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EO12866_Cooling Water Intakes_2040_AE95_Final_Preamble_20130722+Rule 

_20140519

ENVIRONMENTAL PROTECTION AGENCY 

40 CFR Parts 9, 122, 123, 124, and 125 

[EPA-HQ-OW-2008-0667, FRL – 9817-3] 

RIN 2040–AE95

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 

AGENCY: Environmental Protection Agency (EPA). 

ACTION: Final rule. 

SUMMARY:SUMMARY: The purpose of this action is to reduce impingement and 

entrainment of fish and other aquatic organisms at cooling water intake structures used by 

certain existing power generation and manufacturing facilities for the withdrawal of 

cooling water from waters of the United States. This rule establishes requirements under 

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

existing manufacturing and industrial facilities that are designed to withdraw more than 2 

million gallons per day (MGDmgd) of water from waters of the U.S.United States and 

use at least twenty-five (25) percent of the water they withdraw exclusively for cooling 

purposes. These national requirements, which will be implemented through National 

Pollutant Discharge Elimination System (NPDES) permits, apply to the location, design, 
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construction, and capacity of cooling water intake structures (CWIS) at regulated 

facilities by settingand provide requirements that reflect the best technology available 

(BTA) for minimizing adverse environmental impact. On April 20, 2011, EPA published 

a proposed rule that included several options for addressing these impacts. Subsequently, 

EPA published two Notices of Data Availability (NODA), on June 11, 2012 and June 12, 

2012, that further clarified EPA’s proposed approach. This final rule constitutes EPA’s 

responsealso responds to thejudicial remand of theaspects of the previously promulgated

Phase II and Phase III section 316(b) rules. In addition, EPA is also responding to thean 

earlier judicial decision in Riverkeeper I to removeby removing from the previously 

promulgated Phase I new facility rule thea restoration-based compliance alternative and 

the associated monitoring and demonstration requirements. 

DATES: This regulation is effective [INSERT DATE 60 DAYS AFTER DATE OF 

PUBLICATION IN THE FEDERAL REGISTER]. For judicial review purposes, this 

final rule is promulgated as of 1 p.m. EDT (Eastern Daylight Time) on [INSERT DATE 

14 DAYS AFTER DATE OF PUBLICATION IN THE FEDERAL REGISTER] as 

provided in 40 CFR 23.2. 

ADDRESSES: EPA has established a docket for this action under Docket ID No. EPAHQ-OW-2008-0667. All documents in the docket are listed on the www.regulations.gov

Webweb site. Although listed in the index, some information is not publicly available, 

e.g., CBI (confidential business information) or other information whose disclosure is 

restricted by statute. Certain other material, such as copyrighted material, is not placed on 
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the Internetinternet and will be publicly available only in hardcopy form. Publicly 

available docket materials are available either electronically through 

www.regulations.gov or in hardcopy at the Water Docket in the EPA Docket Center, 

EPA/DC, EPA West, Room 3334, 1301 Constitution Avenue, NW., Washington, DC. 

The Public Reading Room is open from 8:30 a.m. to 4:30 p.m., Monday through Friday, 

excluding legal holidays. The telephone number for the Public Reading Room is 202–

566–1744, and the telephone number for the Water Docket is 202–566–2426. 

FOR FURTHER INFORMATION CONTACT: For additional technicalbiological

information, contact Paul ShrinerTom Born at 202–-566–1076-1001; e-mail: 

shriner.paul@epa.govborn.tom@epa.gov. For additional economic information, contact 

Wendy Hoffman at 202–564–8794; e-mail: hoffman.wendy@epa.gov. For additional 

biologicaltechnical information, contact Tom BornPaul Shriner at 202-–566-1001–1076; 

e-mail: born.tomshriner.paul@epa.gov. 

SUPPLEMENTARY INFORMATION: 

What EntitiesFacilities Are Regulated By This Action? 

This final rule applies to existing facilities that use cooling water intake structures 

to withdraw water from waters of the United States and have or require an NPDES 

(National Pollutant Discharge Elimination System) permit issued under section 402 of the 

CWA (Clean Water Act). Existing facilities subject to this regulation include those with a 

DIF (design intake flow (DIF) greater than 2 mgd (million gallons per day).. If a facility 

meets these conditions, it is subject to today’s final regulations. If a facility has or 

requires an NPDES permit but does not meet the 2 mgd intake flow threshold, it is 

Field Code Changed
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subject to permit conditions implementing CWA section 316(b), developed by the 

NPDES permit directorPermit Director on a site-specificcase-by-case basis using BPJ 

(best professional judgment) under 40 CFR 125.90(b). This final rule defines the term 

cooling water intake structure to mean the total physical structure and any associated 

constructed waterways used to withdraw cooling water from waters of the United States, 

provided that at least 25 percent of the water actually withdrawn is used for cooling 

purposes.. The cooling water intake structure extends from the point at which water is 

first withdrawn from waters of the surface waterUnited States source up to, and 

including, the intake pumps. Generally, facilities that meet these criteria fall into two 

major groups: steam electric generating facilities and manufacturing facilities. The final 

rule also makes limited changes to the requirements for Phase I facilities (i.e., new 

facilities). 

Exhibit 1 lists the typesindustry sectors of entities that are potentiallyfacilities

subject to this final rule. This table is not intended to be exhaustive, but it provides a 

guide for readers regarding entities likely to be regulated by this action. Other types of 

entities; facilities in other industries not listed in the tableExhibit 1 could also be 

regulated. The 4-digit NAICS industry sectors may include 6-digit NAICS industry subsectors with operations that are not dependent on cooling water.

Exhibit 1. Industry Sectors with Facilities Subject to the Final Rule 

Exhibit 1. Example regulated entities and their codes 

Category 

Examples of 

Regulated Entities

Standard 

Industrial 

North 

American4- NAICS Definition

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Classifica

tion 

Codes

Digit NAICS

Industry 

Codes 

(NAIC)Sectors

Federal, State and Local Government 

Operators of 

steam electric 

generating 

point source 

dischargers 

that employ 

cooling water 

intake 

structures.Elec

tric Power 

Industry

4911 and 493

221111, 221112, 221113, 

221119, 221121, 221122, 

221111, 221112, 221113, 

221119, 221121, 221122

 2211 Electric Power Generation, Transmission and 

Distribution 

Industry 

Operators of 

industrial point 

source 

dischargers 

that employ 

cooling water 

intake 

structures.Elec

tric Power 

Industry

See below

See below

 Steam electric 

generating2211

4911 and 

493Electric Power 

Generation, 

Transmission and 

Distribution

221111, 221112, 221113, 

221119, 221121, 221122, 

221111, 221112, 221113, 

221119, 221121, 221122

Industry

Agricultural 

productionPrim

ary 

Manufacturing 

Industries

0133

111991, 11193

 Metal mining 1011 21221 

Deleted Cells

Deleted Cells
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 3112

Oil and gas 

extraction (excluding 

offshore and coastal 

subcategories)Grain 

and Oilseed Milling

1311, 

1321

211111, 

211112

 3113

Mining and 

quarrying of 

nonmetallic 

mineralsSugar and 

Confectionery 

Product 

Manufacturing

1474 212391

 3121 Beverage Manufacturing 

 3221

FoodPulp, Paper,

and kindred 

productsPaperboard 

Mills

2046, 

2061, 

2062, 

2063, 

2075, 

2085

311221, 

311311, 

311312, 

311313, 

311222, 

311225, 

31214 

 Tobacco 

products3222

2141Converted 

Paper Product 

Manufacturing

312229, 31221

 Textile mill products 2211 31321 

 3241

Lumber and wood 

products, except 

furniturePetroleum 

and Coal Products 

Manufacturing

2415, 

2421, 

2436, 

2493

321912,32111

3, 321918, 

321999, 

321212, 

321219

 3251 Basic Chemical Manufacturing 

 3252

Paper and allied 

productsResin, 

Synthetic Rubber, 

and Artificial 

Synthetic Fibers and 

Filaments 

Manufacturing

2611, 

2621, 

2631, 

2676

3221, 

322121, 

32213, 

322121, 

322122, 

32213, 

322291

 3253 Chemical and allied 

productsPesticide, 

28 

(except 

325 (except 

325182, 

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Deleted Cells

Deleted Cells

Inserted Cells

Deleted Cells

Deleted Cells

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Deleted Cells

Deleted Cells

Inserted Cells

Deleted Cells

Deleted Cells
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Fertilizer, and Other 

Agricultural 

Chemical 

Manufacturing

2895, 

2893, 

2851, 

and 

2879)

32591, 

32551, 

32532) 

 3254

Petroleum refining 

and related 

industriesPharmaceu

tical and Medicine 

Manufacturing

2911, 

2999

32411, 

324199

 3256

Rubber and 

miscellaneous 

plastics 

productsSoap, 

Cleaning 

Compound, and 

Toilet Preparation 

Manufacturing

3011, 

3069

326211, 

31332, 

326192, 

326299

 3259

Stone, clay, glass, 

and concrete 

productsOther 

Chemical Product 

and Preparation 

Manufacturing

3241 32731

 Primary metal industries 3312, 3313, 3315, 3316, 3317, 

3334, 3339, 3353, 3363, 3365, 

3366 

324199, 331111, 331112, 

331492, 331222, 

332618, 331221, 22121, 

331312, 331419, 331315, 

331521, 331524, 

331525 

 3311

Fabricated metal 

products, except 

machinery and 

transportation 

equipmentIron and 

Steel Mills and 

Ferroalloy 

Manufacturing

3421, 

3499

332211, 

337215, 

332117, 

332439, 

33251, 

332919, 

339914, 

332999

 3312 Steel Product Manufacturing from Purchased 

Steel 

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 3313

IndustrialAlumina

and commercial 

machineryAluminum 

Production and 

computer 

equipmentProcessin

g

3523, 

3531

333111, 

332323, 

332212, 

333922, 

22651, 

333923, 

33312

Industry 

Transportation 

equipmentOthe

r Industries

3724, 3743, 3764

336412, 333911, 33651, 

336416

 1119 Other Crop Farming 

 2122 Metal Ore Mining 

 

 3133

Measuring, 

analyzing, and 

controlling 

instruments; 

photographic, 

medical, and optical 

goods; watches and 

clocksTextile and 

Fabric Finishing and 

Fabric Coating Mills

3861 333315, 

325992

 

Electric, gas, 

and sanitary 

services3211

4911, 4931, 4939, 

4961Sawmills and 

Wood Preservation

221111, 221112, 221113, 

221119, 221121, 221122, 

22121, 22133

 Educational 

services3314

8221Nonferrous 

Metal (except 

Aluminum) 

Production and 

Processing

61131

 

Engineering, 

accounting, 

research, 

management 

and related 

services3322

8731Cutlery and 

Handtool 

Manufacturing

54171

 3329 Other Fabricated Metal Product Manufacturing 

Inserted Cells

Deleted Cells

Deleted Cells

Inserted Cells

Deleted Cells

Deleted Cells
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 3364 Aerospace Product and Parts Manufacturing 

 3391 Medical Equipment and Supplies Manufacturing 

To determine whether a facility could be regulated by this action, one should 

carefully examine the applicability criteria in § 125.91 of the final rule. For information 

regarding the applicability of this action to an entity, consult the personpersons listed for 

technical information in FOR FURTHER INFORMATION CONTACT. 

Supporting Documentation 

1. Docket

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 this action, any public comments received, and other 

information related to this action. Although a part of the official docket, the public docket 

does not include information claimed as Confidential Business Information (CBI) or 

other information, the disclosure of which, is restricted by statute. For information on 

how to access materials in the docket, see ADDRESSES above. To view docket 

materials, call ahead to schedule an appointment. Every user is entitled to copy 266 pages 

per day before incurring a charge. The Docket Center may charge $0.15 for each page 

over the 266-page limit, plus an administrative fee of $25.00. 
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2. Electronic Access 

You may access this Federal Register document and the docket electronically 

through the Web site http://www.regulations.gov by searching for Docket ID EPA-HQOW-2008-0667. For additional information about the public docket, visit the EPA 

Docket Center home page at http://www.epa.gov/epahome/dockets.htm. 

3. Technical Support Documents

The final regulation is supported by three major documents: 

 Economic Analysis for the Final Section 316(b) Existing Facilities Rule (EPA821-R-13-00414-001), referred to as the EA throughout. This document presents 

the analysis of compliance costs, closureseconomic impacts, energy supply 

effects, and a summary of benefits associated with the final rule. 

 Benefits Analysis for the Final Section 316(b) Existing Facilities Rule (EPA-821-

R-12-00314-005), referred to as the BA throughout. This document examines 

cooling water intake structure impacts and regulatory benefits at the regional 

leveland national levels. 

 Technical Development Document for the Final Section 316(b) Existing Facilities 

Rule (EPA-821-R-12-00814-002), referred to as the TDD (Technical 

Development Document) throughout. This document presents detailed 

information on the methods used to develop unit costs and describes the set of 

technologies that may be used to meet the final rule requirements. 
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Table of Contents 

I. Executive Summary and Scope of Today’s Rulemaking 

A. Executive Summary 

B. Scope of Today’s Rulemaking 

C. General Applicability 

D. What is an “Existing Facility” for Purposes of the Final Rule? 

E. What is “Cooling Water” and What is a “Cooling Water Intake Structure?” 

F. Would My Facility Be Covered Only If It Is a Point Source Discharger? 

G. Would My Facility Be Covered If It Withdraws Water from Waters of the United 

States? What If My Facility Obtains Cooling Water from an Independent Supplier? 

H. What Intake Flow Thresholds Result in an Existing Facility Being Subject to the 

Final Rule? 

I. I. What are the Requirements for Existing Offshore Oil and Gas Facilities, 

Offshore Seafood Processing Facilities or LNG Terminals BTA Requirements under the 

Final Rule?

J. What is a “New Unit” and How Are New Units Addressed Under the Final Rule? 

K. Amendments Related to the Phase I Rule 

II. Legal Authority for and Background of the Final Regulation 

A. Legal Authority 

B. Purpose of the Regulation 

C. Background 

III. Environmental Effects Associated with Cooling Water Intake Structures 

A. Introduction 

B. Major Anthropogenic Stressors in Aquatic Ecosystems 

C. Effects of CWIS on Aquatic Ecosystems 

D. Community–level or Indirect Effects of CWIS 

E. Cumulative Effects of Multiple Facilities 

 

IV. Summary Description of the Final Rule 

A. BTA Standard for Impingement Mortality for Existing Units at Existing Facilities

B. BTA Standard for Entrainment for Existing Units at Existing Facilities

C. BTA Standard for Impingement Mortality and Entrainment for New Units at 

Existing Facilities 

D. Other Provisions 

V. Summary of Most SignificantData Updates and Revisions to the Proposed Rule 

A. Data Updates 

B. Regulatory Approach and Compliance 
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C. New Units 

VI. Basis for the Final Regulation 

A. EPA’s Approach to BTA

BB. Overview of Final Rule Requirements

C. Technologies Considered to Minimize Impingement and Entrainment 

CD. Technology Basis for Today’s Final Rule 

D. Other Options Considered for Today’s Final Regulation 

E. Option Selection 

F. Other Options Considered for Today’s Final Regulation 

G. Final Rule BTA Performance Standards 

H. Economic and Benefit Analysis for the Final Rule 

GI. Site-Specific Consideration of Entrainment Controls 

VII. Response to Major Comments on the Proposed Rule and Notices of Data 

Availability (NODANODAs) 

A. Scope and Applicability 

B. Proposed Amendments Related to Phase I Rule 

C. Environmental Impact Associated with Cooling Water Intake Structures 

D. EPA’s Approach to BTA 

E. BTA Performance Standards 

F. Implementation 

G. Costs 

H. Monitoring and Reporting

I. EPA Legal AuthorityEndangered Species Act

VIII. Implementation 

A. When Does the Final Rule Become Effective and How are the Requirements 

Sequenced in an Orderly Way? 

B. How Does the Final Rule Reduce Biological Monitoring Requirements? 

C. What Information Will I Be Required to Submit to the Director When I Apply for 

My NPDES Permit? 

D. When Are Permit Application Studies Due? 

E. How Will the Director Determine the Best Technology Available for Minimizing 

Adverse Environmental Impacts? 

F. What are Example Permit Conditions and Compliance Monitoring for 

Impingement Mortality? 

G. What Monitoring is Required for Entrainment? 

H. What Reports Am I Required To Submit? 

I. What Records WouldWill I Be Required to Keep? 

J. What Are the Respective Federal, State, and Tribal Roles? 

K. Permits for Existing Facilities are Subject to Requirements under theProtection of

Endangered and Threatened Species Actand Designated Critical Habitat 
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L. Permits for Existing Facilities are Subject to Requirements under Other Federal 

 Statutes 

IX. Cost Development and Economic Impact Analysis 

A. Overview of Costs to Regulated Facilities and Federal and State Governments 

B. Development of Compliance Costs 

C. Social Costs 

D. Economic ImpactImpacts

E. Employment Effects 

X. Benefits Analysis 

A. Introduction 

B. Regional Study Design 

C. Physical Impacts of Impingement Mortality and Entrainment 

D. National Benefits of the Final Rule and Options Considered 

XI. Related Acts of Congress, Executive Orders, and Agency Initiatives 

A. Executive Order 12866: Regulatory Planning and Review and Executive Order 

13563: Improving Regulation and Regulatory Review 

B. Paperwork Reduction Act 

C. Regulatory Flexibility Act (RFA) 

D. Unfunded Mandates Reform Act (UMRA) 

E. Executive Order 13132: Federalism 

F. Executive Order 13175: Consultation and Coordination with Indian Tribal 

Governments 

G. Executive Order 13045: Protection of Children from Environmental Health Risks 

and Safety Risks 

H. Executive Order 13211: Actions that Significantly Affect Energy Supply, 

Distribution, or Use 

I. National Technology Transfer and Advancement Act 

J. Executive Order 12898: Federal Actions to Address Environmental Justice in 

Minority Populations and Low-Income Populations 

K. Executive Order 13158: Marine Protected Areas 

L. Congressional Review Act 
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I. Executive Summary and Scope of Today’s Rulemaking 

A. Executive Summary 

1. Summary of the Major Provisions of the Regulatory Action 

This rule establishes requirements under section 316(b) of the Clean Water Act 

(CWA) for existing power generating facilities and existing manufacturing and industrial 

facilities that withdraw more than 2 million gallons per day (MGDmgd) of water from 

waters of the U.S.United States and use at least twenty-five (25) percent of the water they 

withdraw exclusively for cooling purposes. These national requirements, which will be 

implemented through National Pollutant Discharge Elimination System (NPDES) 

permits, 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.1

 On April 20, 

2011, EPA published a proposed rule that included several options for addressing these 

impacts. EPA published two Notices of Data Availability (NODA), on June 11, 2012 and 

June 12, 2012, that further clarified EPA’s approach. This final rule constitutes EPA’s 

response to the remand of the Phase II and Phase III rules. In addition, EPA is also 

responding to the decision in Riverkeeper I to remove from the Phase I new facility rule 

 

1

 As noted here, the term BTA means “best technology available for minimizing adverse environmental 

impact.” In the interests of brevity, the acronym will frequently be used in the preamble to reflect the entire 

definition. 
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the restoration-based compliance alternative and the associated monitoring and 

demonstration requirements. 

2. Need for the Rule 

Cooling water is withdrawn for the purpose of dissipating waste heat from 

industrial processes. Over half of all water withdrawn in the United States each year is for 

cooling purposes. By far, the largest industrial use of cooling water is for thermoelectric 

generation, but cooling water is also used in the manufacture of aluminum, chemicals and 

allied products, food and kindred products, pulp and paper, refined petroleum products, 

and steel, as well as in other industries. Although newer designs are more efficient, the 

long life of the capital equipment in these industries suggests that the adverse 

environmental impacts could continue for decades. Electric generators, for example, 

typically convert 30 to 40 percent of the heat content of their fuel to electricity, 

depending on their fuel source, age of their facility, and capacity utilization (see TDD 

5.1). The purpose of cooling water withdrawals is to dissipate that portion of the heat that 

is a by-product of industrial processes that facilities have not used and therefore view as 

waste heat. 

The withdrawal of cooling water by existing facilities removes and kills hundreds 

of billions of aquatic organisms from waters of the United States each year, including 

plankton (small aquatic animals, including fish eggs and larvae), fish, crustaceans, 

shellfish, sea turtles, marine mammals, and many other forms of aquatic life. Most 

impacts are to early life stages of fish and shellfish. Aquatic organisms drawn into CWIS 

are either impinged (I) on components of the intake structure or entrained (E) in the 
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cooling water system itself. In CWA section 316(b) and in this rulemaking, these impacts 

are referred to as adverse environmental impact (AEI). Rates of I&E depend on species 

characteristics, the facility’s environmental setting, and the location, design, construction 

and capacity of the facility’s CWIS. In addition to direct losses of aquatic organisms from 

I&E, a number of indirect, ecosystem-level effects may also occur, including (1) 

disruption of aquatic food webs resulting from the loss of impinged and entrained 

organisms that provide food for other species, (2) disruption of nutrient cycling and other 

biochemical processes, (3) alteration of species composition and overall levels of 

biodiversity, and (4) degradation of the overall aquatic environment. In addition to the 

impacts of a single CWIS on currents and other local habitat features, environmental 

degradation can result from the cumulative impact of multiple intake structures operating 

in the same watershed or intakes located within an area where intake effects interact with 

other environmental stressors. Finally, although it is difficult to measure, the 

compensatory ability of an aquatic population, which is the capacity for a species to 

increase survival, growth, or reproduction rates in response to decreased population, is 

likely compromised by I&E and the cumulative impact of other stressors in the 

environment over extended periods of time.

 The beneficiaries of fish protection at cooling water intakes include fisherman, 

both recreational and commercial, and people interested in well-functioning and healthy 

aquatic ecosystems. While most people consume electricity, they consume electricity in 

differing amounts, and may not be uniformly interested in, or willing to pay for, fish 

protection. Thus, there is imperfect overlap between those who could be required to pay 
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for fish protection and those who would benefit from fish protection. Those who desire 

more fish protection have extremely limited opportunities in which they can express their 

willingness to pay for fish protection in market transactions that result in fish protection. 

In addition, deregulation in the electric industry has made it more difficult for merchant 

power producers to both remain competitive and pass along to consumers costs 

associated with fish protection, relative to rate-regulated electric utilities that are 

vertically integrated.

Fish protection at cooling water intakes is also variable, based on species and their 

migrations, waterbody, size of a cooling water intake, presence of multiple facilities on a 

waterbody, and many more variables that are highly site specific. In addition, given the 

history of litigation around this section of the Clean Water Act, states have, in some 

instances, administratively continued permits while awaiting final Federal action, and 

thus fish protection has been delayed, in some instances for decades. 

Promulgation of today’s final rule will complete EPA’s regulations under section 

316(b) of the Clean Water Act. This rule includes a national performance standard as the 

BTA to address impingement mortality (IM) at existing CWIS. This national standard for 

impingement reflects EPA’s assessment that impingement reduction technology is 

available, feasible and demonstrated, and thus BTA for existing facilities. The 

impingement mortality standard is based on modified traveling screens with fish returns 

and includes a performance standard as one compliance alternative, but also offers six 

other compliance alternatives that are equivalent or better in performance. With regard to 

entrainment, this rule contains a national BTA standard that is a process for a site-specific 
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determination of entrainment mitigation requirements at existing CWIS. The entrainment 

provision reflects EPA’s assessment that there is no single technology basis that is BTA 

for entrainment at existing facilities, but instead a number of factors that are best 

accounted for on a site-specific basis. Site-specific decision making may lead to a 

determination by the NPDES permitting authority that entrainment requirements should 

be based on variable speed pumps, water reuse, fine mesh screens, a closed-cycle 

recirculating system, or some combination of technologies that constitutes BTA for the 

individual site. The site-specific decision-making may also lead to no additional 

technologies being required.

In addition to the above provisions, which apply to existing units at existing 

facilities, the rule establishes a BTA standard, for both impingement mortality 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. 

In addition, there is a need to regulate even those facilities that adopt the most 

effective technology. Cooling water is withdrawn for the purpose of dissipating waste 

heat from industrial processes. Over half of all water withdrawn in the United States each 

year is for cooling purposes. By far, the largest industrial use of cooling water is for 

thermoelectric generation, but cooling water is also used in the manufacture of aluminum, 

chemicals and allied products, food and kindred products, pulp and paper, refined 

petroleum products, and steel, as well as in other industries. Most of these industries are 

capital intensive. The purpose of these withdrawals is to dissipate that portion of the heat 
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that is a by-product of industrial processes that facilities have not harnessed to a 

productive end and therefore view as waste heat. Electric generators typically convert 30 

to 40 percent of the heat content of their fuel to electricity, depending on their fuel 

source, age of their plant, and capacity utilization. Although newer designs are more 

efficient, the long life of the capital equipment in these industries suggests that the 

adverse environmental impacts could continue for decades.Closed-cycle cooling is a 

technology that recirculates cooling water, reducing withdrawals from surface waters. 

Closed-cycle cooling can reduce water withdrawals by upwards of 90at least 95 percent, 

compared to once-through cooling, but is itself capital intensive. Facilities that retrofit to 

closed-cycle cooling without also modifying their condenser may not be able to operate 

at full capacity during summer peak periods of electricity demand (replacing the 

condenser would require longer outages). Thus, even operatorsOperators who retrofit 

closed-cycle cooling systems have a financial incentive not to run their system in closedcycle mode during summer months. Thus, private decision making at facilities that use 

cooling water may not take society’s preferences for fish protection into account in their 

private actions. 

The beneficiaries of fish protection at cooling water intakes include fisherman, 

both recreational and commercial, and citizens interested in well-functioning and healthy 

aquatic ecosystems. While most citizens consume electricity, they consume electricity in 

different amounts, and may not be uniformly interested in, or willing to pay for fish 

protection. Thus, there is imperfect overlap between those who could be required to pay 

for fish protection and those who would benefit from fish protection. Citizens who desire 
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more fish protection have extremely limited opportunities in which they can express their 

willingness to pay for fish protection in market transactions that result in fish protection. 

In addition, deregulation in the electric industry has made it more difficult for merchant 

power producers to both remain competitive and pass along to consumers costs 

associated with fish protection, relative to rate-regulated electric utilities that are 

vertically integrated.

Fish protection at cooling water intakes is also variable, based on species and their 

migrations, water body, size of a cooling water intake, presence of multiple facilities on a 

water body, and many more factors. These factors make it difficult for EPA to issue a 

regulation based on uniform national technology requirements. In addition, given the 

history of litigation around this section of the Clean Water Act, states have, in some 

instances, administratively extended permits, awaiting final federal action, and thus fish 

protection has been delayed, in some instances for decades. EPA notes that some 

facilities have installed, and some NPDES permits require, controls that protect aquatic 

organisms from impingement and entrainment. Facilities may have adopted controls as 

good stewards. Permit directorsDirectors may have required controls to meet state water 

quality standards, particularly with regard to temperature. TheseBased on our evaluation 

of available evidence, these actions have not been widespread enough to discourage 

cooling water withdrawals from waters where they have the greatest impact. With today’s 

rule, EPA is promulgating a rule that will complete the Agency’s regulations under 

Section 316(b) of the Clean Water Act. In response to the adverse environmental impact 

caused by operation of cooling water intake structures, and the fact that private decisions 
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may not account for this impact and thus lead to economic losses in society, EPA is 

promulgating this final rule. This rule includes a national performance standard as the 

best technology available to address impingement mortality at existing CWIS. This 

national standard reflects EPA’s assessment that impingement reduction technology is 

available, feasible and demonstrated, and thus BTA for all existing facilities. In addition, 

this rule contains a national BTA standard for entrainment that is a process for a sitespecific determination of entrainment requirements at existing CWIS. This provision 

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. on 

aquatic organisms. Site-specific decision making may lead to a determination by the 

NPDES permitting authority that entrainment requirements should be based on variable 

speed pumps, water reuse, fine mesh screens, a closed-cycle recirculating system, or 

some combination of technologies that constitutes BTA for the individual site. The sitespecific decision-making may also lead to no additional technologies being required.

In addition to the above provisions, which apply to existing CWIS units at 

existing facilities, the rule establishes a BTA standard for new units at existing facilities. 

New units are defined as newly built, standalone units, or repowered, rebuilt or replaced 

units in which the turbine and condenser are replaced which are not high energy 

efficiency units. 
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3. Costs and Benefits 

As presented in Exhibit I-1, EPA assessed the expected costs to society for 

complying with the final rule as $297 million and $309 million per year, depending on 

the discount rate that is used in the cost calculation. This calculation accounts, accounting

for both the existing CWIS unitsunit provision, and the new unitsunit provision., as $275 

million and $297 million per year at the 3 percent and 7 percent discount rates, 

respectively. These costs reflect permit applications, studies, recordkeeping, monitoring, 

and reporting required by the rule. The costs also include costs of technologies for 

complying with the BTA for IM. The cost of additional technologies that may be required 

to meet the site-specific BTA for entrainment are not included in this analysis because, as 

explained in Section VII, EPA cannot estimate, with any level of certainty, what sitespecific determinations will be made based on the analyses that will be generated as a 

result of the national BTA standard for entrainment decision-making established by 

today’s rule. 

EPA estimates that thetoday’s final rule – including standards for both existing 

units and new units provisionsat existing facilities – will achieve total monetized benefits 

to society of $1933 million and $2129 million annually, again depending on the discount 

rate. This estimate of benefits omits important categories of benefits that EPA expects the 

rule will achieve, such as most of the benefits associated with fish other than 

commercially and recreationally harvested fish. As a result, these estimates are likely to 

understate substantially the rule’s expected benefits to society. In estimating the benefits 

of today’s rule, EPA did not rely on the results of the stated preference survey conducted 
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by the Agency and described in the June 12, 2012 Notice of Data Availability (77 FR 

34927 (June 12, 2012)). Included in the monetized benefits is EPA’s estimate that the 

final rule will reduce greenhouse gas (GHG) emissions by 5.69.3 million tons of 

CO2-equivalent emissions over the 40-year compliance period for this analysis. Based on 

this reduction in GHG emissions, EPA estimates benefits to society (based on social cost 

of carbon) (DCN2 12-4853)) ranging from $512 million to $613 million, annually (see 

Section 9 of the BA), depending on the discount rate and other assumptions in the social 

cost of carbon analysis. 

Exhibit I-1. Total annualized social costs and benefits for the final rule (in millions, 2011 dollars) 

 Existing Units New Units Total 

Using 3 percent discount rate 

Social Costs $272.4 $2.5 $274.9 

Social Benefits $33.0 -$0.2 $32.8 

Using 7 percent discount rate 

Social Costs $295.3 $2.0 $297.3 

Social Benefits $28.7 -$0.1 $28.6 

EPA expects 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 is the industry most affected by today’s rule. Under the rule’s existing unit 

provisionprovisions, EPA estimates that a substantial majority (8486 percent) of Electric 

 

2

 DCN refers to a document control number. An index of DCNs can be found in the docket for this action. 
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Generatorselectric generators will incur compliance costs of less than 1 percent of 

revenue, indicating the minor impact of the rule on these facilities. 

EPA also expects very small impacts on the non-power sector component of 

regulated facilities. EPA estimates that 571504 out of 579509 facilities will incur costs 

less than one percent of revenue, eightfive will incur costs between one and three percent, 

and none will incur costs greater than 3 percent. In addition, EPA estimates that no 

Manufacturersmanufacturing facilities will close as a result of today’s rule, and that only 

12 facilities in the non-power sector component will experience moderate financial stress 

short of closure. These 12 facilities represent approximately 3 percent of the estimated 

total regulated facilities in the non-power sector component. 

At the level of the entities that own regulated facilities, EPA estimates that 91 to 

94 percent of entities owning regulated facilities in the electric power sector will incur 

compliance costs of less than 1 percent of revenue under the rule’s existing unitsunit

provisions. Likewise, for the non-power sector component of regulated facilities, EPA 

estimates that 90 to 95 percent of entities owning regulated facilities will incur 

compliance costs of less than 1 percent of revenue under the rule’s existing unitsunit

provisions. 

Finally, EPA estimates that today’s rule will have a minor impact on the overall 

electric power sector and electricity consumers. EPA estimates that the rule’s existing 

units provisionrule will not affect national or regional electricity markets on a long-term 

basis. In addition, EPA expects there to be no effects of the final rule on the reliability of 

electricity generation, transmission and distribution. In terms of consumer impacts, EPA 
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estimates, on average, across the United States, that the final rule will increase electricity 

production costs by 0.010009 cents per kWh, causing an estimated 0.1 percent increase in 

average electricity prices. The corresponding annual increase in electricity costs is 

approximately $1.1703 per household. 

B. Scope of Today’s Rulemaking 

Today's final rule represents the last stage in EPA’s efforts to implement section 

316(b) of the CWA (Clean Water Act).. In the course of their operations, electric power 

plantsfacilities and certain manufacturing facilities use large amounts of water either for 

cooling purposes or in their manufacturing processes. Such facilities typically remove 

water from nearby sources using “cooling water intake structures.” The structures 

associated with water removal pose a number of threats to the environment. Principally, 

aquatic organisms are squashed against intake screens – impingement – or drawn into the 

cooling system – entrainment. Section 316(b) requires EPA to develop standards for 

cooling water intakes structures. 

Today’s final rule establishes national requirements applicable to the location, 

design, construction, and capacity of cooling water intake structures at existing facilities 

that reflect the best technology availableBTA for minimizing the adverse environmental 

impact (BTA)–impacts– impingement and entrainment – associated with the use of these 

structures. It represents the culmination of EPA’s efforts to implement section 316(b) 

and, as such, fulfills EPA's obligation under a settlement agreement entered in the United 

States District Court for the Southern District of New York in Riverkeeper Inc., et al. v. 
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Jackson, No. 93 Civ. 0314 (AGS). (For a more detailed discussion of the settlement 

agreement, see Section II.C.) 

This final rule establishes requirements for all existing facilities with a DIF 

(design intake flow) of more than 2 mgd (million gallons per day).. EPA estimates that a 

total of 1,065 facilities will be subject to the final rule, including 544 Electric Generators, 

509 Manufacturers in six Primary Manufacturing Industries, and 12 Manufacturers in 

Other Industries. The rule also clarifies the definition and requirements for new units at 

existing facilities. The applicable requirements are summarized in Exhibits I-12 and I-23. 

Exhibit I-12. Applicability by phase of the 316(b) rules 

Facility characteristic Applicable rule 

New power-generating or manufacturing facility Phase I rule 

New offshore oil and gas facility Phase III rule 

New unit at an existing power-generating or manufacturing facility This rule 

Existing power-generating or manufacturing facility This rule 

Existing offshore oil and gas facility and offshore seafood processing 

facilities 

This rule (site-specific, 

BPJ) 

Exhibit I-23. Applicable requirements of today’s rule for existing facilities 

Facility characteristic Applicable requirements 

Existing facility with a DIF greater than 2 mgd and 

an AIF (actual intake flow) greater than 125 mgd 

Impingement mortality standards at § 125.94(c) and 

site-specific entrainment requirements under the 

entrainment standards at § 125.94(d) (Additional 

study requirements at § 122.21(r)(1)(ii)(B)) 

Existing facility with a DIF greater than 2 mgd but 

AIF not greater than 125 mgd 

Impingement mortality standards at § 125.94(c) ) 

and site-specific entrainment requirements under 

the entrainment standards at § 125.94(d) 

New unit at an existing facility where the facility has 

a DIF greater than 2 mgd 

Impingement mortality standards at § 125.94(c) and 

new unit entrainment standards for new units at § 

125.94(e) 
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Other existing facility with a DIF of 2 mgd or smaller 

or that has an intake structure that withdraws less 

than 25 percent of the water for cooling purposes 

on an actual intake flow basis 

Site-specific, BPJCase-by-case BPJ permitting per § 

125.90(b)

At an early stage in the development of section 316(b) requirements, EPA divided 

its rulemaking effort into three phases. The first addressed new facilities, the second, 

large existing electricity utility facilities and the third, the remaining electric generating 

facilities not addressed in the earlier phases as well as existing manufacturing operations. 

As EPA’s analysis progressed, however, it became clear that it could address in one 

rulemaking cooling water intake structures at both existing steam electric generating and 

manufacturing facilities. From a biological perspective, the effect of intake structures on 

impingement and entrainment3

 does not differ depending on whether an intake structure 

is associated with a power plant or a manufacturer. In 2009, following judicial challenge 

of the Phase II rule, EPA asked the U.S. Court of Appeals for the Second Circuit to 

remand the rule to the Agency for further action consistent with a decision by the U.S. 

Supreme Court in Entergy Corp. v. Riverkeeper, Inc. and the Second Circuit’s decision 

on the Phase II rule in Riverkeeper, Inc. v. EPA, 475 F.3d 83 (2d cir. 2007). In 2009, EPA 

also asked the U.S. Court of Appeals for the Fifth Circuit to remand certain aspects of 

EPA’s Phase III rule that were before it in a petition for review. Today’s rule responds to 

 

3

 Throughout the preamble and support documents, the terms “entrainment” and “entrainment mortality” 

may be used interchangeably. As described below, EPA continues to assume that, in most instances, 

entrainment mortality is 100%, percent, leaving little distinction between the two terms. 
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these remands as well to the Second Circuit’s remand of limited aspects of the Phase I 

section 316(b) rule in Riverkeeper Inc. v. Johnson, 358 F.3d 174 (2nd Cir. 2004). EPA 

has here consolidated the universe of potentially regulated facilities from the remanded 

2004 Phase II rule with the existing facilities in the remanded 2006 Phase III rule for 

establishing requirements in a single proceeding.

C. General Applicability 

This rule applies to owners and operators of existing facilities4 that meet all 

following criteria: 

 The facility is a point source that uses or, in the case of a new unitunits at an 

existing facility, proposes to use cooling water from one or more cooling water 

intake structures, including a cooling water intake structure operated by an 

independent supplier not otherwise subject to 316(b) requirements that withdraws 

water from waters of the United States and provides cooling water to the facility 

by any sort of contract or other arrangement; 

 The facility-wide DIF for all cooling water intake structures at the facility is 

greater than 2 mgd; 

 The cooling water intake structure withdraws cooling water from waters of the 

United States; and 

 

4

 Throughout the preamble, the terms “owner or operator of a facility” and “facility” may be used 

interchangeably. In cases where the preamble may state that a facility is required to do a given activity, it 

should be interpreted as the the owner or operator of the facility is required to do the activity. 
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 At least 25 percent of the water actually withdrawn --– actual intake flow (AIF) --

– is used exclusively for cooling purposes. 

A facility may choose to demonstrate compliance with the final rule for the entire 

facility, or for each individual cooling water intake structure. 

EPA is adopting provisions that promote the reuse of water from certain sources 

for cooling and that ensure that the rule does not discourage the reuse of cooling water for 

other uses such as process water. For example, the final rule at § 125.91(c) specifies that 

obtaining cooling water from a public water system, using reclaimed water from 

wastewater treatment facilities or desalination plants, or recycling treated process 

wastewater effluent (such as wastewater treatment plant “gray” water) does not constitute 

use of a cooling water intake structure for purposes of this rule. In addition, the definition 

of cooling water at § 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 isas process water is not

considered processcooling water for the purposes of calculating the percentage of a 

facility’s intake flow that is used for cooling purposes. Therefore, water used for both 

cooling and non-cooling purposes does not count toward the 25 percent threshold. 

Examples of water withdrawn for non-cooling purposes includes water withdrawn for 

warming by LNG (liquefied natural gas) facilities and water withdrawn for public water 

systems by desalinization facilities. 
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Today’s rule focuses on those facilities that are significant users of cooling water. 

The rule provides that only those facilities that use more than 25 percent or more of the 

water withdrawn exclusively for cooling purposes (on an actual intake flow basis) are 

subject to the rule. EPA previously considered a number of cut-points or approaches for 

focusing the applicability of the rule (66 FR 28854 [, May 25, 2001] and 66 FR 65288 [, 

December 18, 2001]).). EPA used the 25 percent threshold in each of the Phase I, II, and 

III rules. For this rule, EPA did not receive any new data supporting a different threshold 

or identify new approaches to the applicability of the rule. Consequently, EPA is 

adopting 25 percent as the threshold for the percent of flow used for cooling purposes to 

ensure that a large majority of cooling water withdrawn from waters of the United States 

are subject to the rule’s requirements for minimizing adverse environmental impact. 

Because power-generating facilities typically use far more than 25 percent of the water 

they withdraw exclusively for cooling purposes, the 25 percent threshold will ensure that 

intake structures accounting for nearly all cooling water used by the power sector are 

addressed by today’s rule requirements. While manufacturing facilities often withdraw 

water for more purposes than cooling, the majority of the water is withdrawn from a 

single intake structure. Once water passes through the intake, water can be apportioned to 

any desired use, including uses that are not related to cooling. However, as long as at 

least 25 percent of the water is used exclusively for cooling purposes, the intake is subject 

to the requirements of today’s rule. EPA estimates that approximately 6870 percent of 

manufacturers and 9387 percent of power-generating facilities that meet the first three 

criteria for applicability outlined above also use more than 25 percent or more of intake 
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water for cooling and thus are subject to today’s rule. (See 66 FR 65288, December 18, 

2001.) 

For facilities that are below any of the applicability thresholds in today’s rule, –

for example, a facility that withdraws less than 25 percent of the intake flow for cooling 

purposes, – the Director must set appropriate requirements on a site-specificcase-by-case 

basis, using best professional judgment (BPJ) , based on § 125.90(b). Today’s rule is not 

intended to constrain permit writers at the Federal, State, or Tribal level, from addressing 

such cooling water intake structures. Also, EPA decided to adopt for the final rule the 

proposed provision that requires the owners and operators for certain categories of 

facilities (existing offshore oil and gas facilities, existing offshore seafood processing 

facilities and offshore LNG terminals) to meet site-specificcase-by-case BTA 

impingement and entrainment requirements, established by the Director. Such facilities 

are subject to permit conditions implementing CWA section 316(b) if the facility is a 

point source that uses a cooling water intake structure and has, or is required to have, an 

NPDES permit. 

D. What is an “Existing Facility” for Purposes of the Final Rule? 

In today’s rule, EPA is defining the term “existing facility” to include any facility 

subject to section 316(b) that is not a “new facility” as defined in 40 CFR 125.83. (the 

Phase I rule).
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A point source discharger would be subject to Phase I or today’s rule even if the 

cooling water intake structure it uses is not located at the facility.5

 In addition, 

modifications or additions to the cooling water intake structure (or even the total 

replacement of an existing cooling water intake structure with a new one) does not 

convert an otherwise unchanged existing facility into a new facility, regardless of the 

purpose of such changes (e.g., to comply with today’s rule or to increase capacity). 

Rather, the determination as to whether a facility is new (Phase I) or existing (today’s 

rule) focuses on whether or not it is a greenfield or stand-alone facility whose processes 

are substantially independent of an existing facility, and whether or not there are changes 

to the cooling water intake. New facility does not include new units that are added to 

accommodate it.a facility for purposes of the same general industrial operation. For 

example, a new peaking unit at an existing electrical generating station is not a new 

facility (40 CFR 125.83). The distinction between an existing facility and a new facility 

is separate from the distinction between an existing unit at an existing facility and a new 

unit at an existing facility, which is discussed at greater length in Section J below. 

E. What is “Cooling Water” and What is a “Cooling Water Intake Structure?” 

EPA has notslightly revised the definition of cooling water intake structure from 

proposal for today’s rule. AIn today’s final rule, a cooling water intake structure is 

defined as the total physical structure and any associated constructed waterways used to 

 

5

 For example, a facility might purchase its cooling water from a nearby facility that owns and operates a 

cooling water intake structure. 
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withdraw cooling water from waters of the United States. Under the definition in today’s 

rule, the cooling water intake structure extends from the point at which water is first 

withdrawn from Waters of the surface water sourceUnited States up to, and including, the 

intake pumps. The final rule at § 125.91(c) also specifies that obtaining cooling water 

from a public water system, using reclaimed water from wastewater treatment facilities 

(such as wastewater treatment plant “gray” water) or desalination plants, or recycling 

treated process wastewater effluent (such as wastewater treatment plant “gray” water) 

does not constitute use of a cooling water intake structure for purposes of applicability 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 

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. 

Today’s rule adopts the new facility rule’s definition of cooling water as water 

used for contact or noncontact cooling, including water used for equipment cooling, 

evaporative cooling tower makeup, and dilution of effluent heat content. The definition 

specifies that the intended use of cooling water is to absorb waste heat [not being 

efficiently used or recaptured for production and thus] rejected from the process or 

processes used or from auxiliary operations on the facility’s premises. The definition also 
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indicates 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, or is as process water would not be considered 

cooling water for the purposes of determining whether 25 percent or more of the actual 

intake flow is cooling water. This clarification is necessary because cooling water intake 

structures typically bring water into a facility for numerous purposes, including industrial 

processes; use as circulating water, service water, or evaporative cooling tower makeup 

water; dilution of effluent heat content; equipment cooling; and air conditioning. Note, 

however, that all intake water (including cooling and non-cooling process) is included in 

the determination as to whether the 2 mgd DIF threshold for covered intake structures is 

met. 

F. Would My Facility Be Covered Only If It Is a Point Source Discharger? 

Today’s rule applies only to facilities that have an NPDES permit or are required 

to obtain one. This is the same requirement EPA included in the Phase I new facility rule 

at § 125.81(a)(1). Requirements for complying with CWA section 316(b) will continue to 

be applied through NPDES permits. 

On the basis of the Agency’s review of potential existing facilities that employ 

cooling water intake structures, the Agency anticipates that most facilities will control the 

intake structure that supplies them with cooling water, and discharge some combination 

of their cooling water, wastewater, or stormwater to a water of the United States through 

a point source regulated by an NPDES permit. In such cases, the facility’s NPDES permit 
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must include the requirements for the cooling water intake structure. If an existing 

facility’s only NPDES permit is a general permit for stormwater discharges, the Agency 

anticipates that the Director will write an individual NPDES permit containing 

requirements for the facility’s cooling water intake structure. Alternatively, requirements 

applicable to cooling water intake structures could be incorporated into general permits. 

If requirements are placed into a general permit, they must meet the requirements set out 

at 40 CFR 122.28. 

As EPA stated in the preamble to the final Phase I rule (66 FR 65256, December 

18, 2001), the Agency encourages the Director to closely examine scenarios in which a 

facility withdraws significant amounts of cooling water from waters of the United States 

but is not required to obtain an NPDES permit. As appropriate, the Director must apply 

other legal requirements, where applicable, such as CWA sections 401 or 404, the 

Coastal Zone Management Act, the National Environmental Policy Act, the Endangered 

Species Act, or similar State or Tribal authorities to address adverse environmental 

impact caused by cooling water intake structures at those facilities. 

G. Would My Facility Be Covered If It Withdraws Water from Waters of the 

United States? What If My Facility Obtains Cooling Water from an Independent 

Supplier? 

