible irrespective of other factors. As stated in the preamble and Essay 10, the 

Clean Water Act requires that facilities “minimize” impacts, not “eliminate” them. Further, the 

Clean Water Act provides EPA with the flexibility to consider factors other than the degree of 

reduction in determining what is best in terms of minimizing the impacts. As such, EPA is not 

mandated to base BTA solely on a technology or a group of technologies that achieves the 

greatest reduction. If a single technology is sufficient to minimize impacts, there is no reason to 

require additional technologies or to determine BTA should be based on multiple technologies, 

even if some marginal improvement in impingement could be achieved. Consequently, after 

reviewing the data in the record that demonstrated closed-cycle cooling systems achieve IM 

reduction that is equivalent to or greater than the IM performance standard, EPA eliminated the 

proposed requirement to install modified traveling screens at facilities that employ closed-cycle 

cooling and adjusted its compliance costs accordingly. EPA’s data also indicates that the 

substantial reduction in flow achieved by closed-cycle cooling is highly protective of aquatic 

resources. EPA also revised the regulatory language regarding exclusive use of an intake for 

closed-cycle cooling units to permit more flexibility. Similarly, because EPA’s data on intake 

velocity indicates that maintaining a low velocity will consistently and reliably provide adequate 

protection from impingement, additional technologies (such as screens) are not necessary if an 

intake is achieving the necessary velocity. 

With respect to comments on existing technologies that are already installed and operating at a 

facility, EPA notes and acknowledges that facilities that have already installed a technology may 

in fact have already achieved the IM BTA standard. (See Exhibit VIII-1 of the preamble for a 

summary of EPA’s projections on how facilities will choose to comply with the IM 

requirements.) Section 316(b) of the CWA requires that EPA must establish BTA standards for 

cooling water intake structures that minimize adverse environmental impacts. It does not require 

that all facilities raise their existing level of performance. That is, in absence of today’s rule, 

some facilities already meet BTA under their existing permit. Under EPA’s NPDES permitting 

regulations, all NPDES permits after the effective date of today’s rule must include conditions 

meeting today’s BTA standards. 40 CFR 122.44(b)(3). Thus, permits for all facilities must 

include conditions consistent with today’s BTA standard, which may or may not require that a 

particular facility take action to achieve additional reduction over their current performance. In 

an effort to reduce implementation burden and recognizing that some facilities already employ 

approaches that will achieve today’s BTA IM performance standard, EPA included several 

compliance alternatives in today’s final rule that would allow a facility to demonstrate that it has 

installed a pre-approved technology, or, in the case of those facilities complying via compliance 

Essay 16 115 
alternative (c)(6), the rule would allow facilities to demonstrate reductions in the rate of 

impingement to be used toward reducing impingement mortality and reflected in the calculations 

of IM in the performance optimization study. 

Streamlined	 	 Approach

EPA disagrees with commenters that indicated such streamlined compliance alternatives will 

allow facilities to claim compliance with little or no improvements. In fact, EPA anticipates that 

performance for facilities that have done optimization studies will likely exceed those used as the 

basis for the IM performance standard. This is so because the facilities used as basis for the IM 

performance standard may not have optimized their system whereas facilities electing the 

streamlined compliance alternatives must conduct a study specifically for the purpose of 

optimization. While the streamlined alternatives are intended to significantly reduce the longterm monitoring requirements for a facility (versus complying via the numeric standards), EPA 

disagrees that facilities choosing a streamlined alternative would be exempt from all data 

collection requirements pertaining to technology performance. As explained above, in the final 

rule, the streamlined alternatives require a 2-year optimization study as part of the permit 

application, in which biological data is collected and used to optimize technology performance in 

order to minimize impingement mortality. Once the site-specific operational and management 

parameters for optimized performance have been identified, the Director would establish 

enforceable permit conditions in the permit to ensure continued optimized operation of the 

technology (e.g., continuous screen rotation, use of low pressure spray wash). Enforceable 

permit conditions will help ensure that facilities achieve and maintain high levels of 

performance. Under this approach, the technology would not be operated merely to meet the IM 

performance standard, rather the approach results in a level of performance higher than the 

minimum standard. 

EPA also disagrees that perpetual monitoring is necessary to ensure long-term performance of 

IM technologies. As explained above, once a facility has demonstrated that the particular 

technology chosen for a given site can achieve the necessary impingement mortality reductions, 

no additional compliance monitoring would be required for the duration of that permit, provided 

that the conditions at the facility remain the same. EPA determined this is appropriate given the 

consistent, well-known performance of modified traveling screens when operated under set 

parameters and a reasonable certainty that such performance would continue in future operations. 

The optimization study would identify the critical elements to optimize operation and serve as 

the basis for identifying permit conditions that ensure the technology is operated to achieve 

optimal performance. While the facility would then not conduct biological compliance 

monitoring in the current permit cycle, in subsequent permit cycles, the facility would conduct an 

updated 2-year performance optimization study. Under § 125.95 the rule requires the 

optimization study be redone with every permit application unless the Director has approved the 

facilities request to waive some or all of the permit application requirements. EPA notes that all 

of these data and the draft permit would be available to the public. EPA expects that, in 

subsequent permit terms, those circumstances where there are changes in source waterbody, 

changes in operation of the facility, or changes in local species, etc., may warrant a reevaluation 

of the optimization study and the associated permit conditions reflecting optimized operation. 

Under such circumstances, EPA expects the Director would reevaluate the permit conditions to 

ensure the technology continues to be operated in an optimized fashion. EPA also notes that 

Essay 16 116 
where necessary, the Director also retains the discretion to establish additional monitoring at § 

125.96(a), including additional provisions to re-evaluate changes in operating conditions or the 

source waterbody at § 125.96(c). In this case, EPA finds the overall approach to be less 

expensive and more effective than perpetual biological monitoring. This approach also addresses 

commenters’ concerns about changing operating conditions or changes to the source waterbody 

that they believe would warrant a re-evaluation of BTA for IM. 

EPA appreciates commenter’ submittals with information on the various elements of the 

modified screens that could be modified or optimized. In response to comments that facilities 

may have limited opportunities to utilize the streamlined alternative for modified traveling 

screens, EPA agrees that, at some sites, some operational parameters may have reduced 

flexibility (e.g., many traveling screens are now rotated continuously, and no longer revolve 

based on pressure drops or a fixed timer). In EPA’s view, this should actually make 

demonstrating optimized operation easier for a facility (by reducing the number of operational 

variables to be tested during the optimization study), and therefore may have led it to include an 

overstatement of costs associated with such a study. EPA also notes that the Director may 

determine additional technologies are necessary to meet BTA, including protections for T&E 

species, shellfish, or fragile species. 

In addition, as discussed above, for a facility choosing to comply with compliance alternatives at 

§ 125.94(c)(5) and (6), technology optimization studies in subsequent permit applications 

provide for flexibility for the future, such as where changes in the facility’s operations or in the 

biota in the waterbody necessitate a different set of operating parameters in order to optimize 

operation of the technology. 

For all the reasons explained above, EPA disagrees that the optimization study should be 

eliminated for these streamlined compliance alternatives. EPA also disagrees that such studies 

would be challenging to conduct. EPA notes that facilities have been conducting impingement 

monitoring for decades and the state of the science is sufficient to conduct the sampling and 

provide the Director with an accurate assessment of the expected performance of the proposed 

technology. 

Finally, EPA notes that the impingement mortality performance standard in the final rule does 

not require specific technological or operational controls nor does it require an optimization 

study. Rather, specific technological or operational controls and/or the optimization study is 

required if a facility chooses to comply with the standard through one of the streamlined 

compliance alternatives. For example, a facility that currently has traveling screens with fish 

returns will most likely elect to comply via § 125.94c(5). In that case, the rule requires that the 

screen exhibit certain categories of design features that are demonstrated and documented to 

improve the survival rates of impinged fish. The two-year duration of the optimization study 

required for the permit application allows for the facility to capture data over a wide range of 

operational conditions with the expectation that the study will enable the facility to determine 

optimal operational procedures for its specific location; nothing precludes a facility from 

collecting more than 2 years’ worth of data. Further, the two year period will allow facilities to 

test these operational procedures over time so as to demonstrate they are the most effective for 

more than just a narrow window of time. The final rule also does not require the facility to meet 

the numeric performance standard at § 125.94(c)(7) during the optimization study, alleviating 

Essay 16 117 
commenter concerns about being issued a notice of violation while still evaluating its intake 

impingement mortality control technology. 

Other

With regard to development of an impingement technology performance database for specific 

sites, EPA disagrees that this is necessary or appropriate. EPA has already collected a significant 

amount of information on the performance and feasibility of the various impingement 

technologies. This information is compiled in the TDD and included in the record supporting this 

rule. The commenter requests that the database use a robust statistical approach for calculating 

performance of each technology. As discussed above, EPA based the IM performance standard 

on modified traveling screens and calculated the associated performance standard using a robust 

statistical approach (see Essay 16A). The performance standard serves as the basis of comparison 

for other technologies, including new and innovative technologies and approaches. EPA assumes 

that this makes unnecessary development of such a national database. 

With respect to comments requesting a provision for very low impingement rates, the final rule 

includes a de minimis provision. See § 125.94(c)(11). In seeking to avail themselves of the de 

minimis provision, facilities are required to submit data to the Director indicating that they 

experience exceptionally low impingement rates; the Director will then determine what measures 

are appropriate. EPA did not establish any metrics for what qualifies as “exceptionally low” 

impingement rates, as the Agency intends for the de minimis provision to be infrequently used. 

The NODA used the example of several fish per month; see 77 FR 34324 (June 11, 2012).As 

such, EPA disagrees with Riverkeeper’s contention that impacts will be masked under a de 

minimis provision; the absolute number of fish impinged is likely to be sufficiently low that no 

masking of significant biological impacts will be numerically possible. Said differently, a facility 

with sufficient impingement to enable the development of temporal effects likely would not 

qualify for the de minimis provision. The de minimis provision also addresses comments about 

EPA’s calculation of a limit when the numbers of organisms are statistically indeterminate. EPA 

concluded that a definition of de minimis was inappropriate, as the definition can vary on a sitespecific basis given the species impinged, the presence of threatened or endangered species near 

the intake structure, the relative abundance of fish, and other factors. EPA notes that several 

comments provided data in support of the de minimis provision, but did not provide sufficient 

data to allow EPA to define de minimis. Due to the lack of comparable data, EPA did not 

determine whether these data sets were appropriate examples of de minimis. Because EPA’s 

economic analysis did not include the cost savings of facilities determined to pose de minimis 

impacts, the cost of the rule is likely overestimated for such facilities that are able to comply via 

the de minimis provision. 

With respect to comments requesting “credit” towards compliance, the final rule also includes a 

provision to allow a facility to demonstrate credit towards meeting impingement mortality 

requirements; see § 125.94(c)(6). Under this provision, a facility can demonstrate partial (or 

complete) progress towards meeting comparable performance to the impingement mortality 

performance standard. For the system of technologies compliance alternative under § 

125.94(c)(6), the final rule, at § 122.21 (r)(6)(ii), specifies how a facility would obtain credit for 

actual flow reduction, reduced rates of impingement, reduced impingement mortality, and the 

overall performance of the system of technologies. Similarly, the compliance option described at 

Essay 16 118 
§ 125.94(c)(6) could provide credit for technologies such as barrier nets and behavioral 

technologies. EPA included a separate provision for existing offshore velocity caps at § 

125.94(c)(4). 

With respect to comments regarding the calculation baseline used in the 2004 Phase II rule, EPA 

notes that facilities could demonstrate other locational credits by documenting the difference in 

impingement rates or organism abundance at the existing intake location and, for example, a 

comparable location along the shoreline at the facility. While EPA is not retaining this provision 

from the Phase II rule for reasons articulated at 76 FR 22185, EPA acknowledges that some 

facilities and their permit authorities have already developed documentation for such an 

approach. To the extent a handful of Phase II facilities have already developed information 

supporting their calculation baseline, EPA envisions § 125.94(c)(6) will allow use of this 

information to demonstrate or show progress towards demonstrating equivalent performance for 

the compliance alternative. With respect to comments regarding EPA’s methodology for 

calculating credits (including the sample equations provided in the Federal Register notices), 

EPA disagrees that the arithmetic average is inappropriate for calculating credit towards meeting 

impingement mortality or entrainment requirements; EPA has already evaluated other 

mathematical approaches and has rejected them (see TDD Chapter 11 and Essay 16A). EPA also 

disagrees that the equations in the final preamble will lead to an incorrect implementation of the 

rule. These equations were provided as an example of how the Director may calculate credit 

towards meeting impingement mortality requirements and they represent one way in which credit 

may be calculated for a facility. With respect to long-term monitoring, as above, EPA disagrees 

that perpetual monitoring is necessary to ensure long-term performance; for example, many of 

the opportunities for credit are easily verified through flow reduction calculations or through 

documented performance of the technology. 

As to the commenter requesting a provision for an FDF variance, EPA disagrees that such a 

provision is either necessary or appropriate. Primarily, EPA notes that there are no FDF 

variances authorized for 316(b). However, even if such variances were authorized, today’s final 

rule offers a wide variety of compliance alternatives for impingement mortality controls, as well 

as a site-specific determination for entrainment; as a result, there is no need to develop a variance 

provision. 

In support of a comment disagreeing with EPA’s assertion that fine mesh larger than 2 mm does 

not provide significant exclusion of eggs from an intake (and thus provides reliable entrainment 

reduction), a commenter provided citations with egg sizes that exceed 2 millimeters. First, EPA 

notes a 2-mm diameter round egg can be squeezed through a -2-mm square mesh. While EPA 

appreciates the comment and data, the fact remains that the vast majority of eggs and early life 

stages of larvae are smaller than 2 mm, as documented by the numerous biological studies in the 

record. See, for example, Bagenal (1971, DCN 12-6975) showing 4 of the 46 marine species 

evaluated have fish eggs that could potentially be larger than 2 mm. For freshwater species see, 

for example, Bonisławska et al (2001, DCN 12-6976) showing both eggs and yolk spheres of 

species (other than trout and pike) have a mean diameter size smaller than 2 mm. Further, fish 

eggs are not solid spheres, as such they can be compressed or forced through openings slightly 

smaller than their natural diameter. Second, the commenter did not provide any details on 

whether the studies were conducted in the context of entrainment at an intake structure. For 

example, slot velocity has been identified as a major factor in the ability of fine mesh screens to 

Essay 16 119 
exclude both eggs and larvae. EPA agrees that some larger eggs may be retained by larger slot 

sizes, noting that such situations are essentially impinging the eggs. The overwhelming body of 

studies in EPA’s record clearly shows that most eggs are not retained on 2 mm or larger mesh 

sizes (and therefore would become entrained in absence of other controls), and that in most 

instances 0.5-mm mesh sizes are necessary to collect the majority of entrainable organisms to 

prevent them from being entrained. See for example “Field Evaluation of Wedgewire Screens for 

Protecting Early Life Stages at Cooling Water Intake Structures: Chesapeake Bay Studies” 

(EPRI, DCN 10-5558). Further, EPA notes the organisms cited by commenters are too small 

(i.e., smaller than the 3/8-inch mesh size that defines an impingeable organism, see § 125.92) to 

affect the calculation of the performance standards for impingement mortality. See preamble 

Section VI for more information about why fine mesh is not BTA for entrainment. 

With respect to the comment that some facilities are faced with historically low water levels and 

may require booster or emergency pumps which do not have screens, EPA is aware that some 

facilities face critical shortages of cooling water, such as lowered source water levels that may 

require the installation of booster/emergency pumps or other equipment. EPA notes that it visited 

several facilities that retrofitted to closed-cycle cooling as a remedy to this problem or a similar 

one (see, e.g., DCN 10-6524 and 10-6534). By converting to closed-cycle cooling, these 

facilities’ cooling water needs were greatly reduced and the ability of the source water to provide 

sufficient flow was restored. Facility actions in response to decreased water availability and 

similar circumstances are beyond the scope of this rule, nevertheless EPA supports actions that 

reduce the withdrawal of water for cooling, such as reuse of process water or gray water. The 

final rule has incorporated additional compliance alternatives that provide greater flexibility for 

facilities to meet the rule requirements while reducing source water withdrawals such as reuse of 

recycled water and gray water (see § 125.94(c)(10)). 

For information on how the final rule addresses subcategorization, including a framework based 

on waterbody type, refer to TDD Chapter 4 and Essay 19. For information about makeup 

withdrawals and how the final rule addresses fire suppression and other emergency withdrawals, 

refer to Essay 14. For information on how the final rule addresses cost-benefit or cost-cost tests, 

refer to Essay 15. For information on how the final rule addresses the entrapment and barrier net 

provisions in the proposed rule and closed-cycle cooling, refer to Essay 18. For information on 

how the final rule addresses credits for unit closures or retirements, refer to Essay 18. For 

information on prior installations of technologies, prior determinations of BTA, and the use of 

existing documents, refer to Essay 22; EPA notes that many studies or technologies that have 

previously been conducted or installed will likely be acceptable under the final rule. 

Entrainment Requirements

Riverkeeper argued against a site-specific approach to entrainment, stating that the proposed rule 

provided the Director with unlimited discretion in what factors to consider in determining BTA. 

Additionally, they argued that unlimited discretion is not equivalent to setting a standard. They 

added that states are ill-equipped to oversee the study process and to review the results. 

Industry commenters overwhelmingly supported using a site-specific approach to address 

entrainment. Some commenters noted that the proposed rule did not specify how the Director 

would establish entrainment requirements and what factors would be considered (including those 

Essay 16 120 
listed in the regulatory language). Other commenters added that a site-specific approach will lead 

to highly variable results, given how open-ended the Director’s criteria are. Some commenters 

stated that a wide variety of considerations could affect decision-making on entrainment 

controls, including nuclear-fueled facilities, previous efforts to address impingement and 

entrainment, lack of water depth, conflicts with navigation, and equipment changes that would 

trigger requirements under other regulatory programs. Other commenters stated that EPA should 

provide guidance and research on entrainment controls to the Director. Another commenter 

stated that EPA should not use the phrase “maximum reduction in entrainment warranted” to 

describe the development of entrainment BTA, as it may lead to inappropriate BTA 

determinations. 

Commenters also advocated certain subcategories for entrainment requirements, such as no 

entrainment requirements for facilities located on lakes, for facilities withdrawing less than 5 

percent of a river’s mean annual flow, or those facilities with a capacity utilization rate less than 

15 percent. Each of these metrics was included in the Phase II rule. Some commenters advocated 

implementing entrainment controls in such a way that threatened and endangered species would 

not be adversely affected. 

As discussed in the preamble and Essay 15, EPA determined that there are no technologies 

available, demonstrated, and feasible for which to establish national entrainment requirements, 

and instead has established a process in the rule to make site-specific entrainment BTA 

determinations. EPA disagrees with comments stating that the Director has been given 

“unfettered discretion” and also disagrees that it has not set a standard. The Director has been 

afforded significant flexibility in setting entrainment requirements, but the final rule requires 

determination of site-specific entrainment control measures through a structured process that all 

facilities and Directors must follow. Also see Essay 10. EPA also disagrees with comments that 

the states are unprepared to undertake a site-specific determination for entrainment; as noted in 

the preamble and Essay 15, Directors have been using a site-specific approach for decades. 

Today’s final rule establishes a framework for submitting materials with the facility’s NPDES 

permit application, a process with which Directors are highly experienced. Today’s framework 

creates a more standardized set of expectations for both permittees and permit writers. A 

significant amount of information will be collected and submitted for the Director’s (and 

public’s) review. In many cases, this will include studies assessing closed-cycle cooling (as part 

of § 122.21(r)(10)) as one possible solution to address entrainment. 

EPA also notes that, aside from advocating for closed-cycle cooling as the sole technology basis 

for the BTA entrainment standard (which EPA has concluded is not BTA for the reasons 

specified in the option selection section of the preamble), Riverkeeper has not provided another 

viable, effective alternative that is widely available for addressing entrainment in a national 

rulemaking. In the final rule, EPA has included direct guidance on factors that must be 

considered by the Director. EPA will evaluate the need for further implementation guidance after 

promulgation of the rule. EPA notes that it has already provided a large quantity of information 

on entrainment controls in the TDD and record. EPA disagrees that the language used in § 

125.94(d) is inappropriate, as it conveys a need to be protective while considering a number of 

other factors. 

Essay 16 121 
As described in the preamble, TDD, and Essay 19, EPA also examined a number of possible 

subcategorization strategies, including waterbody type, and determined no subcategorization 

schemes were supported by the data or EPA’s analyses. 

As discussed in the preamble and above, EPA has established site-specific requirements for 

entrainment; as a result, the Director may consider a variety of factors in developing those 

requirements, including those suggested by the commenters. For information on how EPA 

considered impacts to threatened and endangered species, refer to Essays 10, 69, and 72. Also 

refer to Essay 15 for a discussion on the role of costs and benefits in determining BTA in the 

final rule. 

Technologies to Address Impingement and Entrainment

For a more detailed discussion of the technologies and operational measures available to reduce 

impingement mortality and entrainment and a summary description of their effectiveness, refer 

to preamble section VI, Essay 18 and the TDD. This essay subsection is more narrowly focused 

on the process used to select technologies as the basis for BTA for the final rule. 

Commenters generally agreed that modified traveling screens are a reasonable choice as the 

technology basis for establishment of the impingement mortality standard, as they are in wide 

use and have well-established performance. These commenters argue, however, that modified 

traveling screens are not feasible at all facilities and that EPA should consider including 

additional technologies as candidates for BTA. Commenters also stated that some modified 

screens may not require all of the features listed in the proposed rule to be effective. Other 

commenters argued that EPA should limit the level of modification that a Director may require 

as upgrades to a modified traveling screen. Some commenters also stated that modified traveling 

screens can still damage fish. Other commenters stated that fish returns should not be required. 

Riverkeeper supported the requirements to maintain a maximum of 15 percent screen blockage 

and to eliminate carryover. Industry commenters opposed the requirements, stating that these 

requirements were difficult to implement and measure. Those commenters added that the 

requirements are unnecessary, as facilities have an incentive to keep their screens clear to 

promote proper operation of the cooling system and prevent debris carryover and damage to the 

cooling system. 

Some commenters stated that EPA should not reject fine mesh screens as a technology, as the 

technology is evolving and may be the only technology available to reduce entrainment at some 

facilities. 

Some commenters stated that the final rule should require the installation of a screen of some 

variety. 

Other commenters state that EPA should include an analysis of cost and other impacts that may 

result from facilities that have installed (or begun installing) a given technology that ultimately 

conflicts with or otherwise does not satisfy the final rule. 

EPA concludes that modified traveling screens with fish return are the proper technology basis 

for establishment of the best technology available impingement mortality standard for the 

Essay 16 122 
reasons previously explained. With respect to the availability of modified traveling screens, EPA 

disagrees that the technology is not available. See section VI.D of the preamble and Chapter 6 of 

the TDD. However, as previously discussed, traveling screens may not be the most cost effective 

technology for all facilities. Consequently, also as discussed previously, the final rule includes 

seven compliance alternatives for the IM performance standards. Additionally, for the final rule, 

EPA changed its definition of modified traveling screens from that of the proposed rule to 

include other screens that have the same critical protective features, such as WIP screens, Geiger 

screens, and Hydrolox screens. This is consistent with the data used to determine the 

impingement mortality performance standard, which includes data from studies for a Geiger 

screen and the WIP screen. Refer to the TDD and Essay 16A for more information. With respect 

to the fish protection features on modified traveling screens, EPA agrees that a modified 

traveling screen can be effective even if it does not employ all of the features described in the 

final rule; however, in order to utilize the streamlined option for screens (§ 125.94(c)(5)), the 

rule requires that the screens meet certain technical specifications. The rule does not require that 

facilities comply with the IM standard via the streamlined compliance alternative for screens so 

facilities that wish to use other technologies or screens that do not meet the required technical 

specifications have the option of doing so as long as they can comply with one of the other six 

IM standard compliance alternatives. With respect to damage to fish by modified traveling 

screens, EPA recognizes that these screens will not achieve 100 percent reduction in 

impingement mortality, but notes that the Clean Water Act simply requires that adverse impacts 

be “minimized” and not “eliminated.” EPA notes that no technology completely eliminates IM 

and that other technologies evaluated that likely exceed the performance of traveling screens are 

not widely available and are thus, not BTA. EPA’s analysis confirms that modified traveling 

screens can be highly effective when properly designed and operated. For information on fish 

returns, refer to Essay 18. 

With respect to the screen blockage and carryover requirements, EPA determined that these 

requirements are not necessary because facilities already have an incentive to maintain clean 

screens (to ensure continued operation of the facility). In addition, these requirements could be 

extremely difficult for a facility to measure. Therefore EPA has eliminated them from the final 

rule. EPA notes, however, that the principles behind those requirements (e.g., maintaining a 

clean screen) remain important and should be considered by the Director in determining whether 

an intake technology is being properly operated and maintained. In addition, the Director could 

determine that circumstances dictated inclusion of such requirements as appropriate conditions 

of a facility’s permit. EPA expects such factors will be identified in the technology optimization 

study and may be incorporated as permit conditions where appropriate. 

With respect to the comment that EPA should not determine fine mesh screens are not BTA as 

the technology is evolving, EPA agrees that fine mesh screens can be effective in reducing 

entrainment for certain species and in some locations. For this reason, fine mesh screens are one 

technology that can be considered by the Director as BTA for a given site. However, as 

described in the preamble, TDD, and other essays, EPA does not consider fine mesh screens to 

be a nationally available technology to address entrainment. EPA considered the costs and 

availability of fine mesh screens, and found that the conversion of course mesh to fine mesh 

would cause an increase in the number and size of screen banks to accommodate the reduced 

through screen area. While a doubling of required screens is not unusual, in a substantial number 

of instances the required increase in screen banks could exceed a 5-fold increase, which is a level 

Essay 16 123 
of expansion of the existing CWIS that many facilities would not be able to accomplish with 

existing available waterfront acres. EPA also rejected fine mesh because of the low survival of 

most larvae and many eggs; see TDD and preamble for further discussion. Under the final rule, 

facilities will provide the Director with information for each facility including costs and 

performance of fine mesh screens, thus enabling the Director to fully consider fine mesh screens 

as a potential site-specific BTA technology. The site-specific BTA entrainment framework in 

today’s rule, by its very nature, would enable evolution in fine mesh screens to be considered, as 

appropriate, in determining the site-specific BTA requirements. 

EPA disagrees with comments claiming that screens should be required in all cases, as other 

technologies may perform equal or better than screens, when available for a specific site. EPA 

further disagrees that the final rule should require some type of screen, as some intake 

configurations do not need a screen to be effective. For example, a velocity cap may not have a 

screen, but due to its operation and location, it can be deemed BTA. Similarly, closed-cycle is a 

high performing technology that performs better than screens. Thus a facility with properly 

operated cooling towers should not have to install modified traveling screens in addition. EPA 

notes that most intakes do have screens of some type to prevent the entry of debris into the 

cooling system, but does not see a need to require screens at all facilities. 

With respect to consideration of costs incurred for technologies already installed, EPA conducted 

a cost and impacts analysis for this rule, and found that the BTA requirements of the rule are 

economically achievable. EPA disagrees that EPA’s analysis must include other expenses 

already undertaken by the facility, noting that the rule analysis of cost reflects the incremental 

costs of a facility. To the extent a facility has debt, this is reflected in the EA and this analysis 

may be considered to include technologies and operating practices already in place. EPA found 

that the rule is economically achievable; see preamble section VII. The flexibilities in the rule 

provide alternatives that may be less costly for some facilities. To the extent a facility is 

developing a new technology, the “systems of technologies” and the IM performance standard 

compliance alternatives are both available. 

Essay 16 124 
                                                            

Essay 16A: Impingement Mortality Performance Standards

EPA received numerous comments concerning the proposed monthly and annual average 

impingement mortality performance standards. Comments assert that the proposed standards 

would be too stringent and facilities using the model technology would not achieve them on a 

consistent basis. The comments also claim that EPA based the proposed standards upon data that 

did not fully capture site-specific factors contributing to variability in both impingement rates 

and resulting impingement mortality. Comments also expressed concern regarding the 

methodology used to derive the performance standards. 

Introduction

This essay describes the comments on the proposed impingement mortality (IM) performance 

standards and EPA’s subsequent reevaluation of criteria for the data acceptance and the 

methodology ultimately used for the determination of the IM performance. The proposal 

included both a monthly average and an annual average numeric IM performance standard; both 

were based upon data from three facilities selected using a well-defined set of criteria. 

Comments generally suggest that EPA either delete any numerical standards altogether, 

reevaluate the criteria for data acceptance, establish less stringent requirements, and provide for 

pre-approved compliance approaches. 

Because EPA has developed different compliance strategies than typically used for annual 

average limitations promulgated under the Clean Water Act, EPA changed the name of its 

proposed annual average impingement mortality limitation to “IM performance standard” for the 

final rule.13 EPA is doing this to help make it clear that CWA section 316(b) requirements are 

not effluent limitations guidelines and standards (ELGs). In the record, EPA may also refer to the 

final IM performance standard as the 12-month percent survival performance standards, the 

percent survival standard, or percent SPS. See Legal Authority in the preamble for a discussion 

of the invitation to look at the CWA factors for ELG in establishing CWA section 316(b) 

requirements. 

EPA notes that the final rule deletes the requirement for a monthly standard, as discussed below. 

Further, compliance strategies including calculations for demonstrating compliance when 

meeting a 12-month IM performance standard are different than those used for annual average 

limitations, therefore the final rule specifically refers to 12-month performance standard to avoid 

possible confusion. Specifically, the final rule includes a 12-month IM performance standard, 

which is not the same as an annual limitation. To further avoid confusion over the meaning of 

“annual” or “annual average” the rule precisely refers to the requirement as a “12-month” 

impingement mortality performance standard. This is a more transparent description of what the 

performance standard requires, as well as what the performance standard is based on. 

Upon reevaluation of the available studies and the analysis, EPA revised the data exclusion 

criteria, thereby increasing the size (number of studies) and variability of the database. The final 

13 Throughout this document, EPA refers to the proposed limitations as standards. EPA is taking this approach in 

this essay so that the reader can easily compare the proposed “standard” to the final standard. 

Essay 16A 125 
database consists of data from 17 facilities located in a large geographic area stretching from 

Massachusetts to Florida and as far west as Minnesota and Nebraska. This increased dataset 

addresses both variability in the rate of impingement and the subsequent rate of impingement 

mortality. For the 12-month IM performance standard in the final rule, EPA used the same 

statistical methodology as it had proposed, because it is still an appropriate method for the 

available data. EPA did not receive any information or data to the contrary. By applying this 

methodology to the revised database, EPA calculated that the 12-month IM performance 

standard was 24 percent. This means that no more than 24 percent of the impinged fish and 

shellfish may die or alternatively at least 76 percent of the impinged fish and shellfish must live. 

While the resulting IM performance standard is approximately double that of the proposed rule 

standard, the final rule dataset addresses concerns about (1) the stringency of the proposed 

annual standard, (2) a standard based on three best-performing facilities, and (3) facilities used in 

calculating the standard are all located in a single geographic region. See more detailed 

discussion below. In addition, by adopting the 12-month IM performance standard, EPA 

increased the regulation’s flexibility to address industry concerns about compliance with annual 

averages. With respect to comments about rate of impingement and the specific comment about a 

facility obtaining credit for measures that reduce the rate of impingement in the first place, a 

facility may choose to demonstrate the rate of impingement as part of the “systems of 

technologies” compliance alternative; see preamble and the rule at § 125.94(c) for more 

discussion. This essay consists of six main sections that address detailed comments about EPA’s 

justification for the proposed standards, alternative forms of the standards, data selection, 

statistical methodology, achievability and compliance issues, and additional public review. 

Justification for the Proposed Standards

Comments express concerns about EPA’s justification for the proposed annual average and 

monthly average standards. This section summarizes the comments about both types of standards 

and provides EPA’s response. In particular, this section addresses why a 12-month performance 

standard is appropriate, and why the monthly standard is unnecessary. 

The proposal cited the regulation for the pulp and paper category (40 CFR 430) as an example of 

a Clean Water Act (CWA) rule with an annual average limitation. Comments assert that EPA’s 

adoption of the annual average concept was based upon an inappropriate and faulty comparison. 

They assert that natural resource management required by 316(b) differs from the pollution 

control required by effluent guidelines. They assert that controlling pollution in wastewater 

discharges is not the same as controlling biological organisms that come in contact with cooling 

water intake structures. Within any industrial effluent guidelines category or subcategory, waste 

streams are likely to be similar between facilities and treatable with the same or similar 

technologies, regardless of where the facilities are. Because of what commenters consider an 

imperfect analogy between control of industrial waste streams and intake structures, comments 

conclude that EPA cannot justify an annual average limitation for 316(b) based upon the 

construct established in the pulp and paper annual effluent limitations or other annual CWA 

limitations. Instead, for facilities subject to 316(b) requirements, comments assert that the 

biological conditions are widely variable at intake structures throughout the country, thus 

requiring different technologies for successful IM control. 

Essay 16A 126 
EPA disagrees that facilities cannot effectively apply BTA technology or its equivalent in a 

consistent manner within the biological conditions specified in the final regulation. EPA’s record 

shows dozens of studies specific to traveling water screens, indicating the status of the 

technology as a widely available, demonstrated, and feasible technology. Further studies show 

similar levels of performance with screens other than traveling screens, but with the same types 

of fish protection features. Thus EPA’s record shows a minimum level of performance can in 

fact be obtained with certain technology. More specifically, EPA’s record shows 17 studies 

evaluating technologies with the fish protection features found in modified traveling screens with 

fish returns, and these studies show the technology does in fact provide a consistent level of IM 

control. This consistent level of performance is further enhanced because the definition of 

impingement in the rule excludes organisms smaller than a 3/8-inch mesh size; at this mesh size, 

impingement does not include the most fragile life stages (eggs and larvae). EPA’s analysis 

shows when fragile species are excluded from the 12-month performance standard calculation, 

there is very little variation in performance exist across geographic locations. As discussed in the 

preamble, EPA is: keeping the definition of impingement in the final rule, deleting the species of 

concern provision, and is adding a definition of fragile species to the rule. These three 

components clearly articulate applicability of the performance standards. A thorough review of 

these studies demonstrates for non-fragile species, the performance for properly operated 

technology is in fact highly predictable. See TDD Chapter 11. 

EPA recognizes that facilities may prefer to apply different treatment strategies at different 

intake locations, particularly where intake location or other management measures have resulted 

in reduced rates of impingement. EPA agrees that a facility that has considerably reduced the rate 

of impingement should be able to get credit for such reductions. For this reason, the final rule 

allows a systems of technology approach by where a facility can demonstrate reduced rates of 

impingement as part achieving a level of performance comparable to the 12-month IM 

performance standard. See the Basis for the Final Regulation section of the preamble for further 

information. 

While EPA could have included a monthly performance standard and commensurate biological 

compliance monitoring, EPA found that achieving the 12-month performance standard would 

achieve the same overall environmental improvement as a monthly performance standard. As 

discussed further below, the performance of the BTA technology is consistently achievable over 

the course of a year, and the performance is consistent across the wide range of intake structures, 

waterbody types, and geographical locations. Further, the 12-month performance standard will 

require a facility to actively evaluate performance during the 12-month period enabling the 

facility to optimize the technology to improve performance to counter balance a result above the 

standard by one below the standard. If EPA had included a monthly standard, it would have 

similarly needed to incorporate allowances for exceedances. Allowing for exceedances would 

have provided no incentive for improving operations for such exceedances. Therefore, EPA 

concludes the additional burden and expense of a monthly performance standard would not 

increase the environmental benefit over that already achieved by facilities employing various 

technologies to meet the 12-month performance standard. Thus the 12-month performance 

standard on its own is appropriate, and there is no need for monthly performance standards. EPA 

notes that, contrary to commenters’ assertions, EPA is not relying on the use of annual average 

limitation in other regulations as the justification for its use here. EPA’s cite to a past example of 

Essay 16A 127 
where EPA used an annual average limitation approach within its CWA program demonstrates 

that this approach has been validly used in other cases. 

For the proposed monthly average standard, comments assert that its purpose and benefits are 

unclear, and thus, EPA should delete it from the final regulation. Comments claim that a monthly 

standard has numerous drawbacks due to factors including the seasonal nature of impingement, 

water temperature, salinity, fish abundance, and community composition. Other comments assert 

that monthly data would rely on frequent occurrence of low impingement catches which result in 

small sample sizes and render monthly estimates imprecise. Other comments are concerned 

about the high risk of false violations associated with monthly standards and incompatibility of 

monthly IM standards with credits for alternative technologies. Other comments assert that EPA 

should only use an annual standard, and not a monthly average, to avoid penalizing facilities 

during any months when seasonal measures are not in place. Some commenters favor the 

monthly standard, and support frequent biological monitoring to demonstrate the monthly 

standard is being met. 

EPA disagrees with the implication that facilities cannot control BTA performance on a regular 

and ongoing basis. However, EPA agrees that a monthly IM performance standard is not 

necessary in order to achieve the desired long term IM performance for the reasons explained 

above. Therefore, the final rule does not include a monthly average. 

The final rule also uses the IM performance standard as a measure of performance for 

determining which technologies should be deemed pre-approved, which technologies should be 

eligible for streamlined compliance such as reduced monitoring, and provides the permit 

authority a clear and transparent metric for comparison purposes when determining whether 

technologies other than modified traveling screens are appropriately deemed BTA for a given 

location. 

Alternative Forms of the Standards

The EPA expressed the proposed monthly average and annual average standards as maximum 

percentages of impingement mortality that facilities were not to exceed, on average, in each 

month or 12-month period identified by the permit authority. Comments suggest several 

alternatives to the percentage basis for the IM standards. The suggested alternatives include 

reduced impingement measures, biomass, impingement mortality loss, percent survival, speciesspecific mortality rates, or arbitrary values. 

Riverkeeper’s comments assert that EPA should not establish the proposed standards for IM 

because it allows the technology to impinge an unlimited number of fish and requires that the 

facility determine how many of each species survive. Riverkeeper recommends a standard based 

on reduced impingement rather than impingement mortality (such as an intake velocity 

standard), because it would be more practical, certain, and effective by preventing impingement 

and thereby avoiding sub-lethal harm. The EPA agrees that it is desirable to prevent both 

impingement and impingement mortality. As explained in the preamble, EPA considered other 

technology bases such as reduced intake velocity (i.e., 0.5 ft/sec), far offshore locations, and 

closed-cycle cooling that are capable of reducing both I and IM. The EPA found that reduced 

intake velocity and closed-cycle cooling are both more effective at reducing I and IM than the 

annual standard based on the performance of well-operated modified traveling screens. Because 

Essay 16A 128 
the performance of these two technologies exceeds the performance of well-operated modified 

traveling screens, the final rule includes compliance alternatives based on these two 

technologies. However, the EPA finds that reduced intake velocity and closed-cycle cooling are 

not available for many facilities, and neither of these technologies are therefore the basis for 

BTA. Far offshore location alone did not consistently reduce impingement to the level of welloperated traveling screens. See Section VI of the preamble and Essay 17 for further discussion. 

Because they consider a requirement for purely meeting a percent survival rate (IM standard) to 

be a poor measure of environmental impact, other comments suggest that the EPA base the 

limitation upon biomass instead of an organism count or percentage. In support of their 

comment, they also assert that for the purposes of counting impinged mortality, a fish egg should 

not count the same as a grown fish. First, EPA received limited data from three facilities upon 

which it could base a standard on biomass, and found that standards based on biomass required a 

large amount of waterbody specific data that the EPA did not have and that commenters did not 

provide. Therefore a biomass standard could not be determined. Second, EPA disagrees that a 

standard based upon biomass would be appropriate because it would not protect species with low 

biomasses. In other words, under a biomass approach the facility could impinge and kill 

numerous small sized fish as long as the prescribed mass standard had not been exceeded. Third, 

EPA disagrees with the need for an approach to IM that counts eggs differently from grown fish. 

EPA considers an adjustment for fish eggs to be unnecessary, because the IM performance 

standard applies only to impingeable organisms. Impingement is defined in the rule at § 125.92. 

The EPA found that the majority of eggs are smaller than a 1.0-mm mesh, and industry-supplied 

data showing that only in the rarest of circumstances are eggs larger than 2.0-mm mesh. These 

data supports EPA’s final rule definition for impingement. To be consistent with these findings, 

EPA notes that the screens forming the basis for the final rule performance standards must have a 

maximum spacing of 0.57 inches (roughly 1.4 cm). 

Another comment suggests that the final rule distinguish between “impingement mortality rate” 

(the fraction of impinged fish which die from impingement) and “impingement mortality loss” 

(mortality losses expressed as a percentage of baseline conditions as described in the NODA). 

EPA agrees with the comment in principle. The proposed regulatory definitions distinguish 

between impingement and impingement mortality. In the NODA, EPA further clarified the 

distinction, and made it clear that reductions in impingement were intended to count as 

reductions in mortality. EPA provided examples in the FR notice. For example, under certain 

compliance alternatives, the final rule provides for an allowance for the reduction in fish 

potentially impinged when considering the number that are actually impinged by the CWIS. For 

example, a facility may use acoustic deterrents to prevent a species from impinging the first 

place. That facility could demonstrate the rate of impingement at the CWIS both with and 

without the acoustic deterrent. EPA considers this reduction in impingement to be an equivalent 

reduction in IM, and thus, the resulting calculated IM rate is an estimate of the efficacy of the 

overall combination of technology and operational measures at that intake. This estimated IM 

rate is the equivalent of “impingement mortality loss” as defined by the comment. In the final 

rule, EPA is maintaining the definitions of me and IM in the regulatory language; thus the EPA 

continues to clearly distinguish between the two concepts and considers any additional 

terminology to be unnecessary. 

Essay 16A 129 
EPA disagrees with comments that survival percentages instead of mortality percentages should 

be used as the basis for standards development. Because percent IM and percent survival 

together should sum to 100 percent, one can be used to calculate the other (e.g., percent 

survival=100- percent IM). Performance studies were not found to consistently report one metric 

over the other. The final rule’s IM performance standard places an upper bound on mortality, 

that is, the percentage of fish that die from impingement. In contrast, placing a lower bound on 

survival could be viewed as setting less stringent and therefore less protective standards. EPA’s 

selected final rule approach, as discussed above, requires an optimization study. This approach 

precludes facilities from doing the bare minimum to achieve the performance standard. EPA 

notes that some comments appear to confuse mortality and survival. For example, Riverkeeper 

incorrectly states that the proposed annual standard of 12 percent (final IM performance standard 

is 24 percent) would have allowed 88 percent (i.e., 100 percent -12 percent =88 percent) to die, 

when the correct value is 12 percent. Contrary to another comment’s assertion that the regulation 

does not consider stressed fish (e.g., the comment cites the Huntley study), the regulation 

requires fish to be held for a period of time after impingement to determine if any injuries were 

severe enough to cause mortality. In the final rule Latent mortality is defined at § 125.92 and 

means the delayed mortality of organisms that were initially alive upon being impinged or 

entrained but that do not survive the delayed effects of impingement and entrainment during an 

extended holding period. Delayed effects of impingement and entrainment include but are not 

limited to temperature change, physical stresses, and chemical stresses. The EPA has clearly 

identified latent mortality to ensure it can be determined whether any mortality is a result of 

impingement. See discussion about holding times in the Data Selection section below. 

The proposed rule would allow the Director to determine site-specific species of concern for 

which the performance standards would be applied. Comments suggest that EPA should further 

consider species-specific mortality rates in revising the proposed standards for the final rule. For 

example, some commenters assert that EPA should incorporate species-specific information into 

the revised standards and cite an UWAG analysis as supporting the approach. Based upon a more 

inclusive BTA data set than the EPA’s proposed database, UWAG’s Table 2 presents average 

percent IM values of 5 percent, 17 percent, and 39 percent for high, medium, and low survival 

potential species. (UWAG 2974 Attachment 2 Table 2). Comments assert that the analysis 

demonstrates the need for separate standards for fish of different survival potentials. EPA agrees 

in part. First, the technology basis for the IM performance standard in the final rule will not 

control IM for fragile fish species. EPA did not identify a nationally applicable technology that 

could serve as a BTA basis for standards specific to fragile species. For example, EPA found that 

a low intake velocity such as 0.1 ft/s could be protective of salmonids, and behavioral deterrent 

systems could be tuned for some fragile species, however neither of these technologies is widely 

available to the industry. Fragile fish species are specifically excluded from the IM performance 

standard in the final rule and the final rule includes a definition of fragile fish corresponding to 

the exact data and methodology used by EPA to calculate the performance standards. The final 

rule does not establish national requirements for facilities to control IM of fragile fish. Second, 

after evaluating differences in fish mortality rates, EPA based the final rule’s IM performance 

standard upon data for non-fragile fish, as explained in Essay 22. The EPA made this change to 

ensure the regulatory definitions and the IM performance standard are clear, reproducible, 

transparent, and correlate to EPA’s methodology for calculating the IM performance standard. 

Based on the costs of monitoring and biological evaluations provided in comments, EPA 

determined that additional regulatory requirements to document further distinction between 

Essay 16A 130 
species would be an unnecessary burden, as it would result in unnecessary complications and 

expense for facilities in monitoring and evaluating impinged fish species. Further, the 

commenter’s approach is not necessary because the final rule is readily implementable and 

applicable nationally, ensures environmental protection, and is achievable. Finally, such an 

approach could result in a different technology basis for each classification of fish survival 

(fragile vs. hearty), and the different technologies may be incompatible. Again, the resulting 

level of complexity at some locations would be unworkable. 

Other comments suggest arbitrary values for the standards. One suggests that the final rule 

specify a value of 50 percent for the annual average standard. No data was provided supporting 

the approach. Another comment suggests values of 20 percent and 39 percent to help account for 

variability, derived using EPA’s proposed standards but adjusted downwards by 10 percent. 

Commenters based this approach on EPA’s Phase I requirements that considered 90 percent of 

BTA to be comparable performance. The 10 percent margin of error was appropriate in Phase I 

because the new facility rule required EPA to predict the effect of the regulatory approach at a 

new facility based on limited empirical data. The variety of methods, sources, underlying studies 

themselves, sampling errors, and natural fluctuations also skew the results on a day to day basis. 

See Phase I TDD, Chapter 5, EPA-821-R-01-036. The Courts found in favor of EPA using the 

90 percent comparable to indicate in the regulation the amount of uncertainty that was 

considered “tolerable.” In contrast, today’s existing facility final rule includes a more 

comprehensive set of data; the data used to determine the IM performance standard already 

include variability across species, location, waterbody type, and other factors; and the final rule 

performance standard reflects 12 months performance rather than daily. Therefore, additional 

adjustments for variability are not necessary. EPA thus disagrees with the commenter’s 

recommendation of using 90 percent comparable, an approach that would lower what has been 

identified as an achievable standard by an additional 10 percent. EPA disagrees with these 

comments and has based the final rule’s IM performance standard upon facility performance 

studies with the data selected using well-defined criteria as specified in the proposed rule and 

NODA, and modeled using well-known statistical concepts, as further explained in the next two 

sections. 

Data Selection

EPA based the proposed standards upon eight data sets from three facilities, all located in the 

State of New York. Comments expressed concerns about the sample size, limited geographic 

region represented in the data sets, variability reflected in the data, data exclusions, data errors, 

and documentation. This section summarizes the comments and provides EPA’s reevaluation of 

the data for each issue raised in the comments. 

Comment Summary

The comments raise many issues related to the EPA’s selection of the data used as the basis of 

the proposed IM standards. This section provides a summary of the comments, followed by 

sections that describe EPA’s evaluation of the comments. 

Comments describe several issues related to the EPA’s data selection. Comments assert the 

proposal data were insufficient (i.e., too small a sample size) for the modeling of a statistical 

Essay 16A 131 
distribution. Comments also assert that the proposal data did not reflect variations due to 

waterbody type, geographic location, species present, environmental conditions, operating 

parameters, seasonal variability (e.g., in fish species, abundance, and impingement), and year to 

year variability. Some comments assert that the eight data points used in the analyses were not 

independent observations but were artificially created; they note that the assumption that there is 

independence and adequate replication for testing monthly variability in IM is not statistically 

nor scientifically supported. Some comments claim that the EPA made errors in selecting or 

labeling certain data sets. Other comments recommend that the EPA should change its criteria to 

include data from specific studies. Some comments note that the EPA relied on second-party 

reviews of studies, not the more complete, original study reports. Other comments argue that the 

EPA should not eliminate laboratory-based studies. Other comments claim that the requirement 

that acceptable studies contain reported values that are “actual measurements” of IM is 

needlessly restrictive, as it would preclude consideration of studies based on modeling or 

estimates. Other comments note that the EPA’s proposal documentation did not identify the 

specific criterion used to eliminate specified datasets, making it impossible to determine if the 

EPA had applied the exclusion criteria correctly. 

Comments on the EPA’s holding time restrictions claim that they establish an arbitrary range of 

holding time conditions for a test method that is highly sensitive to such conditions; however, 

there is considerable disagreement in recommendations and concerns. Some comments 

recommend that the IM standard database should exclude data for holding times greater than 48 

hours because the data may reflect mortality associated with holding rather than from the 

impingement and collection process. Other comments argue that the standard database should 

include data with holding times greater than 48 hours because there are several studies (e.g., 

Beak 1987; Tetra Tech memo DCN 10-6709) in which longer holding periods did not result in 

high mortality. Comments also note that data for holding times less than 24 hours and interim 

evaluations during a longer holding time can provide useful information. Still others assert that 

EPA has no technical or scientific basis for assuming that the standards based upon data 

calculated using a 24-hour holding period are achievable at a 48-hour holding period. 

EPA’s Reevaluation of Data and Response to Data Selection Comments

In response to comments with data selection concerns, EPA performed a comprehensive review 

of the available data sets. As explained in the proposal’s Technical Development Document 

(TDD) Chapter 11.B, EPA examined 170 documents for potential data sets to use as the basis of 

the proposed IM standards. In its reevaluation of the data, EPA compiled the data received in 

comments, and solicited data from commenters that claimed to have additional data supporting 

their position. After receiving all data, EPA reviewed the 207 newly received documents for 

potential data sets. As explained in the preamble to the final regulation and in Chapter 11 of the 

TDD, EPA revised its data selection criteria so that the final rule’s IM performance standard is 

based upon a larger set of data, number of facilities, and broader geographic region than used for 

the proposed standards. EPA considers facility level performance to be a critical factor in 

determining the annual average standard. By revising the data selection criteria, EPA is able to 

include more facility level data in its calculations; thereby addressing commenters concerns that 

it is too limited (e.g., geographic area, environmental conditions, species, etc.) while ensuring the 

limits represent the BTA technology basis. The resulting data set contains data from 17 facilities 

Essay 16A 132 
with traveling screens with post-Fletcher modifications. The 17 facilities collectively provided 

data for facilities in 11 states and more than 1500 sampling events beginning as early as 1977. 

Other commenters continue to take the position that EPA did not collect sufficient data. EPA 

disagrees. For more than 10 years, EPA repeatedly requested the industry to provide data for the 

model technologies and explained its rationale for requesting the data, including but not limited 

to requests in the Phase II rule, the Phase III rule, this proposed rulemaking and the subsequent 

NODA. In the EPA’s view, numerous opportunities to collect data and provide information over 

the last 10 years provides additional support that the actual data in front of the EPA at this time is 

both representative and appropriate and is the best available. In developing the final regulation, 

EPA used all available relevant data to maximize the number of facilities, geographic regions, 

waterbodies, seasons, species, holding times, and years present in the data. EPA has all available 

data, even if the data is limited, with which to set the standards, thus EPA’s approach is 

reasonable. See e.g., BASF Wyandotte Corp. v. Costle, 598 F.2d 637, 652-653, (1st Circuit, 

1979). 

Some commenters advocated inclusion of specific data in the calculations, such as data from 

particular facilities along the West Coast or Hawaii, or specific facilities. Commenters suggest 

inclusion of their chosen data would address concerns over variability between locations. 

Contrary to assertions in comments, EPA has not seen any patterns in the data underlying the IM 

performance standard that suggest performance varies by waterbody types that would possibly 

affect operations of the model technologies on the West Coast (or other geographic areas). Nor 

do comments identify any factors that might influence performance of the model technologies by 

geographic region or submit any data to support this assertion. In selecting data as the basis of 

the IM performance standard in the final rule, EPA applied its criteria to data from all locations. 

Because none of the data from West Coast or Hawaiian facilities met EPA’s final data criteria, 

none was included in calculating the IM performance standard. Upon further review of the 

specific species identified in the data obtained from the West Coast or Hawaiian facilities, EPA 

finds that similar species (same Genus or family, for example) are indeed represented in the data 

from the 17 facilities. As another example, the EPA eliminated the proposal requirement that 

species must be typical of the location. This provision excluded certain data from the Salem 

facility. However, the documentation for the Salem data identify them as estimates (Ronafalvy 

(2000, page S381 refers to the IM as “estimate average proportion”) and EPRI (2007, e.g., Table 

2-12 labels all survival rates as “estimates” on page 2-29)). As explained in TDD Chapter 11, the 

selection criteria required that the data were actual measurements, and not estimated data. 

Therefore EPA did not include these data in its calculations. See TDD for more information. 

Some commenters suggested EPA created data for calculating the performance standard. EPA 

disagrees that it has in any way artificially created the data used as the basis of the IM 

performance standard. It has based the IM performance standard upon sampling events 

conducted and reported by others. These data sets are in the record. EPA has applied widely 

accepted statistical procedures in aggregating the data and developing the 12-month performance 

standard. Comments express concerns that percent IM from different sampling events at a 

facility may be statistically related to one another (i.e., not independent); however, EPA modeled 

the IM performance standard, not the individual sampling events. EPA need only consider 

independence between the mutually exclusive, approximately 12-month periods in the data from 

Essay 16A 133 
each facility. When data are said to be positively autocorrelated, it means that measurements 

taken at specific time intervals (such as 1 day or 2 weeks apart) are related, and thus, not 

independent. To determine if autocorrelation exists in the data, a statistical evaluation is required 

using many measurements for equally spaced intervals. With the data provided by industry, all of 

which cover relatively short time periods, it is not possible to conduct a rigorous evaluation of 

independence of facility performance from year to year. However, EPA considers its influence 

on the value of the final IM performance standard to be minimal based on its autocorrelation 

analyses using all available data that meets the requirements of such analysis. Although many 

facilities provided data collected for more than 12 months, it was possible to separate the data 

into separate (approximately) 12-month periods for only one facility (such as data for Somerset). 

After separating the Somerset data into two 12-month periods, EPA averaged the two values to 

obtain a single value for Somerset to use in the statistical modeling. Any effect of dependence 

between Somerset’s two IM rates would have been minimal because EPA used their average, not 

the two separate values, in the statistical modeling. In addition, Somerset’s data would not have 

had an undue influence on the value of the final IM performance standard because it provided 

only one of the 17 annual average values used in the statistical modeling to determine the final 

IM performance standard, and not 2 of the 17 as suggested by commenters. 

For the proposal and final rule, EPA cites certain studies as described in second-party reviews 

conducted by EPRI; however, EPA did not rely solely on the second-party reviews. EPA 

appreciates the reviews conducted by organization such as EPRI, and used such reviews to 

obtain additional original studies. These studies are in the record, and were used to glean 

additional information about the studies conditions and the technologies reviewed. Although the 

second-party reviews generally presented fewer details, they consolidated the results in a format 

that facilitated EPA’s data extraction. To avoid the appearance of having double-counted data 

sets, EPA cited only the second-party reviews and provided references to their consolidated 

tables. 

Specifically, EPA reviewed three studies for the Huntley, Roseton, and Arthur Kill facilities 

because comments asserted that EPA had incorrectly incorporated their data into the proposal’s 

standards database. For the Huntley study from 1999, a comment expressed concerns about 

EPA’s use of the data, and suggests that Huntley could not meet the performance standard that 

based on Huntley’s own data. EPA disagrees. Contrary to the comment’s assertion, Huntley’s 

data with an average percent IM of 1.6 percent demonstrates better control than would have been 

required by either the proposed annual performance standard and certainly the final IM 

performance standard. Commenters do not describe how any perceived shortcomings in 

Huntley’s study would have affected the performance data. For example, although Huntley 

shortened its planned sampling time and did not sample for the entire 12 months, EPA has 

determined that the study still provides IM data that reflects the performance of the model 

technologies over the course of an entire year. See the TDD for further discussion of the criteria 

for long term data collection. Because the Huntley data meet the revised criteria and commenters 

have provided no data to the contrary, EPA has appropriately continued to include the data from 

1999. For the Roseton study, comments identified data as coming from a document that does not, 

in fact, contain data for Roseton. The comments refer to Micheletti, W. and J. Burns, Estimating 

Energy Penalties for Wet and Dry Cooling Systems at New Power Plants (2003) (EPA Docket 

OW-2002-0049 DCN 6-5046H). After reviewing its record index (the DCN and report title refer 

to different documents), EPA concluded that the comment refers to the DCN, and not the cited 

Essay 16A 134 
report. The cited report was not provided to EPA. DCN 6-5046H is a document by Johnson and 

Moser entitled “Fish Return System Efficacy and Impingement Monitoring Studies for JEA’s 

Northside Generating System.” In conclusion, EPA agrees that the data from this report are for 

JEA Northside, and not Roseton, and has corrected its database. For the Arthur Kill study, 

another comment questioned the values shown in Exhibit 11-4 of the TDD. The comment 

appears to only have considered data from Table 4 of the Arthur Kill study. However, the Arthur 

Kill study also provides data in Table 7 which were collected from the same screens and 

sampling event as the data from Table 4. Thus, EPA has appropriately combined the data from 

the two tables in the Arthur Kill study Exhibit 11-4. 

Comments identify three studies, Fletcher (1986 and 1990) and McLaren and Tuttle (2000), as 

additionally relevant to the proposed performance standards development. The comments also 

recommended that EPA change its data selection criteria so that IM data from these studies could 

be included in developing the final IM performance standard. However, despite a follow-up 

request, the commenter did not provide EPA with a copy of Fletcher (1986), and therefore, EPA 

could not evaluate that set of data. EPA disagrees with the other comments. EPA finds the final 

criteria are appropriate; see TDD Chapter 11. Specifically, inclusion of data from lab studies are 

not appropriate because these data do not reflect the same operating conditions in which the 

technologies are actually employed, such as trash and debris loading and weather events. While 

it is an important study of traveling screens, Fletcher’s 1990 study does not contain any IM data 

because its focus is on engineering and efficiency aspects. EPA’s evaluated the McLaren and 

Tuttle report from 2000 (for the complete citation, see Document ID 64 in TDD Chapter 11, 

Appendix A). Because the data in this report for Somerset meets the final rule data selection 

criteria, EPA incorporated the Somerset data from Table 3 into the standard database. It excluded 

the data from Table 5 because the data represent a period longer than specified in the criterion 

(i.e., approximately 12 months). EPA also notes that its record includes a second report by 

McLaren and Tuttle. This report is undated, but assumed to be 1999, and presumably an 

unpublished report, identified as Document ID Study 244 in TDD Chapter 11, Appendix A. Both 

the 1999 and 2000 reports contain the same tables of IM data collected from the Somerset 

station. 

EPA disagrees with comments that assert that laboratory and modeled data can be used to 

determine the relative strength of species, informing decisions about the likely survival 

achievable in the field, especially when data for certain species are limited or unavailable. EPA 

continues to be concerned that laboratory and modeled data may not represent the real world 

results of BTA. For example, EPA has identified that low rates of fish catch may inadvertently 

increase fish mortality, poor fish condition prior to their use in collection results in poor survival, 

and some studies used techniques such as a “crowder” or other means employed for purposes of 

forcing fish to impinge or be collected; these data are not representative of actual technology 

performance. Regardless of the availability of data for particular species, the comments have not 

provided convincing evidence that laboratory and model data would appropriately mimic the 

performance of the model technologies under normal conditions. 

EPA agrees that data from a wider range of holding times are appropriate for inclusion in the IM 

database used for the IM performance standard in the final rule. EPA reevaluated both the old 

and new data using an expanded holding time criteria range of 18 hours to 96 hours which 

increased the number of facilities present in the final database. Several studies demonstrated 

Essay 16A 135 
impingement duration and holding times were not critical factors affecting survival for many 

species. The majority of the data used was from studies with holding times of 48 to 96 hours, 

with only four studies having holding times of 18 to 24 hours. In studies that assessed survival at 

multiple intervals, EPA used only the data from the longest period within the 18 to 96 hour timeframe. EPA excluded data for periods shorter than 18 hours since some lethal injuries due to 

impingement will not be immediately apparent. None of the data and comments provided 

indicates this is no longer the case. However, in light of the other comments and data, EPA 

agrees that holding times are no longer a critical factor, at least not for the species identified in 

the data. For these reasons, for the final regulation EPA has revised the criteria by expanding the 

range of mortality monitoring holding times from 24 to 48 hours to 18 to 96 hours, and has 

further specified that the Director may establish alternative holding periods. In the absence of 

data upon which the Director may determine the appropriate holding time, EPA’s analysis 

suggests a minimum of 48 hours is most appropriate to ensure that the facility observes the 

majority of initial and latent mortality associated with impingement. See DCN 10-6709 for 

additional discussion. See also TDD Chapter 11 and Section V of the preamble for additional 

information. 

EPA disagrees that comments asserting that the proposal documentation was deficient or that 

EPA fabricated data for calculating the performance standard. All studies and data are in the 

public docket. Proposed Chapter 11 describes EPA’s thorough, consistent, and unbiased review 

of the data and all supporting documentation accompanying the data. The final TDD Chapter 11 

documents EPA’s additional and thorough review of its data for the final rule. EPA performed 

the reviews to ensure that the selected data represent IM and that the data reflect the performance 

of the model technologies. The EPA used as much data as possible, only rejecting data that do 

not meet the acceptance criteria. By identifying these criteria, the study documents, and the data, 

EPA considers its data selections to be easily reproduced by using information in the public 

docket. While the EPA did not identify all criterion by number for each and every study, both the 

proposed and final TDD Appendix 11-A provide one or more reasons for data exclusions for 

each study. As discussed above, those studies that did not meet EPA’s acceptance criteria can 

still be used to demonstrate the 12-month performance standard is achievable. 

Statistical Methodology

Appendix D to Chapter 11 of the proposal TDD provides details on the EPA’s choice of the beta 

family of distributions, and section 11D.2 discussed alternatives to the beta distribution 

(including the normal distribution model, nonparametric approaches, and survival analysis 

approaches) for modeling percent IM. The documentation demonstrate that the EPA considered 

alternatives and, upon doing a statistical assessment of each, determined that the beta family of 

distributions was the best approach to take given the objectives addressed in the proposal. 

Despite earlier evaluation of the statistical methods, the EPA re-evaluated possible alternatives. 

This section of the essay describes the comments and the EPA’s response regarding reevaluation 

of its statistical methodology. 

Comment Summary

EPA based the value of the proposed annual average standard and final 12-month IM 

performance standard upon the expected value of the beta distribution determined from the IM 

Essay 16A 136 
percentage data from facilities with BTA technology. The median of the facility averages 

provides the same value as the expected value from the beta distribution. Many comments argue 

that the application of a beta distribution was not appropriate for the data set used by EPA. They 

claim that EPA provides no basis for selecting and fitting the beta distribution and the 

distribution over-aggregates the data so that the actual variation is neglected. Comments also 

argue that the “fit” of the data to the beta distribution provides very little assurance that the 

distribution is predictive of conditions outside of the data set. Comments also question EPA’s 

use of method of moments (“MOM”) estimation, because of what commenters consider a small 

sample size. Comments assert that EPA still should have incorporated a standard deviation, 

confidence interval, or variability factor not only in monthly averages, but in the annual average 

standard. 

EPA did not consider comments related to the statistical basis of the monthly average standard 

because they are not relevant for the final rule. For example, EPA did not consider comments 

about the perceived lack of EPA analysis to back up the assumption that the monthly IM 

observations would be distributed about the expected average as suggested by the beta 

distribution. 

EPA’s Reevaluation of the Statistical Methodology and Response to Statistical

Comments

In developing the final IM performance standard, in light of the comments that it had received, 

EPA again considered several parametric methods and the nonparametric approach to model the 

data used as a basis of the proposed annual average standard. Because of their concerns about the 

capability of facilities to meet the proposed standard, comments suggest that EPA reject the beta 

distribution and use methods that would incorporate additional variability in the standard 

development. For the reasons explained below, EPA disagrees that the recommended alternatives 

are appropriate and has confirmed its choice of the beta family of distributions as a reasonable 

choice to use as the basis for the IM performance standard in the final rule. 

For the first alternative method, comments suggest that EPA develop a performance standard that 

would allow for exceedances. EPA disagrees that such an approach is appropriate for several 

reasons. First, the IM performance standard applies to the average observed during a 12-month 

period, and not to individual monitoring events during that period. By actively evaluating 

ongoing performance during the 12-month period, a facility can optimize the equipment to 

improve performance to counterbalance a result above the standard by one below the standard. 

Second, allowing periodic exceedances would be a disincentive for ongoing maintenance and 

operations of the BTA. Third, the approach could have a seasonal effect on percent IM. For 

example, if a facility claimed its allowable exceedance during spawning season, a poor IM 

percent could result in large numbers of young organisms dying than during non-spawning 

seasons. Courts have agreed with EPA’s rationale in similar situations. For example, the 2nd 

Circuit Court ruled that denying excursion provisions justifiably compels the industry to develop 

the technological capability necessary to avoid excessive discharges. Accord, United Steel Corp. 

v. Train, supra, 556 F.2d at 842. 

For the second alternative method, comments recommend that EPA consider a statistical 

tolerance limit. In referring to a 95 percent analysis around a mean or average value of the data, 

Essay 16A 137 
comments are referring to a tolerance limit, or confidence limit, which is not a point estimator 

but rather an interval estimator having the property of being larger than the desired quantity with 

a stated degree of statistical confidence. Comments incorrectly assert that EPA had developed 

the proposed monthly average standard using such an approach. As explained in the proposal 

TDD, the EPA calculated the 95th percentile of the distribution of monthly averages. Interval 

tolerance limits also are based on accepted statistical methods; however, they are designed for 

special applications in which it is critically important to obtain an upper bound on a quantity and 

in which the cost of substantially overestimating that quantity is small. EPA has determined that 

basing the final IM performance standard on a tolerance limit would be inappropriate and would 

allow mortality rates that would greatly exceed the consistently observed performance of the 

model technologies. While EPA considers facilities that properly operate and control the model 

technologies capable of complying with the IM performance standard, as discussed above EPA’s 

final rule approach requires optimized operation, and a tolerance limit is not necessary. 

For the third alternative method, comments assert that EPA is required to apply a variability 

factor in developing the standard. In developing limitations for effluent guidelines, EPA 

approximates the percentile basis of daily and monthly limitations using long-term averages and 

variability factors based upon pollutant concentration data. For the final rule here, EPA is 

establishing an IM performance standard using a different methodology to better model percent 

IM data. In addition, the variability factor would provide an upward adjustment to the IM 

performance standard that EPA does not consider necessary for a value that facilities need only 

comply with on an annual basis. 

After considering and rejecting the three alternatives, EPA reevaluated and reaffirmed use of the 

beta distribution as still appropriate in developing the final IM performance standard. An 

advantage of the beta family of distributions is that it provides parametric methods for 

statistically evaluating the distribution of data. Parametric methods require that a probability 

distribution be specified and this allows estimation of unknown parameter(s) from the available 

data using maximum likelihood or an alternative estimation methodology. Parametric methods 

apply a series of mathematical equations to the data to obtain estimated parameters. In this 

manner, the estimated parameters are a function of the defined distribution and the data. In 

contrast, nonparametric statistical procedures rely on no or few assumptions about the shape or 

parameters of the underlying distribution. EPA prefers the parametric approach because it uses 

all of the available data to estimate the distributional parameters, which in turn, are used to 

estimate the value of the IM performance standard. 

A second advantage is that the beta family provides EPA with reasonable flexibility in modeling 

the data. The beta family of distributions provides considerable flexibility in modeling the IM 

percentages because it is not a single distribution (as commenters were implying), but instead, 

represents many distributions that can take on a variety of shapes. Appendix D.1 in Chapter 11 of 

the proposal TDD shows several of the possible shapes within the beta family of distributions. 

Unlike the distributions such as the normal distribution, the beta family is not limited to 

symmetric, bell-shaped, and unimodal forms. Because it uses all available data to model the 

distribution, each beta distribution allows for the maximum use of the available data from a 

facility. When applying the beta distribution to a set of data, there is no need to verify that the 

data are distributed about the average of the distribution because each fitted beta distribution is 

not constrained to one particular shape (unlike the normal distribution) as it originates from a 

Essay 16A 138 
broad family of distributions. Therefore, the fitted distribution will closely match the shape 

observed in the data. Thus, for this reason and because it used all available data that met its 

criteria for performance data associated with BTA, EPA disagrees with comments that assert that 

the “fit” of the data to the beta distribution provides little assurance that the distribution is 

predictive of conditions outside of the data set. 

A third advantage is that the beta family constrains the data in the same manner as the observed 

data. The beta distributions are continuous in nature, which also holds for the percentages of IM. 

IM percentages can be expressed as proportions that can take on any value between 0 and 1, 

which is the range covered by the beta family of distributions. In contrast, the lognormal 

distribution, suggested by comments as a more appropriate distribution, does not have a finite 

upper bound that is inherent with IM percentages (i.e., 100 percent is the upper bound). 

A fourth advantage is that the specific form of the beta distribution, contrary to assertions in 

comments, accounts for the variability in each modeled facility data set. The specific form of the 

beta distribution was determined by the observed data (when expressed as proportions of IM). 

The method of moments (MOM) fitting of the beta distribution to the data utilizes both the 

observed average and the observed standard deviation (which is calculated as the square root of 

the variance) of the facility’s data points in determining the parameters of the beta distribution. 

Thus, the actual variation in the data is accounted for in determining the specific form of the beta 

distribution for each facility data set. 

EPA also considered the issue of sample size in applying the beta distribution. Comments assert 

that economic literature frequently discusses the inapplicability of the MOM estimation approach 

for small sample sizes and emphasizes that small samples result in biased estimators and 

inaccurate confidence intervals. EPA is familiar with the economic literature and disagrees with 

the conclusions that the comments attribute to the literature. Bias and lack of accuracy are not 

introduced to estimators exclusively by small sample sizes; rather, small sample size is 

associated with higher uncertainty (i.e., theoretically lower precision) in estimation. Thus, while 

small sample size is associated with larger standard errors in most traditional estimation 

techniques, the sample size and the MOM estimation approach do not inherently lead to biased 

or inaccurate estimates. In any case, EPA has increased the number of data points in the standard 

database and has used all of the relevant data available to it in developing the final standard. For 

additional explanation about EPA’s efforts to maximize the sample size, see the section “EPA’s 

reevaluation of data and response to data selection comments.” EPA also notes that the 

comments expressed concern about the size of the database, but did not explicitly identify the 

number of data points that they would find to be acceptable for EPA’s calculations. 

The MOM estimation approach is one of several ways to estimate the two parameters of the beta 

distribution from observed data. The advantage of MOM is that it is straightforward to calculate 

from closed-form equations. A disadvantage is that the MOM can yield estimates that are outside 

the range of possible parameter values, though this did not occur in developing the final IM 

performance standard (i.e., the estimates of both parameters of the beta distribution were greater 

than zero). After considering these advantages and disadvantages of the MOM, Maximum 

Likelihood Estimation (MLE), and Bayesian estimation procedures, EPA concluded, contrary to 

assertions in comments, that the MOM was the best approach because it provided consistent 

estimates from closed-form equations that can be used by others to readily and transparently 

Essay 16A 139 
reproduce the value of the standard. EPA rejected the MLE and Bayesian approaches as 

explained in the following paragraphs. 

For the MLE approach, EPA considered its use instead of the MOM because its parameter 

estimates are always within the range of possible parameter values. A disadvantage of MLE is 

that no closed-form equations for the beta distribution exist, and therefore, iterative algorithms 

would need to be used. As a result, these algorithms may not always converge to a global 

maximum, and persons using different implementations of the MLE algorithms might arrive at 

different estimates. For this reason, EPA rejected the MLE approach because different 

applications might not result in the same, consistent, value for the standard. 

For the Bayesian estimation approach, EPA was concerned about its requirement for either a 

subjective choice of a prior distribution or the use of a non-informative uniform prior; in the 

latter case, the result would be the same as the MLE that EPA previously rejected (as explained 

in the previous paragraph). EPA rejected a subjective choice of a prior distribution because it 

requires a judgment call in selecting a distribution. Therefore, while EPA agrees this approach is 

a possible alternative, this approach did not represent the best approach available here. 

In addition to evaluating the statistical methodology, EPA evaluated whether the statistical 

methodology over-aggregates the data, as comments asserted. To ensure that it was basing the 

final IM performance standard upon appropriate data, EPA aggregated the data within each 

facility into mutually exclusive periods of approximately 12 months or less, as explained in the 

TDD. To ensure that any one facility did not have undue influence on the IM performance 

standard, EPA then aggregated across multiple periods. In this manner, EPA based the IM 

performance standard upon the facility annual averages by using appropriate aggregation of data 

collected during individual monitoring events. EPA concluded that its aggregation approach used 

for the proposal was appropriate and has used the same approach in developing the final IM 

performance standard. 

After confirming its earlier choice of the beta distribution for the IM data, EPA applied the 

proposed methodology to develop the IM performance standard using all of the available and 

relevant data from the facilities using the model technologies. The next section addresses 

concerns with achievability and compliance with the IM performance standard. 

Achievability and Compliance Issues

As explained in the previous section, EPA considers the beta distribution to be appropriate for 

modeling the percent IM data, in part because it incorporates the variability in the data, and has 

used the method of moments (“MOM”) to estimate the parameters of the beta distribution. The 

regulation establishes the IM performance standard as a maximum value that facilities are not to 

exceed, on average, in any 12-month period. This section of the essay addresses concerns about 

achievability and compliance of the IM performance standard. In this section, EPA responds to 

comments recommending further flexibility in complying with the rule; achievability by 

facilities used as the basis of the IM performance standard, all facilities, and facilities with low 

numbers of impinged fish; and optimization of the technology selected for BTA. 

Comments suggest that EPA develop alternative compliance strategies for the situation when 

achieving the IM performance standard would not be feasible. For example, one comment 

Essay 16A 140 
suggests that the state permitting authority should have the flexibility to set mortality rates that 

may be variable from month-to-month, or to include only an annual average. As another 

example, another comment points to EPA’s consideration of WET limits during its rulemaking. 

EPA notes the commenter incorrectly interprets EPA’s regulation as being a trigger for further 

sampling and evaluation, not as a pass/fail standard, because of inherent variability in attempting 

to sample and measure natural systems. Although the comment is incorrect about WET limits 

being triggers because they are enforceable standards, EPA considered the comment’s concept of 

using triggers to require additional monitoring of ongoing performance. First, for the reasons 

explained above, EPA disagrees that the IM performance standard is not feasible. Second, the 

final rule includes seven compliance alternatives for the IM standard, only one of which requires 

biological compliance monitoring to demonstrate the IM performance standard is met. See Essay 

16. For those facilities that elect to comply with one of the pre-approved or streamlined IM 

compliance alternatives, EPA agrees that it is not necessary to require biological compliance 

monitoring. See Essay 16. Further, because EPA’s final rule does not require biological 

compliance monitoring in perpetuity for 6 of the 7 compliance alternatives, EPA’s approach 

offers the benefit of “streamlined” compliance; see final rule at 40 CFR 125.94(c). 

Comments claim that EPA’s approach produced a proposed annual average performance 

standard that could not be met even by those facilities on which the standard was based. Many 

comments argue that 50 percent of the BTA facilities cannot meet the proposed annual average 

standard because EPA based its value on the average performance of all BTA facilities. EPA 

disagrees that it has promulgated an IM performance standard that BTA technology cannot 

achieve on a regular and ongoing basis. The IM performance standard is not designed to validate 

current practices but rather to control intake structures within prescribed limits. EPA applied 

statistical methods to develop the IM performance standard using all of the available and relevant 

data from the facilities using the model technologies. EPA notes that not all studies included in 

the database were using technology optimized for the purposes of meeting the IM performance 

standard; such facilities, upon optimizing their technology performance, are expected to exceed 

the level of performance identified in the studies. As discussed above, because the IM 

performance standard is based upon data collected from facilities applying the model 

technologies, it already incorporates all sources of variability within the data. For facilities 

choosing to comply by alternatives § 125.94(c)(1) through (4), the technology performance 

exceeds that of the IM performance standard and the comments are irrelevant. For facilities 

choosing to comply by alternative § 125.94(c)(5) using EPA’s model BTA technology (modified 

traveling water screens with fish handling and return), the final rule requires a 2-year 

optimization study to be used to establish permit conditions that are indicative of the site-specific 

optimized operation of the technology. Such facilities will not use biological monitoring to 

demonstrate ongoing compliance. Similarly, under § 125.94(c)(6), the 2-year study 

demonstrating a system of flow reductions, reduced rates of impingement, and other practices 

will be used to establish permit conditions that are indicative of the site-specific optimized 

operation of the technology. Again, such facilities will not use biological monitoring to 

demonstrate ongoing compliance. See preamble for more details. 

EPA expects that few facilities, estimated at less than 1 percent of all facilities, primarily those 

with new and innovative control technologies not already addressed by the IM compliance 

alternatives in § 125.94(c)(1)-(6) will comply with the standard via § 125.94(c)(7) and conduct 

biological compliance monitoring. Because EPA expects this compliance alternative may be 

Essay 16A 141 
chosen by facilities are not using the IM BTA, these facilities must achieve an average 

performance level that facilities with well-designed and operated model technologies (i.e., the 

top 50 percent) have demonstrated can be done. 

There are numerous studies in the record that were not included in the database because they did 

not meet all acceptance criteria. These studies, while not meeting all of EPA’s criteria, show the 

technologies are widely available, demonstrated, and capable of achieving the IM performance 

standard. For example, a study may have included some instead of all the fish protection 

features, or may not have included 12 months of data – and yet the performance in these cases is 

consistent with that required in the final rule. EPA notes these additional studies do not suggest 

that a more stringent performance standard is warranted and that EPA should therefore revise its 

acceptance criteria, rather these studies show EPA’s model technology is demonstrated, 

available, and performs in a consistently high manner. 

Comments question how facilities would demonstrate compliance with the monthly and annual 

average performance standards. As described above, the monthly standard is not included in the 

final rule so no response is required. The facility would calculate the 12 month average by using 

the arithmetic average of its percent IM observed in monitoring events each month in the 

proceeding 12-month period. See the preamble for additional information. 

Comments express two concerns regarding compliance with the annual average standards when 

the facility has low rates of impingement. One concern is that the proposed standard did not 

account for technologies and operational measures that may have contributed to low 

impingement. Another concern is that those facilities with low impingement would have 

difficulty complying with the IM performance standard if the number of impinged fish are so 

low that the mortality percentage could vary widely just with the fate of relatively few fish. 

Comments add that the expression of the IM performance standard as a percentage of impinged 

organisms is highly problematic, as it would require mitigation even when absolute counts of 

killed fish are very low. Other comments state that EPA did not propose a methodology that 

could accommodate widely varying sample sizes (e.g., 10 versus 1000) when calculating annual 

and monthly survival performance. EPA agrees that the proposed standard did not accommodate 

facilities that observe few fish impingements because the only situation where that occurs is 

when the facility has adopted other measures to actively avoid or reduce fish impingements. EPA 

solicited comments on this aspect of the proposal, and issued a NODA that included possible 

approaches to this concern (77 FR 34322). In the case of the commenter data with just a few fish 

impinged, EPA notes the facility has low rates of impingement due to the off-shore velocity cap. 

Thus the facility could demonstrate compliance under section § 125.94(c)(6) without other 

controls. In the NODA (77 FR 34322) and the final TDD Chapter 11, EPA describes the 

calculations to incorporate credit for existing or newly installed technologies. In addition, the 

final rule allows the Director, based on review of site-specific data and where no threatened or 

endangered species may be present, to conclude that, where few fish are likely to be impinged, a 

de minimis rate of impingement exists and therefore no additional controls are warranted to meet 

the BTA IM standard. 

Some comments argue that EPA based the proposed standards on a flawed assumption that a 

single technology (i.e., traveling screens with fish return capability or the equivalent) is capable 

of reliably achieving the same level of protection regardless of the location, relative abundance 

Essay 16A 142 
of individual fish species within and between years, or differences in the aquatic environment. 

Comments state that a facility could expend a considerable amount of money installing 

technology without any assurances that the prescribed technology could meet the IM 

performance standard. Comments also claim that operators would not be able to innovate and 

optimize the operation and configuration of their traveling water screens to achieve reduced rates 

of IM because facilities can modify and optimize very little on a modified traveling water screen. 

They note that nowhere in the record does EPA point to evidence to support its assertions about 

optimization. EPA disagrees with these comments. As discussed above, the BTA model 

technology is demonstrated, available, and achieves a consistent level of performance. Site visits 

in EPA’s record show facilities can and do strive to optimize their modified traveling screen 

performance. Other comments from actual facilities provide data showing that the model BTA 

technology can in fact be optimized. These commenters suggest possible operating parameters 

subject to modification would include: 1) rotation speed; 2) rotation frequency (e.g., intermittent 

vs. continuous); 3) spray wash pressure; and 4) spray wash angle. Other comments question 

EPA’s assumptions in the proposal that these parameters could be adjusted to maximize fish 

survival. Studies in the record support EPA’s claim that optimized values exist for the operating 

parameters, including a number of lab studies that successfully focus on one operating parameter 

at a time. EPA disagrees that it is impossible to optimize performance to meet the IM 

performance standard in the final rule. The final preamble, and the final record, cites several 

examples including site visits and examples provided by industry in comments (e.g., Energy 

Information Administration). Optimization requires study and modifications which are inherently 

part of proper operations and maintenance, which EPA has included in its costs of the rule. The 

final rule establishes seven alternative methods for complying with the IM BTA standard. One of 

these methods involves employment of a modified traveling screen that meets certain design 

characteristics and has been demonstrated to be operated in an optimized manner through 

biological monitoring during a 2 year optimization study. As discussed above, EPA expects that 

once the technology operation is optimized, its performance would exceed the IM performance 

standard, and the EPA has therefore streamlined compliance by eliminating biological 

monitoring after the optimization study. See the preamble for additional details and the record 

for the literature studies that describe technology optimization. 

Public Review

EPA disagrees with comments that assert that further public review and comment was necessary 

for the revised performance standards. The proposal documentation clearly describes the 

methodology EPA used to derive the proposed annual average performance standard. EPA 

clearly provided notification of EPA’s consideration of revising the standards based on new data 

in the NODA at 77 FR 34317 Col. 3. The data and methodology used is available in the record 

allowing the public to independently calculate and verify the final IM performance standard. 

Nothing prohibits the Agency from adding supporting documentation for a final rule in response 

to public comments. In fact, adherence to the commenter’s view might result in the EPA’s never 

being able to issue a final rule capable of standing up to review: every time the Agency 

responded to public comments, such as those in this rulemaking, it would trigger a new comment 

period. Thus, either the comment period would continue in a never-ending circle, or, if the EPA 

chose not to respond to the last set of public comments, any final rule could be struck down for 

lack of support in the record. Cf. BASF Wyandotte Corp. v. Costle, 598 F.2d 637, 644-45 (1st 

Cir. 1979) (noting that it is “perfectly predictable” that an administrative agency will collect new 

Essay 16A 143 
data during the comment period “in a continuing effort to give the regulations a more accurate 

foundation” and stating that “the agency should be encouraged to use such information in its 

final calculations without thereby risking the requirement of a new comment period”), cert. 

denied, 444 U.S. 1096, 62 L. Ed. 2d 784, 100 S. Ct. 1063 (1980), later proceeding, 614 F.2d 21 

(1st Cir. 1980) (dismissing petitions for review). Also see Cf. Chemical Mfrs. Ass’n v. EPA, 870 

F.2d 177, 200-02 (rejecting argument that agency was required to reopen notice-and-comment 

period before relying on economic data updated and expanded after the close of a comment 

period), clarified, 885 F.2d 253, later proceeding, 885 F.2d 1276 (5th Cir. 1989) (concerning 

attorneys’ fees).
 

Essay 16A 144 
Essay 17: Intake Velocity

Introduction

Many commenters expressed concern that operation of a cooling water intake structure that does 

not exceed the prescribed through screen design velocity may be difficult to achieve at many 

facilities or that the costs to comply would be high. Commenters also considered the 0.5 ft/s 

design velocity to be over conservative, especially when applied as a through-screen velocity and 

also questioned the underlying rationale for selection of this value. Many had concerns regarding 

implementation. 

EPA agrees that 0.5 ft/s design velocity is not available for some facilities and that the 

compliance costs may be higher where the design velocity is difficult to achieve. EPA disagrees 

that a requirement for a 0.5 feet per second design velocity is inappropriate or improperly 

calculated as an alternative to comply with the impingement mortality performance standard. 

The record for today’s rule, as well as previous proposals and 316(b) rules, supports such an 

alternative requirement. Additionally, for the reasons explained in the preamble, EPA did not 

establish an impingement mortality requirement based on low velocity. It is one of seven 

alternatives available for complying with the BTA impingement mortality standard in the final 

rule. Consequently, compliance with a design velocity restriction is not required at all facilities. 

With the exception of issues and clarifications discussed below, EPA has addressed previously 

most of the issues raised with regards to intake velocity by comments on the proposal and 

NODA. EPA first prescribed a design velocity requirement as a compliance alternative in the 

Phase I Rule and it continued this approach in the Phase II, Phase III, and today’s existing 

facility rule. Under the Track I approach of the Phase I rule, a new facility had the choice of 

complying with velocity and capacity requirements. Many of the issues raised in the proposal 

and NODA public comments for the existing facility rule concerning the standard and its validity 

have been raised in previous comments. Many commenters have expressed concerns regarding 

technology availability and implementation particularly with respect to the method of 

determination and intake location where it is applied. 

Background

EPA first adopted a 0.5 ft/s design velocity as a maximum through-screen velocity requirement 

in the Phase I Rule. The design velocity was also adopted under Phase II as an option to comply 

with impingement mortality requirements. Under Phase III, a design velocity similar to that in 

Phase I was adopted for new offshore oil and gas extraction facilities. 

Previous Comments on Intake Velocity

Phase	 	I

A summary of significant comments and EPA’s response regarding the velocity standard in 

Phase I final rule may be found at section VI.E of the Phase I preamble. See 66 FR 65301/2 to 

Essay 17 145 
65304/1. Many of the issues currently being raised by commenters on the existing facility rule 

were also submitted under Phase I. 

Commenters have provided no basis for EPA to change its earlier conclusions that the 0.5 ft/s 

requirement is scientifically based, technically sound, protective of aquatic resources, and 

technically available and economically practicable as demonstrated by the fact that it is 

frequently employed at recently built facilities. 

Phase	 	 	 	 	 II and Phase III

The absence of a discussion of intake velocity in the major comments section of the preamble for 

the final Phase II and Phase III rules indicates that commenters did not raise any new or 

significant issues with respect to this approach for those rules. See 69 FR 41610 (July 9, 2004) 

and 71 FR 35018 (June 16, 2006) for a summary of the major comments on each of these rules. 

Previous Litigation on Intake Velocity

Phase	 	I

In the Riverkeeper I Decision (decided February 3, 2004), the court summarizes the Utility 

Water Act Group (UWAG) arguments that there is insufficient support in the record for Track I’s 

through-screen velocity limit of 0.5 ft/s and that the relevant velocity should be the approach 

velocity and not the through-screen velocity. The court notes EPA’s position that through-screen 

velocity is easier to measure, that many recently constructed facilities are designed to meet 

through-screen velocity limits, and that it provides a margin of safety. The Second Circuit 

concluded that EPA’s choice of velocity limit was reasonable. Riverkeeper, Inc. v. EPA, 358 

F.3d 174, 198-99 (2nd Cir. 2004). 

EPA’s Response

Nothing in the comments on today’s rule provided any basis for EPA to revise its earlier 

conclusions about the appropriateness of a specified design velocity in achieving reductions in 

impingement mortality and its suitability for inclusion as one alternative for meeting the BTA 

impingement mortality standard. 

Comments on the existing facility rule pertaining to intake velocity tended to be focused on three 

main aspects: the availability or feasibility of the 0.5 fps velocity, the derivation of the 0.5 fps, 

and how the 0.5 fps would be implemented. The sections below address these comments. 

Availability/Feasibility

Riverkeeper supported the inclusion of a velocity standard with a carefully crafted variance for 

those who cannot meet it and argues that EPA’s rejection of the 0.5 ft/s velocity as the primary 

national standard is illegal. They state that “EPA lacks a legitimate legal or evidentiary basis for 

rejecting the 0.5 ft/s velocity limit” questioning EPA’s assertion that it is not “available” stating 

that “analysis or evidence in the record to support a conclusion that reduced intake velocity is not 

capable of being implemented at all locations appears to be lacking.” EPA agrees that, where 

available, an intake velocity less than 0.5 ft/s is an effective IM reduction technology. EPA, 

Essay 17 146 
                                                            

 

however, disagrees that achievement of this low intake velocity is broadly available. In fact, as 

noted by Riverkeeper, only 18 percent of existing intakes could meet the 0.5 fps velocity with 

existing technology. In order for an existing intake with a higher velocity to comply, they would 

need to either reduce flow or increase the screen surface area. Because many intakes have high 

screen velocities to begin with, the degree to which either the flow would be reduced or screen 

area increased could be considerable.14 These conditions may severely constrain or prevent 

particular locations from achieving the necessary velocity reductions required to meet a 0.5 ft/s 

velocity performance standard. Thus, EPA concluded that there would be a large number of 

intakes that may encounter difficulty complying with a low velocity performance standard. For 

these and other reasons, EPA rejected a 0.5 feet per second through-screen design velocity as the 

national BTA performance standard for impingement mortality. (See the discussion in Essay 15 

and Essay 16.) Rather, EPA included it as one of seven compliance alternatives for the BTA IM 

performance standard reflecting the performance of traveling screens with fish returns. 

More specifically, while EPA has identified a number of compliance technologies capable of 

achieving 0.5 fps, each has potential drawbacks. Ways to reconfigure or adapt existing intake 

structures to achieve a low velocity requirement where intake screen velocity is high include 

increasing the size of intakes, relocating and submerging the intake to an offshore location with 

wedgewire screens, variable speed pumps,15 and partial closed-cycle cooling. Larger intakes, 

wedgewire screens, and closed-cycle cooling are some of the most costly technologies 

considered by EPA and each may have restricted application in certain circumstances. The 

availability of wedgewire screens is limited by waterbody considerations such as water depth, 

sweeping velocity, and navigation interferences and, as such, applications tend to be limited to 

smaller intakes and the largest waterbodies. The availability of larger intakes is often limited by 

existing shoreline interferences (for example, where the shoreline is not owned by the intake 

facility; see Potomac Generating site visit report (DCN 10-6512) showing the shoreline property 

is part of a national park). Furthermore, increasing the intake size (three times for an average 

intake and five times or more for an older intake) may not be feasible due to a lack of available 

space at the intake structure. According to EPA’s record of acres owned, a facility with a 

shoreline intake that had to increase the existing intake structure by a factor of five or more will 

rarely have enough shoreline to be able to do so. For examples, see site visit reports for: East 

River (DCN 10-6506); Scattergood (DCN 10-6545); Haynes (DCN 10-6547); Crawford (DCN 

10-6544); Eddystone (DCN 10-6507); Sunoco (Philadelphia) (DCN 10-6542); and Potomac. In 

waterbodies that regularly contain high quantities of silt and sand, such as the Ohio and Missouri 

rivers, reducing the intake velocity creates problems regarding the deposition of sediment in the 

vicinity of the screens and in the channels/canals leading up to the screens. For example, see the 

site visit report for Nebraska City Station (DCN 10-6520). Silt and sand often require a certain 

sweeping velocity to prevent deposition as sediment. For example, a minimum of 2.5 to 3 ft/s is 

recommended to prevent deposition of sediment and sand in intake pipes for submerged offshore 

intakes (see Phase II TDD section 1.1.1). Such sedimentation may make it extremely difficult to 

maintain a low velocity in the vicinity and upstream of the screens effectively defeating the 

14 The average screen velocity for Phase II facilities was 1.5 ft/s and older screens were typically designed with a 

velocity of 2.5 ft/s. An intake with a velocity of 1.5 ft/s and 2.5 ft/s screen would need to reduce flow by 67 percent 

and 80 percent or increase the screen area by a factor of three to five times. 15 Variable speed pumps are only considered as viable for meeting a 0.5 fps velocity requirement for those intakes 

with a velocity already close to that value. 

Essay 17 147 
purpose of any low velocity requirement. Technology limitations are discussed further in TDD 

Chapter 6. EPA estimated that a total of only 34 percent of intake structures could comply with a 

velocity standard, including those that are already compliant. Thus, as noted, EPA has concluded 

that it should not establish low velocity as the national BTA for IM nor should it prescribe a 

nationally applicable low velocity IM performance standard. The identified constraints that 

restrict its application in numerous settings mean that low screen design velocity is not a 

nationally available technology. 

Riverkeeper also cites EPA’s rationale for including the velocity standard in Phase I as a 

rationale for including it as a primary national standard and points out that EPA’s supporting 

documentation for current rulemaking has stated that the velocity standard will reduce IM by 96 

percent, which is better than the selected technology (traveling screens). New facilities subject to 

Phase I are required to have intakes commensurate with closed-cycle cooling. According to 

EPA’s record, such intakes withdraw an average of 96 percent less volume of cooling water. 

Facilities with closed-cycle cooling (or retrofitting to closed-cycle) can design a new intake 

structure with a significantly smaller size than for once-through and still be able to meet the 

additional intake velocity requirement. The EPA agrees that a design velocity standard of 0.5ft/s 

is generally more effective at reducing impingement (and impingement mortality) than the 

selected basis for today’s IM standard. For this reason, the intake velocity is available as an 

alternative for meeting the BTA performance standard. However, as discussed above, the ability 

to retrofit an existing facility to meet such a velocity standard is not available at 66 percent of 

existing facilities. Also see the preamble and Essay 16A. 

Riverkeeper recommended that when applying a velocity standard, EPA should retain the 

additional fish return, fish entrapment, and shellfish barrier net requirements identified in the 

proposed rule. EPA agrees that 0.5 fps velocity is an effective IM reduction technology and has 

included it as one of several compliance options for meeting the BTA IM standard. For the 

reasons discussed in the preamble, EPA disagrees that the inclusion of other measures in addition 

to the 0.5 fps should also be a requirement of the low velocity IM compliance alternative. The 

record demonstrates that the 0.5 fps velocity alone, as well as the other IM compliance 

alternatives, will provide impingement reductions that achieve the required IM BTA 

performance standard. 

Other commenters expressed concern that 0.5 ft/s velocity standard was unachievable by many 

facilities, was not available at all facilities, and that there was no effective way to reduce velocity 

without expanding the size of the intake. Site-specific limitations such as gravity fed intakes will 

have limited options to comply. Commenters also argued that requiring that the maximum design 

through-screen intake velocity must be achieved under all conditions, including during minimum 

ambient source water surface elevations to include low flow conditions was too restrictive and 

cite multiple examples of existing intakes with velocities less than 0.5 ft/s that have been 

previously determined to employ BTA. As explained above, the EPA agrees that many existing 

intakes may not be able to comply with the 0.5 fps velocity without expanding the screen surface 

area by either expanding the intake or replacing the screen technology (e.g., using wedgewire 

screens) and that such options may be difficult and/or costly. In the final rule, EPA has 

established several alternative impingement mortality compliance options that facilities may 

choose as a means of compliance for each intake. EPA did not identify low flow as the basis for 

Essay 17 148 
the IM performance standard and facilities are not required to comply with a design 0.5 fps 

velocity. 

One commenter (EEI) also argued that requiring an “instantaneous maximum” design throughscreen intake velocity must be achieved under all conditions was inconsistent with how it was 

applied in Phase I and Phase II where velocity was averaged over the screen surface and noted 

that EPA revised the Phase I rule such that the velocity is derived using “[d]esign calculations 

showing that the velocity requirement will be met at minimum ambient source water surface 

elevations (based on best professional judgment using available hydrological data)....” 40 CFR 

125.86(b)(2). EPA disagrees that, when a facility chooses to comply with the IM performance 

standard with the 0.5 ft/s screen design velocity, it must achieve an instantaneous maximum. In 

the final rule, EPA has adopted the same language for defining minimum ambient source water 

as specified for monitoring velocity via head loss under Phase I at 40 CFR 125.86(b)(2). Also, 

EPA has provided the option of measuring through-screen velocity based on engineering 

calculations which allows for averaging the velocity over the entire screen surface. Also, shortterm exceedances of the 0.5 fps velocity may be permissible for brief periods (with approval 

from the Director) for purposes of maintaining the cooling water intake system, such as 

backwashing the screen face. EPA expects that facilities will employ appropriate design and 

operational measures to ensure that the maximum velocity is not exceeded during minimum 

ambient source water surface elevations, as can be anticipated through best professional 

judgment using hydrological data. 

Commenters argued that EPA should eliminate screen blockage requirements. EPA agrees that 

screen blockage requirements are unnecessary because the compliance alternative that is based 

on 0.5 fps velocity already includes a safety factor and therefore has removed them from the 

final rule; see next section for more information. Commenters argued that process water should 

be excluded. See Essay 14 for discussion of the applicability of IM requirements to process 

water. 

Derivation/Technical Framework

Commenters argued that EPA should remove any additional requirements (e.g., Ristroph 

features, counting fish carryover) if the 0.5 fps velocity is met and that those with closed-cycle 

cooling should not be required to meet it. EPA agrees that either the 0.5 fps velocity or closedcycle cooling alone will provide impingement mortality reductions that meet the performance of 

the BTA impingement mortality standard. EPA has revised the final rule so no additional 

technology measures are required for IM BTA compliance if the 0.5 ft/s velocity is met or for 

intakes that meet the definition of “closed-cycle recirculating system” at § 125.92. 

Commenters argued that the application of the 0.5 fps as the through-screen velocity was overly 

protective since it resulted in a much smaller corresponding approach velocity and that the 

approach velocity is more consistent with the underlying basis of swim speed. They note that an 

approach velocity has greater flexibility, less uncertainty, does not vary with screen porosity or 

penalize intakes with screens. EPA disagrees that the low velocity IM compliance alternative 

should be applied as an approach velocity. The original data used to support the 0.5 fps velocity 

was for fish swim speed, not approach or through-screen velocity; establishing the velocity 

threshold has nothing to do with whether EPA selects approach or through-screen, as it has to do 

Essay 17 149 
with setting a protective standard (greater or equal to the BTA IM standard) for a water velocity 

from which fish can escape. EPA’s position since Phase I has been that the difference between 

basing a velocity standard on through-screen velocity rather than approach velocity imparts a 

safety factor. This safety factor helps account for spatial differences that occur due to varying 

hydrodynamic conditions in and around the screens including varying degrees of debris 

blockage. This issue was also raised during litigation over the Phase I rule and the U.S. Court of 

Appeals for the Second Circuit sustained EPA’s position. 

Commenters noted that application of the 0.5 fps velocity as a through-screen velocity penalizes 

screens with fine mesh and may limit the availability of fine mesh as an entrainment technology 

for intakes that would meet the velocity intake with coarse mesh but not after replacement with 

fine mesh. EPA acknowledges that the application as a through-screen velocity has the perceived 

impact of penalizing intakes with screens and those with finer mesh, possibly limiting facilities 

compliance options. EPA has concluded that the most reasonable approach is to apply the 

standard uniformly and notes that facilities are free to select from multiple compliance 

alternatives including choosing a combination of technology “fixes” that will meet the BTA 

impingement mortality standards (see BTA impingement mortality standards alternative at 40 

CFR 125.94(c)(6)). This alternative allows facilities to aggregate partial credit for multiple 

existing technologies and provides a facility with the option to take credit for employing 

additional technologies or operational measures which can be particularly helpful if only an 

incremental reduction is needed to meet the IM BTA requirement. 

Commenters argued that there is no scientific basis for a low velocity screen requirement, that 

EPA misinterpreted the data in Phase I, and that the standard has no direct relationship to IM. 

EPA disagrees. As noted, these issues were also raised during development of the Phase I rule. 

EPA has seen no convincing evidence that contradicts its determination that reduced screen 

velocity has a significant effect in reducing and preventing impingement mortality. As 

previously noted, on a challenge to the Phase I rule, the Second Circuit determined that the 

record for that rule supported a through-screen velocity limit of 0.5 feet per second. 

Commenters argued that a screen velocity requirement should allow for consideration of sitespecific data such as susceptibility of species of concern or ocean environments where fewer 

poor swimmers may exist or demonstration that higher velocity is still protective. EPA disagrees 

that site-specific data should be used to modify the low velocity compliance alternative or its 

application. First, EPA has dropped the species of concern component from the final rule, and 

related comments are no longer applicable. Second, the low intake velocity IM compliance 

alternative is protective of all live stages of fish and shellfish that meet the definition of 

impingement (i.e., retained by a 3/8-inch sieve). While EPA agrees that some locations may 

exhibit fewer poor adult swimmers, EPA disagrees a higher intake velocity is appropriate. The 

record shows larval stages and early life-stage fish are not as strong swimmers as adults. (See, 

e.g., Boucher and Petrell, 1999, DCN 12-6971.) Some species have not yet fully developed their 

burst speed potential. In many species, swim speed correlates to body length (EPRI 2001). EPA 

concludes the 0.5 fps intake velocity is protective of multiple life stages. 

Commenters question whether complying using the 0.5 fps velocity is only appropriate for new 

facilities, which would have a chance to address the issue in design. As explained above, EPA 

agrees that it is not nationally available as a technology basis for IM requirements for existing 

Essay 17 150 
facilities. EPA disagrees that the 0.5 fps velocity is only appropriate for new facilities, and sees 

no reason why this velocity developed under Phase I should not apply to some existing intakes as 

well if a facility elects to do so. As explained earlier, this approach is only one of several IM 

compliance alternatives available and no existing facility is required to achieve compliance with 

the BTA impingement mortality standard by meeting a design velocity requirement unless it so 

chooses. 

Commenters noted that intake velocity is not defined in the same way as in Phase I. EPA agrees 

that it has modified the definition. These changes allow for greater flexibility for existing 

facilities in complying with the BTA impingement mortality standard through the design velocity 

approach. For the final rule, EPA has defined the maximum design through-screen velocity using 

the same concept as under Phase I and has provided additional flexibility in that the velocity can 

be measured, it can be calculated based on the design intake flow, or it can be calculated based 

on the actual monitored intake flow. In both cases, the velocity is measured at minimum ambient 

source water surface elevations. Under Phase I, however, the application of minimum ambient 

source water elevation is described differently where it is used to derive the “head loss across the 

intake screens to obtain a correlation of those values with the design intake velocity.” In this 

final rule, EPA has allowed facilities to choose a more easily employed calculation method for 

measuring the intake velocity. 

One commenter noted that lower velocities will provide insufficient warning to fish. EPA agrees 

that this may be true for velocity caps which are designed fundamentally differently than 

shoreline intakes for which the velocity compliance alternative is intended. EPA does not require 

that velocity caps that comply by meeting definition of exiting velocity caps or via the system of 

technologies compliance alternative meet the velocity compliance alternative. EPA disagrees that 

this assertion would apply to screen technology since the screen itself provides sufficient 

warning. 

Implementation

Many commenters explained that it would be difficult to measure through-screen velocity 

directly for screen technology and agreed with the suggestion in the NODA that EPA should 

allow for calculation of through-screen velocity and that the calculations should be based on 

actual flow rather than design flow since many facilities operate well below the design flow. 

EPA agrees and has included provisions in the final rule for using engineering calculations to 

determine the maximum through-screen velocity and for using either the maximum design intake 

velocity or the actual intake flow rate which requires ongoing monitoring. 

Commenters wanted EPA to let the Director set the monitoring frequency or be allowed to 

calculate the maximum expected velocity once using a reasonable worst case. EPA requires daily 

monitoring for intakes complying via the actual intake flow but notes that this monitoring in 

instances where the values are calculated should involve monitoring the flow rate, corresponding 

water depth, screens in-service, etc. Facilities complying via the maximum velocity based on the 

design intake flow will need to calculate only once based on the minimum ambient source water 

surface elevations based on BPJ. EPA concluded that it is reasonable to require those choosing to 

comply via the actual intake flow to monitor daily because (1) operating and ambient conditions 

will vary, and (2) automated means of measuring intake flows are readily available. Most 

Essay 17 151 
                                                            

facilities that completed the detailed technical survey were able to report daily minimum, 

maximum, and average intake flow volumes. 

Commenters wanted EPA to exclude intermittent or rare excursions of the 0.5 fps velocity. Some 

also suggested EPA should make exceptions for rare weather events such as drought that may 

occur for extended periods. EPA has addressed issue of intermittent or rare excursions by 

allowing the Director to authorize the owner or operator of the facility to exceed the 0.5 fps 

velocity at an intake for brief periods for the purpose of maintaining the cooling water intake 

system, such as backwashing the screen face. Also, the minimum ambient source water elevation 

for the 0.5 fps design velocity in the low velocity IM compliance alternative is to be based on 

BPJ and it is reasonable to assume that such determinations will take this into consideration. 

Regarding exceptions for longer term conditions like droughts, EPA disagrees that specific 

exceptions need to be included in the regulation. As with other situations that are truly 

exceptional, the Director can use discretion regarding the appropriate response and an upset 

provision is a common approach.16 Additionally, periodic drought conditions may be normal at 

some facilities. The velocity standard has always been intended to be “highly protective 

requirement” (see 66 FR 65302) including under conditions such as drought, where the 

biological organisms in the waterbody may be under additional stress from the low water 

conditions. Facilities where such conditions occur may need to make technology or operational 

changes in order to comply or select an alternative method of compliance. 

Commenters wanted EPA to calculate the maximum velocity based on annual average. EPA has 

decided to apply the 0.5 fps velocity as a maximum value. EPA has concluded that in order for 

the 0.5 fps velocity to be effective it must be just that, a maximum velocity. An average over any 

extended length of time would not represent a maximum value. 

Commenters wanted EPA to clarify that if the 0.5 fps velocity is met that no other IM reduction 

requirements are necessary. EPA addressed this issue in the final rule by making it clear that the 

low velocity compliance alternative is one of several IM BTA compliance options and that a 

facility only needs to select one option for each intake or the whole facility. 

Commenters were concerned that through-screen velocity cannot be physically measured and 

that through-screen velocity is subject to spatial variability. Commenters also wanted EPA to 

provide specific guidance on how to calculate through-screen velocity. Recognizing that both 

direct and indirect measurement (e.g., through head loss) can be difficult to implement, EPA has 

allowed for the maximum through-screen velocity to be measured through engineering 

calculations which are derived using physical data. EPA is aware that spatial variations of intake 

velocity can occur and has concluded that the safety factor inherent in applying the 0.5 ft/s as a 

through-screen velocity accounts for this. EPA concluded that it is not necessary to provide 

specific guidance in calculating through-screen velocity since these are standard engineering 

calculations. EPA allows the calculated velocity to be an average across the surface of the screen 

area but does not allow averaging across multiple intakes. For more discussion, see Basis for the 

Final Rule section of the preamble. 

16 See 40 FR 122.41(n). 

Essay 17 152 
Commenters wanted EPA to allow the Director flexibility in determining how facilities may 

calculate actual intake velocity based on actual flow where flow cannot be easily measured or 

where it varies with conditions such as water level. EPA agrees that there will be instances where 

the flow volume cannot be directly measured and that flow volume may, in some instances, need 

to be estimated using a reasonably reliable indirect method. The rule does not specify how flow 

is to be measured and therefore, it will be left up to the Director to determine the method to be 

used for flow volume calculation, which may include the installation of flow meters. 

Commenters are concerned that it is not always clear where to apply the 0.5 fps velocity or had 

specific suggestions regarding where it should be applied. For example, it should be applied at 

the outward-most point or first point of contact like the bar racks or barrier net. If so, then the 

entire system including all downstream technology should be deemed compliant. EPA agrees 

that it may not always be clear where the point(s) of compliance for the 0.5 fps velocity should 

be, especially if there are structures or constrictions upstream of the screens. The issue regarding 

point of compliance for the 0.5 fps in the low velocity IM compliance alternative is discussed in 

detail in Essay 14. 

Commenters argued that facilities that comply using the 0.5 ft/s velocity for a portion of time 

should get IM reduction credit. EPA intended for the 0.5 fps velocity to be protective and 

therefore it must be met under all conditions. In the final rule, facilities may obtain partial credit 

for certain technologies under the system of technologies alternative provided the facility can 

demonstrate a quantifiable reduction. For further discussion, see the preamble. 

Commenters stated that flow requirements for emergency service water systems at nuclear 

facilities should be excluded from the calculation of actual intake velocity. EPA agrees, as long 

as the emergency service water is only in operation during emergencies and periodic testing. The 

final rule specifically excludes emergency and fire suppression capacity and back-up pumps. 

This exclusion should apply to the actual intake velocity as well. See Essays 14 and 18 for more 

information. 

Commenters argued that EPA should include velocity caps and wedgewire screens as IM BTA 

compliant technologies. EPA agrees that these technologies can be very effective at reducing IM. 

EPA notes that wedgewire screens are typically designed with a through-slot velocity of 0.5 ft/s 

and that water depth above the screen does not affect the design velocity. As such, the evidence 

EPA has reviewed is convincing that most wedgewire screens will comply via the low velocity 

IM compliance alternative and do not need to be singled out as an IM compliant BTA 

technology. EPA is aware that low intake velocity is sometimes confused with velocity cap 

technologies. These concepts are not the same. For further discussion of velocity caps, see 77 FR 

34320. 

Commenters noted that low intake velocities may make some intakes more susceptible to 

colonization by zebra mussels or may result in increased siltation of the intake. EPA agrees that 

at some intakes, the site-specific conditions may result in a conflict between low intake velocities 

and certain intake design and operational considerations. Also see Essay 18. Facilities where 

such considerations may take precedence over low intake velocity are free to choose to comply 

via one of the several other IM BTA compliance alternatives that do not require low velocities. 

Essay 17 153 
Essay 17A: Closed‐Cycle Recirculating Cooling

Introduction

In the proposed rule and NODAs, as well as the Technical Development Document (TDD) for 

the proposed rule, EPA discussed a wide variety of intake technologies and operational measures 

that can be employed to reduce impingement and entrainment. This essay addresses comments 

from the public related to closed-cycle recirculating systems (CCRS), including both cooling 

towers and cooling ponds. 

To avoid confusion about the regulatory status of cooling ponds that are waters of the United 

States, the EPA uses the term impoundment when referring to cooling ponds or cooling lakes. 

In many cases, commenters advocated impoundments such as cooling ponds should be 

considered as BTA, while other comments gave reasons for rejecting CCRS including 

impoundments as the basis for BTA. Many commenters also expressed concern over a number of 

requirements, definitions, or operational measures laid out in the proposed rule, principally 

noting that these requirements were either not feasible or not necessary at most facilities. Other 

commenters suggested other technologies have performance comparable to CCRS. For 

comments concerning costs of CCRS, see Essays 21 and 55. For comments concerning cooling 

ponds and waters of the U.S., including comments on the definition of CCRS in the rule, see 

Essay 14. 

Impoundments

Comments included numerous suggestions regarding requirements for closed-cycle systems. 

Numerous comments addressed man-made cooling ponds and impoundments, including 

suggestions for exemptions and less stringent requirements for such CWIS. EPA notes that these 

suggestions assume that all cooling ponds comprise a closed-cycle system. Comments also 

addressed whether a closed-cycle system can be a water of the United States. Others argued that 

cooling ponds that were not themselves waters of the United States when they were built should 

be defined as CCRS. See Essay 14 for more details. 

Some commenters indicated that EPA should create reasonable presumptions that provide 

certainty for facilities that use cooling ponds. Some asserted that a cooling pond that functions as 

a closed-cycle recirculating system (water use reduced by 96.6 percent) should not be required to 

do more to reduce I and M since presumably any benefits do not justify the costs. Similarly 

commenters maintained that no additional controls should be required for facilities with 

constructed cooling reservoirs that use/are closed-cycle recirculating system since these are 

BTA. Commenters also asserted that EPA should exclude regulation of intakes in dedicated 

cooling ponds or allow for site-specific determination by permitting authority. Some commenters 

asserted that EPA should eliminate the entrainment requirements if a cooling pond has a 

retention time of 7 days or more. Others suggested that the regulation of intakes for makeup 

water should be left to the states that are familiar with local water issues. Finally, some asked 

whether blowdown was intended to address overfilling a pond to reduce TDS and, if not, 

suggested that EPA modify the definition to include such an operational control. 

Essay 17A 154 
A cooling pond is a man-made impoundment used either in lieu of a cooling tower or as a 

supplement to a cooling tower to remove waste heat from the plant. Once the water has cooled in 

the pond, it is reused by the plant. Some plants use cooling ponds to reduce the temperature of 

the cooling water exiting the facility before it is discharged back into a receiving waterbody. The 

pond dissipates waste heat through the surface of the pond, resulting in evaporative losses. 

Therefore, a cooling pond requires additional makeup water from another source to replace the 

water lost through evaporation. EPA’s record shows the makeup water is frequently obtained 

from a water of the U.S. (EPA’s technical survey data shows 46 power plants and 34 

manufacturers withdraw from a water of the U.S. as makeup water for a pond.) Cooling ponds 

may require a significant amount of land in order to provide a sufficient surface area for heat 

dissipation, and thus may not be feasible for other reasons. However, a cooling pond has the 

advantage of transferring a larger percentage of waste heat to the atmosphere via convection or 

slower evaporation due to lower differential temperatures, potentially reducing the rate of 

evaporation and thus the rate of consumptive water loss relative to cooling towers. 

Traditionally, a cooling lake is very similar to a cooling pond, except that the cooling lake is 

formed by impounding a water of the U.S. such as damning of a river. The EPA finds that many 

comments interchange the terms cooling pond and cooling lake, and for purposes of this essay 

EPA is not distinguishing between the two. 

The EPA is not determining which ponds are waters of the U.S. in this rule. See Essay 14 for 

more details. The definition of CCRS in the final rule includes impoundments that are not waters 

of the United States at 40 CFR 125.92(c)(1). The closed-cycle recirculating system definition at 

40 CFR 125.92(c)(2) includes a system with impoundments of waters of the U.S. where the 

impoundment was constructed prior to the effective date of the final rule and created for the 

purpose of serving as part of the cooling water system. To the extent such impoundments are 

determined not to meet the definition of a closed-cycle system, EPA notes these costs are a small 

portion of the total national rule costs because even if all ponds were determined not to meet the 

definition of CCRS, those facilities using ponds comprise approximately 2 percent of all 

facilities (less than 7 percent of the 31 percent of existing facilities that currently use CCRSs, 

noting cooling towers comprise the other remaining 24 percent). EPA conducted a more formal 

cost analysis of this at DCN 12-2502. 

Some facilities use an existing lake or reservoir as a heat sink for cooling by withdrawing the 

cooler water from the bottom of the lake, and returning the warmer water back to the source 

water. These are sometimes referred to as deep lake water cooling. EPA is clarifying that these 

systems are once-through cooling systems, and are not addressed by this essay where EPA is 

referring to cooling ponds or cooling lakes. 

The rule does not exempt man-made impoundments even if such impoundments meet the 

definition of waters of the United States. Nor does this rule alter the definition of waters of the 

United States. See the rule at 40 CFR 125.92(c) and the preamble for discussion of how 

impoundments may be demonstrated to comprise a CCRS. To the extent EPA agrees that 

artificially managed reservoirs may be different than natural lakes, EPA has discussed in the 

preamble and provided in the final rule that the Director may waive some or all of the 

information requirements of 40 CFR 122.21(r) if the intake of concern is located in a manmade 

lake or reservoir, and the fisheries are stocked and managed by a State or Federal natural 

Essay 17A 155 
                                                            

resources agency or the equivalent. Although this provision does not relieve any facility of the 

requirement to comply with the BTA standards of the rule, it does provide the Director with the 

ability in certain cases (e.g., where the biological characterization of the source water is 

significantly influenced by the actions of the natural resources agency) to reduce information 

required for the facility’s permit application. 

EPA disagrees that a cooling pond with a specified retention time should be exempt from 

entrainment requirements. The commenter did not provide any data supporting the suggestion of 

7 days retention time. EPA notes that the retention time is the volume of the aeration tank 

divided by the influent flow rate. Thus, even a 100 million gallon pond would still withdraw 14 

mgd, a volume well in excess of the rule’s applicability to those intakes designed to withdraw 2 

mgd. The rule does not categorically exclude from entrainment requirements a facility with an 

impoundment that has a retention time of 7 days or more, because the final rule requires that the 

Director address entrainment after a site-specific assessment. In this assessment, the Director 

may potentially consider retention time to the extent retention time affects adverse environmental 

impacts including entrainment. 

Commenters also expressed concern about cooling ponds or impoundments being included as 

part of the definition of a closed-cycle cooling system. EPA data show more than 50 facilities 

have cooling systems that include impoundments. In some cases, the cooling systems that 

include impoundments were created in the waters of the U.S., in whole or in part, or were created 

in uplands but withdraw makeup water from waters of the U.S. These cooling systems may 

perform like a closed-cycle recirculating system. EPA has clarified at 40 CFR 125.92(c)(2) that a 

cooling system that includes an impoundment lawfully created in the waters of the U.S for the 

purpose of cooling may be considered a closed-cycle recirculating system. As with other closedcycle recirculating systems, the Director will determine whether the impoundment minimizes the 

withdrawal of water for cooling purposes and therefore meets the definition of a closed-cycle 

recirculating system. See the preamble for discussion of this issue. 

Cooling Towers

Wet Cooling

A power plant or manufacturing facility may discharge surplus heat to the air using recirculating 

water systems which mostly use the physics of evaporation. In other words, a recirculating 

system reuses cooling water in a second cycle rather than immediately discharging it back to the 

original water source. Most commonly, wet-recirculating systems use cooling towers to expose 

water to ambient air and dissipate heat. The facility may employ either natural draft (large 

parabolic shaped towers using a chimney effect) or mechanical draft (modular towers using large 

fans). Mechanical draft towers enable a much lower profile but require more operational power 

due to the fans.17 The cooling in the tower is achieved by transferring the water’s heat to the air, 

both directly and through evaporation of some of the water. Some of the water evaporates, some 

of the water is purged to manage the accumulation of dissolved solids (called blowdown), and 

the rest of the water is sent back to the condenser in the power plant. In the United Kingdom, the 

17 EPA is aware of new designs in mechanical draft towers that use the pressurized water to operate a hydroturbine, 

thereby operating with no additional supplied electricity. As of this rule’s final issuance, the technology is patented 

and already under demonstration status at a refinery. 

Essay 17A 156 
water requirement for a 1600 MWe nuclear unit is about 2 cubic meters per second (173 ML/d), 

this being about half for evaporation and half for blow-down (see below). Chinon B in France 

(4x905 MWe) and the proposed Calvert Cliffs power plant in the U.S. (1650 MWe) use lowprofile forced-draft cooling towers. At Chinon B one cooling tower per unit is 30 m high (instead 

of 155 m required for a natural draft type there), 155 m diameter, and uses 8 MWe for its 18 fans 

(0.9 percent of power). At Calvert Cliffs the cooling tower fans will use about 20 MWe (1.2 

percent) of power. Because wet-recirculating systems based on cooling towers only withdraw 

water to replace the water that is lost through evaporation in the cooling tower, these systems 

have significantly lower water withdrawals than once-through systems, but tend to exhibit a 

higher level of water consumption. Cooling towers with recirculating water are a common visual 

feature of power plants, often seen with condensed water vapor plumes. 

The most common configuration for natural draft towers is called counterflow. These towers 

have a large concrete shell with a heat exchange “fill” in a layer above the cold air inlet at the 

base of the shell. The air warmed by the hot water rises up through the shell by convection (the 

chimney effect), creating a natural draft to provide airflow to cool the hot water which is sprayed 

in at the top. Other configurations include crossflow, where the air moves laterally through the 

water, and co-current, where the air moves in the same direction as the water droplets. These 

towers do not require fans and have low operating but significant maintenance costs. For a large 

facility they may need to be over 200 meters high. They are used most frequently in large nuclear 

and coal-fired plants in Europe, eastern U.S., Australia, and South Africa. 

Mechanical draft cooling towers have large axial flow fans in a timber and plastic structure. The 

fans provide the airflow and are able to provide lower water temperatures than natural draft 

towers, particularly on hot dry days. However, they have the disadvantage of requiring auxiliary 

power, typically about 1 to 1.2 percent of the plant’s output. Mechanical draft towers are used 

predominantly in central and western U.S. since they can provide a more controlled performance 

over a wide range of climates, ranging from freezing to hot and dry. Also they are less visually 

obtrusive designs, being less than 50 m high. For more information, see the TDD. 

Dry Cooling

Where access to water is even more restricted, or environmental and aesthetic considerations are 

prioritized, dry cooling techniques may be chosen. As the name suggests, this relies on air as the 

primary medium of heat transfer, rather than evaporation from the cooling circuit. Thus, dry 

cooling means that minimal water loss is achieved. There are two basic types of dry cooling 

techniques available. 

One design works like an automobile radiator and employs high-flow forced drafts of air past a 

system of finned tubes through which the steam passes, simply transferring heat to the ambient 

air directly. The whole power plant then uses less than 10 percent of the water required for a wetcooled plant, but 1 to 1.5 percent of power output is consumed by the large fans required. This is 

direct dry cooling, using air-cooled condenser (ACC) and it is not currently known in use for any 

nuclear power plant. 

Alternatively, there may still be a condenser cooling circuit as with wet recirculating cooling, but 

the water in it is enclosed and cooled by a flow of air past finned tubes in a cooling tower. Heat 

Essay 17A 157 
is transferred to the air, but less efficiently. This technology is not favored if wet cooling 

depending on evaporation is possible, as the energy use is only 0.5 percent of output. This 

system appears to be the back-up system planned for Loviisa in Finland in 2014. In the U.S., 

EPA is aware of several manufacturing facilities that use either or both types of dry cooling for 

specific process units. 

Hybrids

Some mechanical draft towers are a hybrid design incorporating a dry section above the wet 

section. The mode of cooling used depends on the season, with dry cooling being preferred 

during the colder months. In both dry and hybrid cases there is no dependence on vaporization 

and hence no evaporative loss of cooling water. The use of fans allows for greater control over 

cooling than relying simply on natural draft. However the heat transfer is much less efficient and 

hence requires a larger cooling plant which is mechanically more complex. 

Definition of Closed‐Cycle Recirculating Cooling

EPA found in site visits that facilities with wet cooling towers did not operate the towers to 

minimize the withdrawal of makeup water. Therefore the proposed definition of closed-cycle 

recirculating cited examples of proper operation, including flow reduction observed at power 

plants with well-operated cooling towers, as well as levels of the cycle of concentration found at 

manufacturing facilities with well-operated towers. These parameters generally represent 

minimized makeup and blowdown, with slightly different values for fresh and salt water sources 

of makeup water. In the final rule the Director will determine whether any specific 

impoundment, cooling tower, or other closed-cycle recirculating system, is properly operated and 

thus meets the requirements of the final rule. Makeup water and blowdown is specifically 

included in the definition of a closed-cycle recirculating system to reflect the efficient use of 

cooling towers as part of the recirculating cooling system. In addition, EPA notes that states 

retain the ability to address local water issues. 

Flow Reduction

Commenters provided a number of specific elements to include in the definition of a closedcycle system (e.g., considering makeup water, adjusting the flow reduction threshold, adopting 

the definition of closed-cycle cooling from the Phase I rule, establishing a “commensurate with 

closed-cycle cooling” threshold). Commenters also noted that by including the 94.9 percent and 

97.5 percent flow reduction as standards in the definition of closed-cycle, that the new unit 

requirements were more stringent than Phase I. Another commenter suggested flow reduction 

targets, such as a 90 percent reduction in water demand, as indicative of a well-operated system. 

In Phase I, EPA stated that closed-cycle cooling reduced flow by a minimum of 70 percent for 

saltwater systems. This value was adjusted in Phase II to a minimum of 72 percent flow 

reduction. Commenters then note that applying the Track II requirement for comparable 

performance of 90 percent results in a minimum flow reduction of 85 percent (because 90 

percent of the 94.9 percent flow reduction required in the proposed rule is 85 percent). The 

comments further assert that this is a change to the Phase I rule that EPA cannot lawfully make 

without giving fair notice or opportunity to comment. 

Essay 17A 158 
EPA has considered each of these suggestions, and upon review of the Phase I rule and today’s 

final rule, disagrees with these suggestions. The final rule defines the major elements of what 

constitutes a closed-cycle cooling system, and does not elaborate on narrower aspects because it 

results in a more cumbersome definition that would not improve implementation. To the extent 

that additional flexibility is necessary, the final rule provides that the Director will make the final 

determination on a site-specific basis. EPA disagrees that the proposed rule has any effect on the 

Phase I rule, and further disagrees that the definition is more stringent. First, this definition 

would not in any way change the Phase I rule, as the proposed definition of closed-cycle would 

have only applied to existing facilities. EPA also notes that the low end of the range of 70 

percent reduction cited in Phase I was given as an example of a worst-case situation where sitespecific water quality based discharge standards limit the chloride content in the blowdown to a 

maximum increase of 10 percent over background. This worst-case scenario would limit the 

cycles of concentration of the cooling tower to 1.1, a concept discussed further below. Both the 

Phase I and Phase II rulemaking records identify saltwater closed-cycle systems as clearly being 

capable of operating cooling towers at a cycle of concentration of 1.5 (or greater). This 1.5 

cycles of concentration is the level of performance equivalent to a 94.9 percent flow reduction. 

However, this specific comment is no longer relevant since in the final rule EPA has changed the 

definition of closed-cycle so that a facility does not need to demonstrate that it achieved the cited 

values for cycles of concentration and the corresponding percent reduction in flow to establish 

that it is operating a closed-cycle recirculating system. Rather, as EPA has explained in the 

preamble to the final rule, achievement of the cited values for cycles of concentration and flow 

reductions are indications of a well-operated closed-cycle cooling system. Similarly, commenters 

suggesting the standard for new units are more stringent than Phase I new facility requirements 

are incorrect. 

EPA notes that some commenters questioned EPA’s logic in stating that makeup flows at large 

closed-cycle cooling systems could approach or exceed 100 mgd. Commenters appear to have 

misunderstood EPA’s statement. EPA’s statement regarding makeup flows merely indicates the 

fact that the largest facilities with wet cooling towers still have the potential to withdraw 

significant volumes of water for cooling (77 FR 34319). With respect to the IM requirements, 

because a properly operated CCRS achieves an average flow reduction of 96 percent, such 

technologies already perform equal or better than the BTA performance standards for IM in the 

final rule. However, upon examining the data from the industry technical survey, the largest 

withdrawals for a once-through facility are approximately 3 billion gallons per day. If a facility 

of that size were to retrofit to closed-cycle cooling with a flow reduction of 94.9 percent, the 

makeup flows would be approximately 150 mgd. Thus while EPA agrees that significant 

reductions in flow over a once through cooling system is one of the best ways to minimize AEI, 

and that properly operated CCRS achieves BTA, EPA also notes that an intake flow of 150 mgd 

is not an insignificant amount of cooling water. With respect to entrainment, depending on the 

configuration (such as withdraw for makeup water is not minimized) and location of the intake 

(such as on a small river), it is possible that such an intake could still be contributing to an 

unacceptable level of adverse environmental impact, despite the magnitude of flow reduction 

already realized. 

As discussed above, if a facility’s configuration is such that it has significantly reduced its intake 

flow, but cannot demonstrate to the Director that it has a properly operated and maintained 

closed-cycle system, the facility may instead choose to comply under the “system of 

Essay 17A 159 
technologies” approach at 40 CFR 125.94(c)(7) and would use the intake flow reductions 

towards complying with the impingement mortality standards. Such a facility would also provide 

data on the reduction in flow to the Director as part of the site-specific entrainment 

determination. 

Cycles of Concentration

Some commenters appeared to misunderstand what a cycle of concentration (COC) means. 

Cycles of concentration can be measured as the ratio of chloride levels in the recirculated water 

or blowdown relative to the chloride levels in the source water, or makeup water. Cycles of 

concentration represents the accumulation of dissolved minerals in the recirculated cooling 

water. Discharge of a portion of the water (called “blowdown”) is used to control the buildup of 

these minerals. COC is a measure of how concentrated are chlorides in recirculated water 

relative to makeup water, and thus how well a system recycles intake water before replacing it 

with new withdrawals. This is not to be confused with cycles of flow, as some commenters 

appeared to do. 

Commenters questioned EPA’s definition of a closed-cycle system, including the proposed rule 

definition of proper operations based on a minimum COC for closed-cycle systems. Another 

commenter favored more stringent COC requirements. Some commenters stated that, while they 

have been operating as closed-cycle units for many years, they were concerned that their 

facilities would not be “closed-cycle recirculating systems” under the proposed definition 

because they would not achieve the required COC. EPA has found the concentration cycles in 

the majority of cooling towers usually range from 3 to 6 at power plants, and can often exceed 9 

at manufacturing facilities. However, EPA recognizes that many manufacturers have complex 

water balances, and calculating a specific flow reduction attributable to cooling water use could 

be difficult and time consuming. In such cases, many manufacturers could far more readily 

calculate the cycles of concentration of particular unit operations, and could therefore show those 

unit operations that use cooling water meet the conditions for closed-cycle cooling. EPA found 

in site visits many complex manufacturing plants already have this capability, and have achieved 

very high COC. Likewise, power plants may find it much easier to measure flow than cycles of 

concentration. Accordingly, EPA’s proposed rule attempted to recognize performance using 

either metric. EPA expects most power generators would use percentage flow reduction to 

demonstrate they are closed-cycle, and expects most manufacturing facilities would use COC for 

those units that utilize water for cooling purposes. Increasing the amount of minerals present in 

the water by cycling can make water less aggressive to piping; however, EPA is also aware that 

excessive levels of minerals (such as found in certain source waters, most notably those with 

higher salinity) can cause scaling problems, leading to different levels of both metrics for 

freshwater and saltwater facilities. After EPA carefully considered these issues, EPA concluded 

that the most important aspect of the definition of a properly operated closed-cycle cooling 

system is that the makeup flow be minimized. Thus EPA has removed the numeric levels of the 

metrics as threshold, while retaining the minimized makeup flow aspect of the definition. 

While EPA has determined that a COC of 3.0 for freshwater facilities and 1.5 for marine 

facilities (approximately equivalent to a percent reduction in flow of 97.5 percent and 94.9 

percent, respectively) is indicative of a well-operated cooling system (i.e., one that truly 

minimizes makeup withdrawals), as discussed above the EPA has decided not to include a 

Essay 17A 160 
minimum COC requirement as part of the definition for closed-cycle systems. Instead, the 

definition at 40 CFR 125.92 requires makeup flows be minimized. These flow reductions and 

COC serve as indicators of minimized makeup flows, and thus may be used by Directors when 

assessing performance of a particular CCRS. Regardless of whether facilities achieve either these 

levels of COC or reductions in flow, the Director would determine whether such facilities in fact 

are operating as a close-cycle recirculating cooling system. The Director would review the 

information provided by the facility and determine if the facility’s configuration and operation 

are otherwise consistent with the definition of a closed-cycle cooling system in the final rule. A 

facility may, during the permitting process, demonstrate how particular site-specific 

circumstances may affect the performance of its closed-cycle system relative to the benchmarks 

EPA has suggested for evaluating whether a system is a closed-cycle recirculating system. 

Therefore EPA notes that these metrics, while not an explicit requirement in the final rule, are 

applicable in many instances, and therefore as stated in the preamble these metrics are provided 

as examples. A facility with CCRS systems but that do not meet the definition of closed-cycle 

cooling will need to demonstrate to the Director the additional technologies or operational 

measures employed are adequate to achieve BTA under one of the other compliance alternatives. 

As an example, in the case of a facility that uses makeup water from a freshwater source, a 

Director may determine that a closed-cycle recirculating system can generally be deemed to 

minimize makeup and blowdown flows if it reduces actual intake flows (AIF) by 97.5 percent as 

compared to a once-through cooling system or if its cooling tower is operated at a minimum 

cycles of concentration of 3.0. And likewise, in the case of a facility that uses makeup water 

from a saltwater, brackish, or other source with a salinity of greater than 0.5 parts per thousand, a 

Director may determine that a closed-cycle recirculating system can generally be deemed to 

minimize makeup and blowdown flows if it reduces AIF by 94.9 percent as compared to a oncethrough cooling system or if its cooling tower is operated at a minimum cycles of concentration 

of 1.5. These reductions and cycles of concentration are illustrative. A Director may determine 

that other levels near these numbers could also constitute a closed-cycle system. The final rule 

further recognizes that in certain unavoidable circumstances, these levels for COC or percent 

flow reduction might not be achievable at all facilities. Such circumstances could include 

situations where water quality-based discharge limits might limit the concentration of a pollutant 

that is not readily treatable in the cooling tower blowdown or situations where varying source 

water quality could lead to unavoidable problems concerning scale formation, solids buildup, 

corrosion, or media fouling. Such facilities should demonstrate these circumstances to their 

Director and indicate the measures they have taken to minimize makeup flows. The Director will 

retain the discretion to conclude that the particular facility employs a closed-cycle recirculating 

system when the benchmarks are not met. 

EPA disagrees with the commenter in favor of increasing the COC requirement, as such a 

requirement could increase chemical costs and water treatment costs, not reduce them (as stated 

by the commenter). The reference cited in the comment was developed for small cooling systems 

that discharge to a wastewater treatment plant with a stated goal of reducing its discharge flow, 

which ultimately affects the strategies that the treatment plant may promote to its clients. While 

EPA recognizes that a reduction in total flow (achieved by increasing the COC) may reduce 

certain chemical costs on a simple mass basis, the increased COC can introduce or exacerbate 

other issues (such as scale and chemical deposits) that would then need to be addressed by other 

chemicals. As the cited reference noted, “[d]etermining the optimum number of cycles of 

Essay 17A 161 
concentration is a balancing act between the reduced chemical, water, and sewage costs at higher 

cycles of concentration versus the increased risk of scale formation.” In the final rule, EPA has 

not included a requirement for COC in the definition of closed-cycle. 

Intermittent Flow

Comments addressed the intermittent flow provision in the definition of closed-cycle 

recirculating system. Some commenters asserted that a prohibition against any level of 

continuous flow is unreasonable. Commenters argued that there is no reason why a closed-cycle 

recirculating system has to have an intermittent flow of makeup water, but there are reasons why 

a consistent flow may be desirable. Commenters argued that some ponds withdraw a continuous 

flow because this protects the source waterbody. Commenters noted that limiting makeup water 

to replenishment of certain losses will interfere with common power plant practices. 

The commenter appears to misunderstand the rule definition. The definition of closed-cycle 

recirculating system does not require an intermittent flow in the final rule. In addition, the final 

definition provides flexibility so that replenishment can extend to losses beyond blowdown, drift 

or evaporation in specified circumstances. Such replenishment is not prohibited by the final rule. 

Under the final rule, in evaluating whether a particular cooling water intake structure represents a 

CCRS, the Director will determine whether such withdraws are for cooling purposes and thus are 

attributable to a determination that the withdrawals constitute minimized makeup. 

Emergency Flows

Some commenters sought clarity on the 316(b) rule applicability to emergency flows. In cases 

where the Director will make a determination as to whether the facility’s cooling system meets 

the definition of a closed-cycle system, EPA’s intent is that the withdrawal of small amounts of 

service water (for uses such as fire suppression, potable water, screenwash water, vehicle wash 

water, and such) do not preclude consideration of the system as closed-cycle. EPA has clarified 

in the definitions of the final rule that design intake flow does not include emergency and fire 

suppression capacity. 

Performance of CCRS

EPA has made it clear that a facility that uses a closed-cycle recirculating system, as defined in 

the rule, would meet the rule requirements for impingement mortality at 40 CFR 125.94(c)(1). 

As discussed above, EPA has made this decision based upon the record that shows that CCRS on 

average reduces flow by 96 percent, and therefore properly operated CCRS meets or exceeds the 

BTA performance standard for IM. The final rule language specifically identifies closed-cycle as 

a compliance alternative for the IM standards. 

Demonstration Status

Several commenters suggest that CCRS is not demonstrated. EPA disagrees. Cooling towers are 

used by power generators of all fuel types, using both fresh water and salt water as the source 

makeup water. See EIA Form EIA-860 (2012). Similarly, manufacturers use both wet and dry 

cooling where cooling water is used for power generation. Further, EPA has identified numerous 

manufacturers that use CCRS for cooling of process units at iron and steel plants, petroleum 

Essay 17A 162 
refineries, chemicals manufacturers, and food and agricultural products; see the site visit reports 

in the record. According to U.S. Energy Information Administration, Form EIA-860, Annual 

Electric Generator Report of the 1,655 operable cooling systems in the United States, 875 (53 

percent) reuse water either through a cooling tower or a cooling pond, 719 (43 percent) do not 

reuse water, and 61 are either dry or hybrid (switching between dry and wet cooling depending 

on the temperature and availability of water). See the TDD for more information. 

Comparison to Other Technologies

Commenters requested EPA consider technologies that perform comparably to CCRS. Most 

commenters did not suggest what technologies demonstrated a performance comparable to 

CCRS. None of the commenters provided performance data that demonstrated performance 

comparable to CCRS. One commenter specifically argued that wedgewire screens can offer 

comparable performance to closed-cycle cooling. The commenter did not provide comparability 

performance data. 

EPA disagrees with all of these comments. With respect to traveling screens, the record clearly 

shows that the performance of traveling screens does not equal or exceed the performance of 

CCRS for impingement mortality, and moreover traveling screens offer no reduction in 

entrainment unless the screens consist of fine mesh. While some sites obtained reductions in 

entrainment with one or more technologies including fine mesh screens, EPA found that some 

studies did not distinguish between intake location (such as offshore submerged intakes) and the 

fine mesh screens themselves. Other studies showed a bias towards older/larger larvae, which are 

generally more developed and starting to exhibit survival traits and avoidance responses. Studies 

also did not fully characterize survival of entrainable organisms. For all of these reasons, fine 

mesh screens do not offer survival of entrainable organisms to the extent CCRS can. The record 

shows that CCRS reduces the entrainment mortality of eggs and larvae 8-fold more than fine 

mesh screens (based on the mean value of performance data for both eggs and larvae); see TDD 

Chapter 6 for more details. EPA further notes that even if fine mesh performance was 

comparable to CCRS, fine mesh is not available at an estimated 17 to 55 percent of facilities 

based on the need to expand the existing intake to accommodate fine mesh (specifically 

reflecting analysis of existing intakes to be enlarged to accommodate fine mesh with 2.0-mm and 

0.5-mm mesh, respectively). EPA’s technical analysis shows as many as 68 percent of facilities 

would need to expand the size of their intake by more than five times, leading EPA to conclude 

that fine mesh screens would not be an available technology at those sites. As noted above, EPA 

did not receive any comments or data to the contrary. See Section VI.C of the preamble for 

further discussion of fine mesh screens. EPA notes that high sediment waterbodies pose a 

challenge for fine mesh screens, and high sediment water can cause “blinding” of the intake. 

Evaporative Losses

Commenters expressed concern about consumptive losses of water due to a conversion to a 

closed-cycle cooling system. Riverkeeper noted that consumption of water should be a factor 

considered in evaluating cooling system options. EPA disagrees that this is a significant concern. 

EPA has considered this issue in several ways. First, EPA found that comparisons of oncethrough to cooling towers provided in comments ignored the additional evaporation of water 

from the downstream discharge of heated water from a once-through cooling system. The 

Essay 17A 163 
discharged water from once-through cooling may exceed 100 degrees. The elevated source 

waterbody temperature has increased evaporation than would occur in the absence of the thermal 

discharge. Second, in most cases, there are multiple facilities that withdraw from the same source 

water, resulting in cumulative impacts such as progressively higher source water temperatures. 

See Essay 14 for more discussion of the frequency of cumulative impacts. Third, evaporation 

modeling shows in certain cases, such as where the source of cooling tower makeup water is a 

small river or lake, the additional evaporative loss in the source water due to the discharge of 

heated water from a once through system is comparable to the evaporative losses from a cooling 

tower. In contrast, the heated water from a cooling tower may not significantly contribute to 

evaporation from an ocean, nor does an ocean intake likely contribute to significant evaporative 

losses due to cooling towers. Fourth, a source water that is supposedly too small to support a 

cooling tower (due to evaporative losses) is also too small a source of water to provide adequate 

flow for a once-through cooling system. This has prompted some facilities to retrofit oncethrough cooling to cooling towers; see, e.g., DCN 10-6524, 10-6536 and 10-6538. For all of 

these reasons, EPA’s record does not support the position of commenters that increased 

evaporative losses from a closed-cycle system should be a factor in EPA’s consideration of 

closed-cycle for national BTA requirements. Evaporative loss of water, however, is one of a 

number of factors that the Director may consider in determining BTA requirements for 

entrainment on a site-specific basis. EPA agrees that in certain watersheds where available 

source water is a significant concern (e.g., arid areas), evaporative consumption may play a 

larger role in decision-making regarding cooling water intake system choices. Therefore the final 

rule requires a facility to evaluate evaporative losses on a site-specific basis when submitting the 

Non-Water Quality Environmental and Other Impacts Assessment information required in 40 

CFR 122.21(r)(12). 

EPA agrees that cooling towers give rise to some level of water consumption, with data in EPA’s 

record showing up to 3.0 liters being evaporated for each kilowatt-hour produced, depending on 

conditions. See the TDD for more details. This evaporative water loss by phase change of a few 

percent of it from liquid to vapor is responsible for removing most of the heat from the coolant 

water. Water evaporating from the cooling tower leads to an increasing concentration of 

impurities in the remaining coolant. Some bleed – known as “blowdown” – is needed to maintain 

water quality. Despite many coal and nuclear plants using wet cooling towers, in the U.S. electric 

power generation accounts for only about 3 percent of all freshwater consumption, according to 

the U.S. Geological Survey - some 15.2 gigaliters per day (5550 GL/yr). However, as mentioned 

above comparisons made by commenters neglect evaporation of once-through cooling systems. 

Commenters provided an August 2010 report from DOE’s National Energy Technology 

Laboratory (NETL) which analyzed the implications of new environmental regulations for coalfired plants in the U.S. The NETL report noted that the projected increase in coal-plant water use 

over the next two decades if direct cooling is no longer allowed on new plants does not factor in 

the likelihood that many coal plants will add carbon capture and storage (CCS) technology to 

constrain U.S. carbon emissions, thereby increasing water consumption by a further 30-40 

percent. EPA disagrees that such water consumption is a result of this rule. 

Essay 17A 164 
Alternative Sources of MakeUp Water

Commenters observed that the definition of CCRS should allow for other uses of makeup water 

beyond “blowdown, drift and evaporation”, such as water stored in cooling ponds. In addition, it 

should clearly allow other uses, including service water, emergency back-up and fire protection, 

and facility maintenance and sanitary uses (also screen washing, air preheater washing, boiler 

makeup, and wetlands rehydration). 

EPA acknowledges water may be used for purposes other than for cooling, and distinguishes 

between makeup water for cooling and water used for other purposes. The final rule definition 

requires makeup be minimized and provides for the replacement of water lost due to evaporation. 

The final rule also allows for such systems to replace other water losses. See the final definition 

of CCRS at 40 CFR 125.92. See Essay 14 for more details. 

Rejection of CCRS as BTA

As explained in the preamble, closed-cycle cooling based on wet cooling towers is a highly 

effective technology for reducing both impingement and entrainment. However, with respect to 

entrainment, the EPA has concluded that it should not adopt a BTA entrainment standard 

prescribing a uniform national technology with a requirement for a (CCRS) closed-cycle 

recirculating system based on wet cooling towers. EPA concluded that closed-cycle cooling is 

not an available entrainment reduction technology on a national scale and therefore should not 

form the basis for the “best technology available” entrainment standard. 

Three Factors

EPA concluded that closed-cycle cooling is not an available entrainment reduction technology on 

a national scale and therefore should not form the basis for the “best technology available” 

entrainment standard. The record shows that closed-cycle cooling is not technically available in a 

number of circumstances either because (1) land availability and geographical constraints could 

be a factor on a local basis (such as limited space available to install cooling towers, noise 

mitigation, and setback distances for plume abatement); (2) increased air emissions (such as due 

to the need for increased fuel burned to operate the cooling towers); and (3) remaining useful 

plant life (for example a plant scheduled to be shutdown in 3 years will result in very little 

entrainment reductions as compared to a facility that will continue to operate for a significantly 

longer period). That is, the record demonstrates that while EPA cannot identify with precision 

the extent of these limitations on installing closed-cycle cooling systems nationwide, the record 

indicates that the circumstances are neither isolated nor insignificant. EPA tried to identify 

characteristics for which it has information that would allow it to subcategorize those facilities 

where closed-cycle is not available (e.g., land size threshold), but was unable to do so and 

concluded that such determinations can only be made on a site-specific basis consideration; see 

the TDD for further discussion. Furthermore, contrary to the statement made by some 

commenters, EPA reasonably concludes that the availability of a technology to the industry is an 

appropriate factor for evaluating BTA technology bases for national standards. EPA has 

historically evaluated the availability of a technology to the industry in making technology base 

determinations for other national technology based performance standards. Examples of nonwater quality and other impacts considered in this rule at 40 CFR 122.21(r)(12) include changes 

to energy consumption, estimates of air pollutant emissions, changes in noise, impacts to safety, 

Essay 17A 165 
facility reliability, and consumption of water. For more information on the reasons EPA rejected 

closed-cycle cooling as the basis for national BTA entrainment requirements, see the preamble. 

Cost and Affordability

Commenters suggested that CCRS was too expensive. Some commenters provided facility 

estimates and EPA considered these data; see DCNs 12-6655 and 12-6656. Other commenters 

cited energy costs and lowered plant efficiency. For example, cooling towers with recirculating 

water reduce the overall efficiency of a power plant by 2-5 percent compared with once-through 

use of water from sea, lake or large stream, the amount depending on local conditions. 

Commenters cite a 2009 U.S. DOE study which says they are about 40 percent more expensive 

than a direct, once-through cooling system. Elsewhere the study says dry towers are three to four 

times more expensive than a recirculating wet cooling system. 

As discussed above, EPA did not conclude that closed-cycle cooling is not available at every 

facility. Nor has EPA rejected CCRS on grounds that the technology is not economically 

achievable. While EPA did consider costs, costs were not a dispositive factor in the decision to 

reject CCRS based on cooling towers. Rather, EPA considered its applicability to the industry as 

a whole. See the EA for the impacts analysis of regulatory options based on CCRS as BTA. 

Other Options Considered Based on CCRS

EPA also examined other closed-cycle cooling scenarios in developing the final rule. Some 

commenters (including Riverkeeper) advocated that EPA consider dry cooling in determining 

national BTA. For dry cooling, consistent with EPA’s previous findings (see, e.g., 69 FR 41608), 

EPA found that it does offer a slightly greater flow reduction (essentially 100 percent reduction 

in intake withdrawals) but at a significantly higher cost. Thus, dry cooling would reduce IM&E 

by roughly 5 percent over wet cooling. In Phase II and Phase III, EPA found that dry cooling 

costs as much as 10 times as wet cooling. While dry cooling may not be as costly today, it still 

costs at least twice as much as wet cooling. Furthermore, dry cooling has a higher energy penalty 

than wet cooling. While EPA recognizes that dry cooling is becoming a more common 

technology and that its costs have decreased over the past decade, EPA ultimately rejected this 

option for the same reasons that it rejected all other closed-cycle options: (1) land availability 

and geographical constraints could be a factor on a local basis (such as limited space available to 

install cooling towers, noise mitigation, and setback distances; (2) increased air emissions (such 

as due to the need for increased fuel burned to operate the cooling towers); and (3) remaining 

useful plant life (for example a plant scheduled to be shutdown in 3 years will result in very little 

entrainment reductions as compared to a facility that will continue to operate for a significantly 

longer period). Refer to the proposed rule preamble (76 FR 22208) and the TDD for more 

information on this option and today’s preamble for information on why closed-cycle cooling 

was not selected as BTA for entrainment at existing facilities. For all of these reasons, EPA has 

concluded that dry cooling is not available. Further dry cooling is not a cost-effective option (5 

percent improved performance over wet cooling at anywhere from 2 to 4 times the cost) for the 

reduction of impingement under a national regulation for existing facilities. See 67 Fed Reg. 

Essay 17A 166 
                                                            

 

17122, 17168 (2002).18 Dry cooling may still be considered by the Director as part of the 

entrainment determination, and may for example, be justified over wet cooling in those 

geographic areas with insufficient water resources to support any water withdraws for cooling, or 

where cooling tower drift has been confirmed as a concern in an area where entrainment poses an 

AEI. 

EPA solicited comment in the proposed rule on the use of seasonal operation of closed-cycle 

cooling during peak entrainment season. Commenters noted that, at some sites, this may yield 

equivalent reductions in impingement and entrainment to a fully closed-cycle system, while 

reducing the overall energy penalty and O&M costs. Other commenters noted that closed-cycle 

cooling should be utilized year-round, and that additional fish-protective measures (such as 

seasonal outages) should be utilized during peak entrainment season. EPA appreciates the 

submittal of technical studies on seasonal closed-cycle systems that are included in the record for 

today’s final rulemaking. EPA generally agrees that the long-term costs of a seasonal closedcycle cooling option would likely be lower than a fully closed-cycle option, due to reductions in 

O&M over the life of the technology. But EPA ultimately rejects this option due to the same 

factors EPA did not select other options based on closed-cycle as BTA; refer to the proposed rule 

preamble (76 FR 22208) for more information on this option and today’s preamble for 

information on why closed-cycle cooling was not selected as BTA for entrainment. 

Some commenters suggested different applicability thresholds for the final rule requirements. 

Such thresholds do not change EPA’s three primary reasons for rejecting CCRS as BTA. Also 

see Essay 14 regarding scope and applicability. 

See Essay 19 regarding EPA’s consideration of a requirement for CCRS with an off-ramp, or 

consideration of a final rule option that would require CCRS with a rebuttable presumption of 

CCRS as BTA. 

18 EPA encourages permitting authorities to consider utilizing the technology on a site-specific basis where 

appropriate, as it would meet the definition of a closed-cycle cooling system at 40 CFR 125.92. However, dry 

cooling is not required under the rule and existing facilities are not required to retrofit to dry cooling under the rule. 

EPA also encourages the use of dry cooling technologies, especially for cooling smaller process units at 

manufacturing facilities. Facilities may demonstrate reductions in cooling water intake flows due to the use of dry 

cooling through 126.94(c)(6) system of technologies. 

Essay 17A 167 
Essay 18: Impingement and Entrainment Technologies and Operational

Measures

Introduction

In the proposed rule and NODAs, as well as the Technical Development Document (TDD) for 

the proposed rule, EPA discussed a wide variety of intake technologies and operational measures 

that can be employed to reduce impingement and entrainment. This essay addresses comments 

from the public related to these technologies and operational measures. In many cases, 

commenters advocated that a given technology or operational measure should be considered as 

BTA (or as credit towards meeting BTA) in the final rule. Many commenters also expressed 

concern over a number of requirements laid out in the proposed rule, principally noting that these 

requirements were not feasible or necessary at most facilities. 

EPA’s record demonstrates that a wide variety of technologies can be used by themselves or in 

combination as part of a “system” of technologies to minimize impingement and impingement 

mortality. The record shows the same is not true about entrainment controls. Commenters 

provided information on the performance of some technologies, as well as opinions on how EPA 

should incorporate the performance of some technologies or operational measures in the final 

rule framework. The final rule addresses impingement by establishing a national impingement 

mortality standard with seven different compliance alternatives whose performance is 

comparable to or better than that of the technology – modified traveling screens with fishfriendly returns – that EPA determined is the best technology available for minimizing 

impingement. The final rule establishes a national BTA standard for entrainment that requires 

determination of entrainment controls on a site-specific basis in a structured proceeding requiring 

consideration of prescribed factors. See the preamble sections V and VI for a description of the 

final rule. 

Background

Over the course of the 316(b) rulemaking process, beginning with the development of an 

industry- wide technical survey conducted in 2000, EPA has collected a wealth of knowledge 

about intake technologies, their feasibility, costs, and performance. Part of this improved 

understanding is a result of EPA’s clear articulation of impingement versus impingement 

mortality, and entrainment versus entrainment survival. Further, entrainment exclusion does not 

necessary equate to entrainment survival (76 FR 22185). EPA has found that entrainable 

organisms that are collected show poor survival in the case of most eggs, and essentially no 

survival of larvae. Consequently, on the basis of the record information it has reviewed, EPA 

concluded for purposes of this rule that all entrained organisms die, i.e., no entrained organisms 

survive. (See, for example, 76 FR 22188 (April 20, 2011) and 69 FR 41620 (July 9, 2004).) See 

the proposal preamble at 76 FR 22197 as well as additional discussion in the preamble for the 

final rule for a complete discussion of this issue. Additional perspective was obtained through 22 

site visits during the Phase II rule development and over 50 site visits to both electric generators 

and manufacturers since 2007; see TDD Chapter 2 for more details. EPA also collected 

information from facilities the staff did not physically visit, and several stakeholders provided 

Essay 18 168 
information to EPA in addition to that submitted during the public comment period. In some 

cases technologies have improved (such as composite materials that are lighter, sturdier, and less 

expensive), new technologies have been developed (such as new rotary screens), or the data 

identifying the performance of a given technology has been refined (such as lab studies to 

measure conditions before and after an intake technology where in-situ monitoring is not 

practical). Accordingly, during each phase of the 316(b) rules development, EPA has provided 

extensive discussions reflecting the most current understanding of the variety of intake 

technologies and operational measures: 

Phase I: The proposed rule TDD (Economic and Engineering Analyses of the Proposed §316(b) 

New Facility Rule, August 2000) analyzed several compliance alternatives, including relocating 

an intake, reducing intake flow (including conversion to closed-cycle cooling), reducing intake 

velocity, and installing a variety of intake technologies (traveling screens with fish baskets, 

wedgewire screens, and velocity caps). The final rule TDD (Phase I—New Facilities, Technical 

Development Document for the Final Regulations Addressing Cooling Water Intake Structures 

for New Facilities, November 2001) dedicated an entire chapter to discussing the efficacy of 

intake technologies, including many that were not addressed in the proposed rule analysis. This 

discussion also included EPA’s first attempt to quantitatively describe the percent reduction in 

impingement (not impingement mortality) and entrainment (see Table 5-1), as well as providing 

a fact sheet for each technology that provided technology performance data, site-specific details 

from individual facilities, design criteria, and advantages and disadvantages of each technology. 

Phase II: EPA expanded its data collection efforts for information on intake technologies, 

especially with regards to performance data. As described in the NODA (68 FR 13538, March 

2003) and TDD for the final rule (Phase II—Large existing electric generating plants, Technical 

Development Document for the Final Section 316(b) Phase II Existing Facilities Rule, February 

2004), EPA developed a technology efficacy database to support the development of a 

performance range that facilities would be required to meet. EPA also hosted the Symposium on 

Cooling Water Intake Technologies to Protect Aquatic Organisms in May 2003 to gather experts 

in the field of intake technologies. 

Phase III: In the proposed TDD (Technical Development Document for the Proposed section 

316(b) Phase III Rule, November 2004), EPA added information regarding technologies for 

intakes at offshore facilities. 

Existing Facility Rule: As described in the proposed rule (76 FR 22184, April 20, 2011), NODA 

(77 FR 34317, June 11, 2012), and proposed TDD (Technical Development Document for the 

Proposed Section 316(b) Phase II Existing Facilities Rule, March 2011), EPA expanded its data 

collection efforts for intake technology data. Specifically, EPA collected and reviewed a large 

number of documents in the development of the impingement mortality performance standard. In 

doing so, EPA conducted a detailed evaluation of the intake technologies used at facilities 

documented in impingement studies and retained only those that met certain criteria for 

acceptability for developing the performance standard. (See Essay 16A and Chapter 11 of the 

TDD for more information on the development of the standard.) EPA also developed more 

detailed analyses about individual technologies or operational measures as needed and included 

these materials in the record; for example, see DCN 10-6601 for a memo on variable speed 

pumps. 

Essay 18 169 
Overall Response: Introduction

As discussed above, EPA has collected and evaluated data on the performance of intake 

technologies and operational measures over considerable time and with numerous opportunities 

for public input. In the Phase II final rule, EPA stated that “[while] many documents do show a 

level of success in reducing impingement mortality or entrainment, other studies have shown the 

deployed technology to be unsuccessful or at best inconclusive. EPA does not view the varying 

degrees of success with regards to a specific technology as indicative that the performance 

standards cannot be met, but rather as evidence that some technologies work in some 

applications but not in others.” (See 69 FR 41612, describing the data used to develop the nowwithdrawn performance range.) Since the Phase II rule, EPA has identified additional studies and 

data showing the performance of the technologies considered for the final rule. This information 

has resulted in an improved understanding of the relationship between impingement and 

impingement mortality, entrainment and entrainment mortality, entrainment survival, and 

impinged entrainables (or “converts”). See VI.B of the preamble and Essay 15 for detailed 

discussion of these concepts. 

Impingement Mortality BTA Standard

As discussed in the preamble, closed-cycle cooling is the most effective technology for reducing 

both impingement mortality and entrainment. EPA, however, decided that it should not base the 

BTA standards for IM and entrainment on the performance of closed-cycle cooling systems 

based on a number of factors (including that CCRS is not available nationally). See preamble 

section VI and Essay 15 for further explanation of the reasons for EPA’s decision. 

In addition to closed-cycle cooling, EPA has identified several other technologies that are also 

effective in reducing impingement and impingement mortality. The costs, availability, feasibility, 

and performance of these technologies are discussed in TDD Chapter 8. However, other than 

modified traveling screens with fish returns, none of these technologies are available nationally. 

As stated in the preamble, as a result of this thorough evaluation, EPA decided to base the BTA 

standard for impingement mortality on the performance of well-operated modified traveling 

screens with a fish handling and return system. EPA has defined “modified traveling screens” at 

§ 125.92 to include, among others, modified Ristroph screens with a fish handling and return 

system, dual flow screens with smooth mesh, and rotary screens with fish returns such as 

vacuum pumps. The definition derives from, and reflects, the technologies EPA used to calculate 

the impingement mortality reduction performance standard. The definition reflects the common 

features of the most effective screens it used in its assessment of the IM performance standard. 

EPA often refers to this IM BTA technology simply as traveling screens or modified traveling 

screens throughout this essay. 

As discussed in the proposed existing facility rule (76 FR 22202), EPA developed a monthly and 

annual performance standard for impingement mortality based on the performance of modified 

Ristroph traveling screens. EPA revised this standard since proposal, as noted in the 

impingement mortality discussion in a 2011 NODA (77 FR 34317) and described in the 

preamble for today’s final rule, in part due to data received from commenters and in part due to 

additional analyses performed by EPA. Nonetheless, it is apparent that modified traveling 

screens are a widely available, feasible, cost-effective, and high performing technology for 

Essay 18 170 
                                                            

 

 

reducing impingement mortality. See TDD Chapter 4 for more information on the large number 

of facilities utilizing traveling screens. 

This does not mean that facilities must install traveling screens with fish handling and return 

systems. Rather, as mentioned above, EPA recognizes other technologies (that may not be 

available nationally), are at least as effective as the BTA IM technology basis. As such, the rule 

identifies four other technologies that will also comply with the BTA impingement mortality 

standard (closed-cycle recirculating systems19, reduced design intake velocity, reduced actual 

intake velocity, and existing offshore velocity caps). The data in the record demonstrate that 

these technologies will achieve impingement mortality reduction as good as or better than welloperated traveling screens and therefore comply with the BTA impingement mortality standard 

of today’s final rule. In addition, EPA has included a flexible approach that allows facilities to 

comply by employing any of seven alternatives for achieving the BTA impingement mortality 

standard, including monitored compliance with a numeric impingement mortality performance 

standard. See Essay 16 for more detailed discussion. 

Many commenters provided information on additional technologies and operational measures. 

EPA appreciates the additional data, and upon thorough review has concluded that none of these 

may be selected as the basis for BTA for impingement mortality or included as a compliance 

alternative in the final rule.20 However, as discussed in the preamble, facilities may choose the 

technologies provided they demonstrate the impingement mortality performance standard has 

been met. Also see § 125.94(c)(7). 

Entrainment BTA Standard

EPA has identified several technologies that reduce entrainment, but the performance of these 

technologies does not approach that of closed-cycle. EPA has found generally low performance 

for entrainment by these technologies, and finds greater uncertainty in their performance 

compared to IM technologies. Furthermore, some of these entrainment technologies have 

specific limitations (e.g., site location) that restrict their availability and feasibility, thus 

precluding their use as BTA technology at many locations. For all of these reasons, EPA did not 

select any one of these technologies as the basis for the BTA standard for entrainment. Instead, 

the national BTA entrainment standard for existing facilities requires the establishment of BTA 

entrainment control measures on a site-specific basis in a prescribed permitting setting. See 

preamble Section VI and Essay 15 for more information. 

Specific Technologies Discussions

Below, EPA addresses each of the specific technologies discussed in the comments; these 

technologies can generally be divided into three categories: flow reduction, exclusion and 

19 EPA does not intend for facilities to install closed-cycle cooling solely for the purpose of meeting the IM 

requirements. In fact, EPA expects all facilities could comply with IM requirements without relying on closed-cycle 

cooling (see Exhibit VIII-1).

20 This essay generally focuses on the application of technologies to reduce impingement mortality. Each technology 

discussed below may be appropriate, however, for consideration in addressing site-specific entrainment 

requirements. 

Essay 18 171 
                                                            

collection technologies, and avoidance/behavioral technologies.21 For purposes of this 

discussion, low intake velocity which allows fish and shellfish to escape impingement is 

considered an avoidance/behavioral technology; see Essay 17 for more information specific to 

this technology. Similarly, see detailed discussion of CCRS and cooling towers are found in 

Essay 17A. 

Flow Reduction Technologies

Several technologies are available that employ flow reduction, including wet-cooling towers, that 

are effective for reducing impingement mortality, entrainment or both. Some commenters 

(including Riverkeeper) requested that EPA use closed-cycle cooling based on wet cooling 

towers as the technology basis for performance requirements for impingement mortality and 

entrainment in the final rule. EPA disagrees; as described in the preamble, Essay 15, and other 

essays, EPA is not requiring closed-cycle cooling or equivalent performance for either 

impingement mortality or entrainment for existing facilities in this rule. However, flow reduction 

such as that obtained via cooling towers and similar closed-cycle recirculating systems remain 

the most effective technology in reducing flow and associated impingement mortality and 

entrainment, providing an average 96 percent reduction in mortality. See Essay 17A. If a facility 

reduces intake flows, it similarly reduces the number of organisms subject to impingement and 

entrainment. 

Riverkeeper advocated requiring additional technologies to be installed on intakes that supply 

makeup water to a closed-cycle cooling system. EPA disagrees that additional technologies are 

necessary for IM, as properly operated cooling towers already achieve an average 96 percent 

reduction in IM. Therefore EPA has clarified in the final rule that properly operated CCRS 

including wet cooling towers are “pre-approved” technologies for IM at § 125.94(c)(1). Also, see 

Essays 10 and 16. 

EPA also received comments on other methods of flow reductions. In general, EPA agrees that 

these technologies may be viable for reducing flow on a site-specific basis, but ultimately 

concluded that these technologies are not feasible at all locations, the performance of these 

technologies is too low to represent BTA, and therefore these technologies are not appropriate 

for setting the national BTA for impingement mortality and/or entrainment. 

	 Variable speed pumps (VSP) or variable frequency drives (VFD): VSPs can typically 

reduce intake flows by approximately 8-15 percent, but are not widely used, based on 

data and information in the record. The reduction in flow is dependent on how often the 

facility can utilize the variable speed drives on the pumps, which is generally a function 

of generating needs and the temperature of the source waterbody. As noted by 

Riverkeeper, these reductions in flow may be somewhat uncertain, as they may be 

realized only during certain periods of time depending on operational considerations, but 

over the course of long-term use significant reductions in flow may be obtained. In 

particular, baseload power generating facilities have a more consistent waste heat load, 

and are the least likely to reduce overall cooling water flows except when the source 

21 For a detailed technical discussion of each of these technologies, please refer to the TDD; the information below 

provides EPA’s response to commenter’s suggestions regarding the use of these technologies. 

Essay 18 172 
cooling waterbody is significantly colder. Given the relatively low volume of annual 

intake flow reduction (at the most 15 percent for load following plants, and closer to zero 

for base load facilities), EPA did not consider VSPs as a nationally available technology 

for reducing impingement mortality. VSP are unlikely to reduce intake flows 

significantly at manufacturing facilities, because most manufacturers are operating almost 

continuously. Nonetheless, a facility that uses VSP may obtain credit for such flow 

reductions. A facility would do this by demonstrating the flow reductions obtained by the 

use of a VSP and then applying this credit towards part or all of its total required IM 

reduction under the “system of technologies” approach at § 125.94(c)(6). One commenter 

noted that such reductions must be reflective of actual operating conditions. EPA agrees 

and the final rule requires two years of flow data to assist the Director in making this 

determination. With respect to entrainment, the same range of reductions may be 

expected, and the same reasons the technology is not available still apply. Note that flow 

reductions in general would still be considered for entrainment reduction where 

appropriate at some facilities; see § 122.21(r)(10)(ii). 

	 Seasonal flow reductions: Seasonal flow reductions can significantly reduce impingement 

and entrainment impacts if the peak season(s) for impingement and entrainment is 

avoided. Note the peak season for impingement is not necessarily the same as for 

entrainment. However, seasonal reductions may not be as effective in waterbodies where 

the peak season is of a long duration (e.g., many estuaries have spawning periods 

throughout the year; see DCN 10-6702) or the facility’s period of peak electricity demand 

coincides with critical biological periods (such as mid to late summer). Seasonal 

reductions are not widely used, but a facility may demonstrate the flow reductions 

obtained and apply this reduction as credit towards meeting the IM performance standard 

under the “system of technologies” approach at § 125.94(c)(6). Riverkeeper stated that 

facilities should consider additional technologies during peak spawning periods, 

including outages. EPA disagrees that additional technologies during peak spawning 

seasons should be required of all facilities. The impingement mortality requirements in 

the final rule were developed with data from all seasons, represent an entire year of 

operations, and are therefore reflective of highs and lows in the rate of impingement. The 

Director can establish additional measures for shellfish and other species, where 

necessary, under § 125.94(c)(8) and (9). 

For entrainment, seasonal outages are one possible approach in developing site-specific 

requirements. With respect to entrainment, the same range of reductions may be expected 

as with IM, and the same reasons the technology is not available still apply. While not 

BTA at the national level, flow reductions (in general) could still be considered for 

entrainment reduction where appropriate at some facilities; see § 122.21(r)(10)(ii). One 

commenter noted that seasonal flow reductions may not be available to manufacturing 

facilities. EPA agrees this may be the case for many manufacturing facilities, but notes 

that there are seven compliance alternatives to comply with the IM standard of the final 

rule. Manufacturing facilities are not required to implement seasonal outages, but such 

measures may be established for individual facilities as part of the BTA entrainment 

determination. 

Essay 18 173 
	 Alternate sources of cooling water: Some commenters (including Riverkeeper) note the 

value of using reclaimed water and other alternate sources and commented that EPA 

should include incentives for utilizing reclaimed water. Commenters also indicated that 

EPA has underestimated the availability of reclaimed water. EPA agrees in principle that 

water reuse is a desirable goal, but notes that the availability of alternate sources of 

cooling water is the most critical factor in determining the feasibility. Even if such 

sources existed in adequate quantity, and such sources provided an appropriate quality of 

water to be used as makeup water for cooling, in many cases, a facility may not be 

located in close proximity to the source. It is not cost-effective to haul or pump water 

over long distances. Additionally (and as noted by some commenters), for facilities that 

utilize once-through cooling, an alternative source cannot consistently provide the entire 

volume of cooling water required. The Vidic study cited by Riverkeeper states (first 

sentence of the abstract) that the analysis is based on the premise of using reclaimed 

water as “makeup water in recirculating water systems at thermoelectric power plants.” 

While the Vidic analysis does suggest that some degree of reclaimed water is available at 

many facilities, it is not a logical conclusion to then assume that all existing power plants 

can use a recirculating cooling system in assessing the viability of reclaimed water. 

Further, Vidic lists the availability of reclaimed water (Table 2.5) as being, on average, 

less than 1 percent of the total volume of cooling water used at existing facilities. Given 

the costs and challenges to construct piping between a POTW, for example, and a facility 

(as well as other hurdles), this is neither demonstrated nor feasible for all facilities. EPA 

does not expect many facilities would incur these costs to avail themselves of reclaimed 

water that only comprises 1 percent of their water needs. Therefore, even if all facilities 

were to retrofit to CCRS (as discussed below), and even if all facilities had access to 

reclaimed water sources, all available reclaimed water in aggregate would at best provide 

about 20 percent of total makeup water needs. This is clearly not a feasible and available 

approach for national requirements. 

In practice, this operational measure is usually limited to facilities that employ closedcycle cooling, who then use the gray water as makeup water for the cooling system. The 

State of California extensively examined the use of reclaimed water in its 2008 

California’s Coastal Power Plants: Alternative Cooling System Analysis (see DCN 10­

6964) and noted the limitations to its use on a site-specific level. Overall, the use of 

alternative sources of cooling water is likely to have limited applicability for existing 

facilities. EPA does, however, encourage facilities or permitting authorities to consider 

utilizing reclaimed water on a site-specific basis where appropriate and notes that the 

practice of water reuse does offer two incentives. First, it may provide a facility an 

opportunity to drop below the criteria for inclusion in the regulated universe of the 

existing facility rule (i.e., if the use of alternative sources allows the facility to drop 

below 2 mgd withdrawn or 25 percent use of cooling water) and be regulated purely on a 

BPJ basis. Second, the facility may demonstrate the flow reductions realized and apply 

this reduction towards meeting the IM standard under the “system of technologies” 

approach at § 125.94(c)(6). Lastly, while EPA did not promulgate any national 

requirements related to alternative sources of cooling water, facilities are required to 

consider alternate sources in their permit application submittals under § 122.21(r)(10). 

Essay 18 174 
	 EPA is also aware of technologies that utilize subsurface water withdrawals for cooling 

water, such as Ranney wells and substratum intakes. (For the latter, see DCN 10-6609.) 

These technologies can be effective, but EPA has found that substratum intakes are 

demonstrated for small water withdrawals such as drinking water plants, and are not used 

at industrial facilities such as large power plants or large manufacturing facilities. A 

commenter also noted that requirements to use alternate water sources may 

unintentionally lead to increased groundwater withdrawals. The final rule only requires 

that a facility evaluate alternate sources of cooling water; it does not require a facility to 

utilize groundwater. Also, see Essay 14. As with alternate sources of cooling water, both 

of these subsurface technologies are unlikely to be able to supply the necessary volume of 

water for once-through facilities, limiting their applicability nationally. However, EPA 

encourages facilities to consider utilizing these technologies on a site-specific basis to 

meet applicable requirements. 

	 Facilities may also realize reductions in intake flow by retiring older units. Some industry 

commenters supported an approach where a facility could claim a flow reduction credit 

for a closed unit, while other comments were opposed to any such credit. Some 

commenters suggested that credit for such closures should be provided indefinitely. EPA 

proposed that facilities could obtain credit towards site-specific entrainment requirements 

for unit closures for a period not to exceed 10 years. EPA proposed this time frame 

because it reasonably allows facilities to get credit for flow reductions attributable to unit 

closures, but also requires such facilities to make future progress to ensure its operations 

reflect best available technology. EPA did not receive any data supporting an alternate 

time frame and therefore has retained this requirement for entrainment for the final rule. 

As described in the preamble to the final rule, a facility may consider the flow reduction 

associated with the retirement of a unit for a limited time. EPA notes that, by setting the 

date for which unit requirements may be considered at 10 years prior to the promulgation 

of the final rule, facilities do not have an unlimited ability to claim flow reduction credits. 

This date also effectively sets a “sunset clause” on the unit retirement credit, as facilities 

would not be able to utilize this credit in perpetuity. EPA considers this approach to be 

reasonable because unit retirements, while perhaps not explicitly completed for 316(b) 

reasons, do offer a notable reduction in impacts. EPA also did not want facilities to 

“close” existing units and then operate other units simply to obtain credit for unit 

closures; these reductions would not comprise true reductions of impingent (and 

entrainment). In future years, unit retirement flow credits become less available to 

facilities, new units must comply with different requirements than other existing 

facilities, and facilities will have ample time to plan for future reductions in impingement 

and entrainment using other approaches, as well as planning repowering or other aspects 

of the facility’s operations. 

Some commenters (including Riverkeeper) questioned EPA’s rationale for correlating a 

reduction in flow with a proportional reduction in impingement mortality. As discussed in the 

proposal (see 76 FR 22198), EPA has long held that flow is directly related to impingement and 

entrainment. For example, all other things being equal, reducing intake flow volume by 50 

percent would completely eliminate the impingement and entrainment for those fish and shellfish 

found in that volume of water no longer being withdrawn. Thus the reduced flow intake has 

reduced the rate of impingement and entrainment by 50 percent for that intake. Thus, 

Essay 18 175 
impingement mortality and entrainment mortality would be similarly be reduced by at least 50 

percent. EPA agrees that impingement is subject to other factors (and stated such in the preamble 

cited above) but maintains that the correlation is still appropriate for a national scale regulation. 

EPA notes the commenters did not provide any data to the contrary. However, if a facility can (in 

the future) demonstrate a correlation that is different than what EPA has assumed, the facility can 

opt to comply under the “system of technologies” approach at § 125.94(c)(6). 

With respect to entrainment, some commenters suggest low intake velocity would reduce 

impacts. While reduced intake volume and reduced intake velocity is not the same thing, EPA 

agrees that reducing intake volume should also reduce the intake velocity. However, EPA 

disagrees that low intake velocity significantly affects entrainment (see Essay 15, 16, and 17). 

Exclusion and Collection Technologies

EPA also received comments on a variety of exclusion and collection technologies, as discussed 

below. 

Traveling	 	 	 	 and Passive Screens

Vertical traveling screens are the most common technology at cooling water intake structures, 

and comprise the base technology at about 83 percent of all CWIS (see TDD 4-19). EPA has 

developed impingement mortality standards in the final rule based on the performance of 

modified traveling screens with fish returns such as Ristroph screens, which include a number of 

enhancements and fish protection features over standard traveling screens such as fish buckets, 

improved rails, low pressure spray wash and other removal improvements, and smooth mesh 

screens. EPA agrees with commenters and acknowledges that many types of screens may 

achieve similar performance and could also be determined to meet the impingement mortality 

requirements; this is why EPA did not specify a particular type of modified traveling screen, 

provided certain minimum fish protection feature are present; see rule definitions at § 125.92. At 

proposal, EPA acknowledged that some studies in the record demonstrated a traveling screen 

without all of the fish protection features could achieve performance equivalent to the modified 

traveling screens with fish returns as defined in the proposal. In other cases, the data 

demonstrated traveling screens performed close to, but generally lower than, the performance of 

modified traveling screens with a fish handling and return system. EPA views these studies in the 

record as additional support for BTA in the final rule based on modified traveling screens. In 

other words, if facilities can occasionally achieve the BTA level of performance without all of 

the fish protection enhancements, a facility with all of the fish protection features will be able to 

perform at the BTA level of performance at all times. See Essay 16A for full discussion. 

Riverkeeper provided information on Ristroph screen performance in Appendix B to its 

comments; EPA appreciates the information and notes that for three of the cited performance 

values, Riverkeeper provided citations to actual studies/data. As such, EPA evaluated them as 

part of its development of the impingement mortality performance standard for the final rule. For 

the other three, Riverkeeper provided no references to the studies or the underlying data so the 

information did not meet the data acceptance criteria for the development of the impingement 

mortality performance standard. See TDD Chapter 11 for data acceptance criteria. Commenters 

also discussed several alternative screen designs (e.g., WIP screen, Geiger screen, angled screen, 

Essay 18 176 
                                                            

 

MultiDisc) that could be used to meet the IM standards. EPA agrees that these screen 

technologies can also be effective at reducing impingement mortality, and performance data 

from such designs were included, where appropriate, in developing the final IM performance 

standard; see TDD Chapter 11. As discussed above, the definition of “modified traveling screen” 

in the final rule at § 125.92 specifically describes the screen elements that are needed to achieve 

superior performance, but has not limited “modified traveling screen” to only Ristroph type 

screens. Further, EPA has included a provision in the final rule for a facility to demonstrate that 

its intake technology can perform at or better than the IM BTA – modified traveling screens with 

a fish return. See § 125.94(c)(5) and (7). To the extent new and innovative screen technologies 

come along, these provisions allow a facility to demonstrate BTA level of performance without 

having to comply with the seventh IM compliance alternative that involves continuous biological 

monitoring. 

Several commenters stated that EPA was, in effect, requiring Ristroph screens at all facilities. 

EPA disagrees. The proposed rule at § 125.94(b) would have required compliance with a 

monthly and annual performance standard based on the performance of modified traveling 

screens, but did not require installation of the technology. Similarly, the final rule does not 

require facilities to install modified traveling screens or any other specific technology; the BTA 

impingement mortality standards are simply based on the performance of that technology. (Refer 

to Essay 16.) That said, EPA recognizes that on a site-specific basis, these screens may not be the 

most effective or least costly technology; therefore, in developing compliance costs for the final 

rule, EPA used a cost tool to assign a variety of technologies to model facilities, where the 

technology performance represents one of the final rule IM compliance alternatives and thus 

where the performance is equal or better than that of modified traveling screens. (Refer to 

Essay 21.) 

Other commenters noted site-specific issues that would make implementation of modified 

traveling screens difficult or infeasible. EPA disagrees that difficult installation eliminates the 

technology as a BTA candidate. Difficult or challenging installations may pose additional costs, 

and the final rule cost analysis reflects this.22 See Essay 21. Despite these additional costs, EPA 

concluded the technology is available, demonstrated, and achievable. As noted above, EPA is not 

requiring a specific compliance technology; each facility can select one of seven compliance 

alternatives that will best suit the facility’s conditions to achieve compliance. 

Some commenters noted potential problems with biofouling, such as zebra mussels. As stated in 

the Phase II response to comment document (DCN 6-5049A) in response 316bEFR.027.005, 

EPA acknowledges that biofouling can be a problem at some intakes. However, EPA notes that 

some facilities have historically had issues with biofouling, even in absence of today’s rules and 

have already developed strategies to address it. The record shows that a variety of design and 

operational techniques (e.g., nickel alloy screens, air burst systems, chemical or heat treatments, 

etc.) can reduce the negative effects of biofouling organisms. EPA has not included broadly 

applicable incremental costs to address biofouling that would result from today’s final rule, as 

many facilities are already addressing the issue and incurring these costs. In other words, for 

many facilities this is not an incremental cost of this rule. However, because EPA could not 

22 For example, the final rule does not require barrier nets. The costs of barrier nets were kept in the final rule 

analysis for marine facilities, and may be viewed as an example of additional costs a facility may incur. 

Essay 18 177 
determine with certainty whether other facilities would experience reduced performance of their 

IM technologies without such controls, EPA included some additional costs for model facilities 

located in zebra mussel-prone areas to address costs related to additional O&M or for installing 

alloy screens. EPA finds that the additional costs of these controls is a small part of the total rule 

costs, and the costs did not affect the option selection decision or the rationale for the final rule 

decision. Further, EPA did not receive any data showing that with biofouling controls in place, 

the performance of the model technology is affected. Therefore the potential for biofouling does 

not change EPA’s conclusion that the BTA technologies are available, demonstrated, and 

achievable. 

Riverkeeper supports mandatory fish returns for all intake structures. EPA agrees in principle, as 

contrary to other commenters’ assertions, EPA’s record shows that fish returns are an important 

part of the overall performance of the intake technology. In other words, it is not sufficient to 

remove any impinged fish gently from the screen. The removed fish must also be transported 

back to the source waterbody. For facilities choosing the compliance alternative at § 125.94(c)(5) 

based on optimized operation of a modified traveling screen, the definition of modified traveling 

screen at § 125.92 includes a fish handling and return system with sufficient water flow to return 

the fish directly to the source water in a manner that does not promote predation or reimpingement of the fish. These features are the same features included in EPA’s criteria for 

performance data acceptance in calculating the IM performance standard. In contrast, low intake 

velocity or behavioral deterrent technologies help avoid impingement in the first place, and a fish 

handling return is neither warranted nor applicable. For example, Seabrook is 1.5 miles from the 

source water making a fish return a difficult and more costly proposition, however, the facility 

already has an existing offshore velocity cap and will likely comply per § 125.94(c)( 4). EPA has 

found the offshore velocity cap performance meets the IM standard, and therefore a fish return is 

not part of the velocity cap performance, and is therefore not necessary to meet this IM 

compliance alternative. EPA notes that some states prohibit the discharge of debris (most notably 

Florida), which in some cases includes fish that are impinged and collected. This may limit some 

facilities’ compliance alternatives, but EPA does not find that this poses a constraint on the final 

rule because there are another six compliance alternatives that do not rely on the return of 

impinged fish to their source water. EPA disagrees that the aquatic organisms need to be returned 

to the same source waterbody in all cases. For example, return to a tributary rather than return to 

the original source water may be preferable to prevent re-impingement, predation, and other 

concerns. Therefore, EPA expects the Director would approve the location of a fish return. 

Commenters’ examples of where a fish return is unfeasible are already addressed by either 

innovations in traveling screen technology or by the other IM compliance alternatives. Examples 

include but are not limited to: coastal facilities have already developed fish returns that 

accommodate large tidal variations and address the potential for a fish return with a large vertical 

drop; inland facilities on large rivers have already learned to deal with high debris loads and 

heavy sediment; facilities on the Great Lakes and in the north operate despite freezing 

temperatures and frazzle ice; screen houses are used to enclose traveling screen bays for 

protection from extreme weather conditions; Texas facilities adjust operations to handle large 

seagrass loadings; facilities with intakes on a shipping canal already handle large trash loads and 

navigational traffic constraints; facilities subject to debris loads following a major rainfall event 

have management practices in place to ensure continued operations of their plant; et. al. The 

comments rejecting technology feasibility based on local challenges posed to a given facility did 

Essay 18 178 
not indicate in their comments that any consideration was given to these solutions already 

developed by their peers. In short, every viable manufacturing facility has adapted to ensure an 

available supply of cooling water, and further every power plant has taken the measure necessary 

to ensure condenser pipes remain open and free so that the plant can function. Facilities that fail 

to make these adjustments are not able to offer reliable power, steam, or manufactured products. 

EPA encourages technology transfer and sharing of information between facilities, so that all 

facilities can establish the most cost-effective compliance path available. 

EPA, through its site visits and other data collection, has observed a number of intakes with fish 

returns that are poorly designed or discharge impinged organisms into a trash bin; an inadequate 

fish return can negate any benefits that a well-designed and well-operated screen may offer. EPA 

appreciates the submittal of technical studies on the effectiveness of fish return systems. EPA 

acknowledges that some facilities will face greater challenges when installing a fish return (as 

discussed in several comments; e.g., very long return distances, debris loading, infrastructure 

constraints). EPA has accounted for this comment through revised compliance cost estimates for 

fish returns and O&M for traveling screens. (See the TDD and Essay 21.) EPA also notes that a 

proper fish return system is not required under the other IM six compliance alternatives; for 

example, under § 125.94(c)(1), a facility employing a closed-cycle recirculating system will 

comply with the impingement mortality requirements without adding a fish return system, as will 

the 0.5 fps intake velocity because, as discussed above, it prevents impingement in the first 

place. Lastly, while EPA has eliminated any specific requirements regarding entrapment (see 

below), any organism that is entrapped (e.g., unable to return to the source waterbody due to a 

poor fish return system) must be counted as a mortality in determining compliance with the rule 

under the seventh compliance alternative (i.e., biological monitoring for compliance with the IM 

performance standard). 

Barrier	 	 Nets

In the proposed rule, EPA required performance equivalent to barrier nets as a technology to 

minimize the impingement of shellfish at estuarine and marine intakes. Commenters stated that 

this requirement was not technically feasible for a variety of reasons (e.g., tidal action, vessel 

traffic, biofouling, etc.), as well as noting that EPA did not define the term shellfish. Other 

commenters (including Riverkeeper) stated that shellfish merit protection. EPA proposed this 

requirement because it did not have adequate data on the performance of the BTA technology 

(modified traveling screens) with respect to shellfish. EPA has removed this requirement from 

the final rule because EPA’s revised performance data used to develop today’s final rule IM 

performance standard includes data that incorporate shellfish survival as part of the impingement 

standard. To the extent entrapment of shellfish poses additional concern, the Director may 

establish additional measures, such as seasonal deployment of barrier nets, under § 125.94(c)(8). 

Aquatic	 	 	 	 	 Filter Barriers or AFB

An AFB (sometimes sold under the trade name Gunderboom) operates similarly to a barrier net, 

but typically has a much smaller mesh. More recent versions of the technology are no longer a 

mesh, but rather are comprised of a smooth woven fabric. EPA has studied this technology and 

acknowledges that it can be highly effective for impingement at some facilities, and further may 

be used to reduce entrainment. EPA agrees with commenters that it can be very costly to 

Essay 18 179 
maintain and faces a number of logistical challenges in installation and implementation at some 

locations. Data provided by other commenters shows that recent improvements help mitigate 

previous issues with the technology (such as wave action and tidal influences on the AFB 

tiedowns and posts), and this may result in more frequent application of the technology. The 

technology is not feasible where navigational traffic is a concern, as the AFB is installed as an 

offshore barrier to the intake structure. Furthermore, where EPA has data on AFBs, it is limited 

and primarily for small flow intakes only. As a result of the data and application limitations, EPA 

finds this technology is not demonstrated nor is it available nationally. For these reasons, EPA 

concludes the technology is not BTA. As a result, EPA did not include this technology in its 

compliance cost estimates (i.e., it was not assigned to any model facilities) nor did it include an 

IM compliance alternative specific to AFBs. EPA notes, however, that a facility may consider 

utilizing this technologies on a site-specific basis for entrainment and where appropriate to meet 

IM requirements under § 125.94(c)(6) or (7). 

Cylindrical Wedgewire	 	 Screens

EPA has long recognized the performance of wedgewire screens on impingement. (See, e.g., 

69 FR 41591, where EPA designated wedgewire screens meeting certain criteria including a low 

intake velocity as pre-approved for the now-withdrawn Phase II rule.) Consistent with 

commenters’ assertions and supporting performance data, EPA agrees that wedgewire screens 

are an effective technology for reducing impingement (and therefore impingement mortality) at 

some facilities. However, EPA disagrees that wedgewire screens should be separately considered 

as a pre-approved technology. As noted in the preamble, a properly designed wedgewire screen 

will typically have a design intake velocity of 0.5 fps and would therefore already meet the 

impingement compliance alternative at § 125.94(c)(2). EPA does not have data supporting BTA 

level of performance for a cylindrical wedgewire screen operating at a significantly higher 

velocity. Therefore EPA has no evidentiary basis that would support the inclusion of wedgewire 

screens as a pre-approved compliance technology. Wedgewire screens may also be used to 

reduce entrainment, provided the screen uses fine mesh as discussed further below. 

Fine	 	 	 Mesh Screens

EPA has evaluated the use of fine mesh screens (both fine mesh traveling screens and fine mesh 

wedgewire screens) and is aware of their effectiveness at reducing entrainment of some fish and 

shellfish, but did not develop national BTA requirements based on this technology. In response 

to the commenter stating that EPA had equated the performance of fine mesh traveling screens 

with fine mesh wedgewire screens, EPA’s intent in discussing the two technologies jointly was 

to raise the issue of screen mesh size and the possibility that previously entrained organisms 

could then instead be impinged. As alluded to in EPA’s title of the referenced section in the 

proposed rule preamble (“Entrainment Exclusion Versus Entrainment Survival,” 76 FR 22185), 

EPA specifically recognized that the two technologies operate differently and some studies have 

shown modest performance levels of fine mesh wedgewire screens on exclusion of some 

organisms. However, more commonly EPA found that smaller organisms were simply impinged 

on the fine mesh rather than being entrained by the intake structure (also called “converts”). 

Upon review of the survival of these smaller organisms post-impingement, EPA concludes the 

overall survival was low; see TDD for more discussion. To avoid confusion, EPA proposed a 

framework whereby fine mesh screens could be used for the impingement mortality standard by 

Essay 18 180 
allowing facilities with fine mesh to use a theoretical “3/8-inch sieve.” This regulatory provision 

has been adopted in the final rule, and avoids penalizing a facility using fine mesh for their 

increased impingement of the smaller organisms that would otherwise have been entrained. In 

other words, since course mesh and fine mesh screens would have the same protective effect on 

impinged organisms larger than the 3/8-inch sieve, a facility could use the technology to meet the 

IM performance standard. The facility can then study the site-specific performance for smaller 

organisms as part of the Entrainment Characterization Study. Refer to the preamble and TDD for 

more information, including a discussion of how fine mesh screens impinge organisms that 

would otherwise be entrained. 

The record shows that fine mesh screens generally must be smaller than 1.0-mm mesh to be 

effective at reducing entrainment of larvae, and that the screens must be 0.5-mm mesh to reduce 

entrainment of eggs. More importantly, EPA found that the survival of impinged organisms 

smaller than the 3/8-inch mesh size to be poor; unlike larger and more mature life stages of fish, 

larvae and similar early life stages have little avoidance response, undeveloped skeletal structure, 

and a general lack of mobility. Eggs have no mobility and no avoidance response. Thus while 

fine mesh screens may reduce entrainment, the mean value of entrainment survival is 12 percent; 

see TDD. In addition to the generally poor performance of fine mesh on entrainment, the smaller 

mesh reduces open area for water flow, thus retrofit to fine mesh requires an expanded number 

of screens to maintain the same amount of cooling water flow. This results in at least a doubling 

in size of the intake structure. This is not feasible for intakes with limited shoreline space, or 

intakes with navigational issues; see TDD for further discussion. Thus for national BTA for 

entrainment, EPA rejects fine mesh screens as either available or demonstrated. The Director 

may establish requirements for entrainment based on fine mesh on a site-specific basis, upon 

consideration of the site-specific factors affecting performance of the technology such as intake 

volume, intake velocity, affected species and the relevant life stages, and the intake location 

relative to shoreline. Facilities with AIF greater than 125 mgd would submit this information as 

part of their technology evaluation submitted with the permit application at § 122.21(r)(10) 

Comprehensive Technical Feasibility and Cost Evaluation Study. 

Avoidance/Behavioral Technologies

As explained earlier, avoidance/behavioral technologies may be helpful in reducing impingement 

(and impingement mortality). However, they have not been demonstrated to reduce entrainment 

(e.g., eggs can’t swim and these technologies largely work because the fish are able to swim 

away). Therefore, the following discussions apply to impingement and impingement mortality 

only. 

Reduced	 	 	 Intake Velocity

See Essay 17 for responses to comments on reduced intake velocity. 

Velocity	 	 Cap

Many commenters requested that EPA consider velocity caps as a pre-approved technology. 

EPA disagrees. Based on performance data, EPA did not find that velocity caps by themselves 

performed at the IM BTA level. However, EPA did find that existing velocity caps, in 

Essay 18 181 
combination with a far offshore location, meet the IM BTA level of performance. In the final 

rule, existing offshore velocity caps that meet the definition at § 125.92 would meet the 

impingement mortality compliance alternative in § 125.94(c)(4). See the preamble for additional 

information, including a more detailed discussion of why EPA is not categorically approving all 

velocity caps as an allowed impingement mortality compliance alternative. For velocity caps 

installed after the final rule, a facility could choose § 125.94(c)(6) or (7) to comply with the IM 

standard. 

Acoustic/Behavioral

There are a variety of technologies that will alter the behavior of fish and thus reduce the 

potential for their impingement. See TDD Chapter 6, for examples. The most common 

behavioral technologies include sound and light diversion technologies, however other 

possibilities include louvers and other intakes designed to elicit behavioral responses from fish 

and shellfish. Data in the record indicates that performance of these technologies is highly 

variable and often must be tuned for specific species. For example, EPA is aware of a deterrent 

device tuned for alewife and the performance has been reported to exceed 90 percent reduction 

in impingement. The same device at the same location has little effect on most other species. Due 

to this inconsistent performance, EPA did not consider this class of technologies for national 

BTA for impingement for the final rule, but encourages facilities to consider utilizing these 

technologies on a site-specific basis to meet IM requirements. A facility may demonstrate the 

effectiveness of behavioral technologies if it chooses the systems of technologies impingement 

mortality compliance alternative under § 125.94(c)(6). 

Porous	 	 Dike

As noted by several commenters, another technology that operates on the principle of exclusion 

is the porous dike. EPA agrees that this technology can be effective at some facilities but notes 

that it is not widely demonstrated or available for most facilities due to the need to construct the 

dike into the source water. As a result, EPA did not consider this technology for national BTA 

for impingement but encourages facilities to consider utilizing this technology on a site-specific 

basis to meet IM requirements where appropriate. A facility may demonstrate the effectiveness 

of this technology if it chooses to comply with the “systems of technologies” impingement 

mortality compliance alternative under § 125.94(c)(6). 

Entrapment

In the proposed rule, EPA included requirements to minimize the impacts to fish and shellfish 

that are entrapped in an intake. (See 76 FR 22204.) Many industry commenters questioned the 

feasibility and cost, as well as whether the issue was sufficiently common to necessitate a 

national requirement. Riverkeeper noted that it is important to protect entrapped fish. Further, 

EPA received various comments that question the costs of both monitoring and compliance for 

such a requirement. 

After consideration of all the comments and data, EPA has not adopted any specific technology 

requirements for entrapment in the final rule. In the final rule, facilities that elect to comply with 

the IM standard under § 125.94(c)(7) must include entrapped organisms as mortality and 

facilities that comply with an IM alternative that requires an optimization study must account for 

Essay 18 182 
all impinged fish and shellfish when conducting their 2-year performance study. To the extent 

entrapment of shellfish poses a concern, the Director may establish additional measures, such as 

seasonal deployment of barrier nets; see the preamble for additional details. EPA noted that it has 

limited data as to the prevalence of entrapment as a national problem and did not receive any 

new comments or information that suggests otherwise. However, to avoid a potential loophole in 

which fish are not impinged but are not able to escape the cooling water system, the standards for 

IM require that any organisms that are entrapped must be counted as mortalities when 

determining the IM survival rates for compliance. EPA disagrees with the comments that this 

provision is under costed as discussed below. Therefore, the rule does provide for an accounting 

of entrapped organisms. More specific responses are discussed below. 

Based on site visits and other information in the record, the scenarios in which entrapment was 

identified as most likely to occur involve screens at a forebay where there is no fish handling and 

return system. If the cooling system provides no means for escape, entrapment may occur; the 

comments are not relevant to those intakes with access to the forebay or some other means for 

escape. In site visits, EPA observed this scenario occurred with intake canals and offshore 

velocity caps. In the case of offshore velocity caps, a fish handling and return could involve a 

return flume that is sufficiently lengthy as to cause mortality and/or predation during the return. 

Therefore EPA agrees with comments noting the lengthy fish return may cause feasibility issues 

or significant additional costs, such as at Seabrook Station or Cook Nuclear, and may not, in fact, 

be effective. On the other hand, EPA visited the St. Lucie nuclear power plant in Florida, which 

employs an offshore velocity cap to withdraw water into an enclosed onshore canal system. 

Conceptually, this scenario could lead to entrapment. Due to concerns over impacts to 

endangered sea turtles that are occasionally drawn into the canal, St. Lucie has set up a series of 

barrier nets in the canal and employs several full-time biologists to capture the turtles and return 

then to the ocean, thereby addressing the entrapment issue. This example shows how entrapment 

was addressed on a case-by-case basis to protect specific species as needed. 

Despite the potential for some degree of entrapment with an offshore velocity cap, based on 

performance data EPA concludes existing offshore velocity caps meet or exceed the performance 

of the IM BTA – modified traveling screens with fish return. Therefore no additional 

requirements or biological monitoring would be required under the IM compliance alternative in 

§ 125.94(c)(4), and EPA disagrees that additional costs would be incurred. In response to the 

comment that a single organism may slip through and become entrapped, it is both unreasonable 

and unrealistic to assume that a single organism would result in a facility being out of 

compliance with the IM standards. In any event, no data was provided supporting this assertion. 

In the case of an intake canal, EPA disagrees that the costs of monitoring are considerable, as the 

final rule does not impose biological monitoring requirements in perpetuity for any of the IM 

compliance alternatives at § 125.94(c)(1) through (6); § 125.94(c)(7) is the only alternative that 

requires biological compliance monitoring, and that alternative’s costs already include 

monitoring. In addition, any monitoring required for modified traveling screens under § 

125.94(c)(5) is already costed as part of the two year performance optimization study required at 

§ 122.21(r)(6). Therefore, any entrapment would already be counted during the performance 

optimization study, submitted as part of the permit application, and the results reviewed by the 

Director. As EPA expects the majority of facilities will comply with § 125.94(c)(1) through (5), 

EPA anticipates that only in limited cases would additional requirements be necessary. Thus the 

rule specifies the Director can develop additional requirements including monitoring at § 

Essay 18 183 
                                                            

 

125.96(a), or additional technology requirements for protection of shellfish at § 125.94(c)(8) or 

fragile species at § 125.94(c)(9). 

Nuclear Facilities

Commenters stated that nuclear facilities merit special consideration under the final rule. EPA 

studied this issue in the Phase II rule and coordinated with Nuclear Regulatory Commission 

(NRC) staff on safety concerns. The Phase II proposal states: 

“Finally, EPA has coordinated with the staff from the NRC in the development of 

this proposed rule to ensure that the proposal does not conflict with NRC safety 

requirements. NRC staff have reviewed the proposed 316(b) rule and did not 

identify any apparent conflict with nuclear plant safety. NRC licensees would 

continue to be obligated to meet NRC requirements for design and reliable 

operation of cooling systems. NRC staff recommended that EPA consider adding 

language which states that in cases of conflict between an EPA requirement under 

this proposed rule and an NRC safety requirement, the NRC safety requirement 

take precedence. EPA has added language to address this concern to the proposed 

rule.” (67 FR 17127, April 9, 2002) 

Based on this information, EPA agrees to the extent that there may be safety concerns, the 

Director may consider alternative provisions. EPA also placed a document in the Phase II record 

that describes this coordination with NRC; see DCN 4-00016Q. EPA received similar comments 

about nuclear facilities in the Phase II rule and addressed them in the same way; refer to the 

Phase II response to comment document at DCN 6-5049A. To this end, EPA has included § 

125.94(f) in the final rule to account for safety-related concerns. EPA also notes that § 125.94(f) 

in today’s final rule is essentially the same as the language from the 2004 final Phase II rule; see 

§ 125.94(f) at 69 FR 41687 (July 9, 2004). 

With respect to general operations (especially the day-to-day operations of a cooling water intake 

structure), EPA disagrees that nuclear facilities are substantially different than other facilities. 

EPA recognizes that nuclear facilities may still require cooling water withdrawals even when 

they are not generating electricity to dissipate heat from the fuel rods. EPA also recognizes that 

not all nuclear facilities are primarily electric generators; a handful of such facilities are research 

units or used for other purposes. But in general, nuclear generating units operate in a manner 

very similar to fossil-fueled plants with respect to cooling water use. Additionally, the rule 

provides several compliance options the facility could select. For example, commenters question 

the additional risk and cost of having biological staff onsite to conduct impingement mortality 

sampling. A facility could select one of the seven IM compliance options that does not require 

biological compliance monitoring and avoid these issues entirely. EPA also notes that many of 

the problems cited by commenters, such as the need for increased security measures, are not 

issues of feasibility, but rather of cost.23 While EPA agrees this is an important consideration, 

cost alone is not a factor in assessing the technical feasibility of impingement requirements for 

23 One commenter mentioned the need to potentially install grates across fish returns to ensure a secure perimeter, 

which may affect the survival of fish in the return trough. EPA disagrees, as most fish returns are relatively small (a 

foot or two in diameter at most) and any grating could be sized to permit the passage of fish unimpeded while still 

excluding human entry. 

Essay 18 184 
nuclear facilities. Other commenters noted that many nuclear facilities have already studied 

impingement and entrainment as part of developing other documents, suggesting the need for 

increased security measures is an issue that the industry has already resolved. 

Commenters also questioned the timeframe for compliance for nuclear facilities. Because nuclear 

facilities are generally baseload facilities, and have longer times between scheduled outages 

(such as refueling), EPA agrees that nuclear facilities may require more time to comply with any 

requirements. This has been addressed at § 125.94(a) and (b), allowing the Director to establish 

the schedule for implementing the final rule requirements. As a result, the final rule allows ample 

time for the facility and the Director to comply with any impingement or entrainment 

requirements. Commenters stated that nuclear facilities should be allowed to consider the 

remaining useful life of a generating unit. EPA agrees this is an appropriate consideration for 

entrainment requirements, and has included considerations for units that are approaching 

retirement in § 122.21(r)(1)(ii)(F-G) and as one of the factors for the Director to review in 

establishing site-specific entrainment requirements (see § 125.98(f)(2)(iv)). EPA notes that 

nuclear generating units often are relicensed for 10 or 20 years, and that such extension of useful 

life should also be considered. Commenters also noted that nuclear facilities may have already 

studied impingement and entrainment as part of developing other documents (e.g., NEPA); EPA 

appreciates that some effort may have been dedicated to this analysis, but cannot rely on these 

documents as the sole source of information to make a BTA determination. In some cases, for 

example, impingement and entrainment may be a minor area of focus. EPA notes that the facility 

can utilize any data collected or analyses completed in submitting materials under 316(b) and 

may, as a result, already meet some of its permit application requirements. 