The requirements in today’s rule apply to cooling water intake structures that have 

the design capacity to withdraw amounts of water greater than 2 mgd from waters of the 

United States. Waters of the United States include the broad range of surface waters that 

meet the regulatory definition at 40 CFR 122.2 and 40 CFR 230.3, which includes lakes, 
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ponds, reservoirs, nontidal rivers or streams, tidal rivers, estuaries, fjords, oceans, bays, 

and coves. These potential sources of cooling water can be adversely affected by 

impingement and entrainment. 

Some facilities use an impoundment such as a man-made pond or reservoir as part 

of theira cooling system. Cooling water is withdrawn from the pond or reservoir at one 

point and heated water is discharged to a different point, using mixing and evaporative 

processes. These impoundments can be closed systems if the pond or reservoir was not 

constructed by impounding a water of the U.S. In these cases impoundments may 

constitute a closed-cycle cooling system and therefore might already comply with some 

of or all the technology-based requirements in today’s rule. However, facilities that 

withdraw cooling water from impoundments that areAs explained above, section 316(b) 

and today’s final rule apply only to withdrawals of cooling water from waters of the 

United States; accordingly, to the extent a facility withdraws cooling water from a pond 

or reservoir that is not itself a water of the United States and does not withdraw any 

make-up water from waters of the U.S., the requirements of today’s rule do not apply to 

such systems. Impoundments that are not constructed from a waters of the U.S. but do 

withdraw make-up water from waters of the U.S. can be closed-cycle recirculating 

systems subject to the requirements of today’s rule, provided that withdrawal for makeup water is minimized. 

Facilities that withdraw cooling water from impoundments that are in whole or in 

part waters of the United States and that meet the other criteria for coverage (including 

the requirement that the facility has or will be required to obtain an NPDES permit) are 
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subject to today’s rule. In some cases, water is withdrawn from a water of the United 

States to provide make-up water for the impoundment.In today’s rule, the agency is 

defining the term closed-cycle recirculating system to include, at § 125.92(c)(2), a system 

with impoundments of waters of the U.S. where the impoundment was lawfully created6

for the purpose of serving as part of the cooling water system. In determining whether an 

impoundment qualifies as a closed-cycle recirculating system, the Director will determine 

whether the make-up water withdrawals for such a system have been minimized. In 

many cases, EPA expects that such make-up water withdrawals are commensurate with 

the flows of a closed-cycle cooling tower, and again the facility might already comply 

with requirements to reduce its intake flow under the rule. In those cases where the 

withdrawals of make-up water come from a water of the United States, and the facility 

otherwise meets today’s criteria for coverage (including a DIF of greater than 2 mgd), the 

facility will be subject to today’s rule requirements. Some of these impoundments may 

qualify for the waste treatment exclusion found in the definition of a waste treatment 

system at 40 CFR 122.2, and this rule does not affect the applicability of that exclusion. 

EPA does not intend for this rule to change the regulatory status of 

impoundments. Impoundments are neither categorically included nor categorically 

 

6

 The owner or operator of the facility would provide documentation such as the project purpose statement 

for the Clean Water Act section 404 permit obtained to construct the impoundment. If the impoundment 

was created prior to the CWA requirement to obtain a section 404 permit, the owner or operator would 

provide any other license or permit obtained to lawfully construct the impoundment for the purposes of a 

cooling water system. 
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excluded fromaddressed in the definition of waters of the United States at 40 CFR 122.2

and 40 CFR 230.3. The determination whether an impoundment is a water of the United 

States is to be made by the Director on a site-specific basis. The EPA and the U.S. Army 

Corps of Engineers have jointly issued jurisdictional guidance concerning the term waters 

of the United States in light of the Supreme Court’s decision in Solid Waste Agency of 

Northern Cook County v. U.S. Army Corps of Engineers, 531 U.S. 159 (2001) 

(SWANCC). A copy of that guidance was published as an Appendix to an Advanced 

Notice of Proposed Rulemaking on the definition of the phrase waters of the United 

States, see 68 FR 1991, January 15, 2003, which is at 

http://www.epa.gov/owow/wetlands/pdf/ANPRM-FR.pdf. The agencies additionally 

published guidance in 2008 regarding the term waters of the United States in light of both 

the SWANCC and subsequent Rapanos case (Rapanos v. United States, 547 U.S. 715 

(2006)). The EPA published a proposed revision to the definition of “Waters of the 

United States” under the Clean Water Act on April 21, 2014 (see 79 FR 22188).

EPA recognizes that some impoundments may be man-made waterbodies that 

support artificially managed and stocked fish populations. As a result, EPA has included 

a provision in today’s final rule to allow the Director to waive certain permit application 

requirements for such facilities. Note, however, that these facilities are still subject to the 

final rule. 

EPA acknowledges that the point of compliance for facilities located on 

impoundments may also vary depending on whetherwhere the facility withdraws from a 

water of the United States. As suchAgain, only cooling water systems with withdrawals 
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of cooling water from waters of the United States are covered by section 316(b) and 

today’s rule. Because a facility may withdraw cooling water from a water of the United 

States either directly or as makeup water for a closed-cycle cooling system, the Director 

may impose requirements at the determine where within a facility’s main cooling water 

intake structure or at its makeup water withdrawal intake.is or are the facility’s point or 

points of compliance. 

The Agency recognizes that some facilities that have or are required to have an 

NPDES permit might not own and operate the intake structure that supplies their facility 

with cooling water. In addressing facilities that have or are required to have an NPDES 

permit that do not directly control the intake structure that supplies their facility with 

cooling water, § 125.91 provides (similar to the new facility rule) that facilities that 

obtain cooling water from a public water system, use reclaimed water from a wastewater 

treatment facility or desalinization plant, or use treated effluent are not deemed to be 

using a cooling water intake structure for purposes of this rule. However, obtaining water 

from another entity that is withdrawing water from a water of the United States will be 

counted as using a cooling water intake structure for purposes of determining whether an 

entity meets the threshold requirements of the rule. For example, facilities operated by 

separate entities might be located on the same, adjacent, or nearby property. One of these 

facilities might take in cooling water and then transfer it to other facilities that discharge 

to a water of the United States. Section 125.91(b) specifies that use of a cooling water 

intake structure includes obtaining cooling water by any sort of contract or arrangement 

with one or more independent suppliers of cooling water if the supplier or suppliers 
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withdraw water from waters of the United States but that is not itself a new or existing 

facility subject to CWA section 316(b), except if it is a public water system, a wastewater 

treatment facility or desalination plant providing reclaimed water, or a facility providing 

treated effluent for reuse as cooling water pursuant to § 125.91(c).

As a practical matter, the existing facilities subject to this rule are the largest users 

of cooling water and therefore typically require enoughwithdraw volumes of water for

cooling water tothat warrant owning the cooling water intake structures. In some cases, 

such as at nuclear power plants or critical baseload facilities, the need for cooling water 

includes safety and reliability reasons that would likely preclude any independent 

supplier arrangements. Therefore, EPA expects this provision will have only limited 

applicability. EPA is nevertheless retaining the provision to prevent facilities from 

circumventing the requirements of today’s rule by creating arrangements to receive 

cooling water from an entity that is not itself subject to today’s rule and that is not 

otherwise explicitly exempt from today’s rule(such as drinking water or treatment plant 

discharges reused as cooling water). 

H. What Intake Flow Thresholds Result in an Existing Facility Being Subject to 

the Final Rule? 

EPA determines the cooling water flow at a facility in two ways. The first way is 

based on the DIF, which reflects the maximum intake flow the facility is capable of 

withdrawing. While this normally is limited by the capacity of the cooling water intake 

pumps, other parts of the cooling water intake system could impose physical limitations 

on the maximum intake flow the facility is capable of withdrawing. The second 
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waymethod for determining cooling water flow is based on the AIF, which reflects the 

actual volume of water withdrawn by the facility. EPA has defined AIF to be the average 

water withdrawn each year over the preceding three calendar years.7

 Both of these 

definitionsmethods are used in today’s rule. 

In this rule, EPA considered requirements based on the intake flow at the existing 

facility. Today’s final rule applies to facilities that have a total design intake capacityDIF

of greater than 2 mgd (see § 125.91).8 At a threshold of 2 mgd, today’s rule covers 99.78

percent of the total water withdrawals by utilities and other industrial sources (if the other 

criteria for coverage are met), including 58which includes 70 percent of the 

manufacturing facilities, 70 percent of the non-utility facilities, and 100 87 percent of the 

utility facilities.9electric generators. EPA also chose the greater than 2 mgd threshold 

because it was consistent with the applicability criteria in the Phase I rule.10 EPA has 

concluded that this threshold ensures that the users of cooling water causing the most 

adverse environmental impact will be subject to the rule.

There are substantial environmental benefits that will accrue with a threshold of 2 

mgd. For example, EPA's analysis indicates that greater than 82 percent of impinged fish 

 

7

 For permit terms subsequent to the first permit issued under today’s rule, the rule defines AIF as the 

average flows over the 5 years in the previous permit term5 years. 8

 The 2004 Phase II rule would have applied to existing power-generating facilities with a design intake 

flow of 50 mgd or greater. Facilities potentially regulated by the Phase III rule had a DIF of greater than 2 

mgd. 

9

 Utilities are regulated entities that provide electricity at a set price and typically include generation and 

transmission capabilities. Non-utilities produce power primarily for themselves or for sale to utilities. 

10 For more information, see 65 FR 49067/3, August 10, 2000. 
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mortality across all facilities would be prevented by this rule at this threshold. EPA also 

considered a threshold of 50 mgd. The record includes 38 studies documenting IM at 

more than 40 facilities with flows lower than 50 mgd. 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 intake flows greater than 50 mgd. In 

addition, lower intake flow facilities can have similar impacts to those of larger flow 

facilities as sizable numbers of fish are impinged by lower flow facilities. Moreover, sitespecific impacts of lower flow facilities may be significant, particularly where threatened 

or endangered species are present. 

Although smaller flow facilities (those less than 50 mgd) constitute a large 

proportion of the total number of the facilities regulated (476 of 1,065), the total 

compliance cost for these smaller facilities are only a small portion of the total 

compliance cost of the rule ($23 million of $275 million). Thus any perceived aggregate 

cost savings from setting the threshold higher than 2 mgd would be minimal. 

There is no appreciable difference in the cost effectiveness of the rule with a 

higher applicability threshold. For example, the cost effectiveness of the rule with a 

threshold of 2 mgd is $0.42 per age-one equivalent losses (A1E). At a threshold of 50 

mgd the cost effectiveness would be $0.41 per A1E. In addition, the incremental cost of 

the 2 mgd threshold relative to a 50 mgd threshold is negligible for the electric power 

industry at less than 0.1 percent of annual electricity sector revenue, which exceeds $126 

billion. The facility-level impacts are negligible to zero at either 2 or 50 mgd threshold. 

At the 2 mgd threshold, only 5 (1 percent) of the manufacturing facilities have a cost-to 
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revenue ratio exceeding 1 percent (but less than 3 percent). While this drops to zero 

facilities at the 50 mgd threshold, the difference of 5 facilities out of 509 facilities is not 

significant. Costs for lower flow facilities are so small that the average annual household 

utility bill would not measurably decrease by changing the threshold from 2 to 50 mgd. 

While 58 percent of the small facilities affected by the final rule are below 50 mgd, 40 

percent of them already meet one of the compliance alternatives for impingement 

mortality of the rule and likely would not need to install any additional compliance 

technologies. And small businesses account for only 17 percent of facilities at or below 

50 mgd, demonstrating that there would not be a disproportionate impact on small 

businesses at a 2 mgd threshold. 

Thus, EPA concluded that the threshold of 2 mgd ensures that the users of cooling 

water causing the most adverse environmental impact are subject to the rule. Raising the 

threshold for applicability of the rule’s impingement and entrainment requirements to 50 

mgd as some commenters suggested was not supportable given the statistics and 

information described above. 

Raising the applicability threshold to 50 mgd would have meant that 476 

facilities, almost half of the 1,065 facilities subject to the national standards set by 

today’s rule, would not be subject to the rule. Ignoring so many facilities when setting 

national standards fails to apply the common sense approaches set forth in this rule for 

minimizing adverse environmental impacts from cooling water intake structures. 

Excluding such a large number of facilities from this rule would create regulatory 

uncertainty for those facilities since they would remain subject to CWA permitting 
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requirements, but without the benefits of the structure of this rule. Directors would have 

an obligation to establish controls on a case-by-case basis for these lower flow facilities 

using a BPJ analysis instead of using the more straightforward and transparent provisions 

of setting controls based on national standards contained in this rule. Such BPJ analyses 

can be uncertain, and can be time consuming and complex to develop for both Directors 

and owners and operators of facilities. Case-by-case BPJ permits (instead of permits 

based on the national standards in today’s rule) would likely increase the time and costs 

to states for such permits to be developed, further delaying the minimization of adverse 

environmental impacts called for by CWA section 316(b). Maintaining an applicability 

threshold of 2 mgd DIF best combines the shared goals of minimizing adverse 

environmental impacts as required by the CWA, and the predictability and flexibility 

contained in the rule. 

EPA acknowledges that there may be circumstances where flexibility in the 

application of the rule may be called for and the rule so provides. For example, some low 

flow facilities that withdraw a small proportion of the mean annual flow of a river may 

warrant special consideration by the Director. As an illustration, if a facility withdraws 

less than 50 mgd AIF, withdraws less than 5 percent of mean annual flow of the river on 

which it is located (if on a river or stream), and is not co-located with other facilities with 

CWISs such that it contributes to a larger share of mean annual flow, the Director may 

determine that the facility is a candidate for consideration under the de minimis 

provisions contained at § 125.94(c)(11). In the case of facilities on lakes and reservoirs, 
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co-location would be better determined by multiple CWIS facilities on the same 

waterbody, rather than distance. 

In either case, the flexibilities contained in the rule for the Director to consider the 

site-specific characteristics of each intake structure within the national standard provide a 

useful mechanism for facilities with lower intake flows and low impacts to be considered. 

EPA is continuing to base applicability on DIF as opposed to AIF for several 

reasons. In contrast to AIF, DIF is a fixed value based on the design of the facility’s 

operating system and the capacity of the circulating and other water intake pumps. This 

provides clarity because the DIF does not vary with facility operations, except in limited 

circumstances, such as when a facility undergoes major modifications. On the other hand, 

actual flows can vary significantly over sometimes short periods. For example, a peaking 

power plant might have an AIF close to the DIF during times of full energy production, 

but an AIF of zero during lengthy periods of standby. Use of DIF provides clarity as to 

regulatory status, is indicative of the potential magnitude of environmental impact, and 

avoids the need for monitoring to confirm a facility’s status. For more information about 

these thresholds, see 69 FR 41611, July 9, 2004. 

Under this rule, all facilities with a DIF of greater than 2 mgd, that meet the other 

three criteria for applicability of today’s rule, must submit basic information describing 

the facility, source water physical data, source water biological characterization 

dataSource Water Physical Data, Source Water Biological Characterization Data, and 

cooling water intake system dataCooling Water Intake System Data. In addition, these 

facilities must submit additional facility-specific information including the selected 
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impingement compliance option, and operational status of each of the facility’s units.11

Certain facilities withdrawing the largest volumes of water for cooling purposes have 

additional information and study requirements such as relevant biological survival studies 

and the Entrainment Characterization Studyentrainment study as described below. 

The final rule uses AIF rather than DIF for purposes of determining which 

facilities must provide the information required in § 122.21(r)(9)-(13), including an 

Entrainment Characterization Study.) through (13), referred to as the entrainment study.

Thus, the rule provides that any facility subject to the rule with actual flows in excess of 

125 mgd must provide an entrainment study with its permit application (which includes 

the Entrainment Characterization Study with its permit application.at § 122.21(r)(9)).12

Adverse environmental impacts from entrainment result from actual water withdrawals, 

and not the maximum designed level of withdrawal. Further, using actual flow might 

encourage some facilities to adopt operational practices to reduce their flows below 125 

mgd AIF to avoid collecting supplemental data and submitting the additional entrainment 

characterization study. Furthermore, any facility that has DIF greater than 2 mgd, that 

meets the other three criteria for applicability of today’s rule, is required to submit basic 

 

11 The final rule contains streamlinedallows the Director to waive certain information submission 

requirements for facilities that already employ closed-cycle cooling. 

12 For impoundments constructed in uplands or not in waters of the United States, the point of compliance 

for measuring AIF to determine if it is greater than 125 mgd is the intake into the impoundment from the 

waters of the United States. 
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information that will allow the Director to verify its determination of whether it meets the 

125 mgd AIF threshold. 

EPA has selected aan administrative threshold of 125 mgd AIF for submission of 

the Entrainment Characterization Study (as well as studies described at § 122.21(r)((7) 

and (10)-(13))entrainment study because this threshold will capture 90 percent of the 

actual flows but will apply to only 30 percent of existing facilities. ThisFurther, based on 

EPA’s data there are no closed-cycle recirculating systems in use above this threshold. 

The 125 mgd AIF threshold will significantly limit facility burden at more than twothirds of the potentially affected facilities while focusing the Director on major cooling 

water withdrawals. Contrary to a number of public comments, however, EPA is not 

implying or concluding that the 125 mgd threshold is an indicator that facilities 

withdrawing less than 125 mgd are (1) not causing any adverse impacts or (2) 

automatically qualify as meeting BTA. In other words, the threshold, while justified on a 

technical basis, does not result in exemptions from the rule. Instead, EPA is making a 

policy decision onas to which facilities must provide a certain level and type of 

information. The Director, of course, will retain the discretion to require reasonable 

information to make informed decisions at the smaller facilities. The 125 mgd threshold

is simply an administrative cutoff that focuses on the facilities with the highest intake 

flows and the highest likelihood of causing adverse impacts; it is not an indicator that 

facilities under that threshold are no longer of concern in the final rule. 

In today’s rule, EPA seeks to clarify that for some facilities, the DIF is not 

necessarily the maximum flow associated with the intake pumps. For example, a power 
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plant might have redundant circulating pumps, or might have pumps with a name plate 

rating that exceeds the maximum water throughput of the associated piping. EPA intends 

for the DIF to reflect the maximum rate at which a plantfacility can physically withdraw 

water from a source waterbody (usually normalized to a daily rate in mgd). This also 

means that a plantfacility that has permanently taken a pump out of service should be 

able to consider such constraints when reporting its DIF, as the facility’s capacity to 

withdraw water may have fundamentally changed. Additionally, if a facility’s flow is 

limited by constrictions in the piping or other physical limitations (e.g., a given portion of 

its cooling system that can only safely handle a given amount of flow) and that flow is 

lower than the DIF for the pumps, the facility should be able to consider such constraints 

when reporting its DIF, because it is not capable of withdrawing its full pumping DIF 

without compromising the cooling system. 

I. What are the Requirements for Existing Offshore Oil and Gas Facilities, 

Offshore Seafood Processing Facilities or LNG Terminals BTA Requirements under 

the Final Rule?

Under today’s rule, existing offshore oil and gas facilities, existing offshore 

seafood processing facilities and existing LNG terminals will be subject to section 316(b) 

requirements on a BPJ basis. In the Phase III rule, EPA studied offshore oil and gas 
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facilities and offshore seafood processing facilities13 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.14 As discussed in the 

Phase III rule, 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 intake flow basis. EPA has not identified 

a uniformly applicable and available technology for minimizing impingement mortality 

and entrainment at these facilities. However, technologies might be available for some 

 

13 EPA studied naval vessels and cruise ships as part of its developing a general NPDES permit for 

discharges from oceangoing vessels. (For more information, see 

http://cfpub.epa.gov/npdes/home.cfm?program_id=350.) EPA studied offshore seafood processing facilities 

and oil and gas exploration facilities in the 316(b) Phase III rule. 

14 As discussed in today’s preamble, requirements for new offshore facilities that were set forth in the Phase 

III rule remain in effect. 
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existing LNG facilities. LNG facilities that withdraw any volume of water for cooling 

purposes will be subject to site-specific, BPJ BTA determinations of BTA. 

EPA has not identified any new data or approaches that would result in a different 

determination. Therefore, EPA has adopted the approach of the proposed rule and is 

requiring that NPDES permit directorsPermit Directors, on a site-specificcase-by-case

basis using BPJ, determine BTA for existing offshore oil and gas extraction facilities and, 

existing offshore seafood processing facilities, and existing LNG terminals. 

J. What is a “New Unit” and How Are New Units Addressed Under the Final 

Rule? 

Today’s rule establishes requirements for new units at an existing facility that are 

different than the requirements that otherwise applythose applicable to existing units at an 

existing facility. The requirements for new units at existing facilities are modeled after 

the requirements for a new facility in the Phase I rule. Today’sUnder today’s rule

clarifies that , a “new unit” means a newly built, stand-alone unit, whose construction 

begins after the effective date of the rule. EPA is also clarifying that while Phase I does 

not include certain limited upgrades to units newly constructed at an existing unit. 

Instead,facility for the same general industrial operation, such units do constitute a new 

unit does mean the addition of a newly built, stand-alone unit or the modification of anat

existing unit that is repowered or undergoes significant modification such that both the 

turbinefacilities and condenser, as such, are replaced, except that the addition or 

modification of an existing unit to replace it with a high energy efficiency unit is not 

defined as a new unit. subject to today’s final rule.
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On the basis of the public comments received on how to define “new units (and 

repowering),unit,” EPA has sought to provideprovides a clear definition for these 

termsthis term in the final rule. In EPA’s view, these definitionsThe definition for a new 

unit at an existing facility establishestablishes a clear regulatory framework for both 

affected facilities and Directors. ItThis definition captures facilities that are undergoing 

major construction projects involving the construction of a new stand-alone unit, while 

not discouraging upgrades or the construction of new/replacement units.. For example, a 

nuclear facility conducting a measurement uncertainty capture or a stretch power uprate, 

or a fossil-fuel facility repowering an existing generating unit, would not be considered to 

result in the relevant unit becoming a new unit. As another example, under this definition 

placing an offshore facility or vessel into a dry dock for maintenance or repair does not 

result in either the offshore facility, vessel, or the dry dock as being defined as a new unit. 

Section VI discusses EPA’s rationale for establishing the definitions for new units 

at existing facilities described below. A definition for high energy efficiency units is also 

provided in Section VI.

1. Electric Generators 

The final rule defines two types of units as a a new unit at an existing facility. 

First, as a newly built, stand-alone unit (i.e., a unit where a new condenser and turbine are 

built) that is constructed at an existing facility (and that does not meet the definition of a 

new facility) will be defined as a new unit. Second, an. An existing unit that is repowered 

or undergoes significant modifications (to a degreesuch as where both the turbine and 

condenser are replaced) will also beis not considered a new unit at an existing facility, 
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except where replaced with high energy efficiency units. High energy efficiency units are 

those that use less fuel, measured as BTU (British thermal units), to produce a kWh 

(kilowatt hour) of electricity. The definition of high energy efficiency units at § 125.92 

includes a numeric threshold for high energy efficiency. Under the second category, 

several types of modifications will not lead to considering the unit as a new unit, thereby 

defining the unit as an existing unit. In such cases, the existing unit will be regulated 

under the existing unit provisions of this rule, and the unit will not be subject to 

categorical requirements to reduce intake flow to a level commensurate with closed-cycle 

cooling. 

. Exhibit I-34 below provides several examples and whether these hypothetical 

units will be defined as new or existing units. 

Exhibit I-34. Examples of new and existing units at existing electric generatorsgeneration facilities

Examples of new units at an existing facility Examples of existing units 

A unit that is constructed at a stand-alone location at 

an existing facility (either adjacent to existing units 

or on newly acquired or developed property) 

A unit where only the turbine is replaced, but not 

both the turbine and condenser 

A unit that is repowered, including the replacement 

of both the turbine and condenser (regardless of 

the change in generating capacity, the change in 

cooling water intake flow, or the use of an existing 

intake structure), except in the case of high 

energy efficiency units 

A unit where modifications are made to the turbine 

and/or condenser (e.g., optimization, repairs, 

upgrades to operational elements up to, but not 

including full replacement of the turbine or 

condenser, etc.) 

An existingA unit is retired before or after a new 

unitthat is constructed as a replacement 

(regardless of the change in generating capacity, 

the change in cooling water intake flow, or the use 

ofat a stand-alone location at an existing intake 

structure)

Increases in efficiency of the generating system that 

do not require replacement of the turbine or 

condenser, such as uprates at a nuclear 

generating unit
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An existing unit is retired and demolished, with a 

new unit constructed in the former unit’s location 

as a replacement (regardless of the change in 

generating capacity, the change in cooling water 

intake flow, or the use of an existing intake 

structure) 

A unit where a new boiler or fuel type is employed 

(e.g., a new heat recovery steam generator and 

combustion turbine is connected to an existing 

steam turbine and condenser)

An existing unit is retired and repowered in place, 

including the replacement of the turbine and 

condenser (regardless of the change in generating 

capacity, the change in cooling water intake flow, 

or the use of an existing intake structure), except 

in the case of high energy efficiency units 

A unit where upgrades or modifications are made to 

elements of the system unrelated to the turbine or 

condenser (e.g., boiler upgrade, modifications to 

control systems, addition or modification of air 

pollution controls, etc.) 

2. Manufacturers 

At manufacturing facilities that generate electricity onsite, the previous discussion 

of how to define new units at existing electric generatorsgenerating facilities generally

applies. Some manufacturers employ different industrial processes than an electric 

generator and therefore have different industrial equipment (including cooling systems). 

In particular, manufacturers may not use a steam condenser or steam turbine for their 

industrial processes, making the definition for “repowering” above inappropriate for 

manufacturing facilities. However, manufacturers domay have opportunities to reuse 

cooling water that power plants maydo not, and in site visits, EPA found many 

manufacturers have conducted energy and water audits resulting in significant reductions 

in water withdrawals. The final rule provides for manufacturers to receive credit for such 

reductions in fresh water withdrawals, 
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AIt is not as easy to identify a similar conceptual approach for defining new 

manufacturing units with a new or replaced cooling system is not as easily defined 

sinceat existing manufacturing facilities because waste heat can be generated from a 

variety of sources including exothermic processes, product heating and cooling, and the 

processing, handling, treating, or disposal of feed streams, waste streams, by-products, 

and recycled components. Sources may include direct cooling transferred across an inert 

material (e.g., heat exchanger, steam condenser), indirect cooling using a working fluid 

(e.g., chillers, refrigeration), or contact cooling where cooling water comes into direct 

contact with a product or process stream.15 Unlike electric generatorsgenerating units

where the majority of cooling water comes from a single process source (the steam 

condenser), manufacturing units may include many separate non-contact or contact 

cooling water sources dispersed throughout the production processes and the facility. 

Thus, a definition for manufacturing units with a new or replaced cooling system must 

take into consideration a broader category of cooling water sources. 

The conceptual equivalent of a steam turbine at a manufacturing unit would be the 

equipment that serves as the major source of waste heat associated with non-contact 

cooling water. The conceptual equivalent for the steam condenser would be the heat 

 

15Note that EPA did not include the contact cooling category as part of its analysis of possible closed-cycle 

coolingrecirculating system requirements but contact cooling water does nonetheless fall within the 

definition of cooling water at § 125.92. 
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exchange/transfer equipment that contributes heat to the non-contact cooling water. Thus, 

the final rule defines a new manufacturing unit as follows: 

Any newly built production units or replacement production units where 

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 are newly 

installed or replaced. 

While this definition may provide sufficient guidance regarding which 

manufacturing plant modifications are considered to be new units, the definition of “unit” 

itself may require some clarification. 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. But for some manufacturing facilities, it may be unclear what constitutes 

a “unit” since manufacturing processes can involve numerous vertically integrated 

processes or production steps that may involve intermediate products. For example, a unit 

could encompass an entire series of production steps (start to finish) or simply the 

individual steps. Also, there may be ancillary support equipment that serves various 

functions and it is not clear whether this will be considered a unit or part of a unit. To 

provide flexibility for these complexities, the final rule allows the Director broad 

discretion in making such determinations.16

 

16 Example definitions the Director might use could include: 
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For example, a petroleum refiner will typically include various processes such as 

distillation, cracking, hydrotreating, coking, reforming, and different types of various 

products. Various intermediate products from these processes may be directly transported 

(piped) from one process to another or stored and some may be sold. And because 

various intermediate and final process products may be blended into different products, 

differentiating units on a product or intermediate product basis may not provide clear 

distinctions. 

In summary, at a manufacturer, there are also two types of units that are defined 

as a new unit at an existing facility. First, a newly built, stand-alone unit (i.e., a unit 

where a new cooling system is built) that is constructed at an existing facility (and that 

does not meet the definition of a new facility) is defined as a new unit. Second, an 

existing unit that undergoes significant modifications (to a degree where the cooling 

system is replaced) is also a new unit at an existing facility including but not limited to 

the addition of a new production line. Under the second category, several types of 

modifications do not lead to considering the unit as a new unit, thereby defining the unit 

as an existing unit. In such cases, the existing unit is regulated under the existing unit 

 

 A new unit may include distinct production lines that are added to increase product output and 

operate parallel and independently of existing production equipment. 

 A new unit may include the replacement or rebuilding of distinct production lines or distinct 

processes where the majority of the waste heat producing equipment that serve as sources of noncontact cooling water and the majority of the heat exchanging equipment that contributes heat to 

the non-contact cooling water are replaced. This does not necessarily include replacement/upgrade 

of individual components or ancillary equipment alone. 
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provisions of this rule, and the unit is not subject to automatic requirements to reduce 

intake flow to a level commensurate with closed-cycle cooling. 

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 noncontact cooling water. Such modifications alone do not render the unit a new unit. A unit 

undergoing such modifications would continue to be considered an existing unit and 

would be regulated under the existing unit provisions of this rule. This definition 

therefore does not impose any disincentives for the replacement/upgrade of individual 

components or ancillary equipment alone. 

Exhibit I-45 below provides several examples andof whether these hypothetical 

units are defined as new or existing units. As noted above, the Director has broad 

discretion to assess the scope of any modifications at the manufacturing facility and to 

determine whether the most appropriate scale for defining the term “new construction 

comprises a stand-alone unit.”. For the purposes of today’s final rule, however, the 

Director should remain focused on does not need to address whether the stand-alone unit 

is for the cooling system and cooling water withdrawals, as manufacturing sites can be 

very complex, with intricate process flows, production lines, and other elements. But 
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thesame general industrial purposes, or whether the new unit is a replacement unit. The

key factors in assessing whether a unit will be defined as new lies with the cooling water 

use; these other complexities are ultimately not relevant to the determinationwhether the 

construction results in a stand-alone unit. 

Exhibit I-45. Examples of new and existing units at manufacturers 

Examples of new units at an existing facility Examples of existing units at an existing facility

A unit that is constructed at a stand-alone location at 

an existing facility (either adjacent to existing units 

or on newly acquired or developed property) 

A unit where only the waste heat generating process 

equipment or the cooling system equipment is 

replaced, but not both

A unit that is modified, including the replacement of 

the majority of the waste heat generating process 

equipment and the cooling system (e.g., heat 

exchanger, chiller) (regardless of the change in 

production capacity, the change in cooling water 

intake flow, or the use of an existing intake 

structure)A unit that is constructed adjacent to an 

existing unit for the same industrial activity (such 

as expanding the production output by building a 

second unit as a stand-alone unit next to the 

existing unit)

A unit where modifications are made to the waste 

heat generating process equipment or the cooling 

system (e.g., optimization, repairs, upgrades to 

operational elements up to, but not including full 

replacement))

An existing unit is retired before or after a new unit 

is constructed as a replacement (regardless of the 

change in production capacity, the change in 

cooling water intake flow, or the use of an existing 

intake structure) 

Replacement or upgrade of ancillary equipment (e.g., 

pumps, motors, HVAC, etc.)Increases in efficiency 

of the system that do not require replacement of 

the waste heat generating process equipment and 

the cooling system

An existing unit is retired and demolished, with a 

new unit constructed in the former unit’s location 

as a replacement (regardless of the change in 

production capacity, the change in cooling water 

intake flow, or the use of an existing intake 

structure) 

A unit where upgrades or modifications are made to 

elements of the system unrelated to the cooling 

system (e.g., production equipment upgrade or 

replacement, modifications to control systems, 

addition or modification of air pollution controls, 

etc.)

An existing unit is retired and rebuilt in place, 

including the replacement of the waste heat 

Replacement or upgrade of ancillary equipment (e.g., 

pumps, motors, HVAC, etc.)
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generating process equipment and the cooling 

system (regardless of the change in production 

capacity, the change in cooling water intake flow, 

or the use of an existing intake structure)

K. Amendments Related to the Phase I Rule 

EPA is making limited changes to the Phase I rule at 40 CFR Part 125 Subpart I. 

The changes fall into two categories. The first is deleting the provision in the Phase I rule 

that would allow a facility to demonstrate compliance with the Phase I BTA (best 

technology available) requirements in whole or in part through restoration measures. This 

change responds to the decision of the U.S. Court of Appeals for the Second Circuit, 

which remanded these provisions to EPA because it concluded that the statute did not 

authorize restoration measures to comply with CWA section 316(b) requirements. The 

second category of changes reflects technical corrections or errors that do not change the 

substance of the Phase I rule. EPA has not reopened any other aspects of the Phase I rule 

other than the provisions specifically noted here. 

1. Restoration Provisions Not Authorized 

The Phase I final rule established two compliance tracks. Track I requires 

facilities to restrict intake flow and velocity. Track II gives a facility the option of 

demonstrating to the Director that the control measures it employs will reduce the level of 

adverse environmental impact to a comparable level to what would be achieved by 

meeting the Track I requirements. As part of this demonstration, Track II originally 

allowed a facility to make use of restoration measures. The Comprehensive 
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Demonstration Study allowed a quantitative or qualitative demonstration that restoration 

measures would meet, in whole or in part, the performance levels of Track I. Similarly, 

the Verification Monitoring Plan could be tailored to verify that the restoration measures 

would maintain the fish and shellfish in the waterbody at a substantially similar level to 

that which would be achieved under Track I. See 66 FR 65280–65281, December 18, 

2001. 

Upon legal challenge, the Second Circuit Court concluded that EPA exceeded its 

authority by allowing new facilities to comply with CWA section 316(b) through 

restoration measures, and remanded that aspect of the rule to EPA. The Supreme Court 

did not grant the petitions for writs of certiorari concerning restoration provisions. 

Today’s final rule amends Phase I to remove those provisions in §§ 125.84(d) and 

125.89(b)(1)(ii) authorizing restoration measures in conformance with the Second’s 

Circuit’s decision. Today’s rule also specifically deletes permit application requirements 

contained in the Comprehensive Demonstration Study at § 125.86(c)(2)(ii); evaluation of 

proposed restoration measures at § 125.86(c)(2)(iv)(C); and verification monitoring 

requirements at § 125.86(c)(2)(iv)(D)(2) that are specific to restoration. EPA 

acknowledges these changes might reduce the alternatives available to some Phase I 

facilities. EPA notes, however, that the deletion of restoration measures does not 

otherwise alter the availability of Track II. In any event, EPA’s determination of BTA for 

Phase I did not presume reliance on the restoration provisions, and the deletion of 

restoration measures in no way alters the Agency’s BTA determination for Phase I 

facilities. 
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2. Corrections to Subpart I 

Today’s final rule changes the applicability of the technical requirements at § 

125.84 and permit application requirements at § 125.86 statement to match the 

applicability statement at § 125.81(a)(3). The applicability in all three instances should 

specify DIF or withdrawals “greater” than the specified value of 2 mgd. See Basis for the 

Final Regulation at 66 FR 65270, December 18, 2001. 

Today’s rule also corrects the source water bodywaterbody flow information 

submission requirements. Track I requirements at § 125.84(b)(3) apply to new facilities 

that withdraw equal to or greater than 10 mgd. Track I requirements at § 125.84(c)(2) 

apply to facilities that withdraw less than 10 mgd. The source water bodywaterbody flow 

information under § 125.86(b)(3) requires a facility to demonstrate it has met the flow 

requirements of both §§ 125.84(b)(3) “and” 125.84(c)(2). However, a facility cannot be 

subject to both §§ 125.84(b)(3) and 125.84(c)(2) at the same time. Accordingly, the word 

“and” should read as “or” in § 125.86(b)(3). 

In addition, today’s final rule corrects the permit application requirement for the 

Source Water Biological Characterization at § 122.21(r)(4). Accordingly, references to 

the Source Water Biological Characterization should read as (r)(4). However, the 

references to the Source Water Biological Characterization at § 125.86(b)(4)(iii), at § 

125.87(a), and at § 125.87(a)(2) incorrectly refer to § 122.21(r)(3) and are thus being 

corrected. 
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II. Legal Authority for and Background of the Final Regulation 

A. Legal Authority 

Today’s final rule is issued under the authority of CWAClean Water Act sections 

101, 301, 304, 308, 316, 401, 402, 501, and 510, 33 U.S.C. 1251, 1311, 1314, 1318, 

1326, 1341, 1342, 1361, and 1370. 

B. Purpose of the Regulation 

The purpose of today’s rule is to reduce impingement and entrainment of fish, 

shellfish and other aquatic organisms at cooling water intake structures. Today’s rule 

establishes national requirements for cooling water intake structures at existing facilities 

under section 316(b) of the CWA. That section provides that any standard established 

pursuant to CWA sections 301 or 306 and applicable to a point source must require that 

the location, design, construction, and capacity of cooling water intake structures reflect 

the BTA for minimizing adverse environmental impact. Today’s rule establishes 

requirements applicable to all existing power-generating facilities and existing 

manufacturing and industrial facilities that are point sources, that have a DIF of greater 

than 2 mgd from waters of the United States, and use at least 25 percent of the water they 

withdraw exclusively for cooling purposes on an actual intake flow basis. In addition, 

EPA is today also making minor changes to theits earlier rule establishing section 316(b) 

requirements for new facilities. Specifically, EPA is removing a provision that would 

have allowed a restoration-based alternative for complying with performance standards as 

well as the associated monitoring and other requirements for demonstrating compliance. 
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C. Background 

1. The Clean Water Act 

a. General 

The Federal Water Pollution Control Act, also known as the CWA (Clean Water 

Act),, 33 U.S.C. 1251 et seq., seeks to “restore and maintain the chemical, physical, and 

biological integrity of the nation’s waters.” 33 U.S.C. 1251(a). Among the goals of the 

Act is, wherever attainable, an interim goal of water quality which provides for the 

protection and propagation of fish, shellfish, and wildlife and provides for recreation in 

and on the water. 33 U.S.C. 1251(a)(2). 

In furtherance of these objectives, the CWA establishes a comprehensive 

regulatory program, key elements of which are (1) a prohibition on the discharge of 

pollutants from point sources to waters of the United States, except in compliance with 

the statute and (2) authority for EPA or authorized States or Tribes to issue NPDES 

permits that authorize and regulate the discharge of pollutants. 

CWA section 402 authorizes EPA (or an authorized State or Tribe) to issue an 

NPDES permit to any person discharging any pollutant or combination of pollutants from 

a point source into waters of the United States. Forty-sevensix States and one U.S. 

territory are authorized under section 402(b) to administer the NPDES permitting 

program. NPDES permits restrict the types and amounts of pollutants, including heat, that 

may be discharged from various industrial, commercial, and other sources of wastewater. 

These permits control the discharge of pollutants by requiring dischargers to meet 

technology-based and possibly water-quality-based effluent limitations. Under section 
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316(b), NPDES permits are required to contain conditions to implement the requirements 

of section 316(b). 

CWA section 510 provides that, except as provided in the CWA, nothing will 

preclude or deny the right of any State (or political subdivision thereof) to adopt or 

enforce any requirement respecting control or abatement of pollution; except that if a 

limitation, prohibition or standard of performance is in effect under the CWA, such State 

may not adopt any other limitation, prohibition, or standard of performance which is less 

stringent than the limitation, prohibition, or standard of performance under the Act. EPA 

interprets this to reserve for the States authority to implement requirements that are more 

stringent than the Federal requirements under state law. PUD No. 1 of Jefferson County v. 

Washington Dep't of Ecology, 511 U.S. 700, 705 (1994). New York and California have 

enacted State requirements that are at least as stringent as those of the final rule, and 

therefore, EPA has analyzed facilities in those States that are subject to those State 

requirements as already complying with the final rule.17 Those facilities still must comply 

with the administrative requirements of the final rule. 

CWA sections 301, 304, and 306 require that EPA develop technology-based 

effluent limitations guidelines and new source performance standards that are used as the 

basis for discharge requirements in wastewater discharge permits. EPA develops these 

effluent limitations guidelines and standards for categories of industrial dischargers on 

 

17 For example, California policy addressing 19 coastal power plants would not affect the compliance costs 

of inland facilities. 
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the basis of the pollutants of concern discharged by the industry in a relatively predictable 

manufacturing process, the degree of control that can be attained using various levels of 

pollution control technology appropriate for each industrial process or subcategory, 

consideration of various economic tests implemented under the authority of the CWA for 

each level of control, and other factors identified in CWA sections 304 and 306 (such as 

non-water quality environmental impacts including energy impacts). EPA has 

promulgated regulations setting effluent limitations guidelines and standards under CWA 

sections 301, 304, and 306 for 57 industry categories. See 40 CFR parts 405 through 471. 

EPA has established effluent limitations guidelines and standards that apply to the 

industry categories that are the largest users of cooling water (e.g., steam electric power 

generation, paper and allied products, petroleum refining, iron and steel manufacturing, 

and chemicals and allied products), as well as many other industrial categories that may 

include facilities subject to this final rule. 

b. Section 316(b) 

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. 

33 U.S.C. 1326(b). This provision is unique among CWA provisions because it 

addresses the adverse environmental impact caused specifically by the intake of cooling 

water, in contrast to other provisions of the Act that regulate the discharge of pollutants 

into waters of the United States. 
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The CWA does not further define the substantive standard specified in section 

316(b) – “best technology available for minimizing adverse environmental impact” 

(BTA). 33 U.S.C. 1326(b). The standard that cooling water intake structures must 

achieve under section 316(b) – BTA – is a different standard from those prescribed under 

sections 301 and 306 of the Act. Riverkeeper, Inc. v. v. EPA, 358 F.3d 174 (2d Cir. 2004). 

Moreover, unlike Sectionssections 304 and 306, Sectionsection 316(b) does not set forth 

the specific factors that the EPA must consider in determining BTA. BTA is “the only 

substantive statutory requirement explicitly applicable to the intake structure 

regulations.” Id. at 186. Unlike other provisions of the Act, section 316(b) standards are 

not subject to a “host” of other requirements or limitations. Ibid. There is no “elucidating 

language applicable to the BTA test.” Entergy Corp. v. Riverkeeper, Inc., 556 U.S. 208, 

221 (2009).18

Section 316(b) does, however, cross-reference Sectionssections 301 and 306 of 

the CWA by stating that any standards established pursuant to those sections also require 

that cooling water intake structures reflect BTA. Ibid. This cross reference, in the view of 

the Second Circuit, is an invitation, not a straitjacket. EPA “may” look to the referenced 

sections in discerning what factors Congress intended EPA to consider in determining 

BTA. 

 

18 Included in an appendix to the decision is a table comparing CWA statutory standards under 301, 306 

and 316(b), the table. In the column headed “Statutorily Mandated Factors,” for section 316(b), the table 

states “N/A.” 
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Because section 316(b) refers to sections 301 and 306 but provides a different 

standard ("best technology available for minimizing adverse environmental 

impact" instead of, for example, "best available demonstrated control 

technology") and does not explicitly provide that regulations pursuant to section 

316(b) are subject to the requirements of sections 301 and 306, we think it is 

permissible for the EPA to look to those sections for guidance but to decide that 

not every statutory directive contained therein is applicable to the Rule. 

The terse statutory description of BTA and the absence of any prescribed statutory 

factors for consideration in determining BTA suggest that Congress delegated EPA 

significant rulemaking discretion in this area.19

As notedAs noted, in contrast to effluent limitations guidelines and standards, the 

CWA does not describe the factors to be considered in establishing section 316(b) 

substantive performance requirements that reflect the “best technology available for 

minimizing adverse environmental impact” nor does it require that EPA develop uniform 

nationally applicable performance requirements through rule making. 

The U. S. Supreme Court has, however, recently provided guidance, in Entergy 

Corp. v. Riverkeeper, Inc., in interpreting section 316(b) and what factors EPA may 

consider in its standard-setting. That decision addressed the question of whether CWA 

section 316(b) authorizes EPA to compare costs and benefits of various technologies 

 

19The Second Circuit has noted the limited legislative history for section 316(b). “This paucity of legislative 

history, when measured against the volumes of drafts and speeches devoted to other aspects of the 1972 

amendments, and when combined with the brevity of the provision itself, counsels against imputing much 

specific intent to Congress beyond the section's words themselves. To the extent the provision is silent on 

issues to which other sections speak, we hesitate to draw the negative inference that the brevity of section 

316(b) reflects an intention to limit the EPA's authority rather than a desire to delegate significant 

rulemaking authority to the Agency.” Id. at 187. 
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when setting national performance standards for cooling water intake structures under 

CWA section 316(b). In overturning EPA’s earlier rule to establish section 316(b) 

requirements for existing facilities, the Second Circuit held that balancing costs and 

benefits was an impermissible factor for standard setting under section 316(b). The 

Supreme Court reversed and remanded the Second Circuit ruling in a 6-3 opinion 

authored by Justice Scalia. The Court held that it is permissible for EPA to consider a 

cost-benefit analysis in setting national performance standards for cooling water intake 

structures under section 316(b). The Court held that EPA has the discretion to consider 

costs and benefits under section 316(b) but is not required to do so. 556 U.S. 208, 222-23.

The Court’s discussion of the language of section 316(b)—section 316(b) is 

“unencumbered by specified statutory factors”—and its critique of the Second Circuit’s 

decision affirms EPA’s broad discretion to consider a number of factors in standard 

setting under section 316(b). While the Supreme Court’s decision is limited to whether or 

not EPA may properly consider one factor (cost/benefit analysis) under section 316(b), 

the language also indicates that EPA has wide discretion in considering other factors that 

it deems relevant to 316(b) standard setting. 556 U.S. 208, 222 (2009) (“It is eminently 

reasonable to conclude that § 1326b’s silence is meant to convey nothing more than a 

refusal to tie the agency’s hands as to whether cost-benefit analysis should be used, and if 

so to what degree.” 556 U.S. 208, 222 (2009)..”).

Regarding the other factors EPA may, but is not mandated to, consider, as noted 

above, section 316(b) cross references CWA sections 301 and 306 by requiring that any 

standards established pursuant to those sections also must require that the location, 
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design, construction and capacity of intake structures reflect BTA. Following the 

decisions of the Second Circuit in reviewing both the Phase I and Phase II rules, EPA has 

interpreted the cross reference as authorizing consideration of the same factors 

considered under those provisions to help guide section 316(b) rulemaking without 

determining that each of those factors is applicable to this rule. Thus, for example, 

section 306 directs EPA to establish performance standards for new sources based on the 

BADT (best available demonstrated control technology). 33 U.S.C. 1316(a)(1). In 

establishing BADT, EPA “shall take into consideration the cost of achieving such 

effluent reduction, and any non-water quality environmental impact and energy 

requirements.” 33 U.S.C. 1316(b)(2)(B). 