Riverkeeper argued that the provision for nuclear facilities is unwarranted, or, at a minimum, 

should be revised to a previous version. EPA disagrees that the provision is unwarranted; EPA is 

not the nuclear expert and is not in a position to fully assess nuclear safety issues on a sitespecific basis. As noted below, EPA agrees that there may be cases where nuclear safety is not a 

concern, but EPA is unable to make that determination on a national scale. The commenter also 

argued that a previous version of this provision was superior because the revised language 

weakened other requirements. EPA disagrees that these changes from the proposed rule 

weakened the requirements for nuclear facilities. The language is generally very similar and can 

be relevant for either impingement mortality or entrainment; this is appropriate, given that 

conflicts with nuclear safety could result from requirements for either one. Additionally, the 

deletion of consideration of technical feasibility from this provision did not eliminate the 

Director’s authority to consider technical and cost considerations in determining BTA. As 

discussed in the preamble, cost is one factor to consider in establishing BTA and the Director 

will weigh cost considerations along with technical considerations. 

Commenters also noted that the NRC must be consulted as part of establishing any new 

requirements for 316(b); EPA agrees in principle and has retained the provision at § 125.94(f) to 

facilitate this review. One commenter notes that EPA has no authority over nuclear issues, 

particularly with respect to safety. EPA agrees and notes that the final rule does not supersede 

authority residing with the NRC. However, EPA maintains that the final rule’s requirements are 

sufficiently protective of safety concerns at nuclear facilities (and NRC agrees, as documented in 

the Phase II rule), as provided for in § 125.94(f). 

Essay 18 185 
                                                            

Several commenters noted EPA’s discussion in the proposed rule TDD regarding the cooling 

system at Palisades Plant. Primarily, this discussion was intended to establish that there has, in 

fact, been a nuclear facility that has retrofitted to closed-cycle cooling, in contrast to numerous 

statements made previously by industry that such a retrofit has never been demonstrated. EPA 

refers to DCN 10-6888B in the record, titled “Application for Reactor Construction Permit and 

Operating License Amendment No 21.” This correspondence from the facility to the Atomic 

Energy Commission (now the NRC) states “[a]mendment No. 21 adds new material to sections 

10 and 11 of the FSAR to describe modifications to the condenser cooling and the liquid 

radwaste systems that the Company plans to install in the future, after initial operation. The 

condenser cooling system modification involves the addition of a cooling tower or towers to 

change the existing once-through system to a system which is closed-cycle except for makeup 

from, and blowdown to, Lake Michigan.” A plain reading of this document, as well as 

information provided in comments from the facility’s current owner,24 indicates that the cooling 

towers were installed after the facility began operating with a once-through cooling system. EPA 

also placed a number of documents related to Palisades’ cooling system in the record for the 

Phase II rule. These documents further support Palisades did, in fact, retrofit its cooling system.25 

EPA agrees that considerations for 316(b) do not appear to have been a direct factor.26 EPA also 

agrees that there were unusual circumstances surrounding this facility and it appears that changes 

were made to the design of the cooling system in the midst of construction or in early stages of 

operation; there is no doubt that the retrofit at Palisades has a complicated history. However, the 

documentation continues to indicate that the cooling towers were installed after the facility had 

operated for approximately two years using a once through cooling system, which does 

constitute a retrofit. EPA also provided this documentation in the record to demonstrate that, at 

some nuclear facilities, it may be possible to separate the cooling system related to waste heat 

from electricity generation from the cooling system related to maintaining system safety within 

the reactor. If this is the case (as it appears to have been at Palisades), nuclear safety concerns 

may not be a significant issue in evaluating the feasibility of retrofitting to closed-cycle cooling. 

EPA, however, does not interpret this instance of a retrofit to indicate that all nuclear facilities 

may be able to retrofit to closed-cycle cooling. As noted in the preamble, there are many factors 

that affect that decision. 

24 See EPA-HQ-OW-2008-0667-2347-A2, summarizing the Phase II proposed rule TDD; “The facility began 

operating in early 1972 utilizing on a temporary basis a once-through cooling system. The main portions of the 

tower system were constructed in 1972 and 1973, while the plant operated in a once-through mode. After a tenmonth outage, the conversion to a closed-cycle recirculating system occurred in May 1974, when the cooling towers 

became operational.”

25 See DCN 4-2502, which states “Mr. Gulvas [an employee of Consumer Energy] also stated that he knew of no 

other facility that had gone through a retrofit like the Palisades facility.” This document also referred to “the historic 

conversion of the plant’s cooling system from once-through to recirculating with cooling towers.” DCN 4-2529, 

written by Mr. Gulvas, also refer to “the conversion of the once-through cooling system to cooling towers.” See also 

DCN 4-2530 for similar discussion. 

26 DCN 4-2529 from the Phase II rule indicates that radwaste and thermal discharges were the primary concern of 

the citizen organizations that petitioned for the retrofit. 

Essay 18 186 
Essay 19: Regulatory Options

Introduction

EPA identified 4 options considered at proposal: 

Option 1: Impingement mortality (IM) controls based on modified traveling screens for all 

facilities with flow greater than 2 million gallons per day (mgd), closed-cycle cooling or its 

equivalent for new units, and a site-specific determination of entrainment BTA for all other 

facilities. 

Option 2: Intake flow commensurate with closed-cycle cooling for facilities that have a design 

intake flow of greater than 125 mgd and IM controls based on modified traveling screens for all 

facilities with flow greater than 2 mgd. 

Option 3: Intake flow commensurate with closed-cycle cooling for all facilities and IM controls 

based on modified traveling screens, for all facilities with flow greater than 2 mgd. 

Option 4: Impingement mortality (IM) controls based on modified traveling screens for all 

facilities with flow greater than 50 mgd, closed-cycle cooling or its equivalent for new units, and 

a site-specific determination of entrainment BTA for all other facilities and of impingements 

mortality controls for facilities with flow less than or equal to 50 mgd. 

General Response

As described in the preamble to the final rule, EPA adopted a modified version of Option 1 for 

the final rule. EPA has developed a final rule that establishes “best technology available” 

standards for cooling water intake structures that minimize adverse environmental impacts. 

Specifically, the final rule establishes BTA standards for reducing impingement mortality and 

entrainment, the adverse environment impacts that EPA identified as associated with cooling 

water intake structures. First, for existing power generating facilities and existing manufacturing 

and industrial facilities that withdraw more than 2 mgd per day from waters of the U.S., at least 

25 percent of which is used exclusively for cooling water, the rule establishes a BTA 

impingement mortality performance standard based on the performance of modified traveling 

screens with fish returns (often referred to in this essay simply as modified traveling screens) and 

that provides seven different alternatives for complying with the standards. Second, for existing 

facilities, the rule establishes a BTA standard for entrainment that requires the determination of 

required entrainment reduction measures in a structured site-specific permitting proceeding. The 

BTA standard for entrainment requires that certain prescribed factors must be considered in the 

decision and must reflect the maximum reduction in entrainment warranted after consideration of 

relevant factors. In addition to the above provisions, which apply to existing CWIS units at 

existing facilities, the rule establishes a BTA standard, for both impingement and entrainment, 

for new units at existing facilities. Under this standard, new units at existing facilities will be 

subject to requirements similar to the section 316(b) requirements for new facilities subject to the 

previously promulgated Phase I rule. This essay discusses the requirements for existing facilities 

only. See Essay 20 for a discussion of the new unit provisions. 

Essay 19 187 
                                                            

As described in Section VI of the preamble, EPA examined the full range of technologies that 

reduce impingement mortality or entrainment or both.27 After considering a full range of factors 

(see Essay 10 and Section VI of the final rule preamble), EPA has concluded that it should base 

the impingement mortality standard for existing units on the performance of modified traveling 

screens because modified traveling water screens28 are the “best technology available” for 

minimizing impingement mortality. While EPA identified a number of technologies that perform 

as well or even better than traveling screens, these technologies are either not feasible or 

available on a nationwide basis and thus are not the “best technology available” for standard 

setting purposes. See Section VI of the final rule preamble. Moreover, the impingement mortality 

standards for existing units provides a number of compliance alternatives that include these other 

equally effective or better performing technologies that while not available nationally, may be 

available for some sites. See Section VI of the final rule preamble. EPA based the BTA 

impingement mortality standard for existing units on the performance of traveling screens 

because EPA concluded that this technology is effective, widely available, feasible, and does not 

lead to unacceptable non-water quality impacts. 

As explained in Section VI of the preamble, EPA has not identified a technology or 

combinations of technologies that EPA concluded is “best technology available” for minimizing 

entrainment at existing units. EPA did not identify a technology for reducing entrainment that is 

effective, widely available, feasible, and does not lead to unacceptable non-water quality 

impacts. As such, EPA is unable to identify a nationally applicable BTA technology on which to 

base the BTA entrainment standard. 

While EPA concluded that flow reduction commensurate with a closed-cycle recirculating 

system such as a cooling tower reduces entrainment (and impingement mortality) to the greatest 

extent and is a most effective performing technology, after careful consideration of multiple 

factors, EPA concluded that closed-cycle is not the “best technology available” for existing units 

within the meaning of the statute. It is not the best technology available on a national basis for 

minimizing adverse environmental impact and should not form the sole basis for the BTA 

standard for entrainment. For the final rule, EPA has identified three factors as significant in its 

decision to reject closed-cycle cooling as the technology basis for a national BTA entrainment 

standard. The three factors that collectively support rejecting closed-cycle cooling systems as a 

widely applicable BTA for existing facilities (except new units) are land availability, increased 

air emissions, and remaining useful life. The record shows that though closed-cycle cooling is 

effective and a high performing technology, it is neither widely available nor feasible, and has 

unacceptable non-water quality impacts in some instances. While EPA cannot identify with 

precision the extent of these limitations on installing closed-cycle cooling systems nationwide, 

the record indicates that the circumstances are neither isolated nor insignificant. EPA also 

considered other forms of flow reduction including variable speed drives and seasonal outages. 

EPA found that these were not available and not BTA; see Essay 18. 

EPA also determined that there were no other “available” technologies for entrainment whose 

performance came close to that of closed-cycle recirculating systems. For example, fine mesh 

27 Some technologies only reduce impingement (or IM), and have no effect on entrainment. Therefore EPA 

considered each technology’s performance for IM and entrainment separately. 28 Defined at 40 CFR 125.92 to include any traveling screens with the same fish-friendly and protective features as
 

modified traveling screens with fish-friendly fish returns.
 

Essay 19 188 
screens reduce entrainment mortality by only 12 percent on average. See Essay 18 for further 

discussion. See the TDD for EPA’s analysis showing that there are no intermediate performing 

technologies for entrainment. 

Further, while reduced intake velocity was a very effective control for impingement mortality 

and may also reduce entrainment of some life stages of fish and shellfish, it does not 

significantly reduce entrainment of eggs and non-motile stages of larvae. As discussed in the 

preamble, in almost all cases entrainment results in 100 percent mortality. However, even if 

reduced intake velocity was effective for entrainment, EPA has already rejected the technology 

for consideration as BTA because it is not physically available in many locations. See Section VI 

of the preamble and Essay 17. 

Because EPA did not identify any single technology or group of technology controls as the basis 

for establishing the national performance standard for entrainment for existing units, EPA’s 

national BTA entrainment standard for existing units puts in place a framework for establishing 

entrainment requirements on a site-specific basis. The framework specifies factors that must be 

considered in the Director’s determination of the BTA controls. 

Factors for Supporting Site‐Specific Entrainment and Rejecting a Uniform Standard

Based On Closed‐Cycle Cooling

Riverkeeper commented that EPA illegally uses the four factors to justify site-specific 

entrainment standards. The statutory directive requiring facilities to adopt the best technology 

cannot be construed to permit a facility to take measures that produce second-best results. In the 

view of Riverkeeper, EPA itself proposes easy solutions to the problems and none of these 

reasons provides enough grounds for instituting site-specific BTAs industry-wide. EPA 

disagrees. For the reasons explained above and in preamble Section VI, EPA has determined that 

the most effective technology, closed-cycle cooling, is not sufficiently available to provide the 

technology basis for the national BTA entrainment standard. More specifically, for the final rule, 

after a full consideration of all factors, EPA determined three factors that collectively support 

rejecting closed-cycle cooling systems as a uniformly applicable BTA for existing facilities 

(except new units) are land availability, increased air emissions and remaining useful life. The 

commenter discusses and dismisses each factor individually, but does not consider them in 

aggregate. While EPA cannot identify with precision the extent of these limitations on installing 

closed-cycle cooling systems nationwide, the record indicates that the circumstances are neither 

isolated nor insignificant. Each of these and the comments received are discussed in more detail 

below. In establishing a national standard that requires determination by the Director on a sitespecific basis of required entrainment controls in a structured proceeding requiring consideration 

of identified elements, EPA also has not ruled out closed-cycle cooling as an appropriate BTA 

control measure for individual sites. Rather, EPA would expect that, where appropriate, the 

Director will determine that closed-cycle cooling is the required control for entrainment under 

the BTA standard. See preamble Section VI and Essay 10 for a discussion as to why an informed 

decision resulting in a site-specific determination by the Director is an appropriate approach in 

absence of an identified national BTA. 

Commenters indicated that it would be arbitrary and capricious for the EPA to force an existing 

facility to completely redesign its facility by installing closed-cycle cooling. EPA first notes that 

Essay 19 189 
retrofit to closed-cycle does not require a facility to completely redesign; see Phase I and Phase 

II discussions of facilities that have already completed a retrofit to closed-cycle. The retrofit to 

closed-cycle has been incorporated at both power plants and manufacturing facilities. Some 

manufacturers have even retrofitted dry cooling on certain unit processes within the facility; see 

site visits in the record for more examples. The rule requires as part of the 40 CFR 122.21(r)(10) 

Comprehensive Technical Feasibility and Cost Evaluation Study a description and discussion of 

closed-cycle cooling, fine mesh screens, water reuse, and alternate sources of cooling water. 

Each of the three factors that support EPA’s determination that closed-cycle is not BTA 

nationally must also be evaluated. Therefore, EPA disagrees that the site-specific requirements 

for entrainment reduction, which may include closed-cycle cooling if determined to be 

appropriate by the Director, will be arbitrary or capricious since the Director will carefully 

consider all issues raised by the facility in the permit application documents. 

Land Availability

EPA received a number of comments concerning the use of land availability as a factor for 

rejecting a uniform standard based on closed-cycle cooling. Some disagreed with EPA’s 

proposal analyses saying that EPA cited 25 percent as not having sufficient land but then stating 

that some of those 25 percent would likely find a way around the land availability issue. 

According to them, that leaves a small percentage of facilities that would be unable to retrofit to 

cooling towers because of limited space. They also note that EPA based this decision on an inline tower design and that EPA did not consider a back-to-back configuration that would require 

only 17 percent of the space required for two side-by-side in-line towers. Riverkeeper 

commented that allowing potential space-constraint considerations at some sites to justify a caseby-case approach for all facilities, as EPA has done in the Proposed Rule, is arbitrary and 

capricious and that even if there are arguable site constraints, the use of eminent domain for 

matters relating to power transmission and generation (as well as a variety of other public goods 

and services) is well-established and should not be ruled out in this context. 

EPA reviewed the record for the final rule and notes that there is little detailed data available 

regarding availability of land on a national basis. First, EPA has reviewed all of its site visit 

reports including an evaluation of the size of each site. EPA agrees that in some circumstances, 

some facilities with a small parcel of land could still install closed-cycle cooling by using 

creative engineering solutions. On the other hand, EPA found that some facilities even large sites 

could not feasibly install cooling towers because of local zoning requirements or other local 

concerns. Second, EPRI submitted results of a survey that asked “Does your facility have 

contiguous open space on your property or adjacent ‘offsite’ open space that can be used to 

support cooling tower construction?” Twenty-three percent of facilities responded definitely that 

they did not. (DCN 10-6927). Similar to the facilities where EPA conducted site visits, EPA 

expects that some of these facilities may be able to install cooling towers using creative 

engineering solutions. However, EPA does not have the information or the capability to assess 

these situations. Third, further review has shown that setback distances to mitigate noise and 

plume abatement (based on GPS mapping of residential areas) act as an additional constraint on 

land available for retrofitting to closed-cycle. Finally, EPA also recognizes that some facilities 

may be able to purchase new land, but is aware that in space constrained areas such as urban 

areas, such land may not be readily available, and/or costs may be prohibitive. Consequently, 

EPA estimates that as many 25 percent or more of facilities might have one or more constraints 

Essay 19 190 
on land availability that would limit retrofit of cooling towers for the entire facility. EPA lacks 

adequate support to indicate that land constraints can be accommodated at existing facilities, and 

commenters did not provide supplemental data to support the alternative. 

Regarding back-to-back cooling towers, EPA agrees that back-to-back cooling towers use less 

space, but disagrees this tower configuration is demonstrated as available for locations that 

require plume abatement. EPA estimates abatement would be required at approximately 25 

percent of closed-cycle systems, and commenters have not provided any data to the contrary. 

EPA notes that requirements for plume abatement tend to occur at facilities with small buffer 

areas that are also located in close proximity to roadways and housing/urban development. 

Facilities in these locations also tend to be much more likely to be subject to space constraints. 

Thus, a back-to-back tower design may not be widely available to many facilities with space 

constraints. 

With respect to the comment about eminent domain, to the extent that eminent domain is a 

legally available option to acquire land to retrofit to cooling towers, it may not, in fact, be an 

option because of public opinion or other constraints. For example, the power station may be 

located in a populous area. Environmental Justice (EJ) or other public opinion issues may 

constrain further expansion. In any event, EPA cannot assume the broad availability of eminent 

domain as a cure-all for geographical or land limitations. 

Finally, EPA disagrees that allowing potential space-constraint considerations at some sites to 

justify a case-by-case approach for all facilities is arbitrary and capricious. First, EPA notes that 

it rejected cooling towers on the basis of three factors combined. For a response to the comment 

about EPA’s selection of a site-specific BTA standard, see Section VII of the preamble and 

Essay 10. 

One commenter stated that refusal to set cooling towers as BTA because of a desire to save room 

for new units is unacceptable noting that land needed for the retrofit would later be required for a 

new unit when new units are already required to seek viable alternate sites. While EPA did use 

land availability as a consideration in its decision to establish entrainment requirements on a sitespecific basis, EPA’s discussion of the potential competing land requirements for exiting unit 

cooling towers and new units was only described to highlight the potential tradeoffs involved. 

Saving land for possible future new units was not a consideration in this decision. 

Other commenters agreed with EPA that land availability was a limiting factor at many facilities 

stating numerous concerns such as the need to locate towers a sufficient distance from equipment 

that would be damaged by drift or ice formation; local zoning requirements; the potential for 

tower foundations to interfere with groundwater movement away from infiltration ponds that 

treat wastewater from the facility; and location of available land in relation to the location of 

process units that require cooling water. While EPA did not specifically cite such concerns, EPA 

agrees that such considerations may affect the availability and costs of a closed-cycle cooling 

systems and expects that, depending on site-specific conditions, these concerns may be some of 

the many issues that will be taken into consideration by the Director in determining site-specific 

entrainment requirements. 

Essay 19 191 
                                                            

Commenters argued that requirements to purchase land to accommodate entrainment control 

technologies is unlawful and inappropriate and cited a legal precedent They state that the Clean 

Water Act does not authorize EPA, or the States, to require enlarging a site and that EPA should 

eliminate any suggestion that facilities examine the availability and feasibility of purchasing 

additional land. EPA notes that the final rule does not establish a requirement based on cooling 

towers. Furthermore, the final rule does not require a facility to purchase adjacent land nor is 

there an implied requirement to demonstrate infeasibility. The final rule preamble language has 

been revised to state that the Director must provide a discussion explaining how issues 

concerning land availability, insofar as they relate to the feasibility of adoption of an entrainment 

technology, were addressed in the site-specific determination. For example, a discussion of land 

availability might include an evaluation of adjacent land, and acres potentially available because 

of generating unit retirements, production unit retirements, other buildings and equipment 

retirements, ponds, coal piles, rail yards, transmission yards, and parking lots; decommissioning 

of existing units; repurposing of existing land uses; documentation that insufficient acres are 

available on-site; and evidence of the feasibility of the purchase or other acquisition of property 

adjacent to the facility. In particular, EPA is aware of corporate level ownership of multiple 

adjacent parcels of land, and it is appropriate for these parcels to be considered. Issues regarding 

the feasibility and legality of requiring the purchase of adjacent land can be determined on a sitespecific basis. 

Increased Air Emissions Could Be a Factor on a Local Basis

Many commenters agreed with EPA’s assessment regarding the potential for increased air 

emissions associated with closed-cycle cooling. In particular, there was concern that PM2.5 which 

is generated by drift from the cooling towers themselves may cause permitting problems. They 

note that air permits may need to be reopened and that the ability to obtain new permits is 

uncertain. EPA agrees that this may be a problem in a number of locations and has considered 

increased air emissions as a significant factor supporting the decision to require site-specific 

determination of entrainment requirements. 

Riverkeeper commented that air emissions would not increase as a result of closed-cycle 

requirements because the recent air emission regulations and the trend in the power industry of 

switching away from coal to natural gas have resulted in a downward trend in air emissions 

nationwide. They also note that replacement power may come from cleaner sources and that 

some facilities may choose to repower using less polluting fuels and technologies. They suggest 

that the result of these factors will be that closed-cycle cooling may simply result in a slightly 

less dramatic decrease in emissions. EPA disagrees. Retrofitting closed-cycle cooling (without 

also repowering) would result in increased air emissions of various pollutants, including 

particulates, sulfur dioxide, nitrogen oxides, mercury, and greenhouse gases, among others.29 As 

a result of installing closed-cycle cooling structures, fossil-fueled facilities would need to burn 

additional fuel, thereby emitting additional PM, CO2, SO2, NOX, and Hg. Two factors are 

responsible: (1) the need to compensate for energy required for operating cooling towers, and 

29 EPA recognizes that retrofitting closed-cycle cooling could be combined with other energy efficiency or pollution 

control technologies with the net effect of reducing air emissions; however, facilities could (and may be required to 

under other rules) install such technologies anyway, without converting to closed-cycle cooling. Comparing closedcycle cooling to once-through cooling with all other technologies held constant, there is an energy penalty for the 

auxiliary power consumption that would lead to greater air emissions. 

Essay 19 192 
(2) slightly lower generating efficiency attributed to higher turbine backpressure when the 

condenser is not replaced with one optimized for closed-cycle operation when retrofitting 

existing units (also referred to as the energy penalty). While both of these contribute to increased 

air emissions, the larger contributor by far to projected increased air emissions results from the 

energy penalty. 

The impact of the increased emissions varies according to the local circumstances. The increased 

emissions could consist of stack emissions from increased fuel usage, cooling tower emissions, 

and plumes of water vapor. EPA’s analysis suggested that the most significant impacts would be 

increased PM2.5 emissions, which are associated with an increase in human health effects. EPA 

notes that cooling plume abatement and drift elimination technologies exist to address cooling 

tower emissions. EPA has included costs for such technologies in its analysis of Proposal 

Options 2 and 3. Since EPA did not reject closed-cycle on the basis of cost, the added expense of 

these additional control measures was not a basis for rejecting closed-cycle. Further, EPA 

expects most effects of the particulates from cooling tower emissions would be limited to the 

immediate vicinity, confined wholly to the facility property. (See DCN 10-6954.) Therefore, 

EPA’s primary concern here is increased air emissions associated with additional fuel usage due 

to the so-called energy penalty when retrofitting to cooling towers. EPA’s review of emissions 

data from E-GRID (year 2005) suggests that impacts from these pollutant discharges could be 

significant. These potentially include the human health and welfare and global climate change 

effects – all associated with a variety of pollutants that are emitted from fossil fuel combustion. 

EPA is not able to quantify the frequency with which facilities could experience these local 

impacts, and therefore has concluded that the proper forum to address such local impacts fully is 

in a site-specific setting. 

One commenter (2181.016) stated that EPA failed to fully evaluate the air emission impacts of 

requiring closed-cycle cooling for new units. Since new units have not been designed or 

constructed yet, EPA has no way of reasonably estimating the net difference in air emissions that 

would occur as a result of new unit requirements. However, in the Phase I rule for new facilities, 

EPA found such impacts for newly constructed facilities were acceptable. The new facility will 

produce additional emissions, and the additional emissions for closed-cycle are a very small 

portion of total emissions. EPA further concludes that since there are far fewer emissions from 

new units compared to emissions from new facilities, primarily because there is no energy 

penalty associated with new units because the condenser can be selected to compensate for 

higher turbine backpressure, that any such incremental air emissions impacts would be 

acceptable. As described in the Basis for the Final Regulation section of the preamble, EPA has 

concluded that the new unit requirements will not pose an unacceptable air emissions impact. 

See Essay 20 for further discussion of new units. 

Remaining Useful Plant Life Could Be a Factor on a Facility Basis

EPA received several comments regarding consideration of useful plant life as a factor in the 

availability of certain technologies for controlling entrainment at a particular facility. Some 

agreed with EPA that significant investment in closed-cycle cooling for short-lived units is not 

economical. Most expressed a desire that EPA establish some sort of defined exemption from 

BTA requirements for units that are planned for retirement or a requirement for a clear trigger for 

automatic reopening of permits if an exempt unit planned for retirement should pursue an 

Essay 19 193 
extension of unit life. Those requesting exemptions for future retirements gave examples of 

where an existing facility has formally committed, or will formally commit, via a legally binding 

instrument to retire within a specified time (e.g., 5 or 10 years) of the effective date of the final 

rule or would occur prior to the proposed eight-year compliance deadline. Commenters also 

stated that EPA should remove study and compliance requirements for planned early retirements 

or closures. 

Remaining useful life is perhaps the most difficult parameter to evaluate on a national basis for 

several reasons. EIA and EEI analyses show that uncertainty in fuel prices and profitability of 

certain fuel types could result in different sets of facilities likely to close. Further, while the 

facility age may be used as an indicator of remaining useful life (see TDD Chapter 4), other 

factors make the facility age irrelevant, such as: license extensions at nuclear facilities; 

repowering at fossil-fuel power plants; replacing existing units sequentially at a facility; addition 

of newer more efficient units; replacement of existing product lines; addition of new product 

lines; and other construction and upgrade projects. For example, several nuclear facilities that are 

several decades old have completed Type III uprates and obtained relicensing for another 20 

years; oil-fired power plants have repowered to NGCC; a coal facility that is more than 50 years 

old recently replaced the boiler and condenser to improve efficiency, and will likely operate for 

many years. 

EPA agrees that it does not make sense to spend considerable time and resources on technologies 

that may only be used for a few years or less. However, EPA concluded that the 316(b) BTA 

standards should not build in an unintended incentive for facilities to delay closure because they 

may obtain an exemption based on planned retirement. Considering the long lead time to plan, 

design, and construct the most effective entrainment technology, closed-cycle cooling systems 

such as wet cooling towers, EPA determined that the Director should have the latitude to 

consider the remaining useful plant life in establishing entrainment requirements for a facility. 

The remaining useful plant life, along with other site-specific information, will affect the 

entrainment reduction of closed-cycle cooling at a facility. For example, retrofitting to a closedcycle system at a facility that is scheduled to close in three years will not result in much 

entrainment reduction as compared to retrofitting to closed-cycle at a facility that will continue to 

operate for 20 years. 

Riverkeeper stated that industry has historically argued that facilities with little remaining useful 

life should be exempt from regulation because the costs of a retrofit to such a facility may not 

justify the benefits. They commented that remaining useful life is not quantifiable, certain, 

binding or relevant unless a facility owner has committed to a specific closure date and suggest a 

5-year timeframe. EPA agrees that facilities requesting exemptions related to planned retirements 

should commit to a specific date. EPA has included a provision in the final rule waiving certain 

permit application requirements for existing facilities that plan to retire the facility before the 

current permit expires. In addition, if the owner or operator of an existing facility plans to retire 

the facility after the current permit expires but within one permit cycle, then the Director may 

waive many of the permit study requirements pending a signed certification statement from the 

owner or operator of the facility specifying the last operating date of the facility. EPA notes that 

the entrainment requirements are established on a site-specific basis by the discretion of the 

Director who would take the issue of planned retirements into consideration and should be 

capable of assessing the veracity of such claims. 

Essay 19 194 
                                                            

Part of EPA’s rationale for reduced requirements where a facility has little remaining useful life 

is the timeline in which full compliance will be achieved by facilities subject to this rule. Full 

studies and analysis as part of the initial permit application, including IM requirements and 

Entrainment Characterization Study, are expected to take approximately 3 years to complete, and 

will generally take 2 years to complete in subsequent permit applications. Since permits are 

generally issued on 5-year cycles, in any given year some 20 percent of facilities are expected to 

apply for a permit. In the example when a permit application is made immediately after the final 

rule effective date, where required data is collected as soon as practical, where there are minimal 

additional technology requirements, and where the permit is issued as soon as practical, EPA 

estimates it would take a minimum of 3 years to achieve full compliance. On the other extreme, 

where a permit application is submitted closer to 5 years after the effective date of the rule, data 

is collected prior to the permit application due date,30 and significant technology upgrades are 

anticipated (such as closed-cycle or a relocated intake at a baseload power generating facility or 

a complex manufacturing facility), EPA expects full compliance could take longer than 14 years. 

See Section VIII of preamble for further discussion of implementation. In view of the range in 

time that may be required for full compliance, EPA expects that full compliance with the 

impingement mortality and entrainment BTA requirements will, in most cases, take at least 6 

years. As noted above a permit is typically issued for 5 years. In other words, after consideration 

of the permit application study requirements, the permit cycle, the entrainment determination by 

the Director, and the facility’s choice of compliance alternative for IM that harmonizes with this 

entrainment determination, EPA does not expect that a permit with entrainment determinations 

can be fully implemented by the facility during the first permit cycle (i.e., the first 5 years) after 

this rule’s effective date. As discussed in the preamble, for impingement requirements the 

compliance date is determined by the permit schedule and selected compliance alternative – a 

schedule which again is subject to some discretion by the Director in order to harmonize the IM 

requirements with any required entrainment controls. Regarding the concern that units may avoid 

compliance through delay of planned retirements, EPA notes that the Director has the discretion 

to require interim entrainment controls at 40 CFR 125.94(h). 

Riverkeeper also noted that some facilities may claim that the remaining useful life (of their 

cooling system or compliance technology) may be too long in that they have not yet been able to 

recoup original construction costs and therefore should be exempt from technology upgrades. 

They were concerned that EPA’s focus on remaining useful life would allow permitting 

authorities to consider too long as well as too short remaining useful life in determining 

compliance requirements. EPA would like to make it clear that with respect to this issue, EPA is 

only concerned with situations where the remaining useful life of the entire unit may be too brief 

to warrant a substantial expenditure for compliance technology that would be useful for only a 

brief period. EPA notes the model facilities used for conducting the cost analysis are based on 

the technical questionnaire, and since the data therein is at least 10 years old, the technology in 

place reported in the technical questionnaire has also been installed for at least 10 years. 

Therefore, EPA disagrees that many facilities (if any at all) can reasonably claim compliance 

technology costs have not yet been recouped. To the extent a facility’s existing compliance 

technology has been installed since the technical questionnaire, and the technology can be used 

30 In this case EPA does not anticipate 3 additional years to collect data because the data gathering activities will 

have already been completed prior to the permit application; see 40 CFR 125.95 for the time frame for permit 

application requirements. 

Essay 19 195 
to meet the final rule requirements, EPA’s costs are overstated. To the extent the existing 

compliance technology is not useable to meet the final rule requirements, because EPA’s cost 

methodology incorporates the full compliance costs as discussed above, EPA disagrees that the 

costs of the rule are incomplete. Further, EPA’s economic analysis is based on the above 

assumptions of compliance costs, and EPA did not find these costs to be unaffordable; see the 

preamble and the EA. Other concerns regarding remaining useful life apply to the production 

unit, not the compliance technology, and would not be a consideration in situations where the life 

of the required compliance technology itself would not be brief. In situations where units are 

planned to be replaced/repowered and the compliance technology can be incorporated into the 

design of the replaced/repowered unit, the remaining useful life of the units to be 

replaced/repowered should not be a consideration in determining compliance requirements. 

Energy Reliability is Not a Dispositive Factor in EPA’s Rejection of Closed‐Cycle

Cooling as BTA

In the proposed rule EPA considered energy reliability as an important factor in its decision not 

to prescribe a single technology as the basis for a national BTA entrainment standard and 

received a number of comments concerning this issue. Most commenters agreed that energy 

reliability should be an important consideration. But some commented that variances could be 

granted on a site-specific basis and that EPA acknowledges that extending compliance time for 

power plants with potential energy reliability issues would likely resolve such problems. 

EPA performed a revised reliability analysis for the final rule and, consistent with the proposal, 

results indicated that there would be no significant reliability impacts associated with requiring 

closed-cycle cooling. EPA also observed findings from the market model analysis conducted 

using IPM that demonstrated that the options analyzed for the proposed rule will not have a 

significant adverse effect at a national or regional level. Because of these findings, EPA did not 

prepare a Statement of Energy Effects. For further details see the Economic Analysis for the 

Final Section 316(b) Existing Facilities Rule (EPA-821-R 13-004). Based upon this evaluation 

EPA concluded that even for the most stringent option there would not be any significant 

reduction in reliability of the national or regional electricity supply. Accordingly, while EPA 

considered this in evaluating options for the final rule, it was not a dispositive factor in its 

determination to reject closed-cycle cooling as BTA. EPA notes that to the extent that facilities 

believe this is a relevant consideration in the site-specific determination of BTA, they can 

provide such data to the Director and the Director may consider it. 

Other Factors

In addition to land availability, air emission, remaining useful life, and reliability discussed 

above, commenters cited a number of other factors that may affect the availability of closedcycle, the costs of controls or the environment. According to commenters, these factors affecting 

the availability of closed-cycle cooling in any specific setting may include: 

 A highly adverse cost to monetized benefit ratio; 

 At a number of facilities insurmountable piping difficulties may be encountered; 

Essay 19 196 
 Requirements for the redesigning and reconstruction of large portions of the facility, not 

just the intake structure; 

 Loss of beneficial aspects of the thermal effluent for manatees; 

 Increased water consumption; 

 In tidal areas use of non-saline alternative makeup sources could negatively impact future 

ground water availability; 

 Environmental impacts through the discharge of cooling tower blowdown (treatment 

chemicals, concentrated pollutants); 

 Increased safety hazard associated with bulk storage of treatment chemicals used for 

closed-cycle cooling; 

 Impacts of fogging and icing; 

 Human health effects from pathogens, endocrine disruptors and particulates; 

 Increase in noise impacts should be considered; 

 Aesthetics; 

 Challenges to obtaining appropriate Federal, State, and local permits (endangered 

species, CWA section 404, local building height and noise); 

 Saltwater drift; 

 Impacts associated with building the required transmission to accommodate new 

generation far from load centers; 

 Lost jobs at manufacturing facilities since costs cannot be passed along to customers; 

 Process upgrades at manufacturing facilities such as heat exchangers to account for 

warmer water would be required; 

 Loss of manufacturing production capacity due to warmer water; 

 Added cost and energy requirements for upgraded process refrigeration machines; 

 Blasting mandates at nuclear facilities; 

	 Existing nuclear power generation, and to a lesser but still important extent, gas-fired 

generation, offer specific environmental benefits-to electric-system function, air quality 

and climate change goals-not provided by other sources of baseload power production; 

 Premature or immediate facility closures; 

 Extended construction-related outages and permanently reduced output and their effects 

on reliability and affordability. 

These are important, but they are secondary considerations that do not change (nor are they 

dispositive with respect to) EPA’s determination of the BTA impingement mortality and 

entrainment standards and rejection of closed-cycle cooling as the sole technological basis for 

BTA. Because closed-cycle has already been rejected as BTA, EPA is not responding 

specifically to these items with regards to consideration of BTA and has not specifically 

Essay 19 197 
analyzed all of these considerations in terms of costs, benefits or impacts. EPA acknowledges 

that some of these may require consideration on a site-specific basis and may affect costs. Many 

of these considerations were considered in developing the compliance costs for the options 

evaluated (see Chapter 6 of the TDD). Given that any requirements for closed-cycle cooling will 

result, if appropriate, from a site-specific determination by the Director, many of the above listed 

considerations are identified in the various components of the required permit application 

studies. Facilities will have the opportunity to raise these issues in their permit application 

documents, subject to review by the interested public, and considered by the Director in making 

the determination for entrainment. 

Regulatory Options

Technology Basis

Riverkeeper commented that a BTA determination does not require that a technology be 

available everywhere and that EPA opted for a lowest common denominator strategy - setting no 

uniform entrainment standard, and basing the impingement standard on traveling screens because 

they are capable of being installed everywhere. Riverkeeper commented that “technologyforcing” standards like BTA must compel industry to meet ever more stringent limitations and 

therefore must be established with reference to the best performer in any industrial category. One 

commenter stated that to be BTA for the industries covered, a technology must be shown to be 

technologically “available” to all of the facilities in the industry category or subcategory. EPA 

does not agree that a technology must be available to all facilities, but agrees that is should be 

widely available for the industries covered. As explained above, EPA rejected some technologies 

as BTA because they are not widely available (e.g., only 15 percent of facilities would be able to 

comply with a low intake velocity compliance alternative). 

EPA disagrees that CWA section 316(b) compels ever more stringent standards. More broadly, 

EPA does not agree that the language of section 316(b) identifying four elements to which the 

standard may apply (i.e., CWIS location, design, construction and capacity), necessarily limits 

what factors EPA may consider in section 316(b) decision-making. Congress did not express a 

clear and unambiguous intent that 316(b) requirements must be expressed only as uniform 

national technology-based standards. For example, in considering below threshold structures 

under the new facility rule (Phase I) the Second Circuit upheld a case-by-case approach and 

stated that 316(b) “...does not compel the EPA to regulate either by one overarching regulation, 

or based on categories of sources ... or on a case-by-case basis...” Riverkeeper, Inc. v. USEPA, 

358 F. 3d 174, 203 (2nd Cir. 2004). The U.S. Supreme Court decision further supports EPA’s 

discretion to consider a variety of factors, but section 316(b) imposes no obligation on the 

agency to do so. Also see Essay 10 for more information. 

Riverkeeper commented that EPA did not establish a presumptive hierarchy of technologies that 

must be applied if available. They stated that for the impingement mortality standard, EPA 

selected widely available modified traveling screens as the basis for BTA even though there were 

more effective technologies available at many facilities. EPA agrees that there are more effective 

technologies than modified traveling screens (such as the 0.5 fps intake velocity), but disagrees 

that these technologies are widely available (for example, only approximately 15 percent of 

facilities can meet 0.5 fps intake velocity); therefore the technologies cannot form the basis for 

Essay 19 198 
BTA. Also, see Essays 16, 17, and 18. EPA disagrees that a presumptive hierarchy should be 

applied to the IM standards. EPA selected modified traveling screens as BTA for impingement 

because it is widely available, demonstrated, feasible, and affordable; the record shows that more 

than 70 percent of facilities already have some form of traveling screens. EPA concluded that 

other technologies were also capable of performing equal to or better than modified traveling 

screens (such as offshore velocity caps), and while these technologies are not widely available 

and thus should not be considered as the technology basis for BTA (for example, offshore 

velocity caps are available for about 1 percent of affected facilities), the final rule recognizes 

such technologies as compliance alternatives. 

Riverkeeper commented that EPA is compelled to establish entrainment controls based on 

closed-cycle and that EPA has no authority to establish impingement only controls. EPA 

disagrees. The 316(b) statute only requires minimization of adverse environmental impacts 

(AEI), not its elimination. As the Supreme Court has clearly recognized, Congress knows how to 

require elimination of a problem when it expects that result. Thus, the Clean Water Act provides, 

with respect to discharges, that the ultimate goal of the statute is the elimination of the discharge 

of pollutants and the prohibition of the discharge of toxic pollutants in toxic amounts. See section 

101(a) of the Clean Water Act. Minimization necessarily implies choice of the degree of 

minimization required. Congress has entrusted the Agency with discretion in this area as its 

decision-maker. EPA has decided that the BTA standard for entrainment should be a structured 

process that, on a site-specific basis, results in entrainment controls tailored to the conditions at 

the site and the individual facility. The final rule appropriately addresses both impingement and 

entrainment AEI. The Second Circuit observed that “[t] he Clean Water Act does not forbid the 

EPA from addressing certain environmental problems on a case-by-case basis where categorical 

regulation is not technologically feasible, or when it does not violate the statute’s language and is 

otherwise consistent with Congress’s overriding goal of improving the quality of the nation’s 

waters (internal citation omitted here).” Riverkeeper, Inc. v. USEPA, 358 F. 3d at 203. For 

additional discussion, see Section II and Section VI in the final preamble and Essay 10. 

Riverkeeper also commented that for entrainment there should be a rebuttable presumption that 

closed-cycle cooling is BTA for all facilities with provisions that allow the permittee to attempt 

to make a showing that demonstrates closed-cycle cooling is not a viable option. As explained 

above, based on a combination of three factors: land availability, air emissions, and remaining 

useful life, EPA concluded that closed-cycle cooling was not BTA for existing facilities, and 

therefore did not based standards on closed-cycle cooling. EPA considered the approach 

suggested by Riverkeeper to establish standards for entrainment based on closed-cycle cooling as 

BTA and to provide “off-ramps” for facilities that could demonstrate that closed-cycle cooling 

was not a viable option. For example, EPA attempted to determine criteria based on the data in 

its record that would enable it to define a threshold for determining land availability on a 

nationwide basis, but was unsuccessful. One analysis explored a threshold of approximately 160 

acres per GW (gigawatt) below which a facility could not feasibly install cooling towers. Based 

on acres and the footprint of the facility and its surroundings (primarily those sites for which 

EPA conducted site visits), EPA found such an approach did not accurately identify which 

facilities could feasibly install closed-cycle cooling. Commenters stated that EPA’s assessment 

of 160 acres per GW for cooling towers is too simplistic and that having a specific threshold is 

reasonable only if it is used as a trigger for further evaluation and that land availability should be 

determined on a case-by-case basis. EPA notes that the 160 acres per GW was simply an attempt 

Essay 19 199 
at identifying a threshold. Recognizing the limitations of such a threshold, EPA decided not to 

incorporate this threshold in the final rule. 

EPA’s decision not to establish closed-cycle cooling as BTA with “off ramps” is broader than its 

consideration of a land threshold. As explained above, after fully considering all comments and 

data, EPA finds closed-cycle cooling is not the “best technology available for minimizing 

adverse environmental impact” on a national basis. Because of a combination of concerns over 

land availability, air emissions, and remaining useful life of the facility, EPA has rejected closedcycle recirculating systems as the basis for national impingement and/or entrainment 

requirements. Nor is EPA able to identify a subcategory for which these concerns no longer 

apply, nor did commenters suggest one. Moreover, the complex interaction of all of these factors 

at individual sites does not lend itself to other regulatory options that would require closed-cycle 

recirculating systems with an “off ramp” if any of the factors were shown to result in 

unacceptable impacts because this would create a presumption for closed-cycle cooling rather 

than an equal balancing of all relevant factors. EPA decided not to put its thumb on the sitespecific scale by establishing any presumptive BTA entrainment outcome. EPA finds the 

entrainment standards framework in today’s final rule will provide a consistent, more efficient, 

and more effective approach than standards with an “off ramp.” 

With respect to one of the IM compliance alternatives, one commenter stated that an Entrainment 

Characterization Study should not be required for intakes that meet the less than 0.5 fps intake 

velocity impingement compliance alternative. EPA disagrees since compliance with the 

impingement standard only ensures reduction of impingement mortality. Juvenile fish have lower 

swim speeds and smaller energy reserves and therefore cannot escape from an intake with a 

velocity of 0.5 fps. Many entrainable organisms may be non-motile or slow swimmers; eggs, for 

example, have zero mobility and zero avoidance response capability, and most early life-stages 

of fish such as larvae have no skeletal structure and no avoidance response. 

One commenter stated that EPA should have considered a “no regulatory action” option. EPA 

did consider a BPJ rule. EPA disagrees that no action is appropriate in this case because there are 

technologies that are available, demonstrated, feasible, and affordable for all facilities, and EPA 

has found the costs of such controls are justified by the benefits. EPA found this rule to be 

necessary to minimize AEI based on the record, noting the mortality of hundreds of billions of 

aquatic organisms that are impinged and entrained at cooling water intakes that withdraw water 

from waters of the United States each year. See the preamble for further discussion of the need 

for this rule and for EPA’s rationale for selecting the regulatory option and rejecting others. 

One commenter was concerned that the proposed rigid IM performance standard and low 

velocity compliance alternative are based on a small number of intakes and does not consider the 

wide variety of existing technology in-place. EPA disagrees that the IM performance standard 

and the low velocity compliance alternative in the final rule are based on a small number of 

intakes. As noted above, traveling screens are already installed at 70 percent of all facilities. The 

12-month IM performance standard is calculated from data for 17 facilities located in a large 

geographic area stretching from Massachusetts to Florida and as far west as Minnesota and 

Nebraska. See Essay 16A. The 0.5fps velocity is based on the analysis of fish burst swim speeds, 

and is therefore based on the thousands of intake structures where such fish and shellfish may be 

located. EPA disagrees that the final IM standard is rigid and notes that the final rule IM 

Essay 19 200 
requirements take into consideration the wide variety of site-specific conditions and technologies 

in-place. Further, the final rule allows facilities to choose to comply on an intake basis or facility 

wide basis, and further allows facilities to select from seven impingement mortality compliance 

alternatives. 

Proposal Option 1

As explained above, after a careful review of the proposed options, additional data, and public 

comments on both the proposed rule and the two NODAs, EPA has opted to promulgate BTA 

standards for the final rule that are similar to that of Proposal Option 1. How the BTA standards 

vary from Proposal Option 1 and EPA’s rationale for selecting this option for the final rule are 

described in detail in Section VI of the final preamble. 

EPA received many comments concerning the proposed selection of Option 1. Many supported 

EPA’s selection because Option 1 would not require the specific flow reduction requirements 

based on closed-cycle cooling contained in Options 2 and 3. Others opposed Option 1 because it 

included specific impingement mortality requirements including a monthly and an annual 

standard. Others commented that EPA has failed to demonstrate that current impingement levels 

are causing AEI. One commenter noted that EPA justified Option 1 largely on the qualitative 

benefit of protecting threatened and endangered (T&E) species, and yet EPA admits that it is 

“unable to quantify effects on T&E populations from the Rule.” 

EPA disagrees with the assertion that existing impingement levels are not causing AEI. First, this 

assertion reflects the commenters’ opinion that AEI requires a population level impact; nothing 

in CWA section 316(b) states this requirement. EPA further notes this issue was addressed in 

Riverkeeper I, where the 2nd Circuit stated: 

“We think that the EPA’s focus on the number of organisms killed or injured by 

cooling water intake structures is eminently reasonable. See Final Rule, 66 Fed. 

Reg. at 65,262-65,292. As discussed above with respect to restoration measures, 

Congress rejected a regulatory approach that relies on water quality standards, 

which is essentially what UWAG urges here in focusing on fish populations and 

consequential environmental harm.” 

EPA used this same approach in Phase I, and this approach was continued without change in the 

Phase II and Phase III rulemakings. Commenters have not here provided any new data 

supporting their alternative approach to AEI. Also see Essay 16. 

Second, the record shows nearly a billion losses in fish and shellfish due to impingement alone. 

Even when baseline losses are normalized to an age-1 equivalent, the losses due to IM&E are in 

the billions. EPA concluded that national BTA requirements for impingement mortality 

reduction are warranted. EPA disagrees that Option 1 was largely justified on the qualitative 

benefits of protecting T&E species. Consideration of impacts on T&E was one of several factors 

considered in selecting Option 1. For detailed discussion see Section VI of the final preamble. 

EPA re-considered whether a monthly IM standard was necessary to achieve the full range of 

environmental improvements under this rule. The 12-month IM performance standard will 

Essay 19 201 
require a facility to actively evaluate performance during the 12-month period enabling the 

facility to optimize the technology to improve performance and counterbalance a result that does 

not meet the standard with a result that exceeds the minimum standard. If EPA had included a 

monthly average, it would have similarly needed to incorporate some form of allowance for 

exceedances. An allowance for exceedances provides no incentive for improved operations to 

avoid such exceedances. As part of this evaluation, EPA determined that the 12-month IM 

performance standard is sufficient to ensure performance consistent with best technology 

available. Further, the additional biological compliance monitoring for a monthly standard would 

not improve the overall technology performance, but would cause additional expense. For these 

reasons EPA is not promulgating the monthly average that was included in the proposal. EPA’s 

decision is consistent with effluent guidelines where compliance with the monthly average 

limitation is not required for facilities subject to a longer term limitation such as an average 

limitation (e.g., pulp and paper 40 CFR 430 Subpart B AOX limitations). For further response to 

comments on monthly and annual IM performance standards, see Essay 16A. 

Environmental organizations opposed the selection of Option 1 because, in their view, it did not 

include specific entrainment reduction control requirements but allowed entrainment reduction 

requirements to be established on a site-specific basis. Commenters indicated that EPA abdicated 

its responsibility to adopt effective standards for minimizing environmental impact from cooling 

water intake structures. Some commenters stated that it was illegal for EPA to select Option 1 

over Options 2 or 3 and indicated that closed-cycle cooling was technologically and 

economically feasible and that EPA should honor the science and should also presumptively 

identify closed-cycle cooling as BTA for existing facilities. A State agency suggested EPA 

should establish an impingement standard of 88 percent reduction in mortality and an 

entrainment standard of at least 70 percent reduction in mortality. 

As discussed above, in the final rule, EPA established an impingement mortality performance 

standard based on modified traveling screens (with a fish return) because the technology is 

widely available, demonstrated, and affordable. There are several other technologies that perform 

comparably or better than the BTA technology, that while not available widely and thus not 

BTA, are available for some facilities and these technologies are included in the final rule as 

compliance alternatives. Also as explained above, EPA did not establish a BTA entrainment 

standard based on the performance of closed-cycle technology. EPA concluded that there is no 

“best” performing technology that is widely available, demonstrated, and affordable. Further, 

EPA could not identify another technology with performance that is anywhere near the 

performance of closed-cycle cooling. See TDD Chapter 5. EPA notes the comment suggesting an 

entrainment standard of 70 percent did not provide the basis for such a standard. As discussed 

above, the final rule adopts a BTA entrainment standard that requires determination of specific 

entrainment reduction measures on a site-specific basis. The standard prescribes a structured 

process for determining such controls after required consideration of identified factors at 40 CFR 

125.98(f), as well as other factors to the extent that the applicant has submitted such information. 

Also as discussed above, EPA is not precluded from considering standards that requirement a 

site-specific determination. 

Essay 19 202 
EPA notes Riverkeeper I has already upheld EPA’s authority to establish site-specific 

requirements: 

“Section 316(b) merely directs the EPA to require every cooling water intake 

structure subject to regulation under section 306 (which below-threshold 

structures indisputably are) to reflect the “best technology available.” It does not 

compel the EPA to regulate either by one overarching regulation, or based on 

categories of sources (as does section 306), or on a case-by-case basis (which, 

incidentally, was the tack the EPA took in its first crack at regulations pursuant to 

section 316(b).” 

and 

“The Clean Water Act does not forbid the EPA from addressing certain 

environmental problems on a case-by case basis where categorical regulation is 

not technologically feasible, see Nat’l Wildlife Fed’n, 286 F.3d at 566-67 

(upholding the EPA’s decision to regulate color discharges on a case-by-case 

basis), or when it does not violate the statute’s language and is otherwise 

consistent with Congress’s overriding goal of improving the quality of the 

Nation’s waters, see Natural Res. Def. Counsel v. EPA, 859 F.2d 156, 201-02 

(D.C. Cir. 1988) (upholding the continued enforcement of best professional 

judgment permit limits established prior to the promulgation of categorical 

limitations). It is, of course, true that once the EPA promulgates applicable 

standards, regulation of those facilities subject to those standards on a best 

professional judgment basis must cease, Natural Res. Def. Counsel v. EPA, 859 

F.2d at 200, but where the EPA is justified in not regulating uniformly, we see no 

reason why the EPA should have to avoid all regulation. Given a choice between 

not regulating below threshold structures because of technical impracticalities and 

regulating them on a case-by-case basis, we think the EPA reasonably chose the 

latter course.” [underlined for emphasis] 

Some commenters, including state agencies, opposed Option 1 because of concern that the sitespecific determination of entrainment requirements would place additional burden on state 

agencies already experiencing backlogs in permitting efforts. One noted that EPA should provide 

comprehensive and clearly detailed guidance on the implementation of BPJ. EPA is aware of the 

burden that site-specific determinations for entrainment will place on state agencies. Where the 

final rule includes a site-specific determination, it reduces this state burden by requiring the 

facilities to conduct studies, analysis, and evaluations. In addition, the required peer review will 

significantly review state agency review burden. 

Other Options Considered for Today’s Final Regulation

EPA considered several other options in developing today’s rule, but ultimately rejected them. 

Essay 19 203 
Proposal	 	 	 Option 4

(Flexible Impingement Mortality Controls Similar to Final Rule at Existing Facilities with DIF 

of 50 mgd or more; BPJ Permits for Impingement Mortality and Entrainment at Existing 

Facilities with Design Intake Flow between 2 mgd and 50 mgd; Site-specific Entrainment 

Standard for Existing Facilities with DIF of 50 mgd or more; and Uniform Impingement 

Mortality and Entrainment Controls for All New Units at Existing Facilities Similar to Final 

Rule) 

At proposal, EPA’s preferred option was Option 1, which was the option closest to today’s final 

rule. At proposal, EPA also considered a variant of Option 1, called Option 4, which changed the 

impingement mortality requirements for facilities under 50 mgd from the performance standard 

in Option 1 to BTA as determined by best professional judgment. In the case of an existing 

facility below 50 mgd that added a new unit, the flow associated with the new unit would have 

been subject to the uniform entrainment requirements based on closed-cycle cooling. Finally, all 

existing facilities withdrawing more than 2 mgd of DIF would have been subject to entrainment 

requirements established on a site-specific basis, with the exception noted above for new units. 

EPA received many comments concerning the rejection of Option 4. Many commenters opposed 

EPA’s rejection of Option 4 indicating that Option 4 was consistent with EPA’s rationale used in 

developing the Phase II and Phase III rules stating that smaller intakes have lower impact and 

withdraw a smaller proportion of the source water. Some suggested that EPA failed to follow the 

directive provided to EPA by the Supreme Court Entergy decision and questioned whether EPA 

violated EO 13563 by selecting Option 1 over Option 4 failing to “tailor its regulations to impose 

the least burden on society....” Commenters indicated that the proposed Option 4 benefits are 

nearly the same as Option 1 but with a $56 Million lower cost. Some indicated that the cost 

burden will be disproportionate for smaller facilities with minimal incremental benefit and that 

the larger facilities are the most likely to be able to comply with the data collection, operational 

and monitoring requirements of the proposed rule. Other commenters supported EPA’s rejection 

of Option 4 stating that it provides little guidance to States for making BTA determinations and 

does not provide industry with a well-defined compliance standard for planning purposes. In 

particular, Riverkeeper stated that it is the least protective and most legally inadequate of all the 

options that EPA considered and should be given no further consideration. 

EPA ultimately rejected Proposal Option 4 because it found that the technologies on which the 

requirements of today’s final rule are based are available, feasible, demonstrated, and affordable 

for all regulated facilities on a national basis. Moreover, EPA’s analysis showed that the 

difference in the total costs for the two options was nominal. Additionally, EPA notes that many 

facilities with a DIF under 50 mgd already use closed-cycle cooling and would have minimal 

burden under the final rule. EPA’s cost analysis shows that 321 of 595 (54 percent) of facilities 

under 50 mgd have technologies would meet the final rule requirements, and 22 (4 percent) have 

no compliant technologies in place (weighted, based on detailed questionnaire responses, see the 

TDD for more details). The remaining facilities have one or more technologies in place and need 

minor upgrades or need to complete demonstration studies. Thus most facilities would have no 

difficulty complying with either the requirements EPA is establishing in today’s final rule or 

with those under Proposal Option 4. Proposal Option 4, by not distinguishing between those 

facilities under 50 mgd that have already minimized adverse environmental impacts from those 

that have not, masks the actions that would have to be taken by the latter group to comply with 

Essay 19 204 
today’s final rule. In addition, the flexibilities introduced in the June 11, 2012, NODA and 

included in today’s final rule apply to all facilities, rather than taking the Option 4 approach at 

proposal of providing for more Director discretion for only the smaller withdrawing facilities. 

EPA also concluded that the data collection activities required under the final rule will be more 

protective of threatened and endangered species because it provides information on a larger 

number of facilities than Proposal Option 4 for consideration by the Director in permitting 

decisions. Lastly, EPA acknowledges that Proposal Option 4 is more burdensome to permitting 

authorities than is the final rule, as it requires more site-specific decision-making. 

EPA disagrees with assertions that lower flow facilities are small facilities, that the rule would 

result in a disproportionate burden on small facilities, or that the costs are too high. For a 

discussion of why EPA appropriately subjected facilities between 2 and 50 mgd to the BTA 

standards promulgated today, see Essay 14 and Section VI of the final preamble. 

For the reasons explained above, EPA agrees with the commenters that supported rejection of 

Option 4 and notes that, in comparison, the selected Option 1 will reduce the burden on State 

agencies, provides a more clearly defined path to compliance for impingement reduction and will 

provide more protection for T&E species at smaller facility intakes. The proposed rule and final 

rule are not comparable to Phase II or Phase III, thus any arguments comparing them are not 

applicable. For example, Phase II (and III) would have established performance standards for 

entrainment for in-scope facilities, whereas today’s rule requires IM standards and site-specific 

determinations for E; see Essay 14 for more discussion. 

With respect to comments on reducing burden to society, the final rule is more cost effective 

than BPJ at any threshold suggested by commenters. The final rule requires studies as part of the 

permit application, and includes many pre-approved technologies and streamlined compliance 

alternatives for the IM standard that significant reducing biological monitoring for compliance. 

EPA expects that the vast majority of facilities subject to this rule will elect to comply with the 

IM standard via one of the seven compliance alternatives that does not require biological 

monitoring to demonstrate compliance with the numerical IM performance standard. EPA’s 

record shows that the compliance technology costs for the IM optimization study are less than 

standards determining via BPJ due to the expense of biological studies and monitoring associated 

with a BPJ determination. Based on the Phase II ICR (costs of $395k to $679k per facility for 

initial permit application, $7k annual reporting and monitoring), submission of basic 

characterization studies and permit application materials upon which site-specific impingement 

requirements would cost the facilities from $59.8 million to $99.3 million per year in aggregate 

($2012, for the 531 facilities with a DIF less than 50 mgd (i.e., Option 4)). Therefore the record 

shows that it is more cost-effective to set uniform standards for impingement than to utilize BPJ. 

(This statement does not hold true for entrainment.) 

With respect to comments on AEI, the record contains studies for more than 40 facilities with 

less than 50 mgd flows, showing low flow facilities do impinge and entrain fish and shellfish. 

The record also shows that low flow facilities can withdraw large portions of water from small 

waterbodies. Approximately 20 percent of facilities (41 facilities) below 50 mgd withdraw more 

than 5 percent of the mean annual flow of the fresh water river sources on which they are 

located. At least 14 percent of manufacturers below 50 mgd withdraw more than 5 percent of the 

mean MAF. Further, there are 17 facilities with a DIF less than 20 mgd and withdraw more than 

Essay 19 205 
5 percent MAF, and another 11 which withdraw from small unnamed or unknown source waters. 

Thus one fourth of the 116 facilities under 20 mgd exceed 5 percent MAF. Based on a review of 

the existing facility detailed questionnaire, EPA also found that facilities that withdraw less than 

50 mgd from a river or estuary and that are also small businesses are co-located with one or more 

facilities. At a minimum these small businesses in aggregate pose the cumulative impact of a 

higher percent of the source water being withdrawn; see TDD Chapter 5 for more information. 

After a careful review of the public comments on both the proposed rule and the two NODAs, 

EPA concluded that none of the issues raised by the commenters warrant a change in EPA’s 

decision to not select Option 4. See the Basis for the Final Regulation section of the preamble for 

further discussion and Essay 14. 

Regarding the comment that EPA violated EO 13563, EPA has assessed costs and benefits (C-B) 

for the final rule and has reasonably determined that the benefits of the rule justify the costs. 

EPA agrees that exclusion of nonuse benefits from C-B considerations is arbitrary. It is 

disingenuous for commenters to argue C-B rationales to support a threshold and simultaneously 

discount EPA’s efforts to fully monetize the benefits of this rule. For example, the exclusion of 

nonuse benefits from C-B consideration suggests that the nonuse benefits of large flow facilities 

may be different than small flow facilities. Further, cumulative impacts of facilities with DIF 

below 50 mgd are significant in most of the U.S. At least 54 percent of withdrawals by just those 

facilities with DIF below 50 mgd are cumulative withdrawals, i.e., there are withdrawals by more 

than one facility on the same river segment. EPA does not have the data to monetize benefits 

based on reduced cumulative impacts. For all of these reasons, while EPA has considered costs 

and benefits, a threshold selected exclusively on C-B grounds is unsupported by the record. See 

Sections VI and XI of the preamble for further discussion. 

One commenter, Georgia Pacific, stated that EPA has failed to account for certain state level 

trends – that future state-driven water conservation efforts could cause several of their smaller 

facilities (with design intake flows greater than 2 mgd but less than 50 mgd) that are currently 

exempt based on the 25 percent cooling water threshold to be subject to this existing facilities 

rule as a result of reducing overall water use and thereby increasing the percentage of cooling 

water used. The selection of Option 4, rather than Option 1, would minimize these unintended 

consequences. EPA notes that the commenter supports this assertion with an unsupported 

statement that “cooling water use as a percentage typically becomes greater as water is recycled 

at most manufacturing facilities.” EPA disagrees with this statement as it relates to the final rule 

definition of cooling water. The definition of cooling water in the final rule excludes cooling 

water that is used in a manufacturing process either before or after it is used for cooling. Thus, 

this water is considered as process water for the purposes of calculating the percentage of a 

facility’s intake flow. EPA included this reuse clause in the cooling water definition as an 

incentive for flow reduction through reuse of cooling water. Thus, the cited facilities need only 

include cooling water reuse in a similar proportion as the overall flow reduction in order to 

maintain their current status. EPA notes that the opposite (i.e., facilities may fall out of scope) 

may be just as likely, or even more likely to occur, since this clause allows facilities that 

currently fall within the scope of the final rule to no longer fall within the scope if they are able 

to reduce cooling water use to less than 25 percent through reuse. 

Essay 19 206 
Proposal	 	 	 	 	 Options 2 and 3

Proposal Option 2—Flexible Impingement Mortality Controls Similar to Final Rule at All 

Existing Facilities that Withdraw over 2 mgd DIF; Require Flow Reduction Commensurate with 

Closed-cycle Cooling by Facilities greater than 125 mgd DIF and Uniform Impingement 

Mortality and Entrainment Controls for All New Units at Existing Facilities. 

Proposal Option 3—Flexible Impingement Mortality Controls at All Existing Facilities that 

Withdraw over 2 mgd DIF; Require Flow Reduction Commensurate with Closed-Cycle Cooling 

at All Existing Facilities over 2 mgd DIF. 

Proposal Option 3 was, in many ways, the same as requiring closed-cycle cooling at all existing 

facilities. As described above, each of the three factors for rejecting closed-cycle cooling as BTA 

for entrainment would apply with equal force for Proposal Options 2 and 3. As a result, EPA has 

concluded Proposal Options 2 and 3, similarly, are not appropriate as BTA for entrainment. 

EPA received many comments concerning the Rejection of Options 2 and 3. Many commenters 

opposed EPA’s rejection of Options 2 and 3, indicating that the closed-cycle cooling requirement 

in Options 2 and 3: 

 Were consistent with the goals of the Clean Water Act; 

 Would increase air pollution by only a small amount; 

 Provide less of a burden on State agencies; 

 Are technologically and economically feasible; 

 Would provide far more robust protection for America’s waterways; 

 Would create jobs; 

 Have higher monetized benefits that EPA estimated. 

In particular, environmental organizations commented that closed-cycle cooling should be the 

presumptive standard and that the four factors identified in the proposal in support for rejecting 

closed-cycle cooling as BTA could be addressed by allowing the permittee to demonstrate 

closed-cycle cooling is not a viable option and that particular sites with difficulties can be 

addressed individually. They indicated that Option 3 is well-supported by the law and by 

scientific facts and that the EPA estimated costs of complying would be only $1.47 per 

household for electric generators even under Option 3, and that only 3.4 percent of facilities 

would experience even “moderate” cash flow impacts. They indicated that Option 3 would not 

cause electric reliability problems, would not increase electricity prices, and would not cause any 

significant adverse environmental effects. Riverkeeper commented that EPA overestimated 

closed-cycle costs and that the costs of retrofitting to closed-cycle cooling are minimal from both 

a microeconomic and a macroeconomic perspective. They note that at the company level, EPA 

estimated that, at the very most, 1.5 percent of existing power units would retire as a result of the 

compliance costs and consider this an overestimate since EPA assumed companies would 

assume costs rather than pass them on. They also note that the annualized total cost of Option 3 

at a 7 percent discount rate, the highest cost estimate in the analysis, is $4.86 billion, or 0.033 

percent (1/30 of one percent) of the $14 trillion U.S. GDP. 

Essay 19 207 
Many other commenters supported EPA’s decision not to select Options 2 and 3 because they 

did not believe closed-cycle cooling should be a BTA requirement. Many agreed with EPA 

citing one or more of the four factors identified in the proposal to support rejecting closed-cycle 

cooling as BTA (increased air emissions, land availability, remaining useful life, and energy 

reliability) as reasons for not selecting Options 2 and 3 along with: 

	 The costs far exceed benefits. Net benefits versus costs for Options 2 and 3 are far worse 

than Option 1 and costs are at least 10 times those of alternative technologies; 

	 Closed-cycle cooling is not feasible at many existing facilities; 

	 Closed-cycle cooling increases evaporative losses and chlorine use; 

	 These options do not allow for due consideration of site-specific technical feasibility; 

	 These options would result in an increase in early unit retirement; 

	 These options would result in a reduction in debris removal; 

	 EPA has failed to demonstrate that current impingement levels are causing AEI. 

As previously explained, EPA assessed a number of different technologies that reduce 

impingement mortality and entrainment as the possible basis for section 316(b) requirements. 

EPA concluded that closed-cycle recirculating systems (based on wet cooling towers) are the 

most effective technology for reducing impingement mortality and entrainment. EPA disagrees 

that costs for retrofitting closed-cycle at existing facilities are minimal. Total costs for power 

plants of $5 billion are almost 4 percent of total electricity sector revenues of $126 billion – by 

any measure a not insignificant amount. Therefore, EPA did look at costs and the other 

considerations cited above by Riverkeeper in EPA’s deciding whether to reject options requiring 

closed-cycle cooling. EPA determined they were not dispositive. 

As explained above, EPA has decided not to establish a performance standard for impingement 

and/or entrainment based on closed-cycle recirculating systems for existing facilities. As 

described previously, each of the three factors for rejecting closed-cycle cooling as BTA for 

entrainment would also apply in the case of Proposal Option 2 or 3, despite the smaller number 

of facilities that would be subject to a requirement to retrofit. The technology basis for 

entrainment controls for facilities above the threshold under this option would have been wet 

cooling systems. The constraints discussed above that are associated with retrofitting a large 

portion of the universe of affected facilities led EPA to conclude that requiring closed-cycle 

cooling on a uniform basis scale was not appropriate for a national regulation. 

EPA notes that it proposed multiple options that included closed-cycle, and solicited comment on 

all aspects of closed-cycle cooling. After fully considering all comments and data, EPA still finds 

closed-cycle cooling is not the “best technology available for minimizing adverse environmental 

impact” required on a national basis. Because of a combination of concerns over land 

availability, air emissions, and remaining useful life of the facility, EPA has rejected closedcycle recirculating systems as the basis for national impingement and/or entrainment controls. 

Nor is EPA able to identify a subcategory for which these concerns no longer apply. 

Essay 19 208 
After a careful review of the public comments submitted in response to both the proposed rule 

and the two NODAs, EPA concluded that the issues supporting the selection of Option 2 or 3 

raised by the commenters did not warrant a change in EPA’s decision to not select Options 2 or 

3. See the Section VI of the preamble for further discussion regarding this decision. Additional 

discussion is provided above regarding comments concerning the specific factors for supporting 

site-specific entrainment and rejecting a uniform standard based on closed-cycle. 

Regarding the 125 mgd threshold for Option 2, Riverkeeper commented that EPA should keep 

DIF as the measurement because DIF puts fewer burdens on States and because the actual intake 

flow (AIF) may change over time. They were concerned that once the NPDES permit 

determination is set, an increase of the AIF in the future may not be reassessed for years due to 

permit backlogs. See proposed rule at 76 FR 22192 and 22195, as well as the final preamble for 

further discussion of AIF and DIF. EPA has not selected Option 2 for the final rule, so specific 

comments regarding use of a threshold regarding AIF or DIF with respect to Proposed Option 2 

are not relevant to the final rule. The final rule applies to existing facilities with a DIF greater 

than 2 mgd. In addition, existing facilities with AIF greater than 125 mgd have additional 

information submittal requirements. 

For the final rule, EPA also considered some variations to the proposed Options in response to 

comments. 

Proposal	 	 	 	 Option 4 Variant

EPA also considered and rejected a variant of Proposal Option 4 for the same reasons Proposal 

Option 4 was rejected. As compared to Proposal Option 4, the variant does not include the 

impingement mortality flexibilities, but instead adopts the 50 mgd threshold to determine those 

facilities for which the Director has discretion in determining BTA. EPA analyzed this option to 

directly compare the effects of introducing flexibilities associated with the IM compliance 

alternatives at all facilities (as the final rule does) to the effects of introducing greater Director 

discretion for a subset of facilities, via BPJ permitting (as the Proposal Option 4 variant does). 

The preferred option at proposal, Option 1, was estimated to be more costly than Option 4 

(Option 1 was estimated to cost $384 annually as compared with $327 million annually for 

Option 4). The final rule is estimated to cost $275 million annually in comparison with an 

estimated cost of $290 million annually for the Proposal Option 4 variant. Thus, EPA found that 

the approach of introducing IM flexibilities at all facilities was both more effective at reducing 

costs to society and more readily justified as best technology available, compared to the 

approach of introducing greater Director discretion for only a subset of facilities (below 50 mgd). 

Hence, EPA rejected the Proposal Option 4 variant, and the approach of introducing greater 

Director discretion for only a subset of facilities (below 50 mgd). 

Proposal	 	 	 	 Option 2 Variant

EPA also considered a variation of Proposal Option 2 that would have used 125 mgd AIF rather 

than 125 mgd DIF as the threshold. However, as described above, EPA rejected Proposal Option 

2 and, for the same reasons, rejected this variant of Option 2. 

Essay 19 209 
Site‐Specific	 	 	 Approach to Addressing Impingement

Many commenters (primarily from manufacturing facilities) commented that EPA should adopt a 

site-specific approach to addressing impingement mortality, similar to that employed for 

entrainment. As a result, EPA also considered an approach that would have established both 

impingement mortality and entrainment requirements fully on a site-specific basis taking into 

account for the particular facility, among other factors, those previously described as pertinent to 

EPA’s 316(b) BTA determination. EPA rejected a fully site-specific approach for impingement 

controls principally because technologies for impingement mortality are available, feasible, 

demonstrated, and affordable for facilities nationally. Because technologies are available, a fully 

site-specific approach would place unnecessary burden on State permitting resources. Moreover, 

the final impingement mortality standard includes several alternatives that allow site-specific 

demonstration that a particular technology performs at a level representing the best technology 

available for the site. EPA is instead promulgating a modified version of the proposed rule, 

adding several elements of flexibility, and thus directly addressing many of the concerns raised 

by these commenters. Also see Essays 10 and 16. 

Consideration of Costs and Benefits on a Site‐specific Basis in Establishing

Entrainment Mortality Controls, Including a Cost‐Cost Test

Commenters indicated that the rule should have a robust economic variance provision. In 

general, they argued that the inclusion of a cost-cost variance is necessary to avoid the irrational 

result of requiring a facility to install a technology where that facility has unique, site-specific 

characteristics that cause individual compliance costs to be many times greater than those 

compliance costs considered by EPA. They note that EPA’s conclusion that a specific cost-cost 

variance is not necessary because under the proposed rule the Director already would have the 

discretion to consider such factors does not apply to impingement requirements since there is no 

allowance for the Director to provide a variance from any of the impingement mortality 

requirements based on cost and benefits. They state that if EPA intends to include this flexibility, 

the regulatory language must be clarified. 

As discussed in the proposal, EPA found that the cost-cost test it had adopted in the Phase II rule 

would have proved difficult to implement in part because the Appendix to the Phase II rule 

discussing how to apply the test was prone to uncertainty and error. EPA notes that the Phase II 

rule included requirements for entrainment reductions, and the final Phase II rule was more 

costly than today’s rule even though it only addressed existing large flow electric generating 

facilities. While not required to do so, the final rule includes sufficient flexibility to allow 

facilities to avoid exceptional costs. EPA accomplished this by structuring the final rule to allow 

facilities to choose from multiple impingement mortality compliance alternatives presenting 

facilities with a range of different costs associated with each alternative. Thus, facilities are free 

to choose the lowest cost alternative. These include streamlined alternatives based on modified 

traveling screens or a system of technologies that are intended to result in reduced long-term 

costs by reducing future monitoring requirements. Also the final rule allows the Director to 

conclude based on site-specific data that impingement mortality at the site is de minimis and 

therefore no additional controls are warranted to meet the BTA impingement mortality standard. 

EPA has determined that the available compliance alternatives provide sufficient flexibility, and 

that the costs of such controls is sufficiently low such that no facility will experience an 

exceptional level of cost and need a cost variance. Commenters have not provided data to the 

Essay 19 210 
contrary. Indeed, EPA notes that detailed comments and data on EPA’s costs of the proposed IM 

requirements support the agency’s finding on this matter; see TDD Chapter 8 concerning costs 

and Chapter 12 for uncertainty analysis in costs. Therefore EPA has not included a cost test for 

IM in the final rule because of the flexible nature of the final impingement mortality standard 

(i.e., includes seven compliance alternatives), the significantly less cost of this rule (compared to 

Phase II), as well as the finding that IM is available, feasible, and achievable. 

Riverkeeper suggested the compliance costs to be considered in any cost-cost variance should 

include only capital expenditures, operation and maintenance, and energy penalty, not 

speculative, indirect add-on costs. EPA notes that the final rule does not include a specific costcost variance and that the Director’s evaluation of site-specific entrainment requirements may 

include consideration of many factors including costs. EPA recognizes that the Director is in the 

best position to evaluate what entrainment controls are appropriate at a particular site taking into 

account the costs cited by the facility and other factors identified at 40 CFR 125.98(f)(2). 

Subcategorization

Capacity Utilization Rating As a Basis for Different Standards, Peaking Units,

Seasonal Operation and Other Related Comments

EPA received a number of comments concerning capacity utilization rates (CUR) and the 

applicability of requirements to peaking units and intermittently operating facilities. Some 

argued that facilities with low capacity utilization rates should be subject to the same limitations 

on entrainment, entrapment, and impingement as other facilities. Most argued that low CUR 

facilities should be exempt from impingement and/or entrainment requirements with possible 

exceptions for those that use disproportional amounts of water or operate during periods of peak 

biological activity. They note that as EPA explained in the preamble to the Phase II rule, 

imposing entrainment controls on facilities with capacity utilization rates at or below 15 percent 

is not economically practicable and that the impacts of such facilities is small. Various 

definitions for low CUR were suggested (e.g., 10 percent, 20 percent, 1,500 hrs per year, 

percentage set equal to the BTA mortality rates). Another stated it is unclear as to what 

flexibility NPDES states have in addressing old power plants that are rarely, if ever run. They 

questioned whether EPA considered alternative permitting and/or implementation procedures to 

address the older facilities that are mothballed, placed on cold standby, or maintained in various 

other states of operational readiness but are rarely, if ever, placed into operation. An industrial 

stakeholder stated that the factors EPA used to justify eliminating consideration of low CUR in 

determining requirements don’t necessarily apply to manufacturing intakes with a low frequency 

of use such as for aircraft engine testing and research and development activities. In order to 

account for such operations, they suggested EPA should exempt CWISs used for these activities 

or use intake flow capacity utilization to determine which CWIS at manufacturing facilities are 

used often enough to justify the costs of any further regulation. 

The final rule, in contrast to Phase II, does not establish a single uniform technology-based 

requirement for entrainment reductions, but rather entrainment determinations will be made on a 

site-specific basis. Further, the final rule includes seven alternatives for achieving the 

impingement mortality standard. To this extent, therefore, the CUR provision in the Phase II rule 

is not particularly pertinent to this final rule. EPA disagrees that, as a categorical matter, low 

Essay 19 211 
CUR facilities have minimal impact. EPA found that low CUR facilities are generally peaking 

plants that operate at full capacity for portions of days during a few months or less. Further, EPA 

found that some sites continue to withdraw water through their cooling water intake structure 

even when no power is being generated. With respect to entrainment, if that period of cooling 

water intake operation corresponds with times when spawning is occurring, those facilities could 

have significant entrainment. In contrast to Phase II which included minimum entrainment 

reductions, today’s BTA standards for entrainment and impingement mortality are less costly 

and do not result in disproportionate economic impacts, even for low CUR units. Therefore, EPA 

has no record basis for and is not including an outright exemption for all low CUR facilities in 

the final rule. For the same reasons, EPA is not including an exemption for “infrequently” 

operated intakes at manufacturing facilities. 

EPA notes that with respect to today’s IM standard, all facilities have seven compliance 

alternatives. In particular, EPA notes that the lowest CUR units may indeed be operated at times 

where I and or E are minimal. Such facilities may be able to comply with the impingement 

mortality standard under 40 CFR 125.94(c)(6) with a system of technologies, such as flow 

reduction, location, and seasonal operation, demonstrated to achieve comparable impingement 

mortality reduction performance to that achieved by modified screens. Alternatively, under 40 

CFR 125.94(c)(11) a facility can demonstrate to the Director that impingement mortality at its 

site de minimis and consequently, no additional controls are warranted. 

However, EPA agrees there are valid reasons that the IM requirements should be considered on a 

site-specific basis for some infrequently used units, especially some very low CUR units and that 

the existing IM flexibilities may not account for such situations. Therefore, while the final rule 

applies to low CUR units, it includes a provision that enables the owner or operator of low CUR 

units to request the Director to establish BTA standards for IM for that unit’s cooling water 

intake structure which are less stringent that today’s final IM standards. After consideration of 

various approaches to regulating low CUR facilities, EPA concluded that only those intakes 

serving power generating units with a CUR of less than 8 percent may request less stringent 

impingement mortality controls as determined by the Director. In particular, CUR units serve 

critical energy reliability functions, such as during peak energy demands or during emergency 

events (such as a baseload unit going offline due to flooding). Therefore, EPA has determined 

that even with the numerous IM flexibilities, an additional provision specific to low CUR units 

was necessary to ensure energy reliability. See 40 CFR 125.94(c)(12). Also see the 

Implementation section of the preamble for further discussion. 

One commenter requests that State Directors be granted specific discretion to consider capacity 

utilization in establishing impingement and entrainment standards and monitoring requirements 

and if a capacity factor-based standard is unacceptable to EPA, an “off-ramp” based on AEI 

should be considered. EPA disagrees that AEI should be considered for impingement mortality 

standards except where for the most rare cases where the de minimis impingement can be 

demonstrated under 40 CFR 125.94(c)(11). As discussed above, EPA has determined that low 

CUR facilities will have little difficulty in complying with the BTA impingement mortality 

standard, given the broad range of compliance alternatives and the provision at 40 CFR 

125.94(c)(12). EPA notes that under the final rule entrainment requirements will be established 

in a site-specific proceeding that will take into account environmental impacts of the site. The 

permit application requires, among other data, information specific to operational status at 40 

Essay 19 212 
CFR 122.21(r)(8), as well as the baseline biological characterization at 40 CFR 122.21(r)(4). 

EPA expects that this will inform the Director, in establishing entrainment controls specific to 

low CUR facilities. 

One commenter suggested that an alternative approach would be to allow consideration of 

capacity utilization factor in the context of flow reduction and the calculation baseline to 

calculate reductions in impingement and entrainment. EPA disagrees with this suggested 

approach. EPA does not consider the relationship between the historical actual intake flow and 

the design intake flow as an indicator of flow reduction. For example, many baseload facilities 

operate at an AIF of approximately 50 percent of their DIF. These facilities should not get credit 

for the unused capacity of their intake structures. However, if a facility chooses to reduce 

operation as a flow reduction strategy, credit for the corresponding reduction in AIF may be 

incorporated in the system of technology compliance alternative. 

One commenter stated that low capacity facilities should not be required to complete the 

proposed Entrainment Characterization Study (ECS) because they do not operate frequently 

enough to meet the proposed permit application requirements. EPA disagrees. Any facility that 

withdraws more than 125 mgd must submit the ECS. Since the calculation of the AIF includes 

days of zero flow, facilities with low CUR should also have a low AIF and consequently, few 

such facilities, if any, would need to complete an ECS as part of their permit application. This 

125 mgd provision is also intended to address those situations where the facility is a low CUR 

facility, but continues to withdraw cooling water even though it is not producing electric power. 

A State agency commented that DIF should be used instead of AIF for determining entrainment 

requirements because using AIF gives an unfair advantage to peaking generators when assessing 

need for entrainment requirements. These peaking generators come on line and intake large 

quantities of water during their hottest and driest summer months, which only exacerbates the 

potential for environmental harm. EPA disagrees that DIF would be the better measure but 

understands that at certain sites, even facilities with lower AIF may have a substantial 

entrainment impact where high flow volume coincides with high biological densities or stress. 

As discussed above, this is why EPA has not categorically exempted peaking plants from the 

rule, and has not exempted such facilities from IM standards or entrainment requirements. 

Some commenters disagreed with EPA’s assertion that peaking unit operation may coincide with 

spawning periods. Other commenters noted that this may be true for the northeast but may not be 

true for other regions like Florida where peak spawning occurs in the spring and fall. EPA agrees 

that the timing between peaking unit operation and high biological activity will vary from region 

to region and site to site. However, as discussed above EPA does not have a record basis for 

exempting such units from requirements, and commenters here did not provide any such basis. 

As discussed above, EPA expects that the Director will take into consideration the operating 

schedule and seasonal biological data when developing actual site-specific entrainment 

requirements. 

One commenter expressed concern that low CUR plants will have difficulty collecting required 

characterization and monitoring data without forced operation. Facilities should not be required 

to operate to collect such data. Operating solely for the purpose of satisfying the permit 

application requirements would result in more entrainment/impingement, and unnecessary costs, 

Essay 19 213 
fuel use, and air emissions. EPA should consider amending the permit application and postinstallation verification monitoring requirements so that facilities can collect and submit 

impingement mortality and entrainment data collected when they otherwise would be operating 

and, if operations are sufficiently unpredictable, allow for waiver of requirements. EPA agrees 

that facilities should not be required to operate their cooling system in order to collect data. As 

noted above, the final rule does not require a facility to conduct biological compliance 

monitoring to demonstrate compliance with today’s IM standard. Rather, that approach is one of 

seven compliance alternatives. Facilities that choose to comply with the alternative that involves 

biological monitoring to demonstrate compliance with the numeric performance standards will 

not be required to operate the intake in order to collect data. Monitoring periods in which there 

was no operation will simply have no impingement data to submit. In other words, if the facility 

did not operate the intake structure in March, that facility did not impinge or entrain any 

organisms in March, and the facility data would appropriately reflect zero counts. Finally, 40 

CFR 125.96(f) provides that a facility may request less frequent monitoring under certain 

conditions. With respect to the permit application requirements, EPA notes that the required 

source water baseline biological characterization data is an evaluation of the biological 

community in the vicinity of the cooling water intake structure and does require the operation of 

the intake to be completed. EPA also notes that the ECS at 40 CFR 122.21(r)(9) specifies data 

gathering must be representative of entrainment at the intakes, thus nothing in the rule requires 

facilities to be operated to collect data. Similarly, the entrainment monitoring to support the 

facility’s calculations for the Entrainment Characterization Study must be collected during 

periods of representative operational flows for the cooling water intake structure. 

Commenters expressed concern that the installation of controls at low capacity units which can 

operate as independent profit centers is not cost effective as the capital cost cannot be recouped 

given the limited operation of the unit. They argue that requiring even the performance of 

advanced studies at these facilities, let alone the installation of technology, could potentially 

force the early retirement of these facilities and that the continued availability of low utilization 

units during times of peak demand significantly improves the reliability of the grid. If they are 

deemed to be “reliability, must run” facilities by the independent system operator charged with 

ensuring the stability of the electric system, then the costs of technologies or additional studies 

may be borne by the ratepayers. One suggested that, at the least, EPA should include a provision 

that allows the Director to avoid requiring studies for low CUR facilities in the event the facility 

operator is willing to enter into an agreement to retire the facility at the close of the eight-year 

compliance window. 

As explained above, EPA has found IM controls are available, feasible, and achievable. EPA 

disagrees that additional relief is warranted for low CUR units, as discussed above, based on the 

economic analysis of the less costly (compared to Phase II) rule. EPA has already included 

flexibilities for requirements to submit studies, and for facilities with low CUR units, as 

described above. EPA’s analyses demonstrate that the final rule is affordable, including for low 

CUR facilities. Regarding the comment requesting reduced requirements for low CUR units 

planning retirement see response under “Remaining Useful Plant Life Should be Considered in 

Establishing Compliance Requirements” section above. Regarding the costs of entrainment 

controls, EPA notes that entrainment requirements are based on site-specific considerations 

including costs. 

Essay 19 214 
Waterbody Type as A Basis For Different Standards

In general, industry disagreed with EPA’s decision to not consider proportional flow, waterbody 

type, or associated fish reproductive strategies as a basis for different requirements. They stated 

that EPA’s rationale for exempting facilities with intake flow less than 5 percent of waterbody 

flow under Phase II remains valid, that the impact of small intakes on large rivers are negligible 

and such adoption would also serve to reduce the administrative and implementation burden on 

State permitting agencies. Others suggested EPA should exempt entrainment requirements for 

greater than 125 mgd intakes where intake flow is less than 5 percent of waterbody flow such as 

on the Mississippi River. EPA disagrees that proportional flow should be a consideration in 

applying the BTA standards for the final rule. 

EPA notes that the Phase II rule exemption where withdrawals are less than 5 percent of the 

mean annual flow was only for freshwater rivers and streams, and further only applied to 

entrainment requirements. Here commenters are suggesting that such withdrawals should be 

outright exempted, including exempted from IM requirements. EPA disagrees; see Essay 14 for 

full discussion. Next, commenters assert that all such withdraws pose negligible impacts, but did 

not provide data supporting this position. As discussed above, AEI is defined as impingement 

and entrainment, and the studies in the record show that facilities of all sizes and on all 

waterbodies do impinge and entrain numerous organisms. EPA was upheld on this issue, and has 

neither proposed to change nor identified a record basis to change this definition. Further, as 

discussed above and in the preamble, EPA has identified significant potential for cumulative 

withdraws and cumulative impacts, such that exempting individual facilities would be 

inappropriate. In this final rule entrainment requirement are established on a site-specific basis, 

and as such, the need for entrainment requirements will be determined by the Director on a sitespecific basis, which may take impacts on the waterbody into consideration. Therefore, an 

exemption is neither appropriate nor necessary. 

Many industry stakeholder commenters wanted EPA to consider waterbody and or fish 

characteristics when establishing entrainment requirements noting that waterbody type is an 

important factor regarding AEI. The primary focus was on entrainment but a few mentioned both 

entrainment and impingement requirements. Suggested approaches include: exclusion based on 

predominant fish reproductive strategies; retaining the Phase II exclusion for lakes, reservoirs, 

and river/stream intakes with DIF less than 5 percent of waterbody flow; and exclusion of Great 

Lakes. In particular commenters focused on the differences between entrainment rates of eggs 

and fish larvae particularly between coastal versus inland freshwater bodies. Regarding 

reproductive strategies of the species present in the waterbody, commenters stated that it makes 

no sense for EPA to apply entrainment standards to fresh water systems where broadcast 

spawning species do not exist. Many commenters also questioned EPA’s argument and 

supporting documentation against subcategorizing intakes based on waterbody type. They 

particularly took issue with EPA’s assertion that data in the six graphs presented in DCN 10­

6701 and 6701A support EPA’s conclusion that entrainment concentration is similar in all 

waterbodies. Commenters were concerned as well with the lack of any explanation of the source 

for the underlying data, the methodology used to analyze the data, the unusual use of milligrams 

per liter units, the variation in sample sizes, or the use of different scales on the y-axis. They also 

argued that the six graphs in EPA’s documentation that show density of organisms in various 

waterbody types appear to clearly show that entrainment concentrations in marine and estuarine 

environments are much higher than entrainment concentrations in fresh waterbodies. 

Essay 19 215 
Riverkeeper supported EPA stating that there is a legal requirement for uniform national 

standards across all waters of the United States; that Congress intended that the best technologies 

available be used, and that technology-based standards not be relaxed based on assessments of 

local water quality, which in this context means considerations of the density or reproductive 

strategies of the aquatic populations in a particular waterbody; and that establishing different 

standards for different waterbodies based on their existing ability to support certain densities and 

populations would allow facilities to impact the remaining and badly stressed aquatic populations 

in waterbodies that have already been severely harmed by prior use as industrial dumping 

grounds. 

With respect to waterbody-based national standards for IM, as discussed above EPA disagrees. 

The IM performance standards are available, demonstrated, and feasible; further the final rule 

provides seven compliance alternatives. EPA disagrees with the industry stakeholder suggestions 

regarding the six graphs, again noting the above discussion that AEI is defined as impingement 

and entrainment. The graphs clearly show significant I and E densities in all waterbodies. EPA 

agrees that freshwater reproductive species are generally different than other waterbodies, but 

notes that this distinction has no bearing on which technologies can be used for IM, and further 

that waterbody type does not result in disparate performance levels of the technologies. EPA also 

notes that comments regarding the spawning habits of various species do not mean that larval 

stages and early life-stages of fish and shellfish will not be found in those waterbodies. Indeed, 

the graphs show that the range of densities of all life stages is similar in all waterbodies, and 

therefore establishing a waterbody-based standard may not provide adequate protection. Further, 

EPA found that there is no fundamental difference in technological performance or availability 

based on waterbody, and rejected these reasons as a basis for subcategorization. EPA notes that 

because the final rule requires entrainment to be determined on a site-specific basis, many of 

these comments will be addressed during such determinations. This may include consideration of 

physical and biological characteristics of the waterbody. This flexibility in the application of 

entrainment requirements addresses the commenter’s assertion by providing the opportunity to 

demonstrate to the Director that entrainment densities in the vicinity of the intake structure and 

the distribution of species in the waterbody do not warrant additional controls for entrainment. 

With respect to further comments about the Phase II rule exemption, EPA notes that further 

review of the available data in the proposed rule did not support EPA’s earlier conclusion; see 

preamble discussion regarding I and E, E survival, and E mortality. 

One commenter notes that the proposed rule may conflict with activities to restore the Great 

Lakes, adding that once-through cooling has a significant impact on the Great Lakes. EPA 

recognizes that there are many concurrent programs across the nation that are working to restore 

or improve water quality and commends these efforts. However, these efforts are independent of 

section 316(b) from a statutory perspective and EPA has developed a final rule that considers the 

appropriate factors established under the Clean Water Act and is supported by its analyses and 

record. EPA concluded that establishing subcategories for different waterbody types was not 

necessary or appropriate. To the extent the commenter does not support closed-cycle due to 

withdraw from the Great Lakes and subsequent evaporative losses, see discussion in Essay 17A. 

EPA received several comments suggesting other subcategorization approaches. Riverkeeper 

commented that EPA should subcategorize facilities according to the feasibility of control 

technologies and further suggested that if impact to small facilities was the concern, then setting 

Essay 19 216 
a higher threshold (e.g., 500 mgd) would be a better approach. EPA did not find that facility size 

nor impact to low flow facilities posed a rationale for subcategorization because the IM 

technologies are available, demonstrated, and feasible for facilities of all sizes and waterbodies; 

see EA. Further, low flow facilities do cause AEI; see preamble and Essay 14. Therefore, EPA 

disagrees with the comments and has decided to maintain the scope and applicability of the final 

rule at 2 mgd DIF. EPA explored the possibility of subcategorizing facilities based on feasibility 

of CCRS, and has rejected such an approach as discussed above. 

For a more detailed discussion of these and other factors considered for subcategorization by 

EPA see TDD Chapter 5. EPA considered subcategorization based on other control technologies 

as well as other attributes such as waterbody type, CUR, and flow but found that 

subcategorization based on these (or any other factors) was not necessary. EPA rejected 

subcategorization based on waterbody type and CUR and was unable to identify a suitable basis 

for subcategorization with respect to technology feasibility. EPA did consider subcategorization 

based on various flow thresholds and availability of space. For example, EPA considered a 

threshold of 50 mgd for Option 4 and requested comments on that approach; EPA rejected the 

Option 4 because technologies for IM are available, demonstrated, feasible, and affordable for all 

facilities. EPA also investigated other flow threshold values with the intent of reducing the total 

costs of the rule by reducing the number of facilities regulated while still capturing the majority 

of cooling water flow (for example, the 125 mgd threshold in Option 2). However, none of the 

thresholds considered resulted in subgroups with discernibly different attributes that would 

support subcategorization; see TDD Chapter 5. As described above, EPA also considered 

subcategorization based on available space but as discussed below was unable to identify a basis 

or metric that could provide a reasonably reliable assessment of feasibility of closed-cycle 

cooling. EPA notes that the 1976 rulemaking also attempted to consider available space. In light 

of the identified limitations on installation of closed-cycle recirculating systems in described 

circumstances, EPA concluded that providing the Director the discretion to consider multiple 

factors provides a much more reasonable approach to determining entrainment requirements. For 

the first time, EPA is including in the regulatory language specific requirements for studies, 

analysis, evaluation, and peer review of entrainment controls. This information will be submitted 

in the permit application, and will be considered by the Director when making a determination of 

BTA technology for entrainment. EPA notes that the commenter did not provide any suggestions 

regarding what specific basis EPA should have considered for subcategorizing based on 

technology feasibility beyond those EPA did investigate. 

Essay 19 217 
                                                            

 

Essay 20: New Units

Introduction

The Phase I 316(b) Rule requires closed-cycle cooling or an equivalent level of performance for 

newly constructed greenfield and stand-alone power generation and manufacturing facilities, 

which under certain circumstances may include new construction at existing facilities. In 

developing the existing facility final rule EPA observed that certain newly constructed units at 

existing facilities may share many of the same characteristics of Phase I new facilities and the 

same opportunity to incorporate updated design features, but are not new facilities as defined in 

the Phase I rule. Because of these similarities EPA decided that its BTA requirements for new 

units at existing facilities should be modeled after certain requirements applicable to a new 

facility under the Phase I Rule. 

Overall Response

In the proposal, EPA clearly defined those units that would be a “new unit” and requested 

comments on its definitions. New units were defined as additional units and did not include 

replacement or repowered units. After considering the public comments, for the final rule, EPA 

has changed the definition of new units to indicate that they are stand-alone units at existing 

facilities whose construction begins after the effective date of the rule, that are added to a facility 

for either the same general industrial purpose or for another purpose and that do not meet the 

definition of new facility (see, § 125.92). This provision distinguishes new units from new 

facilities, and further makes it clear that any new stand-alone unit at an existing facility would be 

subject to the new unit requirements. 

EPA’s rationale for adopting the same requirements for new units at existing facilities as the 

requirements for Phase I facilities is that, like Phase I facilities, these new unit construction 

projects present the ideal opportunity to design and construct the new unit’s cooling system in a 

manner that avoids many of the difficulties, additional expenses and operational disadvantages 

associated with retrofitting an existing unit to closed-cycle cooling. For example, the three 

factors that led EPA to reject closed-cycle cooling as BTA for existing units at existing facilities 

(land availability, increased air emissions, and remaining useful life) are far less relevant for new 

units at existing facilities than for retrofitting existing facilities. First, an existing facility may 

need additional land in order to accommodate new construction. EPA found in site visits that 

where land availability may pose a constraint, the construction of new units is often 

accomplished in phases that allow for the demolition of the old structures to make room for the 

new construction and that newly designed and constructed units can take advantage of innovative 

designs that use less space.31 Second, EPA rejected increased air emissions as a factor for 

rejecting closed-cycle as BTA for new units because the condensers will be optimized for closedcycle, reducing energy requirements, and high-efficiency cooling towers can be incorporated into 

the design of the new unit, potentially allowing for smaller cooling towers to be installed. Thus, 

31 Innovative locations can include locating towers over top of waterbodies such as discharge canal or the source 

water as well as locating dry cooling systems on rooftops. The innovative technologies are not limited to cooling 

tower technology. 

Essay 20 218 
                                                            

the turbine backpressure is eliminated and any associated energy penalty can be substantially 

reduced in a new unit. For more information, see the preamble and Chapters 6, 8, and 10 of the 

TDD. Further, the new unit is likely to be more efficient and emit less pollution than existing 

units, therefore net emissions are expected to decrease as new units replace older, less efficient 

units. Third, EPA rejected useful life as a factor for rejecting closed-cycle cooling because a new 

unit has the maximum opportunity to produce power or be used for production of manufactured 

goods for the longest time possible. Modifications and upgrades to maintain or replace an 

existing unit or to enable the unit to operate for a few years more are not part of the new unit 

definition. Therefore such upgrades would not result in the facility being considered a new unit, 

and there is no disincentive under the rule for needed upgrades to occur. EPA expects that most 

new unit projects that meet this definition will have a long useful life. 

New power producing units are almost always much more fuel efficient than existing units. This 

efficiency minimizes emissions and increases power output. For example, the average coal-fired 

plant had a heat rate of 10,498 BTU per kW-hr (EIA, 2012) corresponding to a fuel efficiency of 

32 percent. Modern coal-fired plants operate at 35-38 percent fuel efficiency, with some super 

critical32 plants approaching 42 percent. Combined cycle gas can achieve around 60 percent fuel 

efficiency. The more fuel efficient systems are also typically more energy efficient, resulting in 

lower cooling requirements. For all of these reasons, the three factors for rejecting closed-cycle 

as BTA for existing facilities would not generally apply in the case of new units. In consideration 

of each of these factors, EPA finds the record shows that closed-cycle is feasible, demonstrated, 

and available for new units at existing facilities. 

In setting BTA for new units, EPA also considered the costs of closed-cycle requirements for 

new units. EPA found that a significant number of new unit construction projects already employ 

closed-cycle. Therefore, the baseline analysis accounts for this trend. For example, many new 

units in the south and southwest are installing closed-cycle due to limitations in local water 

availability. See DCN 12-6673. Some recently built new units have not installed closed-cycle, 

and EPA has estimated costs for similarly constructed new units to install closed-cycle. When 

constructing a new unit, the costs of a CWIS large enough to accommodate once-through cooling 

are comparable to the capital costs of a facility with closed-cycle cooling. While differences in 

capital cost may or may not offset the energy requirements for operating closed-cycle cooling 

(i.e., cooling tower pumping costs) at a particular site, the total annual incremental costs are low. 

EPA found that these incremental costs do not pose a barrier to entry for new units; see the 

Economic Analysis (EA). 

The new unit requirements also apply to new units at manufacturing facilities. As discussed 

elsewhere, a majority of manufacturers use cooling water primarily or exclusively for power and 

steam generation; see Essay 14. In these instances, the new unit definition is appropriately 

applied to the manufacturing facility. EPA recognizes that, for other manufacturing facilities, it 

may be less clear, compared with power generation, what constitutes a “unit” and, further, it may 

require judgment to determine when construction of a new unit occurs at the existing 

manufacturing facility. EPA has addressed this issue, in part, by revising the definition of new 

unit. See Section I of the preamble for more discussion. 

32 Operating at 220 bar and 600 degree C superheat and reheat. 

Essay 20 219 
Finally, the EPA realizes that in a few instances, it is possible that installation of a new unit 

could result in an existing facility with a DIF of 2 mgd or less and thus not previously subject to 

this rule becoming subject to this rule’s existing facility requirements. The owner or operator of a 

new unit, as defined at § 125.92, at an existing facility not previously subject to existing facility 

cooling water intake structure requirements under 40 CFR Part 125 that increases the total 

capacity of the existing facility to more than 2 mgd DIF must submit the permit application 

information specified at § 122.21(r) at the time of the permit application for the new unit. In 

addition, the owner or operator of new units at existing facilities must submit to the Director the 

information required under paragraphs (r)(9), (10), (11), (12), and (13) at the time of the permit 

application for the new unit if the additional capacity will result in the existing facility 

withdrawing greater than 125 mgd AIF. The final rule definitions as well as the distinct section 

of permit application requirements for new units make it clear that, in such circumstances, a new 

unit is not the same as a new facility. 

Definition of New Unit

Many commenters expressed concern that the definition of new units provided in the proposed 

rule was unclear. Some were concerned that any modification to an existing unit might trigger 

new unit requirements. Commenters were particularly concerned that it is unclear how the 

concept of “new unit” would apply to a manufacturing facility. EPA solicited comments 

regarding the definition of new units in the proposal and considered issues raised in the public 

comments received in crafting the revised definition of new units for the final rule. For 

generating units, EPA has made it clear that only newly built, separate, stand-alone units that are 

added to a facility for either the same general industrial operation or another purpose meet the 

definition of a new unit. For power generators, the term “generating unit” is quite clear since 

there is only one product (electricity), the non-contact cooling water predominantly comes from 

one source, and the application of the term is well-understood in the industry. As discussed 

above, where manufacturers use cooling water primarily or exclusively for power generation, the 

same definition of new unit is equally applicable. EPA recognizes that the definition of what 

comprises a new unit at an existing manufacturing facility may be less clear than it would be for 

power generating facilities since manufacturing may include various subdivisions of process and 

product equipment groupings that could conceivably be deemed as a unit. For these reasons EPA 

has defined new unit to simply mean a new stand-alone unit. A new unit may include one or 

more distinct production lines that are added to increase product output and operate parallel to 

and independently of existing production equipment. A new unit does not include the 

replacement or rebuilding of one or more distinct production lines or distinct processes involving 

the replacement of the majority of the waste heat producing equipment that serves as sources of 

non-contact cooling water and the majority of the heat exchanging equipment that contributes 

heat to the non-contact cooling water. In many cases, the application of the term “new unit” will 

be quite clear while for a small handful of situations a site-specific determination may be 

necessary. The final rule clearly states it does not apply to “contact cooling water.” 

Many industrial stakeholders support the proposed new unit definition that excluded rebuilt, 

repowered, and replacement units at existing facilities, agreeing that they should be treated as 

existing facilities rather than as new units. Other commenters argued that replacements, 

repowerings, and rebuilt power plants should be required to meet standards based on closedcycle and that excluding repowered/rebuilt plants is a big loophole. One commenter also 

Essay 20 220 
                                                            

 

suggested that EPA should set a deadline by which all existing facilities must comply with the 

new source (new unit) standards in this rule to prevent environmentally destructive plants from 

remaining open longer than they otherwise would have absent the regulation. EPA agrees with 

the industrial stakeholders that all rebuilt, repowered, and replaced units at existing facilities 

should be exempt from the new unit requirements, for the reasons discussed below. EPA 

disagrees that all rebuilt, repowered, and replaced units should be defined as new units, for the 

reasons discussed below. After evaluating the public comments and considering the technical 

issues involved, EPA has made minor changes to the definition of new units. In the final rule 

new unit definition, EPA sought to distinguish those facility upgrades that constitute a 

modification or replacement of an existing unit from stand-alone projects where major 

construction will occur based on the extent to which these actions provide the opportunity for, 

and advantages of, employing closed-cycle cooling in a manner similar to those at Phase I 

facilities. Thus, EPA has specified that a new unit is a stand-alone unit, which is defined as a 

separate unit that is added to a facility for either the same general industrial operation or another 

purpose. EPA disagrees that a deadline is necessary to impose new unit requirements for all 

existing facilities. New unit requirements are not applicable to existing units at existing facilities 

for the reasons discussed in the preamble. In addition, new units could be added to existing 

facilities at different points in time, so a fixed deadline is impractical. Further, new unit 

requirements can vary and therefore any schedule is more effectively addressed in a permit. 

EPA agrees with commenter statements that the new unit requirements should not discourage or 

jeopardize the replacement of existing generating units with more efficient units that offer 

multiple benefits such as reducing air emissions per megawatt of electricity generated. EPA 

notes that an existing facility’s equipment will eventually need to be replaced and, over time, 

most facilities will be modernized using high efficiency units. EPA considered, and requested 

comment on, different ways to distinguish upgrades to an existing unit. After consideration of all 

comments, EPA concludes that avoiding disincentives to modernizing existing units is 

paramount. EPA further finds that the wide array of activities that could be considered as 

triggering new unit requirements do not always present the opportunity to design and construct 

the new unit’s cooling system in a manner that avoids many of the difficulties, additional 

expenses and operational disadvantages associated with retrofitting an existing unit to closedcycle cooling as discussed above. For example, a Type I uprate33 at a nuclear facility, and most 

Type II uprates34 do not involve extensive reconstruction, and therefore would involve a retrofit 

rather than a redesigned cooling water intake system. The final rule definition of new units does 

not discourage upgrade activities given its focus on new stand-alone units. EPA also agrees that 

high energy efficiency systems have multiple benefits such as reduced fuel consumption, 

33 Type I nuclear uprates, referred to as “measurement uncertainty recapture power uprates” are are achieved by 

implementing enhanced techniques for calculating reactor power. This involves the use of state-of-the-art feedwater 

flow measurement devices to more precisely measure feedwater flow, which is used to calculate reactor power. 

More precise measurements reduce the degree of uncertainty in the power level, which is used by analysts to predict 

the ability of the reactor to be safely shutdown under postulated accident conditions. See U.S. NRC, Types of Power 

Uprates, available at http://www.nrc.gov/reactors/operating/licensing/power-uprates/type-power.html. 34 Type II nuclear uprates, referred to as “stretch power uprates” are uprates within the design capacity of the plant. 

The actual value for percentage increase in power a plant can achieve and stay within the stretch power uprate 

category is plant-specific and depends on the operating margins included in the design of a particular plant. Stretch 

power uprates usually involve changes to instrumentation setpoints but do not involve major plant modifications.

See U.S. NRC, Types of Power Uprates, available at http://www.nrc.gov/reactors/operating/licensing/poweruprates/type-power.html. 

Essay 20 221 
reduced cooling water use and fewer air emissions and has sought to encourage rather than 

discourage such systems. EPA notes that rebuilt, repowered and replacement units will almost 

always be more efficient resulting in less cooling water use per unit of production. By requiring 

closed-cycle cooling in new stand-alone units, EPA is ensuring (along with the Phase I rule) that 

no new once-through cooling units or facilities will be built. For more information, see Section 

VI of the preamble. 

One commenter noted that at § 125.94(d)(1) it is not clear that the closed-cycle requirement only 

applies to the new unit. Further, the rule did not clarify how the rule applies to the existing intake 

if water for the new unit is to be withdrawn through it. A similar concern was expressed 

regarding the 90 percent comparable performance requirement in § 125.94(d)(2). One 

commenter noted that it is not clear if the standard at § 125.94(d)(1) applies to independent 

suppliers. EPA agrees the language was unclear since § 125.94(d)(1) referred to the “actual 

intake flow (AIF) at a new unit...” and has revised the requirement to read “design intake flow 

(DIF) for the new unit....” Note this final rule provision is now § 125.94(e), not § 125.94(d). 

These requirements apply only to the intake flow component associated with the new unit and 

not necessarily the source intake; see § 125.94(e)(1). The flow reduction requirement applies to 

the DIF requirement of the new unit and applies to independent suppliers in that they will be 

required to supply less water. The alternative comparable performance requirement may apply to 

an independent supplier in that such reductions may be achieved through changes in intake 

technologies employed. 

One commenter states that the definition of “replacement unit” should be clarified to mean 

replacement units of a specific size. Thus EPA would make it clear that a repowered or 

replacement unit of larger capacity than the unit it replaces would be a “replacement unit” and 

not a “new unit.” EPA’s definition of new unit applies to stand-alone units only and as discussed 

in the preamble does not include rebuilt, repowered or replaced units. Therefore, size designation 

is not necessary. 

Commenters are concerned that the rule is not clear about the applicability flow threshold for 

new units and suggested a de minimis flow exemption should be provided for new units. An 

example given was a 225,000 gpd new unit that should not be subject to the proposed rule 

requirements since it would not be covered under Phase I if built as a separate greenfield plant. 

Commenters suggested that EPA should at least exempt small facilities from an automatic 

closed-cycle cooling requirement, and instead allow them to engage in case-by-case analysis. 

EPA disagrees that any facility should be exempt from 316(b) requirements of this rule; see 

Essay 14 regarding scope and applicability. EPA further disagrees that low flow facilities should 

be exempt, see Essay 14 regarding cumulative impacts. In the final rule, the scope of the rule 

includes those facilities in which the total design intake flow is greater than 2 mgd, including 

both the existing and new unit cooling water withdraws (facilities with a design intake flow of 2 

mgd or less are subject to 316(b) requirements determined on a case-by-case, best professional 

judgment basis). EPA disagrees that there should be some sort of minimum incremental flow 

volume threshold for the new unit component. New units are a component of an existing facility 

and the relative size of a new unit does not change the factors that EPA evaluated in determining 

the new unit requirements. The addition of any new unit of any size and its cooling water 

requirements poses a new and additional withdraw from the source water, exasperating any 

cumulative impacts; see Essay 14. Also, setting a threshold at some level below 2 mgd could 

Essay 20 222 
allow facilities to break up new unit upgrades into components and stagger their implementation 

such that each remained under the threshold but in aggregate would clearly meet the scope of 

today’s rule. To the extent that a new unit results in the existing facility being subject to Subpart 

125 for the first time, see the above discussion regarding permit application requirements. 

One commenter stated that the “exclusively for cooling towers” and “only for replacing losses of 

cooling water” restrictions and the definition of “cooling pond” in § 125.92 are needlessly 

restrictive and could cause resources to be wasted on constructing new intakes with little or no 

benefit to fish. EPA no longer refers to cooling ponds or includes the cited restrictions in the 

final rule. The final rule provides clear guidance to the Director concerning the applicability and 

determination of closed-cycle cooling where water is withdrawn from impoundments that are 

also waters of the U.S. See the preamble for more discussion. 

BTA Requirements for New Units

Commenters argued that closed-cycle cooling should not be the presumptive BTA for new units 

at existing facilities and that the same standard should apply to both existing and new units. In 

other words, a case-by-case approach to entrainment should be applied to new units to take into 

account the same site-specific factors evaluated for existing units. Several commenters also 

noted that the rationale EPA used to conclude that new units should be treated as existing 

facilities under Phase II still apply today (i.e., factors such as energy requirements as well as site 

space limitations and site location characteristics that could affect visibility, highway and 

airport safety, noise, and salt drift make it inappropriate to subject new units at existing facilities 

to new facility requirements). 

EPA disagrees with the comments. As discussed in Essay 14, the Phase II and Phase III rules 

were remanded and subsequently revised in this rule based on EPA’s updated analysis. As 

discussed above and in the preamble, in contrast to existing units, new units, as more narrowly 

defined in today’s rule, have much greater flexibility in terms of cooling system design, 

construction scheduling, and other factors. These factors help minimize many of the negative 

aspects associated with closed-cycle cooling that prompted EPA for the final rule to conclude 

that it should adopt a site-specific approach for establishing BTA entrainment controls for 

existing facilities. EPA has discussed above how the factors of land availability, air emissions, 

and remaining useful life pose less of a barrier when considered in the context of new units. 

Other factors also support the final new unit provisions. For example, incremental downtime and 

issues of energy reliability, which can be associated with retrofitting to closed-cycle cooling, are 

avoided altogether at a new unit. In addition, when new units are added condensers can be 

configured for closed-cycle cooling, reducing energy requirements (by substantially reducing the 

turbine backpressure energy penalty and associated air emissions). High-efficiency cooling 

towers also can be designed as part of a new unit, allowing for smaller cooling towers. As a 

result of all of these factors, the capital costs for installing closed-cycle cooling at new units are 

lower than the capital costs for installing once-through cooling. (See DCN 10-6651.) EPA notes 

that one of the reasons that new units were treated as existing facilities in the Phase II preamble 

was that at the time EPA concluded that more stringent regulation might discourage or preclude 

projects that would improve energy efficiency. In the final rule, new units are defined as added, 

stand-alone units which are almost always much more fuel efficient than existing units so this 

consideration did not militate against adoption of the requirement for performance comparable to 

Essay 20 223 
closed-cycle systems for the new unit flows. With regard to several of the factors associated with 

closed-cycle cooling that EPA considered under Phase II in its rationale to define new units as 

existing facilities for purposes of that, now suspended, rule, EPA’s current analysis indicates 

that, where relevant, these factors can be sufficiently managed. The factors of visibility 

impairment, highway and airport safety issues, noise abatement issues, salt drift and corrosion 

problems are not universal for all facilities or all closed-cycle cooling technologies but rather 

will be of concern only at the portion of the facilities where the available tower locations are 

within proximity of certain receptors and where the technology under consideration involves use 

of a basic conventional mechanical draft cooling tower. Visibility and highway and airport safety 

issues are related to the visible plume of evaporative cooling tower which can generally be 

resolved through the use of readily available plume abatement technology (certain facilities 

might be able to use an alternative cooling technology such as dry cooling). Noise may need to 

be controlled in order to comply with noise ordinances of adjacent communities and can be 

minimized through the use of readily available noise abatement technologies. Similarly salt drift 

and corrosion problems associated with deposition of salt on nearby equipment can be 

minimized through the use of readily available high efficiency drift eliminators. Recent 

developments in salt drift elimination technology has resulted in drift rates as low as 0.0005 

percent (of circulating flow) compared to drift rates as high as 0.2 percent for a tower without 

drift eliminators. See TDD Chapter 10 for additional discussion. Each of these technology 

solutions is available and may add a certain amount of additional costs but EPA has concluded 

that these costs are not inordinate when part of a new construction. For a more detailed 

discussion see Section VI of the preamble. Regarding the rationale EPA used in Phase II, EPA 

sought to provide clarity between a new facility and an existing facility (69 FR 41579); EPA is 

continuing to do so, and today’s final rule does not affect the definition of new facility in the 

Phase I rule. EPA notes the Phase I rule treated the addition of a new unit for purposes of a 

different industrial operation as an existing facility only if it used an existing cooling water 

intake structure whose design intake flow was not increased. EPA further notes that there are a 

wide variety of repowering and uprate activities that an existing facility could undertake while 

still being regulated as an ‘‘existing facility’’ rather than a ‘‘new facility’’ (67 FR 17128). EPA 

has also maintained this distinction in today’s final rule; see Section I.J of the preamble on new 

units. 

Commenters noted that the 90 percent entrainment mortality option is more stringent than the 

Phase I rule. In particular, EPA requires a 90 percent reduction in “entrainment” in Phase I 

versus 90 percent reduction in “entrainment mortality” in the proposal noting that entrainment 

mortality is a subset of entrainment. EPA disagrees that the new unit requirements are more 

stringent than Phase I. In evaluating entrainment mortality, EPA assumes that entrainment 

mortality is equal to entrainment, unless entrainment survival is specifically demonstrated by the 

facility. See final rule at § 125.96(d)(3), which states that “Mortality after passing the cooling 

water intake structure must be counted as 100 percent mortality unless you have demonstrated to 

the approval of the Director that the mortality for each species is less than 100 percent.” The oneto-one relationship between flow reduction and entrainment reduction also applies to entrainment 

mortality reduction. EPA notes that even when they are not equal, limited data provided by 

commenters show they are still close. EPA’s analysis conservatively continues to presume the 

relationship is one-to-one. 

Essay 20 224 
One commenter also noted that by including the 94.9 percent and 97.5 percent flow reduction as 

standards in the definition of closed-cycle, that the new unit requirements were more stringent 

than Phase I. In Phase I, EPA stated that closed-cycle cooling reduced flow by a minimum of 70 

percent for saltwater systems. This value was adjusted in Phase II to a minimum of 72 percent 

flow reduction. Commenters then note that applying the Track II requirement for comparable 

performance of 90 percent results in a minimum flow reduction of 85 percent (90 percent of the 

94.9 percent flow reduction is 85 percent). The comments further assert that this is a change to 

the Phase I rule that EPA cannot lawfully make without giving fair notice or opportunity to 

comment. EPA disagrees. First, this definition would not in any way change the Phase I rule, as 

the proposed definition of closed-cycle would have only applied to existing facilities. EPA also 

notes that the low end of the range of 70 percent reduction cited in Phase I was given as an 

example of a worst case situation where site-specific water quality based discharge standards 

limit the chloride content in the blowdown to a maximum increase of 10 percent over 

background. This worst case scenario would limit the cycles of concentration of the cooling 

tower to 1.1. Both the Phase I and Phase II rulemaking records identify saltwater closed-cycle 

systems as clearly being capable of operating cooling towers at a cycle of concentration of 1.5 

(or greater). This 1.5 cycles of concentration is the level of performance equivalent to a 94.9 

percent flow reduction. However, this specific comment is no longer relevant since in the final 

rule EPA has changed the definition of closed-cycle so that a facility does not need to 

demonstrate that it achieved the cited values for cycles of concentration and the corresponding 

percent reduction in flow to establish that it is operating a closed-cycle recirculating system. 

Rather, as EPA has explained in the preamble to the final rule, achievement of the cited values 

for cycles of concentration and flow reductions are indications of a well-operated closed-cycle 

cooling system. CCRS is defined at § 125.92(c) to mean a system that reuses the water for 

cooling multiple times, and § 125.92(c)(1) makes it clear that a properly operated CCRS 

withdraws makeup water only to replenish losses due to blowdown, drift, and evaporation. See 

Essay 17A for further discussion. 

One commenter disagreed with EPA’s claim that “condensers can be configured for closedcycle” when designing a new unit, thus improving energy efficiency. The commenter indicated 

that, while this might be true for new condensing-steam turbine generators, it is irrelevant to the 

cooling water needs for many types of new units at manufacturing facilities, such as slag 

quenching, bearing cooling, or chillers. Thus, in the commenter’s view, EPA’s assumption that 

any energy penalty is negligible for such manufacturers is wrong. EPA disagrees, first by noting 

that the majority of cooling water intakes used at manufacturing facilities are for power 

production and, thus, function exactly like an electric generating facility. Second, one of the 

examples provided by the commenter (slag quenching) is contact cooling and, thus, would not be 

in scope of the rule. Third, bearing cooling does not involve an efficiency loss. The third 

example, chillers, can be designed to operate at a higher efficiency and thus exceed EPA’s 

performance for closed-cycle. In contrast to existing units, the energy penalty is negligible for 

new units for the reasons discussed above. Despite the failure of the commenter to supply 

evidence that, in fact, supported its position, EPA agrees that cooling water uses may be different 

at some manufacturing facilities and that the net effect on system efficiency of using a closedcycle system will vary. EPA maintains that it is reasonable to allow for the consideration of 

cycles of concentration in determining whether a cooling system is commensurate with closedcycle cooling, noting that in site visits EPA found the more complex manufacturing facilities 

would be challenged to calculate facility wide flow reductions. 

Essay 20 225 
One commenter noted that there is no equivalent alternative to closed-cycle, so an alternative 

compliance track does not exist. EPA disagrees. In the final rule, Under § 125.94 (e)(2) EPA has 

included a provision similar to Phase I, Track II where a facility can demonstrate compliance if 

they demonstrate entrainment reductions equivalent to 90 percent or greater of the reduction that 

could be achieved through closed-cycle. There are facilities where this level of performance is 

achievable without using closed-cycle cooling. Some facilities may be capable of achieving this 

BTA requirement through a combination of technologies which may include, but are not limited 

to, flow reduction, cooling water reuse, fine mesh screens, far offshore locations, and alternative 

intake location. EPA is aware of facilities that through a “systems of technologies” approach can 

combine one or more technologies to achieve an overall level of performance as required under § 

125.94 (e)(2). Specifically for manufacturers, EPA is aware that many facilities have conducted 

water audits and already implemented significant flow reduction and or water reuse practices; 

EPA expects manufacturers could demonstrate these reductions in flow as part of alternative § 

125.94(e)(2). Also, the new unit provision allows the Director to establish less stringent 

alternative requirements for a facility if compliance with the new unit standards would result in 

compliance costs wholly out of proportion or would result in significant adverse impacts on local 

air quality, water resources, or local energy markets. Thus, alternative compliance tracks do exist 

for new units. 

Commenters stated that proposed § 125.94(d)(5) (which states: “For cooling water flows 

specified in paragraph (d) of this section that are not subject to this standard, the Director may 

establish additional BTA standards for entrainment mortality on a case by case basis”) is 

unnecessary and unjustified. EPA disagrees. The final rule establishes national BTA standards 

for impingement and entrainment. To the extent uniform standards cannot be established for a 

subcategory, BTA standards must be established on a case-by-case basis. For example, contact 

cooling water at a pulp and paper facility is different than quench water at a steel mill, and EPA 

determined such cooling water was best addressed on a case-by-case basis. The withdrawal of 

any water for cooling may pose an adverse environmental impact, see Essay 14. As such, the rule 

allows the Director to establish BTA standards for entrainment mortality for this flow component 

on a case-by-case basis. EPA has retained this provision in the final rule for consideration of 

entrainment mortality requirements, similar to the provision for additional controls for IM as 

determined by the Director at § 125.94(c). 

One commenter stated that “If EPA nevertheless retains special requirements for new units, at a 

minimum, § 125.94(d)(4) should be revised so that it does not appear optional for the Director to 

establish alternative requirements even where the compliance costs are wholly out of proportion 

to the costs EPA considered or there would be significant adverse impacts on local air quality, 

significant adverse impacts on local water resources other than impingement or entrainment, or 

significant adverse impacts on local energy markets.” Within the new unit requirements, the final 

rule provides that the owner or operator of a facility must comply with any alternative 

requirements established by the Director pursuant to § 125.98(b)(7). The provisions in § 

125.98(b)(7) provide the Director with discretionary authority to establish alternative 

requirements when specified conditions are met, including a facility demonstrating that its 

compliance costs under § 125.94(e)(1) or (2) for each new unit would result in compliance costs 

wholly out of proportion to the costs EPA considered in establishing the requirements at issue. 

Essay 20 226 
                                                            

Where alternative requirements are not established a facility must meet § 125.94(e) for its new 

units. 

Projected Baseline Compliance

As part of estimating the costs associated with the new unit provisions, EPA projected what 

would have happened in the future in the absence of any rule or closed-cycle requirements for 

existing facility new units where only the current BPJ (or state program) approach to establishing 

entrainment mortality requirements are applied during the NPDES permitting process. This 

projection is referred to as baseline compliance and is defined as the degree35 to which new units 

would have been designed and constructed to utilize closed-cycle cooling or its equivalent. At 

proposal, EPA assumed a future baseline compliance rate of 50 percent based primarily on 

current overall compliance of existing units. Since proposal, EPA investigated baseline 

compliance further to determine the trend of closed-cycle cooling implementation over time. 

Based on new information concerning trends in the industry EPA concluded that baseline 

compliance would range between 75 percent and 90 percent. For a more detailed discussion, see 

DCN 12-6672 and Chapter 8 of the TDD. 

Many commenters have expressed concern regarding the imposition of closed-cycle 

requirements for new units at generating facilities. EPA’s analysis shows very few new power 

generating units are constructed in a given year, and further shows that many would have 

installed closed-cycle cooling in the baseline. Thus, while many commenters have expressed 

concern regarding the imposition of closed-cycle requirements for new units at generating 

facilities, the current trends and data indicate that in the future most facilities (between 75 

percent and 90 percent) will install closed-cycle cooling for their new units regardless of any 

final rule requirements. 

Implementation

Commenters were concerned with how compliance with the closed-cycle standard would be 

measured. One commenter indicated that if EPA intends that new units show that their makeup 

and blowdown flows are consistent with a closed-cycle cooling system, then it would be clearer 

to say so. Many were concerned that there is no baseline for comparison in a new unit and that 

using the actual intake flow (AIF) would be problematic since there may never be an actual 

baseline flow to measure. EPA agrees that using AIF would be problematic and has revised the 

new unit standard such that it is based on the design intake flow (DIF). EPA notes that the 

facility must reduce the design intake flow for the new unit, at a minimum, to a level 

commensurate with that which can be attained by the use of a closed-cycle recirculating system 

for the same level of cooling. The determination of closed-cycle cooling may be informed 

through calculation of the cycles of concentration or monitoring of flow. EPA notes that there is 

prior implementation experience determining compliance with the same standards (i.e., elements 

of Track II) at Phase I facilities since 2004, and EPA has modeled the BTA standards for new 

units after the Phase I rule language. 

35 In order to estimate compliance costs and impacts, EPA derived an estimate of the percent of new units that would 

be designed and constructed using closed-cycle cooling in the absence of any rule. 

Essay 20 227 
Commenters stated that the new unit requirements should at least be flexible enough to address 

sites where meeting the requirements is not technically feasible (e.g., land availability). 

Commenters also argued that the purchase of adjacent land should not be a consideration. Other 

comments suggested EPA should provide guidance, including a clearer definition of what it 

means for compliance costs to be “wholly out of proportion” stating that the proposed rule is 

currently quite vague concerning such waivers. EPA notes that the rule does not require facilities 

to consider purchase of adjacent land. As discussed previously, EPA finds closed-cycle is 

available, demonstrated, and feasible for new units at existing facilities in the nation as a whole. 

As discussed above, in Phase I, the final rule allows for the Director to establish less stringent 

alternative requirements for a facility if compliance with the standards would result in 

compliance costs wholly out of proportion to those EPA considered in establishing the Phase I 

requirements or would result in significant adverse impacts on local air quality, water resources, 

or local energy markets. In today’s final rule, EPA has included a similar provision providing the 

Director with the discretion to establish alternate requirements for each new unit if the 

requirements would result in compliance costs wholly out of proportion to the costs EPA 

considered in establishing the requirements at issue, or would result in significant adverse 

impacts on local air quality, significant adverse impacts on local water resources other than 

impingement or entrainment, or significant adverse impacts on local energy markets. Such 

determinations are necessarily made at the discretion of the Director and, therefore, EPA 

disagrees that further guidance on “wholly out of proportion” is necessary at this time. 

One commenter expressed concern that the new unit requirements do not appear to consider the 

circumstance where a new unit is constructed at an existing manufacturing facility where 

construction of the new unit does not require any modifications to the existing intake structure. 

EPA disagrees that the new unit requirements do not consider such circumstances. In evaluating 

new unit scenarios, EPA recognized that there are many circumstances where a new unit may 

have no impact on flow requirements or require no modifications to the intake structure. This is 

particularly true in the scenario where a new unit is installed and used in lieu of an existing unit 

with similar flow requirements. In the commenter’s example of using an existing intake structure 

to provide cooling water for a new unit, the existing intake clearly has the capacity to provide 

water for the new unit. Therefore, the final rule would simply require that the flow provided by 

the existing intake be a level of flow commensurate with CCRS. The closed-cycle requirement 

for new units is intended to require the use of BTA flow reduction technology which will have 

an impact on flow requirements reducing the intake flow with corresponding reductions in 

impingement mortality and entrainment. 

Commenters argued that the effective date of the new unit provisions should be delayed for a 

reasonable period of time after the final rule is issued since the proposed rule does not adequately 

provide for existing projects already well advanced in the planning, design and permitting 

process. EPA acknowledges that at promulgation, new units whose construction begins after the 

effective date of the rule must comply with closed-cycle requirements. EPA concluded that there 

will be few, if any units in the advance planning stages that would likely be adversely affected by 

this provision for the following reasons. As explained above in the discussion of “baseline,” EPA 

has determined that most new units will already include closed-cycle cooling. EPA, however, 

does acknowledge those in which construction begins soon after this date will have already 

undergone some level of expense and effort in planning, design, and permitting. The potential 

added expense of project delay and redesign could apply to those units with construction start 

Essay 20 228 
dates soon after the effective date of the rule and will diminish as time passes post-promulgation 

of the rule. Compared to the cost of the new unit, EPA does not find that the incremental cost of 

project redesign poses such a significant hardship as to discourage addition of units. Further, as 

discussed above, the Director may establish alternative requirements where the compliance costs 

are wholly out of proportion to the costs EPA considered or there would be significant adverse 

impacts on local air quality, significant adverse impacts on local water resources other than 

impingement or entrainment, or significant adverse impacts on local energy markets. 

Notice and Comment

Some commenters stated that “The Proposed Rule introduces a new concept for EPA regulation 

of cooling water intake structures: mandatory requirements for “new units at existing facilities,” 

which are modeled on requirements for entirely new facilities. EPA has not justified this 

departure from prior determinations, and the provisions of the Proposed Rule intended to 

implement the “new unit” concept are confused and should be deleted. EPA would need to repropose “new unit” requirements if it wants to continue with this initiative.” The commenter 

argued that it is impossible to determine what the proposed rules would require of facilities that 

install new units, therefore the commenter has not been provided with a meaningful opportunity 

to comment on this aspect of the proposed rule. 

EPA disagrees that, in adopting the new unit provisions, EPA has changed anything in the Phase 

I rule; nor did it propose any changes to the Phase I rule. The new unit provision only applies to 

existing facilities under Subpart J. Only a new facility, as defined in the Phase I rule found under 

Subpart I at 40 CFR 125 is subject to Phase I requirements. The definition of “existing facility” 

under Subpart I at § 125.83 makes it clear that a facility cannot be both a Phase I new facility and 

an existing facility at the same time, and EPA did not propose to change the Phase I rule. 

EPA disagrees that the public has not had a meaningful opportunity to comment on this aspect of 

the proposed rule. Not only did EPA take notice and comment on the definition of new unit, EPA 

specifically proposed that new units would be subject to a requirement based on closed-cycle 

cooling. EPA solicited comment on the general concept of new unit, and also specifically 

requested comments on the new unit provision in section XI.22. This includes specifically 

requesting public comments regarding the clarity of the definition of new unit and whether or not 

this definition should be expanded to include other units such as those that are repowered or 

rebuilt, or whether new unit provision should be deleted (see 76 FR 22275). EPA received 27 

comments regarding the new unit provision, suggesting that other commenters responded to 

EPA’s request for comment. EPA also requested comment on the number of new units and the 

amount of new capacity construction projected but received no specific comments related to this 

issue. Therefore, based on the numerous references to the new unit provisions in the preamble, 

the proposed regulation text, and the many comments received on the issue, the question of how 

to define new units and what the requirements for new units should be was clearly “on the table” 

and the final rule reflects a logical outgrowth from the proposal and the comments it 

generated. See American Coke and Coal Chemical Inst. v. EPA, 452 F.3d 390, 398-99 (D.C. Cir. 

2006). “‘An agency satisfies the notice requirement, and need not conduct a further round of 

public comment, as long as its final rule is a ‘logical outgrowth’ of the rule it originally 

proposed.’ Northeast Md. Waste Disposal Auth. v.EPA, 358 F.3d 936, 951–52 (D.C.Cir.2004). If 

interested parties ‘should have anticipated’ that the change was possible, and thus reasonably 

Essay 20 229 
should have filed their comments on the subject during the notice-and-comment period, then the 

rule is deemed to constitute a logical outgrowth of the proposed rule. See City of Waukesha 

v.EPA, 320 F.3d 228, 245 (D.C.Cir.2003); see also Envtl. Integrity Project v.EPA, 425 F.3d 992, 

996 (D.C.Cir.2005); First Am. Discount Corp., 222 F.3d 1008, 1015 (D.C.Cir.2000); Nat’l 

Mining Ass’n v. Mine Safety & Health Admin., 116 F.3d 520, 531 (D.C.Cir.1997). A petitioner 

must demonstrate that the agency’s violation of the APA’s notice and comment procedures has 

resulted in ‘prejudice,’ 5 U.S.C. § 706(2). See generally Chamber of Commerce of the United 

States v. SEC, 443 F.3d 890, 904 (D.C.Cir.2006). 

Essay 20 230 
Essay 21: Development of Compliance Costs

Introduction

Section IX of the preamble provides an overall description of the basis and methodology used to 

derive the compliance costs. A more detailed description of the methodology used to derive the 

model facility site-specific components of the capital and O&M compliance costs is also 

provided in Chapter 8 of the Technical Development Document (TDD). EPA used a model 

facility approach to develop the final rule compliance technology cost estimates. The technology 

modules used to model costs for the impingement mortality reduction technologies are based 

upon technology modules originally developed for the Phase II Rule which were then modified 

for the existing facility rule proposal. Since proposal of this rule, EPA adjusted all of the Phase II 

module costs for inflation and modified some modules in response to public comments received 

as described below. This, for the most part, has resulted in an increase in the total cost estimate 

for some model facilities and the industry as a whole compared to the estimates at proposal. 

For the cost of closed-cycle cooling technology in the final rule, EPA did not use the Phase II 

module costs but rather used a closed-cycle cost module presented at proposal that was based 

upon a cost estimation model provided by the Electric Power Research Institute (EPRI). EPA 

adopted this model because the costs are based on numerous facility-specific cost estimates to 

retrofit an existing facility with once-through cooling to closed-cycle cooling. Prior to proposal, 

EPA reviewed the underlying data and development of the estimation model and concluded that 

this model provides a good estimate of the compliance costs of an option based on closed-cycle 

cooling; see DCN 12-6656 and Chapter 8 of the TDD. EPA largely adopted the EPRI model for 

estimating compliance costs in the final rule. 

In response to public comments, EPA re-evaluated the engineering methodology for determining 

model facility site-specific costs subsequently used in the economic analysis, and used new 

information to revise these capital and O&M compliance cost estimates (including the 

methodology used for assigning technology compliance modules to model facilities in the 

costing analysis) for the final rule. 

Summary of Changes to Cost Estimation Methodology

In response to the public comments and new information, EPA has revised the proposal 

compliance cost estimation methodology in the following ways for the final rule: 

	 Capital costs for modified traveling screens with a fish return have been increased by 20 

percent, reflecting additional cost data from facilities and vendors. 

	 The capital cost for the fish handling and return component of the modified traveling 

screens has been increased by a factor of 2, reflecting additional cost data from facilities 

and vendors. 

	 For intakes where fish handling and return systems may be difficult or costly to install, 

the capital costs of the fish handling and return component of the modified traveling 

screens has been increased by a factor of 4. 

Essay 21 231 
	 The design through-screen velocity applied in estimating the costs to install a new larger 

intake module in the costing analysis has been decreased from 1.0 fps to 0.5 fps, which 

effectively increases the capital and O&M costs by a factor of 2. As a result, this cost 

reflects a technology compliant with the IM compliance alternative based on low 

velocity. Since a facility meeting that compliance alternative would not have to meet 

additional IM technology requirements, the costs associated with installing and 

improving the fish handling and return, which were applied in costing this module at 

proposal, are not necessary and therefore are not included. 

	 Technology assignment was changed such that modified traveling screens were assigned 

only to intakes with existing traveling screens because the modified traveling screen 

technology module only included costs for replacement of existing traveling screens and 

did not include costs for modifications to civil structures that may be needed if no 

existing traveling screens are present. 

	 Velocity caps alone (i.e., with no specification for an offshore intake location) were not 

considered as an IM compliance technology. Therefore facilities with this technology 

were assigned additional compliance costs. Existing velocity caps meeting EPA’s 

definition (including the requisite minimum distance offshore) are assumed to meet the 

IM standard, and incurred no further technology costs. 

	 A capital and O&M compliance module was developed for variable speed pumps 

(Module 15) in order to provide another method of compliance for facilities whose actual 

intake velocity is near (but still above) 0.5 feet per second. 

	 Costs are adjusted for inflation based on economic model timeframe 

Each of these changes is explained further in TDD Chapter 8. 

All other impingement mortality assumptions and methodologies remain unchanged from 

proposal. EPA notes that while a small number of facilities may be able to comply with the IM 

standard through the de minimis or low capacity utilization provisions, it did not assume any 

facilities would comply in either manner. To the extent that facilities may be able to comply with 

these provisions, EPA has overestimated costs for such facilities. 

The cost estimation methodology for closed-cycle cooling systems and other technology 

modules remain unchanged from proposal. 

IM Technology Cost Development

Baseline Compliance

Several commenters made general arguments that EPA had, for the proposal, overestimated the 

number of facilities considered already in compliance with the impingement mortality BTA 

standard. EPA disagrees. First, EPA based the determinations for the model facilities on survey 

data from actual facilities. This data was collected in the year 2000 and does not include more 

recent improvements made at facilities in anticipation of more stringent standards. In that 

respect, EPA may have underestimated the number of compliant facilities since EPA’s estimates 

do not include recent technology upgrades that have been made at a facility or required by 

Essay 21 232 
                                                            

permitting authorities. Second, in evaluating existing technologies for compliance for the final 

rule, EPA was careful only to designate specific technologies as IM compliant such as existing 

wedgewire screens (since most have design velocity of 0.5 fps), intakes with a design throughscreen velocity ≤0.5 fps, existing velocity caps if they were far offshore, and closed-cycle 

cooling (if all units served by the intake were closed-cycle). Modified traveling screens (as 

defined in the final regulation) were also assumed to have no additional technology capital costs; 

EPA used a relatively conservative approach and only considered those employing the key 

elements of a modified traveling screen reported in the 2000 survey, including a low pressure 

spray, fish buckets and a separate fish return as meeting the definition of modified traveling 

screens for purposes of costing.36 

The third reason EPA disagrees that it overestimated baseline compliance is that, for the final 

rule, EPA has included a greater degree of flexibility in the IM compliance standards allowing 

facilities, even individual intakes, to comply via a number of different alternatives, including one 

that allows for consideration of the combined impact of multiple technologies and operational 

measures (see preamble Section IV). EPA lacks the complete site-specific data to consider 

compliance based on combined systems of technologies. For example, the survey data shows that 

7 percent of facilities employ behavioral deterrence or fish avoidance systems. EPA does not 

have adequate performance data for each of these systems, nor does EPA have the site-specific 

biological data on which to determine whether the facility’s existing technologies meet the IM 

standard. EPA also expects some facilities will be able to take credit for their intake location 

(e.g., offshore submerged), flow reductions (e.g., seasonal operations or variable speed drives), 

new technologies (e.g., WIP screens, rotary screens), or credits for reused or recycled process 

water used as cooling water. Thus, while facilities with these control technologies may already 

meet the IM standard, EPA has assumed for costing purposes that none of these technologies 

contribute to compliance with the final IM standard. Further, in the costing EPA did not assume 

any facilities would have zero compliance technology costs as a result of a site-specific “de 

minimis” or low capacity utilization determination. 

In particular, some commenters cited concern that EPA assumed facilities that reported a design 

through-screen velocity ≤0.5 fps may not be able to meet the low velocity compliance alternative 

at minimum water depth and that facilities simply reporting traveling screens with a fish return 

may not in fact have the full array of features required by the proposed rule to meet the IM 

requirement. For the final rule analyses, EPA disagrees that the number of facilities considered 

as already compliant via the low velocity compliance alternative are overestimated. In response 

to comments concerning existing intake compliance with the low velocity compliance 

alternative, EPA examined the methodology used and design through-screen velocity and water 

depth data reported (see DCN 12-6602). EPA found that it assigned a total of only 11 percent of 

model facilities compliant with the IM standard via the low velocity compliance alternative. This 

11 percent breaks down as follows: 2 percent are estimated to have the reported the velocity 

based on critical low flow and should therefore be equivalent to the maximum velocity possible; 

5 percent reported a velocity enough below 0.5 fps that even if the mean water depth were 

36 In the final rule, modified traveling screens are not deemed IM compliant but are included here because the 

technologies listed are those that were assigned no compliance costs for technology upgrades. While no capital costs 

were assigned, these model facility intakes were assigned costs for the optimization study as were those facilities 

with intakes assigned traveling screens upgrade costs. 

Essay 21 233 
reduced by 30 percent, the velocity would still be compliant; and 1 percent used submerged 

wedgewire screens where water depth is irrelevant. EPA concluded that many of the remaining 3 

percent could meet the IM standard by measuring their actual intake velocity (40 CFR 

125.94(c)(3)) in lieu of the design velocity compliance alternative (40 CFR 125.94(c)(2)). EPA 

agrees that some of these facilities may not be able to achieve an intake velocity of 0.5 fps 

without additional costs, and has included the cost of variable speed pump retrofits for these 

facilities. EPA concludes this is reasonable because these facilities have actual intake velocities 

that are close to 0.5 fps, and therefore installing variable speed pumps will allow these facilities 

to ensure the actual velocity stays below 0.5 fps during periods of low flow. EPA notes that 39 

percent of facilities did not report velocity data; therefore EPA conservatively assumed all of 

them were greater than 0.5 fps. Thus, while there may be some instances where model facilities 

deemed IM compliant by EPA may actually require some compliance upgrades, there are also 

many other instances where EPA’s conservative approach results in costs for technology 

upgrades that may not be necessary. Further, there are likely instances where facilities that did 

not report velocity data can in fact comply with one of the intake velocity compliance 

alternatives with no additional costs (40 CFR 125.94(c)(3) or 40 CFR 125.94(c)(2)). 

Regarding the concern that facilities with fish returns may not have the full array of modified 

traveling screen features, see the baseline compliance section below. 

In the case of velocity caps, one commenter noted that EPA appears to assume that velocity caps 

will comply because they met the low velocity compliance alternative but that many do not and 

may incur costs associated with entrapment. There are three scenarios where velocity caps are 

addressed by the final rule. In the first scenario, the design or actual intake velocity is below 0.5 

fps, and the facility can choose one of the two intake velocity alternatives discussed above. In the 

second scenario, where the velocity cap is far offshore as defined in the regulation as 800 ft or 

more, EPA’s data shows that the combination of an offshore location and the behavioral 

deterrent effect of the velocity cap design result in performance equal or greater than IM BTA. 

See preamble Section VI for further discussion. EPA has revised the final rule to provide that 

offshore existing velocity caps (meeting the final rule’s definition) will comply based on intake 

location and intake structure design (but NOT velocity as indicated by commenters). EPA’s 

assumptions about existing velocity caps as meeting the IM requirements for costing purposes 

are consistent with the rule’s definitions. Only those existing velocity caps that meet the 

definition of offshore included as pre-approved in the final rule are assumed to be compliant. 

Further, EPA has removed specific entrapment requirements for reasons stated in the final rule 

preamble Section VI. In the third scenario, EPA allows the possibility that a velocity cap is built 

after issuance of the final rule. A facility could choose to demonstrate that the velocity cap meets 

the IM standard via the compliance alternatives 40 CFR 125.94(c)(6) or 40 CFR 125.94(c)(7). 

EPA did not assume any facilities will choose to do this, and has not costed any facilities to 

install a new velocity cap. Upon review of all three scenarios, EPA is confident that its costing 

methodology for existing offshore velocity caps is consistent with and reflects the final rule. 

Costing Technology Selection

Commenters expressed concern that EPA estimated costs only for a relatively small range of 

selected technologies and that upgraded modified traveling screens may not be able to meet the 

standards. EPA recognizes that it has relied on a simplified approach to model the costs to 

Essay 21 234 
                                                            

 

 

comply with the IM standard and that to develop costs that accurately represent the compliance 

approach for some facilities would have required a more detailed site-specific analysis. Reliance 

on the simplified model was, in part, due to the lack of the necessary detailed site-specific 

information. Lacking this information, EPA could not tailor the technology selection for its 

costing analysis to meet site-specific conditions to ensure compliance. Rather, EPA selected 

from a suite of technologies that are anticipated to be compliant in many circumstances and 

would apply in a variety of situations. These technologies are representative of a wide range of 

costs. EPA estimated costs for modified traveling screens with fish returns where this technology 

was clearly available (i.e., intakes with existing traveling screens that did not have very high 

through-screen velocities37). Where modified traveling screens were not the most cost-effective 

compliance path or where such screens may not be the selected alternative, costs are estimated 

for technologies that could easily meet the velocity compliance alternatives such as wedgewire 

screens and new larger intakes because they have relatively high compliance costs and could 

serve as conservative surrogates for the possible range of technologies that ultimately may be 

employed. EPA applied these technologies, particularly wedgewire screens, based on certain 

site-specific conditions such as waterbody type, design intake flow, and water depth.38 EPA 

recognizes that, in many cases where these technology modules are assigned, a lower cost 

technology or mix of technologies may be a more cost effective approach for facilities to meet 

the IM standards. EPA has included a high degree of flexibility in meeting the IM standard by 

providing multiple pathways for compliance including one that gives credit for combinations of 

technologies and operational measures (see Section IV of the preamble). EPA fully expects 

facilities will evaluate each IM compliance alternative and select the most cost-effective 

approach to compliance. Using information in the record, EPA was able to determine a 

technology that was likely feasible for a model facility, but EPA recognizes that a facility could 

select another compliance approach because it is less costly. Therefore, while facilities may not 

elect to comply using wedgewire screens or larger intakes, if the facilities can bear the costs of 

these expensive technologies, then EPA reasonably concludes the facilities can afford less 

expensive technologies. 

One commenter stated that EPA overestimated the number of facilities that could comply via 

modified traveling screens because they would have difficulty meeting the 12 percent proposed 

annual impingement standard. As a result, commenters assert EPA underestimated the number of 

facilities that would need to comply via the more costly low velocity compliance alternative. 

37 EPA was concerned that some intakes with traveling screens may include design parameters that are outside the 

range typically employed. For example, intakes in high sediment load waters may use unusually high intake 

velocities to avoid sediment drop out in front of the intake. Performance data from facilities with traveling screens 

and high sediment waters do not show that the high velocity, in most cases, results in any diminished performance. 

However, in response to comments, EPA has not been able to rule out the possibility. Accordingly, the final rule at 

40 CFR 125.94(c)(5) provides that the Director will review the impingement technology performance optimization 

study at 40 CFR 122.21(r)(6)(i), and then the Director will determine whether the modified traveling screens is the 

best technology available for impingement reduction at the site. For purposes of costing this provision, EPA 

conservatively assumed that having a through-screen velocity of greater than 3.0 fps provides a criterion for 

identifying intakes with traveling screens where an alternative technology may be necessary. As indicated above, 

such traveling screens (when upgraded) likely would meet the BTA requirements, but EPA has included this higher 

cost option for a select subset of model facilities to account for instances where other more costly technologies may 

be more required.

38 Wedgewire screens were only assigned to those intakes where design considerations such as screen size, water 

depth, and waterbody type indicated sweeping velocities are compatible with basic technology limitations. 

Essay 21 235 
                                                            

EPA disagrees that it has underestimated costs in this way for the final rule. First, EPA notes the 

numeric IM performance standard has been revised; there is no longer a monthly standard, and 

the numeric IM performance standard has been revised to represent a 12-month level of 

performance. See Section VI and Essay 16A for more information. Second, in the final rule EPA 

has established seven alternative impingement standard compliance pathways and only one of 

these alternatives relies upon monitoring to meet the numeric impingement mortality 

performance standard. Compliance alternative 40 CFR 125.94(c)(5) specifically addresses 

modified traveling screens. As discussed in Section VIII of the preamble, EPA estimates that a 

very small portion of facilities will select monthly biological monitoring to demonstrate 

compliance with the numeric IM performance standard. EPA has provided the IM performance 

standard as a performance benchmark for all BTA technologies, including new and innovative 

technologies yet to be demonstrated. As a result, facilities have much more flexibility in 

achieving compliance, eliminating the concerns raised by the commenter related to the limited 

choices available for compliance. See Section VI of the preamble for more information. 

In the proposed rule, EPA required performance equivalent to barrier nets as a technology to 

minimize the impingement of shellfish at estuarine and marine intakes. Several commenters 

noted that at proposal, barrier net costs were not included for certain facilities on tidal rivers and 

others stated that the requirement is not necessary. At proposal, due to the limitations of the 

survey data, EPA used additional data to distinguish intakes on brackish tidal rivers from those 

on freshwater rivers or streams and assigned waterbody type and technologies accordingly. Some 

waterbody type designations may vary from those of the commenters. In the final rule, EPA is no 

longer including a separate requirement to reduce IM of shellfish at estuarine and marine intakes 

because the revised average percent survival performance standard accounts for shellfish as it 

includes data on shellfish survival. See Essay 18 and Section VI of the preamble for more 

information. Accordingly, in the final rule compliance cost analysis, EPA included barrier net 

costs for intakes in marine environments.39 EPA notes that the final rule allows the Director to 

establish additional requirements, such as barrier nets, for protection of shellfish at 40 CFR 

125.94(c)(8). The Director may also establish additional measures for other species at 40 CFR 

125.94(c)(9). EPA’s cost estimates appropriately do not include costs that may result from these 

additional site-specific determinations because EPA cannot predetermine the outcome of such 

determinations and the final rule does not prescribe a particular requirement. See TDD Chapter 8 

for more details on EPA’s costing approach specific to marine environments. 

Many commenters stated that the low velocity compliance alternative is inflexible and cannot be 

met without high costs, or perhaps not at all. EPA agrees that at certain facilities, compliance via 

the low velocity compliance alternative may not be feasible or the most cost-effective way to 

meet the IM standard. The final rule does not require facilities to meet a low velocity 

requirement. Rather, low velocity alternatives (on a DIF or AIF basis) are two out of seven 

compliance alternatives for the IM standard. Further, the low velocity compliance alternative 

itself is flexible in that it allows for either compliance via the design intake flow (thus indicating 

the maximum intake velocity based on the intake design) in which case no further monitoring is 

required; or via the actual intake flow where facilities that consistently operate below the design 

intake flow volume may demonstrate via monitoring the facility’s actual intake flow. As 

39 EPA did not include costs for barrier nets for intakes in freshwater streams because data indicate shellfish are not 

present in these waters. 

Essay 21 236 
                                                            

 

discussed above, in the compliance cost analysis, for many of the intakes that did not employ 

existing traveling screens and where the low velocity alternative could not be met without 

modifying the intake, EPA assigned costs for a new larger intake or submerged wedgewire 

screens with a design through-screen velocity of 0.5 fps. EPA agrees that for intakes where the 

existing screen area is too small to comply with the low velocity alternative that construction of a 

larger or submerged intake represent a fairly high cost option compared to upgraded traveling 

screens. In this regard, EPA views the cost analysis as conservative, as discussed above. 

Technology Costs – Overarching Comments

Some commenters argued that EPA’s cost estimates for IM and EM technologies are flawed 

because they are based on large facilities and then scaled down for smaller facilities such as 

manufacturers that use as little as 2 mgd. EPA disagrees. In theory, extrapolating a cost curve 

towards zero or infinity results in unreasonable results. However, EPA’s cost models have two 

boundaries to avoid such conditions. First, the cost curves are not applied to intake flows below 2 

mgd. Second, for several technologies, the cost tool imposes a minimum cost below a specified 

point (or in this case, below a certain threshold).40 If EPA does not have costing data for a 

specific technology below a certain intake flow, it used the costing data for the lowest flow 

available. For example, for variable speed pumps, all intakes less than 10,000 gpm received the 

same cost as that was the lowest intake volume for which EPA had costing data. This likely 

overstates costs for lower flow facilities, but EPA does not have the data to refine this cost 

assumption any further. See TDD Chapter 8 for information on thresholds for various 

technologies. Furthermore, EPA’s technology module cost estimates generally use equations 

based on costs curves that were derived using technology scenarios of varying sizes; as a result, 

EPA is already considering the possibility of higher unit costs at lower flows. The exceptions are 

those cost modules that used linear equations (closed-cycle and variable speed pumps), which 

were derived for larger systems and would have underestimated technology costs for low flow 

intakes if EPA had not established minimum costs below certain intake volumes as described 

above. More specifically, to account for the possible underestimation of variable speed pump 

costs, a minimum capital cost was established such that the lowest flow facility costs would not 

be understated. For module 15, for design flows below 10,000 gpm (or about 14 mgd), the 

minimum costs are set equal to the capital cost value for a 10,000 gpm system (rather than using 

the equation). 

Commenters on the proposal noted that EPA had assumed no incremental costs to meet the “no 

entrapment” requirement. This is appropriate for the final rule because the final rule did not 

establish any additional requirements for entrapment. See Essay 18 for more discussion 

regarding entrapment. 

Some commenters on the proposal stated that for its earlier analysis, EPA has underestimated the 

costs of traveling screens. Several compared the costs derived using the EPA cost tool to vendorquoted costs and noted that for their intakes, their estimated capital costs ranged from about 44 

percent to several times greater than EPAs model costs. Some of these are discussed in greater 

detail below. EPA considered these comments, as well as new information including a review of 

40 For traveling screens a minimum screen width was imposed and for variable speed pumps a minimum cost was 

imposed for intakes less than 10,000 gpm. See TDD Chapter 8. 

Essay 21 237 
actual traveling screen replacement costs obtained during site visits (see DCN 12-6654) and 

agrees with commenters that some cost adjustments are warranted. As a result of the revised cost 

data, for the final rule, the capital cost of traveling screens has increased by a factor of 20 

percent. See preamble Section V for further discussion of changes in costs since proposal. EPA 

also re-evaluated the costs of the fish handling and return component in light of public comments 

arguing that some facilities may encounter site-specific difficulties in the design of a fish return. 

Upon review of the newly provided facility and vendor data, EPA concluded that the proposal 

cost estimates represented an “easy” retrofit situation. However, EPA has little data that singles 

out the capital and installation cost of just the fish return. One cost set indicative of a “somewhat 

difficult” level installation for a fish return was about 3 times EPA’s cost, whereas another data 

set for a “low difficulty” level installation was found to be similar to EPA’s cost. To account for 

a small subset of more difficult situations, EPA increased the fish return and spraywater pumps 

capital cost resulting in a total final capital cost that is four times the costs at proposal for these 

components (i.e., fish return and spraywater pumps). This allows for “difficult” level installation 

costs consistent with the new data, and results in a cost for the “non-difficult” fish return and 

spraywater pump that is twice that of proposal. For details, see TDD Chapter 8. In order to 

confirm the validity of the revised traveling screen cost estimates, EPA compared actual costs for 

traveling screen replacement obtained during site visits with the revised cost model results and 

concluded that the EPA costs are comparable (see DCN 12-6654). 

One commenter (UWAG comment 2210, which represents the power industry) argued that EPA 

underestimated the O&M costs for traveling screens. They note that the costs should include: 

labor hours needed to maintain the fish collection and return systems; installation costs including 

(for example) crane costs associated with screen removal or intake bay dewatering during major 

overhauls; spray water system replacement and overhaul; and fish return system replacement due 

to cracking and erosion. EPA disagrees that it has underestimated O&M costs for traveling 

screens and concluded that the traveling screen O&M cost modules represent a reasonable 

estimate of average O&M costs. The O&M costs are based on labor hours cited by a vendor 

which includes system overhauls of the traveling screens and the spray systems, both of which 

are integral components of the system. The O&M costs also include material costs for equipment 

replacement components that are based on a percentage of equipment costs. This percentage is 

also based on a vendor recommendation. EPA however, did not include costs of dewatering since 

facilities with most intakes are already equipped with stop logs or gates that facilitate 

dewatering, and EPA found in site visits that most facilities have the ability to continue facility 

operations while a specific forebay is removed from service. EPA also notes that this technology 

cost was only assigned to intakes with existing traveling screens and that the O&M costs are 

incremental costs. Some of the components cited such as screen overhaul and installation, 

dewatering, and spray system (high pressure) were already being performed prior to the upgrade 

and thus should not be included in the cost estimate. While the existing screens may not be 

designed for continuous operation and would require more frequent overhaul if operated 

continuously, EPA included costs for complete replacement using screens with a more robust 

design that minimizes maintenance due to wear. Other costs associated with new components are 

included in the vendor estimates which were described as the net increase over current 

conditions. Therefore, EPA has concluded any incremental costs were included in the O&M 

estimates. EPA notes the commenter did not provide any specific data on this issue. EPA also did 

not include costs of a crane since the actual need for a crane and the frequency of use can be 

highly variable. Further, EPA expects such construction work would be done during outage 

Essay 21 238 
periods, during other construction activities, and on a schedule determined by the Director that 

would reflect any additional controls for entrainment (see preamble Section IX for more 

discussion on compliance schedules). In most cases, any work is expected to occur when heavy 

equipment is already available. Therefore, mobilization and transportation costs for heavy 

equipment would not be an incremental cost resulting from the requirements of this final rule. 

Further, EPA has included a contingency factor in the cost analysis to reflect those site-specific 

instances where costs may be inadvertently understated; see TDD Chapter 8. 

Another commenter on the proposal (commenter 2171) stated that O&M costs assumed by the 

EPA for modified traveling water screens were underestimated, and EPA did not include cost 

and maintenance of replacement fixed screens when screens are sent offsite for overhaul and 

replacement. As discussed above, maintenance overhaul of traveling screens is an activity that is 

already performed for the existing screens and thus should not be included, regardless of 

methodology employed. EPA based screen replacement costs on vendor quotes for a typical 

replacement, which should not require an extended period of fixed screen use under normal 

circumstances. EPA notes the commenters provided no supporting data for their assertions. 

Based on further review, EPA has concluded that the O&M costs estimates it used for the final 

rule are reasonable estimates because they are based on vendor quotes and available data rather 

than unsupported assertions. Since no detailed information or cost data has been received by 

EPA to suggest that traveling screen O&M costs are underestimated, EPA disagrees with these 

comments. 

UWAG stated that EPA’s barrier net costs are low, arguing that costs for components such as 

pilings and O&M cost are underestimated. They note that in TDD Chapter 12-2, EPA claims that 

if all 139 tidal facilities installed barrier nets the costs would be only $4,010,000 ($28,849 per 

facility) and UWAG stated that it was unclear whether the cost basis was total or annualized and 

whether it included O&M costs. A Southern Company (comment 2190) estimate suggested that 

the capital costs for barrier nets on oceans and tidal waters to minimize impingement of shellfish 

from existing water flow would be $4,000 per cfs (equal to approximately $9 per gpm). Based on 

the discussion below, EPA disagrees that the cost estimates for barrier nets are underestimated. 

EPA notes that the barrier net costs shown in TDD Chapter 12-2 for the final rule are annualized 

costs, which include (and are largely driven by) O&M. The O&M is primarily associated with 

removal/deployment, repair, and replacement of the barrier nets. EPA based the cost estimates 

for barrier nets in estuarine environments on cost information provided by Chalk Point that 

reflect the actual design and operation at their facility. EPA concluded that the barrier nets at 

Chalk Point (which includes a robust design with two concentric nets and fixed pilings) that have 

demonstrated an 80 percent reduction in IM are well-suited for use as an example of a wellfunctioning barrier net in an estuarine environment. Chalk Point did not provide information on 

installation costs for the pilings. Instead, EPA based its estimate for initial barrier net installation 

on more general unit cost data for marine pilings installation. The final rule barrier net costs were 

adapted from the Phase II cost module and a description of the derivation of costs can found in 

Chapter 4.1 of Phase II TDD. The design flow for the Chalk Point Plant was greater than 

800,000 gpm and the Phase II TDD Table 4-7 shows that for a 20 ft deep net, an intake with a 

design flow of 807,840 gpm would need 152 pilings at a cost of $162,792 plus 20 percent 

($32,558) or $195,350 in 2002 dollars. A comparable cost estimate for Chalk Point derived using 

the EPA final rule cost tool results in a total capital cost of approximately $220,000 and an 

annual O&M of approximately $92,000 in 2009 dollars. UWAG cited a cost of $200,000 (2006 

Essay 21 239 
dollars) for the actual piling design at Chalk Point which demonstrates that EPA’s estimate for 

barrier net support structure installation tends to conform with the commenter’s estimate. EPA’s 

final estimated costs for barrier nets include a substantial component for O&M that includes 

labor costs for routine maintenance, seasonal deployment, and annual replacement of 1/3 of the 

net each year (see Chapter 4.2 of the Phase II TDD). These costs are based on costs cited by 

Chalk Point for use of a contractor to periodically remove and replace the nets with clean nets, 

plus replacement costs for damaged nets and therefore EPA’s barrier net costs include O&M 

costs that are reflective of actual cost of a well-functioning barrier net. The O&M costs of 

$75,000 to $88,000 (2006 dollars) per year to control biofouling at Chalk Point cited by UWAG 

is very similar to the comparable EPA O&M cost of $83,250 (2002 dollars). The 20 ft depth 

scenario was used as a default costing assumption for all ocean and estuarine intakes. Southern 

Company cited capital cost rate is nearly an order of magnitude higher than comparable EPA 

cost estimates. They provide no description of the basis for their cost estimate and therefore 

cannot be directly compared. As described above, the EPA cost estimates are based on a detailed 

breakdown of cost components, a portion of which is confirmed by cost data cited by UWAG. 

Comments Concerning Capital Costs for Specific Facilities

EPA recognizes that for individual facilities, actual costs may be higher or lower than the 

average based on site-specific conditions. However, for purposes of national rule cost estimates, 

the cost model based on average costs provides a reasonable approach since these differences 

will tend to balance out. The final rule includes many compliance alternatives in addition to 

those included in the proposal and that these alternatives may provide less costly approaches to 

meeting the IM standard than anticipated at proposal. Recognizing that each of these companies 

may reconsider their compliance approach in light of the additional compliance alternatives, 

EPA is responding to the specific comments. 

Many commenters provided total compliance cost estimates for one or more facilities in support 

of their argument that EPA underestimated the costs. In many cases, EPA is unable to directly 

respond to these comments since the commenters provided only total costs and did not include 

any supporting data or detailed information describing system design or how the cost estimates 

were developed. In other cases, facilities included total costs that also included costs to comply 

with other rules (such as the Utility Air Toxics rule) and EPA was unable to determine whether 

the costs were related to complying with today’s rule or the other rule. It is not appropriate to 

include compliance costs for other rules in developing the incremental compliance costs for 

today’s rule. Such costs were already considered in EPA’s compliance cost estimates for those 

final rules. 

The Wisconsin Public Service Corporation provided estimated aggregate O&M cost for 

continuously operated traveling screens at their Pulliam Plant of $240,000 and $330,000 at their 

Weston Plant. They compare these costs to “agency’s site specific estimated O&M costs for the 

J.P. Pulliam and Weston Generating facilities are $271,000 and $88,000, respectively.” EPA is 

unable to respond to these estimates in a detailed manner since the commenter provides no 

details regarding the source of the EPA estimates they cited and/or how they were derived. 

Further, no details regarding the derivation of their own estimates were provided except that they 

include costs for increased power and maintenance/repairs assuming the traveling screens 

operate continuously when pumps are in service. EPA notes that these two facilities completed 

Essay 21 240 
short technical surveys only and are therefore not included in the model facility estimates for the 

final rule. However, the commenters O&M estimate for the Pulliam appear to be in agreement 

with the EPA estimate they cited. EPA notes that flow is a major input value driving costs and 

based on technical survey data, the design intake and average intake flow for the Weston is about 

3 times that for the Pulliam. The commenter failed to provide information (nor does EPA have 

any other site-specific information) that would explain why their own O&M estimate for a 

facility with 1/3 the flow volume would have O&M cost that is only decreased by 38 percent 

from that of the larger facility. As a result, EPA disagrees with the comment and did not make 

changes to its cost methodology or to any facility-specific costs. 

A comment from ConocoPhillips Company, Bayway Refinery stated that total replacement of 

traveling screens at Bayway refinery would cost $5-10 million (including screen replacement, 

engineering reviews, and configuration of a fish return but not including screens for the reservoir 

intake or barrier nets). The commenter provided an overall estimate but did not similarly provide 

estimates of the individual components included in that total. For the final rule, EPA estimates 

that the capital cost to comply with the IM standard via replacement of existing traveling screens 

with modified traveling screens including the addition of a fish return would be $3.6 million. 

EPA acknowledges the difference in the two capital cost estimates. However, EPA is unable to 

determine why the EPA and Conoco cost estimates differ because the commenter did not provide 

any supporting data or detailed information describing system design or how the cost estimates 

were developed. It is also unclear whether the commenter’s data reflects incremental costs or a 

full replacement of the entire intake structure. In absence of more specific information (which 

the facility did not provide), EPA concludes its cost estimate is a reasonable reflection of 

probable costs for the facility. 

A comment from the Astoria Generating Company (comment 2193) stated that the projected 

capital cost for retrofit of the screens for Units 30, 40, and 50 at Astoria Generating Station for 

the facility is $9.75 million. The facility did not provide any detailed information on the 

components included in that cost or information on how it developed its costs and EPA does not 

have specific data concerning the size and number of screens employed. EPA notes that if units 

30, 40, and 50 each utilize two 10-ft wide screens (which is a typical configuration for facilities 

this size), the corresponding EPA projected capital costs for modified screens with fish returns 

would be approximately $5.7 million for 50-ft tall screens in 2009 dollars. EPA acknowledges 

the difference in the two capital cost estimates. However, EPA is unable to determine why the 

EPA and Astoria cost estimates differ because the commenter did not provide any supporting 

data or detailed information describing system design or how its cost estimates were developed. 

In absence of more specific information which the facility did not provide, EPA concludes its 

cost estimate is a reasonable reflection of probable costs for the facility. 

The Astoria Generating Station has estimated that an additional 4 bays of similar configuration to 

the existing bays would be required at AGS if they were required to attain a through-screen 

velocity of less than 0.5 fps. They estimated the costs would be $32.9 million based on a 

complete reconstruction of the intake structure and inclusion of modified traveling screens and a 

fish return. EPA notes that the compliance technology design proposed by Astoria in this 

instance consist of modified traveling screens, a fish return, and a reconfiguration to 0.5 fps. This 

facility would likely install modified traveling screens or reconfigure its system to comply via 

the low velocity compliance alternative, but not both. This compliance response goes beyond the 

Essay 21 241 
                                                            

 

final rule IM requirements. As such, the cost estimate provided by this facility is, by its very 

nature, higher than EPA’s estimate. Having said that, EPA applied its costing modules to the 

scenario described by the commenter. Based on the available design through-screen velocity of 

1.0 to 1.1 fps reported for the intakes at this facility, EPA estimates that a total screen width of 

around 100 ft or more would be needed to meet the 0.5 fps compliance alternative. Assuming a 

total screen width of 100 ft, EPA has calculated capital costs for a larger intake with traveling 

screens (Module 10.2) would be approximately $22 million. These costs do not include modified 

traveling screens or fish returns because the larger intake is built to meet the 0.5 fps velocity 

compliance alternative. Consequently, the corresponding cost to meet only the low velocity 

alternative for the Astoria Generating Station should be significantly less than the $32.9 million 

cited. 

A comment for Cook Nuclear Plant provided a capital cost estimate for a fish return and 

handling system of over $3 million dollars. Further, the comment urges EPA to acknowledge that 

fish collection and return systems are not easy, potentially not feasible, and inexpensive to 

retrofit at some facilities. They explain that the Cook Nuclear Plant operates seasonally a fish 

deterrent system that uses high frequency sound to repel fish, particularly species of the 

Clupeidae family. They state that the combination of its velocity cap, its offshore intake location, 

and its fish deterrent system would likely eliminate the need for a fish collection and return 

system, and the Cook Nuclear Plant expects that it could demonstrate an equivalent level of 

mortality reduction, consistent with EPA’s goals for the 316(b) rule. EPA agrees that fish returns 

may be more challenging to install at some sites, but maintains that the technology is available 

and demonstrated. Further, EPA has adjusted the cost of fish returns as described above to reflect 

more difficult installations. However, EPA agrees with the commenter that they may not need to 

install a fish return and handling system. As explained in the preamble, the final rule provides 

seven compliance alternatives for demonstrating compliance with the IM standard, several of 

which are potentially relevant at the example facility described in the comments: existing 

velocity cap, intake velocity, and the “system of technologies.” See the preamble for further 

discussion of the alternatives. Because, similar to the facility, EPA expects the facility would not 

need to install a fish return and handling system and would not incur such costs, EPA 

appropriately did not estimate costs for this facility to add a fish return or handling system and 

the facility’s estimate is not relevant. 

The Eastman Company presented a $20 million cost estimate for traveling screens for their 

Tennessee facility and argues that these costs are much higher than costs derived by EPA. They 

perform comparisons to two different EPA cost estimates. The first EPA estimate used for 

comparison to their $20 million estimate was derived using the impingement compliance 

technology cost factors in Exhibits 8-19 of the proposal TDD that EPA used in the IPM model 

analysis which derives costs by multiplying design flow (in gpm) by a factor.41 This cost factor is 

based on total costs and total design flow and represents an average for all facilities on a national 

basis. While EPA did revise the corresponding impingement technology costs for traveling 

screens in response to comments in the final rule such that the IPM capital cost factor 

representing the average technology costs increased from $13.1/gpm to $20/gpm, the equivalent 

41 As part of the economic analysis, EPA used the Integrated Planning Model (IPM) to estimate economic impacts. 

To facilitate the modeling runs, EPA developed specific cost equations; see Chapter 8 of the TDD for more 

information. 

Essay 21 242 
                                                            

cost of roughly $10 million for the Eastman facility was still only about half the Eastman 

estimate. As the commenter is comparing a site-specific cost to one EPA developed to represent 

a national average, EPA would expect that some site-specific costs would be higher (and some 

would be lower) than those predicted by a national average. 

The second EPA estimate used for comparison by Eastman Company to their $20 million 

estimated capital costs for freshwater modified traveling screens was presented in Exhibit 3-27 

of the Phase III TDD. EPA agrees that the costs and methodology presented in Exhibit 3-27 were 

the basis for the cost equations used to develop costs estimates for the proposed and final 

existing facilities rule but notes that the costs in Exhibit 3-27 are in 2002 dollars and that, based 

on the ENR CCI, the costs should be increased using a corresponding inflation factor for 

adjusting 2002 to 2011 dollars of 1.4 (9070/6538) before the commenter can reasonably compare 

the costs. For the final rule EPA has adjusted the capital costs for traveling screens based on data 

such as vendor data and facility data such as that provided by the commenter. Eastman notes that 

they intend to use dual flow screens which, as described in the Phase II TDD, EPA had 

concluded would add an additional 20 percent to the capital costs but would result in lower 

facility operating and maintenance costs due to reduced debris carryover which would not be 

reflected in the traveling screen O&M costs. When these adjustments are incorporated, their 

original EPA estimate increase from $4.5 million to around $10 million. 

Insufficient data is available for EPA to verify the cost components including the screen costs 

cited in comments. However, one assumption that drives Eastman’s estimate up is their inclusion 

of a contingency factor of 30 percent. EPA disagrees with Eastman’s use of a contingency factor 

of 30 percent. Contingency factors are added to reflect unexpected costs that may occur. 

Typically, contingency factors reflect the complexity and the degree of uncertainty regarding the 

scope of the work being performed. That is, a more complex application and especially one 

where the scope of various components and tasks have a high degree of uncertainty would 

include higher contingency factors that less complex and uncertain applications.42 In the 

modified traveling screen cost module, EPA used a contingency factor of 10 percent reflecting a 

more reasonable contingency rate for an average facility because traveling screen upgrades 

involve replacement of existing technology with no major modification of existing civil 

structures. The technology is well-demonstrated, well-understood, retrofit of such technology is 

already done by the industry, and therefore the uncertainty of costs is relatively low. A higher 

contingency factor such as that described by the commenter would be appropriate where the 

technology is poorly understood, undemonstrated, or uncertainty about the retrofit process was 

extremely high. The commenter goes on to point out that the overall EPA methodology may be 

accurate for some average facilities, and EPA agrees with the comment. The commenter goes on 

to assert that the cost to retrofit large pieces of new equipment into very old buildings will often 

far exceed the median estimated cost for an average facility. Eastman notes that many of their 

intakes were built in the 1920s, 1930s, and 1960s. EPA notes that the estimated costs of this rule 

are incremental costs, and are not intended to represent the costs of other upgrades a facility may 

need to undertake or, in the absence of any rule, choose to undertake. EPA notes that this may 

explain Eastman’s use of an additional 30 percent cost increase applied to equipment costs for 

42 For example, projects where civil structures must be modified or constructed and where strategies for dealing with 

interference with existing utilities and structures have not been fully developed will involve a higher degree of 

complexity and uncertainty. 

Essay 21 243 
“Civil / Structural, Concrete, Steel and Misc.” EPA considers this cost high as compared to the 

average facility which is the basis for EPA’s estimates. EPA also notes that Eastman included 2 

percent escalation factor over a seven year period (2011-2018) which increased costs by 14 

percent or another $2 million. Escalation is used to account for increases in the price of goods 

and services over time and typically is included to account for increases during the duration of 

the project. EPA does consider such costs in the economic analysis but not in the overnight cost 

estimates which were used for comparison here. EPA does not consider the inclusion of a 14 

percent escalation factor for a project that should have relatively short duration to be appropriate 

in this case. In any event, costs escalated to 2018 are not comparable to an EPA 2011 estimate. 

EPA concluded that the Eastman $20 million estimate includes a contingency cost that is inflated 

by $3 million (30 percent versus 10 percent), a “Civil / Structural, Concrete, Steel and Misc” cost 

component of $2.4 million that appears excessive, and an escalation cost of $2 million that is 

inappropriate for this comparison. When factored into this comparison, the difference of roughly 

$10 million (about 50 percent lower) between the revised EPA estimates and the Eastman 

becomes much smaller (equal to roughly 25 percent lower). Based on this discussion, EPA has 

concluded that the Eastman capital cost estimate does not conflict with the EPA estimates for 

modified traveling screens by a significant amount but rather the differences in total costs reflect 

Eastman’s use of certain cost components that EPA does not consider as appropriate in the 

application of this technology. Further, as explained previously, EPA’s model facility approach 

estimates costs on a national basis. As such, some facilities will experience cost above the 

national average and some will experience costs below the national average. 

Service Life

Several commenters argued that EPA has overestimated the service life of technologies. One 

commenter (UWAG) noted that EPA estimated the service life of traveling screens as 20 years 

but notes that they commonly are replaced or overhauled every three to five years due to 

continuous operation and extensive O&M requirements. As described below, based on 

information it its record, for most facilities, EPA concludes 20 years is a reasonable estimate of 

the service life of traveling screens. However, EPA agrees with the commenter that many screens 

will require ongoing maintenance, replacement, or overhaul during this time period and that, for 

some, the lifetime may not extend to 20 years. EPA’s costing approach reflects that and as such 

do not result in underestimates of cost. Observations from EPA’s site visits confirms that under 

certain circumstances, such as rivers with persistently levels of suspended silt and sand levels, 

traveling screens may require overhauls at higher frequencies but notes that this is only a small 

subset of intakes. These overhauls typically involve replacement of certain moving parts such as 

specific screen panels, the bay, motor, cover, and mounts. An overhaul does not entail 

replacement of the entire traveling screen. EPA notes that newer traveling screen units are 

designed with sturdy but lightweight composite materials, which greatly decrease wear and tear 

on moving parts and decreases operational costs. Under high sediment loads, EPA found that 

facilities replace chain and sprockets, and individual screen panels. This is consistent with EPA’s 

O&M costs based on vendor quotes of typical labor and equipment costs associated with ongoing 

maintenance including equipment overhauls. EPA has concluded that these costs are 

representative of full range of O&M costs associated with a service life of 20 years. 

The commenter also stated that EPA assumed a service life of 30 years for barrier nets but that 

many such nets are replaced more frequently (e.g., every 2-3 years). EPA notes the commenter 

Essay 21 244 
misunderstood the methodology. EPA agrees that many barrier nets may require frequent 

replacement. EPA’s technology costs for barrier nets include O&M costs for the replacement of 

one third of the nets each year. This is consistent with the commenters suggested frequency. The 

30 year service life assumed by EPA applies only to the more permanent components such as 

pilings and anchor points. Other commenters were less specific about their concern for EPA’s 

assumed length of service life for technologies and EPA is unable to respond to these comments 

since they are general in nature and no information is provided regarding specific technologies or 

service life duration. 

Entrainment Costs Development for Existing Units/Intakes

Industrial stakeholder commenters argued that the cost analysis fails to include any costs for 

entrainment requirements. The rule establishes a BTA standard for entrainment that requires the 

determination of required entrainment reduction measures in a structured site-specific permitting 

proceeding. The BTA standard for entrainment requires that certain prescribed factors must be 

considered in the decision and must reflect the maximum reduction in entrainment warranted 

after consideration of relevant factors. EPA’s cost estimates include the costs of studies and 

analyses that are required to be submitted to the Director for a site-specific determination of 

BTA for entrainment. However, EPA has not included compliance cost estimates for any 

entrainment reduction technologies because, under EPA’s selected option, compliance for 

entrainment reduction requirements is established on a site-specific basis. EPA cannot 

predetermine the outcome of such determinations and this final rule does not prescribe a 

particular requirement. EPA did, however, develop cost estimates for the cost of several 

compliance options at proposal that included entrainment compliance costs, including an 

assessment of the cost of an option that would have required flow reduction equivalent to that 

achieved by closed-cycle recirculating systems at all facilities with 125 mgd or greater (Proposal 

Option 2), which account for 90 percent of actual flows. Also see Essays 37 and 55 for additional 

discussion concerning entrainment cost and impact evaluation. 

Several commenters provided total facility technology costs for one or more facilities to comply 

with a closed-cycle cooling requirement. EPA is unable to evaluate these estimates since the 

commenters provided only total costs without a breakdown among component costs (e.g., O&M, 

capital), and did not include any supporting data or detailed information describing system 

design or how the cost estimates were developed. 

Regarding closed-cycle, low flow cooling systems are, in many cases, associated with 

manufacturing facilities and EPA’s approach was to account for higher compliance costs at 

manufacturing facilities reflecting more complex cooling systems by applying capital costs based 

on EPRI’s difficult retrofit cost category. Upon further analysis, EPA has confirmed the validity 

of the manufacturing facility costs as reasonable for medium and large systems, but 

acknowledges that the cost model may have underestimated closed-cycle retrofit costs for 

smaller manufacturing systems due to extrapolating the cost curve to small flows. This cost 

underestimate is likely offset by EPA’s use of the higher cost of the difficult retrofit cost 

category. EPA does not have additional data upon which to base different costs, nor did 

commenters provide any. Further, EPA has concluded that this would not have changed the 

outcome of EPA’s evaluation of closed-cycle cooling as BTA since costs were not dispositive. 

EPA notes that the impact on the national costs is limited since smaller systems only comprise 20 

Essay 21 245 
percent of total manufacturing closed-cycle system design flow. In other words, even a modest 

increase in capital costs for low flow manufacturing facilities would not have resulted in national 

total rule costs that were appreciably higher. This topic is discussed in greater detail in DCN12­

6655. 

Riverkeeper (comment 2391) argued that EPA’s Option 2 and Option 3 costs are overestimated 

by 60 percent to 70 percent. As discussed below, EPA disagrees that it has overestimated closedcycle cooling costs. Also, EPA notes that while EPA considered costs for today’s final rule, costs 

were not a dispositive factor in rejecting closed-cycle as BTA on a national basis. See Section VI 

of the preamble. Riverkeeper developed their estimates using EPA’s closed-cycle Phase II cost 

model retrofit factor applied to SPX Clear Skies cooling tower costs, adjusted for inflation, and 

adjusted for the energy penalty cited in the EPA Phase II Proposal TDD. The commenter 

assumed zero downtime costs. EPA’s position regarding each of these components is discussed 

in detail in the record (see DCN 12-6656) and summarized below. 

Closed‐Cycle Cooling for Existing Units at Generators

Riverkeeper (comment 2391) expressed concern that EPA abandoned its own closed-cycle 

estimation methodology developed under Phase II and adopted costs developed by the power 

industry and as a result overestimated costs. Riverkeeper discussed several aspects in which EPA 

overestimated costs and presented an evaluation of EPA’s closed-cycle cost estimates in an 

attachment prepared by their contactor, Powers Engineering. EPA disagrees that the revised 

closed-cycle costs are overestimated. EPA’s original Phase II cooling tower cost estimation 

methodology relied upon vendor quotes and BPJ engineering assumptions from new 

construction. The approach did not include any data from actual project estimates. EPA now has 

better cost data, including the EPRI cost models based on actual facility-specific retrofit costs. 

EPA included this data in its methodology for developing the final rule costs. EPA continues to 

receive critical comments from industry (including EPRI) that the closed-cycle costs are 

underestimated despite the fact that EPA relied upon basic elements of the cost estimation 

methodology provide by industry and EPRI. A comparison of hypothetical capital costs cited by 

Riverkeeper and actual cost data for more recent closed-cycle retrofit projects supports EPA’s 

position that its estimate is a reasonable approximation of the range of costs that may be incurred 

nationwide. A more detailed analysis and discussion of this issue and the Powers Engineering 

comments can be found at DCN 12-6656. 

Riverkeeper (comment 2391) also stated that EPA’s reasoning on closed-cycle retrofit downtime 

is contradicted by the record. They state that EPA overestimated construction downtime for 

closed-cycle retrofits for fossil-fuel facilities by a factor of two in the 2002 Phase II TDD. The 

comment asserts EPA repeats the overestimate in the March 2011 existing facilities rule proposal 

TDD when EPA continued to assume a two month (8 week) total downtime and a net downtime 

of one month (4 week). EPA agrees with this commenter that, at some facilities, a retrofit can be 

implemented with little difficulty, the tie-in can be performed during a typical facility annual or 

18 month scheduled maintenance period (which based on site visits, EPA estimates are 4 weeks 

on average), and that for these cases there would be no net downtime. However, for facilities 

where retrofit difficulties may be encountered the downtime duration may be much longer. For 

example, new data obtained by EPA indicate that 6-8 weeks total downtime was required for the 

Yates and McDonough retrofits which represent average to difficult retrofits. Also, EPA’s 

Essay 21 246 
                                                            

 

 

analysis of the EPRI downtime estimates for generators resulted in a weighted average of 1.5 

months net downtime which is equivalent to a net downtime of 6 weeks which is longer than the 

4 weeks assumed by EPA.43 EPA notes that there is limited information available upon which to 

base this estimate but concluded that the eight week total downtime estimate is reasonable and 

still supported by the record. See DCN 12-6656 for additional discussion. See Essay 35 for 

detailed discussion of installation downtime. 

Riverkeeper (comment 2391) also takes issue with EPA’s increase in the estimated construction 

downtime from 2 months to 7 months between 2002 and 2011 for nuclear facilities. Based on 

data regarding recent nuclear generating system upgrades, Riverkeeper states that the additional 

outage should be no longer than 2 months. In response to comments received since proposal and 

upon evaluation of additional data, EPA has revised the downtime estimates for closed-cycle 

retrofits at nuclear facilities in a way that substantially reduces the overall downtime estimate to 

an aggregate value similar to that suggested by Riverkeeper. In the revised approach, facilities 

are divided into two groups: those that have conducted or are currently planning to conduct an 

extended capacity uprate (ECU) and those that have not. An important characteristic of an ECU 

is that it involves considerably more construction activities compared to simple refueling outages 

(including replacement of portions of the generating system) and therefore involves outages 

much longer than those for refueling. These projects provide an ideal opportunity to further 

reduce downtime if the closed-cycle retrofit is performed concurrently. Data regarding ECU 

scheduling was readily available and revisions to the final rule have given the Director greater 

flexibility in establishing compliance schedules for entrainment requirements would allow for 

scheduling of the closed-cycle retrofit to occur concurrently with an ECU. For those facilities 

where ECUs are unlikely to occur in the future (i.e., facilities where an ECU has been performed 

or is currently planned), EPA took a more conservative approach similar to the approach used at 

proposal but with the duration adjusted downward to a level consistent with new information. At 

proposal, EPA used the 7-month (28-week) closed-cycle retrofit outage for all nuclear facilities 

on the Phase II NODA estimate which was based on the only nuclear closed-cycle retrofit 

actually performed at an existing nuclear facility (Palisades) in the 1970s. For the revised final 

rule estimate, EPA evaluated the EPRI net downtime estimate of 6 months used in their cost 

estimate (EPRI Report Number 1022491, provided as an attachment to EPRI’s comments on the 

proposed rule; see EPA-HQ-OW-2008-0667-2200). In support of the 6-month estimate, EPRI 

cited engineering estimates for four nuclear power plants that ranged from 5 to 22 months and 

noted that the expected downtime was difficult to predict since there was a great degree of 

uncertainty given the lack of actual data. A closed-cycle retrofit for these facilities that will not 

conduct an ECU would likely occur concurrently with a refueling outage which now typically 

takes about 4 to 6 weeks (see DCN 12-6876). Thus, the EPRI net downtime estimate of 6 months 

or 24 weeks would be consistent with a total retrofit downtime of about 28 weeks. EPA notes 

that this 28-week value is consistent with the duration of the first steam generator replacement 

project for SONGs Unit 244 and while this outage length is the higher of the two similar projects 

at SONGS, the difference demonstrates that complex projects for which contractors and 

engineers have little previous experience will tend to take longer. The actual duration of the 

43 The EPRI estimates which ranged from 0 to 6 months were used to derive energy replacement costs and given that
 

easy retrofits were assigned 0 months these values clearly reflect net downtime. 44 The first attempt at replacement of the steam generator for SONGS unit 2 took 28 weeks but a similar subsequent 

project for unit 3 was expected to be shorter (see DCN 10-6548). 

Essay 21 247 
                                                            

 

 

outage required for a nuclear closed-cycle retrofit is still unknown and will be influenced by sitespecific factors. Given this uncertainty, EPA concluded that a 24-week estimate was reasonable 

and applied this value in the economic analysis. 

For the remainder of facilities that are likely to conduct an ECU in the future, EPA estimates that 

under favorable conditions, ECUs typically have a duration of two to four months (see DCN 12­

6875) but can also take much longer.45 For this analysis, EPA assumed that facilities performing 

an ECU would be capable of completing the retrofit concurrently with the ECU and that the 

scope of the ECU would be extensive enough to push the duration toward the longer end of the 2 

to 4 month or longer range. For these projects, EPA assumed zero downtime which is actually a 

shorter duration than the 2 months suggested by Riverkeeper. See the Economic Analysis for 

Final 316(b) Existing Facilities Rule for more details regarding the application. See also DCN 

12-6656. Based on data from the NRC, EPA estimates that roughly one-third of existing nuclear 

generating units have already performed or have applied for an ECU and therefore are assumed 

the a 24-week downtime. As a result, the equivalent average net downtime across all nuclear 

units should be about 8 weeks (2 months). Thus, while the 24-week estimate is still longer than 

Riverkeeper’s suggested length, EPA has adjusted the overall nuclear closed-cycle retrofit 

downtime to a value that is consistent with Riverkeeper’s position. 

Moreover, to the extent that Riverkeeper comments stating that EPA may have overestimated 

closed-cycle cooling retrofit costs, EPA also would stress that its decision about what national 

standards for impingement and entrainment to promulgate took a variety of factors into 

consideration in addition to the costs. In deciding on its final regulatory option (and in 

rejecting closed-cycle as BTA), cost was not a dispositive factor. See Section VI.E of the 

final preamble for additional discussion. 

Several commenters stated that EPA did not include costs of blowdown treatment particularly if 

high cycles of concentration (COC) are required. The final rule does not include a requirement to 

meet a specified COC in order to meet the definition of closed-cycle cooling and thus the high 

COC requirement cited are not relevant. See Essay 17A. However, regarding cost of blowdown 

treatment, EPA agrees that there is no separate cost element for blowdown treatment in the cost 

methodology used but disagrees that such costs are not included. EPA notes that its costs include 

actual costs for the entire closed-cycle retrofit project as estimated by EPRI. Since the costs are 

total project costs, the data includes blowdown treatment component costs anytime the specific 

facility found such costs to be necessary. This presumption is supported in documentation of the 

most recent EPRI cost estimate which uses the same model approach (see EPRI Report 1022491) 

and provides similar costs as EPA’s (see DCN 12-6656). The EPRI report specifically discusses 

the need for considerations for “water treatment and other maintenance facilities for the 

treatment of cooling tower makeup and blowdown, if required.” The EPRI report also states that 

“water treatment may be required for discharge of cooling tower blowdown” when discussing 

the basis for O&M costs used in the model. Thus, EPA concluded that it is reasonable to assume 

that blowdown treatment costs are already included in the EPA model. Also, as explained above, 

high COCs or flow reductions of 97.5 percent or 94.9 percent depending on the water salinity are 

45 Riverkeeper provided examples of ECU-type activities suggesting that a 75 day (10 week) duration which is in 

agreement with a 2 to 4 week duration cited by engineers (see DCN 12-6875) but there are instances where the 

duration was much longer. For example, Turkey Point took 5 months and SONGS unit 2 took 28 weeks. 

Essay 21 248 
not requirements to meet the definition of closed-cycle, but rather serve as examples as to what 

comprises a properly operated cooling tower with minimized makeup flows. 

One commenter stated that EPA did not consider that some existing closed-cycle systems may 

incur increased tower maintenance chemical and blowdown treatment costs due to unspecified 

permit application requirements and certain impingement mortality requirements (e.g., lower 

velocity, flow for fish returns, blockage reduction). EPA has revised the final rule to provide an 

IM compliance alternative for facilities with closed-cycle recirculating systems. Therefore, no 

additional costs will result. Commenters provided no explanation or examples of how such 

requirements would result in increased chemical and blowdown treatment costs. 

Commenters noted that the EPRI costs for the electric generating facilities covered in proposal 

Options 2 and 3 are about 50 percent higher than the EPA estimates at proposal for electric 

generators. EPA notes that these EPRI estimates are based on the methodology described in 

EPRI Technical Report 1022491. EPA conducted a comparison of the EPA and EPRI cost 

methodologies and concluded that the national level capital costs were within 11 percent, which 

corresponds to less than 1 percent change in annualized costs of the rule at a 7 percent interest 

rate. EPA notes a major component contributing to the higher EPRI total costs is the increased 

downtime associated with EPRI’s inclusion of cooling system re-optimization. As discussed in 

DCN 12-6656, EPA concludes that by factoring in only the higher downtime costs and reduced 

auxiliary power costs, EPRI failed to also incorporate other cost benefits of re-optimization that 

would have resulting reductions in long term costs that favor selection of re-optimization. EPA 

notes that re-optimization (which involves improvements to the condenser performance as well 

as use of an overall smaller cooling system) will have additional benefits of reduced heat rate 

penalty and reduced O&M costs beyond just the auxiliary power requirements; these were not 

addressed in the EPRI methodology. 

EPRI presented a detailed closed-cycle retrofit cost analysis for Phase II facilities in EPRI 

Technical Report 1022491. This document was one of many submitted by EPRI that were 

described as either directly supporting their comments or which they believed EPA would find of 

use as part of developing the final Existing Facilities Rule. EPA welcomes this data and notes 

that EPA’s final closed-cycle cost methodology is based on an earlier cost estimation approach 

originally provided by EPRI. EPRI’s previous cost methodology data submissions did not come 

with any actual facility or industry-wide estimates. The cited report included additional 

refinements to their methodology including some actual industry-wide (Phase II facility) cost 

estimates. EPA conducted a detailed analysis that compared the EPRI methodology and results 

of the model presented in the EPRI Technical Report 1022491 to the EPA model used in the 

final rule (see DCN 12-6656). This comparison evaluated how well the results of the application 

of the EPRI closed-cycle cost estimation methodology (with recent refinements) compared to the 

results of EPA’s final rule methodology and whether any changes to the EPA methodology were 

warranted based on this new information. The EPRI report did not address O&M outside of 

energy requirements. The analysis concludes that the EPA and EPRI capital costs are similar in 

magnitude with the EPA costs being about 13 percent lower than the EPRI costs. Though the 

new EPRI capital costs are somewhat higher, they are based on detailed site-specific information 

that was not made available to EPA. As discussed above, EPA finds that the capital costs are 

close enough that when the costs are annualized there are no changes necessary. EPA notes such 

Essay 21 249 
changes would not even be possible without EPRI’s more detailed site-specific information. See 

DCN 12-6656 for the detailed analysis. 

The Utility Water Act Group (UWAG) (comment 2210) noted that EPA’s approach to estimated 

closed-cycle cooling costs includes a variety of assumptions, and that EPA seems to have made 

little effort to ground-truth its hypothetical cost equations against real costs experienced by real 

facilities or detailed estimates prepared by operators or their consultants. UWAG gives several 

examples of facilities where costs would be higher than EPA estimates. EPA agrees that for 

some facilities the actual costs will be higher than the EPA estimate, but notes the cost curves 

generated by EPRI suggests that UWAG has deliberately selected only the higher costs estimates 

as their examples. UWAG did not provide cost data for all of the facilities, include any low cost 

facilities, and the provided examples were never examples of “easy” retrofits. In calculating the 

national estimates, since EPA did not have the information to determine whether any specific 

installation would be easy, average, or difficult, EPA chose to apply cost estimates for average 

difficulty cooling tower retrofits in recognition that some actual costs would be higher and some 

would be lower and that these costs would balance out in the overall national estimate. EPRI 

Technical Report 1022491 includes a ground-truth comparison of their recent estimated capital 

costs to actual and detailed engineering estimates for nine facilities. One nuclear plant designated 

as an extremely difficult retrofit reported costs over 50 percent higher than the EPRI estimate. 

The aggregate of the remaining eight was within 4 percent. Since the EPA estimates resulted in 

similar total costs to those of EPRI, EPA has concluded that its costs are representative of actual 

costs when viewed on a national basis. 

Midwest Generation, Edison Mission Energy, LLC (comment 2245) states that both the EPA and 

EPRI closed-cycle estimates are underestimated because they did not include: 1) the cost of 

increased maintenance, including increased labor and chemical costs, necessary to operate 

closed-cycle cooling systems; 2) the cost to finance the capital project of installing closed-cycle 

cooling systems; 3) permitting costs required to permit closed-cycle cooling system installation 

and operation; 4) the cost of electrical system upgrades necessary due to unit retirement, energy 

replacement, and efficiency loss; and 5) the cost of environmental impacts that result from 

closed-cycle cooling systems. EPA notes that the EPA cost estimates include O&M costs, 

auxiliary energy costs, heat rate energy penalty costs, and construction downtime costs. The 

EPRI capital cost model upon which EPA based its estimates uses both actual and industry 

estimated closed-cycle cooling retrofit projects which are often expressed as total project costs. 

EPRI Technical Report 1022491 specifically notes that it does not include permitting, financing, 

or electrical system upgrade costs. Regarding permitting costs, EPRI states that “Permitting 

costs, while potentially significant, are highly site-specific, and there is no obvious method for 

generalizing them.” EPA concurs with this assessment. EPA did include a permitting costs 

component in the economic analysis, noting these costs were not necessarily specific to cooling 

towers. Further the EPA economic analysis does account for financing costs via present value 

and annualization. The 7 percent discount rate (used in the private analysis, and as one of the 

alternative discount rates for the social cost analysis) reflects long-term, real cost of capital, 

based on OMB guidance and various studies. EPA assumes the electrical upgrade comment is 

referring to the costs of possible electric distribution system modifications. In assessing whether 

the rule constitutes a “significant energy action” under Executive Order 13211, EPA concluded 

that the rule would not result in increases in the cost of energy distribution in excess of one 

percent. With regard to environmental impacts, the only environmental impacts that would result 

Essay 21 250 
in costs rather than benefits are for an increase in air emissions due to increased fuel use to 

compensate for the heat rate penalty and auxiliary energy requirements. In some locations, the 

net air emissions would decrease as the older, less efficient units are closed under a closed-cycle 

requirement. Newer, more efficient facilities would be constructed to make up the lost power 

production. Thus, the long term impacts may be minimal. While EPA did not specifically 

quantify the costs of such air emissions, EPA did consider air emissions and the potential impact 

of increased air emissions is one of the three factors EPA considered in deciding to require 

entrainment requirements on a site-specific basis. Also, to the extent that these costs can assessed 

on a site-specific basis, these costs can be included in the evaluation required as part of the sitespecific permit application requirements. See preamble for a more detailed discussion. 

One commenter, Duke Energy (comment 2215), in support of requiring site-specific 

determination of entrainment requirements stated that EPA’s closed-cycle costs are flawed and 

that EPA’s cost estimates may understate the costs by 5 to 18 times. EPA notes that the final rule 

requires establishment of entrainment requirements on a site-specific basis as requested by the 

commenter. EPA disagrees with the commenter’s assertion regarding costs, noting the basis of 

comparison provided by the commenter consists of cooling tower costs based on the Phase 1 new 

facility cooling tower model. The Phase I new facility costs were then compared to the costs of 

the closed-cycle cooling system for one of their new generating facilities. EPA notes that this 

argument is flawed in several obvious respects. First, a comparison of Phase I model costs is 

irrelevant because there is a significant difference in the cost components considered and 

construction requirements between existing system retrofits and new systems, and that EPA need 

only consider incremental costs. The result is higher net costs for retrofit systems. Second, as 

discussed above the costing methodology for this final rule is different from that used in the 

Phase I rule. In this rule EPA was able to use real world data obtained from EPRI. And third, the 

Phase I model costs are net costs that include discounts for offsetting once-through system costs 

which would otherwise need to be built at a Phase I facility. Existing facilities already have 

intake structures, pumps, condensers, and other elements of a cooling water system. 

Closed‐Cycle Cooling for Existing Intakes at Manufacturers

The American Chemistry Council (ACC) (comment 2207) provided a detailed closed-cycle cost 

estimate for retrofitting small (5,000 gpm), medium (20,000 gpm), and large (100,000 gpm) 

cooling towers. These estimates were developed to support their argument against Proposal 

Options 2 and 3 as being too costly. However, elsewhere in the comment they state that “The 

potential cost per gallon of complying with the CWIS proposed rule is much greater for smaller 

intake structures because many of the compliance costs do not vary substantially with intake 

flow.” This comment shares a common element with many other commenters who argued that 

manufacturers are different and it is not appropriate to simply transfer costs from the larger 

generating facilities to smaller manufacturing facilities. With respect to general comments that 

power plants and manufacturers are completely different, EPA disagrees. See TDD for detailed 

discussion of intake structures and technologies in use by both power plants and manufacturers. 

See Essay 14 discussion regarding many manufacturers only withdraw cooling water for 

purposes of power production. Also see Essay 14 regarding contact versus non-contact cooling 

water. 

Essay 21 251 
                                                            

 

Assuming ACC closed-cycle costs at the smaller 5,000 gpm facilities are representative, the 

resulting effect on national level cost estimates is insignificant. EPA evaluated the ACC cooling 

tower costs estimates and compared them to similar costs derived using the EPA cost model. See 

DCN 12-6655 for a detailed analysis and discussion. This analysis confirms that for medium and 

larger cooling systems, EPA’s capital and O&M costs are mostly in agreement with the ACC 

estimates. In fact, EPA’s capital costs are slightly higher for larger systems. The same is not true 

for smaller 5,000 gpm systems and the differences suggest that the EPRI (and EPA) approach 

using linear cost equations may have limitations when estimating costs for smaller systems 

where the effects of economies of scale are more pronounced. On an individual facility basis, the 

potential underestimation of smaller system costs can be significant but on a national industrywide level, the impact is small since the larger systems comprise the majority of the total noncontact cooling water flow. For manufacturing intakes currently operating as once-through, an 

estimated 80 percent of total industry-wide manufacturing facility closed-cycle cooling costs 

under Proposed Option 2 were based on estimated non-contact cooling water flow associated 

with larger systems.46 Moreover, the final rule does not require any facility (small, medium, or 

large manufacturer, or generator) to comply with IM and E requirements based on closed-cycle 

cooling. Rather, as explained above, the final rule requires a site-specific determination of 

entrainment requirements under a specified framework. As such, in the site-specific entrainment 

consideration, facilities that are less than 5,000 gpm will be able to provide site-specific costs 

that may be different than those EPA calculated for this final rule. 

It is also important to note that EPA may have overestimated closed-cycle retrofit cooling 

technology costs for Proposal Options 2 and 3 for manufacturing facilities on an industry-wide 

basis. The reason is that EPA used estimated non-contact cooling water flow rates based on 

industry-specific estimates of the proportion of DIF that is non-contact cooling water. This may 

represent an overestimation of the flow that would have ultimately been retrofitted as closedcycle since some manufacturing facilities have opportunities to reduce all or a portion of the 

volume of cooling water flow by reusing the non-contact cooling water as process water at 

significantly lower overall costs. EPA lacks the data to conduct a more refined analysis 

addressing this cost overestimate. Further, this option is generally not available to power plants 

which use a significantly smaller quantity of process water compared to cooling water. However, 

since total costs were not a reason for rejecting closed-cycle cooling as BTA, the potential 

overestimate is no longer relevant with respect to the national BTA entrainment determination. 

New Unit Costs

EPA received one comment concerning new unit costs from the United States Steel Corporation 

stating that for closed-cycle cooling costs for new units the economic “analysis should include 

secondary costs associated with treatment, emissions, and energy use.” EPA disagrees with the 

detailed comment; EPA’s costs and economic analysis need only reflect the incremental costs for 

complying with rule requirements. Other costs associated with other upgrades, construction, or 

projects are not a cost of this rule. EPA agrees that certain secondary costs should be considered. 

For new units, EPA has already included net O&M costs for treatment chemicals, energy 

requirements, and labor/materials. With regard to emissions, the commenter made reference to 

46 In this case, larger systems are defined as those with a non-contact cooling flow over 20,000 gpm which was 

chosen for illustrative purposes because it was the middle (medium size) flow value used in the ACC estimates. See 

DCN 12-6655. 