Similarly, CWA section 301 requires EPA to establish standards known as 

effluent limitations guidelines for existing point source discharges in two phases. In the 

first phase, applicable to all pollutants, EPA must establish effluent limitations based on 

the BPT (best practicable control technology currently available). 33 U.S.C. 

1311(b)(1)(A). In establishing BPT, the CWA directs EPA to consider the total cost of 

application of technology in relation to the effluent reduction benefits to be achieved 

from such application, and to also take into account the age of the equipment and 

facilities involved, the process employed, the engineering aspects of the application of 

various types of control techniques, process changes, non-water quality environmental 

impacts (including energy requirements), and such other factors as EPA deems 

appropriate. 33 U.S.C. 1314(b)(1)(b). 
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EPA must also establish effluent limitations for conventional pollutants based on 

the BCT (best conventional pollution control technology), and for toxic pollutants based 

on the BAT (best available technology economically achievable). 33 U.S.C. 

1311(b)(2)(A), (E). 

In determining BCT, EPA must consider, among other factors, 

the relationship between the costs of attaining a reduction in effluents and 

the effluent reduction benefits derived, and the comparison of the cost and 

level of reduction of such pollutants from the discharge from publicly 

owned treatment works to the cost and level of reduction of such 

pollutants from a class or category of industry source.... and the age of 

equipment and facilities involved, the process employed, the engineering 

aspects .... of various types of control techniques, process changes, the 

cost of achieving such effluent reduction, non-water quality environmental 

impacts (including energy requirements), and such other factors as [EPA] 

deems appropriate. 33 U.S.C. 1314(b)(4)(B) 

In determining BAT, the CWA directs EPA to consider “the age of equipment and 

facilities involved, the process employed, the engineering aspects .... of various types of 

control techniques, process changes, the cost of achieving such effluent reduction, nonwater quality environmental impacts (including energy requirements), and such other 

factors as [EPA] deems appropriate.” 33 U.S.C. 1314(b)(2)(B) 

While Section, in establishing standards known as effluent limitations guidelines, 

to consider specified factors. For a complete discussion of factors considered in 

establishing section 301 effluent limits, see 76 FR 22178-22179, April 20, 2011. But, 

EPA in establishing section 316(b) standards is not constrained in what factors it 

considers or bound by any statutorily prescribed tests as is the case with sections 301 and 

306. Consequently, while section 316(b) expressly refers to section 301 and 306, and, 
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while it shares some of the same words used in sections 301(b) and 306, its language is 

different.20 These differences in the statutory descriptions, coupled with the brevity of 

section 316(b) itself, prompt EPA to look, in part, toexamine the factors described in 

section 301, 306 and, ultimately, section 304 aswhere relevant factors in 

determiningEPA’s determination of the “best technology available to minimize adverse 

environmental impact” of cooling water for intake structures for existing facilities.21

By the same token, however, asAs noted above, there are significant differences 

between section 316(b) and sections 301, 304 and 306. See Riverkeeper, Inc. v. United 

States Environmental Protection Agency (2nd Cir. Feb. 3, 2004) (“not every statutory 

directive contained [in sections 301 and 306] is applicable” to a section 316(b) 

rulemaking). Moreover, as the Supreme Court recognized, while the provisions 

governing the discharge of toxic pollutants must require the elimination of discharges if 

technically and economically achievable, section 316(b) has the less ambitious goal of 

“minimizing adverse environmental impact.” 556 U.S. at 219. In contrast to the effluent 

limitations provisions, the object of the best technology available is explicitly articulated 

 

20Compare “best technology available for minimizing adverse environmental impacts” with “best 

practicable control technology currently available”( 301(b)(1)A)), “best conventional pollutant control 

technology (301(b)(2)(E)) “best available technology economically achievable” (301(b)(2)(A)), and best 

available demonstrated control technology, (306(b)(1)(B)). Section 316(b), section 301(b)(1)(A)—the BPT 

provision— section 301(b)(2)(E) – the BCT provision -- section 301(b)(1)(B)—the BAT provision— and 

section 306(b)(2)(E). All include the terms “best,” “technology,” and “available,” but none also include the 

modifying phrase “for minimizing adverse environmental impacts,” found in section 316(b). See 33 U.S.C. 

1311(b)(1)(A) and (2)(A). 

21 As noted here, the term BTA means “best technology available for minimizing adverse environmental 

impact.” In the interests of brevity, the acronym will frequently be used in the preamble to reflect the entire 

definition. 
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by reference to the receiving water: to minimize adverse environmental impact in the 

waters from which cooling water is withdrawn. This difference is reflected in EPA’s past 

practices in implementing sections 301, 304, andas contrasted with 316(b). For example,

EPA has established BAT effluent limitations guidelines and new source performance 

standards on the basis of the efficacy of one or more technologies to reduce pollutants in 

wastewater in relation to their costs without necessarily considering the impact on the 

receiving waters. This contrasts to 316(b) requirements which historically have been 

developed on a site-specific basis, where EPA has considered the costs of technologies in 

relation to the benefits of minimizing adverse environmental impact in establishing 

316(b) limitsrequirements. In Re Public Service Co. of New Hampshire, 10 ERC 1257 

(June 17, 1977); In Re Public Service Co. of New Hampshire, 1 EBAD 455 (Aug. 4, 

1978); Seacoast Anti-Pollution League v. Costle, 597 F. 2d 306 (1st Cir. 1979). EPA 

concluded that, because both section 301 and 306 are expressly cross-referenced in 

section 316(b), EPA could reasonably interpret section 316(b) as authorizing 

consideration, where appropriate, of the same factors, including costs, as in those sections 

even if not in the same way. Over the years, EPA has interpreted best technology 

available in section 316(b) to mean the best technology available at an economically 

practicable cost. This approach squared with the limited legislative history of section 

316(b) which suggested the BTA was to be based on technology whose costs were 

economically practicable. In debate on section 316(b), one legislator explained that “[t]he 

reference here to ‘best technology available’ is intended to be interpreted to mean the best 

technology available commercially at an economically practicable cost.” 118 Cong. Rec. 
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33,762 (1972) (statement of Rep. Clausen) (emphasis added).. EPA stresses that it may 

therefore consider some of the same factors, even if it is not legally required to consider 

them in the same way. 

2. The Consent Decree 

2. Early Litigation History 

On January 19, 1993, a group of individuals and environmental organizations22

filed, under CWA section 505(a)(2), 33 U.S.C. 1365(a)(2), a complaint in Cronin, et. al. 

v. Reilly, 93 Civ. 314 (LTS)(S.D.N.Y.). The plaintiffs alleged that EPA had failed to 

perform a nondiscretionary duty to issue regulations implementing CWA section 316(b), 

33 U.S.C. 1326(b). In 1995, EPA and the plaintiffs executed a consent decree in the case. 

As amended, it provided for EPA to implement CWA section 316(b) by prescribed dates 

in the three separate rule-making proceedings. Phase I concerned cooling water intake 

structures at new facilities, Phase II existing power plants using large volumes of cooling 

water and Phase III for existing smaller-flow power plants and factories in at least four 

industrial sectors (pulp and paper making, petroleum and coal products manufacturing, 

chemical and allied manufacturing, and primary metal manufacturing). EPA promulgated 

 

22 The plaintiffs are the following: Riverkeeper, Inc.; Alex Matthiessen, a/k/a The Hudson Riverkeeper; 

Maya K. Van Rossum, a/k/a The Delaware Riverkeeper; Terrance E. Backer, a/k/a The Soundkeeper; John 

Torgan, a/k/a The Narragansett BayKeeper; Joseph E. Payne, a/k/a The Casco BayKeeper; Leo O’Brien, 

a/k/a the San Francisco BayKeeper; Sue Joerger, a/k/a The Puget Soundkeeper; Steven E. Fleischli, a/k/a 

The Santa Monica BayKeeper; Andrew Willner, a/k/a The New York/New Jersey Baykeeper; The Long 

Island Soundkeeper Fund, Inc.; The New York Coastal Fishermen’s Association, Inc.; and The American 

Littoral Society, Inc. 
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the Phase I rule in December, 2001, the Phase II rule in July, 2004 and the Phase III rule 

in June, 2006. 

On November 17, 2006, some of the same environmental organizations in the 

Cronin case filed a second complaint, amended on January 19, 2007, in Riverkeeper, et 

al. v. EPA, 06 Civ. 12987 (S.D.N.Y.) asserting that EPA’s Phase III rule failed to 

discharge EPA’s duty under CWA section 316(b). 

On August 14, 2008, EPA filed a motion to terminate the Cronin proceeding 

because it had discharged its obligations (to take final action) under the decree with 

respect to the 2004 Phase II and 2006 Phase III rulemakings. Subsequently, EPA entered 

into a settlement with the plaintiffs in both lawsuits. Under the settlement agreement, 

EPA agreed to sign a notice of a proposed rulemaking implementing CWA section 

316(b) at existing facilities no later than March 14, 2011, and to sign a notice taking final 

action on the proposed rule no later than July 27, 2012. Plaintiffs agreed to seek dismissal 

of both their suits, subject to a request to reopen the Cronin proceeding if EPA failed to 

meet the agreed deadlines. The district courts have now entered orders of dismissal. On 

March 11, 2011, the parties agreed to an amendment to the settlement agreement to 

extend the date for proposal to March 28, 2011. On July 17, 2012, the parties agreed to an 

amendment to the settlement agreement to extend the date for the final rule to June 27, 

2013. On June 21, 2013, the parties agreed to extend the date to November 4, 2013, to 

accommodate completion of formal consultation under the Endangered Species Act. In 

part due to the government shutdown, on November 12, 2013, the parties agreed to 

extend the date to January 14, 2014. On February 10, 2014, to continue progress on the 
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Endangered Species Act (ESA) consultation process, the parties agreed to extend the date 

to April 17, 2014. Finally, on April 23 2014, in a conference with the court EPA 

informed the judge that the EPA and the Services would complete the ESA consultation, 

so that the EPA would sign the rule by May 16, 2014. The court entered an order 

provisionally reinstating the case if EPA failed to inform the court by May 19, 2014 that 

it had taken the contemplated action. On May 19, 2014, the Administrator signed this 

notice for publication in the Federal Register.

3. Prior EPA Actions to Address Cooling Water Intake Structures 

a. 1976 Rulemaking 

In April 1976, EPA promulgated regulations under section 316(b) that addressed 

cooling water intake structures. 41 FR 17387 (, April 26, 1976).. The rule added a new § 

401.14 to 40 CFR Chapter I that reiterated the requirements of CWA section 316(b). It 

also added a new part 402, which included three sections: (1) § 402.10 (Applicability), 

(2) § 402.11 (Specialized definitions), and (3) § 402.12 (Best technology available for 

cooling water intake structures). Section 402.10 stated that the provisions of part 402 

applied to “cooling water intake structures for point sources for which effluent limitations 

are established pursuant to section 301 or standards of performance are established 

pursuant to section 306 of the Act.” Section 402.11 defined the terms cooling water 

intake structure, location, design, construction, capacity, and Development Document. 

Section 402.12 included the following language: 

“The information contained in the Development Document shall be considered in 

determining whether the location, design, construction, and capacity of a cooling water 
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intake structure of a point source subject to standards established under section 301 or 

306 reflect the best technology available for minimizing adverse environmental impact.” 

In 1977, 58 electric utility companies challenged those regulations, arguing that 

EPA had failed to comply with the requirements of the Administrative Procedure Act in 

promulgating the rule. Specifically, the utilities argued that EPA had violated the 

Administrative Procedure Act in promulgating regulations mandating consideration of 

the information in the Development Document in establishing 316(b) conditions in 

individual NPDES permits because EPA had neither published the Development 

Document in the Federal Register nor properly incorporated the document into the rule 

by reference. The U.S. Court of Appeals for the Fourth Circuit agreed. The court 

determined that the information in the Development Document was part of the substance 

of a regulation imposing specific obligations in mandatory terms. As such, the 

information must either be published in the Federal Register in its entirety or to be 

reasonably available and properly incorporated by reference under Federal Register 

requirements. The court explained it did not object to site-specific implementation of the 

section 316(b) requirements (“[w]hile we emphasize we do not fault EPA for its point 

source by point source application”), it did require EPA to “devise a less uncertain 

method of advising those affected of the conditions by which they are to be bound.” 

Appalachian Power Co. v. Train, 566 F.2d 451, 457 (4th Cir. 1977). Without reaching 

the merits of the regulations themselves, the court remanded the rule. EPA later withdrew 

part 402. (See 44 FR 32956, June 7, 1979.) Section 402.10, however, now codified at § 

401.14, remains in effect. 
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Following the Fourth Circuit remand of EPA’s section 316(b) regulations in 1977, 

NPDES permit authorities have made decisions implementing CWA section 316(b) and § 

401.14 without the direction of a national rule. EPA published draft guidance addressing 

section 316(b) implementation in 1977. See Draft Guidance for Evaluating the Adverse 

Impact of Cooling Water Intake Structures on the Aquatic Environment: Section 316(b) 

Pub. L. 92–500 (U.S. EPA 1977). That draft guidance describes the studies recommended 

for evaluating the impact of cooling water intake structures on the aquatic environment 

and recommends a basis for determining the BTA for minimizing adverse environmental 

impact. The 1977 section 316(b) draft guidance states, “[t]he environmental-intake 

interactions in question are highly site-specific and the decision as to best technology 

available for intake design, location, construction, and capacity must be made on a caseby-case basis” (Section 316(b) Draft Guidance, U.S. EPA 1977, p. 4). This site-specific 

approach was also consistent with the approach described in the 1976 Development 

Document referenced in the remanded regulation. (See DCN 1-1056-TC from the Phase I 

docket.) The 1977 section 316(b) draft guidance suggested a general process for 

developing information needed to support section 316(b) decisions and presenting that 

information to the Director. The process involved developing a site-specific study of the 

environmental effects associated with each facility that uses one or more cooling water 

intake structures, and consideringconsideration of that study by the Director in 

determining whether the facility must make any changes for minimizing adverse 

environmental impact. Under this framework, the Director determined whether 
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appropriate studies have been performed, whether a given facility has minimized adverse 

environmental impact, and what, if any, technologies may be required. 

b. Phase I – New Facility Rule 

i. Rulemaking 

On November 9, 2001, EPA took final action on regulations governing cooling 

water intake structures at new facilities. See 66 FR 65255, December 18, 2001. On 

December 26, 2002, EPA made minor changes to the Phase I regulations. 67 FR 78947. 

The final Phase I new facility rule (40 CFR 125, Subpart I) establishes requirements 

applicable to the location, design, construction, and capacity of cooling water intake 

structures at new facilities that have a design capacity to withdraw greater than 2 mgd 

and use at least 25 percent of the water they withdraw solely for cooling purposes on an 

actual intake flow basis. 

In the new facility rule, EPA adopted a two-track approach. Under Track I, for 

facilities that withdraw equal to or greater than 10 mgd, must were required to meet three 

requirements. First, the intake flow of the cooling water intake structure is restricted, at a 

minimum, to a level commensurate with that which could be attained by use of a closedcycle, recirculating cooling system. Second, the design through-screen intake velocity is 

restricted to 0.5 fps (foot per second). Third, the total quantity of intake is restricted to a 

proportion of the mean annual flow of a freshwater river or stream, or to a level necessary 

to maintain the natural thermal stratification or turnover patterns (where present) of a lake 

or reservoir except in cases where the disruption is beneficial, or to a percentage of the 

tidal excursions of a tidal river or estuary. Further, if there are, for example, endangered 
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or threatened species stressed by a facility’s intake structure, a facility that would 

otherwise meet the applicable performance requirements may have to select and 

implement additional design and construction or operational measures to address 

impingement mortality and entrainment if these measures are inadequate to protect the 

species. Facilities with greater than 2 mgd but less than 10 mgd flows are not required to 

reduce intake flow to a level commensurate with a closed-cycle, recirculating cooling 

system, but they must still meet specific operational criteria. 

Under Track II, a facility hashad the opportunity to demonstrate to the NPDES 

permitting authority (Director) that the technologies it employs will reduce the level of 

adverse environmental impact to a comparable level to what would be achieved by 

meeting the Track I requirements for restricting intake flow and velocity. In making this 

demonstration, the regulations allow a facility to rely on a combination of measures in 

addition to technology controls for reducing impingement and entrainment to achieve 

results equivalent to the Track I intake flow and velocity requirements. Among these 

measures, the rule would have allowed restoration of the affected water bodywaterbody

through efforts such as restocking fish and improving the surrounding habitat to offset the 

adverse effects that would otherwise be caused by operating the intake structures. The 

Second Circuit, in reviewing the new facility rule, determined that section 316(b) did not 

authorize the use of restoration measures in complying with the EPA performance 

standard. (Note that EPA is removing the provision related to restoration measures from 

the CFR in this rulemaking but has included the above description of the Phase I rule for 

completeness.) For more information, see sectionSection I above. 
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In addition, under the Phase I rule, the Director may establish less stringent 

alternative requirements for a facility if compliance with the Phase I 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. 

EPA specifically excluded new offshore oil and gas extraction facilities from the 

Phase I new facility rule but committed to consider establishing requirements for such 

facilities in the Phase III rulemaking. 66 FR 65338, December 18, 2001. 

ii. Subsequent Litigation 

Various environmental and industry groups challenged the Phase I rule. In 

February 2004, the Second Circuit sustained the entire rule except for the restoration 

provision, ruling that restoration was not a technology as provided for in section 316(b). 

With respect to the other provisions of the rule, the court concluded the Phase I rule was 

based on a reasonable interpretation of the applicable statute and sufficiently supported 

by the record. Restoration provisions of the rule were remanded to EPA for further 

rulemaking consistent with the court’s decision. Riverkeeper, Inc. v. EPA, 358 F.3d 174, 

191 (2nd Cir., 2004). Today’s rule removes the restoration provisions from the Phase I 

rule. For more details, see Chapter I of this preamble. 

c. Phase II – Large Flow Existing Power Plants 

i. Rulemaking 

On February 16, 2004, EPA took final action on regulations governing cooling 

water intake structures at certain existing power-producing facilities. 69 FR 41576, July 
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9, 2004. The final 2004 Phase II rule applied to existing facilities that are point sources; 

that, as their primary activity, both generate and transmit electric power or generate 

electric power for sale or transmission; that use or propose to use a cooling water intake 

structure with a total DIF of 50 mgd or more to withdraw water from waters of the United 

States; and that use at least 25 percent of the withdrawn water exclusively for cooling 

purposes on an actual intake flow basis. In addition, power producers fitting the 

description above were also subject to the final 2004 Phase II rule even if they obtain 

their cooling water from one or more independent suppliers of cooling water. Such 

facilities were subject to the rule if their supplier withdraws water from waters of the 

United States even if the supplier was not itself a 2004 Phase II existing facility. EPA 

included this provision to prevent circumvention of the 2004 Phase II rule requirements 

by a facility purchasing cooling water from entities not otherwise subject to section 

316(b). 

The final 2004 Phase II rule and preamble also clarified the definition of an 

existing power-producing facility. The 2004 Phase II rule defined an existing facility as 

“any facility that commenced construction as described in § 122.29(b)(4) on or before 

January 17, 2002; and any modification of, or addition of a unit at such a facility that 

does not meet the definition of a new facility at § 125.83.” Because the definition of the 

term existing facility was based in part on the Phase I definition of the term new facility, 

the preamble to the final 2004 Phase II rule also clarified and provided some examples of 

how the definition of existing facility might apply to certain changes at power-producing 

facilities. 
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Under the 2004 Phase II rule, EPA established BTA performance standards for 

the reduction of impingement mortality and, under certain circumstances, entrainment 

(see 69 FR 41590-41593, July 9, 2004). The performance standards consisted of ranges 

of reductions in impingement mortality and, if applicable, entrainment (e.g., reduce 

impingement mortality by 80 to 95 percent and/or entrainment by 60 to 90 percent) 

relative to a calculation baseline that reflected the level of impingement mortality and 

entrainment that would occur absent specific controls. These performance standards were 

not based on a single technology but, rather, on consideration of a suite of technologies 

that EPA determined were commercially available and economically achievable for the 

industries affected as a whole (69 FR 41598-41610, July 9, 2004). EPA based the 

impingement mortality and entrainment performance standards on a suite of technologies 

because it found no single technology to be effective at all affected facilities. For 

impingement standards, these technologies included the following: (1) fine- and widemesh wedgewire screens, (2) barrier nets, (3) modified screens and fish return systems, 

(4) fish diversion systems, and (5) fine-mesh traveling screens and fish return systems. 

With regard to entrainment reduction, these technologies include the following: (1) 

aquatic filter barrier systems, (2) fine-mesh wedgewire screens, and (3) fine-mesh 

traveling screens with fish return systems. Because EPA based the performance standards 

on a combination of technologies and because of the uncertainty inherent in predicting 

the efficacy of one or more of these technologies as applied to different facilities, EPA 

promulgated these standards as ranges. Furthermore, because the site-specific 

performance was based on a comparison to a once-through system without any specific 
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controls on the shoreline near the source water bodywaterbody (i.e., calculation baseline, 

for more details see sectionSection III.B.1 of the preamble to the proposed rule, 76 FR 

22185, April 20, 2011), the rule also allowed facilities to receive credit toward meeting 

the performance standards for impingement and entrainment reduction associated with 

alternative locations of their intakes (e.g., deep water where fish and shellfish were less 

abundant). 

The types of performance standard applicable to a facility (i.e., reductions in 

impingement mortality only or both impingement mortality and entrainment) were based 

on several factors, including the facility’s location (i.e., source water bodywaterbody), 

rate of use (capacity utilization rate), and the proportion of the water bodywaterbody

withdrawn. 

The 2004 Phase II rule identified five compliance alternatives to meet the 

performance standards. A facility could demonstrate to the Director one of the following: 

(1) that it has already reduced its flow commensurate with a closed-cycle recirculating 

system (to meet both impingement mortality and entrainment), or that it has already 

reduced its maximum through-screen velocity to 0.5 fps or less (to meet the impingement 

performance standard only); (2) that its cooling water intake structure configuration 

meets the applicable performance standards; (3) that it has selected design and 

construction technologies, operational measures, and/or restoration measures that, in 

combination with any existing design and construction technologies, operational 

measures, and/or restoration measures, meet the applicable performance standards; (4) 

that it meets the applicability criteria and has installed and is properly operating and 
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maintaining a rule-specified and/or approved State-specified design and construction 

technology (i.e., submerged cylindrical wedgewire screens) in accordance with § 

125.99(a) or an alternative technology that meets the appropriate performance standards 

and is approved by the Director in accordance with § 125.99(b); or (5) that its costs of 

compliance would be significantly greater than either the costs considered by the 

Administrator for a like facility to meet the applicable performance standards, or the 

benefits of meeting the applicable performance standards at the facility. Under the costcost comparison alternative, a Director could determine that the cost of compliance for a 

facility would be significantly greater than the costs considered by EPA in establishing 

the applicable impingement mortality and entrainment performance standards. Similarly, 

under the cost-benefit comparison alternative, a Director could determine that the cost of 

compliance for a facility would be significantly greater than the benefits of complying 

with the applicable performance standards. If either of these determinations were made, 

the Director would have to make a site-specific determination of BTA for minimizing 

adverse environmental impact that came as close as possiblepracticable to meeting the 

applicable performance standards at a cost that did not significantly exceed either the 

costs EPA considered in establishing these standards or the site-specific benefits of 

meeting these standards. 

The final 2004 Phase II rule also provided that a facility that chooses specified 

compliance alternatives might request that compliance with the requirements of the rule 

be determined on the basis of implementing a Technology Installation and Operation Plan 

(TIOP) that would indicate how the facility would install and ensure the efficacy, to the 
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extent practicable, of design and construction technologies, and/or operational measures, 

and/or a Restoration Plan. The rule also established requirements for developing and 

submitting a TIOP (§ 125.95(b)(4)(ii)) and provisions that specified how compliance 

could be determined on the basis of implementing a TIOP (§ 125.94(d)). Under these 

provisions, a TIOP could be requested in the first permit term, and continued use of a 

TIOP could be requested where a facility was in compliance with such plan and/or its 

Restoration Plan. 

ii. Subsequent Litigation 

Industry, environmental stakeholders, and some States23 challenged many aspects 

of the 2004 Phase II regulations. On January 25, 2007, the Second Circuit (Riverkeeper, 

Inc. v. EPA, 475 F.3d 83, (2d Cir., 2007)) upheld several provisions of the 2004 Phase II 

rule and remanded others to EPA for further rulemaking. 

As noted above, for the 2004 Phase II rule EPA rejecteddid not select closedcycle cooling as BTA. Instead, EPA selected a suite of technologies to reflect BTA, 

including, for example, screens, aquatic filter barriers, and barrier nets. According to the 

chosen technologies, EPA established national performance standards for reducing 

impingement mortality and entrainment of fish and fish organisms but did not require the 

use of any specific technology. Among the aspects of the rule the Second Circuit 

 

23Rhode Island, Connecticut, Delaware, Massachusetts, New Jersey, and New York. 
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remanded for further clarification was EPA’s decision to reject closed-cycle cooling as 

BTA and EPA’s determination of performance ranges as BTA. In addition, the Second 

Circuit found that, consistent with its Phase I decision, restoration was not authorized 

under the CWA as a technology for BTA and that EPA’s cost-benefit site-specific 

compliance alternative was not in accord with the CWA. There are also several issues for 

which the court requested additional clarification and some instances where the court 

determined that EPA had failed to provide adequate notice and opportunity to comment 

on certain provisions of the rule. 

iii. Suspension 

As a result of the decision in Riverkeeper, Inc. v. EPA, 475 F.3d 83, (2d Cir., 

2007), EPA, on July 9, 2007 (72 FR 37107) suspended the requirements for cooling 

water intake structures at 2004 Phase II existing facilities, pending further rulemaking. 

Specifically, EPA suspended the provisions in § 122.21(r)(1)(ii) and (r)(5), and part 125 

Subpart J, with the exception of § 125.90(b). EPA explained that suspending the 2004 

Phase II requirements was an appropriate response to the Second Circuit’s decision and 

that such action would allow it to consider how to respond to the remand. In addition, 

suspending the 2004 Phase II rule was responsive to the concerns of the regulated 

community and permitting agencies, both of whom sought guidance regarding how to 

proceed in light of the approaching deadline for compliance with the remanded rule. 

EPA’s suspension clarified that pending further rulemaking, permit requirements for 

cooling water intake structures at 2004 Phase II facilities should be established on a caseby-case, BPJ basis (see § 125.90(b)). 
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iv. Supreme Court Decision 

Following the decision in the Second Circuit, several industry group litigants 

petitioned the U.S. Supreme Court to hear an appeal regarding several issues in the case. 

Entergy Corp. v. Riverkeeper, Inc. et al., S. Ct. No. 07-588, et al. On April 14, 2008, the 

Supreme Court granted the petitions for writs of certiorari submitted by these 2004 Phase 

II litigants, but it limited its review to the issue of whether section 316(b) authorizes EPA 

to compare costs with benefits in determining BTA for cooling water intake structures. 

The Supreme Court held oral arguments in this case on December 2, 2008, and issued a 

decision on April 1, 2009. As explained above, the Supreme Court held that it is 

permissible for EPA to rely on cost-benefit analysis in decision making. The court 

indicated that the phrase “best technology available for minimizing adverse 

environmental impact” does not unambiguously preclude use of cost-benefit analysis in 

decision making. 566 U.S. at 223(2009). The ruling supports EPA’s discretion to 

consider costs and benefits, but it imposes no obligation on the Agency to do so. 

d. Phase III – Existing Power Plants Below 50 mgd, Existing Manufacturing 

Facilities, and New Offshore Oil and Gas Facilities 

i. Rulemaking

On June 16, 2006, EPA published a final Phase III rule that established 

categorical regulations for new offshore oil and gas extraction facilities that have a DIF 

threshold of greater than 2 mgd and that withdraw at least 25 percent of the water 

exclusively for cooling purposes on an actual intake flow basis. The rule establishes 

requirements that address intake velocity, proportionate flow for sensitive locations, 
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design and construction technologies or operational measures, monitoring and 

recordkeeping, based on if a facility employs a sea chest or not, and is fixed or not. Like 

the Phase I rule, this rule includes a Track II. In the Phase III rule, EPA declined to 

establish national standards for Phase III existing facilities. Instead it concluded that 

CWA section 316(b) requirements for electric generators with a DIF of less than 50 mgd 

and all existing manufacturing facilities would continue to be established on a case-bycase basis under the NPDES permit program using BPJ. (71 FR 35006, June 16, 2006). 

ii. Subsequent Litigation 

Following promulgation of the rule, a number of parties filed petitions for review 

that were subsequently consolidated for hearing in the U.S. Court of Appeals for the Fifth 

Circuit. In 2009, EPA petitioned the Fifth Circuit to remand to the Agency those parts of 

the rule that applied to existing facilities. Specifically, EPA requested remand of those 

provisions in the Phase III rule that establish 316(b) requirements at electric generators 

with a DIF of less than 50 mgd, and the provision establishing requirements for existing 

manufacturing facilities on a case-by-case basis using BPJ. This request did not affect the 

Phase III rule requirements that establish categorical regulations for new offshore oil and 

gas extraction facilities that have a DIF threshold of greater than 2 mgd and that 

withdraw at least 25 percent of the water exclusively for cooling purposes on an actual 

intake flow basis. 

On July 23, 2010, the U.S. Court of Appeals for the Fifth Circuit issued a decision 

affirming the parts of Phase III rule relating to new offshore oil and gas facilities. The 

court granted EPA’s motion to remand the rule with respect to existing facilities. In 
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sustaining the requirements for new offshore oil and gas facilities, the Fifth Circuit 

upheld EPA’s decision not to use cost benefit balancing in determining the requirements 

for these new facilities. 

III. Environmental Effects Associated with Cooling Water Intake Structures 

A. Introduction 

Multiple types of adverse environmental effects may be associated with CWIS 

operations at regulated facilities. Many facilities employ once-through cooling water 

systems that impinge fishes and other aquatic organisms on intake screens. Impinged 

organisms may be killed, injured, or weakened. In addition, early life stage fish or 

planktonic organisms can be entrained by the CWIS and subjected to high velocity and 

pressure, increased temperature, and chemical anti-biofouling agents in the system. These 

factors are highly lethal in most cases, as early life stages of larvae are highly sensitive 

and very unlikely to survive entrainment. Even if an organism is entrained as an egg and 

survives, its chances of surviving beyond the larvae stage are dramatically lower than 

eggs that were never entrained. Thus, unless measures to protect larvae are in place, egg 

survival does not indicate that adverse environmental impacts have been avoided. 

Consistent with its treatment of entrainment in past 316(b) rules, EPA assumes for the 

purposes of a national rule that 100 percent of entrained organisms suffer mortality. 

The effects of CWIS on aquatic habitats and biota in the waterbody do not occur 

in isolation from other ongoing physical, chemical, and biological stressors. 

Anthropogenic stressors may include: degraded water and sediment quality, low 
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dissolved oxygen (DO) levels, eutrophication, fishing, channel or shoreline (habitat) 

modification (intake structure and other flood or storm controls), hydrologic regime 

changes and invasive species. For example, many aquatic organisms subject to IM&E 

(impingement mortality and entrainment) reside in impaired (i.e., CWA 303(d) listed) 

waterbodies. The effects of anthropogenic stressors on biota may contribute to or 

compound the impact of IM&E, depending on the influence of location-specific factors. 

In addition to stressors acting on biota near a single CWIS, multiple CWISs and facilities 

located in close proximity on the same waterbody may have additive or cumulative 

effects on aquatic communities. And, although it is difficult to measure, the 

compensatory ability of an aquatic population, which is the capacity for a species to 

increase survival, growth, or reproduction rates in response to decreased population, is 

likely compromised by IM&E and the cumulative impact of other stressors in the 

environment over extended periods of time.

B. Major Anthropogenic Stressors in Aquatic Ecosystems 

All ecosystems and their biota are subject to natural variability in environmental 

conditions (e.g., seasonal cycles, foliage presence) as well as periodic large-scale 

disturbances (e.g., drought, flood, fire). In contrast, anthropogenic stressors tend to be 

more chronic in nature and can often lead to long-term environmental degradation 

associated with decreased biodiversity, reduced primary and secondary production, and a 

lowered ecosystem resiliency (i.e., ability of the ecosystem to recover to its original state 
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from perturbations).24. Several of the more important anthropogenic stressors are 

discussed below, with CWIS-related impacts considered as a separate category of stress. 

1. Habitat Loss 

Structural aquatic habitat is generally recognized as the most significant 

determinant of the nature and composition of aquatic communities. Most 316(b) facilities 

have been built on shoreline locations where power-generationindustrial buildings, 

roadways, canals, impoundments, and other water storage or conveyance structures have 

been constructed at the cost of terrestrial, aquatic, and wetland habitats. The main impacts 

of aquatic habitat loss are a reduction in the number of fish in the environment, a 

concentration of fishery spawning and nursery areas in fewer locations, shifts in species 

dominance based on available habitat and local extirpation of historical fish species. 

Habitat loss in shoreline areas exacerbates the effect of CWIS losses because many fish 

species affected by IM&E rely heavily on coastal wetlands as nursery areas. 

2. Water Quality and Impaired Waters 

Poor water quality is a major stressor of aquatic biota and habitats. Degraded 

surface water and sediment contaminants reflect both current and past industrial, 

agricultural and urban land use and disposal practices. Poor water quality can limit the 

numbers, composition, and distribution of fish and invertebrates; reduce spawning effort 

 

24 Rapport, D. J., & Whitford, W. G. (1999). How Ecosystems Respond to Stress. [Article]. BioScience, 

49(3), 193-203. See DCN 10-4871.
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and growth rates; select for pollution-tolerant species; cause periodic fishkills; or result in 

adverse bioaccumulative effects to piscivorous wildlife. 

EPA has determined that the majority of surveyed facilities, including 71 percent 

of electric generators and 79 percent of sampled manufacturing facilities, are within two 

miles of an impaired (i.e., CWA Sectionsection 303(d)-listed) waterbody.25 These 

impairments are caused by a variety of chemical, physical, and biological factors. These 

factors include biological stressors, nutrients, organic enrichment/loading, 

bioaccumulation, toxics, unknown causes, and other forms of anthropogenic sources of 

pollution (e.g., atmospheric deposition of mercury leading to fish advisories). The 

combined impacts of impaired water quality may result in highly degraded or altered 

aquatic communities that are further impaired by IM&E associated with the operation of 

regulated facilities. 

3. Overharvesting 

Overharvesting is a general term describing the exploitation of an aquatic 

population beyond a level that is sustainable, sometimes to the point of significantly 

reducing the population relative to historic levels. Given that many fisheries regulated by 

the National Marine Fisheries Service (NMFS) are overfished on a continual basis, 

overharvesting is a particular problem for stocks also subject to IM&E. 

 

25 Abt Associates, Inc. (2010). Source Water Body Comparisons (Under Work Assignment 2-09, Task 4) 

(pp. 13). Cambridge, MA. See DCN 10-4504.
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4. Invasive Species 

Non-indigenous invasive species (NIS) are a significant and increasingly 

prevalent stressor in both freshwater and marine environments. Approximately 300 NIS 

have become established in marine and estuarine habitats of the continental U.S., and the 

number of NIS continues to increase. Many NIS are nuisance species with undesirable 

effects on local communities.26 For example, interactions between NIS and other 

anthropogenic stressors can affect the colonization and distribution of native species 

subject to CWIS impacts. 

C. Effects of CWIS on Aquatic Ecosystems 

Multiple types of adverse environmental effects may be associated with CWIS 

operations at complying facilities. Many facilities employ once-through cooling water 

systems that impinge fishes and other aquatic organisms on intake screens. Impinged 

organisms may be killed, injured or weakened. In addition, early life stage fish or 

planktonic organisms can be entrained by the CWIS and subjected to high velocity and 

pressure, increased temperature, and chemical anti-biofouling agents in the system. These 

factors are highly lethal in most cases. Early life stages of larvae are highly sensitive and 

very unlikely to survive entrainment. Even if an organism is entrained as an egg and 

survives, its chances of surviving entrainment in the larvae stage are dramatically lower.

 

26 Ruiz, G. M., Fofonoff, P. W., Carlton, J. T., Wonham, M. J., & Hines, A. H. (2000). Invasion of Coastal 

Marine Communities in North America: Apparent Patterns, Processes, and Biases. [Article]. Annual 

Review of Ecology & Systematics, 31, 481-531. See DCN 10-4880.
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Thus, unless measures to protect larvae are in place, egg survival does not indicate that 

adverse environmental impacts have been avoided. EPA assumes for the purposes of a 

national rule that 100 percent of entrained organisms suffer mortality. 

The magnitude and regional importance of IM&E is a function of operational 

CWIS intake volumes and characteristics of the aquatic community in the region. Thus, 

for example, IM&E can contribute to impacts on T&Ethreatened and endangered (T&E)

species and reduce populations of ecologically critical aquatic organisms, including 

important organisms in an ecosystem’s food web. In addition, IM&E may diminish the 

compensatory reserves of populations’populations and reduce indigenous species 

populations, commercial fisheries, and recreational fisheries. Further, IM&E may stress 

overall communities and ecosystems, as evidenced by reductions in diversity or other 

changes in ecosystem structure or function. The direct and indirect impacts of CWIS may 

reduce other valuable ecosystem goods and services, including nutrient cycling and 

ecosystem stability. 

1. Losses of Fish from Impingement Mortality and Entrainment 

The most visible direct impacts of IM&E are the losses of large numbers of 

aquatic organisms, distributed non-uniformly among fish, benthic invertebrates, 

phytoplankton, zooplankton, and other susceptible aquatic taxa (e.g., sea turtles). These 

losses have immediate and direct effects on the population size and age distribution of 

affected species, and may cascade through food webs. 

In some cases, IM&E has been shown to be a significant source of anthropogenic 

mortality of depleted stocks of commercially targeted species. For example, 
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approximately 105.4 percent of the average annual recruitment toestimated A1E 

population of the Southern New England/Massachusetts stock of winter flounder 

(Pseudopleuronectes americanus) is lost to IM&E. 27 In addition to its effect on stocks of 

marine commercial fish species, IM&E increases the pressure on native freshwater 

species, such as lake whitefish (Coregonus clupeaformi) and yellow perch (Perca 

flavescens), whose populations have seen dramatic declines in recent years.28

IM&E is also likely to contribute to reduced population sizes of species targeted 

by commercial and recreational fishers, particularly for stocks that are being harvested at 

unsustainable levels and/or undergoing rebuilding. Thus, reducing IM&E may lead to 

more rapid stock recovery, a long-term increase in commercial fish catches, increased 

population stability following periods of poor recruitment and, as a consequence of 

increased resource utilization, an increased ability to minimize the invasion of exotic 

species.29

 

27 Terceiro, M. (2008). Southern New England/Mid-Atlantic winter flounder. In Northeast 

Fisheries Science Center (Ed.), Assessment of 19NEFSC) of the NOAA National Marine Fisheries 

Service. (2011). 52nd Northeast Groundfish Stock through 2007: Report of the 3rd 

GroundfishRegional Stock Assessment Workshop (52nd SAW): Assessment Review Meeting 

(GARM III) (pp. 2.457-452.528). Woods Hole, MA: Northeast Fisheries Science Center, 

U.S. Department of CommerceSummary Report. DCN 12-4940. 28 U.S. Department of the Interior (USDOI). (2004). Fisheries: Aquatic and Endangered Resources from 

http://www.glsc.usgs.gov/main.php?content=research_risk&title=Species%20at%20Risk0&menu=research 

[Retrieved June 23, 2004]; Wisconsin Department of Natural Resources (Wisconsin DNR). (2003). Adrift 

on the sea of life. Wisconsin Natural Resources, June, 17-21. See DCN 10-4914. 29 Stachowicz, J. J., & Byrnes, J. E. (2006). Species Diversity, invasion success, and ecosystem 

functioning: disentangling the influence of resource competition, facilitation, and extrinsic factors. Marine 

Ecology - Progress Series, 311, 251-262. See DCN 10-4892.
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2. IM&E Effects on Threatened and Endangered Species 

Populations of T&E (threatened and endangered) species may suffer increased 

mortality as direct or indirect consequences of IM&E. T&E species are vulnerable to 

future extinction or at risk of extinction in the near future and IM&E losses could either 

lengthen population recovery time, hasten the demise of these species, or counteract the 

effects of other conservation efforts. For this reason, the population-level and societal 

values of T&E losses are likely to be considered more important than the absolute 

number of losses that occur. Due to low population sizes, I&E mortality from CWISs 

may represent a substantial portion of the annual reproduction of T&E species. 

3. Thermal Effects 

One byproduct of once-through cooling water systems is a discharge of a heated 

effluent. Concerns about the impacts of heated effluents are addressed by state water 

quality standards addressing temperature., rather than a national rule. Section 316(a) of 

the Clean Water Act provides a mechanism for variances from controls that could be 

imposed due to thermal effects. Based on a limited review of NPDES permits, to the 

extent that facilities have controls on cooling water intake structures, these controls have 

been required to meet water quality standards related to temperature.30

 

30 Abt Associates, Inc. (2010). Source Water Body Comparisons (Under Work Assignment 2-09, Task 4) 

(pp. 13). Cambridge, MA. See DCN 10-4504.
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Thermal pollution has long been recognized as having multiple effects upon the 

structure and function of ecosystems.31 Numerous studies have shown that thermal 

discharges may substantially alter the structure of the aquatic community by modifying 

photosynthetic, metabolic, and growth rates32 and reducing levels of DO. Thermal 

pollution may also alter the location and timing of fish behaviors including spawning, 

aggregation, and migration, and may result in thermal shock-induced mortality for some 

species.33 Adverse temperature effects are likely to be more pronounced in aquatic 

ecosystems that are already subject to other environmental stressors such as high 

biochemical oxygen demand (BOD) levels, sediment contamination, and pathogens. 

Reduced waterbody volume due to the effects of climate change and/or lengthy droughts 

could exacerbate these effects. 

4. Chemical Effects 

The release of chemicals in the discharge of once-through cooling waters is 

another environmental effect associated with power plantindustrial facility operations. 

These chemicals include metals from internal corrosion of pipes, valves and pumps (e.g., 

chromium, copper, iron, nickel, and zinc), additives (anti-corrosion and anti-scaling 

 

31 Abt Associates, Inc. (2009). Summary of Ecological Effects of Thermal Discharge (pp. 28). Cambridge, 

MA. See DCN 10-4505. 32 Martinez-Arroyo, A., Abundes, S., González, M. E., & Rosas, I. (2000). On the Influence of Hot-Water 

Discharges on Phytoplankton Communities from a Coastal Zone of the Gulf of Mexico. Water, Air & Soil 

Pollution, 119(1-4), 209-230. See DCN 10-4820. 33 Smythe, A. G., & Sawyko, P. M. (2000). Field and laboratory evaluations of the effects of 'cold shock' on 

fish resident in and around a thermal discharge: an overview. Environmental Science & Policy, 3(S1), 225-

232. See DCN 10-4887.
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agents) and their byproducts, and materials from boiler blowdown and cleaning cycles. In 

addition to these pollutants, facilities also discharge anti-fouling biocide agents. 

A review of the effects of chemical treatment and discharge into the environment 

suggests that direct ecotoxicity in discharge plumes is rarely observed beyond the point 

of discharge or in a mixing zone near the pipe outlet.34 However, the presence of these 

chemicals in the receiving water may be additive to low-level chronic adverse effects 

from other anthropogenic stressors identified above. 

5. Effects of Flow Alteration 

The operation of CWISs and discharge returns significantly alter patterns of flow 

within receiving waters both in the immediate area of the CWIS intake and discharge 

pipe, and in mainstream waterbodies, particularly in inland riverine settings. In 

ecosystems with strongly delineated boundaries (i.e., rivers, lakes, enclosed bays, etc.), 

CWISs may withdraw and subsequently return a substantial proportion of water available 

to the ecosystem. Even in situations when the volume of water downstream of 

complyingregulated facilities changes relatively little, the flow characteristics of the 

waterbody, including turbulence and water velocity, may be significantly altered. 

Altered flow velocities and turbulence may lead to several changes in the physical 

environment. These changes can include sediment deposition, sediment transport, and 

 

34 Taylor, C. J. L. (2006). The effects of biological fouling control at coastal and estuarine power stations. 

Marine Pollution Bulletin, 53(1-4), 30-48. See DCN 10-4901.
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turbidity, each of which plays a role in the physical structuring of ecosystems.35 Flow 

velocity and turbulence are controlling biological factors in aquatic ecosystem health, and 

have been shown to alter feeding rates, settlement and recruitment, bioturbation, growth 

and population dynamics.36

Climate change is predicted to have variable effects on future river flow in 

different regions of the United States. Some rivers are expected to have large increases in 

flood flows while other basins will experience stress from low water levels. Thus, the 

adverse effects of flow alteration may increase or decrease over longer periods for larger 

rivers, depending on their location. 

D. Community–level or Indirect Effects of CWIS 

In addition to the direct effects of CWISs, IM&E may alter a wide range of 

aquatic ecosystem functions and services at the community level. Many of these effects 

on aquatic community function and service are poorly characterized, given the limited 

scope of IM&E studies and an incomplete knowledge of baseline or pre-operational 

conditions within affected waters. 

The operation of CWISs by generating facilities can lead to localized areas of 

depressed fish and shellfish abundance. Power plantsIndustrial facilities (and the intake 

volume they represent) are located in a non-uniform manner along coastlines and rivers. 

 

35, Hoyal, , D. C. J. D., Atkinson, J. F., Depinto, J. V., & Taylor, S. W. (1995). The effect of turbulence on 

sediment deposition. Journal of Hydraulic Research, 33(3), 349-360. See DCN 10-4797. 36 Sanford, E. B., Bertness, D., & M. D. Gaines, S. D. (1994). Flow, food supply and acorn barnacle 

population dynamics. Marine Ecology Progress Series, 104, 49-62. See DCN 10-4882.
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They may be clustered, such that the populations affected by IM&E are geographically 

heterogeneous. This can result in a highly localized and patchy distribution of aquatic 

organisms in regional areas. 

IM&E may directly reduce species populations through the death of individual 

organisms, or may indirectly affect species populations by altering established predatorprey relationships and thereby disrupting ecological niches and food webs. For example, 

the loss of young-of-year predators, such as striped bass, or loss of important forage fish, 

such as menhaden and bay anchovy, may affect trophic relationships and alter food webs. 