Essay 21 252 
permit modifications for air emissions and cooling tower blowdown, but did not provide any 

details regarding what these costs should include or their magnitude. Also, as noted above EPA 

has concluded that blowdown treatment is included in the cost estimates for retrofitting existing 

units which also serves as the basis for the new unit costs. See Essay 20 for more information 

regarding new units. 

Other Cost Comments

Southern Company (comment 2190) stated that EPA did not include capital costs for upgrades at 

their Daniel Plant which receives water from a cooling pond owned by an independent supplier. 

EPA agrees that no costs are included for this facility because the facility reported it withdrew 

water for cooling from an independent supplier. Southern Company presumes that they would be 

responsible for ensuring compliance of the independent supplier’s intakes that fed the cooling 

pond and states that leaving compliance up to a third party is unacceptable. They conclude that 

the alternative scenario is that the facilities will need to build a new intake if EPA does not 

“grandfather” such independent supplier arrangements. Due to the fact that facilities that receive 

cooling water from the independent supplier were not required to complete a technical survey, 

EPA did not have the data necessary at proposal to determine whether they would be in 

compliance nor estimate the cost of compliance. However, EPA notes that information supplied 

in the comment further indicates that Daniel uses a cooling pond (owned by an independent 

supplier) and that EPA’s final rule position regarding cooling ponds has changed such that many 

cooling impoundments (ponds) may meet the definition of closed-cycle cooling provided the 

makeup water withdrawal supplying water to the impoundment is minimized. While no further 

information is provided by the commenter concerning the intake technology or cooling system, 

the information provided indicates that this facility may already meet the final rule compliance 

requirements. In the final rule, EPA has not revised its position regarding applicability to 

independent suppliers and concluded this provision will have only limited applicability and 

therefore only a minimal impact on a national basis. EPA expects that the independent supplier 

scenario described by the commenter is addressed at 40 CFR 125.91(b). See Section I of the 

preamble for more discussion of this issue, as well as Essay 14. 

One commenter states that a lab technician and an environmental scientist would cost a 

minimum of $100,000 per employee in costs per year including benefits and salary. EPA 

generally agrees with the annual salary rate noting that EPA’s economic impact estimate 

regarding monitoring costs use similar costs including a loaded dollar/hr cost of $46/hr for a 

biologist and $31/hr for a biological technician; these are equivalent to annual salaries of 

$96,000 and $64,000, respectively. 

Other commenters provided total cost estimates using general descriptions of what the costs 

represented. EPA is unable to respond to the generalized total cost estimates cited in the 

comments since these commenters failed to provide supporting documentation describing the 

source or basis of the cost estimate. Without such supporting documentation, EPA is unable to 

determine the scope and comparability of the cost estimates. 

Essay 21 253 
Essay 22: Implementation

Introduction

In the proposed rule, EPA considered a variety of options to implement the requirements it 

proposed to establish under section 316(b) of the Clean Water Act (CWA) for existing power 

generating and manufacturing and industrial facilities that withdraw water from waters of the 

U.S. exclusively for cooling purposes. EPA’s preferred option would have allowed facilities to 

select any technology that achieved the IM numeric performance standard, or alternatively to 

demonstrate that intake velocity was less than 0.5 fps. EPA subsequently published a NODA that 

discussed additional approaches to implement 316(b) CWA requirements on a national basis. 

This essay addresses comments relaying support for, suggesting modifications to, and 

disagreeing with EPA’s options for complying with the BTA standards and the associated 

requirements for implementing them. Commenters also responded to EPA’s request for comment 

on a variety of topics. The majority of commenters (generally, these were industry and State 

resource agency stakeholders) expressed concerns about the administrative burden and technical 

and logistical constraints in complying with the proposed NPDES permit applications 

requirements, timelines for submittals, and monitoring and reporting requirements. Many 

commenters urged EPA to streamline permit application and monitoring requirements, 

particularly for facilities that plan to operate or are already operating CCRSs and/or any other 

technology deemed to be BTA. Many of these commenters expressed particular support of the 

possible rule revisions discussed in the NODAs, noting the flexibility and site-specific 

approaches provided in the possible revisions. Some commenters (State resource agencies) 

generally favored site-specific discretion being granted to the permitting authority for 

impingement mortality limitations and monitoring requirements, while also expressing concern 

about the resources needed to establish site-specific entrainment mortality requirements for 

applicable facilities in the absence of prescribed technical requirement. Many commenters asked 

for clarification on specific approaches and issues. Some commenters (generally, these were 

environmental organizations) supported more extensive data gathering and submissions for 

NPDES permit application and minimum monitoring and reporting requirements. 

In today’s final rule, EPA establishes a standard for minimizing impingement mortality, and 

provides seven different compliance alternatives to achieve the BTA standard. EPA has 

reevaluated and revised the criteria it adopted for demonstrating compliance with this standard 

and the compliance alternatives; see Essays 16 and 16A. EPA has streamlined and simplified the 

permit application and monitoring requirements, including harmonizing the permit application 

and compliance deadlines for impingement mortality and entrainment mortality to allow for 

comprehensive, site-specific requirements to be established at each facility; see preamble Section 

VIII. The national BTA standard for entrainment requires that entrainment reductions measure 

will be determined on a site-specific basis, using information provided to the Director in the 

facility’s NPDES permit application. 

General Implementation

The final rule impingement mortality standard and provides seven compliance alternatives 

allowing each entity affected by this rule to determine the compliance option and technology or 

Essay 22 254 
systems of technologies that are most appropriate for that particular facility, or alternatively for 

each cooling water intake structure at the facility. The rule does not require implementation of 

any particular technology, though it does provide specific alternatives that streamline compliance 

when using any technology that EPA’s record shows will consistently and reliably meet the 

impingement mortality BTA requirements, including closed-cycle recirculating systems, low 

intake velocity, offshore velocity caps, and modified traveling screens. See Essay 16. 

Many commenters were concerned that the proposed permit application and supporting 

information requirements were unworkable, overly burdensome, and unclear, particularly those 

relating to permit application deadlines, peer review, and entrainment studies. As outlined in the 

preamble to today’s rule, EPA has clarified the timeframe for compliance deadlines and 

simplified the permit application and supporting information requirements. EPA has concluded 

that these schedules and the flexibility allowed to the Director in requiring permit application 

materials are reasonable and will not force facilities into noncompliance. See preamble Section 

VIII for more information. 

Short‐Term Exceedances

A few commenters requested that EPA add an exception to the proposed velocity standard for 

“short-term” exceedance periods of no longer than 24 hours, due to unusual weather conditions, 

facility malfunctions, or required maintenance (e.g., backwash conditions). Several commenters 

called for the inclusion of a provision that certain conditions (e.g., extreme weather events) 

constitute an affirmative defense to claims of noncompliance with rule requirements. EPA agrees 

that the Director should have the authority over short-term velocity exceedances if a facility 

elects to comply via a low velocity compliance alternative. The rule explicitly states that the 

Director may authorize the facility to exceed 0.5 fps at an intake for brief periods for the purpose 

of maintaining the cooling water intake system, such as backwashing the screen face. EPA 

expects the Director already has enforcement discretion for short-term velocity exceedances 

related to exceptional events, such as operational upsets, malfunctions, or emergencies. Shortterm or emergency conditions should not affect a facility’s ability to comply with the 

impingement mortality standard, and such conditions should not interfere with overall optimized 

performance of impingement minimization technology or performance of a suite of technologies. 

Ultimately, the Director has discretion to determine the appropriate enforcement response for 

each situation in the face of exceptional or extreme events. See Essay 17 for further discussion in 

handling short-term exceedances. 

Similarly, several commenters requested inclusion of a provision providing exemption for 

emergency CWISs from the applicable impingement mortality standards at 40 CFR 125.94, 

applicable to facilities that have installed passive intake technologies. First, EPA notes that 

today’s final rule does not apply to any quantity of emergency back-up water flows. See 40 CFR 

125.94(c)(3)(iv). With respect to passive intake technologies such as wedgewire screens, barrier 

nets, or porous dikes, EPA understands they may be subject to clogging due to icing, aquatic 

plants, or damage from other uncontrollable environmental conditions. EPA does not expect this 

provision would be necessary to address such situations. As described in more detail in Essay 18, 

every viable manufacturing facility has adapted to ensure an available supply of cooling water, 

and further every power plant has taken the measure necessary to ensure condenser pipes remain 

open and free so that the facilities can function. Facilities that fail to make these adjustments are 

Essay 22 255 
not able to offer reliable power, steam, or manufactured products. While EPA is aware these can 

be a concern, EPA’s record demonstrates that facilities have developed approaches that 

overcome clogging. EPA encourages technology transfer and sharing of information between 

facilities, so that all facilities can establish the most cost-effective compliance path available. 

Also, EPA expects that the vast majority of facilities that employ wedgewire screens will comply 

with the IM standard because the screens will achieve the pre-approved low velocity 

requirements under the IM standard compliance alternatives at 40 CFR 125.94(c)(2) and (3). In 

cases where facilities comply with the IM standard via the low design velocity, this would not be 

an issue as facilities are not required to monitor their velocity. In cases where facilities comply 

with the IM standard via actual velocity, the rule allows the Director to authorize temporary 

exceedances to maintain the CWIS. 

Application to Each Intake

Many commenters requested that regulatory agencies have the flexibility to address impingement 

and entrainment mortality requirements on a facility-wide basis rather than addressing 

requirements in the same manner at each intake structure. EPA agrees that the proposed rule was 

unclear regarding the whether specific provisions apply to the entire facility or to individual 

intakes. To clarify this issue, EPA modified the final rule language so as to state clearly that a 

facility with multiple intakes must decide whether it will adopt a single compliance strategy for 

impingement mortality for the entire facility or adopt an intake-specific compliance strategy at 

each cooling water intake. Thus, EPA has created flexibility for facilities with multiple intakes to 

select different compliance strategies for each intake. Regardless of which impingement 

compliance approach a facility chooses (single strategy for entire facility or different strategies 

for different intakes), if the facility chooses to comply with the impingement standard by 

operating at a maximum through-screen velocity of 0.5 feet per second, the facility must measure 

and comply with the velocity alternative on an individual intake basis. 

One commenter also requested that the AIF (25 percent cooling water criterion) threshold and 

applicable requirements be determined on an intake-by-intake basis. EPA already considered this 

issue in Phase I and Phase II, and did not receive any new information that would result in a 

different approach here. See Essay 14 for a more detailed response to this issue. 

Compliance Deadlines and Implementation Schedules

NPDES Permit Application Cycle

EPA received many comments concerning the permitting schedule and deadlines for permit 

application submittals. Many commenters thought that the proposed timelines for submittals 

were unreasonably short, while some felt the timeline was too long. Commenters suggested that 

EPA allow appropriate degree of flexibility and longer timeframes for permit application 

submittal, such as tying permit application requirements to the NPDES permit renewal cycle to 

stagger implementation of the regulation. They stated that this approach would help address 

resource concerns for implementing the regulation at all facilities on the same timeframe. Several 

commenters were also concerned about the burden of coordinated compliance efforts for 

multiple rules. Commenters, including Riverkeeper, expressed concerns about time and resource 

constraints for both permitting authorities and entities subject to the final rule, particularly with 

respect to the detailed technical and cost-benefit studies required to evaluate entrainment. They 

Essay 22 256 
noted that permitting authorities have limited time to review and provide comment on permit 

applications that are expected to be submitted in the same timeframe and limited resources to 

consult technical experts to support this effort. One commenter was concerned that State 

permitting authorities lack the resources and expertise for case-by-case permitting 

determinations. In addition, there was concern about limited availability of technical experts 

qualified to review permit application materials. Similarly, facilities subject to the same rule 

timeframes would overwhelm the limited stock of qualified technical experts available to support 

the development of required permit application materials and the manufacturers of BTA 

technologies. Other commenters, including Riverkeeper, were concerned that the proposed 

implementation schedule was already unreasonably long and that facilities should be required to 

come into compliance in half the time proposed; they stated that three years should be sufficient 

for impingement mortality compliance and eight years for entrainment compliance. Riverkeeper 

also stated that a retrofit to closed-cycle cooling should generally take only three years. Other 

commenters, including Riverkeeper, stated that facilities had already completed much of the 

documentation that comprises the permit application materials and should therefore be subject to 

an accelerated compliance schedule. 

Because IM and EM compliance requirements were proposed to be developed on different 

tracks, commenters were concerned that facilities subject to both IM and EM requirements might 

begin installation of redundant or ineffective technology for meeting both sets of requirements. 

Commenters requested that EPA harmonize permit application and compliance deadlines for IM 

and EM to allow for comprehensive, site-specific requirements to be established at each facility 

so that impingement controls are not needlessly or prematurely installed. 

As outlined in the preamble to today’s rule, EPA has clarified and revised the timeframe for 

compliance deadlines. EPA agrees with the concerns of many commenters regarding compliance 

deadlines and has tied the permit application materials submittal deadlines for existing facilities 

to the NPDES permit renewal cycle. EPA realizes that, in some cases, a facility may already be 

in the middle of a permit proceeding at the time of promulgation of this rule, or the Director may 

have already required much of the same information be submitted by the facility prior 

promulgation of today’s final rule. Therefore, the rule includes several provisions that provide 

flexibility for the permit application requirements. In the case of permit proceedings begun prior 

to the effective date of today’s rule, and issued prior to December 31, 2016, the Director may 

proceed with any determination of BTA standards for impingement mortality and entrainment 

without requiring all of the permit application requirements of 40 CFR 122.21(r). See 40 CFR 

125.94(a)(2). In such circumstances where permit proceedings have already begun prior to the 

effective date of the rule, these facilities will still need to submit the appropriate permit 

application materials found at 40 CFR 122.21(r) permit applications during their next 

application. Additionally, while EPA expects that many facilities will already comply with 40 

CFR 125.94(c), in some cases the facility will need to choose one of the compliance alternatives 

for IM in their subsequent permit cycle. See Section VIII.A of the preamble for further 

discussion. 

Permit renewals for existing facilities and permit modifications for new units at existing facilities 

generally conform to the typical NPDES permit cycle. Existing facilities subject to the final 

316(b) regulations applying for reissuance of a permit expiring after December 31, 2016, must 

submit the information required in 40 CFR 122.21(r), in addition to all other applicable permit 

Essay 22 257 
application information, no later than 180 days before the current permit expires. The rule 

provides flexibility for the Director to waive or allow later submission of the materials required 

in 40 CFR 122.21(r) based on a showing that the facility could not develop the information by 

the time required for submission of the permit application. The Director also has the discretion to 

waive some or all of the information requirements of 40 CFR 122.21(r) if the intake is located in 

a manmade lake or reservoir, and the fisheries are stocked and managed by a State or Federal 

natural resources agency or the equivalent. Similar to a new NPDES facility, applicable 40 CFR 

122.21(r) materials for new units at existing facilities must be submitted no later than 180 days 

before the planned commencement of cooling water withdrawals for the operation of the new 

unit. EPA has determined that these schedules and the flexibility allowed to the Director in 

requiring permit application materials is reasonable and will not force facilities into 

noncompliance. 

Commenters were concerned about how other regulations affecting the energy sector will 

compound the difficulty in implementing strategies to achieve compliance with today’s final 

rule. In determining the cost of compliance with today’s rule, EPA considered the cost of 

compliance with multiple rules. The flexible approach in today’s rule allows the Director to 

consider other regulatory constraints when establishing the facility’s site-specific compliance 

schedule. EPA notes that, in some cases, efforts made to achieve compliance with multiple rules 

could be coordinated during regularly scheduled plant outages or downtime. See Essay 29 for 

further discussion of the cumulative impact of EPA regulations. 

Harmonizing IM and EM Requirements and the Compliance Timeline

EPA further modified the proposed compliance deadlines for impingement mortality and 

entrainment requirements by aligning them. A facility subject to both impingement mortality and 

entrainment standards must comply with BTA standards for impingement mortality and its 

entrainment requirements as soon as practicable after issuance of its final permit establishing 

applicable entrainment requirements. New units at an existing facility must comply with 

applicable BTA standards with respect to the new unit upon commencement of the new unit’s 

operation. Though the regulation does not address the concept of “additional time,” EPA 

acknowledges that there may be overlap in the technologies used to comply with impingement 

mortality and entrainment standards, which could result in the facility needing more time to 

comply with the impingement mortality requirements. For example, if a facility plans to retrofit 

to wet cooling towers to reduce entrainment, the wet cooling towers technology also meets the 

requirements for impingement mortality via 40 CFR 125.94(c)(1). EPA therefore concluded that 

most facilities would not have an entrainment determination completed early enough to impose a 

3-year compliance deadline on all impingement technology responses. As such, the Director 

would schedule compliance with the impingement mortality requirements to match the schedule 

for entrainment requirements. EPA does expect, however, that facilities where modified traveling 

screens are determined to be BTA should not take more than three years for installation and 

implementation of the technology, though technology optimization and completion and approval 

of the 2-year performance optimization study would necessarily take a longer period. For 

facilities that choose to comply with the IM standards via the low velocity compliance 

alternative, have existing offshore velocity caps, or existing closed-cycle recirculating systems, 

EPA expects compliance to occur much sooner. EPA projects just over half of facilities (18 

percent of facilities choosing closed-cycle recirculating systems; 34 percent choosing velocity 

Essay 22 258 
reduction; and 1 percent choosing velocity caps) will comply with one of these alternatives 

where compliance can occur quite rapidly. 

EPA notes that some facilities (i.e., those already required to conduct certain studies under the 

2004 Phase II rule) will have already developed some of the permit application materials. 

However, not all facilities submitted these data in pervious permit applications. EPA notes that 

its estimates of administrative costs reflect this previous data collection requirement. However, 

EPA disagrees that an accelerated compliance schedule is appropriate, as the existing facility rule 

addresses facilities not covered by the 2004 Phase II rule (i.e., small power plants and all 

manufacturers) that have not been previously required to conduct any of these studies. In 

addition, under the final existing facility rule, facilities are required to submit studies that, in 

some cases, while similar to studies required under Phase II, would not have been completed 

prior to the suspension of the 2004 Phase II rule. These studies (such as the Entrainment 

Characterization Study) need to be given ample time for adequately representative sampling and 

analysis. Other studies, such as the Benefits Valuation Study, are largely comprised of material 

that was not collected or analyzed under Phase II; in these cases, there is clearly no way to 

accelerate the schedule for submission of these materials. EPA also disagrees that most facilities 

have completed detailed studies for converting to closed-cycle cooling. While it is possible (or 

even likely) that many facilities have contemplated conceptual analyses of cost and feasibility for 

closed-cycle cooling, in EPA’s view, most facilities have not likely completed an analysis of 

sufficient detail to complete the Comprehensive Technical Feasibility and Cost Evaluation 

Study. For an entrainment determination (especially one requiring a facility to retrofit to a 

closed-cycle recirculating system), EPA disagrees that compliance could occur in all cases as 

rapidly as some commenters suggest. Nuclear facilities and some manufacturing facilities faced 

with more complex retrofits could require a lengthy period of time to design, construct, and 

implement control technologies. Further, EPA intends that energy reliability be considered when 

establishing a schedule for compliance. Nuclear power plants and other baseload facilities 

serving the same region may need to have compliance staggered so as to avoid inadequate 

energy supplies and reserves. See Essay 19 regarding EPA’s expected timeline for full 

compliance. Thus, while EPA expects all facilities would comply as soon as practicable, EPA 

agrees that some of the above scenarios could, in some cases, result in a lengthy period of time 

where unacceptable levels of AEI would continue to occur. Therefore, the rule authorizes the 

Director, at 40 CFR 125.94(h), to establish interim BTA requirements in a facility’s schedule of 

requirements, for impingement mortality, entrainment, or both, where necessary on a sitespecific basis. 

One commenter expressed concern about the 10-year time-frame assumed for retrofit to closedcycle cooling used for Option 2 in the proposed rule. EPA notes that there is no fixed timeline 

specified in the final rule for making a BTA entrainment determination or installing a 

compliance technology. EPA agrees that actual implementation times will vary and notes that 

Option 2 (which was rejected) used 10 years as a preliminary estimate for the start-to-finish 

permitting and compliance process, including study submittals, review by the Director, permit 

issuance (as needed), and construction of required technologies (such as a cooling tower). See 

Essay 19 regarding EPA’s expected timeline for full compliance. 

While EPA has dropped the proposed requirement for compliance with the impingement 

mortality standards within eight years, instead requiring facilities to comply with the 

Essay 22 259 
impingement mortality and entrainment requirements as soon as practicable according to the 

schedule of requirements set by the Director, the Agency has concluded that the final rule will 

generally result in compliance along a similar seven to eight-year timeframe. The final rule 

provides the Director with the flexibility, when establishing an electric power generating 

facility’s compliance schedule, to consider issues (e.g., logistical, regulatory) concerning 

maintenance of adequate energy reliability and necessary grid reserve capacity. Similarly, the 

Director may consider extenuating circumstances in establishing a compliance schedule for a 

manufacturing facility. The example in the preamble includes establishment of a staggered 

implementation schedule for multiple facilities serving the same localities. These flexibilities 

allow the Director to consider constraints from multiple regulations when establishing the 

facility’s site-specific compliance schedule. Ultimately, all facilities will be required to follow 

their schedule as determined by the Director. 

Nuclear Facilities

Several commenters were concerned about implementation schedule of the final rule at nuclear 

facilities. They requested assurance that the compliance schedules for nuclear facilities would 

provide opportunities for consultation with the Nuclear Regulatory Commission and allow for 

alignment with Nuclear Regulatory Commission relicensing processes. EPA’s considerations of 

nuclear facilities are discussed in Essay 18. 

Consideration of Remaining Useful Plant Life

One commenter was concerned about BTA requirements for facilities utilizing once-through 

cooling that have recently been replaced and repowered. The commenter noted that premature 

replacement of some of this equipment would impact debt capitalization, power rates, and 

represent an improper use of ratepayer funds. EPA acknowledges the trade-offs inherent in 

balancing protection of fish, air quality, and remaining plant life, among other factors. As such, 

EPA structured the final rule with sufficient flexibilities as to allow the Director to determine 

compliance schedule for entrainment BTA requirements based on consideration of local factors, 

including remaining useful plant life. EPA notes that, for facilities that have or will be required 

to install closed-cycle recirculating systems, the final rule allows for harmonizing compliance 

schedules for impingement and entrainment such that facilities would not need to install 

technologies that become obsolete upon installation of the CCRS. Considering the long lead time 

to plan, design, and construct the most effective entrainment technology, closed-cycle cooling 

systems such as wet cooling towers, EPA determined that the Director should have the latitude to 

consider the remaining useful plant life in establishing entrainment requirements for a facility. 

See full discussion in Essay 19. 

Facility Retirement

Some commenters requested that facilities scheduled to retire in the near future be provided with 

additional flexibility, including waivers for permit application materials. Generally, EPA agrees 

this would not be an efficient use of a facility’s resources and has included a provision in the rule 

to allow the Director to waive some or all permit application requirements. EPA notes, however, 

that units that are repowered instead of retired may be subject to additional requirements. 

Essay 22 260 
Considering Use of New Technologies

Another commenter was concerned that alternative entrainment technologies tailored to certain 

local fish species are not yet available for implementation; therefore, utilization of these 

unproven technologies would have an uncertain outcome and might prove an unwise investment. 

EPA notes that the final rule does not require any specific technology and allows for sufficient 

flexibility in subsequent permitting proceedings to incorporate new technologies in a facility’s 

approach towards meeting BTA requirements. As new entrainment reduction technologies are 

developed and become commercially available, EPA expects that permitting authorities will 

consider these new technologies when evaluating site-specific factors in determining entrainment 

BTA. 

Permit Development and Review Resource Constraints

EPA acknowledges that significant efforts will be required by facilities and State permitting 

authorities to develop and submit and review and approve permit applications. With the 

staggered rule implementation allowed by these implementation schedules, EPA has concluded 

that the implementation schedule will not pose an unreasonable burden on contractors or 

manufacturers of BTA technologies. EPA furthermore disagrees that State permit authorities lack 

the resources and expertise to review and approve permit applications. State permit authorities 

already issue and oversee the NPDES permits in place at existing facilities, which may already 

contain BPJ 316(b) requirements. While some commenters were concerned that a site-specific 

approach would result in State permitting authorities needing to conduct case-by-case individual 

performance standard determinations, the process established in the final rule does not allow for 

unfettered case-by-case determinations. The rule instead establishes a rigorous process for 

determining BTA for entrainment for each facility based on site-specific conditions. The seven 

IM BTA compliance alternatives offer structured flexibility in determining which option is best 

for each facility. Because EPA concluded that national entrainment requirements based on a 

particular technology were not appropriate as BTA, in-scope facilities must submit extensive 

entrainment characterization studies and data. The rule outlines the process by which sitespecific determinations are made based upon these studies and data, so State permitting 

authorities will not need “reinvent the wheel” for each permit. 

EPA made an effort to ensure that information provided to the State will be checked by an 

appropriate third-party reviewer. It is EPA’s experience that a sufficient number of qualified 

contractors are available to assist facilities and State as needed. In addition, oversight authorities 

will have already reviewed studies and data previously submitted by many facilities that are 

substantially similar to the permit application requirements at 40 CFR 122.21(r). Because the 

Director has the discretion to waive some or all of the 40 CFR 122.21(r) requirements based on 

applicability of previously submitted material, the burden for both the facility and oversight 

authority in developing and reviewing those materials has the potential to be significantly 

decreased. Finally, EPA staff are available to assist in the process as needed with review and 

approval of permit applications. 

Clarifying “As Soon As Possible” and “Additional Time”

Commenters also requested clarification on the definitions of the terms used in the rule, “as soon 

as possible” and “additional time” for compliance purposes. EPA notes that the concept of “as 

Essay 22 261 
soon as possible” is one that already exists for compliance schedules in the generally applicable 

NPDES regulations at 40 CFR 122.47. The concept allows for consideration of the steps needed 

to modify or install treatment facilities, operations or other measures and the time those steps 

would take but does not presume that the permitting authority should establish a compliance 

schedule based on the maximum time period allowed. 

In contrast to the proposed rule, today’s final rule does not include a requirement for compliance 

with the impingement mortality standards within eight years. Therefore, the final regulation does 

not address the concept of “additional time.” EPA recognizes that it will take facilities time to 

upgrade existing technologies and install new technologies, and that there are limits on the 

number of facilities that can be simultaneously offline to install control technology and still 

supply goods and service to orderly, functioning markets. EPA expects the Director will take this 

into account when establishing a deadline for compliance and any such schedule would take into 

account factors provided in 40 CFR 125.98(c). EPA acknowledges that some facilities which are 

not now in a permitting proceeding may need as much as three years to fully complete their 

studies and data collection, and depending on the types of control selected, may need additional 

time to design, construct, and implement their technologies. EPA discusses the expected 

compliance timeframe in Section VIII.A of the preamble and Essay 19. 

Requiring Interim Measures

One commenter requested that the rule define interim measures to protect aquatic ecosystems to 

be implemented as NPDES permit conditions until long-term compliance solutions are in place. 

The commenter suggested that such measures could include installation of variable speed pumps 

or drives at peaking facilities or scheduling regular maintenance outages during peak spawning 

periods whenever feasible. As discussed above, the final rule clarifies that the Director has the 

authority to establish interim BTA permit requirements. Therefore EPA agrees with the 

comments that tailored measures could be required as interim measures. While today’s final rule 

does not specify interim measures to address site-specific concerns, the rule does provide the 

Director discretion to determine which interim requirements might be necessary according to 

BPJ and include those requirements in the facility’s permit. 

Cooling Water Intake Thresholds

Several commenters requested that facilities below the applicable cooling water intake thresholds 

should be considered presumptively to employ BTA for I and E and/or should not be subject to 

today’s rule unless the Director determines that the CWIS is causing adverse environmental 

impact. EPA disagrees that facilities not subject to today’s national standards are automatically 

achieving BTA I and E performance. See Essay 14 for discussion about the potential for 

impingement and entrainment at any cooling water intake threshold, and see preamble for 

discussion about cumulative impacts. Any CWIS may therefore cause unacceptable levels of 

AEI. EPA agrees that today’s rule does not apply to existing facilities with a cumulative design 

intake flow below 2 mgd or operators of new units at existing facilities with a cumulative design 

intake flow below 2 mgd. For these facilities, the Director must set appropriate requirements on a 

case-by-case basis, using best professional judgment, as required by 40 CFR 125.90(b). The 

scope of the facilities affected by today’s final rule is further discussed in Essay 14. EPA’s 

consideration of adverse environmental impacts can be found in Essay 15. 

Essay 22 262 
NPDES Permit Application Requirements

In general, commenters were concerned about the resources needed to complete the permit 

application requirements, both in the initial and subsequent permit terms. In particular, 

commenters were concerned about burdensome peer review and permit renewal requirements. In 

the case of permit renewal requirements, commenters argued that the permit renewal process 

should be streamlined as long as there were no significant changes to the facility; in such a case, 

they stated that the requirement for the 40 CFR 122.21(r) permit application studies should be 

waived and there is no need to reevaluate the BTA decision for the facility. 

EPA agrees that the proposed permit renewal process could be streamlined. As outlined in the 

preamble to today’s rule, EPA has simplified the permit re-application and supporting 

information requirements. Today’s rule allows, after the initial submission of the 40 CFR 

122.21(r) studies in accordance with the rule, that the owner or operator of a facility may, in 

subsequent permit applications, request to reduce the information required, if conditions at the 

facility and in the waterbody remain substantially unchanged since the previous application so 

long as the relevant previously submitted information remains representative of conditions at the 

facility. Substantial changes warrant a full permit application in the subsequent permitting cycle. 

For example, a species listed as threatened or endangered after issuance of the current permit 

whose range of habitat or designated critical habit includes waters where a facility intake is 

located constitutes a substantial change. Other substantial changes might include a significant 

change in the facility’s operating schedule, shifts in the local fish population, or changes in the 

quantity of water available from the source water. The owner or operator’s request must identify 

each permit application element that has not substantially changed and the basis for that 

determination. The submittal schedule for this request is specified at 40 CFR 125.95(c). Today’s 

rule grants the Director the discretion to accept or reject any part of the request. 

Peer review requirements are addressed in the preamble to the rule and later in this essay. 

Application Requirements Submittal Dates

In general, commenters (both industry and State resource agency) thought the proposed timeline 

for submittal of permit application materials was insufficient and the permit application 

requirements were onerous. Many commenters thought that EPA underestimated the time and 

effort required to gather and organize all the permit application data. Commenters were 

concerned about requirements to begin collecting permit application information before the 

publication of the final rule. Many commenters (both industry and State resource agency) 

thought that all the permit applications nation-wide being due at the same time could create an 

overwhelming administrative burden for permitting authority reviewers. Commenters were also 

concerned that that the proposed deadlines did not build in any time for permitting authority 

reviews and that the timeline would create overwhelming demand for contractor assistance. 

As discussed previously in this essay in response to comments on compliance deadlines and 

implementation schedules concerns, EPA has removed the hard deadlines from the proposed rule 

for permit application materials submittal, instead tying the submittal timeline to the NPDES 

permit renewal cycle, and creating discretion for the Director to waive or push back the deadlines 

for some or all parts of the permit application under certain circumstances. The final rule 

Essay 22 263 
provides that facilities intending to comply with the BTA standards for impingement and 

entrainment using a CCRS can choose not to provide the applicable entrainment studies. 

BTA Standard for Impingement Mortality

In general, commenters were concerned about the lack of compliance alternatives for meeting the 

IM standard, issues in conducting impingement mortality reduction studies, and the lack of data 

supporting the intake velocity requirement. Commenters also responded to EPA’s request for 

comment on monthly and annual limits on impingement mortality. Most were concerned about 

logistical issues about monitoring and the derivation and application of the limits. Many were 

concerned about the lack of approved methods or guidance for impingement survival monitoring. 

Several suggested that an impingement mortality numeric performance standard should not apply 

to facilities implementing technology considered to be BTA. Others noted that the proposed 

numeric performance standard was based on a small data set not broadly representative of waters 

of the U.S. Another commenter stated that EPA’s provision to require long-term monitoring to 

capture variation in the source waterbody is unnecessary, as an adequate sampling regime, in 

combination with an appropriately calculated IM numeric performance standard, will provide 

enough data to validate the long-term effects. 

The Agency has built a tremendous amount of flexibility into today’s rule, including a wide 

range of choices for achieving compliance with the rule’s BTA standards for impingement 

mortality. This flexibility allows facilities to select a site-specific (or unit-specific) approach to 

achieving compliance with applicable requirements and, as necessary, to coordinate compliance 

efforts with other regulatory constraints. While compliance with a numeric annual impingement 

mortality performance standard is one compliance alternative, the rule provides that other 

technologies and operational measures, including conformance with through-screen design 

velocity and through-screen actual velocity, may be used to achieve compliance with 

impingement mortality standards. The facility may choose the compliance alternative or 

alternatives that best alleviate any concerns about conducting performance studies, installation 

and/or operational costs, or monitoring. As such, today’s rule promotes research and 

development of available technologies and site-specific optimization of the technologies and 

methods used to reduce impingement mortality. In addition, EPA has simplified and reduced the 

monitoring requirements for impingement mortality compliance alternatives other than 

compliance with the numeric impingement mortality performance standard. See Essay 16. 

As outlined in the preamble to today’s rule, EPA has simplified the numeric impingement 

mortality performance standard from a monthly to a 12-month numeric impingement mortality 

performance standard. The derivation of the 12-month numeric impingement mortality 

performance standard is further discussed in Essay 16A. EPA has specified certain parameters 

for evaluating compliance with this standard, including aquatic species to be considered, 

sampling equipment characteristics, and minimum and maximum holding times for evaluating 

mortality. Today’s rule also includes a provision for rates of impingement that might be so 

exceptionally low at an intake as to be insignificant. In such circumstances, depending on 

documented information available, the Director has the discretion to conclude that the 

documented rate of impingement at the cooling water intake is so low that no additional controls 

are warranted. EPA also disagrees that long-term effects will be readily apparent. In site visits, 

EPA found that the species and counts at a site could change as rapidly as within a few years, 

Essay 22 264 
                                                            

and it was only by virtue of frequent monitoring that the facility could identify the return of 

species to the waterbody. The biological characterization at 40 CFR 122.21(r)(4) would be 

conducted every permit term, which could be supplemented with additional monitoring 

established by the Director under 40 CFR 125.96(c), to illuminate changes in the source 

waterbody. 

Barrier Nets

EPA also received many comments stating that barrier nets were both unnecessary and might be 

unavailable in many locations. EPA’s consideration of barrier nets can be found in Essay 18. 

Annual impingement mortality performance standard monitoring methods are addressed later in 

this essay. 

Entrapment

The proposed rule included a prohibition on trapping organisms in an intake structure with no 

viable escape route. Many commenters expressed concern that the proposed requirements were 

not well-defined and would require costly technologies not considered in EPA’s cost estimates. 

Moreover, in the commenters’ view, the requirements could be difficult to comply with, 

particularly where cooling systems employ impoundments or basins downstream of the initial 

intake structure. The final rule deleted the requirement that facilities demonstrate that their 

cooling water intake structures do not lead to entrapment. However, EPA does not agree that 

entrapped organisms should be ignored or go uncounted. A facility that entraps fish must count 

the entrapped organisms as impingement mortality, and would include such counts as part of 

40 CFR 122.21(r)(6). Then under either 40 CFR 125.94(c)(5) (or (c)(6)), if applicable, the 

Director will determine the modified traveling screens (or system of technologies) is BTA for 

that site. The Director makes this determination upon review of the optimization studies required 

under 40 CFR 122.21(r)(6), and thus the entrapment will have been considered. The Director 

may determine the number and type of entrapped organisms warrant additional technology. As a 

means of complying with the IM BTA standard, this could include technologies to reduce or 

eliminate entrapment as part of the traveling screens or the system of technologies. Alternately, 

the Director can require additional measures under 40 CFR 125.94(c)(8) or (9).47 Also, see 

Essay 18. 

Entrainment Mortality Reduction Requirements

In this section, commenters discussed EPA’s request for comment on different aspects of the 

proposed entrainment mortality requirements. Commenters discussed site-specific 

determinations for entrainment survival, reviewed criteria to guide evaluation of closed-cycle or 

identified other criteria to be used as BTA for entrainment mortality, reducing flow to be 

commensurate with the operation of a CCRS, and land constraints in implementing entrainment 

mortality BTA. 

47 See the TDD for further information regarding EPA’s cost analysis including barrier nets at certain facilities that 

already have traveling screens or a low intake velocity. 

Essay 22 265 
100 Percent Mortality of Entrainment Organisms

Some commenters supported allowing facilities to make site-specific demonstrations that 

entrainment mortality of one or more species of concern is less than 100 percent, but others 

supported the assumption of 100 percent mortality. Entrainable organisms generally consist of 

eggs and early life stage larvae. Early larvae generally do not have well-developed skeletal 

structures, have not yet developed scales, and in many cases are incapable of swimming for 

several days after hatching. The record shows that entrainable organisms that are collected 

frequently show poor survival in the case of eggs, and essentially no survival of larvae. 

Consequently, on the basis of the record information EPA has reviewed, for purposes of this rule 

EPA maintained the assumption that all entrained organisms die, i.e., no entrained organisms 

survive. Also see Essay 18. Commenters provided data showing that certain species have 

entrainment survival rates, and therefore EPA has retained a provision in today’s rule that allows, 

for monitoring purposes, a facility to demonstrate to the Director that the entrainment mortality 

for each species is less than 100 percent. Otherwise, if the facility chooses not to demonstrate 

actual survival, entrainment mortality after passing the cooling water intake structure is counted 

as 100 percent mortality. EPA disagrees that a facility should be able to use entrainment survival 

data from another site; given that entrainment impacts are highly site-specific (a point argued by 

industry), it is not reasonable to assume that a small number of entrainment survival studies 

could be broadly applied to facilities nationwide. Not only would the species be different 

between sites, but so could the physical, chemical, and thermal stresses that an entrained 

organisms is subjected to while passing through each facility. EPA also notes that this 

demonstration is not required; if a facility deems it to be too expensive or infeasible to complete 

in a reasonable time, it does not have to conduct the study. As noted above, EPA also disagrees 

that Directors will be unable to review these or any other permit application materials due to a 

lack of expertise. See preamble for further discussion of the peer-review requirements of the 

final rule. 

Land Availability

Commenters thought that it was inappropriate to have a standardized threshold for land 

availability with regards to determining BTA at that site. Refer to Essay 19 for a detailed 

discussion and response. 

Description of Entrainment Survival Study

Commenters also requested a description of studies demonstrating entrainment survival. The 

Phase II Regional Analysis Document (DCN 6-0003; EPA-HQ-OW-2002-0049-1490) discusses 

extensively in Chapter A7 the criteria used to evaluate entrainment survival studies that were 

analyzed as part of that rulemaking effort. Part of the intent of EPA’s review was to determine 

the soundness of the findings behind the entrainment survival studies. EPA reviewed the studies 

to determine if they were conducted in a manner that provided adequate representation of the 

probability of entrainment survival at the facility. The criteria EPA used to evaluate the studies 

focused on three main themes: the sampling effort of the study, the operating conditions of the 

facility during the study, and the survival estimates determined as the result of the study. Chapter 

A7 provides a list of questions EPA used to determine whether the entrainment survival studies 

provided adequate indication of the soundness of the science behind the facility’s estimate of 

potential entrainment survival. Studies submitted to demonstrate entrainment survival should 

Essay 22 266 
address those questions to adequately document the design and implementation of a sampling 

program intended to accurately establish the magnitude of entrainment survival. 

Further discussion of the review criteria selected to guide evaluation of closed-cycle or identify 

other criteria as to be used as BTA for entrainment mortality is in Essay 16. 

Further discussion of flow constraints commensurate with closed-cycle cooling is in Essay 17A. 

Application Requirements

Commenters provided many suggestions and critiques of each portion of the permit application 

process. Many comments were related to concerns about an excessive permit application burden 

on affected entities, the strictness of the proposed submittal timeline, and excessive resources 

needed to prepare and review materials. Several commenters stated that new studies should not 

be required if State environmental agencies find that entrainment issues have been sufficiently 

addressed at existing facilities. Similarly, some commenters suggested that facilities already 

utilizing closed-cycle recirculating systems should not have to submit all permit application 

materials. 

In response to comments on the proposed rule, EPA has simplified the permit application and 

supporting information requirements. The concerns commenters mentioned in this section were 

addressed earlier in this essay in response to permit applications and compliance deadlines. EPA 

also notes that each permit application requirement is intended to fulfill a specific purpose, while 

providing the Director with sufficient information to develop BTA requirements for both 

impingement mortality and entrainment; as a result, EPA disagrees that some studies should be 

eliminated. EPA recognizes that facilities may have already submitted materials to their Director 

that are equivalent in content to the permit application requirements; if this is the case, the 

Director may waive the requirement for certain studies. Many commenters were concerned about 

the definition and application of the concepts of “species of concern” and “fragile species.” 

These concerns are addressed later in this essay. 

Exemptions for Peaking Units

Several commenters were concerned that the extensive biological studies required to support 

permit applications under the proposed rule are unreasonably burdensome for peaking units. To 

the extent the peaking plant operates infrequently and the CWIS is not used, there is no need for 

sampling or monitoring during these zero flow days. In other cases, peaking plants continue to 

withdraw cooling water even while not producing power, and these operations result in 

impingement and entrainment. In other circumstances peaking plants operate at full capacity for 

a few months, most often during the summertime during local peaking energy demand. Where 

this period of operation corresponds to spawning periods, those facilities could also have 

significant impacts on impingement and entrainment. Additionally, there is no guarantee that a 

peaking unit will remain a peaking unit; it may operate more frequently and without notice to the 

Director. Therefore, it is both reasonable and necessary to obtain full permit application 

requirements from these facilities. Also see Essays 14 and 19. With regards to subsequent permit 

applications, see previous discussion of the streamlined application requirements earlier in this 

essay. 

Essay 22 267 
Peer Review

Many commenters suggested modification or elimination of the peer review requirements, citing 

undue burden on facilities and likely reviewer resource constraints. EPA notes some of these 

commenters insist that EPA peer review the critical data and analysis it conducts; EPA not only 

obtains peer review, EPA also obtains public review and comment. Those commenters not 

urging elimination of the peer review requirement requested that EPA provide implementation 

criteria and/or guidance on the peer review process. Commenters also noted that that the limited 

pool of qualified peer reviewers could result in delays in the permit application process. One 

commenter was concerned that industry would control peer review process, inhibiting the 

Directors’ ability to meaningfully review permit application materials. One commenter 

expressed partiality concerns in using peer reviewers and suggested that the technical adequacy 

of permit applications should be judged solely by oversight authorities. 

With regards to peer review, EPA disagrees with commenters that it is overly burdensome or 

inappropriate for inclusion in the permit application process. In Section VII.H.3 of the preamble, 

EPA recounts the typical use of the peer review process in Agency activities and confirms its 

value. EPA disagrees that industry will control the peer review process. Properly implemented, 

peer review is designed to allow a neutral third party to conduct an objective evaluation. 

Objective evaluation by independent subject-matter experts at that stage of the permit 

development process allows EPA staff to augment their capabilities, adds a degree of credibility 

that cannot be achieved in any other way, and can, in some cases conserve resources by steering 

the permit development along the most efficient course. While peer review can help expedite and 

support the permit development process, the Director (e.g., State or EPA staff) remains the 

ultimate arbitrator of the adequacy of the permit application materials, including any peer 

reviews that were conducted. EPA notes that peer review requirements are not expected to add 

undue burden to the permitting process in light of the reduced and simplified permitting 

procedures promulgated in today’s rule. EPA also notes the expanded and consolidated submittal 

timelines and points to peer review guidance materials available on the EPA web site. 

Several commenters requested that peer review requirements be waived for existing studies or 

updates to existing studies. Today’s final rule does not specify any exemptions from peer review 

requirements. EPA notes, however, that the Director has the discretion to waive some or all a 

facility’s 40 CFR 122.21(r) permit application requirements, based on previously submitted 

information. Therefore, the materials that the Director deems acceptable in lieu of submission of 

40 CFR 122.21(r) permit application requirements, including existing studies, may not have to 

go through the peer review process. 

Benefits Valuation Study

One commenter protested the requirement in the proposed rule for permit applications to provide 

an accounting in the Benefits Valuation Study of mitigation activities that have offset 

impingement and entrainment. The commenter suggested that there is no legal justification for 

consideration of habitat restoration during either national rulemaking under CWA 316(b) or 

during site-specific BTA determinations. EPA disagrees that the discussion of recent mitigation 

efforts already completed (up to the effective date of today’s rule) mitigation is unwarranted or 

irrelevant for making site-specific BTA determinations. The purpose for gathering this data is to 

determine how mitigation efforts that had been authorized as components of one of the 

Essay 22 268 
compliance alternative in the 2004 Phase II rule (up through the 2007 suspension of the rule) 

have affected fish abundance and ecosystem viability in the intake structure’s area of influence. 

This information is necessary for developing an appropriate social benefits valuation for use in 

making a site-specific BTA determination. Today’s final rule specifically removes the restoration 

provisions from the Phase I rule and restoration activities are not included in the compliance 

options available to existing facilities established today. Requesting information about mitigation 

activities that have taken place in the past does not constitute allowance of restoration measures 

for achieving the I&E standards set forth in today’s final rule. 

Default Values for Permit Applications

One commenter suggested that EPA define default values for certain expected costs to be used in 

permit applications, noting this it could streamline the permit development process. While EPA 

has conducted extensive evaluation and verification of these costs and parameters at the national 

level, the Agency disagrees that it should set or suggest standardized costs for cooling tower 

retrofit or other BTA approaches on a site-specific basis. Over the 10-plus years of this 

rulemaking, EPA has published the data used in its cost modules and other calculations and those 

values are available to the public for reference or other use. To set default or suggested expected 

values would infringe on the site-specific BTA approach EPA has selected. In today’s final rule, 

EPA requires facilities to present site-specific data such that a tailored approach may be used to 

determine the optimal EM BTA at that facility. 

Use of Existing Studies or Data

Several commenters asked whether they could submit historical data or other existing studies, or 

data that had already been collected to satisfy components of the 40 CFR 122.21(r) permit 

application requirements. Today’s rule specifies that facilities may use historical data that are 

representative of current operations of the facility and biological conditions at the site to meet the 

permit application requirements, so long as they provide documentation regarding the continued 

relevance of the data. The requirements for the impingement technology performance 

optimization and entrainment performance studies state that studies more than 10 years old must 

include an explanation of why the data is still relevant and representative of conditions at the 

facility. In addition, the explanation should clarify how the data should be interpreted using 

relevant terms (e.g., in terms of the updated definitions of impingement and entrapment). In 

general, historical data and existing studies more than 10 years old should include this 

accompanying information. EPA notes that, if the facility has previously submitted historical 

data or other existing studies that are substantially similar to the 40 CFR 122.21(r) permit 

application requirements, the Director has the discretion to waive the requirements for those 

portions of the permit application requirements. 

Similarly, commenters asked whether they would be able to submit previously gathered data on 

already-installed technologies to receive compliance credit or to demonstrate compliance with 

the IM standard or a compliance alternative. Today’s rule provides a compliance alternative at 40 

CFR 125.94(c)(6) for a facility to operate a system of technologies that will achieve the 

impingement mortality standard. This is the only compliance alternative that relies in part on a 

credit for reductions in the rate of impingement achieved by the facility’s system. The rule 

requires that the facility submit an estimate of those reductions to be used as credit towards 

Essay 22 269 
reducing impingement mortality, as well as any relevant supporting documentation, including 

previously conducted performance studies not already submitted to the Director as part of the 

facility’s entrainment performance studies. As such, the rule explicitly specifies that previously 

gathered data on system performance must be submitted to the Director under this compliance 

alternative. 

Chosen Method of Compliance with Impingement Mortality Standard

Several commenters requested that the rule allow facilities to meet the IM BTA standard by 

complying with one compliance alternative for part of the year and another alternative for the 

rest of the year (e.g., meeting the low velocity compliance alternative for part of the year and 

meeting the IM numeric IM performance standard for the remainder of the year). One 

commenter noted that their facilities implement variable operational standards to meet 316(b) 

permit requirements throughout the year. EPA considered operational measures such as seasonal 

operation or seasonal flow reductions which the Agency concluded were not appropriate as 

elements of the national BTA IM or E standards. Nonetheless, EPA intends for facilities to have 

the flexibility to employ such measures in a system of technologies to meet IM BTA on a sitespecific level as specified at 40 CFR 125.94(c)(6). Compliance with this alternative is based on a 

combination of a) reduction in rate of impingement; b) reduction in impingement mortality; and 

c) reduction in flow. Facilities choosing to comply with this alternative must demonstrate how 

the performance of the selected impingement reduction measures represents the best technology 

available for the site. Facilities may choose to implement different operational measures and/or 

technologies throughout the year based on site-specific conditions, so long as the complete 

system is then approved by the Director as BTA at that site. Facilities choosing to demonstrate 

reduction in impingement mortality must include two years of biological monitoring 

demonstrating the level of impingement mortality the system is capable of achieving. 

Entrainment Characterization Study

One commenter suggested that the biological baseline in the Entrainment Characterizations 

Study (ECS) should account for ecosystem damage already done by the facility, noting that 

organism counts and density will be much lower after years of damage. EPA disagrees with this 

approach, because it is impossible to completely characterize the magnitude of the facility’s 

effect on the waterbody without sufficient historical data, and that data is generally unavailable. 

The biological entrainment characterization component of the ECS requires a detailed 

characterization of the organisms in the vicinity of the CWIS, including data of sufficient 

duration to express variations in the ecosystem related to climate and weather differences, 

spawning, feeding, and water column migration. While this characterization may include 

historical data, that data is not required and entrainment BTA decisions will be made by the 

Director on the basis or conditions that are representative of the current operation of the facility 

and of biological conditions at the site. 

Several commenters suggested that they be allowed to submit a truncated analysis if a technical 

factor precludes the use of closed-cycle cooling (e.g., lack of land availability would preclude 

closed-cycle cooling), fine-mesh screens, or any other entrainment reduction technologies 

identified by the applicant or requested by the Director. EPA disagrees that facilities should be 

allowed to truncate their analyses in the case of a potentially infeasible candidate entrainment 

Essay 22 270 
reduction technology. In the commenter’s example of limited land availability, EPA found in site 

visits that this factor did not always prevent a facility from developing engineering solutions to 

accommodate the limit in space. Further, EPA expects some facilities with limited space may 

still be able to install closed-cycle for some, but not all, of the power generating or production 

units. Therefore, in the Comprehensive Technical Feasibility and Cost Evaluation Study (40 CFR 

122.21(r)(10)), today’s rule requires the facility to submit an engineering study of the technical 

feasibility and incremental costs of candidate entrainment control technologies, including closedcycle cooling, fine-mesh screens with a mesh size of 2mm or smaller, reuse of water or alternate 

sources of cooling water, and any other entrainment reduction technologies identified by the 

applicant or requested by the Director. Today’s rule specifically states that this study must 

include a description of all technologies and operational measures considered and documentation 

of factors that make a candidate technology impractical or infeasible for further evaluation. The 

preamble provides an example how land availability or unavailability may be discussed to 

demonstrate technical feasibility or infeasibility. 

Monitoring Requirements

In general, commenters thought that the proposed monitoring requirements were overly 

burdensome and costly, in some cases exceeding the calculated value of the benefit to the 

environment. Commenters requested the flexibility to have monitoring requirements reflect sitespecific considerations and reduced monitoring for consistent compliance or demonstration of 

proper operation and maintenance of a “pre-approved” BTA technology. Commenters also 

requested removal of monitoring requirements for the “life of facility.” Some commenters 

provided specific comments on EPA’s assumptions for sampling costs, including the staff time 

required, equipment costs, the effects of debris, moribund organisms, and monitoring/sampling 

frequencies (including diel and tidal cycles). Other commenters stated that the proposed rule 

contained too few compliance alternatives, and many facilities would not be able to meet the 

impingement mortality performance standard. These commenters were also concerned that a 

failure to meet the performance standard would constitute a violation of the facility’s NPDES 

permit and could result in significant fines or other penalties. In contrast, Riverkeeper stated that 

EPA should set minimum monitoring requirements to ensure adequate protection for organisms 

and to alleviate burden on the States. 

EPA addressed concerns regarding monitoring in the final rule by revising and simplifying 

monitoring requirements. Most significantly, biological compliance monitoring is no longer 

required for pre-approved and other approvable technologies in 40 CFR 125.94 (c)(1) through 

(5) of today’s rule beyond that required for the permit application, and monitoring may be 

greatly reduced for facilities choosing other compliance alternatives. EPA recognizes that 

biological monitoring can be expensive, which factored into EPA reducing those requirements. 

Furthermore, EPA has harmonized the monitoring requirements and timing between the 

impingement and entrainment mortality standards to reduce overall monitoring burden. At the 

same time, periodic biological data collection is necessary to update the biological activity in the 

vicinity of the CWIS. The final rule balances the costs of biological monitoring with the need for 

this information. Also see Essay 16. 

Additionally, EPA has expanded the compliance options available to regulated entities; many of 

the options added have streamlined requirements for monitoring and compliance. As a result, 

Essay 22 271 
facilities that anticipate that they may have difficulty meeting the impingement mortality 

performance standard can instead choose a different compliance alternative. Each compliance 

alternative contains demonstration requirements and only the option of demonstration of 

compliance with numeric impingement mortality performance standard (40 CFR 125.94 (c)(7)) 

contains monitoring requirements similar to those in the proposal. 

EPA agrees that monitoring requirements for the life of the facility can be unduly burdensome. 

Accordingly, today’s rule includes a compliance alternative (40 CFR 125.94(c)(5)) that allows 

facilities that demonstrate compliance with the impingement mortality numeric performance 

standard to request that the Director reduce monitoring requirements after the first full permit 

term in which these monitoring requirements are implemented, on the condition that the results 

of the monitoring to date demonstrate that the owner or operator of the facility has consistently 

operated the intake as designed and is meeting the requirements of 40 CFR 125.94(c). Similarly, 

for entrainment monitoring requirements, facilities must follow the monitoring frequencies 

identified by the Director for at least two years after the initial permit issuance. After that time, 

the Director may approve a request for less frequent monitoring in the remaining years of the 

permit term and when a subsequent permit is issued. 

Exhibit VIII-4 in the preamble to today’s final rule summarizes the minimum monitoring 

requirements for each compliance approach. Even implementation of a closed-cycle recirculating 

system, the most protective technology, requires daily monitoring of cooling water withdrawals, 

makeup water, and blow down flows to allow the Director to determine that makeup and 

blowdown flows have been minimized. EPA recognizes that monitoring comes with a certain 

cost and has carefully crafted appropriate minimum monitoring requirement for each technology 

considered. EPA has set minimum biological monitoring requirements for compliance with the 

numeric impingement mortality performance standard 40 CFR 125.94(c)(7). In establishing the 

biological monitoring requirements, EPA expects any approved monitoring protocols will 

consider the entire daily and (where appropriate) tidal cycles over which data collection should 

occur. Typically, facilities have collected impingement samples continuously for 6 or 8 hours 

and repeated this cycle to cover an entire 24-hour period. Stratifying collection in this manner 

allows an analysis of the diel variation exhibited by many aquatic organisms, which may be 

important. For example, in some species, larval life stages are more active at night and 

impingement rates may be higher; as a result, sampling during only daytime hours would not be 

reflective of the biological conditions at the facility. EPA also expects the approved monitoring 

protocols will ensure that sampling occurs during periods of representative intake flow and not 

during periods of non-peak flow or scheduled outages. 

EPA has also revised its cost estimates for impingement sampling in the ICR, as discussed in 

Essay 23. EPA has assumed 48 hours of staff time per sampling event for 2 staff (i.e., round the 

clock staffing), plus additional time for pre-event preparation and travel to the site. EPA also 

included costs for durable sampling equipment (e.g., a shed). These estimates are reasonable 

approximations for an average facility for national cost purposes. EPA further found the 

sampling costs reflect the range of costs for sampling actually conducted by facilities; naturally, 

the exact costs at an individual facility may be higher or lower. 

Essay 22 272 
Clarifying “Direct Measure”

Commenters requested clarification of the term, “direct measure” with regards to monitoring. 

The term “direct measure” has been removed from the rule language in reference to monitoring 

to evaluate compliance with impingement mortality performance standard. EPA agrees that 

direct measurement of intake velocity on a traveling screen may be problematic in some 

circumstances, and the final rule allows intakes to comply with the low velocity compliance 

alternatives by either calculation or direct measurement. Compliance will be demonstrated 

through monitoring and reporting of actual or calculated intake velocities. EPA expects that 

facilities will employ appropriate design and operational measures to ensure that 0.5 fps is not 

exceeded during minimum ambient source water surface elevations, as can be anticipated 

through best professional judgment using hydrological data. 

Annual Average

Commenters expressed concern that EPA expects facilities to track their compliance with the 

annual average standard on an ongoing basis, and to proactively modify their technology or 

operations when any individual monthly average suggests that they may be in danger of 

exceeding the annual average IM performance standard in the future. They note that this 

language suggesting that compliance with these standards can be “adjusted” does not recognize 

the delay in receipt of data from the laboratory and also ignores the seasonal variability of many 

species and the inherent variability in hardiness of species. One commenter expressed concern 

that there is the question of whether the annual average is or is not a “rolling average.” The 

proposed rule at 40 CFR 125.97(a)(2) required permittees to “update and submit your calculated 

annual average for each month covered by the report.” The final rule addresses these concerns by 

(1) making it clear that it promulgated a 12 month performance standard, and by providing six 

IM compliance alternatives that do not require biological monitoring to demonstrate compliance 

with the IM performance standard. Also see Essay 16A. 

Species of Concern and Fragile Species

Commenters were concerned that EPA assurances of Director discretion does not resolve how 

the rule would treat sensitive species that would be deemed “species of concern,” and thus be 

included in the impingement mortality counts. They suggested that EPA should also allow permit 

authorities to specify what “species of concern” will be used to measure compliance and that the 

difficulty of achieving the impingement mitigation standards would be mitigated by careful 

definition of species of concern to exclude particularly sensitive organisms with lower ecological 

value consistent with EPA’s statements in the preamble and the TDD. 

Commenters stated that EPA offers no evidence that the survival rates of the fourteen 

predominant species on which the impingement mortality performance standard is based are, in 

fact, representative of all species. They suggested that there should be no reliance by EPA on 

speculation that State permitting authorities will be inclined to exclude “highly prevalent” forage 

fish species or any other species for that matter, from being considered “species of concern” and 

that EPA should include all fish or specify excluded fish. One commenter stated that based on 

discussions with EPA staff, that they understood that the species of concern, and thus the fish 

whose mortality is to be measured, are to be finfish, not shellfish. They suggested that the rule 

Essay 22 273 
should make this clear and that EPA offers no explanation for excluding shellfish from these 

standards. They should apply, in aggregate, to all “species of concern.” 

Commenters were concerned that the Proposed Rule did not clearly define “species of concern” 

nor did it differentiate between “species of concern” and representative important species 

(“RIS”). They suggested EPA should adopt standards for hardy, intermediate, and fragile species 

and grant discretion to State Directors to identify species of concern. To adequately protect each 

species of fish, EPA should apply the impingement mortality standard to each species impacted 

by the cooling water intake system. EPA could develop IM standards based on categories of 

species, e.g., one for hardy species and one for fragile species. One commenter thought that EPA 

should not allow State permitting agencies to exclude any species from monitoring, sampling, or 

study requirements, including reptiles and marine mammals. 

First, the final rule provides six compliance alternatives that would not require a facility to 

conduct biological compliance monitoring for the IM performance standard. For those that elect 

to comply with the numerical IM performance standard, EPA addressed these concerns by 

eliminating from the final rule the species designations “species of concern” and “representative 

important species” and instead identifying fragile and non-fragile species. As detailed further 

below, this approach mimics the actual data forming the basis of the IM performance standard. 

EPA then developed the numeric impingement mortality standard for the final rule using data 

from only the identified non-fragile species. Facilities monitoring to demonstrate compliance 

with the numeric impingement mortality performance standard must measure mortality, 

including latent mortality, for each non-fragile, non-threatened, and non-endangered species 

collected during sampling events. Accordingly EPA disagrees that monitoring requirements 

should be limited only to selected species of concern. EPA notes the Director may require 

additional monitoring and may require additional controls for fragile-fish at 40 CFR 

125.94(c)(9)(i). EPA agrees that shellfish should be considered under the impingement mortality 

performance standard; see Essay 16A. While not traditionally viewed as “impingeable,” EPA 

also notes that many non-fish or shellfish species (such as sea turtles and marine mammals) have 

additional protections under other laws, such as the Endangered Species Act or Marine Mammal 

Protection Act. The Director may establish additional controls for these aquatic organisms at 40 

CFR 125.94(c)(9)(ii). For further discussion see Chapter 11 of the TDD and the Section VIII of 

the preamble. 

EPA notes that, in contrast to the proposed rule, the permit application no longer requires 

submission of the proposed “species of concern.” EPA found that the term “species of concern” 

was similar to terms used in the context of T&E (threatened and endangered) species, and was 

concerned about further confusion over existing Services or State requirements for such species. 

Furthermore, despite EPA’s efforts to distinguish between species of concern and RIS 

(representative indicator species) in the NODA (77 FR 34325, June 11, 2012), EPA found that 

many commenters were still confused by the language. EPA is therefore adopting the term 

“fragile species” and exempting fragile species from being counted to determine compliance 

with the numeric impingement morality performance standard. The term “fragile species” is 

meant exactly as it is used with the impingement mortality data and criteria used in calculating 

the impingement mortality performance standard of the rule. EPA defines “fragile species” at 40 

CFR 125.92, as a species of fish or shellfish that has an impingement survival rate of less than 30 

percent even when the BTA technology of modified traveling screens are in operation. EPA has 

Essay 22 274 
long recognized these species as having low survival rates under the best of conditions and 

fragile species have been shown to suffer from high rates of mortality even in control studies (see 

DCN 10-6810). The EPA does not intend for such naturally occurring mortality to be counted 

against a facility’s performance in reducing impingement mortality. EPA therefore took an 

approach to ensure that a facility’s performance in reducing impingement mortality as 

demonstrated by biological monitoring would reflect only the effects of its improvements to the 

CWIS technology, and not be confounded by effects of monitoring that are not caused by 

impingement. EPA notes the change in terminology to “fragile species” eliminates the proposed 

rule burden on States to review and approve each facility’s site-specific species of concern, and 

eliminates confusion over any T&E or RIS that may be subject to more stringent requirements 

under other Federal, State, and Tribal law. EPA also notes that the use of “fragile species” 

instead of “species of concern” greatly increases the transparency of the Agency’s impingement 

mortality performance standard. 

One commenter expressed concern that the proposed 12 percent limit would allow 100 percent 

mortality of vulnerable species as long as they represented a small portion of fish impinged and 

suggested that, in order to adequately protect each species of fish, EPA should apply the 12 

percent impingement mortality standard to each species impacted by the cooling water intake 

system. EPA disagrees; the IM performance standard was developed based on aggregating 

impingement mortality data across numerous species and EPA has concluded that it would be 

inappropriate to then apply a standard based on aggregated specie data to each individual 

species. Such an approach would require the development of a performance standard for each 

species of fish and is not a viable one, given the lack of available date to do so. Also see Essay 

16A. 

EPA disagrees that the exclusion of fragile species from the numeric impingement performance 

standard weakens the implementation of the numeric standard in the final rule. Fragile species 

are accounted in the baseline biological monitoring and are only excluded for measurement of 

compliance against the numeric standard (which is appropriate as the technology basis for the 

standard, modified traveling screens with fish returns is largely not effective against fragile 

species). On a site-specific basis, BTA technologies and practices will afford some measure of 

protection for all fish and shellfish, including fragile species. Today’s BTA for impingement 

mortality allows the Director to establish site-specific controls under 40 CFR 125.94(c)(9) to 

address fragile species. The Director may require additional measures such as behavioral 

technologies to protect fragile species, or additional monitoring for species not subject to the 

BTA requirements for impingement mortality at 40 CFR 125.95(c). Such monitoring 

requirements will be determined by the Director on a site-specific basis. 

EPA agrees that exclusion of “invasive” species is problematic and removed the language from 

the proposed rule that excluded measurement of invasive species for determining compliance 

with the numeric standard. The final rule does specify, however, that “all life stages of fish and 

shellfish” does not include other specified nuisance species. Therefore, many non-indigenous 

invasive species (e.g., zebra mussels) that are nuisance species are excluded in determining 

compliance with the numeric standard. EPA’s use of the term “invasive species” in the proposed 

rule may have been confusing because some might consider non-native stocked fish as invasive 

species. It was not EPA’s intention to exclude those types of fish from being counted towards 

compliance with the numeric IM performance standard. 

Essay 22 275 
Effects of Debris

Commenters expressed concern that some facilities experience very high debris loads on their 

traveling screens. They stated that this has the potential to substantially increase impingement 

mortality noting that impinged organisms are likely to be subjected to impact and abrasion from 

the debris resulting in increased mortality. They argued that there is no evidence in the record for 

the proposed rule that the modified traveling screens identified as BTA are able to separate 

debris and organisms effectively enough to achieve the impingement mortality standards and that 

heavy debris loads greatly complicated sorting and enumeration of impinged organisms during 

studies. They requested that provisions should be included in the rule that accommodate these 

natural events. They also noted that some NPDES permits have conditions that prohibit the 

return of debris to the source waterbody and that returning organisms impinged at these facilities 

while maintaining compliance with the permit condition that prohibits discharge of debris would 

require complete separation of debris from organisms, which they state is infeasible. EPA agrees 

that high debris loading and debris return prohibitions can affect mortality rates of fish returned 

from a traveling screen and may occasionally present difficulties when monitoring for 

impingement mortality. EPA also agrees that debris return prohibitions in NPDES permits may 

conflict with requirements to return impinged fish. EPA notes, however, the problems described 

will only have an impact on ability to comply for those intakes where the numeric performance 

standard alternative is selected. The impingement mortality performance standard is one of seven 

compliance alternatives and EPA expects that the numeric performance standard will be the 

selected compliance alternative for only a small portion of intakes. The problems described 

would not affect compliance via the compliant technology alternatives (i.e., closed-cycle, 0.5 

ft/sec velocity, and existing offshore intake). Therefore, EPA would expect a facility that has 

debris concerns will elect to choose one of the other six IM compliance alternatives. To the 

extent that a facility elects to comply with the IM standard via the optimized traveling screen or 

system of technology compliance alternatives, the Director will have the discretion to consider 

the impacts of the problems described. For these reasons, EPA has concluded that specific 

provisions regarding debris are not needed. 

IM Monitoring Methods

Many commenters expressed concern that there is no single, standardized approach to measuring 

impingement survival, because the collection and holding systems must be designed for each 

individual facility. They argue that the tests are time-consuming and expensive to perform, 

unduly burdensome, difficult to replicate, and subject to high levels of experimental error. One 

stated that EPA has not adequately recognized the difficulty of maintaining fish for a period of 

time and that using this kind of problematic procedure to determine compliance is unreasonable. 

One argued that such monitoring is unwarranted once either of the prescribed BTA standards has 

been met. One noted that EPA admits that it cannot point to standard methods for the collection 

and analysis of the type of biological samples called for in the Proposed Rule, much less for the 

determination of latent mortality and distinguishing it from natural morbidity. In general, they 

conclude that it is not feasible to regulate impingement mortality by requiring achievement of an 

IM numeric performance standards applied to pollutant discharges and suggest that EPA should 

delete or modify monitoring requirements for facilities that can demonstrate that their technology 

design meets EPA requirements and they are complying with an approved operation and 

maintenance plan. Riverkeeper states that EPA should require the Director’s approval for all 

sampling plans. EPA recognizes that at present, there are no standard methods for conducting 

Essay 22 276 
                                                            

 

impingement and entrainment studies and that there can be variability in designing a sampling 

plan between sites. EPA disagrees, however, that it is not feasible to regulate impingement 

mortality using a numeric performance standard and notes that the general methodology has been 

well-established over the 25-plus year timeframe facilities have been conducting impingement 

survival studies. EPA also disagrees that an impingement sampling plan must be approved by the 

Director prior to sampling. See DCN 10-6706 for a discussion of some fundamental study 

elements and parameters that are universally essential for the completion of impingement and 

entrainment surveys and DCN 10-6708 for a discussion of elements that should be incorporated 

into any sampling plan. EPA however, understands that many facilities would prefer to comply 

via alternatives that require less ongoing biological monitoring that involves less associated 

uncertainty and lower costs. EPA has addressed this by establishing in the final rule numerous 

other compliance alternatives that do not require ongoing biological impingement mortality 

monitoring. These alternatives incorporate many of the suggested approaches including defined 

compliant technologies that only require certification of continued optimized operation and 

maintenance. In many cases, impingement data collection will be required only for an initial twoyear study period. 

IM Monitoring at Each Intake

Several commenters asked about consolidating or eliminating monitoring requirements. They 

asked if IM monitoring could be conducted on a unit basis, rather than at each intake; if IM 

monitoring at a single intake could be used as a surrogate for similar intakes; and if facilities 

could, for compliance with IM performance standard, combine or average the counts of organism 

IM across intakes. Today’s rule establishes IM standards that may be applied at either the intake 

level (such as intake velocity) or the facility level (such as volume of intake flow). The rule 

clarifies that facilities may adopt an intake-specific compliance strategy at each cooling water 

intake; accordingly, individual monitoring and compliance requirements are applied at each 

intake. Given that source water and operational conditions at individual intakes may vary, as 

further demonstrated by some data sets provided by commenters,48 the final rule does not allow 

the owner or operator to consolidate or eliminate monitoring to demonstrate compliance at each 

intake complying with the IM performance standard. 

EPA notes that today’s final rule has removed biological compliance monitoring requirements 

for the compliance paths based on “pre-approved” technologies. In addition, there are three 

“streamlined” compliance alternatives available at 40 CFR 125.94(c)) (3), (5) and (6) that, after a 

facility has made a demonstration of system optimization as to minimize impingement mortality, 

have no subsequent biological monitoring and reporting requirements as compared to a facility 

that complies using the numeric impingement mortality performance standard. Therefore, there 

are several compliance alternatives available for facilities wishing to reduce or eliminate ongoing 

biological monitoring requirements. Note that these facilities still have biological 

characterization data gathering requirements as part of any subsequent permit applications. 

One commenter questioned whether facilities could have relief from IM monitoring during 

downtime or extreme circumstances. As shown in Exhibit VIII-1 of the preamble, EPA has 

48 For example, where intakes are located parallel to the shoreline and on a river bend, the upriver intake generally 

shows much higher rates of impingement. 

Essay 22 277 
projected that the overwhelming majority of the facilities within the scope of today’s rule will 

select IM compliance alternatives that do not have biological monitoring requirements. For the 

very small number (less than 1 percent) of intakes that are projected to demonstrate compliance 

with the IM performance standard, biological monitoring is only required on a monthly basis and 

not required during downtime or when the facility is not otherwise operational. Waiver of 

monitoring requirements during extreme events is not necessary because monitoring can be 

scheduled around short-term or emergency conditions. Such conditions should not affect a 

facility’s ability to comply with the 12 month impingement mortality performance standard, and 

such conditions should not interfere with overall optimized performance of impingement 

minimization technology or a suite of technologies. EPA expects that once a sufficient body of 

performance data has been collected, the facility would request less frequent biological 

monitoring under 40 CFR 125.96(f). Further, once the technology has been demonstrated to the 

satisfaction of the Director, EPA expects the facility would utilize compliance alternative 40 

CFR 125.94(c)(6) in subsequent permit cycles. Therefore even new and innovative technologies 

have a venue for demonstration of performance equivalent to that required by the IM standard, 

and EPA does not expect any facility would need to conduct frequent biological monitoring in 

perpetuity to comply with the BTA for IM. 

Remote and Visual Inspection

Commenters were concerned about the implementation of the required remote and visual 

inspections. The final rule requires all facilities with new units to either conduct visual 

inspections or employ remote monitoring devices when the cooling water intake structure is in 

operation. The facility must conduct such inspections at least weekly to ensure that any 

technologies installed to comply with 40 CFR 125.94 are maintained and operated to ensure that 

they will continue to function as designed. Some commenters supported this particular provision. 

EPA agrees that periodic inspections are one way to ensure that a technology continues to 

perform as intended and has retained these inspections. EPA is aware that, for some facilities, 

this requirement could pose a feasibility challenge (for example due to ice cover in the winter 

season, inability of divers to see through more than a few inches of water, or certain intakes in 

deep water). The rule, therefore, authorizes the Director to establish alternative procedures. See 

40 CFR 125.96(e). 

Monitoring Feasibility

Some commenters were concerned about challenging physical or other logistical conditions that 

would render the methodology and frequency of monitoring specified in the proposed rule 

impossible or impracticable. Commenters gave the example of CWISs that are located under or 

adjacent to active wharves or marine terminals where collecting the samples specified in the 

proposed rule would require putting divers in active shipping lanes or shutting down commerce 

for the duration of the sampling. Other examples of the challenges associated with impingement 

sampling provided in comments included impingement events caused by storms, the effects of 

mortality caused by sample holding, physical challenges to access proper sampling locations or 

to house biologists or analytical equipment, how to account for “carry over” of organisms not 

removed by the spray wash system, and selecting an appropriate sampling location that balances 

scientific integrity and worker safety. Commenters noted that the proposed rule allowed for 

compliance monitoring to take place at a location other than at the intake itself “where 

Essay 22 278 
appropriate,” and “as approved by the Director” in situations involving (but not limited to) 

forebays, barrier nets, or fish handling and return systems. They were concerned, however, that 

EPA did not specify the circumstances that would qualify for an alternative monitoring location. 

EPA recognizes that some facilities may be faced with certain challenges in developing and 

implementing a sampling program for impingement mortality. First and foremost, more than 90 

percent of facilities are expected to choose a compliance alternative that does not require 

biological compliance monitoring to demonstrate compliance with the numerical IM 

performance standard. Second, as noted above, this type of sampling is not new and has been in 

use at many facilities for several decades; to wit, the studies used to develop the impingement 

mortality performance standard demonstrate the availability and common use of these sampling 

techniques. In fact there are hundreds of studies in the record, spanning a full range of 

waterbodies, intake types, and CWIS including successful monitoring by those “difficult” 

situations described by commenters. EPA further considered these feasibility concerns by 

incorporating flexibility in the compliance alternatives established in today’s final rule; not all 

compliance options require impingement mortality monitoring, only one alternative requires 

biological compliance monitoring which EPA projects would be used by at most 1 percent of 

facilities as described above. All compliance alternatives include reduced monitoring over that 

which was described in the proposed rule. For intakes without traveling screens or those that 

have inaccessible sampling locations, the rule provides IM compliance alternatives that do not 

involve routine monitoring of impingement rate or impingement mortality (e.g., velocity 

reduction and system of technologies). 

In addition, facilities with intake structures that do not use traveling screens or other technologies 

that return fish unharmed to the waterbody may choose to comply with IM requirements via the 

“system of technologies” alternative. Compliance with this alternative is based on a combination 

of A) reduction in rate of impingement; B) reduction in impingement mortality; and C) reduction 

in flow. Only component B (reduction in mortality) involves frequent (monthly) biological data 

collection for at least two years. Component B can be zero as long as the other two are sufficient 

to meet the BTA standard. If there is no fish return then component B will be zero by design and 

there will be no need to perform monthly impingement data collection. Component A (reduction 

in the rate of impingement) may involve some initial biological data collection (near-field versus 

far-field, inspection for impinged organisms, etc.), but will likely be short-term and acceptable 

requirements will be subject to the discretion of the Director who can take site-specific 

limitations into consideration. Component C (flow reduction) can easily be monitored without 

interfering with terminal operations. Only component B (reduction in mortality) would require 

frequent monitoring or inspection activities that might interfere with terminal operations beyond 

the initial assessment. EPA has concluded that ample flexibility has been provided in the final 

rule, allowing facilities to choose a compliance alternative that obviates monitoring feasibility 

concerns. 

Taxonomic Identification

One commenter expressed concern that very few facilities would have employees with the 

education and experience necessary to make taxonomic determinations that would be required to 

monitor compliance with more-complex IM performance standard with different requirements 

for different groups of fish. Specialists needed to monitor IM do not exist at most facilities that 

Essay 22 279 
will be subject to the rule, and especially not at the manufacturing facilities and smaller electric 

utilities formerly covered by the Phase III rule. EPA agrees that such skills may not be present 

within the existing workforce and included in the ICR costs estimates the costs for skilled 

contract employees necessary to conduct biological monitoring. EPA also notes that in most 

cases such monitoring will only need to be conducted for an initial two-year study period. Those 

facilities that choose to comply with the impingement standard via the intake velocity or flow 

reduction commensurate with CCRS standards will not be required to conduct any biological 

compliance monitoring at all. 

Converts

One commenter expressed concern that EPA offers no remedy for non-compliance resulting 

from converts. EPA disagrees. EPA has defined impingement at 40 CFR 125.92(n) and 

entrainment at 40 CFR 125.92(h). These definitions are mutually exclusive in that the definition 

includes a mesh size of 0.56 inches. This approach completely eliminates any miscounting of 

converts. This approach was also adopted in the final rule to avoid penalizing facilities that 

utilize fine mesh screens and thus inflating the count of I and IM, as discussed in the preamble. 

Moribund Organisms

One commenter stated that scientific information exists indicating that impingement “selects” 

fish and shellfish of impaired health condition and, therefore, violations of the standards are 

likely to be frequent. Another commenter suggested that specific language should be drafted to 

account for naturally occurring mortality-inducing situations, such as due to red tide, so that the 

facilities are not adversely penalized for the natural mortality. EPA agrees that some organisms 

may become impinged as a result of their health being impaired due to naturally occurring 

factors. The final rule specifically allows for fish and organisms that are moribund (i.e., close to 

death) to be taken into account; see 40 CFR 125.94(c)(7) reference to “latent mortality.” The 

impingement mortality performance standard specifically excludes fragile fish from the 

calculation of impingement mortality. EPA has concluded that specific language is not required 

since the Director has discretion to take into consideration site-specific characteristics and 

condition of local fish species when establishing monitoring and reporting protocols. Also for 

compliance options involving traveling screens and system of technologies, the Director has 

discretion in determining what level of impingement meet BTA requirements. 

Biofouling

One commenter expressed concern that annual or bi-annual biofouling control measures to 

combat invasive bi-valve species (e.g., zebra mussels - mortality of both bivalve and fish species 

can occur prior to screened intakes as determined by the design of the once through cooling 

system) and requested that monitoring should exclude periods during which facilities undertake 

biofouling control measures. EPA notes that continuous biological compliance monitoring is not 

required. Monitoring requirements for entrainment will be determined by the Director on a sitespecific basis. In both cases, the Director has wide discretion in determining whether monitoring 

periods should include episodes of employment biofouling control measures. EPA expects that 

the Director would take into consideration the frequency of such measures in any determination 

of protocols and frequency of monitoring requirements. 

Essay 22 280 
                                                            

Zero Catch

One commenter observed that zero catches provide a statistical analysis problem in determining 

monthly and annual averages and questioned whether zero catches would be counted as zero 

mortality or as no data. EPA has concluded that, since the standard is expressed as a percent of 

total, the proper handling of the circumstance where no impingement occurred would be to count 

this as “no data.” See Essay 16. Another commenter noted that EPA should adopt a provision for 

facilities with very low impingement rates. EPA disagrees that zero catches would result in 

compliance issues, because compliance alternatives 40 CFR 125.94(c)(1) through (c)(4) do not 

require counting of fish, and compliance under 40 CFR 125.94(c)(5) and (c)(6) are based on 

those permit conditions that result in optimized performance of the BTA technologies. These 

permit conditions reflect the optimization study required at 40 CFR 122.21(r)(6) and reviewed by 

the Director, and the study would already reflect low rates of I or IM, including zero catches. 

Further, EPA has a de minimis rate of impingement alternative49 at 40 CFR 125.94(c)(11); see 

preamble for more details. 

New Units

Some commenters stated that the monitoring requirements for new units were excessive. EPA 

disagrees. Without any monitoring data regarding the facility’s intake flow and other parameters, 

the Director may not be able to determine if the new unit’s closed-cycle system is operating in a 

manner that minimized makeup and blowdown. Further, in most cases, new units would meet the 

BTA requirements with CCRS under 40 CFR 125.95(e)(1). This alternative requires a 

demonstration of flow for the new unit commensurate with CCRS requires flow monitoring, a 

parameter that is highly automated and very inexpensive. This monitoring requirement imposes 

virtually no burden. Flow monitoring for facilities that choose 40 CFR 125.95(e)(2) must 

demonstrate entrainment reduction equivalent to 90 percent or greater of the reduction that could 

be achieved through compliance with 40 CFR 125.95(e)(1). The type of monitoring in these 

circumstances is variable, and may include biological data collection in some cases. However, 

EPA concludes the requirements are necessary, reasonable, and affordable, and the requirements 

are similar to those required of new facilities in Phase I. Further, as noted in the comments (and 

in the rule), the Director may eventually reduce these monitoring requirements after the cooling 

system has been confirmed to reduce flows to the necessary levels. Additionally, EPA expects 

that the monitoring required will be very simple and relatively inexpensive—monitoring of flows 

into and out of the system is easily accomplished, especially with modern instrumentation and 

design that would accompany a newly constructed unit. 

Counting Impinged Organisms with the “Hypothetical Net”

Commenters had varying concerns about the procedures for counting impinged organisms using 

the “hypothetical net,” such as concerns over interactions with debris and how biologists would 

utilize a hypothetical net on segregating organisms during a sampling event. Several commenters 

agreed that impingement mortality should only be calculated using the organisms that would not 

have passed through a 3/8-inch mesh screen, while others thought the hypothetical net 

calculation would add significant difficulty to monitoring for impingement and entrainment. 

49 EPA did not predict which facilities would obtain Director approval to comply with IM via 40 CFR 125.94(c)(11); 

EPA assumed costs for technologies for all facilities; see the TDD for more information. 

Essay 22 281 
EPA maintains that this concept is still appropriate, as a facility needs a method to distinguish 

“impingeable” organisms from “entrainable” organisms, particularly at facilities with fine mesh 

screens or other technologies that differ from the basic screens with a mesh size of 0.56 inch. By 

impinging smaller life stages (which typically have lower impingement survival rates than larger 

organisms), affecting the facility’s overall impingement mortality rate and its ability to meet the 

performance standard; the hypothetical net helps these facilities by eliminating smaller 

organisms from the group of organisms that will determine compliance with the performance 

standard. Though today’s rule no longer mentions the proposed procedures for counting 

impinged organisms using the “hypothetical net,” the impingement mortality restrictions in the 

final rule are based on the operation of a modified traveling screen with a fish return. To ensure 

that a facility’s monitoring plan is consistent with the technical basis for today’s requirements, 

for those facilities that elect to comply with the IM standard via biological compliance 

monitoring, EPA is requiring facilities to monitor impingement mortality using a sample that has 

been passed through a sieve or net with no more than 0.56 inches maximum opening, so that 

only organisms that do not pass through this mesh size are counted. In doing so, facilities would 

retain (and therefore count) only organisms that would have been impinged on a 3/8-inch mesh 

screen, which was the technological basis used for developing the impingement mortality 

performance standard. As such, facilities can similarly apply a “hypothetical net” in that they 

could elect to count only organisms that would not have passed through a net with mesh 

openings less than 0.56 inches. The example given in the preamble is that a facility using a finemesh screen of 0.5 mm or diverting the flow directly to a sampling bay will need to count only 

organisms that remain if the flow passed through a net, screen, or debris basket fitted with 3/8­

inch mesh spacing. 

One commenter suggested that EPA must define what organisms are impingeable (versus 

entrainable) and evaluate the feasibility and performance of technologies for reducing mortality 

to organisms of that size and type. The commenter stated that, for facilities that cannot comply 

via the low velocity compliance alternative, requiring direct monitoring of all life stages of fish 

that are collected or retained in a 3/8-inch sieve unacceptably increases hazards to these 

organisms. EPA notes that the use of a sieve with a maximum opening dimension of 0.56 inches 

(3/8-inch) during sample collection is intended to distinguish between impingeable and 

entrainable organisms for regulatory purposes and must be used only in conjunction with intake 

screens that use finer or coarser mesh screens. EPA has concluded that this method is much more 

preferable since it is based on the design and performance of the BTA impingement technology 

upon which the performance standard is based and is relatively simple to implement. An attempt 

to define impingement and entrainment using lists of species and sizes would be a very difficult 

and imprecise method both to develop and implement especially considering the available data 

limitations. 

Methods for Evaluating Latent Mortality Effects Resulting from Impingement

Commenters responded to EPA’s request for comment regarding methods for evaluating latent 

mortality effects resulting from impingement. They were primarily interested in EPA 

establishing procedures for evaluating latent mortality, or eliminating the requirement entirely. 

Some commenters noted that there are significant challenges in conducting latent mortality 

studies and offered suggestions for how to conduct these studies or to interpret the results. 

Essay 22 282 
Today’s rule establishes the holding time for evaluating latent mortality (under the performance 

standard) as a period of 18 to 96 hours; the Director will ultimately select an appropriate holding 

time based on site-specific considerations, such as the species present. The Director has the 

discretion to prescribe an alternative holding period. After evaluating the data, EPA concluded 

that a range of holding times of 18 hours to 96 hours was acceptable for inclusion in the 

development of a performance standard because commenters had provided documentation 

showing that the actual time period typically had little effect on IM rates; see Chapter 11 of the 

TDD, Essay 16A, and the preamble for more discussion. Selecting an appropriate holding time 

will be a balance of monitoring for latent mortality (which would necessitate longer holding 

times) against the challenges of holding organisms for an extended period of time that may 

introduce mortality unrelated to being impinged (e.g., predation in the holding tank, needing to 

feed the held organisms). In contrast to the proposal, EPA counted all fish that died at any time 

during the holding period, instead of excluding those that were dead at time zero. By considering 

a wider range of holding times and other requirements, EPA was also able to utilize a larger set 

of data for calculating the performance standard, with broader geographic representation. (For 

more information, see DCN 12-6703.) The rationale for these revisions to the data acceptance 

criteria are described in further detail in the TDD, Chapter 11. EPA’s evaluation of holding times 

is further discussed in Essay 16A. 

EPA disagrees that monitoring requirements should not include evaluation of latent mortality. 

Facilities monitoring to demonstrate compliance with the numeric impingement mortality 

performance standard must measure mortality, including latent mortality, for each non-fragile, 

non-threatened, and non-endangered species. As discussed above, the rule explicitly references 

“latent mortality” to provide clarity. One commenter expressed concern that without a control 

test of similar species that was not exposed to impingement, it is not possible to determine 

whether any latent mortality was the result of impingement, entrainment into the sampling 

equipment, confinement within the handling/collection system, exposure to other organisms 

within the collection system or organism handling related to monitoring. Generally, up to 10 

percent mortality in a control test is considered acceptable in a whole effluent toxicity WET test 

and 10 percent mortality related to test conditions alone is too similar to the proposed annual 

average impingement mortality standard. EPA has revised the impingement mortality 

performance standard in the final to a value which is significantly greater than the 10 percent test 

related mortality suggested by the commenter. EPA’s standard does not include a control 

adjustment since the standard itself was developed with the effects of the sampling procedure 

built-in. EPA expects that facilities will design and conduct the tests in a manner that minimizes 

the effects cited and has concluded that facilities should be able to replicate the procedures used 

in the studies that comprise the standard development database. Also, EPA expects that many of 

the species most susceptible to increased mortality as a result of the sampling methodology are 

also fragile species which are excluded from the calculation of impingement mortality. Also see 

Essay 16A. 

Reporting Requirements and Record Keeping

In general, commenters were concerned about the burden associated with reporting requirements 

and the logistical difficulties in submitting reporting through monthly discharge monitoring 

reports (DMRs), such as the lag time for biological analysis of impingement sampling. 

Commenters also thought that the separate annual certification statement was not necessary, as 

Essay 22 283 
the information required in the certification could be addressed through monthly or quarterly 

reporting as required in the facility’s permit. Some commenters suggested that the annual 

certification statement and report only be required when significant modifications are made to 

the approved technology or the facility’s implementation practices. 

EPA disagrees that DMRs are an inappropriate submittal vehicle for all required reports. Today’s 

rule requires that the results of all monitoring, demonstrations, and other information to 

determine compliance with the permit conditions and requirements established under 40 CFR 

125.94 be included with the facility’s DMR or equivalent report. The required reports for 

monitoring activities are similar to requirements that are already in NPDES permits for effluent 

discharges. DMRs are a routine and existing mechanism for reporting monitoring data that is 

required by an NPDES permit. In addition, the Director has discretion in choosing the format of 

the DMR or the portion of the DMR used to submit required monitoring data. Similarly, the 

Director may allow some degree of lag time in submitting analyses that require lengthy analysis, 

as appropriate. EPA expects that, during the near term, EPA and State NPDES Authorities will 

be making a number of revisions to the NPDES program to address today’s requirements. These 

will include revisions to the DMR reporting form in some cases to provide for submission of any 

monitoring data required by today’s final rule. 

EPA has simplified the requirements for the annual certification and report requirement. 

Facilities that have not substantially modified approved technologies or implementation practices 

may submit a letter asserting that the information contained in the previous year’s annual 

certification is still pertinent. 

Facilities that have substantially modified operation of any unit that impacts cooling water 

withdrawals or operation of cooling water intake structures must provide a summary of those 

changes in the annual certification report and submit revisions to the information required at 

40 CFR 122.21(r) in its next permit application. 

Many of the peripheral concerns mentioned by commenters were addressed earlier in the essay in 

the response monitoring and reporting burden issues. 

Compliance with Other Laws

For a discussion of EPA’s consideration of relevant acts of Congress, Executive Orders, and 

Agency Initiatives in developing this final rule, see the final preamble. Also see Essay 59. 

Commenters were concerned that today’s rule not be applied in a manner that results in conflicts 

with other regulations, including the Information Quality Act (IQA). The commenter concerned 

about the rule’s conformation with the IQA particularly noted that EPA has not met the 

obligations of the IQA is disclosing all the statistical and scientific information used to calculate 

costs, quantify benefits, and to justify the Agency’s option selection. EPA disagrees that it has 

not met the transparency obligations set forth in the IQA. Throughout the 10-plus years and 

multiple proposals and NODAs associated with this rule, EPA has published a public docket 

including all the relevant materials not protected by confidential business information 

requirements used in the development of the rule. In addition, EPA published the Environmental 

and Economic Benefits Analysis for Proposed Section 316(b) Existing Facilities Rule, Economic 

and Benefits Analysis for Proposed Section 316(b) Existing Facilities Rule, and the Technical 

Essay 22 284 
Development Document with the 2011 proposed rule that described the statistical and scientific 

information used to calculate the costs and quantify the benefits of the rule. Stakeholders have 

had multiple opportunities to comment on these materials and request additional clarification 

about EPA’s procedures to calculating the costs and benefits that ultimately led to the regulatory 

options selected in today’s rule. In some cases, industry commenters requested EPA provide 

Excel spreadsheets with the models, data inputs, and outputs; EPA did so. EPA is not required to 

publish a formal analysis of its compliance with the IQA. However, EPA is confident that it has 

provided adequate access to all relevant materials and data used in the development of the final 

rule. Also see response to Essay 59. 

Another commenter was concerned about the rule’s impact on manatees, an endangered species. 

The commenter requested that EPA include a provision in the final rule stating that the 

regulations will not be construed or applied in a manner that results in adverse impacts to 

manatees or critical manatee habitat. The final rule has not made any specific mention of impacts 

to manatees but does consider threatened and endangered species, including 40 CFR 

125.94(c)(9)(ii) for other aquatic organisms. The final rule provides the Director the discretion to 

establish alternative entrainment requirements for new units if the data specific to the facility 

indicate that compliance for each new unit would cause adverse impacts on threatened and 

endangered species. Similarly, for existing units, the Director may consider in the site-specific 

BTA determination quantified and qualitative social benefits and social costs of available 

entrainment controls, including ecological benefits and benefits to any threatened or endangered 

species. Finally, the rule provides seven alternatives through which facilities may comply with 

the today’s IM requirements. This flexibility allows facilities to select a site-specific approach to 

achieving compliance with applicable requirements while addressing individual constraints such 

as the presence of threatened and endangered species. See Section VIII.K of the preamble for 

how permits for existing facilities subject to requirements under the Endangered Species Act will 

be handled. The 316(b) rule and preamble establish a number of requirements and commitments 

to ensure coordination and information sharing between EPA and the Services concerning permit 

applications and permit requirements for facilities with cooling water intakes under the rule. The 

rule ensures that the Services will have an early review of permit applications, will have the 

opportunity to recommend measures to include in the permit to protect listed species and critical 

habitat, and will have an opportunity to review draft permits for the same purpose at the time 

they are public noticed. The rule also specifies the Director’s authority to include measures in the 

permit to protect listed species and critical habitat. The preamble reaffirms EPA’s commitment 

to coordinate with the Services on State-issued permits and so that they include measures 

necessary to ensure that the permit will not jeopardize the continued existence of a listed species 

or result in the destruction or adverse modification of designated critical habitat. Also see 

Essay 10. 

State 316(b) Programs

EPA notes that in a number of areas of the country (California, Delaware, New York, and New 

England), permitting authorities have already required or are considering requiring existing 

facilities to install or retrofit to closed-cycle cooling systems. Today’s final rule does not alter the 

basic State-Federal scheme established in the CWA under which EPA authorizes States to 

implement the NPDES permitting program, including, according to their own rules and 

regulations, implementation of more stringent requirements. Existing facilities are in these states 

Essay 22 285 
are still subject to the Federal rule but some State requirements were considered in costing. In 

addition, the today’s final rule addresses the permit application requirements and ongoing permit 

proceedings for these facilities at 40 CFR 122.21(r)(1) and 40 CFR 125.98(g). 

Director’s Role

Overall, many commenters urged EPA to allow the Director wide discretion in making sitespecific BTA determinations (including expanding the list of factors that the Director may 

consider in setting entrainment requirements and allowing the Director to tailor entrainment 

requirements to minimize the burden of compliance), requiring permit application materials, and 

setting monitoring and reporting requirements. Several commenters requested that EPA delete 

the provision asserting that the permitting authority can include more stringent state-law-based 

requirements in permit conditions implementing the regulation. Commenters also requested 

exemption from impingement and entrainment mortality BTA analysis requirements for all 

facilities where final BTA determinations have been reached since EPA suspended the prior 

Phase II rule. 

EPA agrees that the Director needs wide discretion in making many determinations relevant to 

each facility. In today’s final rule, EPA requires the Director to make site-specific BTA 

determinations for entrainment. In addition, the Director has the discretion to waive or delay 

some permit application materials, and implement reduced monitoring and reporting 

requirements. These concerns are further addressed earlier in this essay. More specifically to 

CCRS, EPA agrees that fogging, icing, salt drift, and visibility or aesthetic impacts may also be 

considered in making a BTA determination, although these factors are likely to be less important 

because such impacts are easily overcome by modern cooling tower design. 

Setting More Stringent Standards

EPA disagrees that it should prevent States from mandating more stringent performance 

standards than those set by today’s rule, and it also disagrees that allowing States to set more 

stringent requirements will cause excessive energy costs. With the promulgation of the final rule, 

EPA has set national standards for the reduction of entrainment and impingement mortality. EPA 

understands, however, that the original intent of the Clean Water Act includes broad authority for 

States to implement CWA requirements. Thus, EPA has left a great deal of discretion to the 

individual State permit administrators (Directors) in setting the appropriate requirements for their 

facilities, as long as the requirements are not less stringent than minimal Federal requirements 

established by today’s rule. While States are obligated to ensure that the facilities in their 

jurisdiction comply with minimum Federal requirements, they are also authorized to set more 

stringent standards if they desire. EPA has determined that allowing States to set more stringent 

requirements will not increase energy costs or decrease energy reliability. 

Permit Proceedings Begun Prior to the Effective Date of the Final Rule

EPA recognizes that some States have invested considerable effort in developing and 

implementing section 316(b) permits and facilities have invested significant resources in meeting 

those requirements. While today’s final rule does not grant automatic exemption from 

impingement and entrainment mortality BTA analysis requirements for all facilities where final 

BTA determinations have been reached since EPA suspended the prior Phase II rule, the 

Essay 22 286 
regulation at 40 CFR 125.98(b) and (g) allows the Director flexibility where there are ongoing 

permit proceedings or where a BTA determination has already been made based on substantially 

the same information required at 40 CFR 122.21(r). In the case of permit proceedings begun 

prior to the effective date of the final rule, the Director may determine whether the information 

already submitted is sufficient. As such, the Director has the discretion to confirm or proceed 

with a determination of BTA standards for impingement mortality and entrainment without the 

information required in 40 CFR 122.21(r). The bases for the Director determination of sufficient 

information and BTA are specified at 40 CFR 125.98(g). 

Establishing a Policy to Disallow EPA Comments

One commenter requested that EPA establish a policy to accept the State permitting authority’s 

BTA determination based on BPJ without allowing EPA regional staff to object to draft permits. 

EPA disagrees such a policy could be established and reminds the commenter that NPDES 

permits, including 316(b) permit conditions, are subject to EPA oversight and also to the public 

notice and comments requirements at 40 CFR 124.10 and 40 CFR 124.11. The regulations 

mandate a public comment period during which any interested person may submit written 

comments on the draft permit or the permit application during the required public comment 

period provided. These comments could include objections to a State permitting authority’s BTA 

determination. In addition, the regulations at 40 CFR 124.13 specifically require that all who 

have concerns that any condition of a draft permit is inappropriate must raise all reasonably 

ascertainable issues and submit all reasonably available arguments supporting their position by 

the close of the public comment period. As such, EPA will not establish a policy that would 

circumvent the legal requirements required of the NPDES program including public notice and 

comment procedures. 

Requiring Additional Information

One commenter requested that the final rule be revised to specify that the permitting agency will 

use the data submitted in the permit application to address the factors at the proposed 40 CFR 

125.98(e)(1)-(9) and the facility will not be required to perform any additional studies. EPA 

disagrees that the Director should be limited to the information submitted with the permit 

application. In the final rule, EPA specifies at 40 CFR 125.98(i) that Director is authorized to 

inspect the facility and to request additional information needed for determining permit 

conditions and requirements. As such, the Director is explicitly granted the discretion to request 

additional information or require the facility to conduct additional independent studies deemed 

necessary to aid the Director in the BTA determination. 

Communications and Outreach

Several commenters requested specific and general guidance regarding procedures for 

implementing the requirements established in the final rule. Commenters urged EPA to maintain 

open communications with stakeholders throughout the rulemaking and option selection process 

and to work closely with States regarding regulatory requirements after publication of the final 

rule. EPA agrees on the importance of open communications and notes that the Agency has 

actively engaged the stakeholders in significant consultation and outreach activities during the 

development of the final rule. Stakeholders have actively participated throughout the several 

Essay 22 287 
phases over a decade of rulemaking. In particular, given that the final rule addresses facilities 

that had been previously regulated by the Phase II and Phase III rules, stakeholders have been 

provided with ample opportunity to participate in the process. EPA has staged symposia, held 

conference calls, conducted facility site visits, and performed other activities where EPA sought 

the input from various stakeholders. In addition, there have been many opportunities for 

stakeholders to comment throughout the different phases of 316(b) regulatory development. EPA 

considered all comments and concerns raised throughout the rulemaking process and addressed 

them, where relevant, in today’s final rule. EPA will evaluate the need for implementation 

support and guidance after publication of the final rule as the final rule will be implemented 

through the existing NPDES programs. EPA notes that the final rule does provide some guidance 

to Directors; for example, the preamble states that the Director may determine that no additional 

entrainment controls may be required if all analyzed options have social costs that are not 

justified by the social benefits (see discussion below). EPA staff also will be available to assist 

State permitting authorities in the review and approval of permit applications. 

Dry/Hybrid Cooling Towers

Several commenters requested that the rule preclude dry and/or hybrid cooling towers as BTA 

for impingement and entrainment mortality controls. EPA disagrees that dry or hybrid cooling 

towers should be precluded as BTA options. Today’s rule states that a closed-cycle recirculating 

system may include a facility with wet or dry cooling towers. In addition, flow reduction has 

been defined as any modification to a cooling water intake structure or its operation that serves to 

reduce the volume of cooling water withdrawn, including variable speed pumps, seasonal flow 

reductions, wet cooling towers, dry cooling towers, hybrid cooling towers, unit closures, or 

substitution for withdrawals by reuse of effluent from a nearby facility. As today’s rule allows 

operation of a CCRS or various flow reduction measures to comply with the impingement 

mortality BTA standard, EPA has chosen not to preclude dry or hybrid cooling towers as BTA 

technologies. In some locations, availability of water may result in the need to consider hybrid or 

dry cooling. Manufacturing facilities already incorporate dry cooling in many unit processes; this 

indicates that dry cooling is available and demonstrated in at least some situations. Further, EPA 

intends for manufacturers to obtain credit for flow reductions already obtained; see preamble for 

more discussion. Note, however, that EPA recognizes that dry cooling is significantly more 

expensive that wet cooling. The use of dry cooling towers is further discussed in Essay 17A. 

Social Cost‐Benefit Analysis in Establishing Entrainment Standards

Commenters on this topic requested clarification of the social cost-benefit test. Several 

commenters also requested that EPA clarify that the State Director must apply cost-benefit in 

establishing entrainment standards and must reject an available technology if its costs are not 

justified by the benefits. Some commenters also stated that site-specific cost and benefit 

estimates be used in determining BTA, as opposed to national scale or model costs. The role of 

cost and benefits (including a specific cost-benefit test) is discussed in Essay 15. 

The rule states that the Director, in establishing a facility’s site-specific BTA entrainment 

reduction requirement, must consider the factors spelled out in 40 CFR 125.98(f). Today’s final 

rule does not specify the weight the Director must afford each factor when determining 

entrainment requirements. These factors include a requirement that the Director must consider 

the quantified and qualitative social benefits and costs of available entrainment technologies. The 

Essay 22 288 
Director must determine whether the entrainment technologies considered have social costs that 

are justified by the social benefits, or whether the technologies would cause unacceptable 

adverse impacts that cannot be mitigated. In such cases in which the information on benefits is 

adequate to make this determination, the Director has the discretion to reject an otherwise 

available technology as BTA standards for entrainment if the social costs are not justified by the 

social benefits and determine that no additional control requirements are necessary beyond what 

the facility is already doing. Generally, EPA agrees that site-specific estimates of costs and 

benefits are preferable for determining BTA; however, estimates that are calculated using a 

model cost approach (for example) should not be discarded, as they still likely provide some 

value, particularly if site-specific data is absent or incomplete. See Essay 15 for additional 

discussion on the role of costs and benefits in determining BTA. 

Today’s rule also allows the Director to establish alternative entrainment requirements for new 

units if the data specific to the facility indicate that compliance for each new unit would result in 

compliance costs wholly out of proportion to the costs EPA considered in establishing the 

requirements at issue or would result in significant adverse impacts on local air quality, 

significant adverse impacts on local water resources other than impingement or entrainment, 

adverse impacts on threatened and endangered species, or significant adverse impacts on local 

energy markets. This provision is identical to such a provision in the Phase I rule for new 

facilities. See the preamble for further discussion. 

Essay 22 289 
Essay 23: EPA’s Information Collection Request (ICR) and Administrative

Costs of the Rule

In addition to technology costs and O&M costs incurred as a result of complying with the rule, 

facilities will also incur administrative costs to comply. Examples of these costs are the cost of 

obtaining a 316(b) NPDES permit (including the costs of preparing an NPDES permit 

application), ongoing monitoring costs, and the costs of materials purchased to support a 

facility’s demonstration of compliance. These costs can be expressed in terms of labor hours to 

complete a given task or in dollars required to purchase the necessary materials (also known as 

“other direct costs” [ODCs]). 

The Paperwork Reduction Act requires that every Federal agency obtain approval from the 

Office of Management and Budget (OMB) before collecting the same or similar information 

from 10 or more members of the public. If EPA decides to gather such information, the EPA 

must prepare and submit for approval to OMB an Information Collection Request (ICR). The 

ICR describes the information to be collected, gives the reason the information is needed and 

estimates the time and cost for the public to answer the request. After reviewing the ICR and 

comments received from the public, OMB may approve or disapprove the ICR. An agency may 

not conduct or sponsor, and a person is not required to respond to, a collection of information 

unless it displays a currently valid OMB control number. The OMB control numbers for EPA’s 

regulations in 40 CFR are listed in 40 CFR Part 9. 

In the proposed Existing Facilities Rule, EPA described the proposed information collection 

requirements (e.g., new submissions that would be required as part of the permit application) and 

included costs associated with information collection requirements in the costs of the proposed 

rule. EPA also reported estimated burden associated with the information collection requirements 

for the total industry, for individual facilities, and for the Directors. See 76 FR 22262-22263. For 

the proposed rule, EPA based its information collection cost estimates on its previously approved 

ICR for the Phase II rule. 

Today’s final rule streamlines some aspects of the permit application and implementation 

process and would impose reduced information collection requirements in comparison to the 

Phase II rule. For example, six of the seven IM compliance alternatives eliminate the need for 

costly biological compliance monitoring as compared to the Phase II rule. However, EPA 

recognizes that some facilities subject to today’s final rule were not subject to the Phase II rule. 

EPA received comments on its information collection estimates in the proposed existing facilities 

rule. Where appropriate, EPA revised the information collection requirements in the final rule to 

incorporate these comments. EPA has also developed a new ICR rule to accompany this final 

rule that more accurately reflects the requirements and applicability of this final Existing Facility 

Rule. EPA notes that its total burden estimate associated with the information collection 

requirements in today’s final rule is much less than that estimated at the time of the proposal. 

Further, this new ICR also provides more meaningful information because, as explained above, it 

reflects both the applicability and requirements of today’s final rule after consideration of public 

comments on the proposal (and subsequent Notices). EPA is publishing in the Federal Register 

Essay 23 290 
this new ICR to provide the public an additional opportunity to comment on the associated 

burden. Following receipt and consideration of the comments, EPA will again publish it in the 

Federal Register and submit the ICR to OMB for approval. While the public has already been 

provided the opportunity to comment on the information collection requirements and burden 

throughout this rulemaking process, this approach provides yet another opportunity to comment 

on EPA’s estimates before OMB makes its final determination. As such, EPA is not in violation 

of the Paperwork Reduction Act. The Paperwork Reduction Act requires EPA to make the ICR 

available for public review and comment, but it has no requirement to do so at the same time that 

a proposed action is made available for comment. EPA also notes that no facilities will be 

required to submit any information for this Final Existing Facilities Rule until this new ICR has 

been approved. 

Essay 23 291 
Essay 24: Technical Development Document

Introduction

EPA received a number of comments that suggested corrections to or disagreed with information 

in the Technical Development Document (TDD). Responses to those comments are below. 

Basis for Developing Costs

Several commenters stated that EPA was inconsistent with how it described the development of 

estimated costs in the rule, preamble, and TDD. EPA disagrees. The preamble summarizes the 

cost methodology, whereas the TDD provides the detailed methodologies, algorithms, cost 

equations, and the basis for each component. Some commenters appear to confuse the 

technology basis for the impingement mortality performance standard and the technology costed 

for compliance with that standard. The rule requires facilities to meet an IM performance 

standard based on modified traveling screens with a fish-friendly fish return system. The rule 

does not require facilities to install a modified traveling screen; that technology was chosen as 

the basis for developing the numeric impingement mortality performance standards; see Section 

IX.B in the final preamble, which states that “this does not preclude the use of other 

technologies.” Each facility may choose the technology that they will use or install to meet the 

impingement mortality requirement, as well as choosing one of seven compliance alternatives for 

demonstrating it has met the requirement. EPA’s costing approach reflects that reality. For 

purposes of estimating national level costs of compliance with the rule, EPA developed a cost 

model that assigns one or more technologies to a model facility and estimated the costs for that 

facility. These model facility costs were then summed such that all likely in-scope facilities were 

included in the national costs estimate. See TDD Chapter 8 for a detailed description of how 

EPA applied this methodology to develop facility-level costs for the final rule. Also see Essay 

21. EPA agrees with commenters that each facility may require different modifications to its 

technology to meet the impingement mortality standard and, as noted above, the rule allows for 

various ways to demonstrate compliance. See Section IV of the preamble for additional 

discussion of the seven compliance alternatives for the IM standard. 

In the final rule, EPA notes that none of the BTA standards for IM at 40 CFR 125.94 require 

modified traveling screens. One of the compliance alternatives at 40 CFR 125.94(c)(5) allows a 

facility to select optimized operation of modified traveling screens as a way to meet the IM 

standard. The final rule at 40 CFR 125.92(s) defines modified traveling screens to mean a 

traveling screen that incorporates measures protective of fish and shellfish. The definition at 40 

CFR 125.92 lists a number of protective features that can be found on a modified traveling 

screen. In explaining what EPA meant in the proposal when discussing modified traveling 

screens, EPA cited a Fletcher (1990) article to illustrate that several features of Ristroph screens 

can be modified or optimized in ways that significantly reduces impingement mortality. This 

does not mean that modified Ristroph screens are the only type of screens that form the basis of 

the IM performance standard, nor does it mean modified Ristroph screens are required. For 

facilities choosing this compliance alternative, the permit application at 40 CFR 122.21(r)(6) 

requires a complete description of the modified traveling screens and associated equipment 

including, for example, type of mesh, mesh slot size, pressure sprays and fish return 

Essay 24 292 
                                                            

mechanisms. Finally, the definition at 40 CFR 125.92(s) states “examples of modified traveling 

screens include, but are not limited to: modified Ristroph screens with a fish handling and return 

system, dual flow screens with smooth mesh, and rotary screens with fish returns or vacuum 

returns.” 

Several comments expressed concern that a modified Ristroph traveling screen was required by 

the rule. As explained above, this is not correct. And contrary to some comments, EPA’s cost 

methodology appropriately reflects that facilities may employ various approaches; EPA did not 

assign costs for all facilities to comply with the IM performance standard by installing modified 

traveling screens. The summary of technical survey data in the TDD shows that 73 percent of 

manufacturers and 93 percent of all power generators (or 83 percent of the total in-scope 

universe of facilities) have traveling screens prior to this rule. But the costs developed for the 

final rule do not presume all facilities will replace or upgrade their existing screens with 

modified Ristroph screens or similarly performing screens in order to comply with the rule.50 

EPA has made this clear in the preamble at Exhibit VIII-1 and the TDD, providing EPA’s 

projections of how facilities will choose to comply with the IM requirements. EPA projects that 

29 percent of intakes will use modified traveling screens to comply with the BTA requirements 

for IM. Other facilities will use intake velocity, closed-cycle cooling, offshore velocity caps, or a 

system of technologies to meet the BTA requirements for IM. 

Commenters note that the TDD describes the methodology for assigning technology modules, 

including technologies that are not modified traveling screens, in estimating the costs of today’s 

rule (EPA notes that this is referred to by the agency as the cost basis). As discussed above, the 

rule does not require a facility to install a specific technology; it simply requires that the facility 

meet a certain level of performance. It is the facility’s choice as to what technology they will use. 

Site-specific factors will play a significant role in a facility’s choice of technology; it is unlikely 

that every facility will actually install modified traveling screens to comply and this is reflected 

in the flow charts describing how a compliance technology is assigned to estimate the costs. For 

example, a facility with an existing offshore intake would be highly unlikely to completely 

abandon their existing intake just to build a new shoreline intake with modified traveling screens. 

They would be more likely to install a less costly technology such as a velocity cap or 

wedgewire screen to reduce the intake velocity. As evidenced by the seven IM compliance 

alternatives in the final rule, EPA acknowledges that there are other demonstrated technologies 

that achieve performance equal to or greater than modified traveling screens. As described in 

Chapters 6 and 7 of the TDD and the preamble, a number of other technologies can also be 

highly effective and EPA assigned these technologies to a substantial number of model facilities. 

Additionally, the inclusion of other technologies in EPA’s cost estimates actually increased the 

overall compliance costs, as these other technologies are typically more expensive than installing 

a modified traveling screen. For example, an expanded intake for wedgewire screens with a 

design velocity of 0.5 fps is more expensive than modified screens with a fish return. However, 

facilities may have other reasons for selecting a particular compliance alternative, and minimum 

cost may not be the only reason a facility choose a particular compliance approach. As the 

50 The commenters noting that text in the preamble at 76 FR 22214/1 that EPA estimated costs by assigning Ristroph 

screens to all facilities could be interpreted to mean facilities were required to install such screens. As described 

elsewhere in the preamble, the TDD, and in the response to comments, this was not the case. A variety of 

technologies were used to develop compliance costs. 

Essay 24 293 
compliance alternatives based on these other technologies meet or exceed the IM BTA 

performance standards, EPA is providing the flexibility for a facility to choose that technology 

and its cost estimates reflect this flexibility. For more information regarding EPA’s cost 

estimates for screens, please refer to Essay 21. 

Similar to the above misunderstanding regarding traveling screens, some comments expected all 

facilities to reduce intake velocity to 0.5 fps. As explained at proposal at 76 FR 22202 and 

repeated in the final rule, EPA did not find that low intake velocity was widely available and 

achievable for all existing facilities. See preamble Section VI. Therefore, the final rule does not 

establish low intake velocity as the national BTA nor does it establish performance standards 

based on low intake velocity. EPA notes, however, that the final rule includes 0.5 fps as a 

compliance alternative for the IM performance standard because the impingement mortality 

performance achieved with reduced intake velocity performs better than the technology basis for 

the performance standard in the final rule. EPA notes that because reduced intake velocity is not 

widely available and therefore not a viable BTA basis for the final rule, EPA generally did not 

attempt to estimate costs for most facilities which employ traveling screens that might choose to 

reduce their intake velocity to comply with the rule. These facilities were generally assigned 

costs for upgraded traveling screens. The exception to this was in costing facilities with known 

intake velocities that were very close to 0.5 fps, EPA did assign the cost module for variable 

speed pumps which EPA estimated may be used by approximately 100 intakes to meet the 0.5 

fps velocity compliance alternative. See TDD Chapter 8. 

Some commenters indicated EPA did not properly account for costs of IM requirements at 

facilities that already have closed-cycle cooling. EPA disagrees. At proposal, EPA assigned costs 

for screen upgrades to facilities already employing closed-cycle cooling to be consistent with the 

overall approach for addressing impingement mortality described in the proposed rule. However, 

in the final rule, this would represent an overestimate of costs because the final rule provides a 

compliance alternative for a properly operated closed-cycle system to meet the impingement 

mortality standards. EPA expects no further technologies will be required to achieve the BTA 

standard for IM if a properly operated closed-cycle cooling system is used. Therefore, for the 

final rule analysis, EPA appropriately did not include costs related to traveling screens (or other 

IM technologies) for those facilities with CCRS already in-place (reflecting 18 percent of 

intakes, see Exhibit VIII-1 in the preamble) to comply with the IM standard. 

Lastly, one commenter discussed the usage of alternative technologies and how these could be 

used to demonstrate compliance with the IM performance standard. EPA agrees that alternative 

technologies may be effective in meeting the IM performance standards, and has included a 

system of technologies compliance approach at 40 CFR 125.94(c)(6) for this purposes. EPA 

provided examples of credit for existing technologies and alternative technologies in the NODA, 

and has included them again in the final preamble Section VIII. Also see Essay 16 and preamble 

Section VIII for discussion of how alternative technologies may be used to meet the final rule. 

Technology Performance

One commenter states that the TDD does not sufficiently describe the performance of 

entrainment technologies. The commenter specifically states that there is a lack of performance 

data for flow reduction technologies other than cooling towers. EPA disagrees. The TDD 

Essay 24 294 
                                                            

 

 

 

 

describes multiple types of entrainment technologies, including flow reduction and fine mesh 

screens.51 The final TDD’s Chapter 6 provides an overview of the suite of available E 

technologies and their performance. EPA notes that the principle of flow reduction is the same 

for any flow reduction technology; a gallon of water not withdrawn equates to 100 percent of the 

organisms in that gallon as no longer being entrained. Cooling towers generally offer the greatest 

reduction in flow and therefore the greatest reduction in entrainment.52 Variable speed pumps are 

not intended to match the flow reductions realized by a facility-wide cooling tower retrofit; they 

simply offer a measurable reduction in flow as part (or all) of a facility’s response to reducing 

entrainment. The amount of flow reduction is entirely dependent on the facility’s configuration 

and operational needs, thus the reduction will vary somewhat between facilities. As stated in the 

TDD, variable speed pumps (where feasible) result in a maximum flow reduction of 10-15 

percent, and more typically will result in a flow reduction of about 8 percent. The availability 

and effectiveness of seasonal flow reductions and scenarios for water reuse are very site-specific, 

and at a minimum are typically not available for baseload power generating facilities and many 

manufacturers, as these facilities need to operate all year (see Essay 15). These are flow 

reduction options that some facilities could undertake as all or part of a system of technologies 

compliance approach (as well as fulfill any regulatory or permit-related requirements).53 

Some commenters suggested intake location was not properly considered, particularly for 

entrainment. As explained in the final rule, intake location (in combination with other 

technologies) is an approach that, while not widely available and thus not BTA, may allow a 

facility to comply with today’s IM standard. For IM, the final rule includes a compliance 

alternative for a facility to take credit for an advantageous intake location by demonstrating that 

the intake is in a location that is less susceptible to impingement. EPA did not use a relocated 

intake as the technology basis for BTA for impingement mortality because it is not an available 

technology at most existing facilities, nor is a relocated intake alone demonstrated to meet the IM 

performance standard in all cases. For example, small rivers may have limited locations suitable 

51 Note that the commenter uses the term “entrainment mortality” when describing technology performance. 

Typically, entrainment mortality refers to the survival of entrainable organisms that pass through the entire cooling 

system of the facility, where they are subjected to thermal, mechanical, and other stresses. (See footnote 38 in 

Chapter 6 of the proposed TDD for more information.) EPA assumed that entrained organisms experienced 100 

percent mortality. Data provided in comments showed that in some circumstances, some eggs survive entrainment. 

However, in general the data does not support comments purporting significant entrainment survival, and EPA 

continues to assume for purposes of national rulemaking that entrainment results in 100 percent mortality. For this 

reason, EPA’s focus in the final rule is entrainment, not entrainment mortality.

52 EPA also discusses “combination” cooling systems in Chapter 6 of the final TDD. In these systems, only part of a 

facility uses a closed-cycle cooling system. For example, if one unit uses a cooling tower, it would achieve a 

reduction in flow of greater than 94 percent, but its other unit could be operating as a once-through system, which 

offers no reduction in flow. However, taken as a whole, the facility has realized a nearly 50 percent reduction in its 

flow relative to a full-flow baseline. 

53 In particular, seasonal reductions are highly dependent on season and the organisms present. Conceptually, if a 

facility is located in a waterbody where entrainable organisms are only present for a short time, it could schedule 

outages or periods of reduced flow to coincide with the entrainment season and operate the remainder of the year as 

a once-through facility with minimal risk with regard to entrainment. On the other hand, a facility located in an 

estuary with virtually year-round spawning of multiple species is unlikely to be able to utilize seasonal reductions. 

Manufacturers are unlikely to be able to shut down during peak entrainment periods every year. EPA further 

examined a case study of seasonal flow reductions for the Saugus River, and found that biological monitoring would 

be needed to identify the upcoming peak entrainment season, which is likely to shift each year based on weather, 

temperature, and other climatic factors. 

Essay 24 295 
for a relocated intake, and even larger waterbodies may have navigational issues that constrain 

the location of an intake structure. Furthermore, a relocated intake alone would be unlikely to 

achieve a level of performance comparable to the BTA performance standards for IM. For 

example, the offshore data for velocity caps in the record shows the density of organisms does 

not drop sufficiently to equate to the BTA performance standards for IM in all cases. EPA found 

the far offshore location (defined as greater than 800 feet off shore) must be combined with a 

velocity cap in order to perform better than the BTA performance standards for IM. Because of 

the far offshore distance, this alternative is, therefore, more likely to be available to facility 

intakes located on an ocean, an estuary, or the Great Lakes. For those not located on an ocean, 

estuary or Great Lake, EPA expects facilities will choose to comply with the IM performance 

standard via one of the other compliance alternatives. EPA found that relocation of an existing 

intake structure is costly (including civil work, permits, capital costs, and installation costs) and 

unlikely to be the most cost-effective choice for an existing facility. See TDD Chapter 6 for more 

information about the performance of intake location. Nevertheless, the final rule allows a 

facility to take credit for reductions in impingement resulting from the intake location. Nor does 

the final rule prejudge whether a facility may achieve some or all of its IM obligations through 

intake location. For example, EPA is aware that some intakes are located on the bend of the 

river, adjacent to a cold water source, or otherwise deliberately situated where fish are less likely 

to reside. The rule at 40 CFR 125.94(c)(6) provides a compliance alternative that allows a 

facility to demonstrate the performance of intake location for IM. 

The final rule does not mandate any technology to meet entrainment requirements. The rule 

establishes a framework and requires studies to inform the site-specific BTA determination to 

reduce entrainment at existing facilities. Since the rule requires BTA for entrainment to be 

determined on a site-specific basis, the rule already provides the flexibility to consider intake 

location as well as intake relocation. 

One commenter stated that several pieces of information on the California coast and the 

performance of velocity caps were incorrect. EPA appreciates these comments on the TDD and 

has addressed these items as described below: 

	 The discussion regarding kelp forests on page 6-46 was not intended to imply that 

facilities located near a kelp forest are more or less likely to cause an adverse 

environmental impact. As the introduction to the bullet in question states, the existence of 

kelp forests is a unique feature of the California coast and may be important in 

determining the effectiveness of a velocity cap. EPA appreciates the additional 

information on kelp forests and has made revisions to the final TDD as appropriate. 

	 EPA agrees that the statement on page 22202 of the proposed rule preamble about intake 

velocity being slightly lower due to a pressure differential when using a velocity cap is 

not entirely accurate. EPA agrees this is generally not the case, and has corrected the 

TDD accordingly. 

	 EPA appreciates the additional information on the sampling conducted at Huntington 

Beach, El Segundo, and Scattergood and has included these data in the revised TDD as 

appropriate. 

Essay 24 296 
EPA notes that this information is not related to the technology basis for the IM performance 

standard in the final rule nor to the site-specific BTA entrainment determination at the vast 

majority of intakes/facilities in the U.S. This information is specific to certain facilities located in 

California. To the extent that this information is relevant to the compliance alternative selected 

by facilities in this area or to their site-specific BTA entrainment requirements, this information 

can be submitted and considered by the Director. 

One commenter questions EPA’s exclusion of technology performance data derived in a 

laboratory setting, specifically with regard to cylindrical wedgewire screens. EPA notes that the 

commenter only mentions studies that relate to cylindrical wedgewire screens. In the specific 

case of wedgewire screens, EPA agrees laboratory data may be useful because fish diversion is 

difficult to measure, and impingement of fish on a wedgewire screen is difficult to sample in 

native settings. However, because this technology was not selected as the technology basis for 

the impingement mortality performance standards, the source of data for wedgewire screen 

studies (whether from a field study or a laboratory) were not used in developing the performance 

standards, and the remainder of the comment is irrelevant. For further discussion of criteria for 

data acceptance, see TDD Chapter 11 and Essay 16A. 

EPA has previously noted that wedgewire screens are typically designed with a maximum 

through-screen velocity of 0.5 fps. Wedgewire screens work because of a combination of factors 

including low velocity, sweeping velocity, flow dynamics, etc. Regardless, the final rule 

provides compliance alternatives at 40 CFR 125.94(c) for a maximum through-screen velocity of 

0.5 fps. EPA recognizes the performance of low intake velocity by providing the compliance 

alternative for either design or actual intake velocity. This compliance alternative is not limited 

to wedgewire screens. As indicated above, the final rule allows any intake (including a 

wedgewire screen) with a maximum through-screen velocity of 0.5 fps as meeting the 

impingement mortality standard. 

Site‐Specific Data for Capacity Utilization Rate

One commenter stated that the capacity utilization rate for one of its facilities was an error and 

reported as too low. In general, EPA notes that the utilization rates used in the analysis regarding 

the feasibility of a spawning season-oriented regulatory option for entrainment (flow reduction 

by virtue of seasonal operation, as discussed above) used information about capacity utilization 

provided in the industry questionnaires and representing the years 1998-2000. While the 

commenter provided more recent operational data, in the context of analyzing the technical 

feasibility of the seasonal operation as a regulatory option, the data used by EPA is sufficient to 

demonstrate that this option is not feasible on a national scale. EPA made this conclusion 

because the snapshot of the industry over this time period illustrated that many facilities would 

not be able to provide power as needed locally and still be consistent with strict controls of 

reduced operations during the spawning season. More specifically, EPA found that in most 

locations, reduced operations during spawning seasons and peak entrainment seasons frequently 

coincided with peak power demands in the summer. See TDD Chapters 5 and 6. As discussed 

above, most manufacturers operate all year, and seasonal reductions in operations every year 

would not be viable at such sites. Also see Essay 35 and the TDD, discussing how most 

manufacturers do not have annual maintenance outages on the shoulder months. Therefore 

reduced operations would result in lost revenues. Accordingly, EPA did not revise the analysis 

Essay 24 297 
with the most current facility-specific CUR data. On the other hand, EPA recognizes that 

utilization changes on an annual basis and has used the most recent available utilization rates for 

its economic analyses. See the EA for more information. 

EPA notes that the final rule provides authority to consider alternative requirements for certain 

facilities with low capacity utilization rating (CUR) at 40 CFR 125.94(c)(12). EPA found that 

low CUR facilities are generally peaking plants that operate at full capacity for a short duration 

during a few months or less. EPA further found that some sites continue to withdraw water 

through their cooling water intake structure even when no power is being generated. If that 

period of cooling water intake operation corresponds with times when spawning is occurring, 

those facilities could have significant impacts from impingement and entrainment. Therefore, 

EPA did not exempt all low CUR facilities from requirements, or develop a subcategory for such 

units. However, as discussed in the preamble, the Director may consider less stringent controls 

for intakes dedicated to low CUR power generating units. See 40 CFR 125.94(c)(12) and Essay 

19 for details. With respect to entrainment, energy reliability is one factor the Director may 

consider when establishing entrainment controls (see 40 CFR 125.98(f)(3)). Also see Essay 19. 

Analysis of Uncertainty

One commenter states that EPA inadequately addressed uncertainty in its development of 

estimated compliance costs. EPA disagrees. As the commenter notes, the TDD describes the 

multiple ways in which EPA’s estimated costs are conservative. The TDD for the final rule 

expands on this uncertainty analysis. Additionally, as described in Chapter 8 of the final TDD, 

EPA used a model facility approach for estimating the national compliance costs. Given that 

EPA does not have data for every potentially regulated facility, it is not possible for EPA to 

develop site-specific costs, probability assessments, and other analyses as suggested by the 

commenter. However, EPA’s cost analysis does take into account a wide variety of site-specific 

data in determining the most appropriate compliance technology, the size of said technology, and 

other site-specific factors that will affect the facility’s response to comply and, ultimately, its 

cost to comply. As such, EPA’s cost estimates have a significant degree of site-specificity to the 

model facilities; no two model facilities receive exactly the same technology and cost. 

Additionally, the commenter referenced uncertainty analyses conducted in the development of 

benefits. See the EBA for more discussion of uncertainty analysis specific to benefits. Also see 

Essay 22. 

Essay 24 298 
Essay 29: Cumulative Impact of Multiple EPA Regulations on the Electric

Power Sector

Overview of Comments

Several commenters expressed concern that EPA did not consider the cumulative burden of all 

recently-promulgated and currently pending regulations on the electric power industry in 

developing the section 316(b) Existing Facilities Rule and assessing its impact. Commenters’ 

concerns include the following: 

	 Compliance with multiple regulations during the same timeframe would be too costly and 

will result in higher electricity rates, reliability issues, and job losses due to premature 

retirement of generating units. 

	 Ohio Public Utilities Commission (PUC) urged EPA to assess the impact of these 

multiple regulations on individual States.
 

	 The relatively short period to comply with multiple regulations may not give facilities 

enough time to install all compliance technologies required under these regulations, in 

which case facilities will be prohibited from operating until compliance activities can be 

completed (Western Business Roundtable). The likelihood of adverse reliability effects is 

high in such instances. Western Business Roundtable cited a recent policy resolution by 

the National Association of Regulatory Utility Commissioners (NARUC) that it may take 

five years and more for facilities to complete all retrofit projects required under multiple 

regulations. 

	 To ensure that compliance with the section 316(b) Existing Facilities Rule along with 

other recently proposed and pending regulations does not result in adverse reliability 

effects, EPA must consult with the governmental and non-governmental agencies 

responsible for grid reliability and electric resource adequacy and do so in a way that this 

consultation is known to the public (National Mining Association). 

	 Taken together, multiple regulations affecting coal generating units will adversely affect 

not only the coal industry, but the entire U.S. economy. These rules will directly affect 

employment in the coal industry and indirectly affect employment in the overall economy 

as a result of higher energy prices and consequently, will impair U.S. competitiveness, 

GDP, and economic activity generally (National Mining Association). 

	 Anthracite Region Independent Power Producers Association (ARIPPA) urged EPA to 

consider the impact of the section 316(b) Existing Facilities Rule on ARIPPA electric 

power facilities that use coal refuse for electricity generation to make sure the rule does 

not force these facilities to retire prematurely. ARIPPA points out that, from an 

environmental perspective, the reclamation of coal refuse piles eliminates one of the most 

significant sources of water pollution in the historical coal mining regions of this country. 

Further, by utilizing coal refuse as a fuel source, ARIPPA facilities remove coal refuse 

piles and allow communities to reclaim land that would otherwise remain idle and 

unproductive for decades. 

Essay 29 299 
	 Electric power facilities may face difficulty meeting the compliance requirements of 

multiple regulations during a short timeframe due to shortages of available capital, 

materials, and labor. 

	 Some commenters urged EPA to account for potential losses associated with “stranding” 

air pollution control devices previously installed to comply with air regulations in 

instances when facilities shut down or repower before this installed equipment is fully 

depreciated. 

	 The need to comply with multiple regulations will affect companies’ decisions regarding 

whether to build new generating units. 

	 Multiple regulations with lengthy generating unit downtime for installing compliance 

technical will impact grid stability and transmission system reliability. 

Impact of the 316(b) Final Rule in the Context of Multiple Environmental Regulations

Affecting the Electric Power Industry

EPA has taken account of the potential cumulative impact that multiple environmental 

regulations may have on the electric power industry. The EPA’s economic impact analysis of 

both the Proposed and Final Section 316(b) Existing Facilities Rules (proposed and final rules) 

on the electric power industry specifically took account of recently promulgated air regulations. 

Based on their breadth of effect and potential cost, EPA views these air regulations as the most 

important other final regulations affecting the electric power industry, and therefore, EPA 

concluded these should be assessed in its evaluation of the cost and impact of the final 316(b) 

existing facilities rule. Other regulations (e.g., Coal Combustion Residuals and other Clean Air 

Act rules) are under consideration that may affect this industry, but as any requirements (and 

associated costs) are not yet determined, it is appropriate and reasonable to take into account 

only those recent requirements that are known and final. 

The results of this analysis are discussed in Chapter 6 of the Economic and Benefits Analysis for 

the Proposed Section 316(b) Existing Facilities Rule (EBA) report and Chapter 6 of the 

Economic Analysis for the Final Section 316(b) Existing Facilities Rule (EA) report, 

respectively. For this analysis, EPA used the Integrated Planning Model (IPM®), a 

comprehensive electricity market optimization model that assesses such impacts within the 

context of regional and national electricity markets. EPA has used IPM to analyze the impacts of 

various regulatory actions affecting the electric power sector over the last decade, including the 

Phase II and Phase III 316(b) regulations, Final Mercury and Air Toxics Standards (MATS), and 

Cross-State Air Pollution Rule (CSAPR). The IPM platform EPA used in the market model 

analysis for the final rule incorporates costs and market-level effects of final MATS and final 

CSAPR and then applies the 316(b) requirements on top of that. As described in Chapter 6 of the 

EA report, based on this analysis, EPA found that the final 316(b) rule will lead to a very modest 

increase in capacity retirements – less than 0.1 percent of total baseline capacity at the national 

level and the highest percent, 0.8 percent, of baseline retired capacity of any North American 

Electric Reliability Corporation (NERC) region, is projected to occur in TRE. EPA assesses that 

these very small retirements are inconsequential relative to total national and regional generating 

capacity. As a result, the final rule will not significantly affect electric supply reliability – either 

nationally or by NERC region. 

Essay 29 300 
                                                            

 

 

EPA notes that any comments received above other promulgated rules or rules under 

consideration such as comments about statements in the preamble to the MACT rule are outside 

the scope of this rulemaking. 

Impact of 316(b) Final Rule on Electricity Rates, Total Economy, and Employment

The EPA found the final rule will result in only small effects on electricity rates nationally, and 

at the level of individual NERC regions. For the final rule, under an assumption that all 

compliance costs would be passed through to consumers in electricity rate increases, the EPA 

estimated that rates would increase by approximately 0.009 cents per kWh across the United 

States. On a percentage basis, the estimated rate increases are comparably small, both nationally 

and by region: the estimated percentage increase in electricity rates averages 0.09 percent 

nationally, with the largest increase by region being only 0.15 percent. The EPA found that these 

increases to be very low, particularly when viewed in light of the environmental benefits the 

EPA expects will be achieved by this regulation. See Essay 39. 

In terms of broader economic effects, the EPA expects minimal impact from the final rule. Given 

the low cost of the rule in relation to the total economy (estimated total annual cost of $275 to 

$297 million,54 depending on discount rate, which is less than 0.01 percent of GDP in 2012), 

EPA concludes that the final rule will not adversely affect U.S. competitiveness, GDP, and 

economic activity, generally. Also see response to Essay 55. 

In the analysis for the final rule, the EPA did not specifically assess the employment effects from 

early retirement of generating units; however, because (1) only 23 units (out of 14,920 

generating units analyzed in IPM), accounting for 0.1 percent of total market capacity, are 

projected to retire early due to the final rule, (2) these retired units do not contribute significantly 

to electricity supply in the baseline case, with 15 and seven units having a capacity utilization 

rate of zero and less than 11 percent, respectively, and only one unit with substantial capacity 

utilization, approximately 66 percent, and (3) some jobs will be gained as the result of new 

generating units constructed to replace the retired units, EPA does not expect significant, if any, 

job losses from capacity effects associated with the final rule. See Essay 36 for more discussion 

of employment effects of the final rule. For more discussion on the impact of the final rule on the 

U.S. economy, see Essay 37. 

Need for Consultation and Coordination

Concerning commenters’ arguments that the EPA should consult and coordinate with agencies 

and organizations that are responsible for grid reliability and electric resource adequacy, the EPA 

notes that it developed the final rule with substantial interagency review, and opportunity for 

consultation and input from the Department of Energy, the Federal Energy Regulatory 

Commission, and other federal agencies. 

54 All costs and economic impacts reported in this document reflect the assumption that all facilities with cooling 

water system impoundments will qualify as baseline CCRS, and will not need to install additional technology to 

meet the impingement mortality performance standard under the final rule (for more information on this assumption, 

see Chapter 1 of the EA). 

Essay 29 301 
Impact on Coal Usage and the Coal Industry

In regard to NMA’s concerns about the rule’s potential impact on coal usage and the coal 

industry, as discussed in Chapter 12 of the EA report relative to the Executive Order 13211: 

Actions Concerning Regulations That Significantly Affect Energy Supply, Distribution, or Use, 

based on the IPM analysis, the EPA found that the final rule will not have a significant adverse 

effect on coal usage by the electric power industry. From the IPM analysis described above, the 

final rule causes only a 0.1 percent reduction in total coal usage. Again, while EPA did not assess 

the change in jobs in the coal industry as the result of the final rule, given the small change in 

coal usage by the electric power sector, the EPA does not expect significant job losses in the coal 

industry. 

Impact on Coal‐Refuse Based Generation

In regard to ARIPPA’s concern about the rule’s potential impact on facilities using coal refuse as 

fuel source to generate electricity, EPA concluded that the final rule would not significantly 

affect such facilities. As discussed in Chapter 12 of the EA report, the EPA’s IPM analysis 

showed that the final rule will not force generating units using coal refuse, captured in the “waste 

coal” category, to retire prematurely. 

Adverse Impact on Decisions to Build New Units

As discussed in Chapters 4 and 6 of the EA, EPA found that the new unit provision of the final 

rule will not deter existing facilities from constructing new, standalone units at existing facilities 

that would be subject to the new unit provision. EPA conducted this barrier-to-development 

analysis in two parts. EPA compared the compliance costs for new units to the overall cost of 

building and operating generating units, on a per MW basis, to assess whether the required 

addition of a closed-cycle recirculating system (CCRS) as part of a new unit, would substantially 

increase the cost for the new standalone unit. Additionally, EPA assessed these costs as part of 

its electricity market analyses using IPM; this analysis tests the impact of the new unit provision 

on electricity markets accounting for the expected number and timing of new unit installations, 

and provides additional insight on whether the costs of complying with the new unit provision of 

the final rule would affect future capacity additions. Neither analysis showed that the final rule 

would substantially increase costs or affect future capacity. 

Adverse Impact Due to Compressed and Overlapping Compliance Periods from

Multiple Regulations

The final rule provides substantial flexibility to Permit Directors in establishing the specific 

schedule and compliance requirements for individual permitees as they comply with the rule. 

Specifically, the final rule gives Permit Directors the authority to establish specific compliance 

requirements and compliance schedules, and does not include a requirement for compliance with 

the IM performance standards within a specific universal timeframe. EPA expects, however, that 

the existing unit provision of the final rule will generally result in compliance within a relatively 

lengthy period of eight years after promulgation. EPA did not specify universal compliance dates 

for IM standards because the specific method of compliance with these standards is tied to the 

determination of BTA entrainment control requirements. Under the existing unit provision of the 

final rule, facilities must meet IM requirements as soon as practicable after issuance of a final 

permit establishing the BTA entrainment control requirements, as determined by the Permit 

Essay 29 302 
Director. The final rule aligns compliance deadlines for IM and entrainment control 

requirements. If technologies required for compliance with IM and entrainment control standards 

overlap, which could result in facilities needing more time to comply with IM standards, the 

Permit Director will schedule compliance with the IM requirements to match the schedule for the 

entrainment control requirements. 

All facilities will be required to follow their schedule as determined by the Permit Director. The 

schedule of requirements established by the permitting authorities will ensure compliance with 

those requirements as soon as practicable. In developing technology-installation schedules for 

Electric Generators, EPA expects permitting authorities to take into account compliance 

requirements of other regulations and take measures to ensure adequate energy reliability and 

necessary grid reserve capacity during any expected facility outage associated with installation of 

compliance technology. In addition, as discussed in the EA, the resource requirements of the 

final rule – in terms of estimated capital outlay, near-term capacity effects, and ongoing 

operating costs and effects – are relatively small in themselves. As a result, facilities should not 

face unreasonable challenges in obtaining financial capital, materials, or labor for 316(b) rule 

compliance – even as they may also be meeting requirements from other environmental 

regulations at approximately the same time. 

Financial Losses from Capacity Retirements

The EPA understands the argument and concern raised by the commenters regarding the 

potential financial losses some companies may face if they retire generating units before the 

equipment they installed to comply with other regulations is fully depreciated. However, all 

regulations involve costs and potential impacts of the sort described. Moreover, as described 

above, the EPA foresees only a small impact in terms of early retirements of capacity as a 

result of the 316(b) final rule. 

Potential Impact on Grid Stability and Transmission System Reliability

Some commenters argued that the multiple environmental regulations, including the 316(b) 

existing facilities rule, will adversely impact grid stability and transmission system 

reliability. Commenters made this argument specifically in the context of the expected 

occurrence of lengthy downtime for generating capacity to install compliance technology, 

and difficulty in bringing sufficient electricity from other operating units to meet local 

electricity needs, when nearby capacity is out of service for technology installation. In terms 

of the impact of the 316(b) rule itself, in this context, the EPA first notes that downtime for 

installation of impingement mortality technology for the vast majority of units beyond 

ordinary scheduled maintenance outages, is zero. Second, the EPA conducted an analysis of 

reliability for this rulemaking and found the impacts would be incrementally very small. 

One commenter notes that the EPA cited information collected during site visits that several 

urban areas were identified where the existing transmission system would not be able to 

transfer sufficient electricity during periods of extended downtime or that, in some areas, 

even though excess capacity could be generated by other plants within the area, it may not 

be enough to replace the capacity lost during the extended downtime. The EPA notes that 

the commenter is referencing site visits to Los Angeles, CA and that the information was 

specific to the installation of closed-cycle cooling. After reviewing its site visit information, 

the EPA did not find that this information was more broadly applicable geographically. As 

Essay 29 303 
discussed in the preamble, the EPA did not find reliability to be dispositive in its 

consideration of closed-cycle cooling as the entrainment BTA. Third, the final rule provides 

flexibility in the compliance schedule. For those facilities that elect to comply with the IM 

performance requirements via a compliance alternative that may necessitate more lengthy 

downtime beyond the normally schedule maintenance outages, the Director has the 

flexibility to consider local reliability concerns in scheduling the compliance timeframes. 

EPA cannot predict the outcome of the site-specific entrainment determinations, but notes 

that Directors similarly have flexibility to consider local reliability in the determination of 

BTA for entrainment on a site-specific basis as well as the implementation schedule. In the 

EPA’s judgment, the short or nonexistent net downtime period for most units, combined 

with Permit Directors’ flexibility to set and adjust compliance schedules, will mitigate any 

potential concerns regarding grid stability and transmission system reliability. 

Essay 29 304 
Essay 31: Cost and Economic Impact Analysis: Methods and Approaches

Overview of Comments

Some commenters raised concerns with EPA’s approaches for analyzing the cost and economic 

impact of the 316(b) existing facilities rule. Particular concerns include the method for 

annualizing costs and benefits, and various aspects of the economic impact analysis. The 

comments include: 

	 American Chemistry Council (ACC) claimed that, according to the Technical 

Development Document for the Proposed Section 316(b) Existing Facilities Rule (TDD), 

EPA annualized social costs over 10 or 30 years, depending on the cost component, while 

in the Economic and Benefits Analysis for the Proposed Section 316(b) Existing 

Facilities Rule (EBA) report it says that EPA used the 50-year annualization period. ACC 

suggested EPA explain this discrepancy. 

	 Some commenters expressed concern over the 50-year period EPA used to annualize 

social costs for the analysis of the Proposed Section 316(b) Existing Facilities Rule 

(proposed rule). These commenters argued that this methodology underestimates true 

upfront investment requirement and suggested EPA use the 10-year annualization period 

in accordance with the approach suggested by the Congressional Budget Office (CBO). 

Using the 10-year annualization period will, in turn, lead to a higher cost-to- benefits 

ratio. 

	 Some commenters pointed out that EPA used a different annualization period in the cost 

and economic impact analyses conducted in support of the remanded Phase II Rule and 

the Phase III Rule; specifically, commenters claimed, EPA annualized costs over 10 or 30 

years, depending on the cost category. Some commenters pointed out that for the 

remanded Phase II Rule specifically, EPA annualized social costs using the 7-percent 

discount rate over 10 years. These commenters stated that EPA provided insufficient 

explanation for this methodology change and urged EPA to provide a better one. 

	 Midwest Generation, Edison Mission Energy, LLC (EME) expressed concern over the 

30-year period EPA used to model benefits, contending that if closed-cycle cooling were 

required many facilities would shut down leading to benefits actually occurring over a 

shorter time frame. 

Some commenters expressed concern with the methodology EPA used to assess the impacts of 

the proposed rule on regulated facilities. These comments include: 

	 Kansas City Board of Public Utilities (KCBPU) argued that in its cost-to-revenue 

analysis at the level of parent entity, EPA incorrectly use the sum of facility-level 

revenue owned by a given entity instead of this entity’s revenue. 

	 KCBPU also stated that EPA has underestimated the cost of compliance of the section 

316(b) regulation in general, but also the compliance cost per unit in sales to customers. 

Essay 31 305 
	 American Municipal Power, Inc. (AMP) expressed concern that EPA underestimated the 

full cost of the section 316(b) regulation because the Agency did not properly account for 

retirement of generating units. Specifically, AMP claimed, while EPA provided estimates 

of the number of regulated manufacturing facilities estimated to retire as the result of the 

CWIS rule (73 separate manufacturing facilities representing 13 percent of the total), the 

Agency failed to account for any retirements of the regulated electric power facilities. 

	 The United States Steel Corporation (USS) argued that cost-to-revenue analyses EPA 

used to assess the impact of the section 316(b) regulation on entities owning regulated 

manufacturing facilities may not be an appropriate measure of this impact and the results 

generated using the cost-to-revenue test may be misleading. These commenters pointed 

out that revenue does not capture the large overhead costs that some industries may 

require or the cyclical nature of operations in those industries. These commenters 

suggested EPA use other financial metrics that would take these factors into account such 

as earnings before interest, tax, depreciation, and amortization (EBITDA). 

	 Some commenters advised EPA conduct cost and economic analysis taking accounting 

the specifics of each individual manufacturing industry, implying that the current 

analytic approach does not do that. 

	 Riverkeeper stated that the cost-pass-through assumptions EPA made in the cost and 

economic impact analysis conducted for electric generators and manufacturing facilities 

are overly conservative. Specifically, for electric generators, EPA made the assumption 

of no cost pass through in the cost-to-revenue analysis conducted at the facility and entity 

level and the assumption of 100 percent cost pass through in the electricity rate and 

household impact analyses, are overly conservative. For manufacturing facilities, EPA 

assumed no cost pass through when modeling after-tax cash flow. Riverkeeper argued 

that in reality, some costs will be borne by consumers and some by complying 

facilities/entities. 

Annualization of Costs and Benefits

EPA notes that, to a large degree, the comments concerning EPA’s approaches for annualization 

of costs and benefits reflect misunderstanding of the differences between private cost, which 

EPA calculates from the perspective of the individual regulated facility, and social costs and 

benefits, which are calculated from the perspective of society, and reflect the total group of 

regulated facilities as a whole. In developing its analyses for the final rule, EPA followed wellestablished practice in annualizing different costs. The following responses to these comments 

clarify the reasons for the different cost analysis approaches and the resulting differences in the 

calculations. 

Claim of Inconsistencies in Annualization Periods

ACC claims there are differences in the annualization periods in the cost methodologies 

described in the TDD and in the EBA report. ACC is correct in noting differences in the 

annualization periods in the various analyses; however, the different periods reflect differences 

between private and social cost and the methodologies that EPA has used to calculate these costs. 

EPA is confident that its approach reflects widely accepted practices with respect to estimating 

these different costs. 

Essay 31 306 
For the economic analysis of the section 316(b) Existing Facilities Rule, EPA evaluated two 

different categories of the compliance costs. EPA evaluated private cost to measure the cost and 

impact to regulated facilities and permitting authorities, and evaluated social cost to measure the 

cost of the section 316(b) regulation to society. EPA’s choice of annualization periods reflects 

widely accepted methods of accounting for these costs and is consistent with direction from the 

Office of Management and Budget. 

As discussed in Chapter 3 of the EBA and the Economic Analysis for Final Section 316(b) 

Existing Facilities Rule (EA) reports, EPA calculated private costs at the level of the individual 

regulated facility and annualized the cost of compliance technology expenditures and other nonannually recurring outlays over various time periods based on (1) the estimated useful life of 

individual capital cost components or (2) the frequency of recurrence for other non-annual 

outlays (e.g., permit renewal). EPA discounted and annualized cost values using a 7-percent 

discount rate, which is an estimate of the opportunity cost of capital to society. In this analysis, 

the annualized period for a given technology outlay may be for as long as 30 years. 

The analysis of social costs differs in concept. Here, EPA looked over the full set of regulated 

facilities and explicitly accounted for the year in which each facility is expected to reach 

compliance, the duration of costs and benefits for each facility, recurrence of cost outlays. 

Because not all facilities are expected to reach compliance in the same year, the length of the 

analysis period and, correspondingly, the annualization period, is longer than the annualization 

period that would be used for an individual facility. As explained in Chapter 11 of the EBA 

report, EPA used a 50-year annualization period for the social cost analysis. This period includes 

(1) a 45-year compliance cost period during which costs are assigned on a year-explicit basis, 

and (2) an additional five-year benefit phase-down period. The 45-year compliance cost period 

starts at the promulgation year and reflects (1) the latest year in which any facility achieves 

compliance, and (2) the useful life of the longest-lived technology under any analyzed regulatory 

option. The benefit phase-down period reflects the expectation that benefits from reduced 

impingement and entrainment will continue for five years after compliance technology is 

assumed to have ceased functioning. 

In this analysis, EPA developed a year-specific stream of costs – which includes accounting for 

technology installation outlays, other non-annually recurring costs, and annually recurring costs 

in the year that they occur – and a year-specific stream of benefits. The year-specific stream of 

costs accounts for the longest life of any technology considered for the final rule – e.g., 30 

years – and provides for reinstallation of a compliance technology if it reaches the end of its 

useful life before the end of the 46-year compliance cost analysis period. In this way, the 

compliance technology life – whether, for example, 20 years, 25 years, or 30 years – is 

accounted for within the overall analysis and annualization period of 50 years. Thus, there is no 

inconsistency between the technology-specific annual periods used in the private cost analysis 

and the longer annualization period used in the social cost analysis. 

EPA then discounted the resulting streams of costs and benefits to the promulgation year, and 

annualized them over the 50-year analysis period. EPA discounted and annualized these values 

using both the 3-percent and the 7-percent discount rates. These discount rate values reflect 

guidance from the Office of Management and Budget (OMB) regulatory analysis guidance 

document, Circular A-4 (OMB, 2003; updated 2009). EPA used the same approach to estimate 

Essay 31 307 
total social costs for the final rule. However, for the analysis done in support of the final rule, the 

assumptions described above resulted in a 51-year annualization period due to a slightly longer 

(by one year) initial technology-installation window which resulted in a 46-year compliance cost 

period. EPA explained more explicitly the differences in the analytic approaches used to estimate 

private and social costs in EA report. 

The 50‐Year Annualization Period Used for the Proposed Rule Understates Costs;

Recommendation to Use 10‐Year Annualization Period Based on Congressional

Budget Office (CBO)

As described above, the 50-year analysis period used for proposed rule, and resulting 

annualization period, embeds information on the performance life of the various compliance 

technologies, including recurrence of technology outlays based on their useful life. As a result, 

EPA disagrees that the 50-year annualization period understates technology costs. For the final 

rule, EPA used a slightly longer analysis period of 51 years due to the assumption of a longer 

initial technology-installation period. 

In addition, EPA also does not agree that the CBO’s recommended 10-year analysis period is 

appropriate for the analysis. The CBO recommendation applies to analysis of public sector 

investments and pertains specifically to the life of financing for those investments – e.g., use of 

10-year bonds to finance public investments, even though the resulting asset may have a useful 

life that is longer than 10 years. In contrast, EPA’s analysis for the 316(b) rule focuses on the 

cost of compliance outlays and the length of time that the outlay is expected to provide the 

benefits to society through reduced impingement and/or entrainment of aquatic organisms. Using 

a shorter period for annualizing compliance costs than the period over which the compliance 

outlay will provide benefits, would overstate the cost of the compliance technology outlay – on 

an annualized cost basis – in achieving benefits on behalf of society. 

Use of Annualization Periods for the Proposed 316(b) Existing Facilities Rule

Analysis that Differ from the Periods Used in the Previous 316(b) Rulemaking

Analyses

EPA used the same methodology to calculate private costs of the remanded Phase II Rule, Phase 

III Rule, and the Proposed and Final Section 316(b) Existing Facilities Rules. Specifically, to 

estimate total private costs, EPA annualized each cost component over its useful life and used the 

7-percent discount rate for discounting and annualization. As described above, the annualization 

periods in the private cost analysis vary by useful life of the compliance outlay. The analysis 

concept and procedure are the same across the various 316(b) rulemaking analyses. 

For the analysis of social costs, EPA used a different annualization period for the proposed and 

final 316(b) existing facilities rule analyses from that used in the earlier Phase II and Phase III 

analyses. In the Phase II rulemaking analyses, EPA used the same annualization method and 

period in the social cost analysis as that used in the private cost analysis. This approach did not 

reflect the range of years in which facilities would achieve compliance, or the expected period 

over which benefits would decline after the compliance technology is assumed to have ceased 

functioning. As such, EPA concluded that this approach did not present as accurate or complete a 

Essay 31 308 
profile of social costs and benefits across all regulated facilities as a group as the approach used 

in the proposed and final existing facilities rule analyses. On this basis, EPA has determined that 

the approach used for today’s existing facilities rule analyses is appropriate because it represents 

further refinement, and hence an improvement, to the approach used for the Phase II rule 

analysis. 

Concerning the annualization approach used in the Phase III rulemaking analyses, EPA notes 

that the concept underlying the duration of the annualization period in the Phase III analyses is 

the same as that used in the proposed and final existing facilities rule analyses. However, the 

resulting annualization periods for social cost and benefits differ among the three analyses due to 

differences in the period during which facilities were expected to install compliance 

technologies: the technology-installation period for the final existing facilities rule is slightly 

longer than that used for the proposed existing facilities rule, which is longer than that used for 

the Phase III rule. As such, use of a different annualization period is appropriate and necessary 

because of the longer technology installation period. 

Use of 30‐Year Period for Modeling Benefits for the Individual Facility

EPA disagrees with EME’s claim that EPA should have modeled benefits associated with 

closed-cycle cooling installation over a shorter time period because of potential facility 

retirements resulting from the existing facilities rule. First, EPA’s analysis indicates there will be 

few retirements of generating capacity among electric power generators and no facility closures 

among manufacturing facilities. As a result, adjusting the annualization period for all regulated 

facilities based on unsupported speculation that some facilities might retire because of the rule, 

would understate the profile of benefits achieved for the much larger number of facilities that do 

not close because of the rule. Second, EPA notes that if it were to account for facility retirements 

in the benefits analysis, the appropriate treatment would be to recognize that the reduction in 

impingement and entrainment would in effect be permanent or even longer than assumed in the 

current analysis. 

Cost and Economic Impact Analysis Assumptions and Analytic Approach

Use of Sum of Facility‐Level Revenue for Entity‐Level Cost‐to‐Revenue Analysis

EPA disagrees with KCBPU that the Agency incorrectly used the sum of revenue from facilities 

owned by a given entity in its entity-level cost-to-revenue analysis. EPA did not. In fact, as 

discussed in Chapter 4 of the EA report, for that analysis, EPA used parent entity revenue values 

in that analysis. 

Underestimation of Cost Per Unit in Sales to Customers

EPA disagrees with KCBPU’s concern that it has underestimated total cost of compliance in 

general and compliance cost per unit in sales to customers in the Proposed Section 316(b) 

Existing Facilities Rule. EPA is confident that the analysis it conducted for the final rule reflects 

a careful consideration of the available information and its judgment reflects the Agency’s years 

of experience in evaluating economic data in developing its rules. In addition, because KCBPU 

did not present any detailed information to support its claim that EPA underestimated costs, EPA 

is unable to evaluate KCBPU’s particular situation. 

Essay 31 309 
Underestimation of the Rule’s Costs because of Failure to Account for Closing

Facilities

EPA disagrees with AMP that EPA did not properly account for generating unit retirements as 

the result of the 316(b) regulation. First, EPA notes that the 13 percent of manufacturing 

facilities referred to by AMP as estimated to retire because of the rule, are in fact projected 

baseline closures and not projected closures due to the 316(b) regulation. Second, EPA similarly 

identified projected baseline closure facilities in the electric power industry and excluded these 

facilities from the economic analysis in the same way the Agency did for manufacturing facilities 

baseline closures. This is appropriate because units that are projected to close for reasons other 

than this rulemaking will not incur costs associated with this rule. As such, EPA did not assign 

any compliance costs to these facilities. Specifically, EPA excluded from its costing estimates 

electric power facilities that have either already retired all of their steam generating units or will 

do so by 2021, according to the 2011 EIA-860 database, from cost and economic impact 

analyses. EPA notes that according to the 2012 EIA database, additional regulated electric 

generators either already retired all of their steam generating units or expect to do so by 2021. To 

the extent that EPA included these facilities in their cost and economic impact analysis of the 

final rule, the total national cost of the final rule is overestimated. 

AMP wants EPA to treat these baseline closures as a cost of the rule. As described in the 

preceding paragraph, the facilities cited by AMP are baseline closures and do not represent a cost 

or impact of the existing facilities rule. 

Finally, apart from the recognition of baseline closures, EPA used discounted cash flow analysis 

to assess which manufacturing facilities may close as the result of the final rule. For electric 

generators, EPA made this assessment as part of the electricity market analysis conducted using 

IPM. EPA reports any manufacturing facilities or electric generators closures that are estimated 

to occur as a result of the rule as an impact of the rule. 

Assertion that Cost‐to‐Revenue Analysis is Not an Appropriate Measure of Impact

EPA acknowledges that USS may be correct in its assertion that the EPA cost-to-revenue 

analysis does not fully account for different cost structures and operating margins across 

industries and individual firms/facilities within those industries. As described in the economic 

analysis reports for the proposed rule and final rule, however, EPA views the cost-to-revenue 

analysis as a screening analysis and does not use it to identify closures or other significant 

impacts from the rule. In addition, as also documented in the economic analysis reports for the 

proposed rule and final rule, EPA relies on more robust measures of economic/financial impact 

in its assessment of severe and moderate impacts among manufacturing facilities. Specifically, 

EPA uses discounted cash flow analysis of the change in facility business value for the 

assessment of severe impacts (closure), and interest coverage ratio and return on assets for the 

assessment of moderate financial impacts. The after-tax cash flow analysis of change in business 

value uses essentially the same financial concept as EBITDA, as recommended by USS. 

In addition, these analyses are based on detailed accounting statements received from facilities 

as part of the 316(b) survey, and thus reflect in a very detailed way the operating financial 

performance of actual manufacturing facilities that are expected to be subject to the Section 

316(b) Existing Facilities Rule. 

Essay 31 310 
Assertion that the Cost and Economic Impact Analysis Does Not Account for

Conditions in Specific Industries

EPA disagrees that the current cost and economic impact analysis does not account for the 

specific business and financial circumstances of individual manufacturing industries. The EPA 

is confident that its analyses adequately account for variations in business and financial 

circumstances. The current analysis accounts for specific business characteristics of industries 

and facilities in several ways: (1) as noted above, EPA uses specific business characteristics of 

regulated facilities based on survey data, (2) EPA adjusts those survey data to the present based 

on changes in industry-specific business conditions over time and also adjusts based on business 

cyclicality considerations, and (3) EPA uses appropriate economic/financial analytic methods 

based on discounted cash flow analysis and other financial metrics, which, as discussed above, 

account for different cost structures and operating margins across industries and individual 

firms/facilities within those industries. 

Assertion that Cost Pass‐Through Assumptions are Overly Conservative

EPA acknowledges Riverkeeper’s assertion that some aspects of the cost pass-through treatment 

may possibly overstate impacts to regulated facilities or to consumers. However, EPA does not 

view the cost pass-through treatment as yielding overly conservative results. As discussed in the 

Economic Analysis for the Final Section 316(b) Existing Facilities Rule (EA) report, EPA made 

the cost-pass-through assumptions in large part because of the substantial difficulty in 

determining the extent to which facilities will be able to pass their costs onto their consumers on 

a facility-by-facility basis – a virtual impossibility in an assessment of effects on 544 implicitly 

and explicitly analyzed regulated electric generators and 521 sampled and sample-represented 

regulated manufacturing facilities. EPA acknowledges, as stated in the EA report, that these 

treatments may overstate impacts – whether in the assumption that all costs would be absorbed 

by facilities in the facility impact assessment, or, in the alternative case, that all costs would be 

passed through to consumers for the assessment of rate impact to electricity consumers. 

However, EPA views these treatments as appropriate in order to ensure that impacts, whether to 

regulated facilities or to consumers, are not understated. Furthermore, EPA concluded that these 

analyses yield sufficiently accurate results for EPA’s assessment purposes. Even though facilityand entity-level impacts may be overstated due to the no-cost-pass-through assumption and 

impacts on electricity rates may be overstated due to the 100-percent-cost-pass-through 

assumption, these analyses show very small effects for the final rule. 

EPA further points out that the assumption of no cost pass-through for the manufacturing 

facilities impact analysis is based on detailed assessment of a range of economic factors for the 

industries that are expected to be primarily subject to the final rule. 

Finally, EPA agrees with Riverkeeper’s statement that compliance costs are likely to be shared 

by regulated facilities and by consumers. However, as stated above, given the uncertainty in 

estimating the distribution of compliance cost burden between regulated facilities and 

consumers, EPA views its approach as reasonable and appropriate for regulatory analyses. 

Essay 31 311 
Essay 35: Installation Downtime for Manufacturing and Non‐Electric

Power Generating Facilities

Introduction

A number of commenters state that EPA assumed no downtime for manufacturing facilities that 

would be subject to the rule as they install compliance technologies, and that this assumption is 

incorrect. These statements reflect incorrect understanding of information presented in the 

Economic and Benefits Analysis for Proposed Section 316(b) Existing Facilities Rule (EBA) 

report, and described again in the Economic Analysis for Final Section 316(b) Existing Facilities 

Rule (EA) report. As explained below and in these documents, in evaluating compliance costs, 

where appropriate, EPA assigned costs associated with downtime for manufacturers. In addition, 

a number of commenters stated that where EPA had estimated downtime, it had underestimated 

the costs to the manufacturer associated with that downtime. In general, they noted that EPA 

only included costs to purchase electricity and that it should have also included costs of 

associated manufacturing production downtime. 

History of the Development of Downtime Estimates for IM Controls for

Manufacturers

EPA’s determination of the length of possible downtime associated with various IM controls for 

this final rule is largely based on its prior analysis and evaluation that was done for the Phase III 

rule promulgated in 2006 which covers, among others, certain existing manufacturing facilities. 

See Chapter 5 of the TDD for the Final 316(b) Phase III rule. As explained there, the length of 

downtime, when incurred, is a function of which technology is being retrofitted and the size of 

the intakes. Because the technological approaches and the size of the intakes to which this final 

rule applies are not exactly the same as the Phase III final rule, EPA made slight adjustments to 

its earlier approach. For example, for the final rule, EPA developed downtime estimates for four 

ranges of intake flow rather than the three ranges in the Phase III rule. Also, for the reasons 

explained in Chapter 5 of the TDD for the Final 316(b) Phase III rule, EPA continued to 

conclude that it is appropriate to use a different methodology to estimate downtime for electric 

generators than for manufacturers for both the proposed and final existing facilities rule. EPA 

notes it did not receive any comments suggesting its overarching methodology for estimating the 

length of downtime for manufacturers was inappropriate. 

Length of Downtime for Installation of IM Controls

As explained above, EPA’s estimates of the length of compliance downtime for installing 

technologies to comply with the final existing rule’s IM standards are largely based on analysis 

from the final Phase III rule. With the exception of those commenters that inaccurately 

concluded that EPA assumed no downtime would be associated with IM compliance for all 

manufacturers, EPA did not receive any specific comments on its proposed estimates of 

downtime for manufacturers to install the various technological approaches to comply with the 

proposed existing facilities rule. As such, the methodology for today’s final existing facilities 

rule is the same as the proposed existing facilities rule. 

Essay 35 312 
                                                            

Also, as explained above, the length of downtime, when incurred, is a function of which 

technology is being retrofitted and the size of the intakes. In the cost analysis for compliance 

with the impingement mortality standards in today’s final rule, EPA assigned one of seven 

compliance modules to existing model manufacturing facility intakes, depending on site-specific 

conditions. See Chapter 8 of the TDD. These modules include the following technologies and/or 

combination of technologies: larger intakes, wedgewire screens, modified traveling screens, 

barrier nets, and variable speed pumps. After careful consideration of the installation 

requirements for each technology, consistent with its prior approach for manufacturing facilities 

(Phase III rule), EPA concluded that significant downtime would be required only for larger 

intakes or technologies that required modifications to the intake civil structures and/or 

modifications or tie-ins to intake piping. For the reasons explained below, of the five 

technologies in the cost modules, in most cases only larger intakes (associated with Cost Module 

3) and wedgewire screens (associated with Cost Module 4) would fit into that category as they 

would require modifications to the intake civil structures or piping. EPA generally assigned these 

two technologies to intakes that did not already employ traveling screens because EPA does not 

know whether traveling screens would be compatible with the existing intake structure without 

significant modifications. EPA chose to assign these two technologies because they are 

compatible with most intakes (with some restrictions for wedgewire) and attain compliance via 

the low velocity compliance alternative, which could be guaranteed through engineering design. 

EPA notes that the final rule includes seven compliance alternatives for the IM standards and 

EPA does not know whether manufacturing facilities that currently lack traveling screens will 

comply by increasing their intake size to accommodate low velocity screens and/or by adding 

wedgewire screens. EPA’s costing approach is likely conservative (high cost) because these 

approaches generally incur higher costs than other compliance alternatives, if available to the 

facility. Because EPA does not have data to predict which of the lower cost options (e.g., fish 

avoidance, barrier nets, flow reduction, etc.) would be available, EPA chose this more 

conservative approach. Thus, in many cases, this approach will likely result in overestimating 

both the compliance technology costs and downtime requirements for these intakes. 

As explained above, EPA concluded that upgrades of existing traveling screens, installation of 

barrier nets and variable speed pumps would result in no downtime. First, 45 percent of intakes 

at manufacturing facilities already employ traveling screens. In these cases, EPA assigned 

modified traveling screen upgrades only if the existing technologies were not deemed already 

compliant. This virtually guarantees that upgrades will involve only screen removal and 

replacement, which screen vendors have indicated could be performed in one to three days where 

fish troughs and new spray water piping are required (see the Phase II TDD). In most cases, 

these upgrades can be accomplished while an intake continues to operate, given that most facility 

intakes include more than one traveling screen. This allows sequential upgrading of the 

individual screens without shutting down the entire intake. EPA notes that existing screens 

already require periodic replacement/refurbishment and that operating contingencies for these 

activities should have already been established in most cases.55 At facilities where a continuous 

supply of water is required, various contingencies such as multiple parallel intake equipment, 

alternative sources of cooling water, and operational measures are often standard design 

components that ensure system reliability. 

55 For example, some commenters discussed the use of fixed screens as a temporary replacement for traveling 

screens that are being replaced or refurbished. 

Essay 35 313 
Upgrade of fixed speed pumps to variable speed pumps may take several days to several weeks 

depending on the project scope. However, most intakes utilize multiple parallel pumps, including 

backup pumps, which, like traveling screens, allow for one or more pumps to be taken out of 

service for maintenance/replacement while others continue operation. Thus, the relatively short 

duration, combined with availability of parallel and alternative equipment, make it very unlikely 

that variable speed pump technology upgrades would require any significant facility downtime.

No downtime is needed for barrier nets because they are independent of the intake structure and 

can be installed while intakes are operating.

Chapter 8 of the final TDD shows the number of model facility intakes that were assigned each 

cost module. Out of 735 intakes at manufacturing facilities, EPA assigned some combination of 

Cost Module 3 and/or 4 to 213 intakes. EPA assigned other cost modules to the remainder of the 

intakes. Because, as explained above, the technologies associated with these other cost modules 

would not require downtime, EPA appropriately did not include downtime for these intakes. 

For those intakes that were assigned some combination of Cost Module 3 and/or 4, EPA assigned 

installation downtime as indicated in the following table (reproduced from Chapter 8 in the final 

TDD).

Exhibit 8-4. Net Construction Downtime for Impingement Mortality Compliance 

Technologies

Cost 

Module 

Number1

Manufacturers (Weeks)

Flow < 

6,944 

gpm

Flow < 

6,944 

gpm

Flow 

6,944 to 

400,000 

gpm

Flow 

400,000 

to 

800,000 

gpm

Flow > 

800,000 

gpm

1 0 0 0 0 0

3 0 0 0 1 2

4 3 3 7 8 9

5 0 0 0 0 0

10.2

(3 & 5) 0 0 0 1 2

10.3

(1 & 5) 0 0 0 0 0

15 0 0 0 0 0

As described in Chapter 8 of the TDD, because the scope of construction projects at the lower 

flow facilities is much smaller than at larger flow facilities, where EPA determined downtime 

would likely occur, it projected longer shut down periods with larger flow facilities. EPA notes 

that it did not receive any specific comments on its proposed estimates of downtime for any of 

the flow levels for the cost modules, and as such, the downtime estimates for the final rule are 

the same as those in the proposed rule. 

Essay 35 314 
Costs of Downtime for Installation of IM Controls

Where EPA assigned downtime associated with installation of IM controls, EPA assigned costs 

for manufacturing facilities to purchase power from the grid. Because electricity generated onsite 

may be needed by many processes simultaneously, EPA concluded that many facilities would 

not be able to modify operations in a manner that would avoid impact on electricity generation 

during downtime. Therefore, downtime likely requires manufacturers to temporarily curtail 

electricity generation and to purchase power from the grid to continue operation. Where 

applicable, the cost of this temporary suspension of power generation includes the cost of 

purchasing replacement power plus the loss of any revenues received from selling power minus 

the variable costs of generating electricity. Commenters asserted that EPA wrongly concluded 

that they would incur only the costs associated with obtaining electricity associated with 

downtime. They asserted that EPA should similarly include costs of production downtime. As 

explained in more detail below, EPA disagrees with these comments as its record supports the 

conclusion that it is unlikely that an entire facility would shut-down and lose revenue associated 

with lost production of goods. 

Manufacturing facilities typically involve numerous sequential processes with varying water 

requirements for the processes and in many cases, additional water requirements for plant 

electric power and steam generation. Many large, manufacturing facilities not only have multiple 

types of processes, but also have multiple parallel process trains. Maintenance for the more 

complex operations may involve the shutdown of individual process trains or series of trains, but 

this leaves the remainder of the facilities in operation. The sequential processes often have 

storage capacity for the intermediate products, enabling such processes to continue operating 

while “upstream” processes are offline. As such, while the need for cooling water for the various 

manufacturing process steps is variable and flexible, the need for electricity which serves 

multiple processes simultaneously tends to be continuous and is often a major component of 

cooling water requirements. 

Nearly all manufacturing processes will require maintenance of production equipment and 

cooling water systems that will require interruption of the operation of equipment at various time 

intervals. Some manufacturers contacted by EPA did not generally report scheduled whole 

facilities shut-downs, which led EPA to conclude that they have vast experience in engineering 

alternate solutions to plant shutdowns during times of maintenance interruptions and major 

construction. In order to determine how a manufacturing facility might respond if faced with the 

potential need to enlarge intakes or install technologies that may require modifications to the 

intake civil structures, EPA collected information from eight manufacturing site visits and from 

phone calls to six manufacturing facilities. In general, facilities reported that they would likely 

use an approach or engineer a solution to minimize plant shutdown to the maximum extent 

possible. The record demonstrates that large, complex facilities, such as chemical manufacturing 

and steel mills, may seldom shut down the entire facility. But they do shut down individual 

process lines for extended maintenance periods and/or have redundant process equipment that 

can be rotated into service for maintenance or upgrades. This redundant process equipment often 

includes multiple intake screens and pumps. In cases where the cooling water flow from an 

intake may need to be interrupted, engineering solutions such as an alternative cooling water 

source, temporary bypass, or backup equipment may be employed. 

Essay 35 315 
EPA notes that implementation of the various contingencies that may need to be employed to 

minimize downtime costs as described above may require flexibility in the selection of the 

compliance alternatives and establishment of compliance schedules taking into consideration 

site-specific technical and operational limitations. The final rule was revised to address these 

special considerations by giving the Director discretion to establish different compliance 

schedules for manufacturing facilities where extenuating circumstances (e.g., lengthy scheduled 

outages, future production schedules) warrant establishing a different compliance date. See 

Section VIII of the preamble. Also, the final rule gives a facility greater flexibility in determining 

a compliance method, including a larger selection of IM compliance alternatives such as an 

alternative (system of technologies) that considers cumulative reductions of multiple 

technologies. This flexibility allows facilities to choose compliance alternatives that will 

minimize financial impacts such as lost production of goods. See Section IV of the preamble. 

EPA has concluded that these changes address the concerns expressed in public comments 

concerning compliance outages by minimizing impacts and by giving greater flexibility in 

scheduling compliance dates to allow for coordination of the timing of any outages caused by the 

installation of compliance technologies with production and long term maintenance schedules. 

Some examples from EPA site visits and industry contacts that support the assumptions used in 

EPA’s approach are described below. 

A steel mill noted that the blast furnaces are taken offline for maintenance for 10 days per year 

but only for one day at a time. However, the steel shops are batch processors and have 

opportunities for longer downtime periods. Many of the steel shops (including the smaller 

specialty shops) can operate independently of the remainder of the facility and can share 

materials with other sites to remain operational. They also reported that the facility uses modular 

(temporary) cooling towers when existing tower units are being repaired or replaced. (See DCN 

10-6551.) 

A chemical manufacturer explained that even though the entire facility rarely shuts down, 

individual process lines are periodically taken offline for maintenance and that there is sufficient 

redundancy within the facility to prevent widespread downtime; for example, multiple boilers 

can be rotated to continue to provide steam while any single one is out of service. Each 

cogeneration unit is taken offline once per year and other process units go offline as often as 

twice per year or as infrequently as every 2-3 years. (See DCN 10-6556.) 

A refinery stated that they were able to rebuild a collapsed cooling tower while the facility 

continued to operate. Facility representatives stated that the facility operated with a temporary 

cooling water tower and at a lower production capacity, but did not experience any plant-wide 

shutdowns as a result of the rebuilding process. The affected process unit was only taken fully 

offline during the tie-in. During the replacement of another old inefficient cooling tower, they 

were able to adjust production rates and share (or purchase) intermediate products to minimize 

any construction-related downtime. The majority of construction took place during a major 

maintenance outage of 6-9 months (unrelated to the conversion to closed-cycle cooling). Major 

outages typically occur every 4-5 years and last approximately 6 weeks, although a recent outage 

lasted 3 months due to low demand. Facility representatives stated if the extended outage had not 

occurred, much of the construction of the replacement tower would have been done while the 

Essay 35 316 
unit was operating. EPA has concluded that tie-in and startup activities should take no more than 

6-8 weeks to complete. (See DCN 10-6542.) 

A food processing facility stated that a planned replacement of the intake traveling screen would 

occur during their four day annual boiler inspection shut down. This 10 mgd average intake flow 

facility has one screen and two pumps but one is a backup pump. The facility has a backup 

intake that can provide an alternate source of water to the pumps if needed. (See DCN 12-6552.) 

In developing the Phase III rule, EPA also contacted several refineries and chemical facilities to 

inquire about experience with intake upgrades, availability of scheduled downtime and strategies 

they might employ. One facility, a refinery, had installed wedgewire screens without 

experiencing any downtime by sequentially working on one intake at a time. (See DCN 9-0043, 

EPA-HQ-OW-2004-0002-2184.) 

Finally, only one commenter on the existing facility rule, (Georgia Pacific, comment 2272), 

provided an actual estimate of downtime duration. This commenter indicated downtime was 

limited to no more than one day to modify an intake. 

Therefore, as a result of the small number of intakes that EPA projects would likely incur 

downtime, information from facilities that demonstrates multiple approaches, flexibility, 

redundant systems, contingency strategies, and engineering solutions, etc, EPA appropriately 

concludes for manufacturing facilities as a whole there will be no, or only very limited, lost 

production costs for facilities to install technology to meet the final rule’s impingement mortality 

(IM) requirement. 

Length of Downtime and Associated Costs for Installing Entrainment Controls

As explained in the preamble, the final rule establishes a BTA standard for entrainment that 

requires the determination of required entrainment reduction measures in a structured, sitespecific permitting proceeding. The BTA standard for entrainment requires that certain 

prescribed factors must be considered in the decision and must reflect the maximum reduction in 

entrainment warranted after consideration of relevant factors, including the number and types of 

entrained organisms. As such, the final rule does not establish a national numerical entrainment 

reduction performance standard nor identify a nationally applicable BTA technology. Also as 

explained in the preamble, while EPA considered costs in evaluating technologies as BTA on a 

national basis, costs were not dispositive. Rather, EPA was unable to identify a technology or 

combination of technologies that is BTA for entrainment on a national basis either because they 

were not uniformly effective and/or not technically available on a national basis. Therefore, 

comments related to potential costs associated with potential downtime to install entrainment 

controls, including closed-cycle cooling, are not relevant to EPA’s national BTA entrainment 

determination. 

However, EPA did consider options that would have subjected approximately 90 percent of the 

cooling water intake flows on a national basis to entrainment requirements based on closed-cycle 

cooling. For generating facilities, EPA has assumed that the duration of an outage for a closedcycle retrofit would average about 8 weeks and that costs for lost generation would be based on 

the additional net 4-week period that a generating unit would be shut down if the retrofit were 

scheduled to occur concurrently with a scheduled maintenance outages that typically lasts about 

Essay 35 317 
4 weeks. At proposal, EPA assumed that, unlike generating facilities, there would be no 

downtime costs for closed-cycle cooling retrofits at manufacturing facilities due to the fact that 

manufacturers are often more segmented in their production and use of cooling water and are 

therefore more likely to be able to shut down individual intakes or process lines without 

interrupting the production of the entire facility. However, several public comments noted that, at 

some facilities, generating systems provide electricity or electricity and steam (cogeneration) to 

many processes within the facilities and that interruption of the cooling water source and thus the 

operation of generating/cogenerating system could impact facilities production. In response, for 

today’s final rule, EPA revised the compliance cost methodology used in evaluating closed-cycle 

cooling costs under Proposal Options 2 and 3 to include downtime and associated costs for 

manufacturing facilities. Where EPA estimated downtime to retrofit to closed-cycle, it applied 

costs in a similar manner as downtime applied to IM technologies. That is, as its record 

demonstrates, the overall manufacturing process will not suffer significant production losses and 

that the effect of downtime is primarily associated with the effect on the generation system. 

These costs are assessed as the equivalent cost of replacement electricity and lost revenue for 

offsite sales of excess generation. 

For closed-cycle retrofits at manufacturing facilities, EPA applied a downtime duration of 4 

weeks. This is consistent with the downtime EPA included for non-nuclear generating facilities, 

but the value reflects a somewhat different basis. At generating facilities, most of the power 

generated is distributed offsite and lost power due to downtime is replaced by other generating 

units and facilities via the grid. However, most of the power/steam generated onsite at 

manufacturing facilities is used onsite. This configuration requires that interruptions to the 

operation of the generating system must be accounted for using various contingencies including: 

offsite replacement sources (e.g., utility grid connections); redundant (spare) generating capacity; 

temporary replacement generating units; or temporary replacement cooling water sources. The 

availability of these various contingencies varies by facility type and location and insufficient 

data was available to enable EPA to assess availability of different contingency methods. Rather, 

EPA developed a downtime value to represent a nationwide average. Because generating units at 

manufacturing facilities will require periodic maintenance, it is reasonable to assume that many 

manufacturing facilities will have included in their design and operating schedule consideration 

of this contingency by including sufficient spare generating capacity, access to replacement 

power through utility connections, or planned outages. This would allow for rotating 

maintenance downtimes for individual generating units, at least during periods of reduced 

demand. At many of these facilities, the downtime costs will be minimal because the closedcycle retrofit (which EPA estimates may take up to 8 weeks) can be performed on individual 

generating units in a manner that avoids interruption of the supply of electricity and steam. EPA 

expects that a large portion of manufacturing facilities fall within this category. For those 

facilities that rely upon replacement electric power from the grid, the costs would be for 

replacement power for the generating unit downtime duration that exceeds the normal downtime 

for generating unit maintenance. For power generating units this is four weeks, which EPA 

expects to be reasonable for these manufacturing facilities as well. EPA recognizes that for those 

facilities that cannot rely upon multiple generating units and excess capacity or replacement 

power from offsite, costs for replacement of electricity and steam generation capacity or 

replacement cooling water for the estimated 8-week retrofit duration may be necessary. While 

the cost of these temporary solutions may exceed the costs for replacement electricity, based on 

site visit data and the number of relevant comments received, EPA concluded that such facilities 

Essay 35 318 
are in the minority and that the aggregate downtime, when balanced against those facilities 

where EPA expects the downtime will be zero, should result in an overall facility downtime 

(average across all facilities) that is similar in magnitude to the 4-week downtime. Therefore, 

because EPA was unable to distinguish which facilities would utilize the different types of 

contingency methods described here, EPA applied the 4-week downtime costs to all 

manufacturing facilities when evaluating compliance options that involved a closed-cycle 

cooling retrofit. 

EPA notes that because costs were not dispositive in rejecting closed-cycle cooling as BTA on a 

national basis, in instances where EPA may have underestimated downtime associated with 

options based on closed-cycle cooling for manufacturers, it would not have altered EPA’s 

determination. Also, where facilities are providing costs for entrainment controls for their sitespecific BTA entrainment determination, if they can demonstrate downtime would be required 

for their specific site, the facility can include downtime related costs and the Director may 

consider them as part of the site-specific BTA entrainment determination. 

Industry or Facility‐Specific Downtime

A commenter stated that EPA has misinterpreted the “downtime” for facilities trying to meet the 

impingement standards, noting that while their cogeneration plant can sustain downtime for one 

of the boilers, they must be able to continuously withdraw water to supply steam to customers, 

including a hospital. They note that the cost of replacement city water is exorbitant and 

depending on water utility demand at the time, replacement water may not be available. The 

commenter provided no details regarding their intake design or under what circumstances intake 

flow would need to be interrupted. EPA understands that facilities with small intakes, 

particularly those with only one screen, may not have a backup or second screen to use when 

intake or screen modifications are required. However, EPA concluded that in virtually all 

circumstances, the time needed to modify the intake to meet impingement requirements will be 

brief and that solutions such as temporary screens or alternative water sources can utilized. In 

this particular case, the commenter’s concern about potential inability of city water capability to 

meet demand can be resolved by appropriate scheduling because the Director will have 

flexibility in establishing the compliance date; the purchase of city water, if necessary, can be 

scheduled during periods when both the city water demand and cogeneration steam demand are 

lowest. Because water will likely only be needed for a relatively short duration, the cost should 

not be excessive. In other cases, where an alternative source is not available, engineering 

solutions such as temporary intakes and bypass pumps may be employed. EPA has provided 

flexibility and options for IM compliance in the final rule so that facilities such as this one would 

have a range of options to choose from. 

A commenter stated that their facility cannot lose power for greater than 12 hours without very 

high restart cost, which was not considered by EPA. They also state that they cannot purchase 

enough power without extensive investment in infrastructure unless they radically curtail 

production at huge costs. This example was provided in support of their statement that EPA 

should provide a more flexible approach in regulating industrial facilities. EPA notes that the 

commenter suggests that the scenario that would potentially create such an interruption is a 

requirement to replace the intake structure. The final rule includes revisions that provide for 

additional alternatives for complying with the BTA IM standard that do not require replacing the 

Essay 35 319 
intake structure (see Section IV of the preamble.) The commenter provided no information to 

suggest that any of the other options are not available and that such a shutdown would be 

necessary nor do they provide any information concerning the potential cost of infrastructure 

investment. In the final rule, EPA has provided the Director more flexibility in determining 

compliance scheduling and more flexibility through additional options for IM compliance. As a 

result, given the alternatives, facilities would have many options to choose from and greater 

ability to schedule compliance upgrades to accommodate their specific circumstances. 

Another commenter argued that downtime costs for petroleum refineries would be relatively 

higher than downtime for power plants because facilities often rely on a single intake for 

multiple process units and are often located in highly developed areas where modifying an intake 

may be more complex and time for making modifications may be limited. During development 

of the Phase III Rule, EPA obtained information from three refineries concerning scheduled 

downtime, experience, and potential solutions that might be employed to address the possibility 

of intake operations interruptions associated with intake technology retrofits (see DCN 9-0043 in 

the Phase III Final Rule). EPA found that two refineries did have scheduled, whole facility 

downtime but only infrequently every 4 to 6 years, but that both had two intakes that could be 

retrofitted independently without a need for downtime. The third refinery did not normally 

schedule a whole facility shut-down but had already installed wedgewire t-screens without the 

need to shut down production by connecting the screens to each pump one at a time. This 

information supports EPA’s conclusion that downtime for refineries should be negligible. 

Other Downtime Comments

Some commenters state that facilities may not be able to purchase electricity for a number of 

reasons, such as insufficient transmission or step-down transformer capacity, and that steam will 

be available for purchase only in rare instances. For example, a commenter states that because its 

facility is a stand-alone facility, it cannot purchase enough power, without substantial investment 

in infrastructure, unless production is curtailed. EPA acknowledges that it may not be possible in 

each and every case for facilities to purchase power. But as discussed above, facilities have 

several methods for replacing power or avoiding the need to replace power. Because EPA does 

not have the ability to say with certainty which facilities may have to purchase power and which 

facilities may have alternative ways to avoid needing to purchase power, as explained above, 

EPA included costs to purchase power where it estimated downtime for manufacturers. 

However, EPA also concluded that revisions to the final rule that provide additional compliance 

flexibility will enable many manufacturers to minimize or avoid downtime altogether and that 

those requiring downtime or other engineering solutions are in the minority. As such, the 

estimated costs for full power replacement represent a middle ground between facilities where no 

power replacement will be necessary and those where the cost of additional engineering 

solutions may be necessary. EPA concluded that this approach is reasonable because these overand under-estimations of costs will tend to balance out in the overall national estimate. 

Some commenters argued that the measures EPA suggested could be used to avoid productionrelated downtime impacts – such as building up inventory in advance – are costly, and that 

avoiding production losses that would otherwise occur during downtime does not eliminate 

adverse economic impacts. However, these commenters failed to support this very general 

statement with details on the potential costs. As stated, there are a number of possible ways for 

Essay 35 320 
facilities to avoid downtime and while any one option may not be available for a given facility, 

EPA concluded that facilities will be able to avoid downtime for manufacturing processes using 

one of the above methods. 

Commenters point to EPA’s statement, “In EPA’s extensive experience with manufacturers 

while developing effluent guidelines, EPA found manufacturers are generally able to shut down 

individual intakes for specific process lines, use inventory approaches such as temporary 

increases of intermediate products, and develop other workarounds without interrupting the 

production of the entire facility” (see 76 Fed. Reg. at 22,214) and state that EPA’s support for 

this statement is illogical. Commenters state that EPA’s development of effluent guidelines has 

not involved any consideration of intake structures or their modification. EPA disagrees that its 

historical understanding of plant operations obtained during development of effluent guidelines 

is not relevant or transferable to the water requirements associated with an intake structure. 

While EPA did not specifically focus on water intakes during the development of its 

development of effluent guidelines for over 56 industrial categories and over 450 subcategories, 

in the course of developing the Phase II and Phase III rules for manufacturing facilities and 

today’s final rule, EPA visited cooling water intake structures and associated manufacturing 

operations at more than 50 power plants and manufacturing sites. During these visits, the EPA 

gathered information on the intake technologies and cooling water systems. EPA also obtained 

operating information concerning process operating schedule and water use for many individual 

industrial processes. Such information is useful in assessing the source, volume and character of 

individual waste streams and potential management strategies such as pretreatment and source 

reduction. EPA notes that the implementation of wastewater management strategies also requires 

consideration of process interruptions due to technology retrofits. EPA’s engineering judgment, 

developed over years of the ELG development process and consideration of 316(b) requirements, 

supports its conclusions on downtime and associated costs to the industry. 

Essay 35 321 
Essay 36: Employment Effects Analysis

Overview of Comments

The comments concerning potential employment effects range quite widely with some 

commenters offering favorable assessments of the employment effects analysis while other 

commenters raised various issues about the analysis or its findings. Comments include: 

	 Argument that EPA did not present quantified estimates on the rule’s potential 

employment effects and thus did not meet the requirements of executive orders for 

regulatory analysis. 

	 Some commenters expressed concerns with aspects of EPA’s approach for estimating 

employment effects, including in particular concerns about how EPA accounted for the 

effect of potential increased electricity rates on employment throughout the general 

economy: 

o	 Assumption of full cost pass-through in estimating potential electricity price 

increases. 

o	 Use of more than one analysis case for the assumed elasticity response to 

electricity and electricity-dependent product price increases. 

	 Recommendation that EPA look at previous empirical studies of potential employment 

effects associated with electricity price increases. Some commenters claim that other 

studies found higher employment losses than estimated by EPA in its analysis for the 

proposed rule and other options considered. Other commenters argue the opposite. 

	 Recommendation that EPA estimate job effects in the electric power sector based on 

potential loss in electric generating capacity from the market model analysis and the 

employment intensity of electric power generation. 

	 Criticism that EPA did not account for employment losses in baseline closures in 

Manufacturers. 

	 Argument that Option 3 (all cooling towers in the proposed rule analysis) would result in 

the least adverse overall employment effect and would achieve the most positive nearterm employment and economic effects, and that this factor would support selecting all 

cooling towers as the basis for the 316(b) existing facilities rule. 

	 Arguments supporting the existing facilities rule based in part on the potential 

employment requirements for achieving regulatory compliance. 

General Response

Throughout the development of 316(b) regulations, EPA has conducted extensive analysis of the 

economic effects of the actions it considered and provided that information to the public. In 

addition, as required by Executive Orders 12866 and 13563, EPA assessed the potential 

employment effects of the 316(b) regulation at the time of the proposed rule in 2011 and now 

again as it promulgates the Final Section 316(b) Existing Facilities Rule (final rule). 

Essay 36 322 
                                                            

 

EPA used different methods in assessing employment effects for the proposed and final rules, 

both of which provide useful insight into the rule’s potential employment effects.56 As 

documented in Chapter 9 of the Economic Analysis for Final Section 316(b) Existing Facilities 

Rule (EA) report, EPA notes that the analysis of employment effects presents significant 

challenges due to the multiple ways in which regulatory requirements may affect employment. 

To illustrate, on the one hand, the installation of equipment to achieve compliance with a 

regulation may result in employment increases, particularly in the near term during the period in 

which regulated facilities meet compliance requirements. However, the costs incurred for 

installing and operating compliance technology may lead to price increases in affected industries. 

Looking longer term, these price increases may lead to reduced purchases of the output of these 

industries, and, as a consequence, reduced production activity and employment. At the same 

time, environmental regulations may have other employment effects as industries adjust their 

production processes in response to regulatory requirements, which may lead to increases or 

decreases in employment. Finally, compliance response actions in the directly regulated 

industries may affect employment in economically linked industries. Again, these effects may be 

positive or negative, will likely vary over time, and involve considerable uncertainty in their 

estimation. 

Given the multiplicity of factors affecting employment, the conflicting character of their effects, 

and the likelihood that effects will vary substantially by industry, EPA concluded that the 316(b) 

regulation could have a range of employment effects – overall increases or decreases in 

employment, and with varying effects over time. Ultimately, however, the EPA concluded that, 

in no event, would these employment effects be so substantial that they would change EPA’s 

decision about what standards it should adopt for the final rule. In this regard, the comments 

concerning the employment effects analysis – which to a large degree focus on some element of 

EPA’s analyses or suggest alternative approaches and data – are useful in furthering the 

academic discussions of how to assess potential employment effects, but were not dispositive in 

EPA’s determinations for the final rule. 

Moreover, the available evidence from peer-reviewed econometric studies that use a structural 

approach to estimating the employment impacts of environmental regulations, applicable to 

overall net effects in the regulated sectors, converge on the finding that such effects, whether 

positive or negative, have been small and have not affected employment in the national economy 

in a significant way. Based on this evidence and additional information on regulated sectors 

impacted by the rule presented in Chapter 9 of the EA, EPA expects that the final rule’s 

employment impacts are not likely to be substantial. 

EPA’s responses to the employment effects comments follow below. 

Failure to Perform a Quantitative Employment Effects Analysis

EPA disagrees with some commenters’ claim that EPA did not conduct quantitative employment 

effects analysis for the existing facilities rule. For proposal, EPA presented a quantitative 

analysis of employment effects in Chapter 10 of the Economic and Benefits Analysis for the 

Proposed Section 316(b) Existing Facilities Rule (EBA) report. 

56 See Economic and Benefits Analysis for the Proposed Section 316(b) Existing Facilities Rule (EBA) report, 

Chapter 10, and Economic Analysis for the Final Section 316(b) Existing Facilities Rule (EA) report, Chapter 9. 

Essay 36 323 
                                                            

For the final rule, EPA approached its analysis of employment effects differently than for the 

proposed rule. Specifically, unlike for the proposed rule, for the final rule, EPA did not estimate 

quantitative employment impacts but instead included only a qualitative discussion. In 

considering an approach for the final rule, the Agency concluded that the methods used at 

proposal were not sufficiently robust, largely because they relied on an input-output analysis that 

assumed fixed production relationships and used historical data to estimate the labor and other 

inputs required for compliance with the rule. Since publication of the proposed rule, EPA has 

concluded that an input-output analysis-based approach is inappropriate for assessing 

employment impacts of national-level regulations. Input-output models are static, do not include 

prices, and assume the supply of all inputs is inexhaustible. They do not model a wide variety of 

adjustments that are expected to occur over time, such as changes in production processes, 

technology or trade patterns.57 After reviewing the public comments EPA received on the 

proposed rule, the Agency concludes that the commenters have not identified any specific 

improvements to the employment analysis of the proposed rule. Thus, because EPA does not 

have a robust methodology to calculate quantitative employment effects, nor did commenters 

provide alternatives, the final rule EA includes a qualitative discussion highlighting the variety of 

potential adjustments in the labor market that may follow the rulemaking. 

For the final rule, EPA sought methods that would circumvent the shortcomings of the 

methodology used for proposed rule. As discussed in Chapter 9 of the EA report, however, 

because of the complexity of factors through which an environmental regulation may affect 

employment, the myriad uncertainties in assessing economy-wide, long-term employment effects 

of a regulation, EPA conducted only a qualitative assessment of employment effects for the final 

rule. Because EPA does not currently have a sufficiently robust methodology to quantitatively 

assess the impact of today’s final rule on employment, the qualitative employment effects 

analysis undertaken for the final rule is appropriate. 

Analysis of Electricity Rate Effects on Employment

Some commenters disagreed with EPA’s assumptions and methodology for assessing the effect 

of increased electricity rates on employment. Criticisms included the assumption of full cost 

pass-through in estimating potential rate effects, and the use of more than one analytic case for 

assessing potential effects on businesses from rate changes. EPA points out, as noted above, that 

there are myriad uncertainties in estimating employment effects and that estimated effects could 

range from positive to negative impacts overall, and with varying effects over time. At present, 

the EPA lacks a method basis for quantitatively estimating employment effects, and 

commenters’ concerns fall within the range of EPA’s expected uncertainty for employment 

effects estimates. 

In addition, as discussed above, EPA notes that it approached consideration of employment 

effects for the final rule differently than for the proposed rule. Specifically, in considering an 

approach for the final rule, the Agency concluded that the methods used at proposal were not 

sufficiently robust, largely because they relied on an input-output analysis that assumed fixed 

production relationships and used historical data to estimate the labor and other inputs required 

for compliance with the rule. For the final rule, EPA did not estimate the change in employment 

57 For a discussion of input-output models see Chapter 8 of the EPA Handbook on the Benefits, Costs, and Impacts 

of Land Cleanup and Reuse (2011). 

Essay 36 324 
quantitatively; instead, the Agency assessed qualitatively the many ways the final rule may affect 

employment levels in the directly affected industries, the environmental protection sector, and 

the U.S. economy overall. See EA Chapter 9 for discussion of the final rule’s potential 

employment effects. 

As stated above, in EPA’s view, in the absence of a robust quantitative employment effects 

methodology and adequate data, the qualitative employment effects analysis undertaken for the 

final rule is appropriate to produce an informed regulatory result. 

Use of Other Methodologies and Data for Performing Employment Effects Analysis

As stated above, EPA recognizes the importance of assessing the employment effects of 

environmental regulations, and acknowledges commenters’ recommendations for potential 

improvements in the methods and data for assessing employment effects. At the same time, EPA 

disagrees with some of the proposed approaches for assessing employment effects. 

Recommendation to Use the Labor Intensity Coefficient Developed from NERA Study

for the Employment Analysis

One commenter recommends using a labor intensity coefficient from a NERA study (1 job per 

28.8 MW of capacity) in conjunction with estimated capacity losses as the basis for estimating 

potential employment losses in the electric power industry due to the 316(b) existing facilities 

rule. EPA disagrees with the commenter’s recommendation for several reasons. First, in making 

the calculations, the commenter used capacity losses estimated for the group of regulated 

facilities only, and not for the overall electricity market. Second, the commenter accounted only 

for the amount of retired capacity and failed to account for the amount of capacity gained 

through new builds. Given that in the context of the Electricity Market Analysis EPA conducted 

using the Integrated Planning Model (IPM®), when looking at the overall electricity market, the 

retired capacity is essentially replaced by the equivalent amount of new capacity, the overall net 

change in jobs, if any, is likely to be small at the level of the electricity market. 

Because the commenter did not provide the referenced study conducted by NERA, EPA was 

unable to verify the assumptions/conclusions/analyses underlying the fixed labor intensity 

coefficient. Therefore, EPA could not determine whether this coefficient can be applied to an 

increase in capacity, to estimate increased jobs, just as the commenter applied it to retired 

capacity to estimate job losses. Assuming this labor intensity coefficient can be used regardless 

of the direction of changes in capacity, the net change in jobs due to the final rule estimated 

using the proposed methodology would be small. 

Recommendation That EPA Estimate Job Effects in the Electric Power Sector Based

on Potential Loss in Electric Generating Capacity from the Market Model Analysis

In its analysis for the final rule, EPA did not specifically assess the employment effects from 

early retirement of generating units for several reasons. First, only 23 units (out of 14,920 

generating units analyzed in IPM) accounting for 0.1 percent of total market capacity, are 

projected to retire early due to the final rule. Second these retired units do not contribute 

significantly to electricity supply in the baseline case, with 15 units having a capacity utilization 

Essay 36 325 
rate of zero, seven units with less than 11 percent, and only one unit with substantial capacity 

utilization of approximately 66 percent. Third, some jobs will be gained as the result of new 

generating units being constructed and/or increased utilization of existing units to replace the 

relatively small amount of electricity otherwise generated by the units projected to retire early. 

As a result, EPA does not expect significant, if any, job losses from capacity effects associated 

with the final rule. 

Recommendation to Use Results from Other Studies in the Employment Effects

Analysis

EPRI suggested that EPA compare the results from its employment effects analysis with results 

from other, empirically based studies. As an example of an empirical study, EPRI referred to a 

study conducted by the National Bureau of Economic Research (NBER) that found that job 

losses resulting from electricity price increases could be “roughly double” EPA’s employment 

effects estimated in support of the proposed rule. Other studies investigating the relationship 

between electricity prices and employment in the United States that EPRI mentioned are: Jaffe et 

al. (1995), Berman and Bui (2001), Greenstone (2002), and a study conducted for the National 

Bureau of Economic Research, Deschenes (2010). 

Prior to deciding on its approach for the final rule, EPA reviewed various studies looking at 

employment effects, including those cited above. These studies revealed a complex array of 

factors through which an environmental regulation may affect employment, and discuss myriad 

uncertainties in assessing economy-wide, long-term employment effects of a regulation. These 

studies support EPA’s conclusion that its proposed quantitative methodology was not sufficiently 

robust. 

Chapter 9 of the EA report provides a substantial discussion of the ways a regulation can affect 

employment in the directly affected and other industries and resulting uncertainties in 

employment effects assessment. EA Chapter 9 also describes the considerable complexity in 

estimating the employment effects of a regulation and issues in the currently available 

approaches for estimating these effects. In EPA’s view, the development of a comprehensive and 

sufficient approach for quantitatively estimating employment effects remains an ongoing 

challenge, which EPA is addressing via a carefully structured review of methods for analyzing 

the economy-wide effects of environmental regulations, including employment effects. Until 

completion of this effort, and associated development of improved methods for analyzing 

employment effects, EPA will not provide estimates that, in EPA’s view, are based on an 

inadequate or insufficiently validated methodology. 

Failure to Account for the Employment Loss in Baseline Closure of Manufacturers

Facilities

EPA acknowledges the commenter’s comments that the Agency did not assess employment 

effects resulting from closure of the 13 percent of regulated manufacturing facilities that EPA 

estimated as baseline closures at proposal. However, EPA disagrees that EPA should have 

accounted for these employment effects. The purpose of the cost and economic impact analysis 

is to assess the impact of the rule. Any employment effects in baseline closure facilities would 

not result from the rule, but would result from significant economic/financial weakness, and 

Essay 36 326 
likelihood of closure, among the baseline closure facilities, independent of the requirements of 

the 316(b) existing facilities rules. 

Failure to Recognize that Proposal Option 3 Would Result in the Least Adverse

Impact on Employment

One commenter (Riverkeeper) argued that EPA should have (1) accounted for the findings at 

proposal that Option 3 (all cooling towers) would have the least adverse impact of employment 

and could boost the economy in the near-term, and (2) relied on those findings in selecting “all 

cooling towers” as the basis for the regulation. As described above, EPA views the employment 

effects analysis undertaken at proposal, and now for the final rule, as involving considerable 

uncertainties. Moreover, regardless of the methodology, EPA concluded that the existing 

facilities rule will not have a substantial impact on employment – positive or negative – and does 

not consider the rule’s potential employment or total economic effects a key factor in defining 

the final rule. Finally, EPA notes that it did not find employment effects to be dispositive in its 

decision to reject closed-cycle cooling on a national basis as BTA. Rather, EPA rejected closedcycle cooling based on three factors: land availability, air emissions, and remaining useful life. 

See the final preamble for additional information. 