IM&E may lead to reductions in local community biodiversity or in a loss of genetic 

diversity in individual fish populations. Because IM&E represents a selective pressure on 

early life stages, it may reduce the genetic diversity of resident fish and prevent the 

recovery of depleted stocks.37 Also, because many stocks are differentiated by oceanic 

region and/or timing of migratory movements, IM&E could alter the seasonal migration 

and life cycle events of fish populations, which could have ramifications for predator 

species. 

IM&E may also alter the pace of nutrient cycling and energy transfer through 

food webs. Fish species have been shown to have substantial effects on nitrogen, 

 

37 Swain, D. P., Sinclair, A. F., & Mark Hanson, J. (2007). Evolutionary response to size-selective mortality 

in an exploited fish population. Proceedings of the Royal Society B: Biological Sciences, 274(1613), 1015-

1022. See DCN 10-4900.
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phosphorous, and carbon cycling due to storage and translocation effects.38 These 

alterations in nutrient cycling could lead to redirection of nutrient flows to other 

components of the ecosystem including water column phytoplankton, benthic macroalgae 

and attached epiphytes, with subsequent changes to the condition of critical ecosystem 

habitats, such as submerged aquatic vegetation. 

The effect of long-term or chronic IM&E may lead to a decrease in ecosystem 

resistance and resilience39 (i.e., ability to resist and recover from disturbance, including 

invasive species). That is, IM&E is likely to reduce the ability of ecosystems to withstand 

and recover from adverse environmental impactsthese ecosystem damages, whether those 

impacts are due to anthropogenic effects or natural variability. 

E. Cumulative Effects of Multiple Facilities 

Cumulative effects of CWISs are likely to occur if multiple facilities are located 

in close proximity and impinge or entrain aquatic organisms within the same source 

waterbody, watershed system, or along a migratory pathway of a specific species (e.g., 

striped bass in the Hudson River). EPA analyses suggest that approximately 20 

percentEPA analyses show more than 20 percent of all facilities on inland waters 

 

38 Vanni, M. J., Layne, C. D., & Arnott, S. E. (1997). "Top-down" trophic interactions in lakes: effects of 

fish on nutrient dynamics. Ecology, 78(1), 1-20. See DCN 12-5047. 39 Folke, C., Carpenter, S., Walker, B., Scheffer, M., Elmqvist, T., Gunderson, L., & Holling, C. S. (2004). 

Regime Shifts, Resilience, and Biodiversity in Ecosystem Management... Annual Review of Ecology, 

Evolution, & Systematics, 35(1), 557-581. See DCN 10-4770.
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withdraw more than 5 percent of the mean annual flow.40 See TDD Chapter 4.1.3 for 

detailed discussion. This impact is compounded because more than half of all regulated 

facilities are located on waterbodies with multiple CWISs. An inspection of the 

geographic locations of complyingregulated facilities (approximated by CWIS latitude 

and longitude) shows that that facilities in inland settings are more likely to be located in 

close proximity to other facilities (upstream or downstream) than are facilities in marine 

and estuarine environments. The cumulative impact of clustered facilities may be 

significant, due to the concentrated IM&E, combined intake flows, and the potential for 

other impacts such as thermal discharges. 

IV. Summary Description of the Final Rule 

Under today’s final rule, the owners or operators of existing facilities and new 

units at existing facilities are subject to BTA standards for impingement mortality and 

entrainment. that are expected to substantially reduce the adverse environmental impacts 

of cooling water intake structures. Earlier, in Section I, the preamble describes what 

facilities are subject to the rule. The discussion below presents an overview of the 

substantive requirements of the rule. 

 

40 As described in the Phase I proposed rule (65 FR 49060) and the Phase II NODA (66 FR 28853), absent 

any other controls, withdrawal of a unit volume of water from a waterbody will result in the entrainment of 

an equivalent unit of aquatic life (such as eggs and larval organisms) suspended in that volume of the water 

column. Thus, facilities withdrawing greater than 5 percent of the mean annual flow from freshwater rivers 

and streams may entrain equal proportions of aquatic organisms. 
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A. BTA Standard for Impingement Mortality for Existing Units at Existing 

Facilities

The final rule requires that existing facilities and new units subject to this rule 

must comply with one of the following seven alternatives identified in the national BTA 

standard for impingement mortality at § 125.94(c) (hereafter, impingement mortality 

standards): 

(1) operate a closed-cycle recirculating system as defined at § 125.92; 

(2) operate a cooling water intake structure that has a maximum through-screen 

design intake velocity of 0.5 fps; 

(3) operate a cooling water intake structure that has a maximum through-screen 

intake velocity of 0.5 fps; 

(4) operate an offshore velocity cap as defined at § 125.92 that is installed before 

[insertINSERT effective date of rule]; 

(5) operate a modified traveling screen41 that the Director determines meets the 

definition at § 125.92(s) and that the Director determines is the best technology available 

for impingement reduction; 

 

41 EPA is aware that innovative screen designs are currently being tested that are expected to provide 

similar or better performance than modified Ristroph traveling screems. Therefore EPA has defined 

modified traveling screen at 40 CFR 125.92 to mean any traveling water screen that incorporates the 

specified measures that are protective of fish and shellfish. In this preamble, modified traveling water 

screen with a fish handling and return system is often referred to more simply a modified traveling screen.
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(6) operate any other combination of technologies, management practices and 

operational measures that the Director determines is the best technology available for 

impingement reduction; or 

(7) achieve the specified impingement mortality performance standard. 

Options (1) , (2) and (4) above are essentially pre-approved technologies requiring 

no demonstration or only a minimal demonstration that the flow reduction and control 

measures are functioning as EPA envisioned. Options (3), (5) and (6) require more 

detailed information be submitted to the Director before the Director may specify it as the 

requirement to control impingement mortality. 

In the case of Option (3), which EPA considers to be a streamlined alternative, 

the facility must submit information to the Director that demonstrates that the maximum 

intake velocity as water passes through the structural components of a screen measured 

perpendicular to the screen mesh does not exceed 0.5 feet per second. 

In the case of Option (5), the facility must submit a site-specific impingement 

technology performance optimization study that must include two years of biological 

sampling demonstrating that the operation of the modified traveling screens has been 

optimized to minimize impingement mortality. As discussed below, if the facility does 

not already have this technology installed and chooses this option, the Director may 

postpone this study till the screens are installed (see VI.G.1.d below). 

In the case of Option (6), the facility must submit a site-specific impingement 

study including two years of biological monitoringdata collection demonstrating that the 

operation of the system of technologies, operational measures and best management 
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practices has been optimized to minimize impingement mortality. If this demonstration 

relies in part on a credit for reductions in the rate of impingement already achieved by 

measures taken at the facility, an estimate of those reductions and any relevant supporting 

documentation must be submitted. The estimated reductions in rate of impingement must 

be based on a comparison of the system to a once-through cooling system with a 

traveling screen whose point of withdrawal from the surface water source is located at the 

shoreline of the source waterbody. 

The impingement mortality performance standard in (7) requires that a facility 

must achieve an annuala 12-month impingement mortality performance of all life stages 

of fish and shellfish of no more than 2524 percent mortality, including latent mortality, 

for all non-fragile species that are collected or retained in a sieve with maximum opening 

dimension of 0.56 inches42 and kept for a holding period of 18 to 96 hours. The Director 

may, however, prescribe an alternative holding period. The annual12-month average of 

impingement mortality is calculated as the sum of total impingement mortality for the 

previous 12 months divided by the sum of total impingement for the previous 12 months. 

A facility must choose to demonstrate compliance with this requirement for the entire 

facility, or for each individual cooling water intake structure. Biological monitoring must 

be completed at a minimum frequency of monthly. 

 

42 Though less common, the EPA recognizes that 1⁄2 by 1⁄4 inch mesh are used in some instances and 

perform comparably to the 3/8 inch square mesh. Therefore, today’s rule allows for facilities to apply a 1⁄2 

by 1⁄4 inch sieve (diagonal opening of 0.56 inches) or a 3/8 inch sieve (diagonal opening of 0.53 inches) 

when discerning between impinged and entrained organisms. 
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The owner or operator of an existing facility must meet the impingement 

mortality requirements as soon as possiblepracticable after issuance of a final permit 

establishing the entrainment requirements under § 125.94(d). The owner or operator of a 

new unit at an existing facility must comply with the impingement mortality standard 

upon commencement of the new unit’s operation. 

Today’s final rule also allows the Director, based on review of site-specific data

and where no threatened or endangered species may be present, to conclude that a de 

minimusminimis rate of impingement exists and therefore no additional controls are 

warranted to meet the BTA impingement mortality standard. In addition, today’s final 

rule allows the directorDirector flexibility in determining appropriate site-specific 

controls that may be less stringent than those found at § 125.94(c)(1) to (7) for existing 

units at existing facilities that are used only in limited circumstances for emergency 

purposes. This provision can be found at § 125.94(c)(13) and the definition of 

“emergency purposes” can be found in the “Special Definitions” section at § 

125.92.operating with a capacity utilization of less than 8 percent averaged over a 24-

month block contiguous period. This provision can be found at § 125.94(c)(12). EPA 

notes that these provisions for impingement mortality would not apply to entrainment 

because, as discussed in the next section, the requirements for entrainment are established 

by the Director on a site-specific basis. 

B. BTA Standard for Entrainment for Existing Units at Existing Facilities

The final rule establishes the national BTA standard for entrainment at existing 

units at existing facilities at § 125.94(d) (hereafter, entrainment standards) for both 
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existing units and new units at existing facilities. In the case of existing). For such units, 

the rule does not prescribe a single nationally applicable entrainment reduction 

technologyperformance standard but instead 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 § 125.98(f)(2). 

Facilities that withdraw greater than 125 mgd AIF must develop and submit an 

Entrainment Characterization Study (§ 122.21(r)(9),)), as well as provide other 

information required at § 122.21(r)(7) and (10), (11), (12),) and (13) and, unless waived 

by the director, (11)) that must include specified data pertinent to consideration of several 

of the factors identified in § 125.98(f).

C. BTA Standards for Impingement Mortality and Entrainment for New Units 

at Existing Facilities 

The owner or operator of a new unit at an existing facility must achieve one of 

two compliance alternatives under the national BTA standards for impingement 

mortality and entrainment for new units at existing facilities at § 125.94(e) (hereafter, 

new units entrainment unit standards).43 Under the first alternative new unit entrainment 

 

43 New units are also subject to impingement requirements at § 125.94(b) but EPA expects that all new 

units will comply with these requirements through the installation of a closed-cycle cooling system, which 

is one of the compliantmost effective technologies identified in the final rule for reducing impingement and 
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standardstandards, the owner or operator of a facility must reduce AIF at 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. as defined at § 125.92(c)(1). The owner or operator of 

a facility with a cooling water intake structure that supplies cooling water exclusively for 

operation of a wet or dry cooling tower(s) and that meets the definition of closed-cycle 

recirculating system at § 125.92(c)(1) meets this new units entrainmentunit standard. 

Under the second alternative new units entrainmentunit standard, the owner or operator 

of a facility must demonstrate to the Director that it has installed, and will operate and 

maintain, technological or other control measures for eachthat reduce the level of adverse 

environmental impact from any cooling water intake atstructure used to supply cooling 

water to the new unit that achievesto a prescribed reduction in entrainment mortality of 

all stages of fish and shellfishcomparable level to that passwhich would be achieved

through a sieveflow reductions commensurate with a maximum opening dimension of 

0.56 inches. Like the Track II requirement in the earlier Phase I rulethe use of a closedcycle recirculating system. Under this alternative, the owner or operator of a facility must 

demonstrate entrainment mortality reductions that are equivalent to 90 percent or greater 

of the reduction that could be achieved through compliance with the first alternative 

entrainment standard for new units. 

 

impingement mortality. Therefore, the IM requirements for new units are already addressed by the new unit 

requirements by virtue of the first compliance alternative of the IM performance standard.
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The new unitsunit entrainment standards do not apply to certain water 

withdrawals, including (1) process water, gray water, waste water, reclaimed water, or 

other waters reused as cooling water in lieu of water obtained by marine, estuarine, or 

freshwater intakes; (2) cooling water used by manufacturing facilities for contact cooling 

purposes; (32) portions of those water withdrawals for auxiliary plant cooling uses 

totaling less than 2 mgd; (43) any volume of cooling water withdrawals used exclusively 

for make-up water at existing closed-cycle recirculating systems;44 and (54) any quantity 

of emergency back-up water flows. Furthermore, as is the case for existing units, 

obtaining cooling water from a public water system, using reclaimed water from 

wastewater treatment plants, or desalination plants, or using recycled process wastewater 

effluent as cooling water does not constitute use of a cooling water intake structure. The 

new unit requirements apply only to the volume of cooling water used by the new unit, or 

to the cooling water intake structures used by the new unit. The new unit requirements do 

not apply to the rest of the existing facility.

In addition, the Director may establish alternative entrainment requirements for 

new units when compliance with either of the two alternative new unitsunit entrainment 

standards would result in compliance costs wholly out of proportion to the costs EPA 

considered in establishing the requirements at issue or will result in significant adverse 

 

44 For facilities with a combination of closed-cycle recirculating systems and other cooling water systems, 

the entrainment mortality standard does not apply to that portion of cooling water withdrawn as make-up 

water for the closed-cycle recirculating system 
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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. Any Director-specified 

alternative must achieve a level of performance as close as practicable to the 

requirements of § 125.94(e)(1) or (2). 

CD. Other Provisions 

The final rule contains a number of other provisions related to the BTA 

impingement and entrainment reduction requirements. For example, the rule also 

provides that the Director may establish more stringent requirements as BTA if the 

Director determines that the facility owner or operator’s compliance with the 

requirements otherwise established under the final rule would not meet the requirements 

of applicable State and Tribal law, or other Federal law such as the Endangered Species 

Act.including water quality standards. 40 CFR § 125.94(i). Today’s rule also requires 

the owner or operator of a facility subject to this subpart to submit and retain permit 

application and supporting information as specified in § 125.95; monitor for compliance 

as specified in § 125.96; and report information and data and keep records as specified in 

§ 125.97. Director requirements are specified in § 125.98. 

The rule further provides that, in the case of a nuclear facility or a facility 

constructing or conducting maintenance on nuclear powered vessels of the Armed 

Services, if the owner or operator of the facility demonstrates to the Director, upon the 

Director’s consultation with the Nuclear Regulatory Commission, the Department of 

Energy or the Naval Nuclear Propulsion Program, that compliance with this subpart 
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would result in a conflict with a safety requirement established by the commissionthese 

entities, the Director must establish BTA requirements that would not result in a conflict 

with the Commission’s, the Department’s or the Naval Nuclear Propulsion Program’s

safety requirement. 

V. Summary of Most SignificantData Updates and Revisions to the Proposed 

Rule 

This description of revisions to the proposed rule is organized in three sections: 

data updates, regulatory approach and compliance, and new units. EPA published two 

NODAs (noticeNotice of data availabilityData Availability) (77 FR 34315, June 11, 

20112012 and 77 FR 34927, June 12, 2012) based on some comments received on the 

proposed rule and additional analyses. EPA also took public comment on the information 

in these notices. 

A. Data Updates 

On the basis of comments received, additional information made available, and 

further analyses, EPA revised a number of assumptions used in its assessments for the 

final rule. These included revisions to the engineering costs of options considered in 

development of the final rule, the information collection costs, the economic analyses, 

and the benefits analyses. The revised analyses, along with an explanation of how they 

affected decision making for this final rule, are discussed below. 

1. Impingement Data and Performance Standard 

Since publishing the proposal, EPA received a substantial number of comments 

regardingstating the limited amount of data used to develop the proposed impingement 
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mortality performance standard was too limited. EPA received more than 80 additional 

documents containing impingement and entrainment data. EPA reviewed these materials 

and, as a result, identified more than 40 distinct sets of additional impingement sampling 

and performance data. Many found that many documents did not provide useful data. For 

example, in some cases, a document did not provide useful information because the only 

data available were the facility name and raw sampling data for a number of different 

species of fish or shellfish, or both. In other cases, the documents focused on source 

water characterization data alone. However, after review, EPA identified more than 40 

distinct sets of additional impingement sampling and performance data.

EPA also reevaluated and revised the criteria it used in developing the standard 

for the proposal for including impingement mortality study data in the impingement 

mortality performance standard calculations. In calculating the impingement mortality 

performance standard of § 125.94(c)(7), EPA applied these revised criteria for acceptable 

data to both the new data and the earlier data used in developing the standard atfor

proposal. EPA’s approach for the final rule is similar to that of the proposal. In order to 

include data in EPA’s calculation, for the proposal, EPA applied the following four 

criteria. First, the data must be specific to the technology under consideration. Second, 

impingement mortality must have been reported as an absolute number or a percentage of 

impinged fish that were killed. Third, the data must reflect that the installed technology 

was operated under conditions that are representative of actual conditions at a facility, 

and fourth, the reported values must be actual measurements. EPA based the proposed
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performance standard on the performance of modified traveling screens with a fish return 

system using a limited definition of the control technology. 

In its reevaluation and based on comments, EPA decided to revise some of the 

criteria and add two new ones. In some cases, the effect of these changes is to relax the 

criteria and in others, to impose more restrictive criteria. First, all impingement data must 

be for non-fragile species (including shellfish). Second, the data must be representative of 

annual mortality data for purposes of deriving an annual performance standard. EPA 

notes that in contrast to the proposed rule, the permit application does not require 

submission of the proposed list of “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 may further cause confusion over existing Services or State requirements for 

such species. Further, 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. Instead, EPA is 

adopting the term “fragile species” and using the term exactly as it is used with the 

impingement mortality data and criteria used in calculating the impingement mortality 

performance standard of the rule. EPA included a definition for “fragile species” at § 

125.92,(m), as a species of fish or shellfish that has an impingement survival rate of less 

than 30 percent. EPA took this approach to ensure that a facility’s performance in 

reducing impingement mortality as demonstrated by collecting biological monitoringdata

would reflect only the effects of its improvements to the CWIS technology, and not be 

confounded by effects of monitoringdata collection that are not caused by impingement. 
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EPA also relaxed the holding time criteria as a result of reevaluating the range of 

acceptable impingement mortality holding times, which at proposal was limited to 24 to 

48 hours. After evaluating the data, EPA concluded that a range of holding times of 18 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. In contrast to the At proposal, EPA counted all fish 

that died at any time during the holding period, instead of excluding. For the final rule 

being promulgated today, EPA excludes those that were dead at time zero because such 

counts measured immediate deaths and not those organisms that were mortally harmed as 

a result of impingement. These counts also might reflect already injured, nearly dead, or 

already dead fish (“naturally moribund”) that were impinged by the screen. As a 

consequence of relaxing the holding times and other requirements, EPA based the 

performance standard on a larger set of data, with broader geographic representation. (For 

more information, see DCN 12-[XXX holding time memo].)-6703.) The rationale for 

these revisions to the data acceptance criteria are described in further detail in the TDD, 

Chapter 11. Using the revised criteria, EPA reviewed the data in each of the impingement 

mortality studies for potential inclusion in EPA’s evaluation of an impingement mortality 

performance standard. These changes resulted in an increase in the number of facility 

data sets acceptable for determining the impingement mortality performance standard, 

from four data sets at three facilities at proposal to 26 data sets at 17 facilities today. As a 

result, the annual12-month average impingement mortality performance standard of all 

life stages of fish and shellfish was revised from no more than 12 percent to no more than 
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2524 percent mortality, including latent mortality, for each non-fragile species that is 

collected or retained in a sieve with maximum opening dimension of 0.56 inches and kept 

for a holding period of 18 to 96 hours. The revised performance standard and data 

evaluation criteria are discussed in detail in sectionSection VI and Chapter 11 of the 

TDD. 

EPA also reevaluated theits approach to requiring numeric compliance monitoring 

for the impingement mortality performance standardsstandard. In particular, EPA 

considered the costs and burden of frequent biological monitoring for those technologies 

that, according to EPA’s record, perform equal to or better than the IM performance 

standard. As proposed, all facilities would have conducted weekly biological monitoring 

in perpetuity forirrespective of the compliance approach or technologies selected. EPA 

agrees with comments that this may be unnecessarily burdensome and of limited value 

for those technologies for which the potential performance is well documented. As 

discussed in the NODA (June 11, 2012; 77 FR 34321), EPA evaluated an alternative 

option where a two year study would be conducted to optimize the technology, after As 

such, today’s final rule includes seven compliance alternatives, only one of which the 

technology could be essentially viewed as a pre-approved technology without the need 

for further monitoring. EPA’s analysis of the option shows a facility would incur the 

same capital costs (in other words modified traveling screens would still be installed), 

would reducerequires biological compliance monitoring costs by at least 60 percent, and 

would potentially result in better performance than simply monitoring in perpetuity to 

demonstrate a minimum performance level. Second, by requiring the two-year study 
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during the same time biological studies are required with the permit application, overall 

biological monitoring costs would be reduced (for example, by only needing to mobilize 

the monitoring crew one time instead of twice). Third, by providing the Director the 

discretion to waive the performance optimization study in subsequent permit cycles in 

some cases (for example, when the facility operations and the source water body are 

substantially unchanged), the overall burden of biological monitoring would be reduced 

even further. For all of these reasons, the EPA has determined that a numeric monthly 

average impingement mortality performance standard is not necessary, and is not 

including a monthly limit in the final rule. .

EPA notes, however, that a facility relying in part on a credit for reductions in 

impingement mortality already obtained at the facility (§ 125.94(c)(6)),)) must 

conductgather biological monitoringdata at a minimum frequency of monthly for a period 

of two years in order to calculate their annual12-month average impingement mortality. 

Further, a facility choosing to comply using the impingement mortality performance 

standard (§ 125.94(c)(7)), must conduct biological monitoring at a minimum frequency 

of at least monthly in order to calculate their annualits 12-month average impingement 

mortality. The annual12-month average is calculated as the sum of total impingement 

mortality for the previous 12 months divided by the sum of total impingement for the 

previous 12 months. EPA is requiring that a facility choose to either demonstrate 

compliance with this requirement for the entire facility, or for each individual cooling 

water intake structure. The EPA expects that as the performance of the technology is 

demonstrated by the facility, the Director could reduce the frequency of biological 
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compliance monitoring. Further, prior to a subsequent permit application, a facility could 

collect sufficient performance data to demonstrate compliance with the IM performance 

standards to the satisfaction of the Director with thethat its “systems of technologies” 

compliance alternative. As a result, EPA expects no is BTA at that facility would be 

required to conduct biological compliance monitoring in perpetuity. 

2. Technology Costs 

Since publishing the proposal, EPA received a number of public comments from 

industry stating that EPA had underestimated the costs of modified traveling screens with 

fish returns. EPA used new information to revise the compliance cost estimates 

(including the methodology used for technology assignment) and the capital costs for 

several compliance technologies, including those used as the primary basis for the final 

rule. Those changes include the following: 

 In response to comments challenging EPA’s assumption that modified traveling 

screens were available at most facilities, EPA changed the assignment of the 

modified traveling cost module45 so as to apply this only where the existing intake 

for the model facility intake employed traveling screens. As a result, a number of 

intakes, such as those that use passive screens (e.g., fixed screens), were assigned 

 

45 EPA used a model facility approach to develop compliance technology costs where different sets of 

compliance technology cost algorithms called modules were assigned to individual model facility intakes 

on the basis of site-specific conditions. For a more detailed discussion, see the TDD Chapter 8. 
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higher cost technologies such as larger intakes or wedgewire screens with 

through-screen design velocities of 0.5 fps. 

 Because EPA has clarified that properly operated closed-cycle cooling meets 

BTA standardrecirculating systems is one of the compliance alternatives for 

impingement mortality, those intakes with existing closed-cycle cooling no longer 

receive additional impingement technology costs. 

 At proposal, the design of the larger intake module was based on a through-screen 

velocity of 1.0 fps and, therefore, was not consistent with the low velocity 

standardcompliance alternatives. To ensure that this technology will be consistent 

at all locations, the through-screen design velocity for the larger intake was 

changed to a maximum of 0.5 fps, resulting in a substantial increase in capital and 

operational and maintenance costs. 

 EPA received a number of comments noting that fish returns might be difficult to 

install at some intakes. EPA reviewed the fish return cost component of the 

modified traveling screen module and concluded that EPA’s costs represented an 

“easy” installation rather than an average of both easy and more difficult 

installation costs. To account for a wider range of fish return costs that includes 

those with higher costs, EPA increased the capital costs of the fish return 

component and included additional costs for those with particularly difficult 

circumstances such as very long intake canals and submerged offshore intakes. 

For a detailed discussion, see Chapter 8 of the TDD. 
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 EPA received a number of comments stating that it had underestimated capital 

costs for modified traveling screens. During site visits to several facilities, EPA 

obtained actual traveling screen replacement costs. EPA compared its estimates to 

actual reported replacement costs and vendor-supplied data and concluded that the 

capital costs were underestimated by about 20 percent. Therefore, EPA increased 

the capital costs of modified traveling screens by 20 percent. 

These changes to the engineering costs result in a 24% percent increase in capital 

and O&M costs. The revised costing assumptions are discussed in further detail in 

Chapter 8 of the TDD. 

3. Monitoring Costs for Impingement Mortality 

Many commenters expressed concern that requirements for monitoring for the 

impingement mortality performance standard were excessive. Of particular concern were 

the long-term costs for impingement mortality monitoring at facilities that would not be 

relying on either closed-cycle cooling or an intake velocity less than or equal to 0.5 fps 

through-screen design velocity. The final rule includes an alternative option to meetseven 

compliance alternatives for the impingement standard. ThisOne of these alternative

streamlines compliance and provides for reduced monitoring requirements for facilities 

employing modified traveling screens. This alternative is available if the facility has 

demonstrated the technology is optimized to minimize impingement mortality of all nonfragile species. Under this approach, EPA requires the facility to provide site-specific 

performance data to identify the operational conditions that will ensure that the 

technology is being operated optimally. Once these operational conditions have been 
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identified, the Director must include in the permit those operational measures and best 

management practices identified in the study and deemed as necessary by the Director to 

ensure proper operation of the modified traveling screens. EPA also clarified in the rule 

that compliance monitoring and reporting requirements for facilities that propose to 

comply with the impingement mortality standard by employing one of the alternative 

technological and operational impingement reduction approachespre-approved or 

streamlined IM compliance alternatives will be largely limited to information that ensures 

proper operation of the installed control technology. EPA estimates that this alternative 

approach will reduce in annual monitoring and reporting costs from approximately $47 

million under the proposed rule to approximately $27 million under the final rule. 

4. Benefits and Willingness to Pay Survey 

EPA received a number of comments on the proposed rule and NODA addressing 

the use of stated preference surveys to determine the public’s willingness-to-pay for 

benefits associated with the rule. EPA conducted a stated preference survey to calculate 

benefits associated with minimizing adverse impacts to aquatic ecosystems from cooling 

water intakes. For some commenters, the use of stated preference 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 stated preference surveys. For these reasons, EPA will 

obtain SAB review of the stated preference survey EPA conducted. The SAB review 

follows the external peer review EPA already conducted on the survey. SAB review will 

provide high caliber, independent professional judgment concerning the quality of the 
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survey done to date, including possible improvements EPA could make. EPA is also 

seeking SAB input on whether and how this survey could be used, as support for national 

rulemaking or NPDES permitting whenever benefit-cost analysis is considered. EPA 

expects that while this process will add time (it may take an additional year or more), 

given the importance of this issue for the evaluation of ecological benefits generally, it is 

worth taking the time to seek this additional input. Therefore, EPA will decide on any 

future use of the stated preference survey results after the SAB review is completed. 

EPA is committed to working with the states to support their site-specific permitting 

decisions with the benefit of the SAB review once it is completed. Based on 

consideration of public comment, 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. The rule does not require State Directors to require facility owners or operators 

to conduct or submit a willingness to pay survey to assess benefits. 

B. Regulatory Approach and Compliance 

1. Regulatory Approach 

EPA has largely adopted the regulatory approach of the proposed rule with 

several changes regarding compliance, particularly with respect to the impingement 

mortality standardsrequirements. These changes clarify elements of the rule (as discussed 

in the NODAs) about which commenters expressed uncertainty and provide additional 

flexibility to regulated facilities in meeting the rule’s impingement mortality standard. 

EPA received some comments questioning whether specific provisions apply to 

the entire facility or to individual intakes. To clarify this issue, EPA modified the rule 
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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, 

facilities may select different compliance strategies for different intakes, providing 

flexibility at facilities with multiple intakes. 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 low velocity standardcompliance alternative

of 0.5 fps on an individual intake basis. 

a. Impingement Mortality Standards 

EPA received a substantial number of comments requesting greater flexibility and 

clarification regarding compliance with the impingement mortality standards, including 

suggestions that (1) impingement requirements be addressed on a site-specific basis; (2) 

certain technologies should be pre-approved; (3) credit should be given for existing 

technologies and operating conditions; and (4) combinations of technologies be allowed. 

EPA has concluded that low-cost technologies for impingement mortality reduction are 

effective, widely available, feasible, and demonstrated for facilities nationally and thus, a 

completely site-specific approach is not necessaryappropriate. However, recognizing that 

for some sites technologies EPA has identified as representing BTA might not be 

available at all sitesother than modified traveling screens may allow a facility to achieve 

the same level of performance, EPA has included compliance options that provide for 
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more flexibility and allow consideration of the performance of combinations of 

technologies and operating conditions. Some of the more significant changes include the 

following: 

 Compliant technologies—EPA has concluded that employing certain technologies 

will meet or exceed the requirement of the impingement mortality standard, 

provided they meet certain design and operational criteria. These essentially preapproved and streamlined technologies include a closed-cycle 

coolingrecirculating system, existing offshore velocity cap, and maximum design 

intake velocity belowof 0.5 fps. Associated with these compliance options are 

reduced monitoring requirements. 

o Closed-Cycle Cooling—EPA has concluded that a fully closed-cycle 

recirculating system as defined at § 125.92(c) (and that is properly 

operated and maintained) achieves “best technology available” reductions 

inthe impingement mortality performance standard. Even after retrofitting 

a facility to be closed-cycle, it may still be possible to withdraw and 

discharge cooling water at rates associated with once-through cooling. 

Existing facilities that retrofit to closed-cycle cooling often do so without 

modifying or replacing their condenser to optimize it for closed-cycle 

operation. In such cases, the facility has an incentive to operate its system 

in a once-through cooling mode, to minimize chemical costs or avoid a 

turbine backpressure constraint. EPA has determinedconcluded that it is 

not appropriate to add conditions to the Phase I definition of closed-cycle 
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cooling because water may be withdrawn for purposes of replenishing 

losses to eliminiate this incentive.a closed-cycle recirculating system other 

than those due to blowdown, drift, and evaporation from the cooling 

system. However, the final rule provides the Director the discretion to 

determine whether the operation of a cooling system minimizes the makeup and blowdown flows withdrawn, consistent with the definition of a 

closed-cycle recirculating system (40 CFR 125.92(c)). 

o Existing Offshore Velocity Caps—The record indicates that an existing 

offshore velocity cap as defined at § 125.92(v) also achieves the necessary 

reductions in impingement mortality and is thus BTAmeets the IM 

standard. Data in the record concerning existing velocity caps show that a 

velocity cap alone is insufficient, but data on existing offshore velocity 

caps shows that a velocity cap in combination with their current offshore 

locations meet EPA’s BTA performance standard for impingement 

mortality. EPA has determined that new offshore velocity caps could 

comply using the combination of technologies approach in § 125.94(c)(6). 

The offshore component likely makes the velocity cap technology 

unavailable except to facilities in marine waters and certain Great Lakes 

locations; therefore, the technology alone is not BTA. 

o Through-Screen Velocity—EPA has clarified that compliance with thea

0.5 fps intake velocity standard alone is BTA for impingement 

mortalityachieves the IM standards. EPA’s record shows an intake 
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velocity of 0.5 fps or lower provides similar or greater reductions in 

impingement, and therefore impingement mortality, than modified 

traveling screens – the technology forming the basis for the numeric 

impingement mortality limitperformance standard that is the goal for all 

facilities. There are two ways to demonstrate compliance using intake 

velocity. First, an intake with a maximum design through-screen intake 

velocity less than or equal to 0.5 fps is pre-approved BTA for 

impingement mortality and does not require further monitoring. 

Alternatively, under a streamlined option, the facility may demonstrate to 

the Director that the facility meets the velocity requirement through 

monitoring of the actual intake velocity. Screen velocity can be monitored 

by direct measurement or by calculation using the volumetric actual intake 

flow and source water surface elevation. 

 Modified Traveling Screens—A facility must operate modified traveling screens46

that the Director determines meets the definition at § 125.92.(s). Facilities will 

demonstrate that they have optimized performance of their traveling screen to 

minimize IM. 

 

46 While rotary screens are technically not modified traveling screens, the regulation at §125.92(s) defines 

modified traveling screens to include traveling water screens that incorporate measures protective of fish 

and shellfish. EPA has thus provided the flexibility for other types of active screens that achieve the same 

or better performance than modified traveling screens. 
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 Systems of Technologies asto Meet the BTA for IM Standard—EPA received a 

substantial number of comments asking whether previously installed technologies 

or various combinations of technologies and operating conditions could also meet 

the BTA standard for impingement mortality. For example, some technologies, 

such as louvers, reduce the rate of impingement, but the effect on overall 

impingement mortality reduction cannot easily be measured and would not appear 

in biological sampling of the technology. In EPA’s view, the Director should take 

into account the reduction in impingement – for example, that associated with 

such technologies as louvers or behavioral deterrents, or due to intake location – 

when determining permit conditions to include in the facility’s permit in order for 

a combination of technologies to achieve the required impingement mortality 

standards to include in the facility’s permit. Thus, the facility should obtain credit 

toward the impingement mortality standard for such reductions in the rate of 

impingement. A number of the flexibilities above were described in the June 11, 

2012 NODA, and EPA has included a provision to allow additional flexibility in 

achieving compliance through the use of a combination of technologies and 

operating conditions. A facility may use a system of technologies, management 

practices and operational measures to achieve the impingement mortality 

standard, including, for example, flow reductions, seasonal operation, unit 

closures, credit for intake location, behavioral deterrent systems, and other 

technologies and operational measures. The Director must determine, based on a 

demonstration by the facility to the Director, that the system of technologies or 
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operational measures, in combination, have been optimized to minimize 

impingement mortality of all non-fragile species. The Director may require 

additional operational measures, best management practices, and monitoring as 

part of the demonstration. In addition, the facility’s permit must include 

conditions to ensure that the facility operates its cooling water intake structures in 

a manner consistent with the conditions and measures identified in its 

demonstration to the Director. 

 Numeric IM LimitPerformance Standard—As a practical matter, EPA expects 

that very few facilities will choose to comply with the numeric impingement 

mortality performance standard. Those facilities that do choose to comply in this 

way will need to demonstrate to the Director how the technology the facility is 

implementing enables the facility to meet the impingement mortality standard. 

The numeric limitstandard provides a pathway to compliance for innovative 

technologies that may be developed in the future. 

EPA also received many comments stating that barrier nets were both 

unnecessary and might be unavailable in many locations. Because EPA’s revised 

impingement data set had sufficient data to characterize shellfish impingement, EPA has 

eliminated the barrier net requirement in the final rule. See Section VI for more 

information.

b. Definition of Closed-Cycle Cooling System 

In the final rule, EPA revised the definition of a closed-cycle recirculating system 

to provide additional flexibility for the Director in determining which closed-cycle 
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cooling systems comply with the IM&E performance standards. The proposed rule’s 

definition of “closed-cycle recirculating systems” included, as elements of a properly 

operated closed-cycle system performance, requirements generally expressed in terms of 

cycles of concentration (COC) or percentage flow reduction relative to a once-through 

cooling system. 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 are in recirculated water relative to make-up water, and thus 

how longwell 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. 

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. Some commenters stated that, while they have been operating as closedcycle units for many years, they were concerned that their facilities would not be “closedcycle 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 
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for closed-cycle cooling. EPA found in site visits many complex manufacturing facilities 

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. 

EPA carefully considered these issues and concluded that in most cases, facilities 

should qualify as 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 a threshold, while retaining the minimized 

makeup flow aspect of the definition. As an example, in the case of a facility that uses 

make-up water from a freshwater source, a Director may determine that a closed-cycle 

recirculating systems under performance measures in the proposed definition. To address 

any residual situations where the COC definition does not work, EPA revised the 

definition for the final rule to providesystem 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 
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minimum cycles of concentration of 3.0. And likewise, in the case of a facility that uses 

make-up 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 

“generally” will achieve prescribed percentage can generally be deemed to minimize 

make-up and blowdown flows if it reduces actual intake flows (AIF) by 94.9 percent as 

compared to a once-through cooling system or if its cooling tower is operated at a 

minimum cycles of concentration of 1.5. These reductions or minimumand cycles of 

concentration are illustrative. A Director may determine that other levels near these 

numbers could also constitute a closed-cycle recirculating system. The final rule, 

however, further recognizes that in certain unavoidable circumstances, these 

specifiedlevels for COC or percent flow reduction values 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. If a facility demonstrated that such site-specific circumstances were responsible 

for the facility’s failure to achieve the benchmarks, theSuch 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 even ifwhen the 

benchmarks are not met. 
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In cases where the Director will make a determination as to whether the facility’s 

cooling system meets the definition of a closed-cycle recirculating 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. To avoid misuse of this provision, 

the Director will make the final determination. 

Finally, 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 make-up 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 closed-cycle 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 Section VI for further 

discussion. 

c. 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 

entrapment requirements were not well defined and would require costly technologies not 

considered in EPA’s cost estimates. Moreover, in the commenters’ view, the 
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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, a facility that entraps fish must count the 

entrapped organisms as impingement mortality.EPA agrees that in some cases, such as 

where a canal or basin for maintaining consistent water levels is located behind the 

CWIS, that the proposed entrapment requirement could require additional controls such 

as additional fish returns that are not, in all cases, feasible. For example, EPA found in 

site visits that the forebay may be located more than a mile from the CWIS, and a fish 

return in that situation would not have been feasible. The final rule deleted the 

requirement that prohibited entrapment. In the final rule, facilities would account for all 

impinged fish and shellfish when conducting their two 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, under § 125.94(c)(8).

d. Requirements for Threatened and Endangered Species 

 EPA consulted with the Fish and Wildlife Service and National Marine Fisheries 

Service, as required by the Endangered Species Act, and EPA made a number of 

adjustments to the rule specific to the protection ofprotect threatened and endangered 

species and designated critical habitat as a result. of the consultation; the protections 

were included to insure that the rule is not likely to jeopardize the continued existence of 

listed species or result in the destruction or adverse modification of designated critical 
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habitat. To be clear, the ESA provisions of the rule extend to all listed T&E species, not 

just fish and shellfish. See Section VIII.K for a summary of these provisions. 

2. Compliance Timelines for Impingement Mortality and Entrainment Requirements

Timelines

At proposal, compliance deadlines for impingement mortality and entrainment 

requirements were set separately. Facilities would have been required to meet 

impingement mortality reduction requirements as soon as possible, but no more than 

8eight years after the effective date of the rule. Compliance with entrainment reduction 

requirements would have been set by the Director. Many commenters expressed concern 

that the compliance timeline for the impingement mortality and entrainment requirements 

should be harmonized to prevent a facility from having to install a technology to comply 

with impingement mortality requirements, only to be required at a later date to install an 

entrainment reduction technology that effectively renders the investment in the 

impingement mortality technology obsolete or worthless. 

EPA agrees that facilities required to install both impingement and entrainment 

compliance technologies will benefit from reduced compliance costs if the compliance 

scheduling is coordinated. EPA also agrees that requiring more timely decisions on 

entrainment requirements than anticipated at proposal will facilitate these cost savings 

without sacrificing fish protection. Thus entrainment requirements must be written into 

all permits issued in 2017 and beyond. In some cases, impingement compliance can be 

attained with entrainment technologies. For example, the Director may determine that the 

installation of modified fine-mesh traveling screens and narrow-slot wedgewire screens 
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will achieve the impingement mortality standard and further, that this same equipment 

represents, on a site-specific basis, BTA entrainment control. If the compliance schedule 

is not harmonized, it is possible that a facility could install (at significant cost) coarsemesh traveling screens that it might have to later retrofit with fine-mesh panels. It is also 

possible that a facility could make modifications necessary to attain a 0.5-fps throughscreen velocity to meet the IM standards and later have closed-cycle cooling identified as 

BTA for entrainment, thereby making the intake modifications for impingement control 

unnecessary. 

To address this issue in the final rule, EPA revised the compliance requirements 

so that the Director is required first to establish entrainment requirements under § 

125.94(b)(1) in the final permit. The facility will then be required to comply with the 

impingement mortality standard in § 125.94(c) as soon as possible thereafterpracticable 

thereafter. See Section VIII on implementation for more detailed discussion. 

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. 

C. New Units 

EPA has revised the definition of new units to include repowered units where 

both the steam turbine and condenser are replaced, except where the new units are high 

energy efficiency units. For more details, see Section I. 

EPA has revised the definition of new units to mean a stand-alone unit at an 

existing facility the construction of which is commenced after the effective date of 
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today’s final rule; consists of only a stand-alone unit constructed at an existing facility; 

and that does not otherwise meet the definition of a new facility at § 125.83. A standalone unit is a new, separate unit that is constructed at an existing facility. New unit 

includes stand-alone units that are added to a facility for purposes of the same general 

industrial operation as the existing facility. A new unit may have its own dedicated 

cooling water intake structure, or may use an existing or modified cooling water intake 

structure. 

VI. Basis for the Final Regulation 

In response to the Supreme Court’s decision in Entergy Corp. v. Riverkeeper, Inc. 

et al. in April 2009, and the Second Circuit decision in Riverkeeper II, EPA has 

reevaluated the requirements for existing facilities under CWA section 316(b). As 

discussed above, EPA collected additional data and information to update both its 

assessment of the efficacy of various technological measures for reducing IM&E 

costsand analyses prepared for the earlier rule-making efforts. TheEPA’s additional 

technical rigor provided a strengthened EPA’s analysis of BTAdifferent technologies for 

reducing IM and their effectiveness. As a result of its revised assessments and further 

consideration of the factors affecting the availability of closed-cycle recirculating 

systemsdifferent technology in a wide range of settings, EPA has decided not to repromulgate requirements for existing facilities that mirror those of the final Phase II rule. 

InsteadFurther, EPA is adopting, for the reasons explained in detail below, a new 

framework. In addition, as previously noted, EPA decided to address all existing facilities 
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subject to section 316(b) in this rule (i.e., combiningboth those subject to the Phase II rule 

and partssome of those subject to the Phase III rule). For a brief description of the final 

rule, see Section IV.

A. EPA’s Approach to BTA 

CWA section 316(b) requires EPA to establish standards for cooling water intake 

structures that reflect the “best technology available for minimizing adverse 

environmental impact.” As explained above, the statute is silent with respect to the 

factors that EPA should consider in determining BTA, but courts have held that section 

316(b)’s reference to CWA sections 301 and 306 is an invitation for EPA to look to the 

factors47 considered in those sections in establishing standards for section 316(b). 

But EPA, when considering such factors, is not bound to evaluate these factors in 

precisely the same way it considers them in establishing effluent limitations guidelines 

under CWA section 304. As the Supreme Court noted, given the absence of any factors 

specified in section 316(b), EPA has much more discretion in its standard setting under 

section 316(b) than under the effluent guidelines provisions. Therefore, the statute vests 

EPA haswith broad discretion in determining what is the “best” technology that is 

“available” for minimizing adverse environmental impact. TheAs the Supreme Court has 

 

47 The factors specifically delineated in CWA sections 301 and 306 that EPA may consider include cost of 

the technology, taking into account the age of the equipment and facilities, process employed, engineering 

aspects associated with a particular technology, process changes and non-water quality environmental 

impact (including energy requirements). 
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further explained that, under section 316(b), the “best” technology “available” may 

reflect a consideration of a number of factors and that “best” does not necessarily mean 

the technology that achieves the greatest reduction in environmental harm that the 

regulated universe can afford. Rather, the “best” (or “most advantageous,” in the court’s 

words) technology may represent a technology that most efficiently produces the 

reductions in harm. 

EPA interprets section 316(b) to require the Agency to establish a standard that 

will best minimize impingement and entrainment—the main adverse effects of cooling 

water intake structures not otherwise addressed by the other sections of the CWA (e.g., 

thermal discharges). In EPA’s view, several important considerations underpin its 

decision. First, its BTA determination should be consistent with, and reflective of, the 

goals of CWA section 101: “to restore and maintain the physical, chemical, and 

biological integrity of the Nation’s waters,” with the interim goal of “water quality which 

provides for the protection and propagation of fish, shellfish, and wildlife and provides 

for recreation in and on the water.” 

Second, E.O. 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)). In selecting a 

regulatory approach, agencies, to the extent permitted by law, must tailor regulations to 
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impose the least burden on society and, in choosing among regulatory alternatives, 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. 76 FR 3821 (January 21, 2011). Because the 

Supreme Court has concluded that the CWA authorizes EPA to consider costs and 

benefits in its BTA determination, EPA has consequently considered costs and benefits in 

this final rule as directed by the President. In accord with E.O. 13563, EPA has 

concluded that the benefits of the selected option for the final rule justify its costs. For 

additional discussion, see sectionSection VI.F below. 

EPA has also considered the costs and the benefits of the different technologies it 

evaluated for BTA. Consideration of benefits is complicated by the debate about the tools 

and data that would permit a complete expression of ecological benefits in monetized 

terms. EPA has, however, 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 (see sectionSection X below). 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.transfer was based on a species that represents less than one 

percent of adverse environmental impacts. EPA is continuing to refine its tools to develop 

a more complete analysis concerning benefits for future application. 
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In selecting the “best” technology available for minimizing adverse 

environmental impact, EPA looked at a number of factors. As discussed previously, 

EPA’s initial approach to 316(b) standard setting was similar to one it follows in 

considering a technology-based rule under sections 301, 304, and 306. EPA first 

considered the availability and feasibility of various technologies, their costsand then 

evaluated costs associated with these technologies (including potential costs to facilities 

and households), and thetheir economic impacts associated with these technologies.. EPA 

also reviewed the efficacyeffectiveness of these technologies in reducing impingement 

mortality and entrainment. Further, EPA also considered additional factors set out in 

CWA section 304(b), including location, age, size, and type of facility. In addition, 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 establishing a rule that includes ain 

the case of the BTA standard for impingement mortality, EPA based the standard on 

theperformance of well-operated modified traveling screens with a fish handling and 

return system. A as defined more specifically by the rule. Under the BTA IM standard, a 

facility has severala number of options for compliance. In the case of the BTA standard 

for entrainment, on the other hand, EPA could not identify one technology that 

represented BTA for existing facilities on a national basis.
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B. Overview of Final Rule Requirements 

As noted, EPA concluded that the best technology available for minimizing 

impingement mortality was “modified traveling screens,” as more specifically defined in 

the rule. The BTA Impingement Mortality Standard includes seven technology options 

for complying with the standard whose performance is equivalent to, or better performing 

than modified traveling screens. First, the rule identifies four technologies (closed-cycle 

recirculating systems, reduced design intake velocity, reduced actual intake velocity, and 

existing offshore velocity caps) that reduce impingement mortality as well or better than 

the technology EPA reviewedmodified traveling screens, and therefore will generally 

comply with the impingement requirementsBTA Impingement Mortality Standard of 

today’s final rule. 

The rule also provides that, if the Director determines that modified traveling 

screens are insufficient to protect shellfish, the Director may establish additional 

measures under § 125.94(c)(8) such as seasonal deployment of barrier nets, or if modified 

traveling screens48 are insufficient to protect other species, the Director may establish 

additional protective measures under § 125.94(c)(9). In addition, the rule provides in 

125.94(g) that the Director may establish additional control measures and monitoring or 

reporting requirements in the permit in order to protect Federally-listed threatened and 

endangered species and designated critical habitat. The Director may include such 

 

48 Or any of the IM compliance alternatives. 
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conditions that are designed to minimize incidental take, reduce or remove more than 

minor detrimental effects to Federally-listed species and designated critical habitat or 

avoid jeopardizing Federally-listed species and or destroying or adversely modifying 

designated critical habitat (e.g., prey base). 

Next, the final rule provides an option that allows a facility to demonstrate to its 

permitting authority that it has installed travellingmodified traveling screens – the 

technology EPA identified as the basis for the BTA impingement mortality standard --–

and to provide data on the performance of its screens. The facility must demonstrate that 

its modified traveling screens are consistent with EPA’s definition and demonstrate 

through an impingement technology performance optimization study that its screens have 

been optimized to minimize impingement mortality. After consideration of the 

information provided, the permitting authority will determine whether the technology is 

BTAthe best technology available for impingement mortality reduction at the site and 

include permit conditions to ensure optimal performance of the screens. In other words, 

the owner or operator of a facility will be deemed to be in compliancecomply with the 

BTA standardsstandard for IM at § 125.94(c)(5) if that facility uses modified traveling 

screens as defined at § 125.92,(s), and operates in accordance with the permit conditions 

established by the Director that ensure the technology will perform as demonstrated. If 

the Director determines that the modified traveling screens are insufficient to protect 

shellfish, the Director may establish additional measures for shellfish under § 

125.94(c)(9) such as seasonal deployment of barrier nets, or if the Director determines 

that the modified traveling screens are insufficient to protect fragile species, the Director 
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may establish additional measures under § 125.94(c)(11) such as behavioral technologies. 

HoweverAs noted above, in certain circumstances, under § 125.94(c)(8), (9) and 

125.94(g), the Director may require additional protective measures. 

As stated in the June 11, 2012 NODA, 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 retrofitting to 

closed-cycle cooling (see Exhibit VIII-1).The, showing expected compliance alternative 

based on technologies in place today). If a facility chooses to comply with the BTA IM 

standard by installing and operating traveling screens, the screens must meet the 

definition of modified traveling screens provided at § 125.92, which includes, but is not 

limited to(s). These may include, for example, 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. EPA based thisthe regulatory definition on the 

commonly found features of modified traveling screens used in developing the BTA 

impingement mortality performance standard. 

In addition, the final rule also provides a compliance option that would allow 

facilities with the option of demonstrating to the Director on a site-specific basis, similar 

to the showing for travellingmodified traveling screens, that a system or combination of 

technical and operational measures will representachieve the BTA standard for 

impingement reductionmortality at a particular site. TheUsing a combination of technical 

and operational measures as the basis for demonstrating compliance allows facilities the 

opportunity to take credit for intake location, flow reduction, or other measures already 
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employed to reduce the rate of impingement. Further, the combination of technical and 

operational measures provides the flexibility to use a system of approaches to reducing 

impingement and impingement mortality. This may include technologies that were not 

found to reduce impingement consistently or in all circumstances, but that on a sitespecific basis such technologies may have been demonstrated to provide a high level of 

performance. For example, a facility might employ light and sound to induce an 

avoidance response from certain species. This might not alone address impingement 

mortality for all non-fragile species at the intake, therefore additional measures (intake 

location, barrier nets, etc.) would also be applied, to minimize the rate of impingement or 

impingement mortality. 

For both the screens and system of technologies, a two year study must be 

completed in which biological monitoringdata collection is used to make site-specific 

adjustments to screens or the combination of technologies in order to optimize 

performance at that facility. Those optimal operating parameters then become permit 

conditions. For facilities that have already installed traveling screens or the technologies 

associated with the system approach, EPA has combined the two year biological study 

with the other permit application and rule requirements for biological monitoringdata 

collection, including the source water baseline biological and entrainment 

characterizationsSource Water Baseline Biological Characterization Data. In this manner, 

EPA is establishing a consistent set of biological study requirements, with an overall 

reduction in the burden of the required level of biological monitoring. 
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Lastly, a facility canmay choose to comply with the numerical impingement 

mortality performance standard that was established based on the BTA technology. If a 

facility chooses this compliance option, it must conduct periodic monitoring to 

demonstrate compliance. Under this last compliance option, a facility could implement 

innovative technologies to address impingement mortality and subsequently demonstrate 

that their performance is as good as, or better than, a modified traveling screen with fish 

handling and return system. EPA envisions that after a sufficient demonstration period of 

a technology’s performance, the facility will be able to qualify its operation under the 

previous option. 

For entrainment, on the other hand, EPA could not identify one technology that 

represented BTA for allexisting facilities on a national basis, for the reasons explained in 

detail below. Instead, the national BTA entrainment standards for existing facilities 

establishes a detailed regulatory framework for the determination of BTA entrainment 

requirements by the permitting authority on a site-specific basis. 

While site-specific permit requirements are not new, what is different about this 

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 in the permit application, prescribes procedures that the Director must follow 

in its decision making and factors that must be considered in determining what 

entrainment controls will represent the BTA and associated requirements are BTA on a 

site-specific basis. 
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As previously noted, EPA looked at a number of factors in considering what 

national entrainment standard it should adopt. In addition to those general considerations 

discussed above,As discussed in detail in the following section, EPA identified only one 

high performing technology as a potential BTA candidate for entrainment: closed-cycle 

recirculating systems as defined at § 125.92(c)(1). While there are other technologies for 

entrainment that are available or demonstrated, they are not uniformly high performing 

technologies. See TDD Chapter 6 for more information regarding the lack of 

intermediate performing technologies for entrainment. EPA has identified the following 

specific factors as the key elements in its decision not to prescribe a singlethis technology 

as the basis for a national BTA determinationstandard for entrainment: land availability, 

air emissions permits, and remaining useful plant life. How these factors dictated EPA’s 

decision is discussed below. 

For new units at existing facilities, EPA has established BTA requirements to 

minimize impingement mortality and entrainment, based on flow reduction 

commensurate with closed-cycle cooling. The rest of this chaptersection describes in 

detail the above considerations.

BC. Technologies Considered to Minimize Impingement and Entrainment 

As described in Chapter 4 of the TDD, power plants and manufacturers withdraw 

large volumes of cooling water daily. Cooling water withdrawals are responsible for over 

half of surface water withdrawals for all uses in the United States, including agriculture 

and municipal uses. The purpose of thesecooling water withdrawals is to dissipate that 
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portion of the heat that is a by-product of industrial processes that facilities have not 

harnessed to a productive end and therefore view as waste heat. 

Increasing thermal efficiency of the industrial processes is perhaps the best way to 

reduce cooling water demands, and hence the adverse environmental impacts that result. 

The majority of environmental impacts associated with intake structures are 

caused by water withdrawals that ultimately result in the loss of aquatic organisms. These 

losses might be from impingement, entrainment, or both. Impingement occurs when 

organisms are trapped against the outer part of a screening device of an intake structure.49

The force of the intake water traps the organisms against the screen and they are unable 

to escape. Not all organisms in the incoming water are impinged, however. Some might 

pass through the screening device and travel through the entire cooling system, including 

the pumps, condenser or heat exchanger tubes, and discharge pipes. This is referred to as 

entrainment. Various factors lead to the susceptibility of an organism to impingement or 

entrainment. For more detailed discussion of impingement and entrainment and the 

associated mortality and other effects, see sectionSection III above. 

For purposes of this rule, EPA is adopting the following definitionsconventions

for defining impingement and entrainment and mortality: 

 

49 Typically, cooling water intake structures use various screening devices to prevent objects (e.g., debris, 

trash) from being drawn in with the cooling water and ultimately clogging or damaging the cooling water 

system, especially the condenser or heat exchanger components. 
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 Impingement: Occurs when any life stage of fish and shellfish are pinned against 

the outer part of an intake structure or against a screening device during intake 

water withdrawal. Impingement may also occur when an organism is near a 

screen but unable to swim away from the intake structure because of the water 

velocity at the intake. 

 Entrainment: Occurs when any life stages of fish and shellfish are drawn into the 

intake water flow entering and passing through a cooling water intake structure 

and into a cooling system. 

 Impingement Mortality: The death of fish or shellfish due to impingement. It may 

also include organisms removed from their natural ecosystem and lacking the 

ability to escape the cooling water intake system and thus subject to mortality. 

Note that impingement mortality need not occur immediately. Impingement may 

cause harm to the organism which results in mortality at some time after 

impingement. For purposes of this rule, EPA has defined impingement mortality 

as the death of those organisms collected or retained by a sieve with a maximum 

opening of 0.56 inches; this includes both the 3/8-inch sieve and a 1⁄2-inch by 1⁄4-

inch mesh.50

 Entrainment Mortality: The death of fish or shellfish due to entrainment. This is 

typically associated with mortality related to small organisms that pass the entire 

 

50 Mesh sizes of 3/8” are commonly referred to as coarse mesh; this refers to the size of the screen opening 

(in contrast to fine mesh) and not the roughness of the mesh material. 
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way through a facility and are killed as a result of thermal, physical, or chemical 

stresses. This term also includes the death of those fish and shellfish that may 

occur on fine mesh screens or other technologies used to exclude the organisms 

from entrainment. For purposes of this rule, EPA defined entrainment mortality as 

the death of those organisms passing through a sieve with a maximum opening of 

0.56 inches. 

Impingement mortality is typically less than 100 percent of the impinged 

organisms. if a fish return or backwash system is employed. Impingeable organisms are 

generally not very small fish ofor early life stages (e.g., those that can pass through 3/8 

inch mesh screens), but typically are fish with fully formed scales and skeletal structures 

and well-developed survival traits such as behavioral responses to avoid danger. EPA’s 

data demonstrate that, under the proper conditions, many impinged organisms can 

survive. 

Entrainable organisms generally consist of eggs and early life stage larvae. Early 

larvae generally do not have skeletal structures, have not yet developed scales, and in 

many cases are incapable of swimming for several days after hatching. EPA has found 

that entrainable organisms that are collected after interaction with the CWIS 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].) Therefore, 

without entrainment control, entrainment is assumed to lead to entrainment mortality. 
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Also see Chapter A7 of the Phase II Regional Studies Document (DCN 6-0003; EPAHQ-OW-2002-0049-1490). 

Whether an organism near a cooling water intake structure is impinged or 

entrained is a function of the screen mesh size. Holding the number and size distribution 

of organisms at the intake constant, a larger screen mesh size will result in relatively 

more entrainment, while a smaller mesh size will result in relatively more impingement. 

Historically, traveling screens deployed by power plants used a 3/8-inch mesh size. For 

this reason, most studies and reports referring to impingement are in fact referring to 

those organisms impinged on a 3/8-inch mesh screen. Similarly, entrainable organisms 

are those organisms fitting through a mesh of less than or equal to 3/8 of an inch. This 

also means the majority of entrainable organisms are composed of eggs, larvae, and 

smaller juveniles. More recent studies, particularly those that evaluate mesh sizes smaller 

than 3/8 of an inch, continue to refer to impingement as any organism caught on the 

screen. This can cause some confusion because many organisms that would have been 

entrained with a 3/8-inch mesh instead become impinged by the finer mesh. These are 

referred to as impinged entrainables or “converts.” EPA has also found that most studies 

of entrainment are biased toward the larger (older) larvae with higher survival rates and 

do not analyze survival of smaller larvae. This bias implies a focus on larvae body 

lengths sufficient to have begun scale and bone development, and it generally reflects the 

more motile early life stages. EPA found that these study findings cannot be applied to 

smaller and less motile life stages, which are incapable of avoidance responses. It is also 

important to note that preventing entrainment by some exclusion technologies might 
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result in very high entrainment reductions by converting entrainment to impingement, but 

these impinged organisms may have an even lower likelihood of surviving impingement 

than larger potentially impinged organisms. Therefore, while entrainment refers 

specifically to passage through the cooling water intake system, entrainment mortality 

also includes those smaller organisms killed by exclusion from the cooling water intake 

system. Today’s rule uses the 3/8-inch mesh size as part of the definition of impingement 

mortality and entrainment mortality as a means of clearly differentiating those organisms 

that might be susceptible to impingement or entrainment, and thereby avoids any 

confusion over the status of impinged entrainables or “converts.” 

Generally, two basic approaches can be used to reduce impingement mortality and 

entrainment. The first approach is flow reduction, where the facility installs a technology 

or operates in a manner to reduce or eliminate the quantity of water being withdrawn. 

Reduced volumes of cooling water produce a corresponding reduction in impingement 

and entrainment and, therefore, reduced impingement mortality and entrainment

mortality. It should be noted that, at electric generators, flow reduction could be 

achieved, perhaps most effectively, by installing more energy efficient production, 

thereby requiring less cooling per unit of electricity generated. The second way to reduce 

impingement and entrainment is to install technologies or operate in a manner that either 

(1) gently excludes organisms or (2) collects and returns organisms without harm. 

Exclusion technologies or practices divert those organisms that would have been subject 

to impingement and entrainment away from the intake. Collection and return 
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technologies are installed to collect and return organisms to the source water, allowing 

impingement to occur but possibly preventing impingement mortality. 

Although not available to all facilities, two other approaches to reducing 

impingement and entrainment are (1) relocating the facility’s intake to a less biologically 

rich area in a water bodywaterbody, and (2) reducing the intake velocity. Relocating an 

intake farther from shore or at greater depths can be effective at entrainment reduction 

but is not generally available to many inland facilities because the distance or depths 

required to reach less biologically-productive waters are not generally available. Further, 

while a far offshore intake may exhibit a lower density of organisms, the species found 

will change as a function of distance from the shoreline as well as depth in the water 

column. Therefore, it may not always be desirable to relocate an intake structure. A 

reduced intake velocity provides motile organisms the opportunity to swim away from 

the intake structure. This approach can be very effective in reducing impingement but has 

no effect on entrainment. 

The sectionSections 1 and 2 below further describes flow-reduction and exclusion 

technologies. 

1. Flow Reduction 

Flow reduction is commonly used to reduce impingement and entrainment. For 

purposes of this rulemaking, EPA assumes that entrainment and impingement (and 

associated mortality) at a site are proportional to source water intake volume. Thus, if a 

facility reduces its intake flow, it similarly reduces the amount of organisms subject to 
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impingement and entrainment.51 Some common flow reduction technologies are variable 

frequency drives and variable speed pumps, seasonal operation or seasonal flow 

reductions, unit retirements, use of alternate cooling water sources, water reuse, and 

closed-cycle cooling systems. For additional detailed information on these technologies 

as well as others, see Chapter 6 of the TDD, “California’s Coastal Power Plants: 

Alternative Cooling System Analysis” (DCN 10-6964), and EPRI’s “Fish Protection at 

Cooling Water Intake Structures: A Technical Reference Manual” (DCN 10-6813). 

a. Variable Frequency Drives and Variable Speed Pumps 

A facility with variable speed drives or pumps operating at their design maximum 

can withdraw the same volume of water as a conventional circulating water pump. 

However, unlike a conventional circulating water pump, variable speed drives and pumps 

allow a facility to reduce the volume of water being withdrawn for certain periods. The 

pump speed can be adjusted to reduce water withdrawals when cooling water needs are 

reduced, such as when ambient water temperatures are colder (and therefore capable of 

 

51 Impingement rates are related to intake flow, intake velocity, and the swimming ability of the fish subject 

to impingement. Entrainment is generally considered to be proportional to flow and therefore a reduction in 

flow results in a proportional reduction in entrainment, as EPA assumes for purposes of national 

rulemaking that entrainable organisms are uniformly distributed throughout the source water. EPA has 

consistently applied this assumption throughout the 316(b) rulemaking process (for a discussion of 

proportional flow requirements in the Phase I and II rules see, e.g., 66 FR 65276 and 69 FR 41599; also see 

EPA’s 1977 draft guidance manual for 316(b), available at DCN 1-5045-PR from the Phase I docket) and 

continues to assume that it is broadly applicable on a national scale and is an appropriate assumption for a 

national rulemaking. EPA recognizes that this assumption does not necessarily apply when relocating or 

varying the time pattern of withdrawals, such that these may be effective strategies to reduce impingement 

and entrainment in some locations. 
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dissipating more heat), when fewer generating units are operating or when fuel is more 

efficiently burned. In site visits, EPA found that variable drives and pumps were typically 

used at units operating below capacity, such as load -following units. EPA estimates that 

facilities with intermittent water withdrawals could achieve a 5 to 10 percent reduction in 

flow.52 For this reason, mostmany baseload generating units and continuously operated 

manufacturing processes will obtain minimallimited reductions in flow from using these 

technologies. EPA is further aware that some facilities may need to withdraw water for 

cooling even while the facility is not in production, such as facilities on standby status, or 

nuclear facilities where the heat energy generated by fission must still be dissipated while 

the facility is out of service. As a result, EPA determined that variable frequency drives 

and variable speed pumps, while useful in specific setting and circumstances, are not 

BTA candidates because the flow reduction technologies with generalhave limited

application and availability, and are not a high performing technology as an entrainment 

control measure. 

b. Seasonal Operation or Seasonal Flow Reductions 

Seasonal operation or seasonal flow reduction refers to the reduction or 

elimination of a quantity of water withdrawn either during periods of low demand for 

electricity output, or to coincide with certain biologically important periods. Most 

facilities that currently employ seasonal flow reductions do so to limit thermal impacts or 

 

52 Withdrawals of colder water could allow facilities to reduce their intake flow using variable drives and 

pumps, but EPA does not have data on the efficacy or availability of this approach. 
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to reduce entrainment, because entrainment often has a peak season, particularly during a 

localized spawning season. local spawning season. Freshwater drum, for example, 

perform broadcast spawning during early summer when water temperatures reach about 

65 degrees Fahrenheit. 

During specific peak entrainment periodsImpingement is generally more sporadic, 

less predictable, and more difficult to address with seasonal operation. For example, 

clupeid species experience impingement episodes sporadically all throughout the winter 

and spring. Largemouth bass, on the other hand, can spawn in the late spring, which thus 

begins a season of potentially high entrainment for this species. During this specific peak 

entrainment period, a facility could scale back its operation (or perhaps not operate at all), 

thereby reducing or eliminating the volume of cooling water withdrawn. This could be 

accomplished through a combination of variable speed pumps or shutting down some 

portion of the pumping system. Seasonal flow reduction could also consist of operating a 

closed-cycle coolingrecirculating system as defined at § 125.92(c)(1) as once-through 

during part of the year and as a closed-cycle system during the peak entrainment season. 

(EPA notes that closed-cycle cooling has been rejected as noted in the previous section, 

and discussed in more detail below.) Facilities could also choose to schedule regular 

maintenance to occur during these high entrainment periods. These maintenance 

activities often require the facility to reduce or cease operations and can be timed to 

coincide with the most biologically productive periods. Through site visits, EPA gathered 

information on species present at facilities and has identified some sites where 

entrainment appears to be significant all year long, and other sites where peak 
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entrainment occurs in as few as three to four months of the year.53 However, if all powergenerating facilities in a local area were to stop operating at the same time, there could be 

difficulty in supplying electricity to the area. Therefore, EPA concluded that seasonal 

operations have limited nationwide application for controlling entrainment and are thus 

not widely available entrainment reduction technology. 

Impingement is generally more sporadic, less predictable, and more difficult to 

address with seasonal operation. For example, clupeid species, such as gizzard shad, 

experience impingement episodes sporadically throughout the winter and spring during 

periods of especially cold water temperatures, or sporadically throughout the summer and 

fall during periods of low dissolved oxygen. 

c. Unit Retirements 

Some power plants units have been retired and others have essentially ceased all 

operations but have not been formally retired or decommissioned. ReasonsThe reasons

for their inactivity vary,54 but the end result is the facility no longer needs cooling water 

withdrawals for these units. Similarly, manufacturers may retire processing units as 

market demand changes, process lines are moved to other sites, or production 

technologies change. Unit closures provide clear reductions in flow, but the demand for 

 

53 See DCN 10-6702 and its attachments for examples of spawning “seasons.” 

54 Note that some generating units are retired by the owner (i.e., the unit is no longer considered sufficiently 

profitable to operate) or is rarely dispatched by its independent system operator for market-driven reasons 

(i.e., the unit cannot deliver at a competitive price). except during limited peak seasons; see also § 

125.94(c)(12)). They may also be mothballed, placed on cold storage, or maintained in various other states 

of operational readiness. 
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electricity (or other products) might dictate that production be increased at the facility in 

question or at another facility altogether; there is usually no guarantee that the intake flow 

will be permanently retired. EPA expects flow reductions due to unit closures could be 

reasonably included as part of a facility’s impingement mortality and entrainment 

reductions strategy. Given the number of variables involved in the decision to retire a unit 

and the likelihood of a facility having a unit that is ready to retire at promulgation of the 

final rule, unit retirements are not a nationally available entrainment reduction measure.

See Section VIII for further discussion of how a facility can take credit for flow 

reductions attributable to unit closures.

d. Use of Alternate Cooling Water Sources 

While not reducing the overall usage of water at a facility, using an alternate 

source of cooling water can reduce impingement and entrainment if the alternate source 

substitutes for withdrawals from surface waters. An example is using “gray” water as a 

source of cooling water, such as a facility that reaches an agreement with a nearby 

wastewater treatment plant to accept the wastewater treatment plant’s effluent as a source 

of cooling water.55 Such alternate sources are limited by available capacity and 

consistency of flow. Increasing competition for these sources of water may make this a 

more challenging approach for existing facilities than for new facilities that are not yet 

 

55 See, for example, EPA’s site visit report for PSEG’s Linden Generating Station (DCN 10-6557), which 

has a capacity of 1230 MW, 35% percent CUR, and uses 7-8 mgd of gray water as the sole source of 

makeup water for its cooling towers. 
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fixed in location. In principle, alternate sources could be used to fulfill either a fraction or 

all of a facility’s cooling water demands. In practice, the location of alternate sources, the 

costs of moving water from the alternate source to the facility, and whether the facility 

uses a once-through or closed-cycle coolingrecirculating system as defined at § 125.92(c)

will determine whether the alternate source can meet all or a portion of the facility’s 

cooling water needs. All these factors limit the widespread availability of alternate 

cooling water sources as an entrainment reduction measure, however use of alternative 

sources of cooling water such as wastewater treatment effluent could be attractive for 

certain facilities where the cost of retrofitting or other site-specific circumstances are 

favorable. [NOTE to reviewers: EPA would like to cite here as support for this material 

the draft DOE report on “U.S. Energy Sector Vulnerabilities to Climate Change and 

Extreme Weather” when it is public.]56

e. Water Reuse 

Typically associated with manufacturing facilities, water reuse (defined as using 

water for multiple processes) can reduce the volume of water needed for cooling, process, 

or other uses. For example, a facility might withdraw water for non-contact cooling water 

and then reuse the heated effluent as part of an industrial process. In effect, the facility 

 

56 For maps showing which electric generators are near a source of available reuse water for cooling, see 

Tidwell, V., J. Macknick, K. Zemlick, J. Sanchez, and T. Woldeyesus. 2013. “Transitioning to Zero 

Freshwater Withdrawal for Thermoelectric Generation in the United States.” (submitted). See also the 

accompanying presentation given at the American Geophysical Union Fall 2012 Meeting available at 

http://www.nrel.gov/docs/fy13osti/57444.pdf.). 
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has eliminated the need to withdraw additional water for the latter process. EPA has 

observed significant water reuse at manufacturing facilities but has not developed 

national level data for such reuse because of the range of different manufacturing sectors 

and the significant variability in manufacturing processes appropriate for reuse. For 

example, during site visits, EPA observed that it may be difficult to quantify specific 

water reuse at complex facilities. (See, for example, the site visit report for ArcelorMittal, 

a steel mill at DCN 10-6551.) For additional detail on water usage in specific industrial 

sectors, see Chapters 4 and 8 of the TDD. 

 Increasingly, electric utilities are adopting water reuse to meet a portion or 

all of their cooling water demands. Water reuse can enhance the reliability of power 

generation in water-limited environments. Given the complex use (and reuse) patterns for 

some facilities and the lack of reuse at other facilities, water reuse cannot be considered 

as a widely available entrainment reduction option. 

f. Closed-Cycle Cooling Systems 

Closed-cycle cooling systems allow a facility to transfer its waste heat to the 

environment using significantly smaller quantities of water relative to once-through 

cooling –, and in some cases no water. The main types of closed-cycle cooling systems 

are wet cooling, dry cooling, hybrid cooling, and impoundments. Each is described 

below. 

i. Wet Cooling Systems 

In a wet cooling system, cooling water that has absorbed waste heat transfers that 

heat through evaporation of some of the heated water into the surrounding air and 
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recirculates the now cooled water to continue the cooling process.57 This process enables 

a facility to reuse the remaining water, thereby reducing the quantity of water that must 

be withdrawn from a water bodywaterbody. Because the heat is transferred through 

evaporation, the amount of water withdrawn from the water source is greatly reduced, 

though not eliminated completely, because make-up water is required to replace that lost 

through evaporation and blowdown.58 The two main types of wet cooling systems are 

natural draft and mechanical. While wet cooling systems reduce withdrawals 

significantly relative to once-through systems, they can increase the consumptive use of 

water because they rely on evaporation (which is not returned to the water 

bodywaterbody) for heat dissipation. When once-through cooling is used and 

withdrawals are a significant portion of the source water bodywaterbody, the return of 

heated water might contribute to greater evaporation from the water bodywaterbody

relative to the water body’swaterbody’s normal evaporation rate. EPA does not have 

conclusive data on the relative magnitude of these effects, but the data do suggest that the 

relative difference in evaporation is not so great that it will play a major role in 

determining a cooling system type in most watersheds. EPA examined available 

information on evaporation losses in DCN 12-[XXX],-6673, including a comparison to 

 

57 In addition, a smaller portion of the heat is also removed through direct contact between the warm water 

and the cooler surroundings; this is known as sensible heat. 

58 Cooling towers must replace water lost to evaporation; this is referred to as makeup water. Additionally, 

as water evaporates, dissolved solids and other materials gradually increase in concentration in the 

circulating water and can cause operational difficulties. To minimize these issues, cooling tower operators 

continually discharge a small portion of the circulating flow and replace it with makeup water; this is 

referred to as blowdown. 
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evaporative losses from the downstream effluent plume of once-through cooling systems. 

While EPA recognizes that evaporative losses from closed-cycle systems are greater, 

EPA’s analysis does not suggest that the difference is substantial enough to outweigh the 

significant reduction in adverse environmental impacts to aquatic organisms. However, 

the relative loss of water through evaporation for closed-cycle and once-through systems 

is site-specific, depending on the exact design of the systems. 

There are two common designs for wet cooling systems. A natural draft cooling 

tower can be as tall as 500 feet and has a hyperbolic shape. The height of these towers 

creates a temperature differential between the top and bottom of the tower, which creates 

a natural chimney effect that transfers heat as heated water contacts rising air. In contrast, 

mechanical cooling towers rely on motorized fans to draw air through the tower and into 

contact with the heated water.59 These towers are much shorter than natural draft cooling 

towers (typically 30 to 75 feet tall) and can be built in groups. Mechanical cooling towers 

may require more land area than natural draft cooling towers for an equivalent amount of 

cooling. Both types of towers require electricity for pumps, but mechanical draft towers 

also require electricity to operate the fans. In both cases, the electricity need of the towers 

reduces an electric generating facility’s net generating output. Thus, the monetary and 

environmental costs of this reduction in energy efficiency must be considered. These 

 

59 Modular cooling tower units provide an additional cooling tower alternative. Modular cooling towers 

resemble mechanical cooling towers, but are portable, typically rented for short-term periods and quickly 

assembled. 
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environmental costs include human health and welfare effects from increased air 

emissions (from burning additional fuel to make up for the power that cannot be sold) 

and the global climate change effects of increased greenhouse gas output at fossil-fueled 

plants.facilities (these costs are now explicitly considered in the benefit-cost analysis; see 

Section X below). Both natural draft and mechanical cooling towers can operate in 

freshwater or saltwater environments. Saltwater applications typically require more 

make-up water than freshwater applications, making them less efficient in reducing water 

withdrawals. Optimized cooling towers can achieve flow reductions of 97.5 and 94.9 

percent or better for freshwater and saltwater sources, respectively. 

ii. Dry Cooling Systems 

Dry cooling systems virtually eliminate the need for cooling water withdrawals.60

Unlike wet cooling systems, waste heat in dry cooling systems is transferred completely 

through convection and radiation, rather than evaporation. Direct dry cooling is much like 

a car radiator; turbine exhaust steam passes through tubes or fins for cooling, and the 

condensate is returned to the boiler to be reheated into steam to propel the turbine. The 

system is completely closed to the atmosphere, and there is no contact between the 

outside air and the steam or the resulting condensate. Because of the heavy reliance of 

 

60 Dry cooling systems blow down some of the circulating water in the cooling system to prevent the 

buildup of materials in the condenser. However, the volume of makeup water is extremely low—a dry 

cooling system typically reduces intake flows by 98–99 percent over a comparable once-through cooling 

system. 
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dry cooling on ambient air temperatures and the lower efficiency of heat transfer through 

convection and radiation, dry cooling systems are much larger and therefore more 

expensive61 than wet cooling systems for a given cooling load. While dry cooling systems 

are not uncommon in the U.S. (see DCN 10-6943), they have typically been built at 

smaller generating units or in areas where limited water supplies might make uncertain 

the availability of either once-through cooling or wet cooling make-up water, such as the 

arid southwestern United States. Dry cooling has not been used for circulating water 

cooling at nuclear facilities. 

iii. Hybrid Cooling Systems 

In certain applications, a facility could choose a hybrid cooling system design that 

incorporates elements of both wet and dry cooling. Typically, the base of the tower 

functions as a wet cooling system and the upper portion as a dry cooling system. The 

most common reason for this design is to reduce the visible plume of water vapor, which 

is accomplished by recapturing some of the water vapor evaporated in the wet portion of 

the tower. This design is also usually much shorter than natural draft wet towers and can 

also include plume abatement controls. Another version of the hybrid cooling system also 

includes both wet and dry cooling sections, but the dry section functions to directly cool a 

 

61 The construction and capital costs for dry cooling towers have been reported as fivefour to 10 times more 

expensive as wet cooling towers, and the auxiliary power consumption for dry cooling is higher than for 

wet cooling. See DCN 10-6679. EPA recognizes that costs for dry cooling may have decreased since this 

document was written, but costs for dry cooling are still markedly higher than those for wet cooling. The 

other challenges associated with dry cooling remain unchanged. 
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portion of the turbine exhaust steam. The benefits of such a tower may include substantial 

water savings as well as reduction in power plant efficiency losses associated with just 

dry cooling. 

iv. Impoundments 

Impoundments are surface waterbodies that serve as both a source of cooling 

water and a heat sink. As with cooling towers, impoundments rely on evaporative cooling 

to dissipate the waste heat; a facility withdraws water from one part of the 

pondimpoundment and then discharges the heated effluent back to the 

pondimpoundment, usually in another location to allow the heated water time to cool. 

Depending on local hydrology, impoundments may also require makeup water from 

another waterbody. Impoundments can be man-made or natural, and can be offset from 

other water bodies or as part of a “run of the river” system (the latter are sometimes 

referred to as cooling lakes). As discussed in section V above, EPA recognizes that not 

all impoundments are part of a closed-cycle cooling system.

2. Exclusion and Collection Technologies 

Over the last several decades, numerous technologies in addition to specific flow 

reduction measures such as velocity controls and closed-cycle cooling have been 

developed in an effort to minimize impingement mortality and entrainment associated 

with cooling water intake systems. The following section summarizes the most widely 

used technologies and the most effective and best-performing technologies, such as 

screens, barrier nets, aquatic filter barriers, and collection and return systems. For 
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additional detailed information on these technologies and others, also see Chapter 6 of the 

TDD, “California’s Coastal Power Plants” report (DCN 10-6964) or EPRI’s “Fish 

Protection at Cooling Water Intake Structures” report (DCN 10-6813). 

a. Screens 

There are several types of screens that offer protection that are discussed below, 

including travellingtraveling screens and cylindrical wedgewire screens. Not described in 

this section are fixed screens that are used simply for the purpose of debris exclusion but 

do not offer protection to fish, larvae, and eggs. 

i. Traveling Screens 

Traveling screens are a technology in place as part of most cooling water intake 

structures. These screens originally were designed to prevent debris from entering the 

cooling water system, but they also prevent some fish and shellfish from entering the 

cooling water system. Traveling screens have been installed in a wide variety of 

operating and environmental conditions: salt water, brackish water, freshwater, and icy 

water, as well as river, lake and tidal applications. On the basis of the technical survey, 

EPA found 93 percent of electric generators and 73 percent of manufacturers employ 

traveling water screens or other intake screens. Many types of traveling water screens 

(e.g., through flow, dual flow, center flow) are used. The most common design in the 

United States is the through flow system. The screens are installed behind bar racks (trash 

racks) but in front of the water circulation pumps. The screens rotate up and, while out of 

the water, debris and impinged organisms are removed from the screen surface by a highpressure spray wash. Screen wash cycles are triggered either manually or by a certain 
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level of head loss across the screen (indicating clogging). By definition, this technology 

works by collecting (i.e., impinging) fish and shellfish on the screen. Ideally, traveling 

screens would be used with a fish handling and return system, as discussed below. The 

return system should be regularly maintained to prevent biofouling or other blockages 

that may affect survival. 

ii. Cylindrical Wedgewire Screens 

Unlike traveling screens, cylindrical wedgewire screens are a passive intake 

system. Wedgewire screens, also called “V” screens or profile screens, consist of 

triangular-shaped wires arrayed on a cylindrical framing system, with long slots between 

the wires, lengthwise along the screen. Slot sizes for conventional traveling screens 

typically refer to a square opening (3/8 inch by 3/8 inch) that is punched, molded, or 

woven into the screen face. Wedgewire screens are constructed differently, however, with 

the slot size referring to the distance between longitudinally adjacent wires. These 

screens are designed to have a low through-slot velocity (less than 0.5 fps or 0.15 meter 

per second) and typically have smaller slot sizes than a coarse mesh traveling screen. The 

entire wedgewire structure is submerged in the source water bodywaterbody. (See 

Chapter 6 of the TDD for an illustration of these screens.) 

When necessary conditions regarding placement in the water bodywaterbody are 

met, these screens exploit physical and hydraulic exclusion mechanisms to achieve 

consistently high impingement reductions, and as a result, impingement mortality 

reductions. Wedgewire screens require an ambient crossflow current to maximize the 

sweeping velocity provided by the water bodywaterbody. The screen orientation allows 
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the crossflow to carry organisms away from the screen allowing them to avoid or escape 

the intake. Lower intake velocities also allow fish to escape from the screen face. 

Entrainment reductions can also be observed when the screen slot size is small enough 

and intake velocity is low enough to exclude egg and larval life stages.62 Limited 

evidence also suggests that extremely low intake velocities can allow some egg and larval 

life stages to avoid the intake because of hydrodynamic influences of the crossflow. 

Therefore, performance is dictated largely by local conditions that are further dependent 

on the source water body’swaterbody’s biological composition. Costs of wedgewire 

screens increase significantly as slot size and design intake velocity decrease because the 

cumulative size of the screen (or number of screens) must grow in order to accommodate 

the same flow of cooling water. Wedgewire screens can also employ cleaning and deicing 

systems such as air-burst sparging to help maintain open intake structures and low intake 

velocities. 

According to data from the industry questionnaire, EPA’s site visits, and industry 

documents, dozens of facilities across the United States employ cylindrical wedgewire 

screens. However, wedgewire screens are not feasible for all facilities, particularly where 

intakes are in shallow water or have limited shoreline frontage. Also, wedgewire screens 

might not be feasible where the size and number of wedgewire screens would interfere 

with navigation of vessels. As described above, locations also need to have an adequate 

 

62 Note that this is entrainment exclusion and not necessarily related to the survival of entrainable 

organisms. 
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source water sweeping velocity. Most of the performance data for wedgewire screens is 

based on coarse mesh slot sizes with an intake velocity of 0.5 fps. Because it is extremely 

difficult to measure impingement and entrainment reductions in the field, most 

performance data for wedgewire screens is based on barge and lab studies.63 EPA does 

not have data on the performance of fine mesh wedgewire screens on entrainment 

survival. Consequently, EPA has considered wedgewire screens only for impingement 

mortality. For additional discussion of the specific design and operation of cylindrical 

wedgewire screens, see Chapter 6 of the TDD. The following section discusses the 

importance of mesh size to impingement mortality and entrainment reductions. 

iii. Screen Mesh Size Considerations 

Coarse Mesh 

Coarse mesh traveling screens are the typical traveling screen fitted on the 

majority of cooling water intakes. A large number of facilities have intake screens with 

3/8-inch (9.5 mm) mesh panels.64 This size mesh is common because, as a general rule, 

the maximum screen slot size is never larger than one-half of the condenser tube diameter 

(the condenser tubing is the narrowest point in the cooling water system and, as such, is 

most susceptible to clogging from debris), and this tubing is typically 3/4 or 7/8 inch in 

 

63 EPA expects that properly designed wedgewire screens have a design intake velocity of 0.5 fps, therefore 

intakes with wedgewire screens will meet the impingement standard at § 125.94(c)(2) and there is no need 

to separately “pre-approve” this technology likeas in the remanded 2004 Phase II rule. 64 In today’s rule the EPA recognizes that 1⁄2 by 1⁄4 inch mesh is used in some instances and perform 

comparably to the 3/8 inch square mesh. 
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diameter. Mesh of 3/8-inch (roughly 9.5 mm) size does not prevent entrainment and 

without any other precautions can lead to high mortality of impinged fish. Coarse mesh 

traveling screens have been in use by both power plants and manufacturers for more than 

75 years and represent the baseline technology. Similarly, the majority of successful 

wedgewire installations are coarse mesh. 

Fine Mesh 

Fine mesh traveling and wedgewire screens are similar to coarse mesh screens. 

The only difference is the size of the screen mesh. Fine mesh traveling screens have been 

in use since the 1980s. Typically, facilities have incorporated fine mesh in an effort to 

reduce entrainment. The mesh size varies, depending on the organisms to be protected, 

but typically range from 0.5 to 5 mm. Data in the record demonstrate that entrainment 

typically decreases as mesh size decreases. Slot sizes larger than 2 mm do not prevent 

eggs from passing through the screen. Converting traveling screens from coarse mesh to 

fine mesh often requires adding more screens in order to maintain the same flow, since 

the open area of a fine mesh screen is less than the open area of a coarse mesh screen. 

Adding more screens is one way to maintain that flow.65 EPA estimates that as many as 

17 percent of existing intakes could not be enlarged to accommodate a 2 mm mesh, and 

as many as 55 percent of existing intakes could not accommodate a 0.5 mm slot size 

under conditions of low-intake velocities. For these reasons, fine mesh screens are 

 

65 A facility could also increase its intake velocity. 
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available for some locations, but they are not the best performing technology and are not 

an available technology for the industry as a whole for IM&E. For more details, see 

Chapter 6 of the TDD. 

b. Barrier Nets 

Barrier nets are nets that fully encircle the intake area of water withdrawal, from 

the bottom of the water column to the surface, and prevent fish and shellfish from coming 

in contact with the intake structure and screens. According to data from the industry 

questionnaire (as of the year 2000), at least a half dozen facilities employ a barrier net. 

Typically, barrier nets have large mesh sizes (e.g., 1/2-inch or 12.7 mm)66 and are 

designed to prevent impingement. Because of the large mesh size, they offer no reduction 

in entrainment. They are often deployed seasonally, wherever seasonal migrations create 

high impingement events or to avoid harsh winter conditions that jeopardize integrity of 

the net. Barrier nets also prevent impingement of shellfish on the intake traveling screen. 

Shellfish such as crustaceans can pose a unique issue for traveling screens; shellfish are 

not impinged, but they can attach to the traveling screen surface and are not removed 

from the traveling screen by pressure wash sprays. Barrier nets have been shown to be 

helpful in this regard. 

c. Aquatic Filter Barriers 

 

66 Barrier net mesh sizes vary, depending on the configuration, level of debris loading, species to be 

protected, and other factors. 
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Aquatic Filter Barriers (AFBs) consist of water-permeable fabric panels with 

small pores (less than 20 microns). They are similar to barrier nets in that they extend 

throughout the area of water withdrawal from the bottom of the water column to the 

surface. AFBs reduce both impingement mortality and entrainment because they present 

a physical barrier to all life stages. The surface area of an AFB is quite large compared to 

a traveling screen, allowing for extremely low water velocities. The low velocity allows 

non-motile organisms to drift away. EPA is aware of one power plant that used an AFB 

but notes that this facility recently ceased operations.67 EPA has updated performance 

data for AFB for small flow intakes, but it does not have enough data to evaluate the 

technology at large intakes or in all water bodies. EPA does not consider this technology 

to be demonstrated and available as a nationwide BTA candidate.

d. Collection and Return Systems 

Conventional traveling screens were not designed initially with the intention of 

protecting fish and aquatic organisms that become impinged against them. The organisms 

were often handled in the same manner as debris on the screens. Marine life can become 

impinged against the screens because of high intake velocities that prevent their escape. 

Prolonged contact with the screens can suffocate organisms that are unable to escape or 

result in descaling injury and latent mortality. Organisms that survive initial impingement 

and removal are not always provided with a specifically designed mechanism to return 

 

67 This facility ceased operations for reasons other thanunrelated to any requirements or measures 

addressing cooling water intake impingement andor entrainment related to cooling water intake. 
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them to the water bodywaterbody and are often handled in the same way as other 

screening debris. Other objects, such as leaves and trash, that are collected on the screen 

are typically removed with a high-pressure spray and deposited in a dumpster or debris 

return trough for disposal. Exposure to high pressure sprays and other screening debris 

can cause significant injuries that result in latent mortality or increase the susceptibility to 

predation or re-impingement. Screens are rotated periodically on a set time interval or 

when the pressure differential between the upstream and downstream faces exceeds a set 

value. 

Conventional traveling screen systems have been modified to reduce 

impingement-related mortalities with collection and return systems. In its simplest form, 

these systems are composed of a return flume or trough with sufficient water volume and 

flow to enable impinged organisms to return to the source water. Return systems should 

be designed to avoid predation and latent mortality while organisms are in the flume, 

maintain an appropriate water depth in the flume for high survival of the organisms, 

located at an appropriate elevation to avoid large drops of the organisms back to the 

surface water (or large hydraulic jumps if the end of the return is below the water’s 

surface), and sited to avoid repeated impingement of the organisms by the intake 

structure. 

Some facilities have modified conventional coarse mesh traveling screen systems 

to reduce impingement mortality. They did this by removing fish trapped against the 

screen and returning them to the receiving water with as few injuries as possible. The first 

modified screens, also known as Ristroph screens, feature capture and release 
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modifications. In the simplest sense, these screens are fitted with troughs (also referred to 

as buckets) containing water that catch the organisms as the screen rises out of the water 

and the organisms are sprayed off of the screen. The return component consists of a 

mechanism to remove impinged fish gently from the collection buckets, such as a lowpressure spray. The buckets empty into a collection trough that returns fish to a suitable 

area in the source water bodywaterbody. These modified screens have shown significant 

reductions in impingement mortality compared with unmodified screen systems. 

Data from early applications of the Ristroph screen design showed that while 

initial survival rates might be high at some installations, latent mortality rates were higher 

than anticipated. This indicated that organisms could sustain significant injuries during 

the impingement and return process that were not immediately fatal. According to a study 

conducted by Ian Fletcher in the 1990s (see DCN 5-4387), industry identified several 

additional critical screen modifications to address latent mortality. These included 

redesigning the collection buckets to minimize turbulence, adding a fish guard rail/barrier 

to prevent fish from escaping the collection bucket, replacing screen panel materials with 

“fish-friendly,” smooth woven mesh, and using a low-pressure wash to remove fish 

before any high-pressure spray to remove debris. The Fletcher analysis also identified 

longer impingement duration, insufficient water retention in the buckets, and exposure to 

the air and temperature extremes as conditions that could negatively affect fish survival. 

Finally, these findings indicate that modified Ristroph screens must be rotated continually 

instead of the periodic rotation schedule common with conventional screen systems. 

Performance data for modified traveling screens with fish-friendly fish return systems, 
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sometimes referred to as post-Fletcher modifications, show low levels of impingement 

mortality across a wide variety of water body types and fish species. Therefore, EPA has 

concluded that modified traveling screens with a fish-friendly fish return system is a best 

technology available for impingement mortality. 

waterbody types and fish species. Additionally, recently developed screen designs 

(such as the Passavant Geiger, Beaudrey WIP, and Hydrolox screens) have also shown 

promise in reducing impingement mortality. 

For additional and more detailed discussion of the specific design and operation 

of these screen modifications, see Chapter 6 of the TDD. 

3. Other Technological Approaches 

a. Intake Location and Velocity Caps 

The most common intake location for a cooling water intake structure is along a 

shoreline. In some water bodies, however, shoreline locations are thought to have a 

potential for greater environmental impact because the water is withdrawn from the most 

biologically productive waters, especially those containing a high density of organisms in 

earlier life stages, such as nursery areas. Some facilities employ an offshore intake to 

withdraw water from less biologically productive areas to reduce impingement and 

entrainment relative to intakes in more productive shoreline areas. Reduction in 

impingement mortality and entrainment due to intake location is highly site-specific. The 

greatest potential for reductions is found with far offshore locations at distances of 

several hundred feet, not found on many rivers and streams. Both depth and the offshore 

location must be evaluated to determine whether fish densities and species distribution 
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there are substantially different than those near the shoreline. Two areas where far 

offshore locations are commonly used today are the oceans and Great Lakes. 