Arguments Supporting the Existing Facilities Rule Based on Potential Employment

Requirements

As described above, EPA assesses that the final rule could have a range of employment effects – 

overall positive or overall negative – and with a varying profile over time; however, none of the 

analyses undertaken, or information provided by commenters indicate these effects would be 

substantial. 

Essay 36 327 
Essay 37: Adverse Impacts on National, State, and Local Economies

The commenters expressed a range of concerns regarding the potential adverse impact of the 

316(b) regulation on the overall economy, at the national, state, and local levels. Commenters 

also argue that this regulation is likely to impede economic recovery both at the national level 

and in the individual States represented by the commenters. Commenters’ arguments include: 

	 Given that the current nationwide recession forced many people out of jobs and many 

companies, and state and local governments into financial distress, EPA must ensure that 

new regulations are “thoroughly necessary, justified, and produce maximum net benefits” 

for each regulated facility. These commenters believe that the 316(b) regulation does not 

yet meet these standards. 

	 High compliance costs of the 316(b) regulation will lead to premature retirements of 

generating facilities, reduced electricity availability, higher costs of manufactured goods, 

and higher electricity costs to consumers at a time when they can least afford them 

without providing corresponding benefits. 

	 The 316(b) regulation by itself and combined with other recently promulgated and 

currently pending regulations, will slow economic recovery. 

	 The very high cost of cooling towers would lead to higher electricity rates for State 

residents and present reliability concerns. 

EPA acknowledges commenters’ statements about the state of the U.S. economy overall and of 

certain States, in particular. However, EPA disagrees that the 316(b) regulation will adversely 

affect the national and State economies. EPA notes that some of these comments were made 

specifically in the context of the higher cost and operating impact of a regulation that would 

require facilities to meet BTA based on entrainment mortality technology – i.e., cooling towers. 

The final rule establishes a BTA standard for impingement mortality based on the performance 

of modified traveling screens with a fish return system. The rule provides seven alternatives for 

complying with the standard, only one of which is cooling towers (for details on these 

requirements, please see the preamble for the final rule). Further, the final rule does not establish 

a BTA standard for entrainment that requires installation of cooling towers or achievement of 

equivalent flow reductions. Therefore, to the extent that commenters’ concerns about the 

potential effects of the final rule on the national, State and local economies, including effects on 

the economic recovery and electricity rates, are premised on the assumption of a nationallymandated requirement for cooling towers, the assumption is in error. 

The BTA entrainment standard for the final rule requires the development of BTA entrainment 

controls for each facility subject to the rule in a site-specific permitting proceeding. In that 

proceeding, the Director must consider specified factors in determining required controls. The 

final rule specifies a range of information that must be submitted and considered by the Director 

as part of the NPDES permit application. Among items and where applicable, this includes 

entrainment performance studies, a comprehensive technical feasibility and cost evaluation 

Essay 37 328 
study, a benefits evaluation study, and a non-water quality environmental and other impacts 

assessment. See additional discussion in section VI.I of the final preamble. 

EPA estimated nationwide total annual costs for the final rule accounting for facilities’ 

compliance costs to meet the BTA standards. This includes costs to comply with the IM 

performance standards and the study/reporting requirements associated with the site-specific 

permitting framework established for entrainment. While EPA acknowledges that some facilities 

will likely incur costs to comply with site-specific entrainment determinations as a result of this 

framework, EPA could not reliably predict the outcome of such proceedings, and therefore, the 

cost of any entrainment control measure a facility might be required to implement. See Essay 14 

and 15. Also see Essay 31and Essay 39. The EPA estimates that the total annual cost of the final 

rule, including costs of complying with the BTA impingement standard and costs to conduct the 

required permit application studies and gather and submit the additional data and information, is 

between $275 million and $297 million, depending on the discount rate. This is extremely small 

in relation to the total economy – less than 0.01 percent of GDP in 2012. Accordingly, EPA 

disagrees that the final rule will impede the economic recovery. 

As stated above, the final rule does not establish a BTA standard for entrainment that requires 

installation of cooling towers or achievement of equivalent flow reductions and EPA did not 

estimate the cost of requiring cooling towers everywhere for the final rule. However, in the EA 

report for the final rule, EPA did estimate the cost for requiring entrainment control measures, 

e.g., cooling towers, at all facilities with 125 mgd or greater (Proposal Option 2), which account 

for 90 percent of actual flows. The total annualized cost for that option would be approximately 

$3.6 billion at the three percent discount rate, which is under 0.03 percent of GDP in 2012 and 

would not be large enough to adversely affect the economic recovery. 

In addition, EPA does not agree that the final rule will lead to consequential early retirements of 

electric generating capacity. As described in Chapter 6 of the EA report, EPA found that the final 

rule will lead to a very modest increase in capacity retirements – less than 0.1 percent of total 

baseline capacity at the national level and no more than 0.8 percent of baseline retired capacity in 

any North American Electric Reliability Corporation (NERC) region, projected to occur in TRE. 

EPA assesses that these very small retirements are inconsequential relative to total national and 

regional generating capacity. As a result, the final rule will not significantly affect electric supply 

reliability – both nationally and by NERC region. 

Further, EPA also disagrees that the final rule will have a significant adverse impact on 

electricity rates. As documented in Chapter 4 of the EA report, EPA estimates very small 

electricity rate increases in general and by consumer group, and very small increases in annual 

household bills. For the final rule, under an assumption that all compliance costs would be 

passed through to consumers in electricity rate increases, EPA estimated that rates would 

increase by approximately one one-hundredth of a cent per kWh across the United States. On a 

percentage basis, the estimated rate increases are comparably small, both nationally and by 

region: the estimated percentage increase in electricity rates averages 0.09 percent nationally, 

with the largest increase by region being only 0.15 percent. EPA concludes that these small 

increases are reasonable in relation to the Clean Water Act-mandated environmental 

improvements achieved by this regulation. 

Essay 37 329 
Finally, EPA notes that the final rule does not specify a timeline for compliance with any 

entrainment requirements that result from the site-specific determination. Instead, the rule gives 

Permit Directors authority to establish compliance schedules and specific compliance 

requirements based on identified concerns, if any, over capacity losses and electric supply 

reliability. Further, this authority given to Permit Directors to establish compliance schedules and 

compliance requirements at the local level addresses commenters’ concern that the rule be 

implemented in a way that will maximize net benefits to society – both overall and locally. For 

details, see Essay 22. 

Essay 37 330 
Essay 38: Impact on Rural Electric Cooperatives

Multiple commenters argue that this regulation would adversely affect rural cooperatives in a 

disproportionate manner. Commenters’ arguments include: 

	 Because electric cooperatives are not-for-profit, they would have to pass all compliance 

costs directly onto consumer-owners. 

	 Electric cooperatives, being rural, have “fewer consumers” to which they may pass 

compliance costs, leading to disproportionately higher impacts on electric cooperatives 

and their customers. 

	 Businesses that are cooperatives’ electricity consumers will lose competitiveness due to 

higher electricity prices. 

	 Communities with already stressed budgets for schools and other public services will be 

adversely affected as they enact budget cuts in response to increased rates. 

	 Rural cooperatives may close due to regulatory requirements, leading to job losses. 

EPA does not agree with the commenters’ arguments on several grounds. 

	 EPA notes that the commenters provided no substantive information to support their 

claim that electric cooperatives, as an ownership category, would incur impacts that are 

disproportionately greater than that of other ownership categories. The arguments are all 

qualitative and conjectural with respect to how electric cooperatives and their customers 

might be disproportionately affected by the final rule. Commenters argue that the 

business profile of electric cooperatives in terms of a requirement to pass through 

compliance costs in electricity rates is somehow different from other categories of 

ownership in terms of potential for adverse impact. EPA does not agree with this claim. 

Much of the generating capacity estimated subject to the final rule (61 percent) continues 

to operate in States with rate-regulated electricity generation markets where costs are 

passed forward in rate increases to electricity customers. Customers of electric 

cooperatives will experience similar rate effects to those experienced by the customers of 

regulated utilities and municipally owned generators that incur costs from the final rule: 

both of these categories of generators will pass forward essentially all compliance costs 

to their customers. EPA also notes that estimated rate effects are uniformly quite low by 

electric power market region. 

	 Commenters argue that electric cooperatives have “fewer” customers and that this profile 

again will somehow lead to a disproportionate adverse impact from the final rule. EPA 

notes that the scale of compliance technology requirements and associated costs increase 

in an approximately proportional manner to the size of affected generating facilities and 

presumably the customer base that they serve. As a result, just because electric 

cooperatives have a smaller generation and customer base does not mean that their 

customers will incur disproportionately higher rate effects. Some commenters pointed out 

that electric cooperatives have very low customer density on an area basis, and that this 

Essay 38 331 
operating profile would somehow lead to disproportionately higher rate effects. This 

argument might have validity if the final rule applied requirements to electric power 

distribution systems. However, the rule applies only to the cooling water intake systems 

of the generating facilities; customer density on an area basis will have no effect on the 

costs incurred by those customers. 

	 Finally, EPA’s analysis finds that electric cooperatives, like parent entities of regulated 

facilities in other ownership categories, will generally incur low costs relative to their 

baseline revenue. In addition, EPA’s analysis also finds that cooperatives will not be 

disproportionately affected in terms of compliance costs compared to parent entities of 

regulated facilities in other ownership categories. As reported in Chapter 4 of the 

Economic Analysis of the Final Section 316(b) Existing Facilities Rule (EA) report, EPA 

used a cost to revenue analysis at the level of the parent entity to assess potential cost 

impacts on owners of electric power facilities that are subject to the final rule. From this 

analysis, EPA estimates that all electric cooperatives that own regulated facilities will 

incur costs of less than 1 percent of revenue under the final rule. This finding is almost 

identical to the finding for all other ownership categories, with majority of owners of 

regulated facilities incurring costs of less than 1 percent of revenue under the final rule. 

Based on this analysis, EPA does not agree that electric cooperatives, as an ownership 

category, will incur costs that are systematically higher than those of other ownership 

categories. 

	 Some commenters raised the possibility that electric cooperatives that own regulated 

facilities might close because of the final rule. EPA notes that its analysis of the impact of 

the final rule on generating capacity conducted using the Integrated Planning Model 

(IPM) found very limited closure effects, with only 23 of the 14,920 generating units 

modeled in IPM closing under the final rule, which accounts for only 0.1 percent of total 

national capacity. The vast majority of these generating units are at facilities not owned 

by cooperatives. 

	 Given these overall findings, EPA does not agree that commenters’ other arguments 

concerning, for example, impact of public budgets and public services, are valid in terms 

of disproportionate adverse impacts. 

Essay 38 332 
Essay 39: Reliability and Electricity Rate Impacts

Overview of Comments

Commenters expressed concern over the potential effects of the regulation on generating 

capacity and electric supply reliability, and on electricity rates at the national and State levels. 

The comments include: 

	 Commenters pointed to potential premature plant retirements, resulting from the large 

expenditures otherwise required to comply with the Section 316(b) Existing Facilities 

Rule, leading to capacity shortfalls, decreased electricity supply and reliability issues. In 

turn, these effects would lead to higher electricity rates for consumers. 

	 Some commenters specifically pointed out that the cost of installing cooling towers 

would be too burdensome for some facilities forcing them to retire. Other commenters, to 

support their reliability and electricity rates concerns, cited studies published by the 

North American Electric Reliability Corporation (NERC) and Electric Power Research 

Institute (EPRI). 

	 Some commenters stated that it is unrealistic to assume that this rule would not result in 

any closures, given that one facility they used as an example is likely to shut down. 

	 Some commenters pointed out that the electric generating facilities subject to the final 

rule are base-load steam electric generating units, which are essential to meeting 

electricity demand, maintaining adequate reserve margins, and providing electricity at 

affordable rates. These commenters pointed out that making sure that these units are not 

adversely affected is essential to meeting ever growing electricity demand as the 

economy recovers from recession. 

Riverkeeper, on the other hand, argued that even the most stringent option analyzed in support of 

the Proposed Section 316(b) Existing Facilities Rule – Option 3, which would require closedcycle retrofit for all facilities – would not have adverse reliability effects or result in large 

electricity rate increases at the national or NERC region level. Even the small estimated capacity 

retirements, Riverkeeper argued, are likely to be overestimated. Further, Riverkeeper added that, 

potential reliability effects, if any, under this option, can be mitigated by new energy efficiency, 

demand side measures, and usage of renewable resources. The absence of plausible electric 

reliability concerns associated with Option 3, Riverkeeper argued, is another reason that EPA 

should select Option 3 when promulgating the Section 316(b) Existing Facilities Rule. 

Riverkeeper specifically challenged assumptions used in two studies that assessed the reliability 

effects of a closed-loop cooling tower requirement under the 316(b) regulation – (1) the NERC 

2010 Special Reliability Scenario Assessment; Resource Adequacy Impacts of Potential U.S. 

Environmental Regulations and (2) the 2011 Review of the Potential Impacts of Proposed 

Environmental Regulations on the ERCOT System – and argued that because of these 

assumptions, the impacts estimated in these studies are overstated. 

	 Riverkeeper argued that the assumption of no cost-pass-through EPA made in the cost-torevenue analysis conducted at the facility and entity level and the assumption of 100 

Essay 39 333 
percent cost pass through EPA made in the electricity rate and household impact analyses 

are overly conservative and unrealistic. 

	 Florida Public Service Commission (FPSC) expressed concerns regarding the impact the 

section 316(b) regulation will have on electricity rates and consequently, Florida 

residents and economy. FPSC also presented results of its own electricity rates analysis. 

	 One commenter suggested that the final rule should encourage the operation of units with 

the lowest cost and lowest emissions in order to minimize the increase in electricity rates. 

	 Some commenters noted that because there is only a short period is which regulated 

facilities are expected to install compliance technologies to meet impingement mortality 

limits, all these facilities, which make up nearly 50 percent of all electricity power 

facilities in the industry, will be competing for scarce resources during the same time. 

	 Some commenters argued that because of the dynamics of deregulated wholesale 

markets, facility closures in those markets will result in higher profits to facilities that 

will not need to do anything to comply with the 316(b) regulation, and in higher 

electricity prices to consumers even when there are no environmental improvements in 

the areas they live in. These “unproductive” costs, these commenters argued, “represent a 

diversion of funds that would be better spent on environmental improvements or on 

reducing costs to already overburdened consumers.” 

	 EPRI expressed concern that EPA did not assess the impact of changes in electricity rates 

due to regulation on low income consumers as part of the environmental justice (EJ) 

analysis. 

Still, other commenters urged EPA to consider alternative compliance standards for loadfollowing and peaking generating units. 

	 “...several urban areas were identified where the existing transmission system would not 

be able to transfer sufficient electricity during periods of extended downtime.” (EPA 

2011a, p. 22208) 

	 “While BLE is not located in an urban area, it does serve an area that has been 

transmission-constrained. EPA found that, in some areas, even though excess capacity 

could be generated by other plants within the area, it may not be enough to replace the 

capacity lost during the extended downtime.” (EPA 2011a). 

General Concerns Regarding Reliability and Electricity Rate Impact

EPA acknowledges commenters’ concerns regarding the potential impact of the 316(b) 

regulation on reliability and electricity rates. However, as documented in the economic analysis 

for the final rule, EPA’s analyses found no material adverse effect on reliability and electricity 

rates from the final rule. Accordingly, EPA does not agree with commenters’ claims of adverse 

impact. Moreover, EPA notes that most of these commenters did not provide specific 

information to substantiate these concerns – in particular, as the concerns relate to the 316(b) 

existing facilities rule. Some commenters cited the fraction of electric power generating capacity 

subject to the 316(b) regulation as a sign of potential reliability issues and large electricity price 

increases. However, EPA does not agree that the fraction of generating capacity subject to 

Essay 39 334 
regulatory requirements, by itself, is a meaningful indicator of reliability issues, or of large 

increases in electricity rates. 

First, under the final rule, specific regulatory requirements, and associated compliance costs, will 

vary by facility and depend on baseline characteristics of a given facility; some facilities will not 

have to install any compliance technology. For those facilities that install compliance 

technology, the impingement control performance that is specified by the rule is considerably 

less expensive, and results in considerably smaller energy effects, than entrainment control 

technology (cooling tower), the technology standard on which a number of the commenters 

based their concerns. In particular, the NERC, EPRI and ERCOT studies that were referenced in 

some of these comments all assume a requirement for installation of closed-cycle recirculating 

systems, which is not established as Best Technology Available under the final rule. In addition, 

the final rule establishes a structure, information requirements, decision criteria, schedule and an 

overall process for assessing entrainment on a site-specific basis that will serve to guide 

permittees and permitting authorities in implementing the rule requirements. To the extent that 

facilities believe non-water quality impacts such as reliability (including localized transmission 

concerns), etc. should be considered in the site-specific determinations, the final rule provides for 

the opportunity for facilities to provide such information and for the Director to consider it, as 

appropriate. 

Second, the magnitude of electricity rate effects will vary by region and depend on the cost of 

compliance technology, the fraction of capacity affected by the regulation, and the extent to 

which regulated facilities in that region will be able to pass their compliance costs through to 

consumers. Whether and to what extent regulated facilities are able to pass their compliance 

costs to consumers will also affect the magnitude of financial impact on those facilities. As 

discussed in Chapters 4 and 6 of the Economic Analysis for Section 316(b) Exiting Facilities 

Rule (EA) report, EPA found no indication that the final rule will have substantial adverse 

financial effects on either regulated facilities or their parent entities, result in adverse reliability 

impacts, or lead to significantly higher electricity rates. While EPA did not conduct its cost and 

economic impact analyses at the level of the individual State, the Agency did perform analyses 

by NERC region, which is a more appropriate market concept than individual states for 

understanding potential reliability and electricity rate effects. None of the analyses, whether at 

the national level or by NERC region, found a substantial adverse effect on reliability or rates. 

Concerning a potential impact of the existing facilities rule to not use the lowest production cost 

and lowest emission generating units, the rule does nothing to interfere with dispatching the 

lowest production cost units to meet electricity demand. Regional power pools and system 

operators are expected to continue use of economic dispatch. Given the finding of small effect on 

electric supply reliability and electricity rates, EPA further concludes that the final rule does not 

alter production costs and dispatch patterns in a way that leads to higher electricity rates. 

Potential Capacity Closures Due to the Final Rule

Some commenters argued that EPA estimated no capacity closures at proposal for the existing 

facilities rule and disagreed with this finding. In fact, EPA did estimate and report capacity 

retirements as part of the cost and economic impact analysis for the proposed and final rules. As 

discussed in Chapter 6 of the EA report for the final rule, EPA found that the final rule will result 

Essay 39 335 
in some capacity closures. However, the capacity retirements estimated for the final rule 

represent very small shares of total generating capacity in the United States (e.g., 0.1 percent of 

total generating capacity in 2030 for the analysis of the final rule) and would not result in 

adverse reliability effects. Further, the small capacity retirements are likely to be easily replaced 

by new capacity. 

Given the finding of minimal expected capacity closures across the regulated industry due to the 

final rule, EPA also found the concerns regarding base-load units are not likely to be realized. 

Argument that Capacity Closures and Related Reliability and Rate Effects under an

All‐Cooling Tower Regulation Would be Acceptable

Riverkeeper stated that capacity retirements estimated for each of the regulatory options 

analyzed in support of the Proposed Section 316(b) Existing Facilities Rule are not nearly 

enough to cause reliability concerns, given the very small absolute amount and share of total 

generating capacity they represent. Further, Riverkeeper stated that the outlined compliance 

schedule provides enough lead time to construct capacity required to replace any capacity retired 

under Option 3 (all cooling tower). Riverkeeper further argued that even these small effects are 

likely overstated because the Integrated Planning Model (IPM) platform EPA used for the 

market model analysis conducted for the proposed rule – IPM V3.02_EISA – reflects out-of-date 

demand forecasts (from Department of Energy’s Annual Energy Outlook for 2008), which are 

higher than current demand forecasts. According to Riverkeeper, in DOE’s more current 

projections – AEO2011 – electricity demand in 2030 is more than 12 percent below that 

projected in AEO2008. Therefore, Riverkeeper claimed, less retired capacity would need to be 

replaced by new cleaner capacity, thereby reducing the overall cost of analyzed options and 

reliability concerns. 

Riverkeeper also cites IPM analyses that it undertook using a more recent IPM platform – IPM 

V4.10 – which also showed small adverse capacity effects from an all-cooling towers regulatory 

option. 

EPA acknowledges Riverkeeper’s arguments concerning the IPM platform and capacity impact 

findings from proposal. For its market model analysis of the final rule, EPA used a more current 

IPM platform – IPM V4.10_MATS – which reflects more current electricity demand forecast 

and includes costs associated with Final Mercury and Air Toxics Standards (MATS) and CrossState Air Pollution Rule (CSAPR). This platform is also more current than the IPM V4.10 

platform that Riverkeeper used in its own analyses. As discussed in Chapter 6 of the EA report, 

EPA found minimal capacity effects from this analysis. 

EPA notes that while it considered closures, reliability, and rate effects in evaluating regulatory 

options for the final rule, none were dispositive. See section VI of the final preamble. 

Argument that Adverse Capacity Effects are Overstated because of Overly

Conservative Assumptions in the IPM Analysis

Riverkeeper noted that retirements are likely overstated in the IPM analysis because EPA 

assumed that none of the rule’s compliance costs would be passed to consumers, which 

Riverkeeper argues is an overly conservative assumption, and leads to overstatement of adverse 

Essay 39 336 
effects. In response, EPA notes that Riverkeeper’s understanding of the IPM analysis is not 

entirely correct in that to the extent that IPM models purely competitive wholesale markets, it 

allows for some pass-through of compliance costs. As a result, some regulated facilities may be 

able to recover some of their compliance costs in the context of IPM analysis. To the extent that 

some facilities actually operate under a cost of service rate regulation framework, they will likely 

be able to pass nearly all of their compliance costs through higher electricity rates. As a result, 

regulatory impacts as modeled in IPM may be overestimated. Regardless, as described above, 

EPA found minimal adverse capacity impact for the existing facilities rule – in both the analyses 

at proposal and for the final rule. 

As noted above, EPA notes that while it considered closures, reliability, and rate effects in 

evaluating regulatory options for the final rule, none were dispositive. See section VI of the final 

preamble. 

Argument that Overly Conservative Consumptions Regarding Cost Pass‐Through

Lead to Overstatement of Impacts on Consumers and Overstatement of Impacts on

Regulated Facilities

Riverkeeper argued that the assumption of no cost pass through EPA made in the cost-to-revenue 

analysis conducted at the facility and entity level, and the counter-case assumption of 100 

percent cost pass-through for the electricity rate and household impact analyses, are overly 

conservative and overstate impacts in either direction. EPA acknowledges Riverkeeper’s 

concerns that these assumptions are conservative and likely to overstate impacts. However, EPA 

made these assumptions to avoid understating the potential impact of the existing facilities rule 

in either direction of effect – that is, for either the potential impact on regulated facilities that 

would incur compliance cost impacts at the outset, or for the impact on electricity consumers 

who would bear any rate increases resulting from the regulation. Given the analytic challenges 

and uncertainty in accurately assessing the cost incidence of the rule, EPA judges these 

assumptions as reasonable and appropriate for assessing the rule’s potential impacts on affected 

parties (see Chapter 3 of the EA document for further discussion of these considerations). 

EPA notes that while it considered impacts to the regulated facilities and their parent entities as 

well as electricity consumers in evaluating regulatory options for the final rule, neither were 

dispositive. See section VI of the final rule preamble. 

Overall Argument Favoring an All Cooling Tower Regulation

Overall, Riverkeeper argues that findings of low adverse impact on capacity, electric supply 

reliability, and electricity rates provide a basis for EPA to adopt closed-cycle recirculating 

system technology as the technology basis of the final rule (Best Technology Available or BTA). 

EPA acknowledges Riverkeeper’s statements and presentation of findings from EPA’s analyses. 

However, as described in the Federal Register notice for the final rule, and as documented in the 

TDD and EA reports, EPA based its determinations for the 316(b) existing facilities rule on a 

range of factors. While EPA considered non-water quality and other impacts described above in 

evaluating all of the regulatory options for the final rule, they were not dispositive. As explained 

in section VI of the preamble, three factors collectively support rejecting closed-cycle cooling 

Essay 39 337 
systems as a uniformly applicable BTA for existing facilities (except new units). These are land 

availability, increased air emissions and remaining useful life. Also, see Essay 10. 

Potential Impact of Rule on Electricity Consumers

EPA acknowledges FPSC’s concern regarding the potential impact of the existing facilities rule 

on Florida residents. EPA notes that while FPSC presented results of its electricity rates 

assessment, it did not provide enough information to validate these results. Further, FPSC 

estimated an average increase in a monthly residential bill per $100 million in environmental 

compliance costs. As shown in Table 4-6 of the EA report, EPA estimates that FRCC, which 

covers the vast majority of Florida (the entire area east of the Apalachicola River; areas west of 

the Apalachicola River are within the SERC Region), will incur approximately $32 million in 

compliance costs under the final rule or $0.14 per MWh of electricity sales. As shown in Table 

4-8 of the EA, this cost results in an average annual household bill increase of $1.91 or an 

average household monthly bill increase of $0.16. Using FPSC’s assumption that a typical 

residential Florida consumer uses 1.2 MWh of electricity per month, the average increase in a 

monthly household bill would be $0.17. EPA judges that this small increase in an average 

monthly bill is reasonable in relation to the Clean Water Act mandated environmental protection 

achieved by this regulation. 

Argument that Limited Timeframe for Regulatory Compliance May Lead to

Difficulties in Facilities Achieving Compliance with the Rule, with Associated

Reliability and Rate Impacts

Commenters express concerns that the large number of facilities subject to the Section 316(b) 

Existing Facilities Rule and the limited number of years for facilities to meet the rule’s 

impingement mortality limits could lead to challenges in facilities obtaining the capital, 

materials, and/or labor needed to install compliance technology. As a result, inability to achieve 

compliance would adversely affect supply reliability and rates if facilities are not able to generate 

electricity. EPA acknowledges these concerns; however, EPA does not agree with the 

commenters. 

To address concerns about the compliance schedule in the proposed rule, EPA revised the 

compliance requirements in the final rule so that the Director is required first to establish 

entrainment requirements in the final permit. The facility will then be required to comply with 

the impingement mortality standard as soon as practicable thereafter. In addition, because an 

entrainment requirement could require controls that take many years to design, finance and 

construct, the Director may establish interim milestones related to meeting the final requirements 

to ensure that the facility is making progress. These changes in the compliance timeline in the 

final rule, including the flexibility provided to Permit Directors to adjust compliance schedules 

and permit application requirements based on local considerations, should further reduce any 

compliance scheduling difficulties or inefficiencies facilities may have anticipated under the 

proposed rule. See section VIII on implementation in the preamble for more detailed discussion. 

Finally, in addition, discussed in the EA, the incremental resource requirements of the final rule 

are relatively small. 

Essay 39 338 
Undesirable Transfers of Income from Consumers to Electricity Generators

Commenters argue that some electricity generators may receive higher rates and profits in 

deregulated wholesale electricity markets, even if they do not install compliance technology as a 

result of the regulation. EPA acknowledges the commenters’ argument. However, EPA notes 

that once the Agency promulgates a regulation in a deregulated market, the Agency does not 

control which facilities will close, which facilities will incur additional compliance costs, and 

which will be deemed to already be in compliance because of technologies or practices they have 

already installed or undertaken. That is the nature of a deregulated market. Therefore, in a 

deregulated electricity market, it is possible that electricity prices may increase in certain 

locations as a result of the rule, but on average nationally, EPA estimates an average increase of 

$1.03 per household as a result of the final rule. 

Assertion that EPA Assess the Potential Impact of Electricity Rate Increases on Low

Income Consumers

EPRI argued that EPA should account for the potential impact of regulation-induced increases in 

electricity rates on low income consumers in the context of the environmental justice (EJ) 

analysis for the regulation. EPA acknowledges EPRI’s concern. However, EPA met the 

requirements for EJ analysis in accordance with Executive Order 12898 on Environmental 

Justice. Moreover, as discussed in the EBA report for the proposed rule and EA report for the 

final rule, EPA assessed the impact of electricity price effects based on ‘typical household’ 

electricity consumption levels independent of household income level, and did not find a 

substantial impact. 

EPA Should Consider Alternative Compliance Standards for Load‐Following and

Peaking Generating Units

EPA has addressed the issue of using capacity utilization rates as a basis for alternative 

compliance standards in Essay 19. See that essay for a detailed discussion. 

Essay 39 339 
Essay 45: Market Model Analysis Conducted Using IPM

The Electric Power Research Institute (EPRI) and Riverkeeper commented on various aspects of 

EPA’s electricity market model analysis using the Integrated Planning Model (IPM). 

Commenters’ arguments include: 

	 Some results appear contradictory and/or counterintuitive: EPRI argued that some of 

the results of EPA’s market model analysis using IPM appear contradictory, and stated 

that EPA should better defend or explain these counterintuitive results: 

o	 Electricity prices decrease in several North American Electric Reliability 

Corporate (NERC) regions despite the cost of regulatory requirements analyzed 

for the proposed rule. EPRI found it especially counterintuitive because these 

same NERC regions are projected to have less retired capacity under regulatory 

options. 

o	 Some generating units avoid closure in the analysis – i.e., units closing in the 

baseline scenario but remaining open in the policy scenario – despite electricity 

price decreases. 

EPRI does not explicitly state that these concerns refer to results reported for the steady-state 

analysis year of 2028; however, the analysis results to which EPRI referred are for that year. 

Further, the concept of capacity retirement is relevant only in the context of the steady-state 

analysis. 

	 Use of an older IPM platform and potential overstatement of rule impacts: 

Riverkeeper expressed concern that EPA’s market model analysis for the proposed rule is 

based on an older platform – IPM V3.02_EISA – which (1) does not reflect newer air 

regulations (most notably, the final Cross-State Air Pollution Rule (CSAPR) and Mercury 

Air Toxics Standards (MATS)), (2) incorporates an older, pre-recession electricity 

demand forecast, and (3) does not incorporate the most current universe of electric 

generating units. As a result, Riverkeeper argues that EPA’s proposal analysis was not as 

“accurate as it could have been,” and, more specifically, overstated the potential impacts 

of the existing facilities rule options, in particular, the previous Option 3 (“all cooling 

towers”). 

Following publication of the proposed rule analyses, Riverkeeper commissioned its own 

analysis of the 316(b) “all cooling towers” option, using a more current IPM platform – 

IPM V4.10 – which incorporates final CSAPR and MATS, a more recent electricity 

demand forecast, and an updated universe of generating units. In this analysis, 

Riverkeeper found lower capacity retirements for the “all cooling towers” option than 

EPA reported in its analysis at proposal. Riverkeeper argues that EPA should take these 

findings into account in deciding on the final rule. 

Essay 45 340 
EPA acknowledges the comments from both parties, and has responded directly to parts of these 

comments in its analyses and documentation for the final rule. Specific responses to EPRI’s and 

Riverkeeper’s comments concerning the IPM-based market model analysis follow below. 

Also, the EPA also would stress that its decision about what national standards for impingement 

and entrainment to promulgate took a variety of factors in addition to the impacts of different 

control options, into consideration. In deciding on its final regulatory option (and in rejecting 

others), projected impacts from IPM were not a dispositive factor. See section VI.E of the final 

preamble for additional discussion. 

Some Results Concerning Electricity Rates Appear Contradictory and/or

Counterintuitive

EPA understands EPRI’s comments that the IPM-based findings of lower electricity rates in 

some NERC regions for the 316(b) regulatory options may be counterintuitive, and has provided 

stronger explanation of these results in its documentation for the final rule. 

Responding more specifically to EPRI’s comment regarding decreasing electricity rates in 

certain regions, EPA emphasizes that the findings of potential increases or decreases in 

electricity rates are very small for all of the regulatory options analyzed in IPM, and in particular, 

for the final rule specification. EPA views these small changes – increase or decrease – as being 

well within the uncertainty range of the IPM analysis system. 

Responding specifically to EPRI’s comment regarding avoided capacity losses despite electricity 

rate decreases, EPA observed similarly small retirements of generating capacity for the 

regulatory options and by NERC region. EPA also notes, as did EPRI, that some capacity 

estimated as a baseline closure in IPM becomes an avoided closure under a given regulatory 

option. This finding would result from differences in compliance costs across generating units: 

some units that are closures in the baseline return to economic viability in the policy case 

because they would incur lower or no compliance costs due to some operating characteristic and 

consequently, will become less expensive to run, compared to other operating units that incur 

higher compliance costs. To address these counterintuitive findings, EPA has strengthened its 

discussion in the economic analysis report for the final rule. 

Regarding EPRI’s comments that EPA did not account for electricity rate effects in its 

environmental justice analysis, or in the employment impact analysis, EPA refers the commenter 

to EPA’s responses to comments on environmental justice (Essays 39 and 73) and employment 

effects (Essay 36). 

Use of an Older IPM Platform and Potential Overstatement of Rule Impacts

EPA acknowledges Riverkeeper’s observation that it used an IPM platform for the proposed rule 

analyses (IPM V3.02_EISA) that is not as current as platforms developed since that time. After 

the proposed rule analysis, EPA developed the IPM V4.10 platform, which was used in 

Riverkeeper’s analyses, and later the IPM V4.10_MATS platform. EPA also acknowledges that 

using a more current IPM platform might have shown different regulatory effects. As discussed 

in Chapter 6 of the Final Economic Analysis for the Final Section 316(b) Existing Facilities Rule 

(EA), EPA conducted a market model analysis of the final rule using the most current IPM 

Essay 45 341 
platform available at the time of analysis – IPM V4.10_MATS; this platform is updated from the 

IPM platform – IPM V4.10 – used for Riverkeeper’s analysis of Option 3. While the IPM V4.10 

embeds the Proposed Transport Rule and the Proposed Toxics Rule, the IPM V4.10_MATS 

platform embeds both Final CSAPR and MATS. The analysis using the more current platform 

continues to find very small rate and capacity effects. Given these findings, EPA continues to 

conclude that the rate and capacity effects of the final regulatory option are acceptable. 

Essay 45 342 
Essay 47: Economic Impacts on Manufacturers

Commenters claim that EPA’s assessment of economic impact on manufacturers fails to 

appropriately consider a number of adverse impacts. 

	 EPA did not account for the impact of increased electricity rates on manufacturers. 

	 Manufacturers face stiff competition from foreign producers who are not subject to the 

316(b) regulation. 

o	 EPA acknowledges no cost pass-through and that costs will be absorbed by 

facilities. 

o	 Reducing competitiveness of manufacturers will hurt balance of trade and 

domestic employment. 

o	 EPA concludes foreign trade (really export dependence) is not a significant factor 

because manufacturers sell only 17 percent of output abroad. 

	 Manufacturers also face costs from other regulations addressing air emissions from 

boilers and heaters. 

	 Manufacturers are uniquely affected because unlike regulated public utilities, they cannot 

recover costs; therefore, profit margins will be directly affected as will facility’s ability to 

hire and retain workers. 

	 Manufacturers are very important to both the local and national economies and a closure 

could have severe negative economic impacts on the local economy. 

Additionally, one commenter argued that EPA did not consider the cost or the economic impact 

for non-manufacturing facilities that may be affected by the rule if, in fact, the intent of the 

proposed rule was to regulate these facilities. 

A number of commenters argued that EPA did not adequately account for the impact of the 

existing facilities rule on manufacturers that face competition from foreign producers, whether in 

domestic markets or in export markets. Commenters argued specifically that EPA did not 

adequately account for the fact that foreign competitors would not face the rule’s compliance 

requirements and would therefore gain a competitive advantage over U.S. producers who are 

subject to the rule. Some commenters stated that EPA did consider the impact of foreign 

competition – for example, in assuming no pass-through of compliance costs – but did not go far 

enough in considering the impact of reduced competitiveness on balance of trade and domestic 

employment. In particular, one commenter argued that EPA did not consider export dependence 

to be a significant factor because on average, facilities sell only a certain percentage of their 

output abroad. In addition, some commenters argued that many manufacturers faced compliance 

costs from other regulations, which again will not affect their competitors abroad. 

Essay 47 343 
The EPA did account very specifically for the impact of compliance costs on the ability of 

regulated facilities to compete with other producers, both foreign and domestic, who do not face 

compliance requirements under the existing facilities rule in its assessment of the cost and 

economic impact on manufacturers. As acknowledged by commenters, EPA’s analysis of cost 

pass-through potential accounted for a range of factors – including export dependence and 

import penetration – in determining that facilities operating in any of the Primary Manufacturing 

Industries would not likely be able to recover compliance costs from their customers (for a 

complete discussion of the cost pass-through analysis, see Appendix K of the EA). Given this 

finding, EPA analyzed the impact of the regulation on manufacturers assuming that none of the 

regulated facilities would be able to raise prices to recover compliance costs and would have to 

absorb these costs in their baseline income and cash flow. While EPA’s analysis may reflect 

overall conditions due generally to competition within the affected industry segments that will 

not experience a regulation-induced cost increase, there are likely to be instances in which some 

regulated facilities will be able to recover some costs through price increases. Such instances 

may occur in niche markets – for example, based on specific product or regional segmentation – 

in which facilities would have flexibility to increase prices. Alternatively, some cost recovery 

could occur in specific product markets in which a substantial share of production would incur 

regulation-induced cost increases. To the extent that some manufacturers will be able to pass the 

increase in their costs due to the final rule onto consumers, the assumption that no facilities 

would be able to increase prices is conservative and likely to overstate impacts on regulated 

facilities. Nevertheless, even with this conservative assumption, EPA found no significant 

adverse impact of the final rule on the sample of surveyed facilities in its economic/financial 

analysis. EPA’s analysis found that no facilities would close as a result of the rule and that only 

three percent of facilities would encounter financial stress short of closure, i.e., adverse changes 

in a facility’s financial position that are not threatening to its short-term viability, but may 

present challenges in obtaining financing, as a result of the final rule (for details see Chapter 5 of 

the EA). 

With specific regard to the concerns about foreign competition, EPA assumed that facilities 

would not be able to recover compliance costs through increased prices. Given no changes in 

price, EPA concluded that there would be no change and certainly no negative effect on 

facilities’ competitive position in the global market or resulting effects on domestic employment 

and balance of trade. 

EPA recognizes that manufacturers must also comply with and will incur costs from other 

regulations. For this reason, EPA conducted a sensitivity analysis that accounted for the cost of 

other regulations that have been recently promulgated, and that could impose costs on regulated 

facilities. This analysis found that no facilities would incur severe impacts as a result of the 

combination of the final rule and other regulations (for details see Appendix N of the EA). 

With respect to the potential impact on facilities’ profit margins and related impact on their 

ability to hire and retain workers, as described in the EA document (Chapter 5), EPA performed 

financial analyses based on detailed income statement and baseline sheet information from an 

extensive sample of facilities. This analysis assessed the impact of compliance costs on facilities’ 

cash flow and measures of financial performance and condition. As stated above, in these 

analyses, EPA found that no facilities would close and that only 3 percent of facilities would 

encounter financial stress short of closure, i.e., adverse changes in a facility’s financial position 

Essay 47 344 
that are not threatening to its short-term viability, but may present challenges in obtaining 

financing, as a result of the final rule. 

Therefore, EPA does not expect material effects on facilities’ ability to hire and retain 

employees. Some commenters pointed to facility closure and associated employment losses as an 

outcome of the regulation. Again, as described above and documented in the EA report for the 

final rule, EPA’s analysis found no facility closures as a result of the final rule’s compliance 

requirements. 

Some commenters argued that the cost and economic impact analysis that EPA conducted is 

flawed because it did not account for the impact of increased electricity rates on manufacturers. 

Commenters contend that even a rate increase of one percent would have a major effect on 

manufacturers because of the large amount of electricity they purchase. As part of the impact 

analysis for regulated electric power facilities, EPA estimated potential rate impacts by customer 

class for each NERC region. This analysis assumed that regulated electric generating facilities 

would pass through all of their compliance costs under electricity rate regulation procedures, 

which may not be the case in all States, and thus may overstate the overall potential rate impact 

of compliance outlays on electricity consumers. For industrial customers, which would include 

regulated manufacturing facilities, EPA estimated an average national increase of 0.1 percent, 

with the highest impact, 0.2 percent, in the SERC NERC region. EPA concludes that these very 

small rate increases, which apply to only the electricity component of a manufacturing facility’s 

production inputs, will have a minimal impact on U.S. manufacturers, regardless of the amount 

of electricity they purchase. 

Finally, EPA disagrees with the assertion that it did not consider cost and economic impacts to 

non-manufacturing facilities, i.e., cooling water-dependent facilities that responded to the 316(b) 

industry survey whose principal operations lie in businesses other than the electric power 

industry or the Primary Manufacturing Industries. Throughout its cost and economic impact 

analyses, EPA refers to these additional industries as “Other Industries,” but refers to facilities in 

these industries under the broad terminology of manufacturers. In the analyses EPA conducted 

for manufacturers, EPA considered impacts to both facilities in the Primary Manufacturing 

Industries as well as facilities in the Other Industries. 

Essay 47 345 
Essay 48: Rule Should Establish Performance Metrics to Track and

Validate Public Policy Value of Rule’s Requirements

EPA has complied with the requirements of the Unfunded Mandates Reform Act. The statute 

requires federal agencies, unless otherwise prohibited by law, to assess the effects of their 

regulatory actions on State, local, and Tribal governments and the private sector. The preamble 

to the final rule explains EPA assessment of the effects of EPA action and how EPA developed 

the information used for its assessment. In doing so, EPA has followed its traditional approach, 

relying on EPA standard models for its evaluations. EPA did not develop any new tools for its 

assessment or new models to test the impact of its regulation going forward given existing 

resource constraints. Based on the historic performance of its analytical tools, EPA is confident 

that today’s assessment will appropriately reflect real word outcomes. 

Essay 48 346 
Essay 50: Alternative Compliance Responses

Riverkeeper claims that EPA overstated the costs of complying with any option because EPA did 

not consider energy efficiency, renewable energy, or repowering as alternatives. Riverkeeper 

points to the fact that compliance methods were inputs, as opposed to outputs, of the IPM 

modeling and therefore only options that directly met regulatory requirements were considered. 

Riverkeeper argues that repowering to combined cycle while converting to CT might provide a 

lower cost option than replacement with new generation, and indicates that this was not 

considered. Riverkeeper also highlights demand reduction through energy efficiency/demand 

response and replacing generation with renewable energy that doesn’t require cooling water, as 

two additional options that EPA failed to consider. Specifically, Riverkeeper points to the results 

of the energy efficiency sensitivity completed for the Utility MACT, which showed a major 

reduction in cost. 

EPA analyzed compliance responses to regulatory requirements based on detailed information 

for regulated facilities, including cooling water requirements, baseline cooling water intake 

systems, and other site and operating information that is important in determining the type, size 

and operating characteristics of equipment that would be needed to achieve compliance with the 

existing facilities rule. The technology needed to achieve compliance underlies, in turn, EPA’s 

estimates of capital and operating costs and other operating effects (e.g., downtime, auxiliary 

energy requirements, and energy penalty) at the level of the regulated facility. These costs and 

operating effects are also the basis for EPA’s estimates of the total social cost of the rule. 

EPA views this approach as an appropriate and credible basis for estimating the cost of the rule. 

In complying with the rule, facilities may implement designs and/or changes in facility 

operations that differ from those estimated by EPA, and that may result in lower costs to the 

facilities and to society. Different approaches could include, for example, conversion of existing 

generating capacity to natural gas/combined cycle or renewable energy-based generation, or use 

of demand management approaches to offset need for electric generating capacity as part of a 

comprehensive strategy for regulatory compliance, as suggested by the commenter. However, 

whether and how facilities would implement such approaches depends on assessments of facility 

circumstances, business objectives, and business planning. It is beyond EPA’s ability to try to 

account for such considerations in its analyses, given the information currently available. 

Accordingly, EPA acknowledges that facilities may choose less costly approaches than those 

embedded in its cost estimates for the final rule. In that case, the rule may prove less costly to 

society than EPA has estimated in its cost analysis. As a result, EPA’s determinations in support 

of the final rule would only be strengthened as the rule’s benefits would be achieved at lower 

cost to society. 

The EPA also would stress that its decision about what national standards for impingement and 

entrainment to promulgate took a variety of factors in addition to the cost of different control 

options, into consideration. In the case of EPA’s decision to adopt a prescribed national 

framework for determining entrainment controls on a site-specific basis as its best technology 

available (BTA) 316(b) standard, cost was not a direct factor in rejecting a single, national 

technology standard. The EPA did not reject closed-cycle cooling as the sole technology basis 

Essay 50 347 
for the national standard because of its costs. Rather, EPA concluded that land availability, air 

emissions and the remaining useful plant life supported a decision to rely on a case-by-case 

determination of entrainment controls in a nationally-prescribed process mandating the 

consideration of these and other factors. 

Essay 50 348 
Essay 53: Electricity Rate and Reliability Impact to be Considered During

Site‐Specific Evaluation

Utility Water Act Group (UWAG) recommended the site-specific determinations for permit 

decisions should not only consider benefit and cost information, but also assessments of (1) 

electricity rate impacts, by consumer group and (2) reliability concerns. UWAG stated that these 

assessments should be made using electricity models specific to a given electric power facility’s 

regional system. 

UWAG also requested that EPA remove the phrase “within the immediate area” so it could not 

be misinterpreted by permit Directors to mean that reliability impacts should only be assessed 

within the immediate surrounding area of a power plant. Instead, UWAG believes permit 

Directors should assess impacts on a local, state, and regional basis. 

The commenter argues that site-specific permit determinations should consider electricity rate 

effects and reliability concerns, in addition to more traditional benefit-cost considerations. EPA 

acknowledges the commenter’s recommendation and points out that the final rule provides that 

the Permit Director may consider a range of factors in determining best technology available 

(BTA) on a site-specific basis, which may include entrainment control technology. Section 

122.21(r)(12), Non-Water Quality Environmental and Other Impacts Assessment, of the 

preamble discusses the minimum information that facilities will have to submit, which includes a 

reliability assessment. The phrase “within the immediate area” no longer appears in the preamble 

at § 122.21(r)(12), Non-Water Quality Environmental and Other Impacts Assessment and EPA 

does not specify the geographic limits for this reliability assessment in the final rule. Instead, 

EPA gives latitude to Permit Directors to interpret reliability issues within an appropriately 

defined region. Permit Directors may account for such considerations as the market region in 

which generators operate, the extent of generation reserve margins at the time of installation 

downtime, and presence of any transmission constraints that could limit the ability of other 

generators to offset reductions in generating capacity due to the final rule. 

In addition, facilities can submit additional information for the Director’s review, which may 

include electricity rate assessment and any other information that facilities view as important to 

submit. Facilities can also submit this information as part of the comprehensive technical 

feasibility and cost evaluation study discussed in § 122.21(r)(10) of the preamble. 

Concerning the commenter’s recommendation that electricity market models specific to a given 

region should be used as the basis for information on electricity rates and reliability, EPA 

disagrees with the should element of this comment. If facilities decide that such assessments are 

appropriate for developing electricity rates and reliability information, then nothing in the final 

regulation precludes the facilities from using such models and submitting the information to the 

Permit Director. However, EPA does not agree that such methods for electricity rate and 

reliability should be a requirement or expectation for developing and submitting such 

information as part of permit submissions. 

Essay 53 349 
Essay 55: Facility‐Level Compliance Costs, Social Costs, and Costs to be

Submitted as Part of the Comprehensive Technical Feasibility and Cost

Evaluation Study

Many commenters asked EPA to clarify the relationship between facility-level compliance costs 

and social costs and specify the costs each of these concepts accounts for. Further, commenters 

asked EPA to be more specific on what cost information facilities have to submit to Permit 

Directors for review; some of these comments made suggestions about what information EPA 

may consider requiring. These comments include the following: 

	 EPA should explicitly state what the facility-level compliance costs and social costs 

include and how these two cost concepts are related. 

	 EPA should clarify what cost information must be considered by permitting authorities in 

evaluating the comprehensive technical feasibility and cost evaluation study required 

under the Existing Facilities Rule. Some of these commenters noted that while EPA did 

state that social costs, required for submission, should include outages, downtime, and 

other impacts to facility revenue, the Agency should be more specific regarding what 

these categories should include. 

	 EPA should provide Permit Directors with flexibility in identifying what social costs 

should include to account for regional differences in economic conditions. This 

suggestion is based on the assumption that because of regional differences, different 

regulatory impacts may constitute cost to society. 

	 EPA should explicitly state that social costs account for fogging, icing, salt drift, and 

visibility impacts, which are commonly recognized public welfare impacts of closedcycle cooling systems (Santee Cooper). 

	 The social costs estimated for the proposed rule (Proposal Option 1) include only costs 

associated with the impingement requirement and do not account for entrainment costs 

that will be required (Western Business Roundtable). 

	 EPA should include production losses associated with both manufacturing facility 

retirements as the result of the Proposed Section 316(b) Existing Facilities Rule and 

temporary facility shut downs required to install compliance technology, in social costs 

(American Chemistry Council (ACC)). ACC also expressed concern regarding high costs 

of manufacturing facility downtime, which EPA did not include in the social costs 

estimate. 

	 EPA should account for the social cost of grid reliability effects arising from electric 

power facility retirements and technology installation downtime (Utility Water Act 

Group (UWAG) and Edison Electric Institute (EEI)). UWAG and EEI further noted that 

Essay 55 350 
according to studies conducted by NERA and EPRI, these reliability effects are 

substantial. 

EPA clarified the relationship between facility-level compliance costs and social costs in the 

Economic Analysis for the Final Section 316(b) Existing Facilities Rule (EA) report by listing 

the specific cost components covered under each cost concept that EPA used in its assessment. 

The Agency also provided a more detailed explanation of differences in the methodologies used 

to estimate facility-level compliance costs and social costs. Further, EPA provided more detail 

on the cost information that facilities will submit as part of the technical feasibility and cost 

evaluation study in the preamble to the Final Rule and in the Information Collection Request for 

Cooling Water Intake Structures at Existing Facilities (Final Rule ICR). This information is 

available to guide facility representatives and Permit Directors in preparing and reviewing permit 

applications. Following promulgation of the rule, through outreach activities, EPA will consider 

the need for providing State Directors and facilities with any more detailed guidance on what 

cost information should be submitted for review and how certain cost may be calculated. 

The final rule accommodates commenters’ recommendation to provide Permit Directors with 

flexibility to account for regional differences in economic conditions in identifying and 

evaluating the specific social cost components as part of the technical feasibility and cost 

evaluation study. EPA notes that in discussing the permit application requirement at § 

122.21(r)(10) of the rule, the rule explains the minimum information that facilities will be 

required to submit as part of the technical feasibility and cost evaluation study. In addition, 

facilities may always submit additional information for the Director’s review. That information 

could include data on other cost components that facilities consider to be a cost to society and 

view as important for the Director to consider in the permitting decision. 

Regarding Santee Cooper’s recommendation to explicitly state that social costs of closed-cycle 

cooling systems account for fogging, icing, salt drift, and visibility impacts, the Agency 

understands that operation of closed-cycle cooling systems may indeed have these kinds of 

impacts depending on local circumstances. However, EPA notes that it did not adopt closedcycle cooling as the basis for the BTA entrainment standard for existing facilities under the final 

rule, and the ancillary effects that may be associated with installation of a closed-cycle 

recirculating cycle may not necessarily be associated with other entrainment reduction 

technologies. Some existing facilities may install closed-cycle cooling systems to meet 

entrainment reduction requirements established on a site-specific basis or to comply with the 

new unit provision of the final rule. However, EPA cannot predict with confidence the outcome 

of the site-specific BTA entrainment standard-setting proceedings, and therefore, which facilities 

will undertake such installations. Consequently, the EPA did not specifically identify these as 

factors to be considered by the Director in site-specific determinations. The final rule, however, 

does not preclude any facility from including in its determination of social costs the elements 

identified above or other elements as reflecting social costs associated with closed-cycle cooling 

or another entrainment reduction technology. EPA notes that facilities can submit this 

information for the Director’s review as part of the comprehensive technical feasibility and cost 

evaluation study if facilities consider these impacts to be of concern in their area and view the 

information as important to submit. 

Essay 55 351 
The social costs of the final rule, which closely align with Option 1 as analyzed for the proposed 

rule, appropriately include only direct technology costs associated with the impingement 

requirement and do not account for possible entrainment control technology costs for facilities 

for which entrainment BTA requirements will be established on a site-specific basis. As 

discussed in the preamble and in Essays 14 and 37, EPA did not estimate costs for entrainment 

controls under the final rule because the final rule does not establish a nationally applicable BTA 

for entrainment, but rather a framework for determining BTA for entrainment on a site-specific 

basis. As such, EPA cannot reliably predict the outcome of the site-specific BTA entrainment 

determinations. EPA did, however, estimate the cost for requiring entrainment control measures, 

e.g., cooling towers, at all regulated facilities with 125 mgd or greater (Proposal Option 2), 

which account for 90 percent of actual flows. The total annualized cost for that option would be 

approximately $3.6 billion at the three percent discount rate, which is under 0.03 percent of GDP 

in 2012 (see Essay 37). 

For a response to comments regarding downtime for manufacturers to install technologies to 

comply with today’s final rule, see Essay 35. 

In terms of potential facility closures, as discussed in Chapter 5 of the EA report, EPA found that 

no regulated manufacturing facility will close because of the final rule. Therefore, the social cost 

of production lost due to facility retirements is zero. 

The EPA concluded that any social costs potentially associated with the reliability effects from 

temporary and permanent shut downs of electric power generating facilities would not be 

significant for the following reasons. First, the EPA notes that its estimate of social cost did 

include the cost of downtime to society, which is the increase in electricity production costs from 

generators needing to supply the electricity otherwise produced by units that have temporarily 

shut down to install compliance technologies. In addition, where EPA’s analysis found that 

capacity would be retired because of the rule, EPA assigned a social cost to this capacity loss 

based, again, on the differential cost of generating the replacement electricity from alternative 

generating capacity. However, as discussed in Chapters 4 and 6 of the EA report, EPA found that 

the final rule would not result in significant capacity losses either at the national level or at the 

level of the North American Electric Reliability Corporation (NERC) region. As a result, EPA 

concluded that the final rule would not result in adverse reliability effects. Finally, EPA would 

note that the cited NERA and EPRI studies assessed capacity and reliability impacts in the 

context of a requirement for closed-cycle cooling installation and operation, which is not a 

required compliance technology for existing units at existing facilities. 

Essay 55 352 
Essay 58: EPA’s Consultation and Stakeholder Outreach

Several commenters stated that EPA has failed to comply with Executive Order 13132 with 

regards to Federalism. Specifically, commenters claim that EPA did not adequately consult with 

state agencies in developing the rule. One commenter stated that the Executive Order promotes 

localized policymaking. Commenters also requested that EPA document its compliance with this 

Executive Order. 

Other commenters stated that this rule is important to them and can have far-reaching effects; as 

a result, these commenters encouraged EPA to maintain an open dialogue with stakeholders 

(e.g., industry, state regulators, etc.) throughout the rulemaking process. 

First, for the reasons explained in Section XI. D. of the preamble and in Chapter 12 of the EA, 

EPA determined this final rule does not have federalism implications. Therefore, EO 13132 does 

not apply to this final rule. 

Nevertheless, EPA has actively engaged the states in developing the final rule. As stated in the 

preamble, EPA has conducted significant consultation and stakeholder outreach activities during 

the development of the final rule. EPA also disagrees that it did not engage states “early in the 

process,” as states have been active participants in the 316(b) rulemaking process since 2000 

with the Phase I new facility rule. Many states have actively participated throughout the several 

phases of rulemaking. In particular, given that the final rule addresses facilities that had been 

previously regulated by the Phase II and Phase III rules, states have been provided with ample 

opportunity to participate in the process. 

In addition to collection and consideration of the states’ comments, EPA has also conducted 

outreach by staging symposia, periodic calls with states, and other activities where EPA sought 

the input from local, state and tribal governments. As noted in section XI (D)(1)(c) Summary of 

State, Local, and Tribal Government Input of the preamble, EPA has conducted several 

conference calls with the Association of Clean Water Administrators (ACWA), including 

numerous states; and small business representatives, including some local government officials. 

EPA also combined its efforts and collected input from state and local government entities 

during development of the proposed Effluent Limitations Guidelines and Standards for the Steam 

Electric Power Generating Point Source Category, to which many of the same facilities are 

subject, as today’s final rule; see 78 FR 34530 (June 7, 2013) for more information. State and 

local officials attended numerous site visits with EPA’s staff, enabling EPA to gather their input; 

see DCNs 10-6510, 10-6518, 10-6520, 10-6521, 10-6523 and 10-6524. EPA also responded to 

requests for information from multiple state and local governments. In addition, EPA attended 

conferences and participated in workgroups (such as NARUC’s 2013 Winter Committee 

Meetings) where additional information about state and local government interests was 

presented. 

EPA also disagrees that it has not considered input from facilities that are owned by state and 

local governmental entities. As noted above, these facilities have participated in the rulemaking 

process for some time, including comments submitted by the commenter itself under the Phase I, 

Essay 58 353 
II, and III rules. Government-owned generators have submitted comments throughout the 

process as well; see, for example, comments from the City of Orrville Department of Public 

Utilities in the Phase I rule and the Lansing Board of Power and Light in the Phase II rule. EPA 

also conducted site visits to two municipally-owned electric generators; see DCNs 10-6523 and 

10-6524. 

EPA also notes that the final rule embodies the principles of the Executive Order by delegating 

significant decision-making to the Director, who in many instances is the State permitting 

authority. For example, entrainment requirements are determined entirely on a site-specific basis 

by the state permitting authority; this is in complete agreement with section 3(d) of EO 13132. 

For impingement requirements, as noted in the preamble, EPA is promulgating a national 

performance standard, but has provided multiple compliance alternatives, in effect allowing state 

and local entities to determine the best path to comply. 

Essay 58 354 
Essay 59: Executive Orders 12866: Regulatory Planning and Review and

13563: Improving Regulation and Regulatory Review

Many commenters stated that EPA failed to comply with Executive Orders (EOs) 12866: 

Regulatory Planning and Review and 13563: Improving Regulation and Regulatory Review. 

These comments include the following: 

	 One commenter stated that EPA violated EO 13563 by failing to present the time profile 

of social costs for Option 4 analyzed in support of Proposed Section 316(b) Existing 

Facilities Rule. 

	 Some commenters stated that EPA failed to quantify the effect on employment and job 

creation required under the Executive Order 13563: Improving Regulation and 

Regulatory Review. Some of these commenters conducted their own analysis of 

employment effects and presented analysis results as part of their comments. Further, the 

United States Chamber of Commerce noted that in order to produce a better informed 

regulatory result and provide the public with sufficient information to comment 

effectively, the employment impact analysis, among other things, must account for 

construction effects of modifying existing facilities, increased electricity rates, early 

facility retirements, and regional changes in employment distribution. 

	 Some commenters stated that EPA failed to explain how benefits justify costs, as required 

under EO 13563, given that costs significantly exceed benefits under all options analyzed 

in support of the Proposed Section 316(b) Existing Facilities Rule. 

	 Eastman Chemical urged EPA to carefully consider the need for and the cost of the 

Section 316(b) Existing Facilities Rule given that the U.S. economy is barely recovering 

from the biggest economic downturn since the Great Depression, which is what the 

President tried to encourage policymakers to do by issuing EO 13563. 

	 Electric Power Research Institute (EPRI) noted that out of 12 requirements of the 

Executive Order 12866, EPA addressed only one – the benefit-cost comparisons. Some 

commenters stated that EPA must publish a complete EO 13653 review addressing all 

issues addressed by that EO, including, aside from employment effects (discussed above), 

efficacy metrics (i.e., metrics that the Agency and the public may use to judge and 

determine the CWIS Rule’s burden and effectiveness), economic development, and 

information on quality certification. Regarding quality certification, the U.S. Chamber of 

Commerce specifically stated that EPA should have “evaluated, addressed and disclosed 

to the public a comprehensive Information Quality Act (“IQA”) analysis as part of its EO 

13563 review.” Unless EPA corroborates the quality of its information, the United States 

Chamber of Commerce continued, “the sufficiency of its science and statistics, and hence 

the integrity of its regulatory choices, are in doubt.” 

	 Some commenters stated that EPA failed to comply with EO 13563 because the Agency 

did not assess the cumulative impact of all recently proposed and currently pending 

Essay 59 355 
regulations affecting the electric power industry. Some of these commenters urged EPA 

to conduct cumulative costs and benefits analysis of these regulations, including 

assessment of reliability effects, required under EO 13563. Midwest Generation, Edison 

Mission Energy, LLC (EME) urged EPA to keep all goals of the EO 13563 in mind when 

developing the Final Section 316(b) Existing Facilities Rule, including “coordination, 

simplification, and harmonization.” 

	 Alcoa pointed out that the Section 316(b) Existing Facilities Rule is too prescriptive and 

instead of setting performance objectives, as required under the EO 13563, it sets out 

specific ways to comply with the rule. Further, Alcoa continued, the rule sets 

inappropriate standards given that the compliance responses required by the rule were 

developed based on the information on electric power facilities but also apply to 

manufacturers. 

EPA complied with Executive Order 12866 and 13563. See section XI.A of the final preamble 

and associated analysis in Chapter 12 of the EA. 

EPA also complied with requirements in the Data Quality Act and EPA’s Information Quality 

Guidelines. For example, EPA performed its analysis supporting this rulemaking within EPA’s 

data quality system. The commenter is incorrect that EPA must develop a comprehensive 

analysis that describes EPA’s data quality. EPA discusses this throughout the documents 

supporting the rulemaking. Further, the data and analysis underlying this rulemaking have 

undergone multiple levels of review including many opportunities for public comment and 

interagency review. Finally, where commenters have provided corrections to the data, as 

appropriate, EPA updated it. 

Comments on the Relationship between Social Cost and Benefits and EPA’s Selection

of and Support for the Proposed Rule

EPA acknowledges commenters’ input concerning the relationship between social cost and 

benefits. The Agency has carefully considered both the costs of and the need for the section 

316(b) Existing Facilities Rule. EPA judges that the compliance costs and resulting cost and 

economic impacts estimated for the final rule and detailed in the EA report are reasonable in 

relation to the Clean Water Act-requirement to implement section 316(b). 

Failure to Provide Time Profile of Social Costs and Benefits

EPA disagrees with commenter’s statement that the Agency did not present a time profile of 

social costs and benefits of Option 4. The Agency presented that information in Chapter 13 of 

the Economic and Benefits Analysis for the Proposed Section 316(b) Existing Facilities Rule 

(EBA) report. EPA also presented the updated time profiles of social costs and benefits for all 

three analyzed options in Chapter 8 of the Final Economic Analysis for the Final Section 316(b) 

Existing Facilities Rule (EA) report. 

Failure to Explain How Benefits Justify Costs

EPA disagrees with commenter’s statements that the Agency did not explain how the benefits of 

this rule justify its costs. See section V.H in the final preamble. Also see section X of the final 

Essay 59 356 
                                                            

preamble for a detailed discussion of the benefits analysis and section IX for a discussion of the 

cost and economic impact analysis. 

Failure to Quantify the Effect on Employment

EPA disagrees with commenter’s statements that the Agency did not quantify the effect of the 

proposed rule on employment and job creation as required under Executive Order 13563: 

Improving Regulation and Regulatory Review. For proposal, EPA presented quantitative 

analysis of employment effects in Chapter 10 of the Economic and Benefits Analysis for the 

Proposed Section 316(b) Existing Facilities Rule (EBA) report. 

For the final rule, EPA approached its analysis of employment effects differently than for the 

proposed rule. Specifically, unlike for the proposed rule, for the final rule, EPA did not estimate 

quantitative employment impacts but instead included only a qualitative discussion. In 

considering an approach for the final rule, the Agency concluded that the methods used at 

proposal were not sufficiently robust, largely because they relied on an input-output analysis that 

assumed fixed production relationships and used historical data to estimate the labor and other 

inputs required for compliance with the rule. Since publication of the proposed rule, EPA has 

concluded that the input-output analysis-based approach is inappropriate for assessing the 

employment impacts of national-level regulations. Input-output models are static, do not include 

prices, and assume the supply of all inputs is inexhaustible. They do not model a wide variety of 

adjustments that are expected to occur over time, such as changes in production processes, 

technology or trade patterns.58 

After reviewing the public comments EPA received on the proposed rule, the Agency concludes 

that the commenters have not identified any specific improvements to the employment analysis 

of the proposed rule. EPA acknowledges some commenters’ submissions of an employment 

effects analysis. However, because the commenters did not describe the methodology they used 

to generate these estimates, EPA was not able to compare the approaches and assess whether any 

changes to the analysis the Agency conducted were warranted. 

The final rule EA includes a qualitative discussion describing potential adjustments in the labor 

market that may follow the rulemaking. For the final rule, EPA sought methods that would 

circumvent the shortcomings of the methodology used for the proposed rule. However, as 

discussed in Chapter 9 of the EA report, because of the complexity of factors through which an 

environmental regulation may affect employment, the myriad uncertainties in assessing a 

regulation’s economy-wide, long-term employment effects, EPA conducted only a qualitative 

assessment of employment effects for the final rule. EPA does not currently have a sufficiently 

robust methodology to assess the impact of all possible changes in employment and quantify 

those changes. Moreover, based on the available evidence from several peer-reviewed 

econometric studies that are applicable to net employment effects in the regulated sectors (see 

Chapter 9 of the EA) and because closed-cycle cooling was rejected as national BTA for 

entrainment, EPA expects that employment impacts of today’s rule are not likely to be 

substantial. In EPA’s view, the qualitative employment effects analysis undertaken for the final 

58 For a discussion of input-output models see Chapter 8 of the EPA Handbook on the Benefits, Costs, and Impacts 

of Land Cleanup and Reuse (2011). 

Essay 59 357 
rule is appropriate to produce an informed regulatory result and therefore satisfies the 

requirements of the Executive Order 13563: Improving Regulation and Regulatory Review. 

EPA Should Consider the Current State of the U.S. Economy

EPA considered the costs of the rule and related possible impacts of these costs on the U.S. 

economy. See Essay 37. 

Failure to Consider the Costs and Effects of Other Rules

EPA disagrees; see Essay 29. 

Need to Assess Reliability Effects

EPA addresses reliability effects in Essay 45. EPA used the most up-to-date IPM platform 

available at the time EPA conducted the IPM analysis for the final rule, so all relevant final rules 

are taken into account in the analysis. EPA cannot incorporate into its analyses, including its 

IPM analysis, rules that have not been finalized because it would be impossible to predict with 

certainty in advance what the final rule will actually be. 

Need for Performance Metrics Pursuant to EO 13563

See Essay 48. Also, the final rule requires data monitoring and reporting with precisely the 

objective of understanding the rule’s effectiveness – at the level of the individual regulated 

facility. Permit Directors will collect biological characterization and other performance-related 

data for the initial post-promulgation permit, and then with each successive permit renewal. 

Permit Directors will use this information to evaluate the performance of compliance approaches 

and to adjust permit requirements at the time of permit renewal. 

Rule Does Not Set Performance Objectives

EPA disagrees. See Essays 10 and 14. 

Essay 59 358 
Essay 60: Other Federal Statutes

One commenter indicated that EPA has a duty under a number of Federal statutes to protect and 

conserve wildlife, and to cooperate with other Federal agencies in the protection and 

conservation of wildlife. In this connection, the commenter pointed to a number of statutes, 

including the National Environmental Protection Act, the Endangered Species Act (ESA), the 

Fish and Wildlife Coordination Act, the Bald and Golden Eagle Protection Act, the Migratory 

Bird Treaty Act, the Migratory Bird Conservation Act, the Marine Mammal Protection Act, the 

Wilderness Act, the Coastal Zone Management Act (CZMA), the Magnuson-Stevens Fishery 

Conservation and Management Reauthorization Act of 2006 (Magnuson-Stevens), Federal Land 

Policy and Management Act, and the National Forest Management Act. The commenter states 

that EPA could not promulgate the final 316(b) rule without meeting its particular duties under 

these acts. 

EPA notes that the commenter’s statement was an overarching statement that covered a broad list 

of possibly applicable statutes and did not include any specific concerns, signaled by details or 

other information. EPA’s rule complies with these many statutes and furthers their objectives. 

Furthermore, with respect to these statutes generally, EPA’s final rule ensures broad cooperation 

between EPA, State permitting authorities and other Federal agencies to protect and conserve 

wildlife by establishing a permitting process that will ensure full ventilation of these wildlife 

conservation issues. In the case of EPA’s duties under ESA, as explained in detail in DCN 12­

4543, EPA has consulted with the U.S. Fish and Wildlife Service (FWS) and National Marine 

Fisheries Service (NMFS) (collectively, “the Services”) under section 7 of the ESA on today’s 

final rule. As to the other statutes, the contours of the final rule reflect EPA’s efforts to ensure 

full coordination and cooperation with other Federal agencies exercising responsibilities under 

these statutes. 

The final rule requires the Director to establish impingement and entrainment controls in a 

facility’s NPDES permit, based on the BTA standards promulgated today. As explained in detail 

elsewhere, the Director determines these permit conditions in a structured setting in which the 

permit application requires the provision of detailed information characterizing the biological 

community in the vicinity of cooling water intake structures. This information must identify all 

Federally-listed threatened and endangered species and/or designated critical habitat that are or 

may be present in the action area. The rule requires that the Director must transmit the 

application to the appropriate Field Office of the FWS and/or Regional Office of NMFs upon 

receipt as well as, among other things, subsequently providing them copies of any draft permit. 

The information sharing provisions of this rule and the opportunity for the Services to make 

suggestions prior to the NPDES permitting decision will facilitate the FWS and NOAA’s 

implementation not just of the ESA but also of many of the statutes listed above (e.g., the Fish 

and Wildlife Coordination Act, the Bald and Golden Eagle Protection Act, the Migratory Bird 

Treaty, the Migratory Bird Conservation Act and the Marine Mammal Protection Act). EPA’s 

permit application requirements ensure that FWS and NMFS – and other Federal agencies as 

well -- will have a broader information base from which to make informed decisions. Thus, the 

rule provides ample opportunity for the Services to identify concerns related to any specific 

NPDES 316(b) permit and requirements under other statutes during the permit issuance process. 

Essay 60 359 
Consequently, the Director will have adequate information before him to develop control 

measures and monitoring and reporting requirements that will provide adequate protections to 

species. Further, the final rule provides the Director with explicit authority to require additional 

measures to protect Federally-listed T&E species and designated critical habitat. 

For the final rule, EPA has also complied with its duties under Magnuson-Stevens, as well as the 

CZMA. Section 305(b)(2) of Magnuson-Stevens requires that “[e]ach Federal agency shall 

consult with the Secretary [of Commerce] with respect to any action authorized, funded or 

undertaken, or proposed to be authorized, funded, or undertaken, by such agency that may 

adversely affect any essential fish habitat identified under the statute]...” 16 U.S.C. § 1855(b)(2). 

Because the effect of the implementation of EPA’s rule through NPDES permits will be to 

ameliorate current conditions with respect to the impingement and entrainment of aquatic 

organism, EPA’s 316(b) rulemaking will not “adversely affect” any essential fish habitat and 

consultation was not required. The effects on essential fish habitat from the imposition of 

restrictions on cooling water intake structures will be beneficial. 

EPA similarly concluded that the requirement of the CZMA for a consistency determination for 

certain Federal agency activities was not implicated by its 316(b) rule. This is because the final 

rule is not an activity under the Act, as it does not physically alter coastal resources or alter uses 

of the coastal zone. Further, no commenters specifically explained how this rule in any way 

would affect the coastal zone or be inconsistent with any enforceable policy of any coastal zone 

management plan. Even if it did in some way have any such effect, which it does not, any such 

effects will be addressed in the subsequent permitting proceeding. This approach is consistent 

with the preamble to NOAA’s amendments to the Part 930 regulations, where NOAA stated that 

there are circumstances where rulemaking actions are not subject to federal consistency review 

because 1) they “do not authorize activities with coastal effects,” and (2) even if they did result 

in activities with coastal effects, the activities and coastal effects would be addressed in a 

subsequent consistency review. 71 Fed Reg. 788, 792, 807 (2006). In forty-six states, the State is 

the permitting authority and will coordinate with the “State agency” designated to administer the 

approved coastal zone management program. In the very few states where the EPA issues the 

NPDES permit, the EPA will undertake any required CZMA consultation with the appropriate 

coastal zone management program. EPA’s NDPES permitting regulations specifically require 

adherence to the CZMA when issuing NPDES permits at 40 C.F.R. § 122.49(d) and prohibits 

EPA from issuing an NPDES permit unless the applicant certifies that its activity complies with 

the State’s program or the State concurs with the certification. 

Essay 60 360 
Essay 64: Inter‐Agency Review

Multiple commenters raised issues concerning the extent of review and participation by other 

agencies in developing the proposed rule. In particular, the Louisiana Department of 

Environmental Quality argued that EPA should encourage agencies such as the Army Corps of 

Engineers, Coast Guard, Occupational Safety and Health Administration, and Department of 

Commerce to review the rule, as it will affect the navigation of waterways, worker safety, and 

commerce. 

Riverkeeper criticized OMB’s review and participation in development of the proposed rule. 

EPA disagrees that it did not seek review and comment from other agencies in developing the 

proposed rule. Specifically, EPA conducted an interagency review under OMB pursuant to EOs 

12866 and 13563, which provided all interested Federal agencies with the opportunity to review 

and comment on the draft regulation. Also, more than 40 state government agencies submitted 

comments on the proposal and seven additional agencies submitted comments on the NODA. 

Regarding OMB’s participation in developing the proposed rule, EPA submitted the proposed 

and final rule to OMB for review in accordance with EO 12866. OMB’s participation in the 

rulemaking process is part of the ordinary process for interagency review, as required by law. 

Essay 64 361 
Essay 68: New Capacity

In the Federal Register publication for the proposed rule, EPA requested comment on the number 

of new units and the amount of new capacity construction projected. Several commenters 

responded to this request with “no comment.” Riverkeeper responded with a comment on the 

quantity of capacity that might retire early because of the existing facilities rule, and indicated 

that new capacity additions would offset any capacity losses due to early retirement. 

EPA agrees that only a small quantity of generating capacity would be expected to retire 

prematurely because of the existing facilities rule. Comments to this effect are consistent with 

the results EPA obtained on potential capacity effects from its IPM-based electricity market 

analysis undertaken for the final rule. EPA agrees that any capacity effects due to the final rule 

will be managed within the electricity supply system without adverse impact on electric supply 

reliability or electricity rates. EPA views this finding as supportive of the Agency’s 

determinations regarding requirements of the final rule. 

Essay 68 362 
Essay 70: General Comments on Nonuse Benefits

EPA received a number of comments on the issue of nonuse benefits arising from the 

impingement and entrainment (I&E) controls under the regulatory options. This essay responds 

to those comments. Additional essays respond to specific issues related to the estimation of 

nonuse benefits. 

In comments 2200, 2210, 2192, and others, the Electric Power Research Institute (EPRI), the 

Utility Water Act Group (UWAG), PSEG Services Corporation, and others commented on what 

they considered to be EPA’s reliance on nonuse values to justify the costs of the rule, the 

likelihood that these values are significant, and the application of EPA’s methods to site-specific 

analyses. For example, two private citizens find EPA’s figures puzzling, specifically asserting 

that the broad range of annualized nonuse benefits is unreasonably expansive, and that EPA fails 

to explain the range. These commenters also cite Data Quality Act (DQA) and EPA guidelines in 

questioning the quality of this information. 

In comment 2156, the Edison Electric Institute (EEI) finds that nonuse benefits are unlikely to 

justify the rule’s costs, and calls EPA’s assumption that the public will perceive enormous 

nonuse benefits from marginal increases in populations of little-known forage fish, a serious 

error. In comment number 2200, EPRI states that there is a large difference between quantified 

benefits and costs and no description of the record that indicates that nonuse values will be 

sufficient to make up this difference. EPRI supposes that the record potentially includes EPA’s 

habitat basis for estimating nonuse values and breakeven analysis for the proposed rule, as well 

as analyses conducted for the proposed 2004 promulgated rule (Habitat Replacement Cost, 

Societal Revealed Preference, the Fisher-Raucher Approximation, and Production Foregone). 

EPRI claims that currently, none of this “record” is indicative of reliably estimated benefits of a 

magnitude that exceed the costs of the rule. 

In comment 2156, the EEI points to comments by NERA Economic Consulting which state that 

the key issue is how benefit-cost decisions should be made when there is no reliable information 

on nonuse benefits. NERA asserts, “... EPA appears to rely upon the possibility of nonuse 

benefits to justify a decision to require impingement controls at all plants/facilities, even when 

the estimated “use” benefits are a small fraction of the estimated social costs. If this logic were 

used by individual permit writers, very expensive entrainment controls (such as cooling towers) 

could be “justified” on benefit-cost grounds.” 

In comment 2192, PSEG Services Corporation points to its 2006 permit renewal application for 

Salem, stating that nonuse values are not appropriate in most instances because the benefits of 

most organisms lost to entrainment (and impingement) have otherwise been monetized. If 

nonuse benefits were relevant, it would be very difficult to monetize the benefits in an 

appropriate and defensible manner. In contrast to EPA’s position that nonuse values are 

important because most organisms lost do not have a direct use value, PSEG claims to have 

consistently been able to estimate benefits for all of the organisms entrained through wellestablished trophic transfer methodologies that estimate values for forage organisms by 

converting the pounds lost to pounds of commercially or recreationally important species. 

Essay 70 363 
In comment 2210, UWAG states that EPA appears to rely upon the possibility of additional 

nonuse benefits to justify a decision to require impingement controls at all plants/facilities, and 

that it is arbitrary and irrational simply to assume, without empirical evidence, that people will 

be willing to pay the cost of EPA’s program no matter what it is, provided it amounts to mere 

pocket change when divided among all the households in the country. UWAG further states that 

EPA should require that benefit studies in site-specific assessments use specific criteria to 

determine the likely significance of nonuse benefits. If these criteria indicate that nonuse benefits 

are not likely to be significant, the site-specific assessment should not require that they be 

quantified, citing EPA criteria from earlier rulemaking. UWAG cites Freeman (2003; DCN 12­

4815) for a review of the literature on nonuse values and situations in which nonuse values are 

likely to be significant when the resource in question is special or unique and the loss or injury is 

irreversible (or subject to a prolonged recovery). UWAG concludes that in most cases involving 

section 316(b), Freeman’s criteria are not likely to be satisfied. UWAG also states that nonuse 

benefits may be negative if undesirable fish are affected, with the example of alewife in the 

Great Lakes, and that EPA does not adequately consider the possible ecological costs of cooling 

towers. 

EPA disagrees with these comments. The preamble to the final rule fully describes EPA’s 

reasoning for selecting the best technology available for minimizing adverse environmental 

impacts from cooling water intake structures (CWIS). Specifically, EPA first considered the 

availability and feasibility of various technologies, the costs (including potential costs to 

facilities and households), and the economic impacts associated with these technologies. EPA 

reviewed the efficacy of these technologies in reducing impingement mortality and entrainment. 

EPA also considered additional factors set out in CWA section 304(b), including location, age, 

size, and type of facility. EPA next considered the non-water quality environmental and other 

impacts of different technologies on energy production and availability, electricity reliability, 

and potential adverse environmental effects that could arise from the use of the different 

technologies evaluated. 

As described in the preamble, as a result of this thorough evaluation, EPA is establishing a rule 

that includes a BTA standard for impingement mortality based on modified traveling screens 

with a fish handling and return system whose performance has been optimized to minimize IM. 

A facility has several alternatives for compliance. For entrainment, EPA establishes a detailed 

regulatory framework for the determination of BTA entrainment requirements by the permitting 

authority on a site-specific basis. EPA identified the following specific factors as the key 

elements in its decision not to prescribe a single technology, closed-cycle cooling as the basis for 

a national BTA determination: land availability, air emissions, and remaining useful plant life. 

The preamble also describes the record and EPA’s determination that the impingement mortality 

and entrainment controls will result in benefits that justify the costs of the rule. EPA describes 

that it was able to generate only a partial estimate of benefits for the rule. In particular, EPA’s 

analysis does not fully quantify or monetize certain potentially important categories of benefits, 

such as existence values for threatened and endangered species, secondary and tertiary 

ecosystem impacts, benthic community impacts, shellfish impacts and the impacts arising from 

reductions in thermal discharges that would be associated with closed-cycle cooling. Changes in 

fish assemblages due to impingement, entrainment and thermal effects are also not fully 

quantified or valued. 

Essay 70 364 
As discussed in the preamble, EPA may consider, but is not required to consider, the costs and 

benefits associated with various control options. In addition, EPA explains (in section II.C and 

VI.E of the preamble) why consideration of costs and benefits is appropriate in the site-specific 

determinations when establishing entrainment controls. In the site-specific proceeding, the 

Director is to consider, among other factors, quantified and qualitative social benefits and social 

costs of available entrainment controls, including ecological benefits and benefits to any 

threatened or endangered species. The Director may reject otherwise available entrainment 

controls if the costs of the controls are not justified by their associated benefits (taking into 

account both quantified and non-quantified benefits), and the other factors discussed in the final 

rule. In evaluating benefits, the Director should not ignore benefits that cannot be monetized or 

consider only the I&E reductions that can be counted. To result in appropriate decisions from 

society’s standpoint, the assessment of benefits must take into account all benefits, including 

categories such as recreational, commercial, and other use benefits; benefits associated with 

reduced thermal discharges; reduced losses to threatened and endangered species; altered food 

webs; benefits accruing non-locally due to migration of fish; nutrient cycling effects; and other 

nonuse benefits. Merely because it is difficult to put a price tag on those benefits does not mean 

that they are not valuable. EPA notes that Executive Order 13563 recognizes that some benefits 

are difficult to quantify, and calls for agencies and departments to consider qualitative benefits. 

A national evaluation of benefits, no matter how accurate, would fail to account for the 

variations in benefits from location to location. On the basis of available information, EPA’s 

analysis of benefits relied on extrapolating data from existing I&E characterization studies to all 

facilities in the same region on a flow-weighted basis. Differences in species, life stages, and 

biological abundance across intake locations (even within a region) could lead to very different 

results for a site-specific analysis of a facility as compared to that facility’s share of national 

costs and benefits, even if the national results are, on average, accurate. A national assessment 

tends to mask variations in benefits and costs from different geographical locations for different 

waterbodies. For example: 

	 Some fish species at coastal facilities have biological spawning attributes that differ from 

those at other locations. 

	 The proportion of the receiving water withdrawn for cooling could also vary among sites. 

	 The values that communities place on their resources could vary from site to site. 

	 One ecological environment might experience large masses of hardier eggs and larvae 

subject to potential entrainment; another will have fewer but less hardy eggs and larvae 

susceptible to entrainment. Without detailed study information, it is difficult to ascertain 

which facility has the greater adverse environmental impact. 

The resulting differences in the value of reduced entrainment—which could be dramatic for 

some sites—necessarily disappear in a national aggregation of results. The Agency has decided 

that this masking of variation in benefits further supports EPA’s decision to require consideration 

of the site-specific benefits of entrainment control technologies in the site-specific process to 

establish entrainment controls. 

Essay 70 365 
EPA disagrees with PSEG’s assertion that trophic transfer methods are appropriate for estimating 

the benefits of all entrained organisms. Most of the value for forage fish is nonuse because most 

are not consumed by recreational or commercial species, or caught. The portion of the value that 

the commenter is estimating by converting the pounds lost to pounds of commercially or 

recreationally important species is the indirect use value. Therefore, the indirect use value 

determined through trophic transfer methods has no bearing on the magnitude of nonuse value 

for the remainder of forage fish. 

EPA disagrees with UWAG’s assertion that the Agency assumes that people are willing to pay 

no matter what the rule costs, or that it has no empirical evidence of WTP. Focus groups provide 

evidence that most people have positive WTP for reducing fish mortality at CWIS (U.S. EPA 

forthcoming; DCN 12-4656). EPA also found, as described in the benefits analysis 

accompanying the final rule, that WTP varied with the amount of fish protected. The preamble to 

the final rule describes how EPA considered economic factors, and that some costs and benefits 

are difficult to quantify. 

EPA acknowledges that in previous rulemaking it established criteria for permittees and permit 

writers to use in determining whether to monetize nonuse benefits. These criteria do not change 

EPA’s decision regarding addressing nonuse benefits in site-specific decision-making for today’s 

rule. As stated in the preamble, EPA recognizes the resource limitations faced by permitting 

authorities, and is committed to working with the states to support their site-specific permitting 

decisions. The benefits assessment would typically look at a range of potential benefit 

mechanisms, including increased harvest for commercial fisheries, increased use values for 

recreational fisheries, and nonuse values (existence and bequest values). EPA recognizes that the 

latter may be difficult to quantify or monetize. If appropriate data are available from benefits 

transfer or conducting stated preference studies or other sources that can be applied to the site 

being evaluated, these should be used to monetize nonuse values. Otherwise, nonuse values 

should be evaluated qualitatively. 

EPA disagrees with UWAG’s assumption that nonuse values of reducing I&E losses are trivial. 

EPA is aware of no research—empirical or otherwise—that demonstrates that individuals have 

limited or no existence values for the aquatic resources affected by the 316(b) regulation. 

To the contrary, prior research demonstrates public willingness to pay for similar types of 

resource improvements to those addressed here (e.g., Johnston et al. 2011; DCN 12-4866; 

Johnston et al. 2012; DCN 12-4865). Moreover, there are no theoretical necessary conditions for 

the existence of nonuse values. For example, resources do not have to be unique to be the source 

of nonuse WTP. While factors such as uniqueness can affect willingness to pay, the significance 

of nonuse values depends on individual responses to given conditions. Although the EPA 

recognizes the possibility of low nonuse values in this case, significant nonuse values are also a 

strong possibility. EPA notes that when a substantial fraction of the population holds even small 

per capita nonuse values, these nonuse values can be very large in the aggregate. As stated by 

Freeman (2003, p. 138; DCN 12-4815), “If nonuse values are large, ignoring them in natural 

resource policymaking could lead to serious errors and resource misallocations.” Both EPA’s 

own Guidelines for Preparing Economic Analysis and OMB’s Circular A-4, governing 

regulatory analysis, support the need to assess nonuse values (USEPA 2010; DCN 12-5027; 

USOMB 2003; DCN 12-5043). 

Essay 70 366 
Regarding the effect of the presence of undesirable species on nonuse benefits, EPA agrees that 

invasive species may represent a disamenity, although anglers may hold value for some 

introduced species (e.g., salmon in the Great Lakes). EPA disagrees that the nonuse value of 

reducing impingement mortality and entrainment under the rule is negative. EPA notes that: (1) 

undesirable species represent only a very small fraction of organisms saved under the final rule, 

and (2) the Agency did not estimate nonuse benefits for the Great Lakes region using a benefit 

transfer approach because it did not identify a benefit transfer study that would provide a good 

match to the fisheries resources affected in the Great Lakes region. 

Regarding the ecological costs of cooling towers, of the examples of categories that EPA is 

aware of, the likelihood of the ecological cost is sufficiently low that EPA has no reason to 

change its decision about the BTA in today’s rule. 

Essay 70 367 
Essay 71: Benefit Categories

EPA received a number of comments on the economic benefit categories associated with 

impingement mortality and entrainment (IM&E) reduction. This essay responds to those 

comments. 

Excluded Benefit Categories

In comment 2391, Riverkeeper states that EPA’s benefits calculations include only parts of the 

two direct use categories of benefits from IM&E losses, and an estimate of nonuse values for two 

regions of the country. With respect to use values, Riverkeeper commented that EPA did not 

estimate the following types of indirect-use, marketed-goods benefits: increases in equipment 

sales, rental, and repair; bait and tackle sales; consumer choices in stores and restaurants; 

property values near the water; and ecotourism. Riverkeeper also commented that EPA did not 

estimate direct-use benefits from non-market goods, including increases in rates of participation 

in recreational fishing, and the improved value of subsistence fishing; and the increased value of, 

and increased participation in, boating, scuba diving, and near-water recreation based on 

enjoying observation of fish (or of birds catching fish). With respect to nonuse values, 

Riverkeeper commented that EPA offers a benefits transfer estimate of nonuse values for only 

two of the seven regions of the country, along with what Riverkeeper finds to be a conceptually 

mistaken (and quantitatively trivial) estimate of the unique value attached to threatened and 

endangered species. Riverkeeper further points to EPA’s original discussion of the limitations of 

the benefits calculations (“Original CWIS rule, p.166”). 

In comment 1968, the commenter asks why qualitative benefits of recreational fishing were “ten 

times more “valuable” than the quantifiable benefits of commercial fishing.” 

EPA agrees that the estimates of use and nonuse benefits are incomplete, but has done the best 

job at estimating benefits that it could, given limitations in data, information and tools for 

estimating benefits. EPA acknowledges that the list of use values presented by the commenter 

include potential benefit categories. The difficulty is having enough data on these behaviors and 

expenditures, and being able to link increased fishing success (from fish protection at CWIS) to 

increases in these items. However, EPA does not expect that these indirect-use market benefits, 

had EPA been able to calculate them, would have been significant enough to affect the choice of 

BTA in today’s rule. 

In the absence of complete estimates of nonuse benefits, EPA estimated partial nonuse benefits 

for the final rule using a benefits transfer approach. This approach is still a partial estimate 

because it concerns only one species in two coastal regions. EPA fully documents these 

limitations to practical implementation of cost-benefit analysis in the record for the rule, and 

explains fully in the preamble how the information from the analysis factored into its decisionmaking. 

For example, as described in the preamble to the final rule in Section VII. Response to Major 

Comments on the Proposed Rule and Notices of Data Availability (NODAs), EPA considered 

both monetized and nonmonetized benefits, and has concluded that the benefits of the rule justify 

Essay 71 368 
the costs when all categories of benefits of the final 316(b) regulation are considered. With 

respect to entrainment, the rule authorizes the Director to consider costs and benefits on a sitespecific basis. With respect to impingement mortality, the rule provides seven compliance 

alternatives based on a set of widely used, demonstrated, proven technologies, many of which 

have been in use for decades and the efficacy of which is well-supported in EPA’s record. 

By reducing impingement mortality and entrainment, the final existing facilities rule is likely to 

increase the number of fish, shellfish, and other aquatic organisms in affected waterbodies 

resulting in healthier aquatic environments. In turn, this healthier aquatic environment directly 

improves welfare for individuals using the affected aquatic resources. It generates use benefits 

such as increases in the value of recreational and commercial fisheries, or increases in property 

values, which may reflect increased use values. Reductions in impingement mortality and 

entrainment also improve welfare for individuals without use of the affected resources, and 

generate nonuse benefits, such as existence of healthier ecosystems and resource bequest values. 

EPA notes that qualitative benefits, by definition, are not monetized, and so cannot be cardinally 

compared to monetized benefits. EPA also notes that both recreational and commercial fishing 

benefits were quantified and monetized for the final rule. The relationship between commercial 

and recreational fishing benefits resulting from environmental improvements depends on many 

factors including the species affected, the magnitude of commercial versus recreational harvest 

(e.g., in some cases only recreational harvest is allowed), the presence of a commercial fishery 

(e.g., fish in some waters are below harvestable or marketable size), and the market and 

nonmarket value of the incremental catch. EPA notes that while commercial fishing benefits are 

based on the market value of incremental catch, recreational fishing benefits reflect anglers’ 

willingness to pay for the enhanced fishing experience and depend on both willingness-to-pay 

for an increased catch rate and angler populations. It is possible for fishing benefits to be only 

recreational, and for recreational fishing benefits to exceed commercial fishing benefits where 

both types of fisheries exist. For example, the Agency estimated substantive recreational benefits 

and no commercial fishing benefits stemming from the final rule for the Inland region (see 

Chapters 6 and 7 in the BA). 

Economic and Cultural Benefits

Commenters stated that America’s fisheries also provide enormous economic and cultural 

benefit that should be protected. For the Great Lakes specifically, a commenter provided studies 

indicating that investment in protection yields an even greater return in economic benefits to the 

region. According to the commenter, once-through cooling water withdrawals from the Great 

Lakes are a key contributor to fish population loss and ecosystem decline, and allowing the 

activity to continue is inconsistent with the evidence of the economic growth and opportunities 

of restoration and the spending of hundreds of millions of dollars to protect and restore the Great 

Lakes. 

EPA agrees that the nation’s fisheries need and are worth protecting, and that restoration of the 

Great Lakes will yield large economic and cultural benefits. EPA has considered these benefits 

in developing the final rule. For example, as described in the preamble to the final rule, in 

assessing the benefits of entrainment technology installation, the Director would assess the value 

to society from the reductions in impingement mortality and entrainment that would result from 

Essay 71 369 
installation of a closed-cycle cooling system, fine mesh screens, or other impingement and 

entrainment technologies. All benefits, including monetized, quantified and qualitative benefits, 

should be considered in this assessment. 

EPA disagrees that the rule is inconsistent with the protection of economic and cultural 

resources. The preamble to the final rule describes in detail the factors EPA considered in 

selecting BTA for impingement mortality and entrainment, which include economic factors, and 

recognition that all costs and benefits may be difficult to quantify. Further, the final rule does not 

preclude taking cultural or regional site-specific decision-making. The final rule for existing 

facilities establishes a detailed regulatory framework for determining BTA entrainment 

requirements by the permitting authority on a site-specific basis. The rule identifies what 

information must be submitted in the permit application, prescribes procedures that the Director 

must follow in its decision-making, and factors the Director must consider in determining what 

entrainment controls will represent the BTA requirements on a site-specific basis. 

EPA does not include a specific category of subsistence fishing benefits in the analysis. 

However, because EPA uses the value of catching an additional fish to value recreational fishing 

benefits in conjunction with the total increase in noncommercial catch, the benefits to 

subsistence fishers are included in this estimate. This is despite the fact that EPA does not 

allocate the total change in recreational (or rather, noncommercial catch) between subsistence 

and recreational fishers because data on the extent of subsistence fishing are not available. Also, 

separate willingness to pay (WTP) estimates for changes in catch rates for substance fishers are 

not available in economic literature. If WTP for changes in catch rates for subsistence fishers is 

significantly different from recreational fishers, the recreational benefits may be over or 

understated. 

EPA also does not include a specific category of cultural benefits in the analysis because 

separate estimates for this category are not available. Moreover, the current valuation literature 

advocates the use of total values as opposed to summing separate categories. EPA also does not 

include a specific category of cultural benefits in the analysis because separate estimates for this 

category are not available. Moreover, the current valuation literature advocates the use of total 

values as opposed to summing separate categories. Accordingly, EPA used benefit transfer to 

estimate total WTP (including aesthetic, cultural, and other use and nonuse values) for reducing 

fish mortality in the Northeast and Mid-Atlantic regions, and does not estimate cultural or 

aesthetic benefits separately. EPA was unable to quantify total WTP for reducing IM&E 

mortality using the benefit transfer for Inland, South Atlantic, Gulf of Mexico, and CA regions 

due to data limitations. EPA’s also used the 316(b) stated preference survey to estimate total 

WTP for all regions and has included the estimates in Chapter 11 of the BA for illustration 

purposes. Estimates based on the 316(b) stated preference survey are not included in the costbenefit comparison for the final rule. 

Accordingly, EPA estimated total WTP (including aesthetic, cultural, and other use and nonuse 

values) for reducing fish mortality in the Northeast and Mid-Atlantic regions, and does not 

estimate cultural or aesthetic benefits separately. EPA was unable to quantify total WTP for 

reducing IM&E mortality for Inland, South Atlantic, Gulf of Mexico, and CA regions due to data 

limitations. 

Essay 71 370 
Site Benefits

A commenter states that the rule should make clear that benefits, whether quantitative or 

qualitative, must be likely to occur at the site in question, that impacts on aquatic life must be 

more than theoretical, and the likelihood of the risk should be evaluated based on all the 

available evidence for the site. Another commenter stated that, in general, greater emphasis 

needs to be placed on adequately assessing the benefit side of any cost-benefit analysis - the 

costs of compliance options will be determined by the facilities owners in very quantifiable terms 

of dollars. 

EPA disagrees that the benefits have to occur at a particular site to be considered as benefits 

associated with fish protection at that site. Because many fish migrate, preventing the death of 

larvae in one location may result in local benefits only or benefits being realized on a much 

larger geographic scale. EPA disagrees that impingement mortality and entrainment controls 

yield theoretical benefits. However, as noted above, the preamble to the rule describes fully the 

site-specific decision-making for entrainment controls under the rule. 

EPA agrees with the comment regarding emphasis in cost-benefit analysis. Costs of compliance 

are typically more readily discernable than the environmental benefits, the inclusion of which are 

often limited by data and the current state of scientific and economic understanding. 

Distributional Effects

One commenter referred to dubious cost-benefit calculations at administrative agencies, and past 

comments to EPA in which they noted that agencies have counted costs imposed on businesses 

as benefits to the broader economy. 

EPA disagrees that it has counted the estimated costs of the proposed rule as social benefits. 

Compliance costs, regardless of any stimulating impacts of construction work on the economy, 

do not represent benefits. However, the environmental improvements resulting from the 

installation of compliance technologies may have indirect economic benefits in the form of 

stimulating business activity such as equipment or bait sales associated with an increase in 

recreational or commercial fishing activities. This related stimulating effect would represent 

benefits of the proposed rule, although EPA was not able to quantify such benefits for the final 

rule. 

Essay 71 371 
Essay 72: Benefits to Threatened and Endangered Species and

Endangered Species Act Consultation

EPA received several comments on the benefits of the rule to threatened and endangered (T&E) 

species. This essay responds to those comments. 

Monetized Benefits of Threatened and Endangered Species

In comment 2260, New York State Department of Environmental Conservation (NYSDEC) 

stated that EPA has not appropriately characterized the social value of reducing the impingement 

and entrainment of T&E species. Society has already indicated that it places a high value on 

T&E species protection, which is already provided by current law. Fines for illegally taking 

several aquatic organisms commonly impinged by CWIS, and the funding of efforts to restore 

populations of affected species, are reflective of this value and protection. If EPA assessed the 

nonuse value of all T&E species that are impinged annually, these alone would provide the cost 

benefit justification for EPA to select Option 2 or 3 and require closed-cycle cooling or the 

equivalent as BTA for the national rule. 

In comment 2188, National Wildlife Federation (NWF) states that the protection of Federallylisted species is paramount, and protection of these species cannot be weighed against a costbenefit analysis. Further, with this rule, the cost of protecting these species is low. Therefore, 

rather than wrestle with difficult to quantify “nonuse” values, EPA should require closed-cycle 

cooling and ensure that the risks to T&E from power plants are greatly reduced. 

EPA agrees that it has not been able to fully monetize the value of T&E species in the monetized 

benefits estimates for the rule. As described in the preamble, EPA concluded that the costs of the 

rule are justified by the benefits, which includes considering the unmonetized benefits, including 

T&E species. However, as explained in the preamble, EPA did not reject closed-cycle cooling on 

the basis of costs and benefits. EPA rejected closed-cycle cooling as the technology basis for a 

uniform national BTA entrainment standard based on three factors: land availability, air 

emissions, and remaining useful plant life. 

EPA also notes that its stated preference survey of use and nonuse benefits of reducing 

impingement mortality and entrainment (IM&E), which it did not incorporate into the costbenefit analysis for the final rule, does not specifically refer to T&E species (in order to be more 

generally applicable). It is an open question as to whether the survey results fully capture these 

benefits. 

Assumptions Regarding Baseline Losses

In comment 2391, Riverkeeper disputed the seemingly arbitrary percentages of the affected 

populations attributable to baseline impingement and entrainment that EPA used in developing 

the estimates that it did not include in the overall estimate of benefits (0.25 percent or 0.5 percent 

reduction in the Inland region T&E species; and a 1 percent reduction in endangered sea turtle 

populations), noting that the results are dependent on the assumed percentages. Riverkeeper 

asked why EPA selected these percentages rather than others. Since elsewhere EPA considers a 1 

Essay 72 372 
percent losses for sea turtles, and uses estimates as high as 6.6 percent baseline losses for winter 

flounder in the North Atlantic and Mid-Atlantic, Riverkeeper suggests using numbers that fall 

between the sea turtle and winter flounder loss estimates, such as 2 percent or 4 percent losses of 

Inland region T&E species. Riverkeeper notes that the fact that species are classified as T&E 

implies that their numbers are limited, and that annual mortality of a few percent due to cooling 

water intake does not seem impossible. 

With respect to the percentages EPA employed in the illustrative estimate of benefits, EPA 

points out that, for sea turtles, the percentage does not represent a change in population but a 

percentage decrease in the probability of extinction for sea turtles. EPA did not have adequate 

data to estimate this probability. However, as an illustrative example, EPA used a 1 percent 

decrease in the probability of extinction over 25 years for sea turtles as an extremely high 

boundary condition. The number of takings that NOAA permits by shrimp and high seas longline 

fisheries, as well as military operations, is orders of magnitude greater than the permitted number 

of takings by regulated facilities, and yet these activities have Incidental Take Statements 

because they are unlikely to jeopardize the continued existence of species (NOAA, 2012; DCN 

12-5081). 