EPA found that several offshore intakes are fitted with a velocity cap.68 Velocity 

caps are a physical structure rising vertically from the sea bottom and are placed over the 

top of an intake pipe. Intake water is withdrawn through openings in the velocity cap so 

that it converts the direction of water flow into the pipe from vertical to horizontal. The 

velocity cap does not act to reduce the velocity,69 but the horizontal flow provides a 

physiological trigger in fish, which induces an avoidance response to reduce 

impingement mortality. The velocity cap further serves to limit the zone of influence of 

the intake to the depth level at which the velocity cap is situated, thus affecting only the 

life stages that live at that depth. Velocity caps are also usually equipped with supports 

and bar spacing selected to prevent larger aquatic organisms (e.g., sea turtles or marine 

mammals) from entering the intake pipe. Because velocity caps operate under the 

principle that the organisms can escape the current, they do not offer entrainment 

reductions over and above those achieved by being located offshore. Reductions in 

entrainment observed with velocity caps occur because of the difference in organism 

densities in far offshore deep water compared to a surface intake at the shoreline. 

 

68 Others can be fitted with a cylindrical wedgewire screen, or might simply be an open pipe. 

69 EPA’s data show that velocity caps operate at velocities above and below the 0.5 fps and can be effective 

using either design. 
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Far offshore velocity caps have limited application in oceans and the Great Lakes, 

are not available in other water bodies, and are therefore not available as a candidate for a 

national BTA. However, the technology is a demonstrated high performing technology, 

and is therefore included as a compliance alternative for those facilities where the 

technology is available. For additional and more detailed discussion of the specific 

design and operation of offshore intake locations and velocity caps, see Chapter 6 of the 

TDD. 

b. Reduced Intake Velocity 

Impingement mortality can be reduced greatly by reducing the through-screen 

velocity in any screen.70 Reducing the rate of flow of cooling water through the screen 

(through-screen velocity) to 0.5 fps or less reduces impingement of most fish because it 

allows them to escape the intake current. (See 66 FR 65274 [December 18, 2001] and 

DCN 2-028A, EPRI’s “Technical Evaluation of the Utility of Intake Approach Velocity 

as an Indicator of Potential Adverse Environmental Impact Under Clean Water Act 

316(b).”) As a result, some facilities have designed and operate their modified traveling 

screens or wedgewire screens so as not to exceed a through-screen velocity of 0.5 fps. 

Swim speed studies demonstrate that for most facilities, an intake velocity of 0.5 fps or 

 

70 Limited lab studies indicate that entrainment also can decrease as through-screen velocity decreases and 

that through-screen velocity can have an effect on entrainment survival rates, although such data is 

extremely variable by species (see DCN 10-6802 and DCN10DCN 10-6803). In any case, EPA does not 

consider a reduced intake velocity as an effective technology for reducing entrainment, because entrainable 

organisms generally lack motility. 
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less will result in 96 percent or better reductions in impingement mortality for most 

species. EPA notes that preliminary results from recent studies of fine mesh screens 

suggest that at even lower intake velocities such as 0.25 fps, some hydrodynamic 

influences may reduce entrainment mortality even more, because flow dynamics are 

nonlinear. It is unclear as to whether such observations hold true when cooling water 

withdrawals (water volumes) are large. Therefore, EPA has concluded that reduced 

intake velocity is a best performing technology for impingement mortality.While higher 

intake velocities are sufficiently protective for some species of fish, the higher intake 

velocities are not necessarily protective of all life-stages. For example, younger fish may 

not be strong swimmers or may have not a developed avoidance response. Therefore 

higher intake velocities are not a high performing technology. As noted previously, low 

intake velocity has limited application, and is therefore not available as a candidate BTA 

technology. However, the technology is a demonstrated high performing technology, and 

is therefore included as a compliance alternative for those facilities where the technology 

is available. 

CD. Technology Basis for Today’s Final Rule 

As described above, EPA examined the full range of technologies that reduce 

impingement or entrainment or both, and evaluated these technologies on the basis of 

their efficacy in reducing impingement and entrainment, and their availability, which 

includes feasibility and cost.. From an assessment of theseall factors, EPA identified 

twoone technology that is best performing technologies as the basis for today’s final 

ruletechnology available for minimizing the adverse impacts of impingement mortality at 
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existing facilities: modified traveling screens with a fish-friendly fish return. EPA 

identified no single best technology that is available for impingementminimizing 

entrainment at existing facilities andfor today’s final rule. For new units at existing 

facilities, EPA identified mechanical draft wet cooling systemsystems as BTA for both

impingement and entrainment at new units.

71 

EPA did not identify any single technology or group of technology controls that it 

concluded were available and feasible as the basis for establishing the national 

performanceBTA standard for entrainment. for existing units. Instead, EPA’s EPA has 

established a national BTA entrainment standard puts in place a framework for 

establishingfor entrainment for existing units that requires determination of BTA

entrainment requirements on a site-specific basis. in a structured permitting setting. The 

framework includes thefor determining entrainment requirements provides for the 

consideration at a minimum of certain specified factors that must be considered in the 

Director’s determination of the appropriate BTA controls as well as the standard for 

determining when an otherwise affordable control technology may be rejected as the 

basis for the BTA standard. As described below, other technologies are demonstrated, but 

they are neither the best performing nor available technologies for the industry as a 

whole.. 

 

71 Although EPA also identified velocity reduction to 0.5 feet per second or less as a candidate best 

performing technology for impingement mortality, EPA did not promulgate requirements to reduce intake 

velocity as BTA because it is not available at all facilities; however, the final rule does allow facilities to 

comply with intake velocity of 0.5 feet per second or less where available. 
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1. 1. Alternative Impingement Mortality Standards for Existing FacilitiesUnits

After considering all factors identified above, EPA has concluded that modified 

traveling screens, such as modified Ristroph screens and equivalent modified traveling 

screens with fish-friendly fish returns, are a best performing technology available for

minimizing impingement mortality.72 These screens use 3/8 inch, or similar, mesh with 

collection buckets designed to minimize turbulence, a fish guard rail/barrier to prevent 

fish from escaping the collection bucket; “fish-friendly,” smooth, woven or synthetic 

mesh; and a low-pressure wash to remove fish before any high-pressure spray to remove 

debris. The fish removal spray must be of lower pressure, and the fish return must be fish 

friendly, provide sufficient water and minimize turbulence. Modified traveling screens 

generally must be rotated continually to minimize aquatic exposure to impingement or to 

the air and thus obtain the highest reductions in impingement mortality. 

Under the seventh compliance option for complying with the BTA impingement 

mortality standard in today’s final rule, a facility may chooserely on any technology and 

then must conductit chooses so long as it demonstrates through biological compliance 

monitoring to demonstrate the annual average limit is achieved.that it achieves the 

required 12 month impingement mortality performance standard73 that EPA calculated 

 

72 EPA also considered recent screen designs (such as the Passavant Geiger, Beaudrey WIP, and Hydrolox 

screens) in evaluating impingement mortality data. In fact, the data set used to calculate the revised 

impingement mortality limitperformance standard at § 125.94(c)(7) included a study of performance at a 

facility employing a Passavant Geiger screen, as well as a facility employing a Beaudrey WIP screen. 

73 In the record, EPA may also refer to this as the 12-month percent survival performance standard, % SPS, 

or the IM performance standard. 
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based on the performance of the BTA technology – modified traveling screens with fish 

return. As discussed in the TDD (see, for example, TDD Exhibits 11-1 and 11-3), EPA 

based the annual average limit12 month percent mortality performance at § 125.94(c)(7) 

on data from facilities with traveling screens modified with features to improve the postimpingement survival of organisms such as smooth mesh, continuous or near-continuous 

rotation of the screens, buckets with guard rails, low pressure sprays for collecting fish, 

and fish return systems. The statistical basis for the annual limit includes 26 annual 

averages12 month impingement mortality performance standard includes 26 sets of 12 

month survival percentages across 17 facilities demonstrating average impingement 

mortality rates ranging from 1.6 to 48.8 percent under conditions of 18 to 96 hour holding 

times.74 EPA established the annual average limitation12 month percent mortality as 

2524 percent which is the arithmetic average of the impingement mortality rates from the 

17 facilities. (This is consistent with EPA’s proposed rule use of expected value of the 

beta distribution which can be calculated as the arithmetic average.) Note: The 12 month 

impingement mortality performance standard means that no more than 24 percent of the 

impinged fish may die or alternatively at least 76 percent of the impinged fish must 

survive. EPA has occasionally used average annual limitations in the effluent guidelines 

 

74 In the Roseton study, one of the dual flow screens (Screen 2D) that was tested in 1990 failed due to a 

high water level differential. The replacement screen was another modified dual flow screen with the same 

orientation, but with unspecified modifications. A 1994 study showed these modifications resulted in 

reduced impingement impacts via reduction in the number of fish impinged and better survival of impinged 

organisms. EPA did not exclude the 1990 study from the annual average limit calculation because the study 

met all specific criteria. See TDD Chapter 11 for further information.
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program, most recently for the pulp and paper industry category (40 CFR 430, 

promulgated in 1998). In suchthese instances, such as the technology-based BAT, EPA 

has defined the annual average limitations to be the average level demonstrated by the 

technology. Thus, EPA’s approach to calculating the annual12 month percent survival 

performance standard for impingement mortality is consistent with past practice. 

EPA recognizes that variability in the technology performance occurs due to 

changes in seasons, differing intake locations, higher mortality of certain species, and 

speciation found in different water bodies. By using a full 12 months of data, EPA has 

ensured that the resulting performance standard reflects the widest range of potential 

conditions present in EPA’s database. EPA has further incorporated variability into the 

annual average limitation12 month impingement mortality performance standard by 

basing its limitationit on data from 17 facilities which collectively performed more than 

1,500 sampling events beginning as early as 1977. EPA notes that seven facilities had 

mortality rates less than 10 percent which provides evidence that facilities can, and have, 

maintained and operated their systems in a manner consistent with the limit.performance 

standard. Another four facilities demonstrated impingement mortality rates significantly 

greater than the limitperformance standard of 2524 percent, however, EPA notes these 

facilities were not required to optimize their technology performance as part of their 
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study, and data collection was not required to achieve a certain level of performance.75 In 

each study, EPA has identified elements of the technology operation that a facility could 

modify to achieve the annual average limitation.12 month percent impingement mortality 

performance standard. By using the average annual12 month percent impingement 

mortality performance standard, EPA has ensured that the resulting 

limitationperformance standard reflects the widest range of potential conditions present in 

EPA’s database. In addition to those studies meeting the criteria for use in the annual 

average limitation12 month percent survival performance standard calculations, there are 

further studies in EPA’s record that provide additional performance data showing 

facilities can, and have, maintained and operated their systems in a manner consistent 

with the limit.performance standard. EPA’s record includes approximately 250 total 

studies related to impingement (see TDD Exhibit 11A-1). 

EPA recognizes that variability occurs due to changes in seasons, differing intake 

locations, higher mortality of certain species, and speciation found in different water 

bodies. EPA has incorporated variability into the annual average limitation by basing its 

limitation on data from 17 facilities which collectively performed more than 1,500 

sampling events beginning as early as 1977. By using the average annual performance, 

 

75 For example, the Indian Point study states “Because of the preliminary nature of this study, the 

effectiveness of the continuously operating fine mesh traveling screen has not been fully evaluated. Further 

studies incorporating controls for survival testing, regulation of spray wash pressures, collection efficiency 

tests, sampling during peak impingement periods for all important species, and better holding facilities, will 

provide more conclusive results.” 
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EPA has ensured that the resulting limitation reflects the widest range of potential 

conditions present in EPA’s database. EPA notes that four facilities demonstrated 

impingement mortality rates of less than 10 percent which is well below the limit of 25 

percent. Another seven facilities had rates between 10 and 25 percent which provides 

additional evidence that facilities can, and have, maintained and operated their systems in 

a manner consistent with the limit. 

Despite the overwhelming evidence that the annual average limit of 2512 month 

percent survival performance standard of 24 percent was consistent with demonstrated 

performance for the best technology, EPA considered other alternatives that might 

incorporate more variability into a limit.performance standard. EPA concluded that none 

of the alternatives were consistent with the need for facilities to demonstrate ongoing 

maintenance and operations over a long period of time, such as a year. Any alternative 

would be less stringent and would allow facilities to target long-term performance at a 

level that would be less than the optimal performance demonstrated by facilities with the 

technology in place. However, as part of this evaluation, EPA determined that the annual 

average limit would beFurther, the 12-month average impingement mortality 

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 counterbalance a result above the standard by one below the standard. If EPA had 

included a monthly average 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 determined that the 12 
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month impingement mortality performance standard is sufficient to ensure performance 

consistent with best technology available. For this reason, EPA is not promulgating the 

monthly average limit that was included in the proposal. EPA’s decision also is consistent 

with effluent guidelines where compliance with the monthly average limitation is not 

required for facilities subject to a longer term limitations such as an annual average 

limitation (e.g., pulp and paper 40 CFR 430 Subpart B AOX limitation). 

EPA also dropped several proposed did not include in the final rule a number of 

requirements. it had considered at proposal. The proposed rule would have required the 

seasonal deployment of barrier nets on estuaries and oceans as one element of the best 

performing technology available for minimizing the impingement mortality of shellfish 

(crustaceans). EPA has opted not to include any specific requirements for shellfish in the 

final rule, because EPA’s review of the impingement data it used to develop the today’s 

final rule impingement performance standard showed that ampleincludes data were 

available to that incorporate shellfish survival as part of the impingementperformance

standard. Further, as previously explained, the final rule provides for the Director to 

establish additional requirements where necessary. 

EPA expects facilities complying with § 125.94(c) of today’s rule by compliance 

option (7) to track their compliance with the annual average12 month percent 

impingement mortality performance standard on an ongoing basis and to proactively 

modify their technology or operations when a trend in the sampling suggests that they 

might be in danger of exceeding the annual average12 month percent impingement 

mortality performance standard in the future. The annual average12 month percent 
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impingement mortality performance standard requires that impingement mortality not 

exceed 2524 percent, calculated as the sum total number of fish that were impinged and 

died within the holding time divided by the sum total number of fish impinged for a 12-

month period. EPA expects the ratio will be calculated based either on direct sampling 

counts, or based on both counts being extrapolated to represent annual counts. Because 

comments provided data that expanding the proposed 24 to 48 hour holding time 

requirement would generally not affect the observation of mortality due to impingement, 

the regulation allows for holding times from 18 to 96 hours. 

As explained in more detail in sectionSection VI.E and G below, the BTA 

technology for impingement does not minimize adverse environmental impacts 

associated with entrainment. 

2. Entrainment Standards for Existing Units 

As discussed below, EPA is not basing BTA for entrainment at existing units (that 

is, excluding new units at existing facilities) on a single technology such as closed-cycle 

recirculating cooling systems, the best performinga highly effective technology, because 

this technology is not available nationally. Although EPA’s record shows numerous 

instances of existing units that have performed a retrofit to closed-cycle, EPA has and 

therefore does not identified it asrepresent BTA. EPA also has not identified any other 

effective, available and demonstrated candidate technology (or combinations of 

technologies) for entrainment reduction at existing units that is available nationally. For 

other entrainment technologies that might be available on a site-specific basis, see 

sectionSection VI.E.2 below and chapterChapter 6 of the TDD. EPA did not select the 
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other flow-reduction technologies (such as variable-speed drives and seasonal flow 

reductions) as the technology basis for entrainment control measures because these 

technologies are not uniformly best and are not broadly available for most facilities. 

Further, EPA has not identified a basis for subcategorizing existing units at which flow 

reduction technologies are feasible. The effectiveness, availability, and utility to a given 

facility of flow reduction or other entrainment reduction methods depends on site-specific 

geographical and biological conditions as well as operations of the facility. For example, 

this is the reason that EPA did not select relocation of a shoreline intake to far offshore as 

a technology basis for the BTA entrainment standard because this technology is not 

widely available for most facilities. 

3. Impingement and Entrainment Standards for New Units at Existing Facilities 

In contrast to existing units, installing a closed-cycle cooling system at a new unit 

is far less complex. The technology is also highly effective, as generally achieving 

greater than 95 percent reductions in IM and E (mechanical draft (wet) cooling towers 

achieve flow reductions of 97.5 percent for freshwater and 94.9 percent for saltwater 

sources, or by operating the towers at a minimum of 3.0 and 1.5 COCcycles-ofconcentration, respectively.). These reductions in flow (and the concurrent reductions in 
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impingement and entrainment impacts) are among the highest reductions in adverse 

environmental impact possible at an intake structure.76

As described below, EPA has concluded that new units, in contrast to existing 

units, have much greater flexibility in terms of cooling system design, construction 

scheduling, and other factors that help minimize many of the negative aspects associated 

with closed-cycle cooling. For a more detailed discussion of this rationale, see below. 

On the basis of the high levels (greater than 95 percent on average) of flow 

reduction obtained by optimizedUnder the final rule, a new unit at an existing facility, 

where the facility that withdraws or will withdraw more than 2 mgd when the new unit 

begins operating will have requirements similar to the requirements of a new facility in 

Phase I. Under the rule, a new unit (as defined at § 125.92(u) and described above) is 

required to have a flow limited to that which is commensurate with a closed-cycle 

recirculating system as it would be applied to the new unit. Today’s final rule also 

includes an alternative approach (similar to Track II in Phase I), in which a facility could 

comply with the new unit standards by demonstrating that the technologies and 

operational measures employed will reduce the level of adverse environmental impact 

from any cooling water intake structure used to supply cooling water to the new unit to a 

 

76 Note that these metrics are not explicit requirements for closed-cycle recirculating systems. They simply 

represent what EPA views as examples of characteristics of a properly operated and maintained closedcycle coolingrecirculating system., as defined at § 125.92(c)(1).
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comparable level to that achievable by implementing a closed-cycle recirculating system 

as defined at § 125.92(c)(1). 

As discussed above, today’s final rule defines a “new unit” at an existing facility 

as a stand-alone unit the construction of which commences after the effective date of 

today’s final rule. New unit includes stand-alone units that are added to a facility for 

purposes of the same general industrial operation as the existing facility. This is in 

contrast to the definition of new facility, where a new facility does not include new units 

that are added to a facility for purposes of the same general industrial activity (40 CFR 

125.83). The provision “for purposes of the same general industrial operation” is 

explicitly included in today’s final rule definition of new unit at an existing facility for 

clarity. A new unit may have its own dedicated cooling water intake structure, or the new 

unit may use an existing or modified cooling water intake structure. Any unit at an 

existing facility that does not meet the new unit definition in today’s rule is subject to the 

existing unit provisions. 

EPA is adopting more stringent requirements for new units at existing facilities 

because such new units can be designed and constructed without many of the additional 

expenses and operational disadvantages associated with retrofitting an existing unit to 

closed-cycle cooling. For example, the incremental downtime that can be associated with 

retrofitting to closed-cycle cooling is avoided altogether at a new unit. In addition, when 

new units are added, the condensers can be configured for closed-cycle, reducing energy 

requirements (by substantially reducing the turbine backpressure energy penalty) and 

associated air emissions. 
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The three factors that led EPA to reject closed-cycle cooling as BTA (described 

below in Section E) are far less relevant for new units at existing facilities than for 

retrofitting existing units. This section discusses why EPA concluded that each factor is 

not a significant concern for new units, and why the record supports EPA’s conclusion 

that closed-cycle cooling is an available and feasible technology for new units at existing 

facilities.

 Land Availability: In contrast to retrofitting the entire existing facility, the amount 

of space dedicated to closed-cycle for the new unit will be limited to the new unit 

rather than the entire facility. As a result, space constraints will be much less of an 

issue. New units also present the opportunity to design an optimized closed-cycle 

recirculating system for the new unit. Retrofitting an existing facility for the full 

intake flow of the facility would require a facility to identify (or possibly obtain) 

enough space to accommodate the cooling towers and associated equipment. 

Furthermore, new units and their corresponding cooling system can be built in 

stages rather than as a facility-wide retrofit, and since the new unit has not yet 

been built, there is no energy reliability concern (discussed further below). 

 Air Emissions: EPA expects that emissions are significantly less of a concern at 

new units. The condensers will be optimized for closed-cycle, 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. Turbine backpressure and the associated energy penalty can be 

substantially reduced in a new unit, but EPA acknowledges new units will still 
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have auxiliary power consumption for fans. Therefore energy penalties and air 

emissions for tower operations can be minimized (though not eliminated). The 

emissions effects of requiring closed-cycle cooling at new units at existing 

facilities is similar to the effects of this requirement at new facilities and will not 

pose an unacceptable impact. For more information, see 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. 

 Remaining Useful Plant Life: This is clearly not an issue for new units. A new 

unit has its full useful life remaining and thus would experience the maximum 

possible reductions in adverse environmental impacts throughout that useful life. 

 EPA does not expect that the requirements for new units at existing facilities will 

be a disincentive for facilities to repower existing units. The requirements only apply to 

stand-alone units. Requirements for entrainment at repowered units will thus be 

determined by the Director. EPA notes, however, for facilities that do choose to repower 

an existing unit, the costs of employing a closed-cycle cooling system are not a barrier, as 

described above. In fact, some facilities may find closed-cycle cooling to be less costly 

over the long-term. For example, in locations with limited water resources such that 

once-through cooling of an additional unit is not possible, overall reliability will be 

increased by using closed-cycle cooling systems. 
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 EPA also recognizes that installing closed-cycle cooling systems at new units is a 

prevailing trend in industry, regardless of the regulatory requirements imposed by today’s 

final rule. For example, see DCN 12-6672 in the record for today’s rule, and DCNs 2-009 

and 4-4023C (from the Phase I and Phase II dockets, respectively). These documents 

show that, on the basis of responses from facilities to the 316(b) industry questionnaire, 

facilities constructed in recent years are significantly more likely to employ closed-cycle 

cooling.

EPA recognizes that at some point in the future, every unit will be rebuilt, 

replaced or repowered (or retired). EPA projects that approximately 227 MW in new 

generating capacity per year, will be subject to the new unit provision, reflecting the 

general industry trend towards more efficient units. EPA’s analysis projects an equivalent 

number of new units at manufacturing facilities will be constructed each year. See the 

Phase I rule for more information regarding the affordability and barrier to entry analysis 

for new construction. 

EPA notes that the new unit provision is an important element of the final rule, 

given the generally long lifespan of equipment at industrial facilities. For example, 

generating units at a power plant are often projected to have a 50-year lifespan. As a 

result, these facilities have a slow rate of “evolution” in adopting newer technologies. By 

requiring closed-cycle cooling in new units, EPA is ensuring (along with the Phase I rule) 

that no new once-through cooling units or facilities will be built. 
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E. Option Selection 

After considering all factors identified above, EPA has concluded that it should 

base the BTA impingement mortality standard for existing units on the performance of 

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. While there are a number of technologies that may perform as 

well as or better than traveling screens, 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 traveling screens because EPA concluded that this 

technology is effective, widely available, feasible,77 and does not lead to unacceptable 

non-water quality impacts. 

As explained above, 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 

 

77 As part of the feasibility determination, EPA found that the costs associated with the IM standards are 

reasonable for the industry as a whole. 
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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 closed-cycle recirculating systems reduce entrainment 

(and impingement mortality) to the greatest extent and are the most effective performing 

technology, after careful consideration of multiple factors, EPA concluded that a closedcycle recirculating system 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 reasons explained below. 

EPA also determined that there were no other “available” technologies for 

entrainment whose performance came close to that of closed-cycle recirculating systems. 

Further, while reduced intake velocity was a very effective control for impingement 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, and it is not 

physically available in many locations. 

EPA has broad discretion in what factors it should consider when it determines 

the best technology available for minimizing the adverse environmental impacts of 

cooling water intake structures. As both the U.S. Supreme Court and the Second Circuit 

Court of Appeals have underscored, section 316(b) is “sui generis,” in a class by itself, 

unencumbered by “specified statutory factors,” Entergy Corp. v. Riverkeeper, Inc, 556 

U.S. 208, 222 (2009); Riverkeeper, Inc. v. EPA, 358 F, 3d 174,187 (2d Cir. 2004). The 

Second Circuit explicitly rejected the argument that, because section 316(b) does not 
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mention costs or other factors, EPA cannot give costs or other factors “any” weight in 

deciding what is the best technology. Riverkeeper, Inc., 358 F.3d at 195. Furthermore, 

the Second Circuit recognized that EPA may base its decision on factors other than the 

effectiveness of a given technology in reducing impingement and entrainment and that 

EPA is entitled to deference in deciding what weight to give to the factors it considers in 

its BTA determination. Riverkeeper, Inc., 358 F.3d at 196. 

As noted, costs are one factor EPA may consider in its BTA determination. Here, 

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 entrainment standard. EPA 

did not reject closed-cycle cooling here either because it was not economically achievable 

or because the costs of closed-cycle would exceed its benefits. Instead, 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 as explained below. 

Central to EPA’s evaluation of the availability of closed-cycle as BTA was EPA’s 

new understanding of the limitations of technologies other than closed-cycle in reducing 

entrainment. This presented EPA with a sharper choice than it had in the Phase II rule. 

For today’s rulemaking, EPA took a second look at the data it had relied on in the Phase 

II rule, particularly in light of new data received since the Phase II rule. As a result, EPA 

learned that entrainment exclusion does not necessarily equate to entrainment survival 

(76 FR 22185), a key underpinning to EPA’s BTA standards for entrainment in the 

remanded Phase II rule. 
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For the remanded Phase II rule, EPA had established national BTA performance 

standards for entrainment (and impingement) and included a number of different 

alternative means to achieve the standards. First, if a facility demonstrated that it could 

achieve reductions in flow associated with closed-cycle cooling, the facility met the BTA 

performance standards. Alternatively, a facility could demonstrate that it met the 

entrainment performance standards by a combination of installed technology and 

operational or other measures (including restoration measures). See 69 FR 41590 for a 

description of the final Phase II rule. Critical to EPA’s decision to provide an array of 

choices for achieving the national BTA entrainment performance standards was a key 

factual conclusion. That conclusion was that a number of technologies would achieve 

performance reducing entrainment that was “comparable” to that of closed-cycle cooling. 

Consequently, for the Phase II rule, EPA established an entrainment performance 

standard of 60 to 90 percent based on data it reviewed for the Phase II rulemaking. See 

69 FR 41598 for information on EPA’s rationale for establishing compliance alternatives 

as part of the final rule. 

In the Phase II rule, while EPA looked to the performance of closed-cycle as the 

benchmark against which it evaluated technologies for the BTA standards, EPA did not 

mandate the achievement of flow reductions that were in all cases equivalent to closedcycle. Given that the available data supported the view that there were other much less 

expensive technologies that obtained significant reductions in entrainment, EPA was 

comfortable with a BTA standard that required achievement of a level of performance 

that was generally comparable though not equivalent to closed-cycle. 
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Since the Phase II rulemaking, EPA has received new data and learned that its 

understanding of entrainment technology performance was incomplete. Following the 

remand of the Phase II rule, EPA reexamined the data as well as new information on the 

performance of various entrainment control technologies it had previously reviewed. As 

a result, EPA determined that its conclusion regarding the capability of these other 

technologies – a conclusion on which the Agency had based the Phase II BTA 

performance standards – was no longer supported by the data EPA had before it. 

There is a second additional consideration that further required EPA to focus 

renewed attention on how widely available closed-cycle cooling in fact was nationally. 

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 closed-cycle 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 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 
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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. Riverkeeper, Inc., 358 F.3d at 196. EPA identified three factors as 

significant in its decision to reject closed-cycle cooling as the sole technology basis for a 

national BTA entrainment standard. The 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. 

1. Land Availability and Geographical Constraints Could Be a Factor on a Local 

Basis 

While EPA’s record indicated that the majority of facilities have adequate 

available land to retrofit to closed-cycle cooling, some facilities have land constraints.78

While EPA originally estimated as many as 23 percent of facilities would not have 

enough space,79 it observed on site visits that 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 with large acreage could not feasibly install 

 

78 For example, in the case of fossil fuel facilities, scrubber controls may already have been required to 

comply with air rules and standards. This may reduce available land for closed-cycle. 

79 EPRI reported at least 6 percent of sites it evaluated were deemed “infeasible” because no space was 

available on which to locate a cooling tower. (DCN 10-6951) While EPA does not have access to the 

facility level data, EPRI’s report supports EPA’s conclusion that there is significant uncertainty around 

space constraints for facilities to install closed-cycle cooling. 
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cooling towers because of local zoning or other local concerns. Thus, existing physical 

space at the facility was not the only factor contributing to uncertainty about land 

availability. 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, and the cost of acquiring new land may be 

prohibitive for some facilities. Consequently, EPA estimates that 25 percent or more of 

facilities might have one or more constraints on land availability that would limit the 

ability to retrofit for cooling towers for the entire facility. EPA lacks adequate support to 

indicate that land constraints can be accommodated at existing facilities. 

EPA also 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. For example, 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. 

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

As previously discussed, 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 
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others.80 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 (2) slightly lower generating efficiency attributed to higher 

turbine backpressure when the condenser is not replaced with one optimized for closedcycle operation when retrofitting existing units (also referred to as the energy penalty). 

While both of these factors contribute to increased air emissions, the larger contributor to 

projected increased air emissions is by far 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 

directly with an increase in human health effects. EPA notes that cooling plume 

abatement and drift elimination technologies exist to address cooling tower emissions 

(and EPA included costs for such technologies in its analysis of Proposal Options 2 and 

3). 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 is increased air emissions associated 

 

80 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. 
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with additional fuel usage due to the 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 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.

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

A number of facilities are nearing the end of their useful life. Considering the 

long lead time to plan, design, and construct closed-cycle cooling systems, EPA 

determined that the Director should have the latitude to consider the remaining useful 

plant life in establishing entrainment mortality 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 closed-cycle 

system at a facility that is scheduled to close in three years will result in little entrainment 

reduction as compared to retrofitting to closed-cycle at a facility that will continue to 

operate for a significantly longer period. 

The Decision to Establish a National BTA Standard Requiring Site-Specific 

Determination of BTA Entrainment Controls 

Once EPA determined that a “one-size-fits-all” approach for entrainment for 

existing units is not generally feasible, it is appropriate to assess the required controls on 

a site-specific basis. Therefore, for existing units, EPA decided to adopt as the BTA 
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entrainment standard an overarching regulatory framework under which the Director will 

establish BTA entrainment requirements on a site-specific basis following prescribed 

procedures and applying specified factors for decision-making prescribed in the 

regulation and as described below. 

EPA concluded that site-specific proceedings are the appropriate forum for 

weighing all relevant considerations in establishing BTA entrainment requirements. 

Closed-cycle cooling is indisputably the most effective technology at reducing 

entrainment. Closed-cycle reduces flows by 95 percent and entrainment is similarly 

highly reduced. But given that EPA estimates that 25 percent of existing facilities may 

face some geographical constraints on retrofitting closed-cycle cooling and concerns 

about air emissions and the remaining useful life of a facility, EPA rejected the option of 

requiring uniform entrainment controls based on closed-cycle cooling. Instead, EPA 

elected to adopt as the entrainment standard a more flexible process in which, following 

consideration of a host of factors, the Director will prescribe 316(b) entrainment 

conditions appropriate at a particular site. For additional discussion on how a site-specific 

consideration of entrainment control requirements will be implemented, see Section VIII 

below. 

EPA has several reasons for adopting the framework approach as the BTA 

standard for entrainment. As explained, the record shows that though closed-cycle 

cooling is effective, it is neither widely available nor feasible, and has significant 

unacceptable non-water quality impacts. While EPA cannot identify with precision the 

extent of these limitations on installing closed-cycle cooling systems nationwide, the 
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record indicates that the circumstances are neither isolated nor insignificant. In light of 

this, EPA decided not to establish closed-cycle cooling as a presumptive BTA 

entrainment standard, pending a site-specific demonstration of the limitations. Instead, 

entrainment control requirements will be determined in a site-specific setting where the 

opportunity for local input in decision-making process will be maximized.

With regard to new units at existing facilities, based on the performance of 

properly operated cooling tower operation and the availability, feasibility and 

affordability of closed-cycle cooling at new units, EPA has identified wet cooling 

systems as the best performing technology for both impingement mortality and 

entrainment for new units at existing facilities.selected closed-cycle recirculating systems 

based on wet cooling towers as BTA. For a discussion of how the three factors 

(availability, feasibility and affordability) relate to new units, see Section VI.D.3. 

Consistent with the Phase I rule for new facilities, EPA has also included a compliance 

alternative allowing a facility to show performance comparable to that of a closed-cycle 

recirculating system. The new unit provisions in today’s final rule are essentially the 

same as the requirements for new facilities under the Phase I rule. 

D 

F. Other Options Considered for Today’s Final Regulation 

EPA considered several other options for the BTA standards in developing 

today’s rule, but ultimately rejected them. This section includes a discussion of these 

options, as well as some technologies that EPA considered, but did not include as 

compliance alternatives to the impingement mortality standards. 
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1. 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, and the starting point for the description of the changes to the rule in 

Section V above. 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.1.

 Closed-Cycle Recirculating Systems as National BTA The option analyzed here, 

called Proposal Option 4, is likewise similar to the final rule, but for the impingement 

standard based on BPJ for facilities between 2 and 50 mgd. 

EPA ultimately rejected Proposal Option 4 because EPA found that the 

technologies on which the impingement mortality performance standard of today’s final 
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rule is 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 Addressthe final rule. These facilities would have no difficulty complying 

with the requirements EPA is establishing in today’s final rule. 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 today’s final rule. In addition, the 

flexibilities introduced in the June 11, 2012 NODA and included in today’s final rule 

applied 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 they provide 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 case-bycase decision making. 
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2. Proposal Option 2—Flexible Impingement and Mortality Controls Similar to 

Final Rule at All Existing Facilities that Withdraw over 2 mgd DIF; Site-specific 

Entrainment Standard for Existing Facilities with DIF at or below 125 mgd; 

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 

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. Notwithstanding that conclusion, EPA has decided not to establish a 

performance standard for impingement and entrainment based on closed-cycle 

recirculating systems for existing facilities. Furthermore, EPA found that there are no 

other effective technologies for entrainment that are available nationally. 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, despite the smaller 

number of facilities that would be subject to a requirement to retrofit. The technology 

basis for entrainment mortality controls for facilities greater than 125 mgd DIF under this 

option would have been wet cooling systems. best performing technology for reducing 

impingement mortality and entrainmentThe constraints discussed above that are 

associated with retrofitting a large portion of the universe of affected facilities, led EPA 
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to conclude that requiring closed-cycle cooling on a uniform basis scale was not 

appropriate for a national regulation. 

Notwithstanding that conclusion, EPA has decided not to establish a performance 

standard for entrainment based on EPA notes that it proposed multiple options that 

included closed-cycle recirculating systems. 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 by section 316(b). Because of a combination of concerns 

over technical feasibility and total cost/availability, air emissions, and remaining useful 

life of the facility, EPA has rejected closed-cycle recirculating systems as the basis for 

national entrainment controls. After considering all the relevant factors, EPA determined 

that it will not establish a uniform BTAimpingement and/or entrainment controls. Nor is 

EPA able to identify a subcategory for which these concerns no longer apply. 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 establish any presumptive BTA entrainment 

outcome. EPA finds the entrainment performance standard based on retrofitting closedcycle cooling for existing units. Instead, for existing units, EPA has decided to adopt as 

the BTA entrainment standard a regulatory standards framework under which the 

Director will establish BTA entrainment requirements onin today’s final rule will provide
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a site-specific basis following prescribed procedures and applying specified factors for 

decision-making, as described below. 

EPA concluded that site-specific proceedings are the appropriate forum for 

weighing all relevant considerations in establishing BTA entrainment requirements. 

Closed-cycle cooling is indisputably the most effective technology at reducing 

entrainment given the direct relation between entrainment and flow. Closed-cycle reduces 

flows by 95 percent and consequently impingement mortality and entrainment are 

similarly highly reduced. But given that EPA estimates that 25 percent of existing 

facilities may face some geographical constraints on retrofitting closed-cycle cooling and 

EPA’s decision that 316(b) requirements should reflect consideration of costs and 

benefits, EPA rejected the option of requiring uniform entrainment controls based on 

closed-cycle cooling with the opportunity for individual facilities to show why they 

should not be subject to such controls. Instead, EPA elected to adopt as the 316(b) 

performance standard aconsistent, more open-ended process in which, following 

consideration of a host of factors, the Director will prescribe 316(b) entrainment 

conditions appropriate at a particular site. For additional discussion on how a site-specific 

consideration of entrainment control requirements will be implemented, see section VIII 

below. 

EPA has several reasons for adopting a frameworkefficient, and more effective

approach as the national BTA standard for entrainment. The record shows that closedcycle cooling is not technically available in a number of circumstances either because it is 

not feasible, has significant ancillary adverse consequences, or is otherwise unwarranted 
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by site-specific circumstances such as the age of the facility. 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. In light of this, EPA decided not to establish closed-cycle cooling as the 

presumptive BTA entrainment standard. Instead, entrainment control requirements will 

be determined in a site-specific setting where the opportunity for local input in decisionmaking process will be maximized.

Three Factors Support EPA’s Decision to Establish Site-Specific BTA Entrainment 

Control Requirements for Existing Facilities 

The three factors that support determining entrainment control requirements on a 

site-specific basis (except with respect to new units) and rejecting closed-cycle cooling 

systems as BTA are land availability, increased air emissions and remaining useful life. 

Another consideration EPA evaluated is current transmission capacity. How all these 

factors support the Agency’s conclusion that site-specific, not national, entrainment 

requirements at existing facilities (except new units) is discussed in detail below. 

a. Land Availability Could Be a Factor on a Local Basis 

While EPA’s record indicated that the majority of facilities have adequate 

available land to retrofit to closed-cycle cooling,81 some facilities have feasibility 

 

81 In the case of fossil fuel plants, scrubber controls may also be newly required to comply with air rules 

and standards. 
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constraints. EPA attempted to determine a threshold of land (for example, one analysis 

explored a threshold of approximately 160 acres per GW [gigawatt]) below which a 

facility could not feasibly install cooling towers. While EPA originally estimated as many 

as 23 percent of facilities would not have enough space,82 it observed on site visits that 

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 with 

large acreage could not feasibly install cooling towers because of local zoning or other 

local concerns. 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. Consequently, EPA estimates 

that as many as 25 percent of facilities might have either one or more constraints on 

available space that would limit retrofit of cooling towers for the entire facility and the 

cost of land acquisition is prohibitive. EPA lacks adequate support to indicate that land 

constraints can be accommodated at existing facilities. 

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

As previously discussed, retrofitting closed-cycle cooling (without also 

repowering) would result in increased air emissions of various pollutants, including 

 

82 EPRI reported at least 6 percent of sites evaluated were deemed “infeasible” because no space was 

available on which to locate a cooling tower. (DCN 10-6951) While EPA does not have access to the 

facility level data, EPRI’s report supports EPA’s conclusion that there is significant uncertainty around 

space constraints for facilities to install closed-cycle cooling. 
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particulates, sulfur dioxide, nitrogen oxides, mercury, and greenhouse gases, among 

others.83 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 (2) slightly lower generating efficiency attributed to higher 

turbine backpressure when the condenser is not replaced with one optimized for closedcycle operation. In contrast to retrofits, new units would readily optimize their cooling 

water systems for cooling towers, reducing the size of the cooling towers, increasing their 

efficiency, and reducing energy requirements. 

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. In addition, these increased emissions may make it 

more difficult to obtain air permits for facilities in those localities in nonattainment for 

PM2.5 because of the need to first identify offsets to its emissions. EPA notes that plume 

abatement and drift elimination technologies exist that may be able to address these 

 

83 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 closed-cycle cooling to once-through cooling with all other technologies held constant, 

there is an energy penalty that would lead to greater air emissions. 
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emissions (and EPA has included costs for such technologies in its analysis of Proposal 

Options 2 and 3), but emissions might not be eliminated entirely. For some facilities, the 

increased air emissions (andthan standards with an inability to obtain proper operating 

permits) will remain a barrier to installing closed-cycle cooling. 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.) EPA 

recognizes that this is separate from PM emissions from the stack as a result of increased 

fuel use. In addition, plumes of water vapor from the cooling tower could cause safety 

issues because of icing of nearby roadways and visibility constraints for facilities near an 

airport. EPA’s review of emissions data from E-GRID (year 2005) suggests that impacts 

from other pollutants will be less significant, but on a localized basis, these could still be 

significant. They 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.

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

A number of facilities are nearing the end of their useful life. Considering the 

long lead time to plan, design, and construct 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 mortality requirements for a 

facility. The remaining useful plant life, along with other site-specific information, will 
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affect the evaluation of the benefits (nonmonetized and monetized), and the overall 

comparison of costs and benefits, of closed-cycle cooling at a facility. For example, 

retrofitting a closed-cycle system at a facility that is scheduled to close in three years will 

not yield near as many benefits as a facility that will continue to operate for 20 years. 

d. Other Considerations 

In addition to the three factors above, one of the benefits of site-specific BTA is 

that it provides a kind of safety net guarding against the possibility of outage related 

electricity reliability problems. When EPA analyzed the effect of this regulations on 

electricity generation and transmission adequacy (more below), it concluded that even for 

the most stringent option there would not be any significant reduction in reliability of the 

national or regional electricity supply. There may however be local areas where the 

existing transmissions system is so limited that the outages required to retrofit with a 

closed-cycle cooling system could require extensive transmissions upgrades and stress 

the system. Some have suggested that Los Angeles and Chicago might be examples. 

While EPA does not have the expertise to evaluate such claims, the approach EPA is 

taking would avoid that possibility and thus serves as a safety net. 

EPA’s analysis of closed-cycle cooling included an analysis of current 

transmission capacity at a national and regional scale. Even the analysis of the most 

stringent option (Proposal Option 3, which would have required closed-cycle cooling for 

all facilities with a DIF greater than 2 mgd) did not indicate that there would be any 

significant reduction in the reliability of the national or regional electricity supply. By 

contrast, some external studies by stakeholders suggest that the existing facility rule 
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would significantly reduce reliability of the electric grid. These studies, however, 

assumed that EPA’s rule would be based on one-size-fits-all requirements to retrofit to 

closed-cycle cooling and that compliance would be required by 2018.84 Both assumptions 

would increase the cost of compliance significantly compared with today's rule, and the 

2018 compliance assumption would dramatically increase the costs of Proposal Option 3. 

In addition, however, during certain site visits, EPA identified several urban areas 

where – even with outage coordination efforts – the existing local transmission system 

would not be able to transfer sufficient electricity to all customers during extended 

outages of facilities associated with retrofits to closed-cycle cooling and would still 

require upgrades prior to the outage. This limitation to transmission occurs even when a 

surplus of electricity can be generated in the same NERC (North American Electric 

Reliability Corporation) region. For example, EPA identified localized circumstances in 

Los Angeles and Chicago where an extended outage of one or more generating units 

could not be readily replaced by excess capacity in nearby areas given the current 

transmission capacity. As a result, EPA has taken this uncertainty about the extent and 

likelihood of current local transmission capacity into account as an important 

consideration in the decision to require site-specific development of section 316(b) 

entrainment requirements. 

 

84 See, for example, North American Electric Reliability Council’s (NERC) Potential Impacts of Future 

Environmental Regulations Extracted from the 2011 Long-Term Reliability Assessment, November 2011 

at http://www.nerc.com/files/EPA%20Section.pdf.
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2. Proposal Option 3—“off ramp.” 

3. 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 closedcycle cooling as BTA for entrainment would apply with equal force for Proposal Option 

3. As a result, EPA has concluded Proposal Option 3, similarly, is not available at the 

national level as BTA for entrainment. EPA is not reporting in this preamble or support 

documents on any updates since proposal to the analysis of this option.appropriate as 

BTA for entrainment. 

3. Proposal Option 2—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 

As described above, each of the three factors for rejecting closed-cycle cooling as 

BTA for entrainment would also apply in the case of Proposal Option 2, despite the 

smaller number of facilities that would be subject to a requirement to retrofit. As a result, 

EPA concluded that Proposal Option 2 is not available at a national scale as BTA for 

entrainment. 
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4. Proposal Option 4 Variant 

EPA also considered a variant of Proposal Option 4. As compared to Proposal 

Option 4, this variant did not include flexible alternatives for complying with the BTA 

impingement mortality standards (including pre-approved and streamlined alternatives), 

but did adopt the 50 mgd threshold to determine those facilities for which the Director 

has more discretion in determining BTA via BPJ. EPA analyzed this option to directly 

compare the effects of introducing flexible 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). Under the analysis supporting the final rule the EPA is adopting today, however, 

today’s final rule is estimated to cost $275 million annually in comparison with an 

estimated cost of $284 million annually for the Proposal Option 4 variant. Thus, EPA has 

concluded that providing flexible alternatives for compliance with the BTA IM standard 

at all facilities is both more effective at reducing costs to society and more readily 

justified as best technology available as 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). 

The technology basis for entrainment mortality controls for facilities greater than 

125 mgd DIF under this option would have been wet cooling systems. The constraints 
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discussed above that are associated with retrofitting a large portion of the universe of 

affected facilities, in addition to the total cost, led EPA to conclude that requiring closedcycle cooling on a wide scale was not appropriate for a national regulation. 

4. Proposal Option 4—Impingement Mortality Controls Similar to Final Rule at 

Existing Facilities with DIF of 50 mgd or more; BPJ Permits for Existing 

Facilities with Design Intake Flow between 2 mgd and 50 mgd; Uniform 

Impingement Mortality and Entrainment Controls for All New Units at Existing 

Facilities Similar to Final Rule 

Under Proposal Option 4, only those existing facilities with a DIF of 50 mgd or 

more would have been required to comply with uniform national impingement regulatory 

requirements as described in the final rule. Regulated facilities with a DIF of less than 50 

mgd would not have been subject to the national impingement requirements in today’s 

final rule but would have continued to have their 316(b) permit requirements established 

on a site-specific, BPJ basis. 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 ultimately rejected Proposal Option 4 because EPA found that the final rule 

is available, feasible, and demonstrated for all regulated facilities on a national basis.

Moreover, EPA’s analysis showed that the difference in the total costs for the two options 
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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 this approach. 

These facilities would have no difficulty complying with either the final rule or 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 today’ 

final rule. In addition, the flexibilities introduced in the June 11, 2012 NODA and 

included in today’s final rule are applied to all facilities, not just the smaller withdrawing 

facilities addressed by Proposal Option 4. 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. 

5. 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. 

6. Site-Specific Approach to Addressing Impingement 

Many commenters (primarily from industrialmanufacturing 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 
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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 

low-cost technologies for impingement mortality are available, feasible, and 

demonstrated, and affordable for facilities nationally, and because. Because technologies 

are available, a fully site-specific approach would place an unnecessary additional 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, (i.e., compliance alternatives), and thus directly addressing many 

of the concerns raised by these commenters. 

7. Closed-Cycle Cooling to Address Impingement Mortality 

EPA did not select flow reduction commensurate with closed-cycle cooling as the 

technology basis for impingement mortality because, despite the incremental 

improvement in reducing impingement, the cost of closed-cycle cooling is more than 10 

times that of modified traveling screens with a fish return system. As a result, modified 

traveling screens with a fish return system are more cost-effective than flow reduction 

commensurate with closed-cycle cooling at preventing impingement mortality. 
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8. 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)).69 FR 41693). EPA has adopted, in 

significant measure, commenters’ suggestion in the BTA impingement mortality standard 

in today’s rule by including several pre-approved and several streamlined compliance 

alternatives in the form of technologies that may be approved following a demonstration 

of required performance, so long as the facility shows that its alternative technology is 

operating in a manner that minimizes adverse environmental impacts. As an option for 

achieving the impingement mortality standards, a facility may install and operate 

specified impingement controls that EPA has determined will comply withwhose 

performance is comparable to or better than the numerictechnology EPA concluded was 

the “best technology available” for impingement mortality performance 

standardreductions: 

 Closed-cycle recirculating systems, defined at § 125.92(c)

 Existing offshore velocity caps, defined at § 125.92(v)

 Technologies that result in a design intake velocity less than or equal to 0.5 fps, 

including most modern cylindrical wedgewire screens 

 Technologies that result in actual intake velocity less than or equal to 0.5 fps 
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Properly operating Although this rule leaves the BTA entrainment determination to the 

Director, with the possible BTA decisions ranging from no additional controls to closedcycle recirculating systems will comply with the entrainment standard as well.plus 

additional controls as warranted, EPA expects that the Director, in the site-specific 

permitting proceeding, will determine that facilities with properly operated closed-cycle 

recirculating systems do not require additional entrainment reduction control measures.

Refer to Section E.1 for the EPA’s rationale for selecting these controls. 

9. Barrier Nets 

For estuaries and oceans, EPA proposed seasonal deployment of barrier nets on 

marine waters to address impingement mortality of shellfish (crustaceans). Following 

EPA’s analysis of additional data described in the June 11, 2012 NODA, EPA has 

incorporated data regarding shellfish impingement survival rates into the numeric 

impingement mortality performance standard in the final rule, thereby eliminating the 

need to require barrier nets. However, EPA does recognize that barrier nets may be an 

appropriate measure for the protection of shellfish at some facilities and therefore has 

included a provision that gives the director discretion to require additional measure for 

the protection of shellfish. 

10. Cylindrical Wedgewire Screens 

EPA did not select wedgewire screens as the technology basis for impingement 

mortality controls because wedgewire screens are not available and feasible for all 

existing facilities. EPA also did not need to include wedgewire screens as a pre-approved 

compliance alternative for impingement controls because wedgewire screens are typically 
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designed with an intake velocity of 0.5 fps and therefore, can demonstrate compliance 

with the impingement mortality standard under the intake velocity compliance 

alternative. 

E. Option Selection 

In the proposed rule, EPA discussed four primary options. EPA also described 

additional options being considered for impingement mortality controls to provide 

facilities greater flexibility in achieving a BTA impingement mortality standard in 

its June 11, 2012 NODA (77 FR 34317). After a careful review of these 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, but a modification of, Proposal Option 1. G. Final Rule BTA 

Performance Standards 

The rule establishes the following BTA standards for Impingement Mortality and 

Entrainment: Uniform Impingement Mortality ControlsStandards at All Existing Units at 

Existing Facilities that withdraw overgreater than 2 mgd DIF; an Entrainment Standard 

based on Site-Specific Entrainment Controls that requires site-specific entrainment 

controls determined by the EPA or the State NPDES permitting authorityDirector for 

Existing Units at Existing Facilities (other than New Units) that withdraw over 2 mgd 

DIF; Uniform Impingement MortalityBTA standards for impingement mortality and 

Entrainment Controls for All New Units at Existing Facilities). How these vary from 

Proposal Option 1 is further described here. The remainder of this section explains EPA’s 

rationaleentrainment for selecting this option for the final rulenew units at existing 
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facilities. The previous section described the other options that EPA considered but 

ultimately rejected, and the basis for those decisions. 

1. Impingement Mortality Controls for Existing Units at Existing Facilities for the 

Final Rule. 

Today’s final rule allowsprovides a facility a number of alternatives for 

complying with the BTA impingement mortality standard. As discussed more below, 

EPA’s BTA impingement mortality standard is based on EPA’s conclusion that, on a 

national basis, modified traveling screens with fish-friendly return systems are the best 

performing technology available for impingement mortality reduction. But EPA is not 

requiring compliance with the BTA impingement mortality standards only through 

monitoring data showingthat demonstrates achievement of the numeric reduction in 

mortality levels that EPA has determined well-operated modified traveling screen will 

achieve. Rather, the final rule allows facilities to comply with the impingement mortality 

standards by employing any of seven alternatives, including monitored compliance with a 

numeric impingement mortality performance standard. Based on its analysis, EPA 

identified a number of other technologies and operational measures that could achieve 

equivalent, or better, performance to the impingement mortality controls achieved with 

modified traveling screens. Thus, the final rule provide for use of these alternatives to 

comply with the BTA impingement mortality standards.

TheBased 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 
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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. These include fourthree compliance paths based on “pre-approved”

technologies, and twothree 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 (see Exhibit VIII-1 for more 

information). 

The following are pre-approved technologies which allow for compliancewill 

comply with today’s rule throughand are associated with minimal monitoring and 

reporting of operational and/or design parameters. 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; 

(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; 

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 

fourthree pre-approved compliance alternatives are each based on a particular technology 

approach (. The permit for example closed-cycle recirculating systems such as wet 

cooling towers, design intake velocity such as a cylindrical wedgewire screen, actual 
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intake velocity, and existing offshore velocity caps). Aeach compliance alternative based 

on a pre-approved technology entails will necessarily include criteria, design standards, 

and operational measures in the regulatory languageconditions specific to the preapproved 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,), documentation, or reduced monitoring, and will therefore poseresult in

greatly simplified implementation. In today’s final rule, there are no biological 

compliance monitoring requirements for any of the fourthree compliance paths based on 

“pre-approved” technologies. 

The two “Under the streamlined” alternatives, a facility must demonstrate to the 

Director that traveling screens or some combination of technology controls or operational 

measures represent BTA performance under the conditions at the site. The three 

streamlined compliance alternatives includeare (the numbering reflects the numbering in 

§ 125.94(c)) operating (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) modified traveling screens whose demonstrated performance 

isrepresents the best technology available for impingement reduction at the site; or (6) a 

system or combination of technologies or operational measures whose demonstrated 

performance is the best technology available for impingement reduction at the site. In 

order to demonstrate under either (5) or (6), that the screens or other measures are BTA at 

the siteperformance, a facility will need to conduct a 2two-year site-specific study at the 

same time it conducts its source water characterization and entrainment 
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characterizationEntrainment Characterization Study. This study to ensuremust 

demonstrate that its modified traveling screens, or systemcombination of 

technologiestechnology controls and operational measures, have been adjusted and 

optimized so as to minimize impingement mortality. If this demonstration is madeIf 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 its permits as compared to a facility that complies using the numeric 

impingement mortality reduction performance standard. If the screens or other measures 

are not already installed, the Director may approve postponing the two-year study to be 

conducted after the entrainment determination has been made. These two “three 

streamlined” compliance alternatives are based on a collectiontechnology or suite of 

technologies and practices with more variable performance, and as such necessitate some 

degree of study, such as optimization of thein order to optimize technology performance 

for the site-specific 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 a pre-approved 

alternative.or better than the impingement mortality performance standard. For example, 

the streamlined compliance alternatives also do not require biological compliance 

monitoring. 

The seventh alternative (at § 125.94(c)(7)) for complying with the BTA 

impingement mortality standards requires the owner or operator to conduct biological 
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compliance monitoring 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 

performance standard is achieved. Further 

Each of these seven alternatives is further described below. In addition, further

discussion of how each of these alternatives will be implemented may be found in 

Section VIII. 

a. Closed-Cycle Recirculating Systems 

As described above, in Chapter 6 of the TDD, and in prior rulemakings, EPA has 

long recognized the benefits of flow reduction from closed-cycle recirculating systems 

for reducing impingement (as well as entrainment). A facility employing a closed-cycle 

recirculating system will typically reduce impingement by more than 95 percent. As a 

result, a facility may choose to comply with the BTA impingement mortality standards in 

today’s final rule by demonstrating that it uses a properly operated and maintained 

closed-cycle recirculating system. 

EPA estimates that approximately 18 percent of intake structures (i.e., those that 

already have an existing closed-cycle recirculating system, plus facilities located in 

California and New York, whose State regulations are at least as stringent as the final 

rule) will choose this alternative. 

However, as discussed in Section II above, EPA hasdoes not attempted to define 

allhave the data to determine precisely which impoundments usedare serving as part of a 
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closed-cycle recirculating system as a heat sink as closed-cycle recirculating systems; 

only thosedefined at 40 CFR 125.92(c)(2). However, EPA is aware that some facilities 

have created their impoundments that are not themselves waters of the U.S. and that can 

be demonstrated to the Director’s satisfaction to minimize cooling in a water withdrawals 

from waters of the U.S. will be considered to meet as part of their cooling system. EPA 

does not intend to eliminate the use of such lawfully created impoundments for their 

intended purpose, as doing so could result in a large number of stranded assets. If the 

cooling system with the impoundment minimizes the withdrawal of make-up water for 

cooling purposes, the Director may determine the cooling system meets the definition of 

a closed-cycle recirculating system. 

b. Reduced Intake Velocity 

EPA has long recognized the relationship between impingement and intake 

velocity. EPA conducted an analysis of fish swim speeds in the Phase I rule (see 66 FR 

65274, December 18, 2001) and concluded that a design through-screen velocity of 0.5 

fps is protective of 96 percent of motile organisms. However, EPA did not select intake 

velocity as the sole technology basis for the BTA impingement mortality standards. 

Although the performance of 0.5 fps intake velocity achieves greater reduction in 

impingement mortality than the technology on which the BTA impingement mortality 

standards are based, reducing a facility’s intake velocity is not widely available or 

feasible for all existing facilities (see Chapter 6 of the TDD). 

EPA concluded that it should allow facilities to complyis including reductions in 

intake velocity as an alternative for complying with the BTA impingement mortality 
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standards through reduced intake velocity. As a result, a A facility may choose to comply 

with the impingement mortality standards in today’s final rule by instead 

demonstratingchoosing this alternative must demonstrate that (1) the through-screen 

design velocity could not exceed 0.5 fps or (2) the actual intake velocity does not exceed 

0.5 fps. 

EPA estimates that approximately 34 percent of intake structures will choose this 

alternative. This estimate includes facilities that have an existing intake velocity of 0.5 

fps or less, plus those facilities that are projected to install a technology that would reduce 

their intake velocity (larger intake, wedgewire screens, or variable speed pumps). 

i. Design Intake Flow Basis 

Consistent with EPA’s determination in its earlier 316(b) regulatory efforts, the 

final rule allows a facility to comply with the BTA impingement mortality standards by 

demonstrating that its intake has a maximum through-screen design velocity of 0.5 fps.

EPA concluded that facility’s operating at this through-screen design velocity will protect 

the vast majority of impingeable aquatic organisms. Facilities choosing to comply with 

the BTA impingement mortality standards may not average velocity across multiple 

intakes at a facility. 

ii. Actual Intake Flow Basis 

EPA is also adopting a provision to allow facilities to demonstrate that the 

through-screen intake velocity at an intake structure does not exceed 0.5 fps on the basis 

of the intake’s actual flow. (Again, note that facility’sfacilities choosing this compliance 

alternative may not average intake velocity across multiple intakes.) In contrast to design 
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flow, where the intake velocity can never exceed 0.5 fps above, a facility with an intake 

that hashaving a design through-screen intake velocity greater than 0.5 fps may be 

operatingoperated at a reduced capacity and therefore may be withdrawingwithdraw

cooling water at a velocity less than 0.5 fps. As long as the actual intake flow is such that 

the velocity remains at or below 0.5 fps, the reductions in impingement (and 

subsequently, impingement mortality) remain the same as a facility with a maximum 

design through-screen intake velocity of 0.5 fps. As described below, a facility will be 

required to monitor its intake flow and report this data to the Director to verify that intake 

flows do not exceed 0.5 fps. This approach also permits the Director to allow brief 

periods where the intake velocity will exceed 0.5 fps under extreme conditions. 

c. Existing Offshore Velocity Caps 

A number of commenters stated that EPA should consider existing offshore 

intakes fitted with velocity caps “to be pre-approved” as and complying with the BTA 

impingement mortality standards. EPALocating submerged intakes in the deeper regions 

of larger waterbodies (particularly outside the littoral zone85) has the potential to reduce 

both impingement and entrainment (I&E), due to the lower densities of aquatic organisms 

as compared to a shoreline-based intake. EPA has identified 11 facilities with offshore 

velocity caps, and reviewed a number of studies documenting the performance of these 

facilities with velocity caps. These studies show that the impingement reduction 

 

85 The littoral zone extends from the shoreline to roughly the edge of the continental shelf. 
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performance of intakes submerged far offshore with velocity caps is dependent on sitespecific conditions. The data suggestshow that solely locating an intake far offshore (i.e., 

without also employing a velocity cap) mightachieves a 60 to 73 percent reduction in 

impingement, and therefore does not, in every circumstance, achieve impingement 

mortality reduction comparable to that of well-operated modified traveling screens. 

Similarly, the data also suggestshow that velocity caps alone achieve a 50 to 97 percent 

reduction in impingement, and therefore could result in compliance performance 

comparable to or better than modified traveling screens in some, but not in all cases. 

However, all available data shows the combination of an existing intake located far 

offshore (i.e., a minimum distance ofapproximately 850 feet, as identified in the data for 

Nine Mile Unit 1 and Oswego Unit 5) in combination with use of a velocity cap will 

result in performance that exceeds the annual12-month average impingement mortality 

performance standard (alternative seven described above).86,87 Because there is some 

amount of uncertainty in measuring distances from a shoreline, including but not limited 

to due to variations in water levels, storm swells, or tidal excursions, EPA has set the 

minimum distance offshore at 800 feet. As a result, the final rule at § 122.95(c)(4) allows 

a facility to comply with the BTA impingement mortality standards with an existing 

 

86 An existing facility may also choose to install a new offshore intake with a velocity cap, but such a 

facility would not automatically qualify as meeting the impingement requirements for the final rule. Such a 

facility would need to demonstrate equivalent performance to the impingement mortality limit.performance 

standard.

87 A velocity cap must also include bar racks or other devices to exclude large marine organisms (e.g., 

seals, turtles) from entering the intake structure. 
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offshore intake with an existing velocity cap. located at least 800 feet offshore, based on 

the performance data from the 11 identified facilities. 

As noted above, the record shows all existing facilities with a velocity cap located 

at least 800 feet offshore will meet or exceed the 12-month average mortality 

performance standard of 125.94(c)(7). EPA does not have data showing velocity caps 

located at lesser distances offshore will consistently achieve the impingement mortality 

performance standards, but is aware that some facilities may be able to achieve the 

impingement mortality standards through a combination of technologies that includes an 

offshore location. For example, the Office of Naval Research states that the littoral zone 

in ocean environments generally extends from the shore to 600 ft out in the water (ONR 

2013). SEAMAP data in EPA’s record shows installing the intake to depths where there 

is a lower concentration of living organisms (i.e., at least 65 feet) is also expected to 

decrease environmental impacts associated with intake operations. Therefore, the final 

rule allows facilities with intake structures at significant distances offshore to 

demonstrate the performance of their technology under § 122.95(c)(6), as further 

discussed below. 

In addition facilities may opt to construct an offshore velocity cap at new 

locations. In those circumstances, the facility will need to demonstrate that the 

performancetheperformance of its velocity caps is the best technology available for 

impingement reduction under the alternative six found at § 122.95(c)(6). For more 

information, see DCN 12-[XXXvelocity cap data/memo].-6601.
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EPA estimates that approximately 1 percent of intake structures (i.e., those with 

an existing velocity cap meeting the definition at § 125.92(v) will choose this alternative. 

d. Install Modified Traveling Screens 

In the June 11, 2012 NODA, EPA discussed a “streamlined” compliance option 

that would provide facilities with a less burdensome alternative than the proposed rule. In 

the final rule, EPA has included thisan option in the final ruleat §125.95(c)(5) for 

facilities that install BTA.traveling screens – the technology that forms the basis for the 

numeric IM performance standards. Under this option, the facility must demonstrate to 

the Director that it will still submit the same application materials specified in § 

122.21(r)(2)-(5).install and operate modified traveling screens as defined at 125.92(s) that 

are or will be optimized to minimize IM mortality at the site. The facility will also be 

required to submit an impingement technology performance optimization study (§ 

122.21(r)(6)) which will include a 2-year optimization study for the intake technology. 

The facility will conduct 2 years of monthly impingement monitoringdata collection, 

during which the facility will seek to optimize the technology performance to minimize 

impingement mortality. This study is intended to determine the optimal configuration and 

operating conditions of modified traveling screens and the fish handling and return 

systems for that intake to be consistently protective of aquatic organisms. During the 

course of the study, EPA expects that a facility will evaluate the interim results and make 

changes to the technology or operating conditions as needed to identify the most 

appropriate set of operational characteristics to ensure long-term success. For example, a 

facility could adjust the spray wash pressure, adjust the rotating speed of the screens, 
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rotate the screens more frequently, re-angle the fish sluicing sprays, ensure adequate 

water in the return flume, design the fish return to avoid avian and animal predation on 

the aquatic organisms, and locate the fish return in such a way to avoid predation. Once a 

facility has optimized its technology performance, the study will identify operational 

measures that will serve as observable and enforceable permit conditions. As evidenced 

by the data used in determining the limitperformance standard, by requiring facilities to 

study the conditions for optimized performance, many facilities will achieve 

impingement mortality reductions much greater than the annual12-month average 

impingement mortality performance standard without significant additional investment. 

Biological monitoringdata collection beyond the application informationthis two-year 

study will not be required. The facility will simply be required to ensure that it is 

operating its technology under the identified conditions for optimized performance. TheIf 

the Director concludes that the screens will achieve optimized performance, the Director 

will also incorporate these operating conditions to ensure optimized performance as terms 

of the facility’s NPDES permit. 

As discussed in the NODA and Chapter 4 of TDD, EPA’s data indicate that most 

facilities employ traveling screens.88 EPA anticipates that, as a result, many facilities will 

view the streamlined screen-based compliance route as a logical choice for complying 

with the final rule. The streamlined option provides an opportunity for a large number of 

 

88 EPA’s technical survey found that 93 percent of electric generators and 73 percent of manufacturers 

already use screens, the majority of which are traveling screens. 
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the affected facilities (i.e., those that do not meet the criteria for the other compliance 

technologies) to demonstrate that their intakes are effectively reducing impingement 

mortality while significantly reducing the burden on both facilities and regulatory 

agencies. EPA estimates that approximately 30 percent of intake structures will choose 

this alternative.89

EPA also notes that the addition of observable and enforceable permit conditions 

constitutes a major revision to a facility’s NPDES permit and will therefore require that 

the changes be provided for public comment. 

EPA is aware that some facilities have no technologies installed and will choose 

to install modified traveling screens, and further that some facilities with traveling 

screens will choose to either retrofit to modified traveling screens with fish handling and 

returns. Obviously, the impingement technology performance optimization study cannot 

be undertaken until the technology is first installed. In this case the NPDES permit would 

be issued before the completion of the optimization study. EPA expects a permit will be 

issued that includes a schedule for both the technology installation and the required 

optimization study. As discussed earlier, the Director can establish interim measures as 

appropriate (40 CFR 125.94(b)). 

 

89 While EPA’s data shows 73 to 93 percent of facilities already use traveling screens, EPA notes that many 

facilities use more than one technology. For example, some of these facilities also have a low intake 

velocity, an offshore velocity cap, or cooling towers. EPA expects facilities will choose the IM compliance 

alternative corresponding to these pre-approved technologies before they will choose to comply via 

optimized performance of their traveling screens. 
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e. System of Technologies as the BTA for Impingement Mortality 

EPA recognizes that cooling water intake structures have a variety of 

configurations and facilities may choose to comply with the final rule by using more than 

one of the compliance approaches outlined above. In the June 11, 2012, NODA, EPA 

described an approach where facilities would be able to demonstrate “credit” toward 

meeting the impingement mortality requirements by reducing the total number of 

organisms impinged. EPA also intended for facilities to have the flexibility to employ any 

system of technologies or combination of operational measures to address impingement 

mortality so long as the performance of the selected impingement reduction measures 

represented the best technology available for the site. The final rule includes an 

alternative reflecting these objectives. 

In the broadest sense, facilities have a number of options for reducing 

impingement mortality. Some may choose to comply using a singlean approach, where a 

single technology achieves the level of compliance necessary. Others may choose to 

employan approach of employing multiple approachestechnologies or operational 

measures, including reducing the number of organisms that are impinged or even 

susceptible to being impinged. The following are examples of approaches for which a 

facility might be able to take credit for impingement reduction under this alternative: 

 Partial closed-cycle cooling 

 Variable speed pumps 
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 Seasonal outages (including standard maintenance outages that are specifically 

scheduled to avoid a biologically sensitive period) 

 Certain impingement technologies that reduce the number of organisms exposed 

to the intake structure (e.g., diversions, louvers, barrier nets) 

 Intake location 

 Behavioral technologies (e.g., light or sound barriers)90

In each case, the technology employed reduces the number of organisms that 

potentially are impinged, resulting in a reduction in the number of organisms actually

impinged (i.e., a reduction in the rate of impingement). By virtue of reducing the actual 

impingement, mortality caused by impingement is no longer a consideration—an 

organism that is never impinged cannot be killed by the intake structure. Some 

technologies work to reduce the intake flow, thereby reducing the potential organisms 

exposed to the intake. Others work to divert organisms away from the screens, either 

through a physical exclusion or by being placed in a less biologically productive area. 

EPA concluded that it is appropriate to recognize these reductions in impingement as a 

step in achieving ana BTA impingement mortality reduction performance that is the best 

technology available at a particular site. As a result, EPA expects the reduction in 

 

90 For example, anadromous clupieds such as alewife, blueback herring, and American shad have 

demonstrated avoidance behaviors when exposed to high frequency sound. Deployments of this technology 

at Entergy’s FitzPatrick Nuclear Station on Lake Ontario have resulted in a reduction of over 90 percent in 

impingement of alewife. In this case, EPA expects the Director would determine that impingement 

requirements regarding alewife have been addressed by the acoustical deterrent. The Director could 

disallow such a technology if it were deemed to have a negative effect on threatened or endangered species 

whose habitat includes the facility’s intake location.
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impingement will be treated as an equivalent reduction in impingement mortality, and the 

facility will therefore be considered by EPA or the State NPDES permitting authority in 

evaluating whether the system of technology and operational measures represented 

BTAchosen technologies and operational measures represent BTA performance under the 

site’s conditions. For example, an intake that operates infrequently due to the infrequent 

operation of the electric generating unit(s) it serves (such as a peaking unit) may use a 

relatively small amount of water on an annual basis when compared to the design 

capacity of the intake structure. This facility may choose to comply with the impingement 

mortality standard at (c)(6) by demonstrating to the Director that the facility operates at 

an annual intake flow that is less than or equal to 24 percent of its design intake flow on 

an annual basis. This level of flow reduction could achieve a level of performance 

equivalent to or better than the impingement mortality performance standard in (c)(7), 

and therefore could be considered to be compliant with the requirements of today’s final 

rule. This demonstration may include design data, several years of past operating data, 

and dispatch modeling. These operating conditions would then be incorporated into the 

NPDES permit. 

A facility complying under this part, must submit a impingement technology 

performance optimization study, which must include the calculated percent impingement 

mortality reflecting optimized operation of the system of technologies, operational 

measures, and best management practices and all supporting calculations. Total system 

performance is the combination of impingement mortality performance reflected in all of 

the following which apply: 
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 Rate of impingement – The estimated reductions in rate of impingement 

must be based on a comparison of the system to a once-through cooling 

system with a traveling screen whose point of withdrawal from the surface 

water source is located at the shoreline of the source waterbody. For 

impoundments that include waters of the United States, the facility’s rate 

of impingement must be measured at a location within the cooling water 

intake system that the Director deems appropriate.

 Impingement mortality – If the demonstration relies in part on a credit for 

reductions in impingement mortality already obtained at the facility, two 

years of biological monitoringdata collection must be provided, 

demonstrating the level of impingement mortality the system is capable of 

achieving. 

 Flow reduction – If the demonstration relies in part on flow reduction to 

reduce impingement, the data must include two years of intake flows, 

measured daily, as part of the demonstration. This must include 

documentation of how the flow reduction results in reduced impingement. 

The permitting authorities would consider this information shown in the two-year 

impingement technology performance optimization study that must be submitted under 

this alternative. For example, at facilities choosing to comply by demonstrating that they 

are operating below 24 percent of their intake capacity, or that they are peaking units, the 

Director should use this study to establish operating conditions that ensure that the intake 
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continues to operate below 24 percent of its intake capacity or continues to serve only 

peaking units and that these units are not later used as intermediate or baseload units. 

The operating conditions and parameters identified in the study will then be incorporated 

in the facility’s permit conditions. EPA estimates that approximately 17 percent of intake 

structures will choose this alternative. 

f. Achieve ComplianceComply with the Numeric Impingement Mortality 

Performance Standard 

Facilities complying with the BTA impingement mortality standards 

throughstandard by achieving the numeric performance standard alternative at § 

125.94(c)(7) will perform monthly compliance monitoring to verify that the annual 

average12 month percent impingement mortality rate resulting from operation of its 

intake is below the standard established in today’s final rule. (For more details on 

complying with the impingement requirements, see sectionSection VIII.) EPA expects 

that, save for future technologies or innovations, few facilities will avail themselves of 

this option. 

2. Entrainment Controls for Existing Units at Existing Facilities 

The BTA entrainment standard for the final rule set in placeestablishes a 

structureframework under which EPA or the State NPDES permitting authority must 

establish site-specific BTA entrainment requirements for each facility above 2 mgd 

DIF.in the scope of today’s rule. EPA considered promulgating no further controls to 

address entrainment mortality, and to rely instead only on the BTA impingement 

mortality controls, which would achieve up to a 3134 percent reduction in total AEI. EPA 
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did not select this option as the basis for national BTA because, in EPA’s view, some 

facilities either are having a significant impact as a result of entrainment or might be able 

to do more to control entrainment at costs that are low relative to benefits. In addition, 

EPA’s data on entrainment at facilities are not sufficient to allow the Agency to 

categorize facilities requiring no additional controls for entrainment. Thus, the final rule 

by requiring prescribed information in the permit application will provide the Director 

with adequate information for decision making. 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 sitespecific analysis could be that the Director would determine that no other technologies 

beyond impingement control meet the criteriacontrols are required for selection as BTA, 

entrainment reductions, either because no other technologiesthey are not feasible and/or 

theirbecause the social costs of additional control measures are not justified by the social

benefits do not justify their costs.. 

In the case of site-specific entrainment controls for facilities withdrawing greater 

than 125 mgd AIF, the final rule requires themfacilities to also develop and submit an 

entrainment characterization studyEntrainment Characterization Study and related 

supporting information, as described in § 122.21(r)(9)-(13) of today’s rule, for use by the 

Director in establishing site-specific BTA. (Facilities at or under the 125 mgd AIF 

threshold must still provide certain information under the existing permit application 

requirements at § 122.21(r). The Director may also require these facilities to submit the 

studies at § 122.21(r)(9)-(13) if there is reasonable concern over entrainment impacts at 
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the facility.)For facilities above 125 mgd AIF that also meet the definition of closed-cycle 

recirculating systems at § 125.92(c), the Director may reduce or waive some or all of this 

information. 

 EPA considered simply requiring this information of all facilities above 125 mgd 

AIF without authorizing Directors to reduce or waive this information. However, EPA 

also recognizes that, in some instances, these same facilities have already minimized 

adverse environmental impacts significantly. In such cases, there may be limited value to 

the Director requiring a full benefit-cost analysis, or even obtaining the Entrainment 

Characterization Study at (r)(9). 

EPA also considered not requiring this information of any facilities above 125 

mgd AIF meeting the definition at § 125.92(c). First, EPA noted that even though these 

facilities meet the definition of a closed-cycle recirculating system, they may still 

withdraw at least 125 mgd, and in some instances withdraw considerably more than 125 

mgd. This is not an insubstantial volume of water withdrawn for cooling, and in the case 

of inland waters this withdrawal may comprise a large proportion of that source 

waterbody. In addition to withdrawing large volumes of water, EPA recognizes that some 

facilities, particularly those meeting the definition at § 125.92(c)(2), potentially withdraw 

water at a rate similar to a once-through facility not withdrawing from an impoundment, 

with the potential to cause adverse environmental impacts similar to those of oncethrough cooling. The Director may find the information in § 122.21(r)(9)-(13) to be 

useful in determining whether additional controls are warranted. In these instances, the 
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Director may decide to require the Entrainment Characterization Study at (r)(9) first, in 

order to determine if other studies in (r)(10) to (13) are also warranted. 

Facilities at or under the 125 mgd AIF threshold must still provide certain 

information under the permit application requirements at § 122.21(r). The Director may 

require additional information from these facilities including some or all of the studies at 

§ 122.21(r)(9)-(13) if there is reasonable concern regarding entrainment impacts at the 

facility. Where an owner or operator of a facility intends to comply with the BTA 

standards for entrainment using a closed-cycle recirculating system as defined in § 

125.92(c), the Director may reduce or waive some or all of this information. 

 Facilities with a closed-cycle recirculating system as defined at § 125.92(c)(2) 

would still submit the studies at § 122.21(r)(9)-(13) if they withdraw greater than 125 

mgd AIF, and if the Director has not waived the requirements. These facilities have 

cooling systems that include impoundments of waters of the U.S. where the 

impoundment(s) was constructed prior to [INSERT effective date of the final rule] and 

lawfully created for the purpose of serving as part of the cooling water system. This 

purpose must be documented to the Director's satisfaction in the project purpose 

statement of any required Clean Water Act section 404 permit obtained to construct the 

impoundment. In the case of an impoundment whose construction pre-dated the CWA 

requirement to obtain a section 404 permit, where alternative permitting documents were 

required, the facility must document the project’s purposes to the satisfaction of the 

Director by some other license or permit obtained to lawfully construct the impoundment 

for the purposes of a cooling water system. EPA notes that for impoundments 
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constructed in uplands or not in waters of the United States, no documentation of a 

section 404 or other permit is required. EPA received comments that such impoundments 

should be treated as closed-cycle cooling and has agreed to make this change. The 

Director would still make the determination that make-up water withdraws have been 

minimized. Further, EPA’s data shows that many facilities that utilize impoundments as 

part of their cooling water systems may actually use a combination of cooling water 

systems (for example, detailed survey responses showed eight facilities with an 

impoundment in addition to other IM technologies). The requirement that these facilities 

provide the Director with certain information will help ensure that the Director has 

adequate information upon which to base a decision for these impoundments as to 

whether these facilities have adequate controls already or should be taking additional 

measures to protect the relevant waterbody. 

 The Entrainment Characterization Study will include information already 

collected to meet existing § 122.21(r)(4) requirements. In addition, under the new permit 

application requirements being added today at § 122.21(r)(5)-() to (13), the facility will 

submit certain additional site-specific information. This will include an engineering study 

of the technical feasibility and incremental costs of candidate entrainment mortality 

control technologies. The facility will also study, evaluate, and document the technical 

feasibility of technologies, at a minimum, including closed-cycle cooling, fine mesh 

screens with a mesh size of 2 mm or smaller, and water reuse or alternate sources; 

[NOTE to reviewers: EPA would like to cite here as support for this material the draft 

DOE report on “U.S. Energy Sector Vulnerabilities to Climate Change and Extreme 
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Weather” when it is public.] engineering cost estimates of all technologies considered; 

any outages, downtime, or other effects on revenue along with a discussion of all 

reasonable attempts to mitigate these cost factors; and a discussion of the magnitude of 

water quality and other benefits, both monetized and nonmonetized, of the candidate 

entrainment mortality reduction technologies evaluated. Finally, the information must 

include a discussion of the changes in non-water quality environmental impacts attributed 

to technologies and/or operational measures considered. The factors include, for example, 

increases and decreases in the following: energy consumption, and air pollutant emissions 

including particulates and associated human health and global climate change impacts, 

water consumption, noise, safety (e.g., visibility of cooling tower plumes, icing), grid 

reliability, and facility reliability. For a thorough discussion of these study requirements, 

see Section IXVIII. The final rule also requires peer review of the Comprehensive 

Technical Feasibility and Cost Evaluation Study, Benefits Valuation Study, and NonWater Quality and Other Impacts Assessment. Peer review of the Entrainment 

Characterization Study. is not required. Note that the peer reviewed studies will rely on 

data gathered in the Entrainment Characterization Study. Peer reviewers will be selected 

in consultation with the Director, who can also consult with EPA and federalFederal, 

State, and Tribal fish and wildlife management agencies with responsibility for fish and 

wildlife potentially affected by the cooling water intake structure(s). 

Under the final rule, EPA expects that the Director will review the candidate 

technologies for entrainment mortality control that, at a minimum, includes closed-cycle 

cooling and recirculating systems, fine-mesh screens. with a mesh size of 2 mm or 
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smaller, and water reuse or alternate sources. In the decision about what additional 

entrainment controls (if any) to require, the Director will consider all the facility-specific 

factors in § 125.98(f)(2) and described above. At a minimum, the Director must provide a 

discussion explaining how issues concerning air emissions or land availability, insofar as 

they relate to the feasibility of adoption of an entrainment technology, and remaining 

useful plant life, were addressed in the site-specific determination. Under the final rule, 

the Director must issue a written explanation for the basis of the BTA entrainment 

determination for each facility. EPA also expects that the The Director’s decision must 

include a written explanation willthat, at a minimum, includeincludes consideration of the 

following factors: (i) numbers and types of organisms entrained; (ii) impact of changes in 

particulate emissions or other pollutants associated with entrainment technologies; (iii) 

land availability inasmuch as it relates to the feasibility of entrainment technology; and 

(iv) remaining useful plant life.; and (v) social costs and benefits, which may include 

qualitative, quantified and monetized categories. The Director may also base the 

proposed determination on several other factors, including a review of the social costs 

(and not just the facility costs—see Chapter 8 of the EA) of the various technologies; a 

review of the potential reductions in entrainment and entrainment mortality;thermal 

effects and a review and analysis of monetized and nonmonetized benefitswater 

consumption. 

In addition to the information required for development of impingement controls 

discussed above, under the authority granted to EPA in CWA sections 301, 308, 316(b), 

and 402, 401, 510regulation also requires, in the case of facilities withdrawing greater 
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than 125 mgd AIF, the submission of certain other information for use in the site-specific 

entrainment determination of BTA will be based on a submission of certain other 

required information.. The final rule also adds the permit application requirements at § 

122.21(r)(7) and) (9)-(13) to require the facility to prepare several studies, including an 

Entrainment Characterization Study, that will fully characterize the extent of entrainment 

at the facility. (For more details about the study, see belowabove). In addition, under the 

final rule, the facility will provide detailed information on the other factors relevant to the 

Director’s site-specific BTA determination. These will include information concerning 

the technologies available for control of such entrainment, the costs of controls, the nonwater quality environmental impacts of such controls, the monetized and nonmonetized 

benefits of such controls, and the presence of any threatened and endangered species. 

EPA encourages, and the CWA requires, the public to have a role in the permitting 

process.The final rule does not limit the Director’s discretion to consider non-water 

quality impacts in determining whether further entrainment measures are justified. EPA 

encourages, and the CWA requires, the public to have a role in the permitting process. 

Interested members of the public may submit written comments on a draft permit during 

the 30 day public notice and comment period and request a public hearing on a draft 

permit. For permits that are issued by EPA instead of a state, additional opportunities for 

public involvement include comment, and in some cases, a public hearing on a 

permittee’s State Water Quality Certification under section 401 of the CWA. (See 40 

CFR 124.10, 124.11, 124.12(a) and 124.17(a).) Therefore, the final rule clearly affords 
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the public a meaningful opportunity for participation in the site-specific decision making 

to help ensure the soundness of both the information and subsequent determinations. 

3. Impingement Mortality and Entrainment Controls for New Units at Existing 

Facilities 

Under the final rule, a new unit at an existing facility that withdraws more than 

2 mgd will have requirements similar to the requirements of a new facility in Phase I. 

Under the rule, a new unit (as defined at § 125.92 and described above) is required to 

reduce flow commensurate with a closed-cycle recirculating system as would be applied 

to the new unit. As with Track II of the Phase I rule, a facility could demonstrate 

compliance with the new unit entrainment standards by establishing reductions in 

entrainment mortality for the new unit that are 90 percent of the reductions that would be 

achieved by closed-cycle cooling. 

EPA has promulgated requirements that establish two types of units that will be 

defined as a new unit at an existing facility. First, a newly built, stand-alone unit that is 

constructed at an existing facility (and that does not meet the definition of a new facility) 

will be defined as a new unit. Second, an existing unit that is repowered and undergoes 

significant modifications, to a degree where both the turbine and condenser are replaced, 

will also be considered a new unit at an existing facility. Under the second category, 

several types of modifications will not cause the unit to be considered as a new unit, 

thereby defining the unit as an existing unit. Also, the final rule excludes high energy 

efficiency units from the definition of new units. In these cases, the existing unit will be 

regulated under the provisions applicable to existing facilities, and the unit will not be 
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subject to categorical requirements to reduce intake flow to a level commensurate with 

closed-cycle cooling. 

Where manufacturers may generate electricity onsite, the previous discussion 

applies. Some manufacturers employ different industrial processes than an electric 

generator and therefore have different industrial equipment (including cooling systems). 

In the case of manufacturing equipment that does not generate electricity onsite, a new 

unit is defined as any newly built production unit or replacement unit where 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 noncontact cooling water are newly installed or replaced. 

EPA is adopting more stringent requirements for new units at existing facilities 

because these facilities have the ideal opportunity to design and construct the new 

units without many of the additional expenses and operational disadvantages 

associated with retrofitting an existing unit to closed-cycle cooling. H. Economic 

and Benefit Analysis for the Final Rule 

For example, the incremental downtime that can be associated with retrofitting to 

closed-cycle cooling is avoided altogether at a new unit. In addition, when new units are 

added, the condensers can be configured for closed-cycle, reducing energy requirements 

and substantially reducing the turbine backpressure energy penalty. High-efficiency 

cooling towers can also be designed as part of the new unit, allowing for smaller cooling 
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towers. As a result, the capital costs for installing closed-cycle cooling at new units are 

lower than the capital costs for installing once-through cooling.91 (See DCN 10-6651.) 

As discussed below, the three factors that led EPA to reject closed-cycle cooling as 

BTA are far less relevant for new units at existing facilities than for retrofitting existing 

units. This section discusses why EPA concluded that each factor is not a significant 

concern for new units, and why the record supports EPA’s conclusion that closed-cycle 

cooling is an available and feasible technology for new units at existing facilities.

 Land Availability: In contrast to existing units, the amount of space dedicated to 

closed-cycle for new units will be limited to the new unit rather than the entire 

facility. As a result, space constraints will be much less of an issue. New units 

also present the opportunity to design an optimized closed-cycle recirculating 

system for the new unit. Retrofitting an existing facility would require a facility to 

identify (or possibly obtain) enough space to accommodate the cooling towers 

and associated equipment. Furthermore, new units and their corresponding 

cooling system can also be built in stages rather than as a facility-wide retrofit. In 

addition, rebuilt, repowered, or replaced units are also considered new units with 

the exception of high energy efficiency units. Thus, there is always land available 

 

91 EPA recognizes that a facility might use an existing intake to supply water for a new unit. In this case, 

the construction costs for a once-through system are notably smaller than those for a closed-cycle system. 

However, in terms of the total project cost over the life of the new unit, these costs differences are minimal. 
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for repowering projects that are high energy efficiency units because they do not 

require land for wet cooling towers. 

 Increased Air Emissions: EPA expects that emissions are less of a concern at new 

units. The condensers can be optimized for closed-cycle, 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. Turbine backpressure and the associated energy penalty can be 

substantially reduced in a new unit, but new units will still have auxiliary power 

consumption for fans. Therefore energy penalties and air emissions for tower 

operations can be minimized (though not eliminated). The effects of requiring 

closed-cycle cooling at new units at existing facilities is similar to the effects of 

this requirement at new facilities and will not pose an unacceptable impact. For 

more information, see Chapters 6, 8, and 10 of the TDD. Finally, to encourage 

repowering projects that are beneficial from both a water and air perspective, EPA 

is exempting rebuilt, repowered, or replaced units that are high energy efficiency 

units from the closed-cycle requirement. 

 Remaining Useful Plant Life: This is clearly not an issue for new units. A new 

unit has its full useful life remaining and thus would experience the maximum 

possible entrainment mortality reductions throughout that useful life. 

The considerations discussed above regarding current transmission capacity for 

existing units would not apply in the case of installing new units because there will be no 

downtime for new units, as they have not begun operating. Therefore, there is no 
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potential for local transmission capacity to be compromised. In fact, local transmission 

capacity is likely to be improved with the addition of the new unit, even if older units are 

later retired. 

In the final rule, EPA is excluding rebuilt, replaced, and repowered high energy 

efficiency new units from the new unit entrainment standard applicable to other new units 

in order to create an incentive for their use. Information in the record indicates that the 

most effective way to reduce cooling water intake is through the use of high efficiency 

units because these units require less cooling water per unit of energy produced. 

Repowering from lower efficiency units to high energy efficiency units could reduce 

water withdrawals by 50 percent for the same electricity output. [See DCN 12-XXX turn 

Air email and TT analysis into a memo.] Other environmental benefits result from the 

use of high efficiency units, such as reduced thermal loads to receiving waters, 

greenhouse gases, and decreased emissions of NOx, SO2, PM2.5 and Hg, depending on 

the baseline fuel and efficiency. Recognizing that section 316(b) confers “some discretion 

to determine the extent of reduction that is warranted under the circumstances” (See 

Entergy, 556 U.S. at 208) and recognizing the environmental benefits achieved by 

replacing less efficient units with high efficiency new units, the Agency has determined 

that requiring these high efficiency new units to incur the cost of the requirements for 

entrainment applicable to other new units in § 125.94(e) is not warranted. 

EPA does not expect that the requirements for new units at existing facilities will 

be a disincentive for facilities to repower existing units. As described above, the 

requirements do not apply to high efficiency new units. As described in section II.H, EPA 
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has crafted the definition of a new unit at an existing facility to only capture those 

facilities that undergo large-scale modifications (i.e., replacing both the turbine and 

condenser). As a result, smaller-scale repowering efforts will be unaffected by the final 

rule. For facilities that do choose to repower an existing unit, the costs of employing a 

closed-cycle cooling system are not a barrier, as described above. In fact, some facilities 

may find closed-cycle cooling to be less costly over the long-term.

EPA also recognizes that installing closed-cycle cooling systems at new units is a 

prevailing trend in industry, regardless of the regulatory requirements imposed by today’s 

final rule. For example, see DCN 12-[XXXEIAdatamemo] in the record for today’s rule, 

and DCNs 2-009 and 4-4023C (from the Phase I and Phase II dockets, respectively). 

These documents show that, on the basis of responses from facilities to the 316(b) 

industry questionnaire, facilities constructed in recent years are significantly more likely 

to employ closed-cycle cooling.

EPA recognizes that at some point in the future, every unit will be rebuilt, 

replaced or repowered. EPA projects that approximately 0.5 new units per year, out of a 

total of 7.0 new units per year, will be subject to the new unit provision, reflecting the 

general industry trend towards more efficient repowerings. 

EPA notes that the new unit provision is an important element of the final rule, 

given the generally long lifespan of equipment at industrial facilities. For example, 

generating units at a power plant are often projected to have a 50-year lifespan. As a 

result, these facilities have a slow rate of “evolution” in adopting newer technologies. By 
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requiring closed-cycle cooling in new units, EPA is contributing to the advancement of 

the time frame for the nationwide transition to closed-cycle cooling. 

F. Economic Analysis for the Final Rule 

1. Economic Justification for the Final Rule 

Pursuant to the principles spelled out in E.O. 12866 and E.O. 13563, EPA has 

assessed costs and benefits for the final rule and has reasonably determined that the 

benefits of the rule justify the costs. EPA has estimated the social cost of this rule to be 

$297275 million annually. For more information on EPA’s analysis of the rule’s costs, 

see Section IX. 

As described in more detail below in Section X, significant benefits are associated 

with the rule. These benefits include the annual reduction in impingement mortality of 

576652 million age-one equivalents for existing units. There are, in addition, other 

important benefits, many of which EPA cannot quantify. These benefits include effects 

on many shellfish species and nonuse values associated with the vast majority of fish and 

shellfish. The rule also requires establishing site-specific entrainment controls through a 

process in which specific environmental conditions and the localized benefits of 

entrainment reductions will be assessed along with the costs of controls. The information 

generated in the required studies will enhance the transparency of decision making and 

provide an opportunity for meaningful public participation, ensuring that decision making 

is based on the best available data. Overall, these requirements and subsequent Director 

actions under this rule will foster protection and restoration of healthy aquatic ecosystems 

that have important commercial, recreational, aesthetic and cultural values to their 
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surrounding communities. Many of the benefits that will result from the rule are not 

monetized or quantified, and as a result the Agency’s monetized benefits analysis 

underestimates the totality of the rule’s benefits. On the basis of the record, EPA has 

determined that the impingement mortality and entrainment controls will result in 

benefits that justify the costs of the rule. 

EPA also notes that it was able to generate only a partial estimate of benefits for 

today’s 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 valued. These categories 

of benefits thatwhich are not fully valued are often referred to as nonuse benefits – i.e., 

benefits that people derive apart from the value of using an affected resource, such as 

fishing. For example, nonuse benefits would include the value that individuals place on 

knowing that an aquatic ecosystem is healthy. EPA conducted a nonuse benefits transfer 

for nonuse values using an existing valuation study, but was able to estimate values only 

for one based on a species for households in northeast and middle Atlantic statesthat 

represents less than one percent of adverse environmental impacts. EPA developed and 

implemented an original stated preference survey to estimate total values (use plus 

nonuse values) for aquatic resource improvements under 316(b) regulatory options. 

However, EPA has decided not to haveemploy the SAB review the analysis of the stated 
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preference survey results, and address whether it is appropriate for use in site-specific 

purposes of decision-making. and EPA has not accounted for values estimated from the 

survey in the quantitative comparison of costs and benefits. It is also important to note 

that EPA’s stated preference survey was designed to estimate respondents' willingness to 

pay for changes in the health of fish populations and aquatic ecosystems and to be 

statistically representative at large (regional and national) scales; the results were not 

specifically designed to be statistically representative at the facility level for the 

assessment of benefits for individual site-level permitting decisions.

As noted at the outset, it is not always the case that private decision making 

regarding withdrawals of cooling water takes into account society’s preferences for fish 

protection, nor are there market transaction opportunities for private citizensindividuals

to express their willing to pay for fish protection. Thus, despite the limited information on 

monetized social benefits, EPA has concluded that the benefits of today’s rule justify the 

costs of today’s rule. 