Winter flounder is not a T&E species. EPA conducted a benefits transfer to estimate nonuse 

values based on winter flounder. As such, the estimates of winter flounder mortality due to 

IM&E are not relevant in the context of T&E species. Winter flounder are commercially targeted 

species, and commonly appear in facility IM&E studies. Species protected by the ESA cannot be 

targeted commercially, and rarely (if ever) appear in IM&E studies. Consequently, using 

mortality estimates of winter flounder would be inappropriate in the context of estimating effects 

of the rule on T&E species. 

For inland species, less data are available, and the data are older; documented IM&E of T&E 

species in the Inland region come from a single study in 1976. Additionally, many inland species 

(e.g., pallid sturgeon) have extensive restocking programs that make estimating the effects of 

IM&E on populations extremely difficult. Given these uncertainties and that the WTP study EPA 

used in developing its benefit estimates reflects population changes across all species, an 

estimated population change of 0.25 percent – 0.5 percent represents a reasonable estimate of the 

likely effects of CWIS. 

Essay 72 373 
Essay 73: Commercial and Recreational Fishing Benefits

EPA received a number of comments on its analysis of commercial and recreational fishing 

benefits. This essay responds to those comments. 

Fishery Yield

The model for estimating changes in fishery yield is common to the analysis of commercial and 

recreational fishing benefits. In comment number 2391, Riverkeeper states that the use of a 

global average trophic transfer value may not be appropriate for the individual regions evaluated 

by EPA, and that the detailed local data developed for these regions by EPA should be 

accompanied by local calculations of trophic transfer rates. In comment number 2200, the 

Electric Power Research Institute (EPRI) states that the approach applied to the rule benefit 

analysis to calculate changes in fishery yield in the 316(b) context is an approximation that does 

not consider important biological processes such as compensation and reproduction. 

Regarding the average trophic transfer value, EPA responds that, notably, the values of trophic 

efficiency (TE) compiled by Pauly and Christensen (1995; DCN 12-4954) are not habitat 

specific, but are specific to trophic-levels within specific geographic regions (e.g., the 140 

estimates come from 48 food webs). The raw data indicate substantial variability not only among 

sites within aquatic ecosystem (e.g., freshwater ponds and lakes, coastal areas, shelves and open 

ocean), but also among trophic levels within sites (e.g., TE within Lake Kinneret varied between 

3 and 19 percent) (Christensen and Pauly, 1993; DCN 12-5070). Accordingly, because of the 

complexity of multi-species food webs and the trophic-level, and the location-specific nature of 

trophic transfer rates, EPA did not develop individual estimates at local or regional scales but 

used the average rate. EPA agrees that calculating changes in fishery yield is an approximation 

that does not consider important biological processes. However, it is not clear that the effects of 

these processes would play a substantial role in changing the effects of impingement mortality 

and entrainment (IM&E) on fishery yield because populations of harvested fish are already quite 

depressed, and it is unlikely that intraspecies competition will play a substantial role in 

determining the number of harvestable fish. 

Commercial Fishing Market Complexity

In comment number 2458, the commenter notes that commercial fishing markets are complex 

and, as harvest increases, there may be a decrease in the dockside market price as a result of 

competition and fully accounting for market complexity could result in either overestimating or 

underestimating benefits. 

EPA understands that there are complexities in estimating dockside market prices, but expects 

changes in dockside prices resulting from the rule to be negligible due to relatively small 

changes in commercial fisheries landings under the various options considered for the final rule. 

As described in the BA, EPA measured commercial fishing benefits as changes in producer 

surplus assuming no change in the market price. EPA considered potential consumer surplus 

values associated with IM&E, but did not estimate changes in consumer surplus for the final rule 

and options considered because it found that dockside prices would not change enough to 

Essay 73 374 
produce measurable shifts in consumer surplus. See Chapter 6 of the BA for more detailed 

discussion of how EPA addressed changes in consumer and producer surplus for commercial 

fishing. 

Great Lakes Study

On the basis of a study of damages caused by IM&E at the Bay Shore Power Plant (BSPP) in 

Ohio (Gentner and Bur, 2009; DCN 12-5071), in comment number 2391 Riverkeeper claims that 

EPA’s estimates of baseline mortality of walleyes in the Great Lakes are low, in the hundreds of 

fish per year. The BSPP study, looking only at one Great Lakes plant, counted impingement of 

tens of thousands of walleyes per year in the data for that plant, along with entrainment of larvae 

amounting to hundreds of thousands of adult-equivalent fish. The commenter cites the same 

study by Gentner and Bur (2009; DCN 12-5071) to argue that EPA used an incorrect (lower) per 

fish value of walleye in the analysis of recreational fishing benefits. 

EPA agrees with the comment regarding the study data. After reviewing the study, EPA 

incorporated the data from the BSPP study into the BA. As a result, EPA’s estimates of mortality 

for walleye in the Great Lakes increased substantially, and recreational fishing benefits for the 

Great Lakes Region increased. See the BA for the revised estimates. 

EPA disagrees regarding the per fish value of walleye. EPA acknowledges that different primary 

studies report different values ranging from $3.66 to $22.63 per fish, with the majority of values 

being less than $10.00 (2004$); see U.S. EPA, 2006 (DCN 12-5024). EPA notes that the benefit 

value transfer described by the commenter may result in a different estimate compared to a 

benefits transfer based on a meta-analysis of relevant values of willingness to pay (WTP) for 

catching an additional fish per trip (hereafter per-fish WTP) [including values from a study by 

Besedin et. al (2004; DCN 12-5072) used by the commenter]. EPA also notes that the general 

consensus in economic literature is that function transfers typically outperform unit value 

transfers (Rosenberger and Stanley, 2006; DCN 12-5073), although contrary or inconclusive 

findings have been reported in the resource valuation literature (Brouwer and Bateman, 2005; 

DCN 12-5074). Finally, EPA points out that the authors chose a WTP estimate from Besedin et 

al. (2004; DCN 12-5072) for boat anglers ($18.43, in 2004$), and did not account for the WTP 

estimates for shore anglers which were significantly lower ($9.96, 2004$). EPA acknowledges 

that higher per fish WTP would increase benefits of the final 316(b) regulation, but not to the 

extent that EPA would expect to change the final rule option EPA selected because of the factors 

discussed in the preamble to the final rule. 

Recreational Fishing Benefits Analysis Method

In comment number 2200, EPRI states that EPA’s approach of applying marginal per-fish values 

to identify fishery impacts is not a standard approach for evaluating the economics of a fishery, 

and that a more thorough explanation of the limitations of the approach and the rationale for the 

approach would be helpful for making the analysis and rationale more transparent to 

stakeholders. The commenter argues that instead of using per-fish WTP to estimate changes in 

anglers’ welfare, the Agency should use the individual’s demand for fishing trips to recreational 

sites affected by the rule to estimate consumer surplus from an increase in the number of trips. 

The commenter claims that EPA’s approach for the analysis of benefits does not adequately 

reflect the state of the world, nor individual behaviors, under baseline conditions, consistent with 

Essay 73 375 
EPA guidelines for preparing economic analyses. In comment number 2245, Midwest 

Generation, Edison Mission Energy, LLC commented that EPA did not consider fish 

consumption advisories (FCA), which it believes would decrease the value of fish. 

EPA disagrees with these comments. EPA’s method for estimating recreational fishing benefits 

is based on a benefits transfer approach. Benefits transfer, which is an approach to estimating 

benefits in which results from one study are applied to another context for which original data 

cannot be collected, are increasingly applied as a core component of benefit-cost analyses 

conducted by EPA and other government agencies. EPA’s Economic Analysis Guidelines 

(U.S. EPA 2010; DCN 12-5027) consider benefits transfer to be a standard approach. As noted in 

Chapter 7 of the BA, the validity and reliability of benefit transfer depend on a variety of factors, 

including the quality of underlying studies and the fit and validity of the estimated econometric 

models. 

EPA carefully reviewed and vetted all studies included in the meta-analysis prior to including 

them in the meta-data which provided the basis for the benefits transfer. Results of the metaanalysis of the recreational fishing studies appeared in peer reviewed journals (e.g., Johnston et 

al. 2005; DCN 12-5075; Johnston et al. 2006; DCN 12-4862). Therefore, the Agency concludes 

that the meta-analysis approach provides valid estimates for marginal changes in recreational 

catch that are consistent with the economic analysis guidelines and the Agency’s data quality 

requirements for data used in regulatory analysis. The Agency, however, acknowledges that the 

meta-analysis model used in the analysis of recreational fishing benefits of the final 316(b) rule 

provides a reasonable but not perfect match to the context in which values are desired. 

EPA also discusses the difference between what would be calculated for benefit estimates using 

recreational demand models described by EPRI and EPA’s methods. As described in the 

preamble to the final rule, the methodologies used to estimate benefits of the final existing 

facilities rule are largely built on those used to estimate benefits for the remanded Phase II and 

Phase III. The BA provides references to (i) Part A of the Regional Analysis Document for the 

Final Section 316(b) Phase II Rule (U.S. EPA 2004; DCN 12-5021), and (ii) Part A of the 

Regional Benefits Analysis for the Final Section 316(b) Phase III Existing Facilities Rule 

(U.S. EPA 2006; DCN 12-5024) for analyses using similar methodologies. EPA validated 

estimates of recreational benefits based on the meta-analysis of WTP for catching an additional 

fish as part of its benefits assessment of the Phase III regulation. 

Specifically, EPA used regional models of recreational fishing behavior developed for the Phase 

II analysis to estimate benefits from reduced IM&E at potentially regulated Phase III facilities 

for the four coastal regions and the Great Lakes region. Results of the random access utility 

(RUM) models are presented in Chapter B4 through F4 of the Regional Analysis Document 

(U.S. EPA, 2006; DCN 12-5024). In general, EPA found that the RUM-based recreational 

fishing benefits fall within the range of values estimated for a given study region based on the 

meta-model. That the values from the two independent analyses are relatively close corroborates 

the use of meta-analysis in estimating the value of incremental recreational fishing 

improvements. 

EPA notes that RUM models were not available for the Inland region due to the lack of data 

required for model estimation. Primary studies are also more resource intensive. Given a close 

Essay 73 376 
match between the results from both methods, EPA continued using meta-analysis only in 

estimating recreational fishing benefits for the final Phase III regulation, and for the final section 

316(b) regulation for existing facilities. EPA acknowledges that local detail may be lost in a 

national level analysis, but this situation would occur with the use of other methods and models 

due to data limitations. 

The record provides detailed information on a comparison of the methods that supports use of 

the benefit transfer approach EPA used in the analysis of recreational benefits of the final section 

316(b) rule for existing facilities. Specific limitations and uncertainties associated with the 

estimated regression model and the underlying studies are discussed in section A5-3.3e of U.S. 

EPA (2006; DCN 12-5024). Additionally, Chapter 7 of the BA describes the limitations and 

uncertainties inherent in EPA’s analysis of recreational fishing benefits of the final rule. 

EPA understands that the use of recreational demand models is a standard approach to estimating 

welfare changes stemming from increased visitation to recreational sites, but did not estimate 

such benefits for the 316(b) rule for existing facilities. As stated in Chapter A11 of the Section 

316(b) Phase II Final Rule – Regional Studies (U.S. EPA 2004; DCN 12-5021), the benefit to 

anglers from an increase in recreational catch may occur in two ways: (1) an angler may receive 

greater enjoyment from a given fishing trip when catch rates are higher, and thus receive a 

greater value per trip, and (2) anglers may take more fishing trips when catch rates are higher, 

resulting in greater overall value for fishing in the region. As shown by EPA’s 2004 recreational 

benefits analysis, the estimated welfare changes stemming from an enhanced trip value due to 

improvements in catch rates greatly outweigh benefits from an increase in recreational 

participation (see Chapters B4, C4, D4, F4, and G4 in the Phase II report (U.S. EPA, 2004; DCN 

12-5021). 

The number of recreational trips taken by anglers is influenced by many factors, including 

availability of leisure time, income, family obligation, and others. As a result, general changes in 

catch rates do not necessary result in significant changes in the number of trips. If changes in 

catch rates are small, then the change in the number of trips is likely to be negligible. EPA’s 

model of the number of fishing trips per season developed for the Phase II rule shows a positive 

coefficient on the variable denoting the quality of recreational fishing sites (i.e., IVBASE) 

indicating that an increase in catch rate would have a positive effect on the number of fishing 

trips per recreational season. However, the coefficient on this variable is very small compared to 

other variables that influence the number of fishing trip taken per season (e.g., intercept, gender, 

whether an individual owns a boat, etc.). Thus, the slight improvements in recreational catch 

expected under the final rule are unlikely to lead to a significant increase in the number fishing 

trips to the affected sites. 

EPA did not estimate the percent change in recreational catch rates for the final rule. However, 

the Phase II analysis suggested that the expected increase in catch is likely to be small (less than 

5 percent) for most fish species (with the exception of bottom fish and non-targeted catch in the 

Mid-Atlantic region which EPA expects to increase by 22 and 12 percent, respectively). See 

Chapters B4, C4, D4, F4, and G4 in the Phase II report (U.S. EPA, 2004; DCN 12-5021). The 

application of per-fish WTP to estimating recreational fishing benefits of the final 316(b) 

regulation allows estimating welfare changes from enhanced recreational experience due to an 

increase in catch rates, assuming that the number of recreational trips remains constant. Based on 

Essay 73 377 
the results of recreational fishing analysis for the Phase II rule, including participation effects 

would not substantially change the estimated recreational benefits. 

EPA disagrees that its approach for the analysis of benefits does not adequately reflect the state 

of the world or individual behaviors under baseline conditions, consistent with EPA guidelines 

for preparing economic analyses. As a baseline for the analysis of fishing benefits, EPA used 

current mortality from IM&E, and the corresponding current angler catch rates. This reflects 

estimated conditions without the regulation. To estimate the change from these baseline 

conditions resulting from the final rule, for the reasons explained in Chapter 3 of the BA, EPA 

assumed that the controls would eliminate the mortality in proportion to the reduction in 

entrainment, and that the reduced mortality translates into an increase in catch rates (see detailed 

discussion in Chapter 3 of the BA). This estimate reflects an estimate of conditions with the 

regulation. Note that EPA presents this approach in terms of valuing the forgone catch without 

the regulation (benefits of eliminating baseline IM&E losses). See in section 7 of the BA for 

detail. 

EPA disagrees that it did not consider Fish Consumption Advisories (FCAs). First, EPA notes 

that FCAs do not affect catch and release values. According to U.S. FWS data (2006 DCN 12­

5076), approximately 23.3 percent of freshwater anglers release all the fish they catch (“catchand-release” anglers). The catch and release rate is much higher (60 percent) for the most 

commonly caught saltwater species such as sea trout (NOAA NMFS, 2011; p.10 DCN 12-5077). 

EPA notes that the analysis of recreational fishing benefits was conducted at the regional level 

(see Chapter 7 of the BA). Although a FCA may affect the value of fishing at the FCA affected 

sites and visitation patterns in the baseline, the estimated change in anglers’ welfare due to 

increased catch is unlikely to be significantly influenced by the FCA presence in a given region. 

Consistent with the Phase II and Phase III analyses described above, EPA assumed that the 

regional pattern of visitation to fishing sites will not change, but the catch rate would increase 

with increased fish abundance at the sites visited by anglers under the baseline scenario. 

Declining Marginal Utility

In comment number 2200, and others, EPRI and other commenters claim that EPA does not 

account for decreasing marginal utility in the estimate of per-fish value. 

EPA agrees that the marginal value of catching additional fish declines as catch rates increase. 

The Agency, however, disagrees that the per-fish values based on the meta-analysis were applied 

incorrectly, and thus are likely to produce biased benefit estimates. 

The per-fish WTP values predicted by the meta-analysis are based on per-fish values taken from 

a set of valuation studies, many of which were published in peer-reviewed academic journals, 

and all of which have been vetted by EPA to ensure that they use valid economic valuation 

techniques. The original studies reflect willingness-to-pay for catching an additional fish given 

the baseline catch rates. Given the variety of geographic locations and waterbody types included 

in the original studies, EPA concludes that these studies provide a reasonable approximation of 

baseline catch rates at the fishing sites affected by the section 316(b) regulation. 

Essay 73 378 
As noted in Chapter 7 of the BA, the average baseline catch rates for the affected species range 

from 0.2 to 3 fish per trip. The only exception is the average catch rate for panfish (4.7 fish per 

trip) in the Inland and Great Lakes regions. Where both the baseline catch rate and the expected 

changes being considered are relatively small, the marginal per-fish values predicted by the 

meta-analysis are likely to be more accurate because it is not necessary to account for the 

decreasing marginal value of multiple fish that are caught by the same angler. 

Environmental Justice

In comment number 2200, the commenter (EPRI) states that EPA’s assessment of environmental 

justice-related to recreational fishing benefits is very cursory, and does not consider the impact 

of higher electricity prices on low income groups. 

EPA disagrees. EPA did consider the effect of the rule on electricity prices. As shown in Table 

4-5 of the Economic Analysis report, the estimated percent change in electricity prices for 

residential consumers is negligible (0.08 percent). Therefore, this increase did not a warrant 

further examination of the effects of the price increases on sensitive populations. EPA notes that 

this rule does not prevent the adjustment of utility rates for sensitive populations. In addition, 

EPA found that neither low-income nor minority population groups participate to a lower extent, 

in a statistically significant way, in the benefits of the final rule than the general population in 

states with regulated facilities (see Chapter 12 of the EA). 

Essay 73 379 
Essay 74: Nonuse Benefits Analysis Methods

EPA received a number of comments on the use of a study of fish habitat restoration in Rhode 

Island to estimate the potential nonuse benefits of the rule using a benefits transfer approach. The 

study provides estimates of the willingness to pay (WTP) of Rhode Island residents for 

anadromous fish habitat restoration, and EPA used a model variant presented by Zhao et al. 

(2013; DCN 12-5060) for the final rule analysis. This essay responds to comments on this study. 

Limiting the Transfer to Two Regions

In comment number 2391, Riverkeeper states that it is not appropriate to limit the transfer of 

nonuse benefits from the Rhode Island study to only the North Atlantic and Mid-Atlantic regions 

as EPA did in the BA. Riverkeeper commented that EPA needs to locate other studies, transfer 

the Rhode Island study results to the remaining regions, or complete and apply its own stated 

preference study to estimate nonuse benefits in other regions. Riverkeeper faults EPA’s 

conclusion that only the Rhode Island study is usable for estimating nonuse benefits of reducing 

impingement and entrainment. Riverkeeper cites work on the geographic scope of nonuse values 

by Loomis (2000; DCN 12-4890), proposing that it is appropriate to increase EPA’s nonuse 

values for impingement and entrainment losses in the North Atlantic and Mid-Atlantic regions to 

2.72 times as large as EPA’s estimate to reflect the reduced but non-zero value per household of 

this region’s fish to the rest of the nation. To account for the remaining regions, Riverkeeper 

proposes that, until regionally specific numbers become available, nonuse benefits might be 

roughly proportional to age-one equivalent (A1E) baseline mortality, resulting in an extrapolated 

national total of nonuse benefits of 2.085 times the two-region total. 

EPA disagrees that it is appropriate to transfer the estimates of nonuse benefits based on the 

Rhode Island study beyond the North Atlantic and Mid-Atlantic regions to obtain an 

extrapolated, national, total nonuse benefits estimate. Among the best practices for implementing 

benefits transfer techniques are ensuring the similarity of the resources and population 

characteristics. EPA did not extend the benefit transfer beyond the North Atlantic and MidAtlantic regions because of the potential for substantial differences in species characteristics, 

aquatic resource conditions, preferences, and demographics in other regions compared to the 

original context of the transfer study. For example, the Rhode Island study focused on regional 

environmental issues, notably, the inability of fish to migrate upstream for spawning due to 

dams. The fish specifically mentioned in the study, anadromous alewife, shad, American eel, and 

Atlantic salmon, are not lost to impingement and entrainment in the South Atlantic, Gulf of 

Mexico, or Inland regions. Losses of anadromous fish in the California region occur at facilities 

that will have closed-cycle cooling based on State regulations. Although there may be inferences 

that can be drawn more widely from the study results regarding national nonuse values 

associated with aquatic resources, EPA does not consider the study results to be nationally 

representative. 

As noted in the Information Collection Request (ICR) supporting statement for its stated 

preference study (U.S. EPA, 2012; DCN 12-5033), EPA has not identified any previous studies 

that would provide a good match for the final rule. The ICR indicates that, although there are 

Essay 74 380 
many studies in the environmental economics literature that quantify WTP associated with 

various types of water quality and aquatic habitat changes, none of these studies allows the 

isolation of non-market WTP associated with quantified reductions in fish losses (or increases in 

fish populations) for forage fish. Most available studies estimate WTP for broader, and 

sometimes ambiguously defined, policies that simultaneously influence many different aspects of 

aquatic environmental quality and ecosystem services, but for which WTP associated with fish or 

aquatic life alone cannot be identified. Among available studies, the most closely related is the 

Rhode Island study, which provides estimates of total WTP for multi-attribute aquatic ecosystem 

changes related to improvements in small migratory (diadromous) fish. For a more detailed 

description of available study examples, see section 3(a) on non-duplication of the 316(b) ICR 

supporting statement. 

EPA agrees that the work by Loomis (2000; DCN 12-4890) suggests that households outside of 

the North Atlantic and Mid-Atlantic Regions are likely to have nonuse values for reductions in 

impingement mortality and entrainment under the final rule. However, the percent of households 

affected, and the effect on WTP by distance from specific sites, varies greatly by species. The 

species addressed in the Loomis study (2000; DCN 12-4890) (e.g., salmon, Mexican Spotted 

Owl) are not similar to those affected by the final rule (the majority of which are forage fish), 

and the Rhode Island study did not address WTP for households outside of the state. Therefore, 

EPA does not use this study to support a benefits transfer of the Rhode Island study results to 

households beyond the two regions that it deems similar to the original study area. 

EPA agrees with the commenter that estimating national-level nonuse benefits would improve 

the analysis of benefits for the final section 316(b) existing facilities regulation. As stated in the 

preamble to the final rule, and described in the BA accompanying the proposed and final rules, 

EPA conducted a stated preference survey to calculate benefits associated with minimizing 

adverse environmental impacts to aquatic ecosystems from cooling water intakes. EPA expects 

to seek Science Advisory Board (SAB) review of its survey prior to using the results in benefits 

analyses of national rulemakings. Although it will delay use of the results, EPA considers SAB 

review to be essential given the importance of this issue for the evaluation of ecological benefits 

generally. 

Criticism of the Rhode Island Stated Preference Study

In comment numbers 2210, 2200, 2156, and others, the Utility Water Act Group (UWAG), 

Electric Power Research Institute (EPRI), Edison Electric Institute (EEI), and some power 

generating facilities argue that limitations inherent in the stated preference approach generally, 

and the Rhode Island study specifically, render the results nontransferrable. Commenters assert 

that the Rhode Island stated preference study creates preferences through formulation of the 

ecological indicators presented to respondents; is subject to potential bias related to inherent 

double-counting in the underlying attributes respondents are valuing, and potential hypothetical 

bias. Commenters also assert that pre-testing does not ensure the elimination of biases, and a 

study by Murphy et al. (2005; DCN 12-5078), who conduct a metastudy of studies that compared 

actual and stated WTP, and an empirical analysis relating the amount of overstatement bias in 

stated WTP to various features of the study, suggests an overstatement of WTP in the Rhode 

Island study. 

Essay 74 381 
EPA disagrees with these comments. The published literature supports the use of the stated 

preference approach generally for nonmarket valuation or estimating nonuse benefits, and for use 

in benefit-cost analysis (e.g., Freeman, 2003; DCN 12-4815; Boardman et al., 2006; DCN 12­

5066). Although EPA recognizes that controversy exists over the use of stated preference 

methods, by definition, market-based information does not exist for valuing nonmarket goods 

and services. Nonuse values can only be estimated by extracting information on preferences. 

Carefully constructed stated preference surveys represent one means of obtaining this 

information. 

The “creation of preferences” claim has been a common argument of stated preference skeptics 

for over two decades, but has not been found to be a convincing argument against the use of the 

method, including in the National Oceanic and Atmospheric Administration (NOAA) Blue 

Ribbon Panel (Arrow et al. 1993; DCN 12-4730). Moreover, the Rhode Island study in question 

has been published in the peer reviewed literature on multiple occasions as an example of how to 

improve stated preference valuation of aquatic ecological changes. More specifically, it has been 

cited as an example of the improved use of ecological indicators within stated preference 

surveys, and the appropriate design of such surveys to value aquatic ecological changes (e.g., 

Johnston et al., 2011a, 2011b, 2012, and 2013; DCNs 12-4864, 12-4866, 12-4865, and 12-5079; 

Schultz et al., 2012; DCN 12-5080; Zhao et al., 2013; DCN 12-5060). Counter to the claim that 

there is “potential bias” related to the use of ecological indicators in this study, the scientific 

literature has repeatedly published this work as an example of how researchers should construct 

SP surveys for valuation of aquatic ecological changes, including the use of ecological reference 

conditions to help respondents comprehend the scope of ecological change (Johnston et al., 

2012; DCN 12-4865). 

EPA emphasizes that all aspects of the Rhode Island stated preference survey were developed 

based on extensive focus group and interview testing to evaluate outcomes that were relevant to 

respondents’ welfare, and effective methods of communicating these attributes (Johnston et al. 

2011a, 2011b, 2012, and 2013; DCNs 12-4864, 12-4866, 12-4865, and 12-5079; Schultz et al., 

2012; DCN 12-5080; Zhao et al., 2013; DCN 12-5060). As detailed in these peer reviewed 

articles, the study included multiple focus groups and cognitive interviews to determine, among 

other things, the type and quantity of information that the respondents required in order to make 

an informed, comfortable decision, as recommended by Bateman et al. (2002; DCN 12-4740) 

and many others (e.g., Arrow et al., 1993; DCN 12-4730; Mitchell and Carson, 1989; DCN 12­

4909). The authors used these focus group and interview results to determine the type and 

quantity of information provided in the survey, including the communication of ecological 

attributes. 

Regarding potential bias related to inherent double-counting in the underlying attributes, the 

commenter does not provide evidence to support the claim. The Rhode Island study was 

explicitly designed to mitigate any potential for double-counting in the valuation of aquatic 

ecological changes. This issue is addressed explicitly in Johnston et al. (e.g., 2011a and 2013; 

DCNs 12-4864 and 12-5079), who demonstrate both theoretically and empirically that the 

inclusion of the aquatic ecological condition index does not double-count welfare gains from 

aquatic ecological improvements. The authors also demonstrate that inclusion of this indicator is 

necessary (in this case study) to prevent respondent speculation and bias that could lead to 

embedded values being inadvertently double-counted in analysis. 

Essay 74 382 
Regarding potential hypothetical bias, as noted in the above cited peer reviewed publications, the 

Rhode Island stated preference questionnaire was developed based on more than two and a half 

years of testing, in a collaborative process that included participation of economists, ecologists, 

resource managers, natural scientists, and members of stakeholder groups. The study included 12 

focus groups with Rhode Island residents. These pretests included verbal protocols (Schkade and 

Payne, 1994; DCN 12-4978) to assess how respondents understood and answered choice 

questions. Among the goals of this survey design process, which was much more extensive than 

that found in the majority of studies in the peer reviewed literature, was the amelioration of 

potential hypothetical bias. 

Moreover, this comment provides no specific theoretical or empirical evidence that hypothetical 

bias is prevalent in the transferred estimates of WTP, beyond ad hoc claims regarding the amount 

of information provided to respondents and the familiarity of respondents with the policy 

context. Both of these issues are addressed explicitly and extensively in the papers published 

from this research study (Johnston et al. 2011a, 2011b, 2012, and 2013; DCNs 12-4864, 12­

4866, 12-4865, and 12-5079; Schultz et al., 2012; DCN 12-5080; Zhao et al., 2013; DCN 12­

5060). 

Regarding potential bias due to the failure to remind respondents of substitutes and alternatives, 

the comment is based on incorrect information. The Rhode Island survey reminded respondents 

both of substitutes and alternatives at the local level (including a map showing all rivers in 

Rhode Island that provide passage for migratory fish, as well as all other rivers in which fish 

passage could be restored) as well as the national level (e.g., public safety, homeland security, 

economic improvement and jobs). 

Regarding tests of internal validity, the comment is based on incorrect and misleading 

information. The Rhode Island study involved a variety of tests of internal validity. The 

comment incorrectly claims, for example, that alternative surveys were not administered. As 

reported by various peer reviewed publications (Johnston et al. 2011a, 2011b, 2012, and 2013; 

DCNs 12-4864, 12-4866, 12-4865, and 12-5079; Schultz et al., 2012; DCN 12-5080; Zhao et al., 

2013; DCN 12-5060), the Rhode Island study authors developed multiple versions of the survey, 

enabling multiple tests of sensitivity and internal validity. None of these tests suggested a lack of 

validity. 

EPA agrees that pretesting cannot guarantee that all biases are eliminated. However, there is 

overwhelming consensus in the literature that biases can be greatly reduced, and in some cases 

eliminated, by proper and extensive development and pretesting (cf. Mitchell and Carson 1989; 

DCN 2-4909; Bateman et al., 2002; DCN 12-4740; Arrow et al., 1993; DCN 12-4730). As noted 

above, the Rhode Island survey was subject to more extensive development and pretesting than 

the great majority of studies found in the peer reviewed literature, and has been the basis for 

multiple publications on improved stated preference methods. This comment provides no 

empirical or theoretical evidence of bias in EPA’s benefit transfers, only the general claim that 

pretesting cannot always guarantee that biases are eliminated. 

EPA disagrees with the comment regarding a study by Murphy et al. (2005; DCN 12-5078) that 

applying “Model 2B” yields an overstatement of WTP of over 100 percent. This comment is 

based on a misuse of the meta-analysis of Murphy et al. (2005; DCN 12-5078), resulting in 

Essay 74 383 
misleading and biased inferences regarding hypothetical bias. First, the meta-analysis is 

misapplied, based on a misinterpretation of the variables in the model. For example, the 

hypothetical value variable (lnHypValue) in the meta-analysis of Murphy et al. (2005; DCN 12­

5078) is the WTP value directly stated by respondents (or directly inferred from choice 

responses) in the original study. For a study with an annual payment vehicle, this would reflect 

the stated annual WTP. The commenter’s interpretation of the direct WTP from the Rhode Island 

study (Johnston et al. 2011; DCN 12-4864) for this comparison (as payable forever, at a 25 

percent discount rate) artificially and improperly inflates the original hypothetical WTP estimate, 

and as a result generates a misleadingly high estimate of the projected difference between stated 

and actual WTP. Hence, this comment misinterprets the variable definitions of Murphy et al. 

(2005; DCN 12-5078). 

Second, and perhaps more importantly, Murphy et al. (2005; DCN 12-5078) did not intend the 

meta-analysis to be used in this manner; that is, to project an estimate of hypothetical bias for 

studies that were not in the original metadata. In fact, Murphy et al. (2005; DCN 12-5078) are 

very careful to indicate the severe limitations of their results. For example, as stated on pages 

322-323, “We are reluctant to over-emphasize the significance of the dummy variables because a 

meta-analysis of hypothetical bias appears to be very sensitive to model specification, a lack of 

variability in the data, and treatment of extreme values. In addition, some of our key findings 

differ from those reported in previous research...This means that our ability to determine the 

factors responsible for this bias is quite limited, and that estimates of statistical significance 

associated with several potentially important determinants of bias should be viewed with 

caution.” 

For both of these reasons, the Agency has determined that the estimate of hypothetical bias 

provided in this comment does not provides useful information regarding the presence or extent 

of possible hypothetical bias in the Rhode Island study. 

EPA’s Application of the Rhode Island Study

Commenters critical of EPA’s use of the Rhode Island study to estimate nonuse values for the 

316(b) existing facilities rule claim that EPA fails to explain how the study correlates to the rule, 

or account for site-specific differences in the types of species being impinged and entrained. 

UWAG states that a number of the assumptions required to conduct the benefits transfer may be 

invalid, including that Rhode Island ecological indicators may not be representative of the entire 

North Atlantic and Mid-Atlantic Regions; that the Rhode Island baseline is different than the 

baselines in the whole North Atlantic and Mid-Atlantic Regions; and that stated WTP is unlikely 

to be linear in the percentage of the maximum possible number of fish that the policy would 

restore. UWAG concludes that it is not appropriate to use the Rhode Island survey to calculate 

national nonuse benefits or for permit writers to use this survey in site-specific determinations of 

potential nonuse benefits from forage fish gains. 

EPA disagrees with these comments. EPA acknowledges that no study represents a perfect match 

to the 316(b) existing facilities rulemaking alternatives, including specific baseline resource 

conditions (except for EPA’s stated preference survey). However, benefits transfer is an accepted 

practice for estimating environmental benefits when similar studies are available. EPA fully 

describes the study and the parallels to the rulemaking in the benefits analysis accompanying the 

Essay 74 384 
proposed and final rules. Specifically, EPA points out that, “The choice experiment addresses 

forage species such as alewife and blueback herring that neither are subject to current 

recreational or commercial harvest in Rhode Island nor are charismatic species. Hence, the 

species affected are a close analog to the forage fish affected in the 316(b) policy context. 

Moreover, the policy context of the Rhode Island study involves changes to technologies used 

within in-water structures (i.e., the use of fish ladders or fish lifts at dams), providing another 

parallel to the 316(b) context, which also involves the use of new technologies within in-water 

structures to mitigate harm to aquatic organisms.” 

EPA also provided analysis specific to the issues of scope noted by the commenter. As discussed 

in the benefits analysis, within the choice scenarios of the Rhode Island study each ecological 

attribute is expressed in relative terms with regard to upper and lower reference conditions (i.e., 

best and worst possible in the Pawtuxet) as defined in survey informational materials. Relative 

scores represent percent progress towards the upper reference condition (100 percent), starting 

from the lower reference condition (0 percent). This also implies bounds on the potential 

attribute levels that might occur in the choice questions, following guidance in the literature to 

provide visible choice sets (Bateman et al., 2004; DCN 12-4739). The number of fish affected by 

316(b) regulations is many times larger than that considered in the Rhode Island study, such that 

using the per fish values would likely be an overestimate. Therefore, EPA transferred the results 

based on percentage improvements in the fish condition, relative to the reference condition for 

each ecosystem, to address the scale concern described above. 

EPA also addressed these issues in the uncertainty section of the BA. Although some 

uncertainties would result in overstatement of benefits, others are likely to understate benefits. 

EPA disagrees that site-specific differences precludes the use of the study to estimate potential 

benefits for these two regions as a whole. EPA defined its study regions based on similarities of 

species affected by impingement and entrainment, and fisheries regions defined by NOAA. 

NOAA’s delineation of fisheries regions is based on similarities of fish species and 

characteristics of commercial and recreational fishing activities in the areas. For example, the 

habitat range for many pelagic species (including shad, herring, striped bass) spans from North 

Carolina or Virginia to Maine. Therefore, EPA transferred the results of the Rhode Island study 

to both the North Atlantic and Mid-Atlantic regions. The North Atlantic region includes all 

estuary, tidal river and ocean facilities in Maine, New Hampshire, Massachusetts, Connecticut, 

and Rhode Island. The Mid-Atlantic region includes all estuary, tidal river and ocean facilities in 

New York, New Jersey, Pennsylvania, Maryland, the District of Columbia, Delaware, and 

Virginia. 

Indeed, as discussed above, other commenters strongly suggest extrapolating the study beyond 

the North Atlantic and Mid-Atlantic Regions. Although EPA did not use the Rhode Island survey 

to calculate national level nonuse benefits (for reasons described above), EPA disagrees that the 

study is not appropriate for site-specific determinations of potential nonuse benefits when there 

is a close match between the resource and populations characteristics. 

Essay 74 385 
Essay 75: Nonuse Benefits on Reducing I&E Mortality: Habitat‐based

Approach

EPA received a number of comments on the habitat-based methods for estimating nonuse values 

of reducing fish losses at cooling water intakes. 

Role of Habitat‐Based Approach Results

EPA received conflicting comments on the role of the habitat-based approach results in the 

analysis of benefits of the section 316(b) final rule. In comment number 2391, Riverkeeper states 

that use of nonuse values calculated with the “habitat restoration area equivalent” method would 

close the entire gap between estimated costs and benefits under Option 1, or about half the gap 

under Options 2 and 3 in the proposed rule, yet EPA does not include it in its best estimate of 

costs and benefits. In comment number 2210, the Utility Water Act Group (UWAG) asserts that 

EPA should not use the habitat-based method indirectly as a justification for the national 

impingement rule, or to provide estimates in site-specific determinations, because it is based on a 

large number of assumptions. UWAG notes that use of such a method in oil spill damage 

assessments is for developing estimates of the relative similarities of lost and gained habitats, not 

for estimating dollar values for fish protection. In comment number 2200, the Electric Power 

Research Institute (EPRI) claims that it is not clear how the estimates fit into the proposed rule 

benefit analysis or to what extent they are to be used as part of the record to determine that the 

rule will produce benefits that justify the costs of the rule. UWAG also claims that the estimates 

EPA develops do not distinguish between use and nonuse benefits. As such, it would not be 

desirable to replace all of the other careful analyses with the habitat-based results as EPA would 

need to do without being able to distinguish between use and nonuse benefits. 

Assumptions in the Habitat‐Based Approach

In comment numbers 2210 and 2200, UWAG and EPRI comment on the assumptions underlying 

the habitat-based method results. UWAG terms EPA’s numerous assumptions unrealistic, 

including: that all fish species are aggregated in the calculations; a single habitat (e.g., eelgrass) 

is assumed to be relevant within a region; willingness to pay (WTP) values for habitat restoration 

were based upon stated preference studies; WTP for habitat restoration can be converted to 

meaningful estimates of WTP for fish habitat; a single study (from salt marsh restoration in 

Narragansett Bay in Rhode Island) was used to estimate the proportion of value associated with 

fish habitat in the Mid-Atlantic, South Atlantic and Gulf of Mexico regions; arbitrary values of 

10, 20, and 100 percent to estimate the proportion of value associated with fish habitat in other 

regions; that the resulting per acre value was associated with nonuse values; and that all residents 

within a state with an affected waterbody would have nonuse values. EPRI claims that there 

appears to be significant differences between the hypothetical choice scenario and policy context. 

EPRI cites the National Oceanic and Atmospheric Administration’s proposed natural resource 

damage assessment (NRDA) regulations list of three basic issues that researchers should consider 

when selecting transfer. In addition, EPRI claims that the populations having knowledge of and 

being affected by changes in impingement mortality and entrainment (IM&E) are likely to be quite 

different from those knowing about and being affected by changes in habitat. 

Essay 75 386 
The Habitat‐Based Method’s Unrealistic Results

In comment number 2210, UWAG terms EPA estimates of nonuse benefits resulting from the 

habitat-based method implausible because the results are more than a factor of 30 larger than 

those developed using other methods, as well as that the results imply each household in the 

Mid-Atlantic region would be willing to pay $89 each year for the fish saved due to the national 

impingement rule, again stating that the method should not supplant careful benefits assessments 

of the potential for significant nonuse benefits in section 316(b) site-specific benefit assessments. 

Response to Comments

Although EPA disagrees with many of the specific comments, the comments are not relevant for 

purposes of the final rule because EPA decided not to employ the habitat-based approach to 

nonuse values in the final rule analysis. EPA included the habitat-based approach at proposal 

because it illustrated the potential magnitude of nonuse values, and provided additional support 

for both the benefits transfer and SP survey approaches to benefit estimation, described in 

Chapters 8 and 11 of the BA. However, EPA did not consider the habitat-based approach 

appropriate for primary analysis of nonuse benefits, and thus did not include habitat-based 

estimates in the total benefits of eliminating or reducing IM&E under the final rule. 

EPA agrees that more information is needed on nonuse benefits in comparing the benefits and 

costs of the rule. EPA considered the monetization of the nonuse benefits from the rule to be 

incomplete. This is why the agency adopted the habitat-based analysis for the proposal while 

working on methods (i.e., a stated preference study) for the final rule to enable it to estimate and 

incorporate such benefits in the benefit-cost comparison. 

EPA disagrees that it is using the habitat-based method as an indirect justification for the 

national impingement rule. EPA chose not to employ the habitat-based approach for estimating 

nonuse values for the final rule or include them in assessing the total benefits of the rule. Thus, 

these estimates and methods are not applicable to EPA’s final decision-making. 

Rather, as explained in the preamble to the final rule, EPA looked at a number of factors, 

consistent with the Courts’ rulings regarding making this determination. EPA first considered the 

availability and feasibility of various technologies, the associated costs (including potential costs 

to facilities and households), and the economic impacts. EPA reviewed the efficacy of these 

technologies in reducing impingement mortality and entrainment. EPA also considered 

additional factors set out in CWA section 304(b), including location, age, size, and type of 

facility. EPA next considered the non-water quality environmental impacts of different 

technologies on energy production and availability, electricity reliability, and potential adverse 

environmental effects that could arise from the use of the different technologies evaluated. 

As a result of this thorough evaluation, EPA is promulgating a rule that includes a best 

technology available standard for impingement mortality based on modified traveling screens 

with a fish handling and return system whose performance has been optimized to minimize IM, 

and several options for compliance. 

EPA cannot rule out at this time that habitat based approaches to benefits analysis may be 

informative for site-specific determinations. 

Essay 75 387 
Essay 76: Break Even Analysis

Introduction

EPA received a number of comments on the estimated break-even comparison of total national 

social benefits to total national social costs. (The break-even approach enables EPA to work 

backwards to estimate what the non-monetized values would need to be, in terms of willingnessto-pay, per household, per year, in order for total annualized benefits to equal annualized costs.) 

This essay responds to those comments. 

At the outset, EPA emphasizes that section 316(b) does not require impingement mortality and/ 

or entrainment controls to be justified by an exact balance of costs and benefits. See Entergy 

Corporation v. Riverkeeper, 556 U.S. 208 (2009) (permitting, but not requiring, cost-benefit 

analysis). Instead, the reasons for the requirements are discussed in the rule. EPA understands 

that Executive Order (EO) 13563 requires that costs of a rule be justified by the benefits, but this 

same EO recognizes that some benefits are difficult to quantify. Values that the public holds for 

ecosystems are difficult to quantify and, as the guidance for implementing EO 13563 states, do 

not take into account equity and fairness. 

These issues of equity and fairness are relevant when dealing with externalities, such as one 

entity harming a public good such as a fishery or recreational water. In its analysis, EPA attempts 

to monetize benefits, and where monetizing benefits is not possible, to quantify benefits. Where 

EPA is not able to quantify benefits, EPA attempts to describe benefits. However, EPA’s 

conclusion under EO 13563 that the benefits of the rule justify the costs is not based on a simple 

comparison of monetized benefits and total costs. Instead, EPA incorporates the non-monetized, 

nonuse benefits into its consideration of the benefits of the rule. The comments below take issue 

with that incorporation. EPA’s responses to those critiques then follow. 

Riverkeeper Comments

In comment 2391, Riverkeeper states that EPA’s break-even calculation assumes that only 

households in States with regulated facilities care about the fish affected by these facilities 

(although those State encompass almost all of the population), and criticizes EPA’s use of 2000 

Census data on the number of households. Riverkeeper claimed that using more recent Census 

data would lower the break-even estimate. 

EPA agrees with this comment and used 2010 Census data on the number of households in its 

analysis for the final rule. EPA concurs that although including the States in which affected 

facilities are located encompasses most of the population, households in the omitted States of 

Idaho and Nevada, and the District of Columbia are also likely to hold nonuse values for fish 

affected by the final rule. Including those additional States and the District of Columbia added 

1.9 million households to the 114.9 million households EPA used in the analysis for the final 

rule. 

Riverkeeper performs a break-even calculation with its own estimates of omitted benefits. 

However, Riverkeeper suggests that the estimates of the per household gap between total costs 

Essay 76 388 
                                                            

and monetized use-value benefits in EPA’s original analysis could be used to describe the 

benefits of not killing large numbers of fish, shellfish, etc. and asking whether people are willing 

to pay the indicated amount in higher electricity bills. Riverkeeper states that this provides what 

might be called a “holistic” comparison of costs and benefits, citing Ackerman and Heinzerling 

(2004; DCN 12-5065). Riverkeeper stated that this would be a more meaningful and accessible 

approach than a complex academic analysis of the inference of what individuals must be willing 

to pay; instead, it involves asking them directly, with the question tailored to this decision in 

particular. 

EPA disagrees with the commenter’s approach to using the break-even results. The results are 

not appropriate for use in survey design, but rather, for comparison to other study results. One 

such study is EPA’s own stated preference survey, which used electricity bills as a payment 

vehicle to estimate the public’s total willingness-to-pay (use plus nonuse value) to avoid fish 

losses, following standard practices for survey design and value elicitation. This method involves 

directly asking people the question tailored to this decision in particular. Focus groups indicated 

that individuals are willing to pay an amount in the range of the break-even result which EPA 

calculated. 

UWAG Comments

In comment 2210, the Utility Water Action Group (UWAG) compares the break-even value to 

estimated use values, and finds the result (the number of times that the break-even value exceeds 

the use value) to be implausible. UWAG calls EPA’s conversion of the gap in estimated costs 

and benefits into a dollar value per household misleading because per household break-even 

values would be only about 4 percent higher for an option that costs as much, but has only 1/10th 

the impact on fish mortality based on use benefits that UWAG estimates by dividing EPA’s 

estimate by 10. Also, UWAG states that EPA could make the cost look even smaller by using the 

number of individuals rather than the number of households, or all the households in the world. 

UWAG states that the flawed reasoning based on a “break-even” analysis resembles the use of 

“habitat replacement costs” to represent the “value” of fish in the Phase II rulemaking. 

EPA disagrees with these comments. Regarding the comparison of the break-even value to use 

values, there is no a priori evidence to suggest that the ratio is implausible, and UWAG offers 

none. EPA notes that a very large number of users59 plus nonusers holding even relatively low 

nonuse values, compared to a relatively small number of users holding use values – even if use 

values are higher than nonuse values for users – could still result in a total nonuse value that 

exceeds the total use value. Even if both costs and monetized benefits are reasonably accurately 

measured, it is not implausible for the public to hold high values for avoiding resource loss, and 

these values may increase the greater are the losses this regulation is designed to reduce. 

EPA estimated use benefits on a per household basis, and it is appropriate to judge nonuse values 

on a per household basis as well. WTP values in the literature are typically reported on a per 

household basis because the household is the fundamental consumer decision-making unit (many 

households include members who are not independent consumers or economic agents). For this 

reason, EPA disagrees that the number of individuals rather than the number of households is the 

appropriate unit for comparison. EPA further notes that the comment is moot because EPA did 

59 Users clearly hold use values, but users may also hold nonuse values. 

Essay 76 389 
not use the overall population in its break-even analysis. EPA disagrees with the commenter’s 

hypothetical analysis; the comment is not relevant because such an option was not available to 

EPA, and the commenter has no basis for speculating that EPA would have selected an option 

that costs the same but is 1/10th as effective. EPA agrees with the commenter foreigners may 

hold nonuse values for U.S. resources. However, EPA does not include their nonuse values in 

benefits analyses because the Agency is comfortable making the determination that total benefits 

justify total costs on the basis of the U.S. population alone. Incorporating values held by 

foreigners would simply make a stronger case for the same determination. 

Finally, EPA disagrees that the break-even analysis and habitat replacement cost analysis 

represent flawed reasoning. Rather, EPA recognizes that it is flawed to compare total costs to 

partial benefits, and provides these approaches to shed as much light on the cost-benefit results 

as possible in the absence of complete information on society’s values. 

Essay 76 390 
Essay 77: 316(b) Stated Preference Survey

EPA received a large number of comments on the proposed rule and NODA addressing the use 

of stated preference (SP) surveys to determine benefits associated with the rule. EPA conducted 

a SP survey to calculate benefits associated with minimizing adverse impacts to aquatic 

ecosystems from cooling water intakes. 

For some commenters, the use of SP surveys to evaluate benefits remains controversial, and they 

objected to using such surveys. Other commenters acknowledge the decades of technical 

development and improvement of these methods and support using SP surveys. In part to address 

the issues surrounding the use of SP surveys, as discussed in Chapter 11 of the Benefits Analysis 

document, EPA plans to obtain Science Advisory Board (SAB) review of its SP survey. 

The upcoming SAB review is in addition to the external peer review EPA already conducted on 

the survey. SAB review will provide another high-caliber, independent professional judgment 

concerning the quality of the survey, including possible improvements EPA could make to the 

analysis. EPA also plans to seek SAB input on whether, how, and in what circumstances this or 

similar surveys could be used as support for other national rulemakings or for 316(b) NPDES 

permits. EPA expects that this SAB review will delay when EPA considers the survey results 

appropriate for use in supporting a rulemaking or a permit proceeding. Given the importance of 

answering the outstanding questions about use of the survey for the evaluation of ecological 

benefits, however, EPA has concluded that this additional time and effort is justified. Given the 

contemplated SAB review, using the SP survey results prior to completion of review would be 

premature. EPA notes that the survey was designed to estimate respondents’ willingness to pay 

for changes in the health of fish populations and aquatic ecosystems and be statistically 

representative at large (regional and national) scales; the results were not designed to be 

statistically representative at the facility level for the assessment of benefits for individual sitelevel permitting decisions. That the survey was not designed for site-specific permitting does not 

necessarily mean that it cannot be adapted for such use. At this time, EPA has not attempted such 

an adaptation, although it may do so in the future. Regardless, EPA is committed to working 

with the States to support their 316(b) site-specific permitting decisions with the benefit of the 

SAB review once it is completed. 

This essay summarizes key comments received by EPA, both critical and supportive of the SP 

survey, and provides EPA’s response to these comments. In many instances, the comments are 

moot, given that EPA did not rely on the results of the stated preference survey for the final rule. 

These comments are divided into two categories: (1) nonuse values, and (2) use of the SP survey 

results for cost-benefit analysis. 

The commenters also reference numerous comments on EPA’s earlier Information Collection 

Requests (ICR) from 2005 to 2011, asserting that these comments are still relevant. EPA 

provided detailed responses to all ICR comments submitted under previous 316(b) rulemakings, 

which can be found in the following EPA dockets: W-00-03: Phase I rule proposal;EPA-HQOW-2002-0052: Amendment to Phase I Final Rule; W-00-32: Phase II rule proposal; EPA-HQOW-2002-0049: Phase II NODA and Final Rule; EPA-HQ-OW-2003-0005: Phase III Detailed 

Essay 77 391 
Industry Questionnaire; EPA-HQ-OW-2004-0002: Phase III proposal; EPA-HQ-OW-2004-0020: 

Phase III stated preference survey focus groups ICR; EPA-HQ-OW-2004-0027: Phase I ICR 

renewal; EPA-HQ-OW-2005-0006: Phase III stated preference survey ICR; EPA-HQ-OW-2007­

0142: Phase II ICR renewal; EPA-HQ-OW-2008-0667: Existing Facilities rule; EPA-HQ-OW2008-0719: Phase I ICR renewal; and EPA-HQ-OW-2010-0595: Stated Preference Survey. 

Nonuse Values

Potential for nonuse values—existence of nonuse values for marginal effects on fish stocks—is 

highly subjective and the use of these in support of this rulemaking is inconsistent with EPA’s 

previous approaches. The SP survey and assessment of nonuse values is inappropriate because 

the resources are not unique or limited and the impacts are not substantial or irreversible. The 

necessary conditions for the presence of significant nonuse values have not been met. A 

misunderstanding of the restoration probability is likely to result in the overstatement of nonuse 

values. 

Response: There are no theoretical, necessary conditions for the existence of nonuse values. For 

example, resources do not have to be unique to be the source of nonuse willingness to pay 

(WTP). While factors such as uniqueness can affect the magnitude of willingness to pay, the 

significance of nonuse values depends on individual responses to given conditions. While the 

EPA recognizes the possibility of low nonuse values in this case, significant nonuse values are 

also a strong possibility. In addition, prior research demonstrates public willingness to pay for 

types of resource improvements that are similar to those addressed here (e.g., DCNs 12-4865; 

12-4866). 

EPA notes that participants in focus groups and one-on-one cognitive interviews cited a variety 

of motivations for preventing fish losses, including the satisfaction of knowing that fish exist, the 

desire to bequeath healthy fish populations to future generations, and the desire to protect the 

functioning of aquatic ecosystems. Debriefing questions in the survey instrument verified these 

motivations. EPA is aware of no research—empirical or otherwise—that demonstrates that 

individuals ascribe limited or no value to the aquatic resources affected by the 316(b) regulation. 

EPA agrees that nonuse values are inherently subjective, as are use values revealed through 

behavior, which is why it is important to conduct a public survey to elicit those values. Once 

survey data was collected, EPA conducted a transparent analysis with the goal of reporting 

objective, nationally representative results. The EPA further notes that the referendum format of 

the survey allowed respondents who do not attach nonuse values to fish to choose policy options 

that reflect their preferences; respondents need not value the existence of fish, nor do they need 

to be able to separate their use and nonuse values to respond to the survey questionnaire. EPA 

emphasizes that these comments reflect an assumption, unsupported by data, that nonuse values 

are trivial in this case. The stated preference survey and resulting data provide a direct means to 

test this assumption and evaluate its accuracy. 

Use for Cost‐Benefit Analysis

The survey captures benefits which were previously “zeroed out”—the vast majority of benefits 

(98 percent) have been routinely “zeroed out” or ignored by EPA and State agencies, and this has 

skewed decision-making against environmental protection. Benefits now clearly outweigh costs, 

Essay 77 392 
even while the survey estimates are undervaluing benefits. The SP study confirms what EPA has 

known all along, that benefits of closed-cycle cooling are significant and certainly are not wholly 

disproportionate to its costs. 

Response: It is true that only a small portion of the benefits, particularly the nonuse benefits, 

associated with the 316(b) regulation were quantified in the Environmental and Economic 

Benefits Assessment (EEBA) for the proposed rule. EPA followed a similar analytical approach 

for the final rule, adding new analyses of the benefits of reduced carbon emissions and some 

nonuse benefits estimated via benefits transfer. However, EPA disagrees that the nonmonetized 

benefits were “zeroed out” or ignored. While EPA has not relied on the results of the stated 

preference survey, it is not clear that even if the Agency had that the net benefits of requiring 

closed-cycle cooling would exceed the net benefits of the final rule because of the significance of 

the social cost of carbon. The social cost of carbon is a positive benefit for the final rule, but a 

negative benefit for Proposal Option 2. 

Survey results are invalid and should not be used for cost-benefit analysis—the unprecedented 

application of SP methodology would have broad and long-term negative implications. Using a 

benefits calculation method based on public opinion survey would directly and materially 

jeopardize prospects for a reasonable final EPA rule and subsequent site-specific compliance 

decisions. EPA should rely on traditional methodologies that are based on biological science and 

economic principles, and not on a survey methodology premised on hypothetical scenarios and 

questions. 

Various deficiencies prevent the SP survey from accurately estimating benefits, which is critical 

to the rulemaking process. EPA and other agencies rarely use SP surveys to monetize nonuse 

environmental benefits, and have not previously done so in a national rulemaking covering 

multiple species without the risk of endangerment. EPA’s limited experience in this complicated 

area of experimental economics has not given EPA sufficient opportunity to fully assess SP 

methods. 

Response: Although EPA is not relying on the results of the stated preference survey, EPA 

disagrees strongly with the basic premise of these comments. It is well-documented that there are 

difficulties associated with measuring and monetizing all categories of benefits. While using 

benefit-cost analysis can be illuminating and useful in producing better decision-making, it can 

also be subverted to produce skewed outcomes that allocate resources in a manner contrary to the 

best interests of society at large. This can occur, in particular, through blind reliance on only 

those benefits that can be monetized using traditional approaches, especially when that results in 

an incomplete analysis. EPA notes the significant overlap of the commenters who suggest that 

benefit-cost analysis should be mandatory in decision-making, and those who suggest that stated 

preference methods are too controversial to be used. EPA notes that some of these same 

commenters have a self-interest that appears to be at odds with putting better and more 

illuminating analyses in front of decision makers. Rarely do these comments offer constructive 

suggestions that would rationalize their support for benefit-cost analysis in decision-making with 

improving such analyses to make them more useful in societal decision-making. 

EPA recognizes that there is some controversy over the use of stated preference valuation 

methods. A recent evaluation of this controversy, by Kling et al. (DCN 12-5084. p. 23), however, 

Essay 77 393 
concludes that “the last 20 years of research have shown that some carefully constructed number 

based on stated preference analysis is now likely to be more useful than no number [for] cost– 

benefit analysis.” Stated preference methods have also “been tested and validated through years 

of research and are widely accepted by Federal, State, and local government agencies and the 

U.S. courts as reliable techniques for estimating nonmarket values” (DCN 12-4747, p. 26; DCN 

12-5027). The Agency has concluded that the expansive stated preference and choice experiment 

literature demonstrate that a properly design survey may provide a useful tool for evaluating 

WTP for resources impacted by CWIS. The Agency recognizes the commenter’s perspectives on 

the validity of stated preference methods. The EPA, however, notes the absence of any clear 

consensus in the academic literature that indicates that the survey results are necessarily invalid 

or their use inappropriate as one of a number of tools in decision-making. These methods have 

now been applied in numerous cases to value nonmarket environmental resources and related 

policy changes. The Agency is aware of no theoretical distinction between national policy 

analysis and other policy contexts (including damage assessments) that would render stated 

preference methods unsuitable for such applications. Official guidance documents (DCNs 12­

5027; 12-5027) and the Blue Ribbon Panel (DCN 12-4730)—while explicitly recognizing the 

controversies and challenges—all consider stated preference methods, when conducted using 

best practices, to be a valid source of information. 

As discussed earlier in this essay, EPA decided not to employ the survey results for purposes of 

decision-making in this rule, or include them in assessing the total benefits of the rule. EPA plans 

to continue review of the survey by submitting it to EPA’s SAB. SAB review will provide 

independent professional judgment concerning the quality of the survey, including improvements 

EPA could make to the analysis, and how and in what circumstances this or similar surveys 

could be used, as support for national rulemaking or NPDES permitting whenever benefit-cost 

analysis is considered in the decision-making process. 

Essay 77 394 
Essay 78: National Benefits

EPA received a number of comments on the national benefits of the rule, some asserting that 

benefits are underestimated, and some asserting they are overestimated, with detailed arguments 

for both claims. This essay responds to those comments. 

Benefits are Underestimated

In comment 2391, Riverkeeper states that EPA cannot accurately monetize the benefits of saving 

nonmarket fish, other aquatic organisms, and ecosystems. Riverkeeper concludes that until and 

unless EPA corrects its estimates of fish kills and recreational fishing benefits, completes its 

planned willingness to pay study, accounts for the substantial value that people place on 

environmental preservation (even from a distance), and corrects the serious deficiencies in its 

approach to valuing threatened and endangered species, EPA will continue to dramatically 

undervalue the benefits of a uniform national standard based on closed-cycle cooling. The 

commenter asserts that the flaws in EPA’s analysis, both in quantification and monetization of 

the benefits, are sufficiently large that to rely upon it would be arbitrary, capricious and an abuse 

of discretion. 

The commenter also states that EPA should correct its national estimate to account for the 

deficiencies identified in the Stockholm Environment Institute’s (SEI) report, which it provides. 

SEI applies EPA’s habitat-based method for estimating nonuse values, but extrapolates the 

results nationally. SEI also used a benefits transfer method to infer national threatened and 

endangered species benefits and modified EPA’s estimated recreational fishing benefits based on 

the Bay Shore Power Plant study. The commenter states that these basic modifications result in 

benefits estimates that approach or are greater than EPA’s cost estimates for all of the options 

that EPA considered, including for a uniform national standard based on closed-cycle cooling. 

Also, the commenter states that correcting errors in (the costs and) the benefits estimates leads to 

the conclusion that the benefits of the regulation are greater than the costs for every option. 

In comment 2260, the New York State Department of Environmental Conservation (NYSDEC) 

states that the rule will result in an 82 percent decrease in the reduction of annual mortality of 

age-1 equivalent fish over the remanded Phase II Rule, despite covering an estimated 140 

percent additional existing facilities and increasing the required reduction in impingement 

mortality from 80 percent to 88 percent. NYSDEC asserts that, even considering that 

entrainment mortality reductions are not counted, the drop in benefits does not add up, and either 

EPA has substantially underestimated the benefits or the rule is ineffective. 

EPA agrees that the benefits of the final rule are underestimated as presented, but, for the reasons 

stated in the preamble, EPA would not change its final rule even if it had a more complete 

benefits estimate. EPA has also completed its stated preference survey of willingness to pay (see 

Essay 77 for EPA’s response to comments on the stated preference survey). EPA responds to the 

other suggested adjustments to its benefits estimates elsewhere, and disagrees that it relied 

heavily on the monetized benefits estimates. 

Essay 78 395 
As described in the preamble to the final rule, EPA assessed the benefits of the rule in order to 

comply with Executive Orders (EOs) 12866 and 13563. Pursuant to EO 13563, EPA finds that 

the benefits of the BTA requirements in this final rule justify the costs, despite the fact that 

monetized benefits are numerically lower than the social costs. EPA notes that the monetized 

benefits are only a subset of all benefits. In the absence of complete estimates of nonuse benefits, 

EPA estimated partial nonuse benefits for the final rule using the benefits transfer approach from 

proposal. This approach is still a partial estimate because it concerns only two coastal regions 

and because the original study focused on fish population improvements for a few species (river 

herring, shad, American eel, and Atlantic salmon) in one watershed only. Scaling benefit 

estimates to represent multiple watersheds in the Northeast and Mid-Atlantic region may not be 

sufficient to capture true benefits of aquatic habitat improvements over a large geographic scale 

and dozens of species. In addition, the estimated nonuse value of reducing impingement 

mortality and entrainment (IM&E) was based on the expected improvements to population of 

one species (winter flounder) due to the lack of population data on most species affected by 

IM&E. EPA notes that winter flounder accounts for only 0.9 percent of IM&E losses in the 

North and Mid-Atlantic regions and 0.3 percent of the national IM&E losses. Although it not 

appropriate to estimate nonuse values for reducing IM&E for each species and sum them, the 

value of reducing IM&E for multiple species is likely to be greater than the value of preventing 

losses of a single species. With respect to site-specific BTA entrainment determinations, the 

Entergy decision by the Supreme Court allows benefits and costs to be considered in 316(b) 

determinations on a national or site-specific basis, and the final existing facility rule requires the 

Director to consider costs versus benefits in the site-specific determinations. Note that requiring 

that costs and benefits be considered does not mean that such consideration is paramount to the 

consideration of other factors. 

EPA has added the Bay Shore Power Plant mortality study to the studies it used to model 

regional IM&E for the analysis of benefits. As noted above, EPA describes fully in the preamble 

to the final rule that the benefits of the rule justify its costs. Under EO 13563, agencies “must 

take into account benefits and cost, both quantitative and qualitative,” and to the extent permitted 

by law, only promulgate regulations that are based on “a reasoned determination that its benefits 

justify its costs (recognizing that some benefits and costs are difficult to quantify).” In choosing 

among regulatory alternatives, agencies must select “those approaches that maximize net benefits 

(including potential economic, environmental, public health and safety, and other advantages; 

distributive impacts; and equity) to the extent permitted by law,” including when nonmonetized 

benefits are considered). EPA notes that even if the benefits of the rule or other options are 

somewhat underestimated, it would not have selected a uniform national standard based on 

closed-cycle cooling for entrainment controls, because lack of monetized benefits was not part of 

the rationale for rejecting closed-cycle as a national BTA basis. See the final preamble for 

additional information on options selection and the final regulatory requirements. EPA disagrees 

that the commenter’s analysis of a decline in benefits indicates that the rule is ineffective. EPA 

used the same method of calculating IM&E benefits for the final existing facility rule and the 

Phase II rule. The differences in the estimated IM&E reductions are due to changes in input data, 

in particular, data on state regulations and technologies in place under the baseline scenario. 

Since the initial Phase II analysis, State regulations more stringent than the proposed rule have 

been instituted. Therefore, the estimated reduction in IM&E associated with the national rule for 

facilities in these states is zero, as are the costs. 

Essay 78 396 
In addition, several facilities have improved baseline levels of environmental protection, either 

by newly installing technologies that reduce IM&E, or installing improved technologies, 

including the installation of closed-cycle cooling in several locations; see Technical 

Development Document for the Final Section 316(b) Existing Facilities Rule (DCN 12-0003), 

Plant McDonough in Georgia (retrofit in 2008), Canadys Station in South Carolina (retrofit in 

1992), and Nearman Creek in Missouri (retrofit in 2006) for examples of the implementation of 

closed-cycle cooling for reasons of either Clean Water Act Section 316(a) (thermal) or water 

supply/availability concerns. These changes reduce baseline losses, and thus, the overall 

reduction in IM&E that will result from the final rule. 

Finally, EPA has substantially increased the number of model facilities reflected in the benefits 

analysis since the Phase II analysis from 48 for the Phase II rule to 98 for the Final 316(b) 

Existing Facilities Rule to improve its estimates of IM&E. This change affected EPA’s estimates 

of total IM&E losses in several study regions and at the national level. 

Together, these changes explain the reduced national effects of the final rule when compared to 

the Phase II rule. 

Benefits are Overestimated

Other commenters claim that EPA overestimated the benefits of the final rule. In comment 2458, 

AES North America, L.P. refers to the National Benefits of a Closed-Cycle Cooling Retrofit 

Requirement Report finalized by the Electric Power Research Institute (EPRI) in August of 

2011, finding that many of EPRI’s and EPA’s assumptions overstate benefits: assuming 100 

percent mortality for entrainment; not accounting for the ability of fish and other aquatic species 

to compensate for losses of individuals by generating large numbers of eggs; not fully accounting 

for fish that are not likely to survive regardless of I&E; assuming all forage biomass is consumed 

by harvested species; not accounting for water quality benefits of cooling water flow that would 

be lost; and not accounting for facility closures for other reasons. AES further outlines 

assumptions that it states could result in either an over- or underestimate of benefits, such as 

annual variability, constantly changing fishery conditions, and lack of data. 

In comment 2215, Duke Energy Business Services, LLC argues that nonuse benefits are 

independent of any current or anticipated use of the resource, and thus have little connection to 

I&E at affected facilities, claiming it a stretch to include such benefits when costs are limited to 

State and Federal administrative agencies, manufacturers, and electric utilities. 

In comment 2215, Duke Energy Business Services, LLC stated that EPA chose artificially low 

discount rates, thereby increasing the value of benefits. The commenter also provided a 

comparison to personal discount rates of fishermen. 

In comment 2347, Entergy Corporation states that to ensure that potential benefits are real, not 

fictional, the final rule should account for cumulative benefits resulting from use of readily 

installed technologies over technologies with longer installation times. 

In comment 2245, Midwest Generation, Edison Mission Energy, LLC states that EPA’s 

assumption in extrapolating benefits that impingement and entrainment mortality rates recorded 

at model facilities are representative of such rates at other facilities in the region is problematic. 

Essay 78 397 
A variety of reasons were offered, including that site-specific considerations such as debris load 

and the mix of species impinged or entrained can greatly impact the performance of a given 

facility. The commenter finds that EPA does not provide the data, information regarding the data 

or the selection of model facilities, making it difficult to reproduce the data published in the 

Environmental and Economic Benefits Analysis (EEBA) for the proposed rule. The commenter 

states that if the data are biased in any way, the monetized benefits will also be biased. The 

commenter calls for acknowledgement that the rates of I&E losses at some facilities are very 

low, and consideration of alternative measures as well as a site-specific variance provision that 

would be based on locally estimated adverse environmental impacts and cost and benefit 

considerations. 

EPA understands the uncertainties in the benefits analysis regarding the population dynamics of 

aquatic species. EPA supports its analysis of benefits with recent scientific literature. The 

cumulative losses from I&E may also have ecosystem effects that EPA has not identified and 

monetized. EPA disagrees with the comment regarding not accounting for premature facility 

closures due to economic reasons other than closed-cycle cooling retrofits: the analysis of 

benefits is consistent with the assumptions regarding economic viability and installation of 

control technologies reflected in the cost analysis. The benefits analysis measures benefits 

associated with the regulation, and such closures are not caused by the regulation. EPA has taken 

into account the demand for electricity in projecting the benefits of the rule, and if there are 

premature closures, the electricity that would be generated by that facility must be generated by 

another facility. However, as described above and in the preamble to the final rule, EPA 

considered a number of factors not related to benefits and costs in selecting the option for the 

final rule. 

EPA disagrees that nonuse values have little connection to I&E at affected facilities. I&E affects 

the condition of the resource, the existence of which is valued by many regardless of use (i.e., 

nonuse benefits) as demonstrated in focus groups conducted as part of EPA’s stated preference 

survey. Note also that compliance technology costs to manufacturers and utilities may be passed 

on to consumers, and agency costs are borne by taxpayers. 

EPA disagrees that it chose low discount rates. EPA discounted the various categories of benefits 

for comparison to compliance costs, consistent with Office of Management and Budget 

guidance. Such comparisons reflect the time paths for realizing both costs and benefits, and are 

based on a discount rate reflective of society as a whole as opposed to individual members. 

EPA understands the time considerations in realizing benefits. As noted by the commenter, EPA 

developed a time profile for realization of benefits. EPA developed a similar timeline for 

compliance technologies. Thus, cumulative benefits from the use of readily installed 

technologies as well as technologies associated with long installation periods, such as closedcycle cooling, will be reflected appropriately in both benefits and costs. 

EPA disagrees with the comments regarding the information on model facilities or I&E data used 

in the benefits analysis. IM&E data from facilities is in the docket for the rulemaking. EPA 

provides total flow from each region in Chapter 1 of the Benefits Analysis for Final Section 

316(b) Existing Facilities Rule (BA; U.S. EPA, 2014; DCN 12-4500 to DCN 12-4700), which 

allows calculation of average I&E per million gallons per day. The Agency, however, notes that 

Essay 78 398 
the facility input data for the I&E model is treated as Confidential Business Information (CBI) in 

the record because it includes a combination of I&E data and information from the industry 

survey, which is treated as CBI. Chapter 3 of the BA for the final rule describes the use of IM&E 

data from model facilities and extrapolation of these data to develop regional IM&E estimates; 

also, Appendix A of the EEBA (U.S. EPA, 2011; DCN 12-5032) describes the extrapolation 

methods, based on the data noted in the record for the previous rulemakings. 

EPA agrees that site-specific variability in IM&E and expected benefits of the rule exist. EPA 

has incorporated site-specific considerations into the final rule through the flexibility provided in 

the selected options, rather than a site-specific variance provision. As described fully in the 

preamble to the final rule, EPA provides seven alternatives for compliance with the national 

impingement mortality standard at existing facilities. The seventh alternative (at 40 CFR 

125.94(c)(7)) for complying with the BTA impingement mortality standard requires the owner or 

operator to conduct biological compliance monitoring to demonstrate compliance with the 

numeric impingement mortality performance standard. Under this alternative, the owner or 

operator has the flexibility to choose any technology, including a new or innovative technology, 

provided the compliance monitoring demonstrates the standard is achieved. 

EPA is promulgating an entrainment standard based on site-specific entrainment controls 

determined by the EPA or the State permitting authority for existing facilities (other than new 

units) that withdraw amounts of cooling water that exceed the applicability threshold. Requiring 

a structured site-specific analysis of candidate BTA technologies for entrainment control will 

allow the Director to determine where it is appropriate to require such controls. One outcome of 

the site-specific analysis could be that the Director would determine that no other technologies 

beyond impingement control meet the criteria for selection as BTA. For example, the Director 

could determine that no other technologies are feasible and/or the benefits do not justify the 

costs. 

As described in the preamble to the final rule, EPA obtained estimates of regional impingement 

mortality and entrainment by extrapolating IM&E observed at 97 facilities with IM&E studies 

(model facilities) to all regulated facilities in the same region. EPA used regional estimates to 

more accurately estimate impacts by accounting for differences in ecosystems, aquatic species, 

and characteristics of commercial and recreational fishing activities across regions. EPA 

extrapolated on the basis of actual intake flow reported for the period 1996–1998 by facilities in 

response to EPA’s Section 316(b) Detailed Questionnaire and Short Technical Questionnaire. 

Because the goal of the analysis is to provide estimates of IM&E at regional and national scales, 

EPA recognizes that these averages may not reflect the substantial variability at individual 

facilities. In spite of this variability, this extrapolation is a reasonable basis for developing 

estimates of regional and national benefits. 

Essay 78 399 
Essay 81: Loss Metrics

Several commenters criticized EPA’s use of age-one equivalents (A1E), foregone yield, and 

biomass production foregone as inappropriate. This essay responds to these comments. 

The New York State Department of Environmental Conservation (NYSDEC; comment 2260) 

and National Wildlife Federation (comment 2188) suggest that the use of A1E, Foregone Fishery 

Yield (FFY), and Biomass Production Foregone (BPF) are inappropriate for establishing a 

national rule because these metrics do not account for nonuse benefits (e.g., ecosystem 

processes, food web stability, etc.) associated with the regulation of CWIS. Instead, these 

commenters state, and Riverkeeper (comment 2391) implies, that the correct metric to use is the 

raw number of individuals (e.g., the count of all eggs, larvae, juveniles, and adult fish) lost due to 

CWIS operation. All comments asserted that nonuse benefits are the primary benefits to be 

gained by the rule. 

EPA agrees that nonuse benefits are the primary environmental benefits to be achieved as a 

result of the rule. However, it disagrees with the suggestion that its use of A1E, FFY, and BPF 

are not suitable for its analysis. Although nonuse benefits are the primary benefits to be gained 

by the rule, they are not the only benefits to be gained. EPA used FFY and BPF metrics in its 

estimates of commercial and recreational fishing benefits likely to occur following rule 

implementation (see Chapters 6 and 7 of the BA for further discussion). 

In comment 2260, NYDEC argues that the raw number of organisms lost to IM&E is the correct 

metric for analysis (a metric presented in Appendix C of the BA), because it incorporates all 

adverse environmental impacts caused by CWIS. Additionally, in comment 2188, NWF argues 

that the use of A1E ignores the importance of early life history stages in the ecosystem. EPA 

disagrees with both commenters, and notes that the derivation of the A1E metric includes a count 

of all organisms lost to IM&E (e.g., the metric suggested by NYDEC, including counts of eggs, 

larvae, juveniles, adult fish, etc.), weighted by the probability of survival to age one. Thus, the 

metric includes all raw organism count data, and acknowledges the importance of early life 

history stages in the food ecosystem, but also recognizes that the importance of each organism to 

the ecosystem is not equivalent. For example, an average fish egg plays a substantially less 

important role in an ecosystem than an adult fish of the same species. This is true when 

measuring the importance of an individual to inter- and intra-specific competition, population, 

nutrient and energy flows, and other ecosystem processes. 

EPA does not agree with NYDEC (comment 2260) that metrics used in the analyses provide no 

accounting for nonuse benefits. In the proposed rule, EPA presented a habitat based 

methodology for estimating nonuse values of fish production. Although not incorporated into the 

final rule, this analysis explicitly used A1E losses to estimate nonuse benefits. Additionally, in 

the final rule, EPA uses a benefits transfer approach to estimate the nonuse benefits of regulation 

through application of a model that estimates willingness to pay (WTP) for anadromous fish 

habitat restoration (Zhao et al. 2013; DCN 12-5060). Finally, EPA used the A1E metric in the 

development of a stated preference survey for the final rule to enable nonuse benefits to be 

incorporated into the benefit-cost comparison (see Chapter 11 of the BA for further discussion). 

Essay 81 400 
EPA notes that the extensive focus group testing conducted as part of developing the survey 

demonstrated that the public understood the concept of young fish as having value, which can be 

restated in technical terms as age-one equivalents having nonuse value. 

Essay 81 401 
Essay 82: Assessment and Extrapolation of Impingement Mortality and

Entrainment

While attempting to estimate national IM&E, EPA faced several difficulties. As was noted in 

several comments, much of the data used to generate these estimates come from the 1970s and 

1980s. EPA recognizes that there have been many changes in the ecosystem over the past 

decades, and agrees that estimates of IM&E generated from modern facility-level IM&E studies 

may produce results that are very different. Additionally, EPA recognizes that there are many 

sources of potential error in IM&E studies, the use of age-equivalent models, and the use of an 

extrapolation model to estimate losses at facilities without studies. However, EPA notes that in 

each case (with two notable exceptions), commenters do not provide new data nor do they 

suggest how the use of available data could be improved. 

Data Quality and Age

Several commenters (e.g., Riverkeeper: comment 2391; AES: comment 2458) noted that the data 

used by EPA to extrapolate losses are sometimes decades old, and that changes to environmental 

quality and status of fisheries insert substantial uncertainty into estimates of IM&E. EPA 

recognizes that the age and quality of IM&E studies used to estimate baseline losses nationally 

are a major source of uncertainty, and would have preferred to use more recent studies to 

estimate regional and national losses. However, the decades-old studies are, in most cases, the 

only data currently available and suitable for extrapolation. As noted by commenters, whenever 

possible, EPA corrected IM&E loss rates to account for several factors, including the installation 

of IM&E-reducing technologies (e.g., velocity caps, periodic flow reductions, etc.), seasonality, 

diel cycles, etc, in order to make these old studies comparable. However, other quality issues 

associated with some studies (e.g., not all species suffering from IM&E were reported) cannot be 

corrected, leading to an underestimate of losses for some species. EPA notes, however, that the 

most commonly captured species were reported (whenever identifiable) in all studies, suggesting 

that any species-level underestimates are unlikely to have a significant impact on estimates of 

national IM&E. Regardless of age and quality issues associated with some studies used in 

regional extrapolation models, the inclusion of these studies was necessary to obtain the data 

sufficient to estimate national baseline losses. 

Cognizant of the fact that many old IM&E studies have substantial uncertainty, and because 

EPA’s estimates of baseline losses propagate through the entire benefit analysis, modern IM&E 

studies are incorporated into the extrapolation models whenever they have been identified. 

Additionally, best practices for the use of age equivalency and production foregone models (e.g., 

EPRI report 1008471, DCN 11-6506C) identified in comment 2962 (EPRI) were reviewed, and 

their recommendations compared against EPA’s approach: no changes were necessary. 

Furthermore, “default” estimates of fish life history parameters provided by commenters (e.g., 

EPRI reports 1008832 and 1023103; provided in comment 2962) were compared against 

parameters used by EPA (as reported by individual facilities used in extrapolation). In all cases, 

parameters were very close to each other, and no modifications were made to the values used in 

extrapolation by EPA. 

Essay 82 402 
In some cases, the incorporation of modern IM&E studies may substantially alter regional 

estimates of losses. For example, within comment 2391, Riverkeeper claims fish losses in the 

Great Lakes region were underestimated by an order of magnitude, based upon a recent (2008), 

high quality study of IM&E at the Bay Shore power plant. EPA thanks Riverkeeper for 

identifying this study, which was included in regional IM&E calculations used in the final rule. 

The direct result of this study’s incorporation is clear: EPA’s estimates of raw losses for many 

fish species in the Great Lakes increased by several orders of magnitude, despite an overall 

decrease in baseline intake flow (> 15 percent), due to New York’s state standards requiring 

closed-cycle cooling at all in-state facilities with design intake flow greater than or equal to 

20 million gallons per day, many of which are in the Great Lakes region (Table 1). 

Table 1: Changes in EPA’s estimate of raw losses for several species of 

fish in the Great Lakes Region (all values in millions of raw losses) 

Species Initial Estimate Revised Estimate 

Walleye < 0.01 25.96 

Freshwater Drum 221.27 4,153.88 

Logperch 10.48 88.35 

White Perch < 0.01 704.63 

Without the inclusion of several new studies, however, EPA is unable to determine the extent to 

which new studies would alter regional IM&E estimates in other regions. 

Overall, EPA agrees with the comments suggesting that its estimates of baseline fish IM&E are 

greatly affected due to the (necessary) use of old data. However, EPA disagrees that its estimates 

are unreliable and likely to be an underestimate of baseline losses. Although EPA agrees that 

new data would increase the overall accuracy of regional and national estimates, these data do 

not exist (but will be collected as a consequence of rule implementation), and EPA has used the 

best data available when producing estimates of regional and national IM&E losses. 

Problems with Age Equivalency Models

In addition to the age and data quality issues, commenters noted several potential problems with 

the data used to parameterize the age equivalency (e.g., age-one equivalent, or A1E) model to 

estimate baseline national values of IM&E. These issues include separation of IM&E data into 

correct life history stages by species, and accurate survivorship factors. 

In many IM&E studies used by EPA to estimate national baseline losses, specific ages of 

impinged fish were reported. EPA agrees with Riverkeeper (comment 2391) that determining the 

age of fish can be inexact and time-consuming. However, EPA notes that age-length 

relationships are well-established in the fisheries biology literature, and that such a conversion 

(either from age to length, or from length to age) was necessary to make all studies comparable. 

Moreover, EPA notes that age-length relationships are based upon averages. Therefore, the use 

of such relationships is statistically unbiased, and therefore may underestimate or overestimate 

actual ages (and therefore age-equivalent losses). 

Essay 82 403 
As is noted by Riverkeeper in comment 2391, the determination of accurate survivorship factors 

is exceptionally difficult. In many cases, survivorship factors may change annually as a function 

of natural variability (e.g., of water temperature, sunlight, etc.) and anthropogenic factors (e.g., 

fishing pressure, water quality, etc). Based upon these (and other) factors, fish populations vary 

from year to year, although they are expected to be stable over the long term. Accordingly, 

although survivorship may vary among years, survivorship factors are fixed within the model. 

EPA recognizes that the assumption of fixed survivorship factors increases model uncertainty, 

but that estimates are likely to be unbiased and that accordingly, the overall direction and 

magnitude of this uncertainty is unknown. However, given that EPA used a total of 270 

survivorship schedules in its estimation of regional IM&E losses, it is likely that survival is 

underestimated for some species, overestimated in others, and that across all species, the 

directional error aggregated across all species is likely to be a small proportion of total losses. 

With respect to survivorship factors, commenters also note that survivorship may vary among 

sites, particularly at the geographic extremes of species ranges. EPA agrees with this assessment, 

and notes that the extrapolation model incorporates multiple survivorship schedules for species 

with wide-ranging habitat ranges. For example, there are five separate survivorship schedules for 

Alewife, with one schedule used in each of the Great Lakes, Inland, and North Atlantic regions, 

and two schedules used (for northerly and southerly facilities) within the Mid-Atlantic region. 

In comment 3006, Entergy suggests that the life stages of fish subject to impingement and 

entrainment should be considered in the analysis, since the impact to a fish population varies by 

life history stage. EPA notes that the use of age equivalency models expressly takes life history 

into account, weighting the loss of early life history stages (e.g., egg and larval stages) lower 

than the loss of adult fish. EPA also notes that none of its analyses assess changes in fish 

populations, and consequently, suggestions relating to the accurate calculation of changes in 

local fish populations occurring due to CWIS are not relevant. 

Although commenters recognize the utility of age equivalency models, some noted that they do 

not take into account for ecological effects of CWIS operation beyond IM&E. Whenever 

possible, EPA took broader ecological impacts into account (e.g., the value of forage fish was 

recognized through the use of trophic transfer), though this was not possible in many cases. For 

example, EPA acknowledges that there are other effects of CWIS operation, including flow and 

thermal alteration, effects on non-aquatic organisms (e.g., birds), and the potential for impacts on 

decomposers. EPA agrees with Riverkeeper that these effects are poorly studied, are difficult to 

detect reliably, and may be hidden by other anthropogenic impacts (e.g., fishing, climate change, 

channelization, nutrient cycling, land use change, etc.). EPA notes, however, that it may be 

possible to characterize such impacts of CWIS operation at individual facility locations with 

additional study. Similarly, positive, localized impacts of CWIS operation (e.g., thermal refugia 

for manatees, as identified by in comment 2458) may be identified more readily using sitespecific studies. 

Biomass Transfer Among Trophic Levels

In estimating the benefits of reduced fish kills, EPA assumed a trophic transfer efficiency of 0.10 

for all trophic levels. This value indicates that 10 percent of the biomass at one trophic level 

(e.g., forage species) is incorporated into the next highest trophic level (e.g., predatory fish). 

Essay 82 404 
Although EPA recognizes that there may be substantial variability among habitats, this 

assumption is derived from the work of Pauly and Christensen (1995; DCN 12-4954) and is used 

as a baseline assumption by many ecologists when the true underlying trophic dynamics of an 

ecosystem are unknown. 

Notably, the values of trophic efficiency (TE) compiled by Pauly and Christensen are not 

habitat-specific, but are specific to trophic levels within specific geographic regions (e.g., the 

140 estimates of trophic efficiency compiled by Pauly and Christensen (1995) come from 48 

food webs). The raw data indicate that there is substantial variability not only among sites within 

aquatic ecosystem (e.g., freshwater ponds and lakes, coastal areas, shelves and open ocean), but 

also among trophic levels within sites (e.g., TE within Lake Kinneret varied between 3 and 19 

percent) (Christensen and Pauly 1993; DCN 12-5070). Accordingly, due to the complexity of 

multi-species food webs and the trophic-level and location-specific nature of trophic transfer 

rates, EPA agrees with commenters that “the efficiency with which food passes from one trophic 

level to another is very difficult to estimate” and is likely to “vary greatly from ecosystem to 

ecosystem and from species to species.” Given that (i) species- and ecosystem-specific estimates 

of trophic transfer efficiency are not available in the literature, and (ii) it was not feasible to 

develop individual estimates at local or regional scales, EPA concluded that the use of an 

average rate of 10 percent for all regions and trophic interactions was an appropriate choice. 

Extrapolation from Facilities to Regions

Many facilities subject to the final rule have never conducted impingement or entrainment 

studies. Accordingly, to generate regional and national estimates of baseline IM&E losses, EPA 

was forced to group these stations into regions, and extrapolate within these regions. 

Accordingly, EPA does not report nor estimate facility-level estimates of impingement and 

entrainment. Site-specific data were, however, used to populate regional loss models. In doing 

so, EPA incorporated data collected during Phase II and III implementation, and newer data 

whenever identified. In all cases, losses reported in IM&E studies were modified to account for 

modifications in facility CWIS design, including new IM&E mitigation measures. 

EPA notes that because there is a great deal of variability in fish production among sites within 

regions, these extrapolations are highly uncertain. The direction and magnitude of uncertainty in 

regional-scale model extrapolations, however, are unknown. In some cases, facility IM&E 

studies were conducted in a geographically dispersed manner over several decades, and are 

therefore likely to be unbiased estimators of regional losses. In other cases, however, facilities 

may have been forced to conduct IM&E studies because of regionally high losses of species or 

the presence of important commercial and recreational fish species, in which case the use of 

these studies is likely to overestimate losses. Although EPA would prefer not to have to use an 

extrapolation procedure to estimate regional and national baseline losses, such a procedure is 

necessary given the overall lack of sampling data. Importantly, in comment 2391, Riverkeeper 

agrees, stating that using extrapolated data is “probably the only method available.” 

Limitations and Uncertainty

EPA acknowledges that its regional and national estimates of IM&E losses are uncertain, and 

agrees with commenters (e.g., AES in comment 2458, Riverkeeper in comment 2391; Entergy in 

comment 3006; Midwest Generation in comment 2245) that many factors contribute to this 

Essay 82 405 
uncertainty. Whenever possible, EPA incorporated methods to minimize these uncertainties. 

Uncertainties include (but are not limited to): 

	 Site-specific field sampling and scaling. This uncertainty is driven by field sampling 

protocols developed for individual facilities that may miss or capture episodic events. 

Whenever possible, EPA averaged across annual IM&E estimates to obtain loss estimates 

representative of the facility. Uncertainties in sampling and site-specific scaling may 

over- or under-estimate IM&E. 

	 Site-specific rates of trophic transfer efficiency. As noted above, there is a great deal of 

variability in trophic transfer efficiency both among species within ecosystems, and 

among ecosystems. Although published estimates of trophic transfer efficiency range 

from approximately 2 to 25 percent, EPA used an estimate of 10 percent for all species 

and ecosystems. Accordingly, the use of a global mean may over or underestimate true 

levels of IM&E. 

	 Species-specific feeding patterns. In its models, EPA assumes that all forage fish species 

are consumed by harvested species, but recognizes that this represents an upper bound. 

	 Species identification. In many cases, it is not possible to identify organisms to species 

due to inadequate study, inadequate morphological development necessary to 

differentiate among species (this is particularly true for early life history stages), and/or 

physical damage to organisms caused by impingement or entrainment. When organisms 

were not identified to species, EPA classified these losses either by species group (e.g., 

“salmon”), or categorized these losses as “other species.” Miscategorization of 

individuals will overestimate losses of the species assigned inappropriately while 

underestimating losses of the species misassigned. Because of these offsetting values, it is 

unlikely that inaccurate species identification will meaningfully affect regional or 

national IM&E estimates. 

	 Impinged and entrained organism health. In some cases, the health of impinged and 

entrained organisms may be impaired, or they may be dead upon arrival at the intake. 

Whenever possible, EPA took organisms health into account. However, the vast majority 

of facility IM&E studies did not note the health or impinged organisms, and it is not 

possible to extrapolate organism health among facilities. 

	 Entrainment survival. EPA models entrainment mortality to be 100 percent, but 

recognizes that this is an upper bound. Actual entrainment mortality may be less than 100 

percent for some facilities, times of year, or species. 

	 Undercounting. Many facility IM&E studies report that many fish eggs and larvae were 

damaged by the sampling protocol, and could not reliably identified or even counted. 

Consequently reported entrainment estimates from facility IM&E studies are likely to be 

underestimates. 

	 Periodic nature of mass impingement and entrainment events. In some facility studies, a 

high percentage of annual IM&E was observed in one or two sampling periods. To the 

extent that these events are included (or missed) in facility sampling protocols, and 

important to average IM&E by species or region, EPA may over- or underestimate 

IM&E. 

Essay 82 406 
	 Annual variability in loss rates driven by changes in local fish populations. Whenever 

possible, EPA obtained multiple years of data for each model facility. However, there are 

many facilities for which only a single year of data were available. Because fish 

populations and communities may vary substantially on an annual basis, IM&E estimates 

bay be over- or underestimated for individual species, and for the community as a whole. 

The direction of this uncertainty, however, is unknown. 

	 Changes in life histories driven by population changes. EPA recognizes that survival 

rates may vary substantially from year to year, based upon changes in food ability, 

predator density, water temperature, etc. EPA was unable to account for annual changes 

in life history parameters. The effect of life history uncertainty is unknown, and may 

over- or underestimate IM&E losses. 

	 Changes in waterbody characteristics and populations due to the age of facility data. As 

noted above, EPA incorporated the most recent IM&E studies available, but notes that 

studies in many areas of the country may be decades old, and fish populations may be 

substantially different (higher or lower) than when data were collected. However, the 

decades-old studies are, in most cases, the only data currently available and suitable for 

extrapolation. In these cases, actual IM&E losses may be higher or lower than estimated 

from historical data. 

Overall, EPA acknowledges that there are many sources of uncertainty in the data underlying 

IM&E estimates, and agrees that regional and national estimates of IM&E are highly uncertain. 

However, the direction of many sources of uncertainty is unknown (e.g., uncertainty may result 

in either over- or under-estimates of IM&E), while other uncertainties are offsetting (e.g., for 

some factors, uncertainty will result in over-estimates, while for other factors, uncertainty results 

in under-estimates). On the whole, and at regional and national scales, EPA judges its estimates 

of IM&E to be unbiased. 

Essay 82 407 
Essay 83: Entrainment Mortality

EPA received several comments with respect to entrainment mortality. This essay responds to 

these comments. 

Assumption of 100 Percent Entrainment Mortality

Comments by Riverkeeper (comment 2391) were strongly supportive of EPA’s assumption for 

national modeling, namely that the mortality rate of entrained organisms is 100 percent. 

Comments by Entergy, Midwest Generation - Edison Mission Energy, AES North America, and 

EPRI (comments 2347, 2245, 2458, and 2200) are in direct opposition to EPA’s stance, noting 

that the mortality rate of entrained organisms will not be 100 percent at all facilities. 

Consistent with its treatment of entrainment in past national 316(b) rules, EPA has not changed 

its long standing views that 100 percent of entrained organisms suffer mortality. See Essay 18. 

Commenters failed to provide new information or basis for changing EPA’s position regarding 

entrainment mortality. 

Through-plant entrainment survival has been studied extensively, with EPRI’s Review of 

Entrainment Survival Studies being amongst the most comprehensive. See DCN 2-017A-R7 

from the Phase I docket. With respect to the regional and national IM&E modeling, EPA notes 

that facility characteristics relevant to entrainment survival (e.g., heat load, biocide 

concentrations, transit time, turbulence and shear stress, etc.) vary among CWIS systems (i.e., at 

different facilities), and differ throughout the year within CWIS systems (e.g., due to seasonal 

changes in CWIS operation). The extent to which these factors may affect survival in facilities 

whose data were used to model entrainment remains unknown. Notably, EPA identified no 

suitably designed studies of entrainment mortality that (1) occurred parallel to a suitable 

entrainment sampling protocol used to develop regional estimates of IM&E, (2) assessed intraannual variability, and (3) assessed entrainment survival rates for a sufficient number of species 

that would justify regional extrapolation to dozens of species. 

Second, because fish eggs and larvae are soft bodied and are frequently extremely fragile, counts 

of entrained eggs and larvae (and to a lesser extent, juvenile fish) are under-counted by studies of 

entrainment at regulated facilities. Several IM&E reports suggest that entrainment samples may 

contain a high (but unquantifiable) number of eggs and larvae destroyed by mechanical stress. 

Thus, uncertain rates of entrainment survival will be offset by similarly uncertain rates of underreporting. 

Third, EPA notes that a high proportion of the studies used to extrapolate entrainment losses to 

the regional level may be decades old. To the extent possible, EPA accounted for changes in 

CWIS operation, design, and the installation of IM&E reducing technologies. However, the 

extent to which these changes may affect entrainment survival is unknown. When combined with 

a poor understanding of existing entrainment mortality, these changes make EPA unable to 

entertain estimates of entrainment survival in its calculations. 

Essay 83 408 
Fourth, EPA notes that long-term survival rates of entrained organisms (e.g., eggs, larvae, 

juveniles) due to shock, behavioral disturbance, and other factors, are dramatically lower than 

organisms that were never entrained. Thus, survival through the cooling water system does not 

indicate that mortality has been avoided. 

Consequently, on the basis of the record information it has reviewed, EPA concluded for 

purposes of this rule that no entrained organisms survive. (See, for example, 76 FR 22188 [April 

20, 2011] and 69 FR 41620 [July 9, 2004]. Also see Chapter A7 of the Phase II Regional Studies 

Document (DCN 6-0003; EPA-HQ-OW-2002-0049-1490.) 

Relevance to the Final Rule and Determination of BTA

Although EPA disagrees with commenters that its modeling assumption of 100 percent 

entrainment mortality is faulty, these commenters’ concerns are not relevant for purposes of the 

final rule because the rule does not establish a specific national numeric entrainment reduction 

standard. Instead, the rule establishes a national BTA standard for entrainment that requires the 

establishment of entrainment reduction control measures on a site-specific basis in a prescribed 

permitting setting (see Section VI of the preamble and Essay 15 for additional information). 

Moreover, EPA notes that a significant amount of information will be collected and submitted 

for review as a consequence of rule implementation. Notably, EPA does allow for consideration 

of entrainment survival: the rule allows for facilities to demonstrate to the Director that 

entrainment mortality is less than 100 percent, as long as such a demonstration is general, and 

therefore not a demonstration specific to those species whose eggs and/or larvae are hardier. 

Essay 83 409 
Essay 84: Impacts on Threatened and Endangered Species

EPA received several comments with respect to impacts on threatened and endangered species. 

This essay responds to these comments. 

Inability to Account for All Impacts

In its comments, the National Wildlife Federation (NWF; comment 2188) reiterates many of 

EPA’s findings with respect to the effects of CWIS on threatened and endangered (T&E) 

species, and notes that impacts on T&E species are not fully accounted for in the Benefits 

Analysis (BA). EPA has noted that data and other limitations limit EPA’s ability to take effects 

on T&E species fully into account in its analyses. 

Impacts of Regulated Facilities on T&E Species

In its comment, NWF (comment 2188) highlights four regulated facilities as causing IM&E of 

T&E species protected by the ESA: the Contra Costa and Pittsburg power plants in San 

Francisco Bay, the Indian Point Energy Center (a nuclear power facility) on the Hudson River 

(NY), and facilities at the Crystal River Energy Complex (CREC) in Florida. Although likely 

chosen by NWF as example facilities, EPA points to the effectiveness of existing regulation in 

protecting T&E species at these facilities. 

The Contra Costa facility has closed. Therefore, it has ceased to be a source of IM&E of T&E 

species, and any facilities brought online to replace generating capacity will not be subject to this 

rule. 

The Pittsburg power plant, located in California, is subject to 316(b) regulations in the State of 

California. The policy of the California State Water Resources Control Board requires closedcycle cooling for all power plants that withdraw water from estuaries and coastal waters. 

Therefore, the facility is subject to regulation that significantly reduces IM&E (see Section IX.A 

of the preamble to this rule for details) of species generally and T&E species in particular. 

The Nuclear Regulatory Commission recently consulted with the National Marine Fisheries 

Services (NMFS) on the effects of the continued operation of the Indian Point power plant in 

New York to listed species and designated critical habitat. In the Biological Opinion, NMFS 

determined that the facility was likely to adversely affect but unlikely to jeopardize the continued 

existence of shortnose sturgeon or Atlantic Sturgeon. As part of this consultation for Indian Point 

power plant, NMFS included an incidental take statement (ITS) that limits incidental take and 

requires reinitiation of the consultation process if the amount of take exceeds that permitted by 

the ITS. EPA also notes that Indian Point is subject to the 316(b) regulations in the State of New 

York, which have identified closed-cycle cooling as BTA, and will consequently minimize 

IM&E impacts on shortnose sturgeon (see Section IX.A of the preamble to this rule for details). 

CREC, in Florida, has formally consulted with NMFS with respect to the take of T&E turtles. 

NMFS’s biological opinion concluded that the continued operation of the CREC is not likely to 

jeopardize the existence of any of the five T&E turtle species. As a condition of the consultation, 

Essay 84 410 
which included an ITS, CREC must submit annual reports for the incidental take of sea turtles, 

and consultation must be reinitiated if the ITS if permitted take is exceeded. 

Therefore, of the four facilities highlighted by NWF, one is closed, two are subject to state-level 

regulation that will require the installation of closed-cycle cooling technologies to minimize 

IM&E, and two have conducted formal ESA consultations. EPA also notes that each of the 

facilities that remain open will be subject to additional requirements to ensure impact on T&E 

species is minimized, including the identification of all nearby T&E species and/or critical 

habitat, characterization of source waters, and studies of impingement and entrainment. 

Potential for IM&E of T&E Species

In comment 2223, NewPage Corporation asserts that the methods EPA uses to determine the 

potential for T&E loss is flawed because it does not take into account the life history 

characteristics of the species at risk, and because EPA did not consider the status of these 

species. Additionally, several comments (2151, 2180, and 2223) requested clarification about the 

genesis of IM&E rates for listed species, and expressed concern that the IM&E of T&E species 

may be extrapolated to the regional scale based only upon geographic proximity to facilities 

reporting IM&E. 

EPA disagrees with comment 2223. In Chapter 5 of the BA, EPA presents two methods to 

estimate the impact of CWIS on T&E species. In the first method, EPA assesses the overlap 

between CWIS and T&E species. In this analysis, EPA does not assert that all species with 

habitat overlapping a CWIS are directly harmed, only that the potential for harm exists. Potential 

harm to T&E species may be direct (e.g., IM&E), or indirect (e.g., reduction of prey, changes to 

physical habitat). Because EPA considered the potential for indirect effects of CWIS operation 

on T&E species, detailed life history characteristics of species at risk, other than the use of 

aquatic habitat, were not directly relevant for this analysis. Moreover, since EPA collected 

habitat data only for T&E species, the status of all species in this analysis was considered 

explicitly. 

The second method used by EPA to estimate CWIS effects on T&E species was to identify all 

species with documented IM&E. For this analysis, an analysis of life history traits is 

unnecessary, because EPA presents only species with documented IM&E, and does not 

extrapolate results to regional or national scales. Instead of extrapolating, EPA aggregates 

reported facility level IM&E of T&E species, and consequently does not map IM&E to facilities 

based only on geographic proximity. Two categories of T&E species were presented in this 

analysis: a list of all T&E species with IM&E mortality, and a list of organisms not identified to 

species, but whose genus matched T&E species lost at a regulated facility’s CWIS. In this 

analysis, EPA recognizes that losses matching T&E species’ genus are likely to be dominated by 

more common congeners (i.e., species not protected by the ESA). 

Therefore, in all analyses presented in the T&E chapter of the BA, EPA takes life history 

characteristics into consideration when necessary, and explicitly considers the status of all 

species included in the analysis. 

Essay 84 411