2. Comparison of the PrimaryOther Options 

As discussed above, EPA considered three other primary options before selecting 

a modified version of Proposal Option 1for today’s rule. See Section VI.F Other Options 

Considered for more detailed explanation of each option. Exhibit VI-1 illustrates a 

comparison of the total annualized social costs and benefits. 

Exhibit VI-1. Comparison of the primary options for existing facilities316(b) ($2011 millions at 2013, 3% 

discount rate) 

Option Total Annualized Social Cost Monetized Benefits 
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Proposal Option 4 $261.7251.8 $20.231.0

Final Rule $283.3274.9 $20.432.8

Proposal Option 2 $3,999.73643.2 -$1,0441542.6 

GI. Site-Specific Consideration of Entrainment Controls 

As described above, EPA is not promulgating uniform national requirements for 

entrainment. for existing facilities. Instead, EPA is setting standards for entrainment that 

include a framework by which a facility will be subject to a site-specific determination by 

EPA or a State NPDES permitting authority of appropriate BTA requirements for 

entrainment. This section describes the process for determining section 316(b) 

requirements for an individual facility under the national BTA standard for entrainment. 

It describes the elements that the Director must consider in the permitting decision and 

how costs and benefits may be considered in such an evaluation. 

1. Implementation of a Site-Specific Evaluation of Entrainment for Existing 

Facilities

The final rule requires a site-specific determination of BTA entrainment 

conditions in individual permits and prescribes the requirements for that permitting 

proceeding. The final rule includes permit application requirements for facilities with a 

cooling water intake structure. These requirements are designed to elicit the information 

the Director needs to determine what is the best technology for reducing entrainment for 
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a particular facility, including information pertinent to an assessment of whether the 

benefits justify the costs of any particular control measures under consideration. 

Today’s final rule is a modification of Proposal Option 1’sthe proposed approach 

of a site-specific BTA entrainment determination. It will result in one of two outcomes at 

any facility: 

1. Determination that the facility must install additional control measures that reduce 

entrainment beyond that achieved by the currently installed equipment. These 

may include closed-cycle cooling and/or other technologies. 

2. Determination that the facility’s current, existing technology for entrainment 

achieves the entrainment BTA requirements under the national BTA standard

based on site-specific information not available to EPA today. 

Thus, EPA expects that, under this approach, there will be additional entrainment 

controls for some facilities and none for others. Even where the Director’s determination 

requires no additional control measures, the Director may conclude the permit should 

include conditions that specify proper operation and maintenance of the installed 

technology. 

EPA notes that in a number of areas of the country (California, Delaware, New 

York, and New England; see, for example, DCNs 10-6963 and 10-6841, and EPA Region 

I’s Brayton Point), permitting authorities have already required or are considering 

requiring existing facilities to install or retrofit to closed-cycle cooling systems. These 

facilities are still subject to the federaltoday’s rule but the stateexisting requirements have 
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been consideredtaken into account in costing. Also, § 122.21(r)(1) and § 125.98(g) were 

added to address the application requirements and permit proceedings for the facilities...

For facilities that withdraw more than 125 mgd, the rule generally requires that 

the facility conduct an ECS (Entrainment Characterization Study) entrainment study as 

part of its permit application. The study will indicate, at a minimum, the specific 

entrainment monitoringdata collection methods, taxonomic identification to the lowest 

taxon possible, latent mortality identification, documentation of all methods, and quality 

assurance/quality control procedures for sampling and data analysis appropriate for a 

quantitative survey. The rule also requires a peer review of the Entrainment 

Characterization Study. Peer reviewers must be selected in consultation with the Director, 

who may consult with EPA and Federal, State, and Tribal fish and wildlife management 

agencies with responsibility for fish and wildlife potentially affected by the cooling water 

intake structure. Data from the ECS entrainment study is important to provide 

corroboration of any through-plantfacility entrainment survival study results in § 

122.21(r)(7) or from any other studies conducted. 

The final rule also requires the permit application to include the following 

information (foras part of the entrainment study (which refers to the requirements at § 

122.21(r)(9) through (13), as opposed to the Entrainment Characterization Study at 

(r)(9)). For a thorough discussion of these study requirements, see Section VIII)::

 An engineering study of the technical feasibility and estimated costs of all 

candidate entrainment control technologies, including closed-cycle cooling, fine-
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mesh screens with a mesh size of 2 mm or smaller, and water reuse or alternative 

sources; 

 A discussion of any outages, downtime, or other effects on revenue along with a 

discussion of all reasonable attempts to mitigate these cost factors 

 A discussion of the magnitude of water quality benefits, bothwhether qualitative, 

quantitative or monetized and nonmonetized, of the candidate entrainment 

reduction technologies evaluated; thermal discharges; and 

 A discussion of the changes in non-water quality environmental impacts and other 

factors attributed to technologies and/or operational measures considered, 

including, for example, increases and decreases in the following: energy 

consumption; thermal discharges; air pollutant emissions including particulates 

and their health and environmental impacts; noise; safety (e.g., visibility of 

cooling tower plumes, icing); electric grid reliability, and facility reliability.

The permit application will provide the Director with information about options 

for entrainment reductions at the site and other possible avenues for addressing any 

adverse effects from entrainment. The purpose of the ECSentrainment study and other

permit application materials is to assist the Director in better understanding the effect of 

entrainment on species in the waterbody from which cooling water is withdrawn. More 

specifically, the ECSentrainment study will identify species that might be entrained, and 

estimate their baseline entrainment rates given current entrainment controls. Moreover, 

the ECSentrainment study will include information about the aquatic ecosystem effects of 
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entrainment of species, species that might be susceptible to thermal effects (including 

thermal barriers), and any threatened and endangered species whose range of habitat 

includes waters where the facility’s intake is located. An understanding of the potential 

ecosystem consequences of entrainment for species will help inform Director decisions 

about additional information required in the permit application, or permit requirements 

for any possible additional technologies and management practices. EPA will endeavor to 

identify high-quality examples of ECSsentrainment studies as they are completed, and 

post them to its website for this rule as a resource for ECSstudy preparation. 

EPA’s benefits estimates were based on an extrapolation of available literature on 

impingement and entrainment studies; the specific entrainment characterization 

studyEntrainment Characterization Study prepared by a facility could lead to a different 

estimate of impingement and entrainment for that facility relative to its share of EPA’s 

estimate in the analysis supporting this rule and in the record. 

Following the Director’s review of this information, the Director must determine 

what BTA entrainment requirement to propose and explain in writing the basis for the 

draft permit. The draft permit will then be available for comment from the interested 

public under the Director’s normal permitting process. 

2. Site-Specific Consideration of Cost and Benefits 

In establishing performance standards for entrainment controlsrequirements under 

section 316(b) of the CWA, the Supreme Court in Entergy made clear that one factor that 

EPA may, but is not required, to, consider is the costs and benefits associated with 

various control options. That is, in setting standards, EPA may consider the benefits 
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derived from reductions in the adverse environmental impacts associated with cooling 

water intake structures and the costs of achieving the reductions. As previously 

explained, following E.O. 13563, EPA has determined that the benefits of the final rule 

justify its costs. In addition, EPA has explained (in Section II.C above) why consideration 

of quantitative and qualitative social costs and benefits may be appropriate in the sitespecific determinations when establishing entrainment controls. 

In the site-specific proceeding, the Director maymust consider, among other 

factors, monetized, 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 be able to reject otherwise available entrainment 

controls if the costs of the controls are not justified by their associated benefits (taking 

into account bothmonetized, quantified, and non-quantifiedqualitative benefits), and the 

other factors discussed in the final rule. 

In making the site-specific entrainment BTA requirements determination, the final 

rule requires that the Director consider the information submitted under § 122.21(r) with 

the section 316(b) permit application. Further, in the case of the larger withdrawing 

cooling water intake structures (125 mgd AIF or greater), the rule will requirerequires

submission of additional information including, studies on entrainment at the facility, the 

costs and feasibility of control options, and information on the monetized and 

nonmonetized benefits of entrainment controls. In evaluating benefits, the Director 

should not ignore benefits that cannot be monetized or quantified or consider only the 

impingement and entrainment reductions that can be counted. To result in appropriate 
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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 nonlocally 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. and should not 

be included at least qualitatively in any assessment. The rule does not require the 

Director to require a facility owner or operator to conduct or submit a willingness-to-pay 

survey to assess benefits. Further, the rule does not limit the Director’s discretion to 

consider non-water quality impacts in determining whether further entrainment measures 

are justified. When some benefits are not monetized, the requirement to consider costs 

and benefits in today’s rule does not mean the Director should base decisions solely on 

the monetized benefits and costs, ignoring the non-monetized benefits. Instead, the 

Director should consider the costs and what the magnitude of the non-monetized benefits 

would have to be in order to justify the costs. 

A nationalAn aggregate evaluation of benefits (no matter howeven if accurate) 

would fail tonot 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 impingement and entrainment 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 
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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 water bodies. 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’s difficult to ascertain which facility hasecological environment faces the 

greater adverse environmental impact from a similar cooling water intake. 

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. 

The Director must then explain the basis for rejecting an available technology not 

selected for entrainment control in light of the submissions after consideration of the 

three of the four factors that supported EPA’s determination not to establish a uniform 
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national entrainment standard based on closed-cycle cooling. EPA expects thatThe 

Director also must base the Director’s decisiondetermination about BTA controls will 

also reflecton the number and types of organisms entrained, including Federally-listed, 

threatened and endangered species and designated critical habitat (e.g., prey base) as well 

as consideration of the site-specific social costs and benefits (monetized and 

nonmonetized) of the various control technologies considered for the facilities. 

As noted, the Director may reject an otherwise available entrainment technology 

as the BTA requirement (or not require any additional BTA controls) if the social costs of 

the controls are not justified by the social benefits. (monetized and nonmonetized). EPA 

decided to adopt this approach in determining site-specific entrainment controls because 

it is permissible under Entergy, under E.O. 13563, and consistent with the more than 30-

year history of section 316(b) permitting decisions and E.O. 13563. 

This history illustrates the role that cost/benefit considerations have played. As 

early as 1977, EPA issuedin a permitting decision and a General Counsel opinion that

explained that, while section 316(b) does not require a formal cost-benefit analysis, the 

relationship of costs and benefits may be considered in 316(b) decision making. In re 

Pub. Serv. Co. of N.H. (Seabrook Station, Units 1 and 2), No. 76-7, 1977 WL 22370 

(June 10, 1977), remanded on other grounds, 572 F.2d 872 (1st Cir. 1978); accord In re 

Central Hudson Gas & Elec. Corp., Op. EPA Gen. Counsel, NPDES No. 63, 1977 WL 

28250, at *8 (July 29, 1977). In the more than 30 years since, EPA and stateState

permitting authorities have considered the relationship between costs and benefits to 

some extent in making individual permitting decisions. See, for example, In re Pub. Serv. 
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Co. of N.H. (Seabrook Station, Units 1 and 2), No. 76-7, 1978 WL 21140 (E.P.A. Aug. 4, 

1978), aff’d, Seacoast Anti-Pollution League v. Costle, 597 F.3d 306, 311 (1st Cir. 

1979). 

Because E.O. 13563 directs agencies to propose and adopt rules only upon a 

reasoned determination that the benefits justify the costs, EPA is allowing for this same 

consideration into be applied at the national BTA standard under Section 316(b) of the 

Clean Water Act.permit level. This approach is consistent with the historical application 

of section 316(b) approach EPA has traditionally followedrequirements and will allow 

for a full assessment in permit decisions of both qualitative and quantitative benefits and 

costs. As designed, EPA’s requirement for the establishment of site-specific BTA 

entrainment requirements strikes an appropriate balance between environmental 

improvements and costs, allowing the Director to consider all the relevant factors on a 

site-specific basis and determine BTA on the basis of those factors. 

After considering the factors relevant to a site, the Director must establish 

appropriate entrainment controls at those facilities. The Director must review available 

control technology and may reject otherwise available entrainment controls as BTA if the 

social costs of the controls are not justified by their social benefits (taking into account 

both quantified and non-quantified benefits) or if the Director concludes that there are 

other unacceptably adverse factors that cannot be mitigated. The rule also provides that 

the Director may not reject an otherwise available technology as a basis for entrainment 

requirements based on a comparison of social costs and social benefits if the facility 

failed to provide the required information under § 122.21(r) related to benefits. As 
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designed, EPA’s national BTA standard for establishing site-specific BTA entrainment 

requirements strikes an appropriate balance between environmental improvements and 

costs by selectively requiring closed-cycle cooling or other entrainment technologies at 

some facilities, without requiring the same technologies at all facilities. 

3. Potential Cost for Site-Specific Entrainment Controls 

For the proposed rule, EPA prepared a brief economic analysis ofanalyzed

possible additional costs associated with reductions in entrainment mortality that might 

result from the Directors’ determinations of site-specific BATBTA requirements. 

Because this process will play out over a number of years as Directors consider water 

bodywaterbody-specific data, local impacts, and public comment, and weigh land 

availability, air quality impacts, and remaining useful life, those estimates of the costs of 

site-specific determinations wereare highly speculative. EPA is not costingpresenting 

specific cost estimates today for prospective entrainment requirements because we do not 

have in hand the robust data that will be generated for individual site-specific settings as 

part of the process that isrequired under the national BTA standard for entrainment. 

Without that refined information on a site-specific basis, EPA has no basis for 

prejudgingability to predict Director decision-making and therefore, the Agency is not 

estimating costs associated with the ultimate entrainment requirements. Similarly and for 

the same reasons, EPA did not estimate costs associated with requirements at § 

125.94(g), 125.94(c)(8) or 125.94(c)(9).

EPA estimates that the best performingmost effective technology for reducing 

entrainment, closed-cycle cooling, is not available to at least one quarter of all facilities 
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because of geographic constraints, air permitting restrictions in a nonattainment area and 

remaining useful life. of the facility. EPA has very limited information on which facilities 

these are, despite the certainty that thethese availability concerns are real and significant. 

In addition, EPA does not have in hand the site-specific data that will be generated as a 

result of today’s rule. If EPA had this data, it would be possible to estimate the costs and 

benefits ultimately associated with the Directors’ site-specific determinations under the 

national BTA standard for entrainment. The hypothetical costs generated at proposal 

were reported in an attempt to signal that EPA neither expects that zero facilities would 

be subject to closed-cycle cooling as a result of the site-specific BTA process for 

entrainment, nor that the oldall facilities at which these technologies are feasible would 

be subject to closed-cycle cooling requirements. Without the site-specific information, 

there is significant uncertainty around any estimates EPA could generate of these costs 

(including those reported at proposal).) and benefits. 

 

VII. Response to Major Comments on the Proposed Rule and Notices of Data 

Availability (NODAs) 

Over 1,100 organizations and individuals submitted comments on a range of 

issues in the proposed rule, including over an additional 62,000 letters from individuals 

associated with mass letter writing campaigns. An additional nearly 250 comments were 

received on the two NODAs. Responses to all comments, including those summarized 

here, are in the Response to Comments document in the official public docket. (see DCN 

12-0004). To facilitate a more comprehensive response and to simplify the task of 
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discussing EPA’s rationale for promulgating the final rule, EPA is responding to these 

public comments in essay form. Each topic area discussed in the comment letters has 

been addressed in one of the comprehensive essay responses. The major comments 

received and EPA’s responses are summarized in this section. 

A. Scope and Applicability 

1. Source of Water – Impoundments 

Many commenters expressed concern that the proposed rules do not adequately 

address the unique water bodies resulting from the many man-made reservoirs 

specifically designed and constructed as cooling water impoundments (definedreferred to

as cooling ponds in the proposed rule). Commenters expressed confusion regarding the 

applicability of the proposed regulations to intakes onbecause impoundments have both 

intakes from the impoundments and the intakes that supply water to the 

pondsimpoundment. Many requested that EPA clarify that man-made impoundments, 

built to supply water for power plants, do not constitute water of the United States for 

purposes of implementing the rule or that they should be classified as meeting the 

definition of closed-cycle cooling. 

Response: As discussed in Section I, facilities that withdraw cooling water from 

impoundments that are waters of the United States and that meet the other criteria for 

coverage (including the requirement that the facility has or will be required to obtain an 

NPDES permit) are subject to today’s rule.otherwise meet the criteria for coverage 

(including the requirement that the facility has or will be required to obtain an NPDES 

permit) are subject to today’s rule. Revisions to the definition of waters of the U.S. are 
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outside the scope of this rulemaking. However, today’s regulatory definition of closedcycle recirculating systems specifies that such a system may include impoundments of 

waters of the U.S. where the impoundment was constructed prior to today’s final rule. To 

meet the rule definition for closed-cycle recirculating system, this impoundment must 

have been lawfully created for the purpose of serving as part of the cooling water system 

as documented in the project purpose statement for the Clean Water Act section 404 

permit obtained to construct the impoundment. In the case of an impoundment whose 

construction pre-dates the CWA requirement to obtain a section 404 permit, EPA expects 

documentation of the project’s purpose to be demonstrated to the satisfaction of the 

Director. This documentation could be some other license or permit obtained to lawfully 

construct the impoundment for the purposes of a cooling water system, or other such 

evidence as the Director finds necessary. 

The definition of closed-cycle recirculating system at § 125.92(c)(1) of today’s 

rule also specifies that impoundments that are not waters of the United States but 

withdraw make-up water from waters of the U.S. meet the definition of a closed-cycle 

recirculating system, if make-up withdrawals have been minimized. These 

impoundments are constructed in uplands, and are not required to obtain a 404 permit. 

Thus, these impoundments do not need to provide documentation of the project’s 

purpose. 

2. New Units 

In the proposal, EPA defined new units as newly built units added to increase 

capacity at the facility. The definition did not include any rebuilt, repowered or 
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replacement unit, including any units where the generation capacity of the new unit is 

equal to or greater than the unit it replaces. Many industry stakeholders agreed that the 

definition of new units should not include repowered existing units. Others thought that 

new units should be treated similarly to existing units with entrainment standards applied 

on a site-specific basis and that the nine proposed factors should also be applied to 

entrainment decisions for new units. Environmental organizations argued that EPA 

should set a deadline by which all existing facilities must comply with the new unit 

standards and that EPA’s exclusion of repowered/rebuilt plantsfacilities created a 

loophole through which existing facilities could perpetually operate as an existing unit, 

even after replacing all of the generating equipment. Many of the comments had several 

elements in common: 

• Requirements should be flexible enough to address sites where meeting the 

requirements is not technically feasible (e.g., limited land availability). 

• EPA needs to provide greater clarity regarding how new unit standards apply to 

manufacturing facilities. 

• The DIF is a more appropriate parameter for determining compliance because 

AIF cannot be determined until after the system is built, and baseline AIF would 

require assumptions about as-yet undetermined operational factors. 

• It is unclear how the new unit requirements will be applied to manufacturing 

units, and the 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. 
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• Some commenters have noted that the new unit provisions are a departure from 

previous determinations and are unclear. They argue that they have not had 

adequate opportunity to comment on this issue and request EPA re-propose new 

unit requirements if it wants to continue with this initiative. 

Response: EPA's definition of a "new unit" for the final rule can be found at § 

125.92.(u). New units include "any additional unit that is includes the addition of a standalone unit where a new condenser and turbine are built and that that is constructed at an 

existing facility. For purposes of this subpart,The rule definition makes it clear that the 

new unit may be for the same general industrial activity as the existing facility. Because 

the requirements are much like the Phase I requirements for new unit includes any 

rebuilt, repowered or replacement unit where the turbine and condenser have been 

replaced as partfacilities the costs for installing controls at new units are similar to the 

costs imposed on new facilities. The cooling water withdraws made by the rest of the 

rebuilding, repowering or replacing, except in the case of high energy efficiency units." 

existing facility are subject to the requirements at 40 CFR 125.94(c) and (d).

With respect to entrainment, the final rule requires that new units achieve flows 

commensurate with that of a closed-cycle recirculating system. With respect to 

entrainment, the final rule requires new units comply with the same BTA impingement 

mortality standards as existing facilities. With respect to impingement mortality and 

entrainment, the final rule requires, at § 125.94(e)(1), that new units achieve flows 

commensurate with that of a closed-cycle recirculating system. As with the new facility 

Phase I rule, the new unit may choose to meet an alternative requirement at 40 CFR 
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125.94 (e)(2) and demonstrate to the Director that the technologies and operational 

measures employed will reduce the level of adverse environmental impact from any 

cooling water intake structure used to supply cooling water to the new unit to a 

comparable level to that which would be achieved upon implementing closed-cycle 

recirculating for that new unit. This includes a demonstration showing that the 

entrainment reduction is equivalent to 90 percent or greater of the reduction that could be 

achieved through implementing a closed-cycle recirculating system. This demonstration 

must also include a showing that the impacts to fish and shellfish, including important 

forage and predator species, within the watershed will be comparable to those which 

would result if the facility were to implement a closed-cycle recirculating system. 

Facilities may choose to install a closed-cycle recirculating system, and EPA has 

observed that many new units are selecting closed-cycle recirculating systems on their 

own, particularly for combined cycle and natural gas for reasons unrelated to 316(b) 

(such as water availability). In these cases, benefits related to reductions in IM&E would 

be expected to occur. 

Finally, for new units at existing facilities, the Director may establish alternative 

requirements if the data specific to the facility indicate that compliance with the 

requirements of paragraphs (e)(1) or (2) of § 125.94 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 
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entrainment, or significant adverse impacts on local energy markets. This provision is 

identical to that provided in the Phase I new facility rule. 

B. Proposed Amendments Related to Phase I Rule 

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 

cooling water intake structure technology, where affected species are not species of 

concern in man-made lakes, and to reduce the cost of meeting 316(b) requirements (i.e., 

offset losses). 

Response: The Second Circuit found that EPA exceeded its authority by allowing 

facilities subject to CWA section 316(b) to comply with section 316(b) through 

restoration measures and, thus, EPA has deleted these provisions from the regulations at 

§§ 125.84 and 125.86 to make the rule consistent with the court decisions. 

C. Environmental Impact Associated with Cooling Water Intake Structures 

Many commenters expressed concern that limited scientific evidence exists that 

measureable aquatic population or community effects occur as a result of cooling water 

withdrawals and that impingement mortality and entrainment mortality requirements 

should not apply unless adverse environmental impacts are demonstrated. They also 

noted that not all environmental impacts are adverse. For example, removal of invasive 

species or quickly reproducing species might not be harmful. 

Response: EPA disagrees. The evidence shows that the total number of aquatic 

organisms lost annually is 2.2 billion.in the hundreds of billions, or is 1.9 billion on an 
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age-one equivalent basis. Additional data provided in comments shows aquatic organisms 

are lost through impingement and entrainment by all types of cooling water intake 

structures. The data demonstrates that the effects of cooling water intake structures on the 

aquatic environment are significant and widespread. In addition, there is documented 

evidence of population level effects of cooling water intakes for certain species in certain 

instances. See, for example, 69 FR 41587 (, July 9, 2004) for a discussion from the 2004 

Phase II rule. Also, Bayshore, Indian River and Indian Point are discussed in the BA for 

the final rule.

D. EPA’s Approach to BTA 

1. Relationship of Costs and Benefits 

Many commenters expressed concern that the proposed rule’s costs significantly 

outweigh the benefits and that studies, technology modifications, monitoring, and 

reporting should not be required if costs exceed benefits. 

Response: 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 the 

nonuse benefits transfer was based on a species in two coastal regionsthat represents less 

than one percent of adverse environmental impacts. With respect to entrainment, the rule 

authorizes the Director to consider costs versus benefits on a site-specific basis. With 
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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 whose efficacy is well supported in EPA’s record. 

2. Site-Specific approach 

Many commenters agreed with EPA’s site-specific approach for entrainment 

mortality requirements but argued that the same approach should also be applied to 

impingement mortality requirements. State agencies and environment organizations are 

concerned that the site-specific entrainment determinations will create additional 

administrative burdens on already overextended permitting authorities which could 

exacerbate permit backlogs. 

Response: EPA does not agree that impingement mortality is best addressed by 

the same approach adopted for entrainment. This is because EPA has been able to 

identify low-cost technologies that are available, feasible and demonstrated for 

impingement mortality nationally. EPA has not been able to identify an available, 

feasible and demonstrated technology nationally for entrainment, and therefore has 

adopted as its national BTA entrainment standard a structured process for determining on 

a site-specific basis what entrainment controls are the best technology available at a 

particular facility. EPA agrees that site-specific entrainment has potential to create 

additional burdens for states, but EPA has tried to limit this burden by simplifying its 

information collection requirements from those at proposal. EPA has streamlined the 

information collection requirements so that information necessary for the Director to 

make a BTA determination is submitted by the permittee in the permit application early 
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in the process, thus minimizing the number of transactions between permittee and the 

Director. 

E. BTA Performance Standards 

1. Impingement Standards 

EPA received a substantial number of comments on how the final rule should 

address impingement mortality. EPA based its proposed an impingement mortality 

standards standard based on the performance of modified traveling screens with fish 

handling and return that required achievement of a numeric IM performance standard. As 

an alternative EPA proposed that a facility could demonstrate that either the design intake 

velocity or the actual intake velocity at its operation was less than 0.5 fps. Most of the 

commenters, including members of the U.S. Congress, state and local elected officials, 

and industry stakeholders, requested additional flexibility in complying with the 

impingement mortality standards. While the proposal would not specifically require the 

use of modified traveling screens with a fish handling and return system to meet the 

impingement mortality limitsstandards, some commenters interpreted the proposed rule 

as requiring this. EPA proposed impingement mortality limitsstandards that were 

expressed as a monthly average and an annuala 12-month average. EPA recognizes, 

however, that some regulated entities might find a technology-based compliance option, 

rather than a performance-based approach, more attractive. Such an approach, 

particularly the specification of pre-approved technologies, could offer higher regulatory 

certainty, easier demonstration of compliance, and might offer a less expensive 

alternative because of reduced monitoring requirements associated with pre-approved 
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technologies. Some commenters viewed the proposed impingement mortality 

limitstandard as overoverly stringent and requested that EPA establish alternative 

impingement mortality standards, including site-specific impingement mortality 

requirements similar to those proposed for entrainment. Other commenters provided data 

pertaining to the performance of technologies, including modified traveling screens used 

as the basis for the impingement mortality limit.performance standard. Several industry 

stakeholders stated that, despite EPA’s best intentions, the proposed rule applied a onesize-fits-all approach for impingement mortality. While all the suggested changes to the 

proposal seek to provide additional flexibility through a variety of approaches, most of 

the comments had several elements in common: 

• Commenters suggested definingDefining modified traveling screens as a preapproved technology or otherwise streamlining the NPDES process for facilities 

using the candidate technology on which BTA is based. Thus, EPA would 

designate certain technologies or certain conditions as complying with the 

impingement requirement. 

• Providing a mechanism to identify other technologies that perform comparably to 

modified traveling screens. 

• Modifying the proposal so that facilities that have already reduced the rate of 

impingement could obtain credit toward the impingement mortality standard. 

• Developing a more tailored approach to protecting shellfish. 

• Creating alternatives for facilities with very low (de minimis) impingement levels 

or mortality rates. 
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• Providing additional clarity on species of concern as it pertains to demonstrating 

compliance with the numeric impingement mortality performance standard. 

• Reevaluating the impingement mortality limitsnumerical performance standards. 

In addition, as noted above, EPA also received a number of comments suggesting 

that it adopt a site-specific approach to reducing impingement mortality similar to the 

proposed approach for addressing entrainment, rather than uniform national requirements 

for impingement mortality and a site-specific approach for entrainment only. 

Many commenters expressed concern that the entrapment requirements were not 

well defined and would require costly technologies that are not considered in EPA’s cost 

estimates and could be difficult to comply with, particularly where cooling systems 

employ impoundments or basins downstream of the initial intake structure. 

Response: See the earlier discussion at Section VI.C.1 concerning how EPA 

determined the numeric impingement mortality performance standard. Additionally, see 

theearlier discussion at Section VI.E.1 for an explanation of how EPA revised the 

impingement mortality standard to provide seven alternatives for compliance. 

EPA agrees that specific entrapment requirements are not necessary and 

requirements for facilities to deploy technologies to avoid entrapment have been deleted 

from the final rule. However, a facility that entraps fish must count the entrapped 

organisms as impingement mortality. 

2. Entrainment Standards 

A substantial number of commenters supported EPA’s site-specific approach for 

entrainment standards. Suggested revisions to the approach included the following: 
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• EPA should recognize the value of water bodywaterbody-based requirements, 

including withdrawals on lakes/reservoirs and less than 5 percent of rivers as not 

requiring entrainment mortality. 

• Units with a low capacity utilization of less than 15 percent should be exempt 

from entrainment mortality. 

• Facilities with AIF of less than 125 mgd should be presumed as entrainment 

mortality compliant. 

• EPA should consider entrainment survival. 

Response: With respect to water bodywaterbody-based requirements and capacity 

utilization thresholds, EPA disagrees with commenters suggestions. There is no 

fundamental difference in technological performance based on waterbody so there is no 

need to subcategorize based on waterbody. EPA found that low CUR facilities are 

generally peaking plants that operate at full capacity for a few months. If that period 

ofportions 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. 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, simply being a low CUR unit does not 

imply no adverse environmental impacts. Instead, EPA found that low CUR should be 

looked at more closely on an individual unit basis. EPA has included a provision in the 

final rule that states where a generating unit has an annual average capacity utilization 

rate of less than 8 percent averaged over a 24-month block contiguous period, the owner 
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or operator may request that the Director establish less stringent standards for IM. With 

respect to facilities below 125 AIF being considered entrainment compliant, EPA 

disagrees with the comment since any facility at any flow may have an adverse 

environmental impact. With regard to entrainment survival, EPA does allow for 

consideration of entrainment survival. The monitoring requirements for entrainment for 

new units at § 125.96(d)(23) 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 of concern is less than 100 

percent. 

3. Closed-Cycle Cooling 

Both industrial stakeholders and many state agencies endorsed an approach that 

deems facilities with closed-cycle cooling to be in compliance with the BTA 

impingement mortality standard, and eligible for reduced monitoring and reporting 

requirements. Most industrial stakeholders agreed with the EPA decision that closedcycle cooling should not be imposed as a national BTA standard. They argue that 

although closed-cycle cooling might be available and achievable at many facilities, 

requiring closed-cycle cooling nationally has numerous drawbacks including the 

following: 

• Requirements for closed-cycle flow reduction do not take into consideration ofthe

site-specific limitations at some facilities (e.g., blowdown water quality, scale, 

fouling problems). 
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• Cooling towers would result in significant adverse impacts from fine particulates, 

carbon dioxide emissions, evaporative water loss, and other issues. 

Commenters expressed concern that the proposed definition of a closed-cycle 

recirculating system is far more restrictive than the definition used in the Phase I rule. It 

includes only systems that withdraw make-up flow intermittently, are designed to operate 

above minimum COC, reduce flow by a specified percentage (depending on whether salt 

ofor fresh water), and did not include impoundments that are waters of the United States. 

Some commenters stated that while they might have been effectively operating as closedcycle units for many years, they have concerns with their ability to comply with the 

definition in the proposal, particularly with respect to the specified COC. 

Response: EPA agrees that facilities employing a closed-cycle recirculating 

system for entrainment should also be deemed in compliance with the impingement 

mortality standard, as long as the system is properly operated. While a closed-cycle 

recirculating system is the best performingmost effective technology, however for 

reducing entrainment, EPA has not established BTA based on closed-cycle cooling 

because the technology doesEPA concluded it was not represent BTA, for the reasons 

specified in Section VI. Regarding the definition of closed-cycle cooling, EPA identified 

two parameters that demonstrate proper operation: flow reduction and cycles of 

concentration. To provide flexibility, EPA has removed the numeric levels of the metrics 

as threshold, while retaining the minimized makeup flows aspect of the definition. 

Therefore while the definition in this final rule does not establish fixed 

limitsrequirements in terms of COC and comparable percentage flow reduction to qualify 
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as a closed-cycle recirculating system. Rather, the rule provides that a closed-cycle 

recirculating system “generally” will achieve the specified benchmarks that characterize a 

properly operating closed-cycle cooling system. EPA further recognizes that certain 

unavoidable circumstances could exist where the specified COC or percent reduction 

values might not be achievable. Such site-specific 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 the source 

water quality could lead to unavoidable problems concerning scale formation, solids 

buildup, corrosion, or media fouling. If a facility can demonstrate that these occurrences 

are unavoidable, under the definition in the final rule, the Director may determine that 

such a facility is a closed-cycle recirculating system, taking into account the site-specific 

circumstances. In addition, EPA has explained how the conditions added to the existing 

facilities definition do not in effect make it more stringent than the Phase I definition of 

closed-cycle recirculating systems. The auxiliary electricity a facility uses to run the fans 

in a closed-cycle system is electricity the facility can’t sell. The opportunity cost to the 

facility of using that electricity to run the fans is the forgone revenue they would have 

been able to earn if they had run their cooling water system in once-through mode. The 

forgone revenue provides the incentive for a facility to run its closed-cycle system in 

once-through mode, rather than in closed-cycle mode. Thus, EPA adjusted the definition 

of a closed-cycle recirculating system to be appropriate for retrofit situations. 
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F. Implementation 

Many commenters expressed concern that the compliance timeline for 

impingement mortality and entrainment requirements should be synchronized to prevent 

a facility from having to install technology to comply with impingement mortality 

requirements and then later be required to install entrainment mortality technology. 

Response: To address this concern, EPA revised the impingement mortality 

compliance requirements to provide that after issuance of a final permit establishing the 

entrainment requirements under § 125.94 (d), the owner or operator of an existing facility 

must comply with the impingement mortality standard in paragraph § 125.94(c) as soon 

as possiblepracticable. When the Director establishes a compliance schedule under § 

125.94(d), the schedule must provide for compliance as soon as possiblepracticable. 

Thus, EPA has synchronized decision making about technology requirements, avoiding 

situations where investments in IM controls would later be rendered obsolete by 

entrainment control requirements. 

G. Costs 

1. Impingement Mortality Technology Costs 

Commenters expressed concern about the approach for technology assignments 

used to estimate compliance with the impingement mortality standards and generally 

asserted that costs were underestimated. These concerns included the following: 

• The EPA incorrectly assumed traveling screens were an available technology at 

most facilities. 

• EPA underestimated the costs of modified traveling screens. 
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• EPA underestimated the difficulty and costs of installing fish returns. 

Response: EPA disagrees that traveling screens are not an available technology at 

most facilities; survey data provided by industry shows that 93% percent of generators 

and 73% percent of manufacturers already have screens. EPA agrees that some facilities 

may not be able to readily upgrade their screens to modified traveling screens with fish 

return, but that the vast majority can. 

EPA has updated the estimated costs of the rule to reflect the difficulty of 

installing fish return and adjusted the cost of modified traveling screens to reflect most 

recently available vendor data. Specifically, EPA reviewed the cost methodology and 

made a number of revisions including the following: 

• EPA revised the technology assignment such that only those model intakes that 

have existing traveling screens are assigned modified traveling screen costs. 

• EPA increased the estimated capital costs for modified traveling screens by 

20 percent. 

• EPA increased the estimated capital costs of fish returns and provided for an 

additional increase for facilities whose intakes would be difficult to install fish 

returns. 

For further discussion, see Section IX and the TDD (Chapter 8). 

2. Entrainment Mortality Technology Costs 

Industrial stakeholder commenters argued that closed-cycle cooling costs are 

underestimated and the cost analysis fails to include any costs for entrainment 

requirements. Riverkeeper argued that the EPA closed-cycle costs are overestimated. 
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Response: For both the proposal and this final rule, EPA revised the methodology 

for estimating closed-cycle costs from what was used for Phase II and Phase III. EPA’s 

revised methodology is based on the cost methodology provided by the Electric Power 

Research Institute (EPRI). EPRI based its cost methodology on over 50 actual and 

planned closed-cycle cooling system retrofits and EPA concluded that these cost 

estimates better reflect actual costs. EPRI has updated their closed-cycle cost 

methodology since EPA adoption of the earlier version and provided an estimate of 

closed-cycle costs for generators with a design flow above 50 mgd (See DCN 12-

XXX6807). A comparison between the EPRI estimates and comparable EPA estimates 

indicate that the EPA capital and downtime costs are somewhat lower than the EPRI 

estimates, while the EPA energy penalty costs are higher. (See DCN 12-XXX Memo 

comparing EPRI and EPA costs6656.) While Riverkeeper cites actual costs from retrofit 

projects completed in 1998 and 2002 to support the argument that EPA’s capital costs are 

overestimated, EPA has identified more recent closed-cycle retrofits where the capital 

costs were much higher than the EPA average, suggesting that the costs used by EPA in 

the final rule are representative of the range of costs that may occur nationwide. (See 

DCN 12-XXX Memo comparing EPRI and EPA costs6656.) Thus EPA considers its 

closed-cycle costs to reasonably reflect actual costs. 

EPA also received estimated costs for closed-cycle retrofits at small, medium, and 

large manufacturing cooling systems from the American Chemical Council (ACC). A 

comparison of these costs to comparable EPA estimates indicated that for larger systems 

the costs are mostly in agreement but that for smaller systems (e.g., 5,000 gpm), the EPA 
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cost estimates are lower. EPA’s acknowledges its methodology uses a linear approach 

and does not fully account for the increased costs associated with the diseconomies of 

scale at the lower end of the spectrum of system sizes. 

Under EPA’s selected option, compliance for entrainment reduction requirements 

is established on a site-specific basis. Because no particular result is prescribed under this 

approach, it is difficult to ascribe compliance costs for this aspect of the rule without the 

site-specific information that will be generated as a result of the national BTA standard 

for entrainment decision-making established by today’s rule. For Proposal Options 2 and 

3 where closed-cycle cooling would be required, EPA did estimate costs for closed-cycle 

cooling. EPA has not estimated what site-specific determinations will be made as part of 

the analysis. 

H. Monitoring and Reporting

1. Velocity Monitoring 

Many commenters explained that it would be difficult to directly measure 

through-screen velocity for screen technology and agreed with the suggestion in the 

NODA that EPA should allow for calculation of through-screen velocity. Also, many 

were concerned that a velocity limit based on minimum water levels would be difficult to 

comply with. Of concern are extreme conditions that are beyond the facility’s control 

(e.g., low water due to drought). 

Response: 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 standardsIM compliance alternatives by either calculation 
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or direct measurement. Compliance will be demonstrated through monitoring and 

reporting of actual or calculated intake velocities. Short-term exceedances of the velocity 

standard may be permissible for brief periods, with Director approval, 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 limit is not exceeded during minimum ambient source water 

surface elevations, as can be anticipated through best professional judgementjudgment

using hydrological data. 

2. Impingement Mortality Monitoring 

EPA received many comments concerning impingement mortality monitoring. 

Issues regarding impingement monitoring included the following: 

• Many commenters expressed concern that the impingement mortality standard is 

unclear as to what species the impingement mortality requirements apply. 

• Intakes with low impingement would have difficulty calculating impingement 

mortality. 

• Monitoring requirements for impingement mortality are excessive, especially 

given the physical and biological challenges of appropriate sampling. 

• Monitoring requirements should be eliminated for properly installed/operated preapproved technologies. 

• Impingement “selects” impaired organisms, resulting in bias. 

Response: EPA has addressed concerns regarding monitoring in the final rule. For 

example, there is no biological compliance monitoring for pre-approved and approvable 
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technologiesstreamlined compliance alternatives in § 125.94 (c)(1) through (56) of 

today’s rule beyond that required for the permit application, and monitoring may be 

greatly reduced for other facilities. EPA recognizes that biological monitoring can be 

expensive, which factored into EPA significantly reducing those requirements. With 

respect to intakes with low impingement having difficulty calculating impingement 

mortality, facilities can demonstrate under § 125.94(c)(6) that the rate of impingement is 

reduced due to intake location or other technologies or factors. Further, under § 

125.94(c)(1211) a facility can demonstrate to the Director that there is a de minimis rate 

of impingement such that no additional controls are warranted. 

3. Reporting Requirements 

Comments concerning reporting requirements included the following: 

• Commenters argue that permit application deadlines are unreasonable, especially 

given the limited number of consultants available and that EPA overestimates the 

number of facilities that have completed these studies. 

• Peer review requirements are overoverly burdensome. 

• ApplicationPermit application requirements are burdensome and EPA should 

revise the proposed rules to remove, limit, or streamline the numbers and types of 

data, studies, and reports required. ApplicationPermit application requirements 

should be reduced for smaller facilities with intake flow in the 2–125 mgd range. 

• The proposed rule requires the § 122.21(r) permit application materials for each 

permit cycle, regardless of whether the facility has been modified. After the initial 

assessment of BTA in the first permit cycle under the new rule, the permittee 
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should not be required to do additional studies and submit further documentation 

unless there is a significant change in the facility’s cooling system. 

Response: EPA notes that facilities have several flexibilities to address the first 

point, including: (1) if a permit is issued prior to December 31, 2016,[INSERT date 45 

months after effective date of final rule], the Director can delay submission 

requirements until such time that the facility can complete them and (2) in permit terms 

subsequent to the first permit issued under today’s rule, the Director can waive some or 

all of the studies. With respect to peer review, EPA disagrees that peer review is overly 

burdensome. How to undertake a peer review is a widely known, generally following a 

well-established process. EPA notes that peer review is a normal part of Agency 

activities, and that commenters generally favor the application of peer review to 

environmental data and analyses. With respect to the burden of the permit application 

process and subsequent permit cycles, EPA has reduced the permit application 

requirements for the final rule and streamlined biological data collection to two years of 

data collected as part of the permit application (with the exception of the few facilities 

expected to comply with the impingement mortality standard under the alternative at § 

125.94(c)(7)). In addition, entrainment studies are not prescribed for facilities below 125 

mgd, although the Director may require the facility to provide information beyond the 

basic permit application information. Also, the Director can waive study requirements in 

permit terms subsequent to the first permit issued under today’s rule. 
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I. EPA Legal Authority 

CommentersI. Endangered Species Act 

Some commenters argued that it is inappropriate to automatically to treat 

endangered and threatenedT&E species in a special category and provide for special 

consideration for them under the rule. TheyThese commenters asserted that EPA has no 

basis for incorporating ESA (Endangered Species Act) requirements into the rule and 

addressing ESA species under the NPDES program; they argued that the ESA operates 

independently. Other commenters noted EPA’sargued that EPA has an obligation under 

the ESA to consult with the Services if cooling water intake structures are likely to affect 

threatened or endangered species. 

Response: With regard to the Endangered Species Act, EPA has addressed 

threatened and endangeredT&E species and critical habitat in this rule to the extent 

necessary to ensure that this action is consistent with both the Endangered Species Act 

and CWA section 316(b). UnderSection 7 of the Endangered Species Act, EPA is 

required to ensure states that “each Federal agency shall, in consultation with and with 

the assistance of the Secretaries of the Interior and Commerce,[the services] insure that 

any action authorized, funded, or carried out by EPA[the agency]... is not likely to 

jeopardize the continued existence of any listedthreatened or endangered species or result 

in the destruction or adverse modification of habitat that has been [designated as critical

for the species.] habitat.” Under CWA section 316(b), EPA must ensurefacilities subject 

to NPDES permitting that regulatedhave cooling water intake structures are subject to 

BTA to minimize adverse environmental impacts. The final rule requires NPDES 316(b) 
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permittees to characterizeidentify all Federally-listed threatened orand endangered 

species and/or designated critical habitat that are or may be present in the source water, 

characterize any entrainment ofaction area. The Director may reject an otherwise 

available technology as a basis for entrainment requirements if the Director determines 

there are unacceptable adverse impacts including impingement, entrainment, or other 

adverse effects to Federally-listed threatened or endangered species, and consider any 

benefits to threatened or endangered species in establishing any site-specific entrainment 

requirements or designated critical habitat. EPA consulted with the Services under the 

ESA regarding this rule, and a summary of the requirements related to threatened or 

endangered species is discussed in Section VIII.K of this preamble. 

VIII. Implementation 

The following sections describe how the Agency expects the final rule 

requirements to be implemented. The requirements of today’s final rule will be applied to 

facilities through NPDES permits issued by EPA or authorized States under CWA section 

402. A facility may generally choose to demonstrate compliance with the final rule by 

demonstrating compliance for the entire facility, or by demonstrating compliance for each 

individual cooling water intake structure. For example, a facility with two intakes could 

demonstrate flow reduction commensurate with an existing closed-cycle recirculating 

system for the first intake, and demonstrate the intake velocity at the screen face is less 

than 0.5 feet per second at the second intake. Alternatively, the facility could demonstrate 

that each of the facility’s intakes are designed with an intake velocity of less than 0.5 feet 
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per second. For details about the scope and applicability of today’s final rule, see 

sectionSection I above. 

Today’s final rule (as described in sectionSection IV above) establishes permit

application requirements for existing facilities in §§ 122.21 and 125.95, monitoring 

requirements in § 125.96, and record-keeping and reporting requirements in § 125.97. All 

existing facilities subject to the final rule that withdraw from one or more cooling water 

intake structures with a facility-wide DIF of greater than 2 mgd are required to comply 

with the national BTA impingement mortality standard at § 125.94(c) and national BTA 

entrainment standard at § 125.94(d). New units at existing facilities are required to meet 

the national BTA impingement mortality standard at § 125.94(c) and national BTAand

entrainment standardstandards at § 125.94(e). 

The final regulations also require the Director to review permit application 

materials submitted by each regulated facility, establish impingement mortality and 

entrainment requirements in accordance with this rule, and issue permits that include 

monitoring and record-keeping requirements (§ 125.98). The permit application 

requirements, monitoring, record-keeping, and reporting requirements for each of the 

compliance alternatives are detailed in the following sections. 

A. When Does the Final Rule Become Effective and How are the Requirements 

Sequenced in an Orderly Way? 

This rule becomes effective on [INSERT date 60 days after the date of 

publication in the Federal Register.]. The requirements in this rule will then be 

implemented in NPDES permits as the permits are issued. 
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EPA has sought to address the information and studies required in the permit 

application associated with ongoing permitting proceedings and subsequent permitting 

after the first implementation of this rule in a permit. The 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 to promulgation of today’s final rule. 

Therefore the rule includes several provisions that provide flexibility for the permit 

application requirements. First, in the case of any permit expiring after [INSERT date 45 

months after effective date of final rule], under § 125.95 the facility must submit 

permit application materials required in § 122.21(r) with its next NPDES permit renewal 

application. Second, in the case of any permit expiring prior to December 31, 

2016,[INSERT date 45 months after effective date of final rule], under § 125.95 a 

facility may request that the Director delaywaive the submission date of the permit 

application requirements of § 122.21(r) based on a showing by the owner or operator of 

the facility that it could not develop the information for which such a waiver is requested 

by the time required for submission of the permit renewal application. If the Director then 

chose to allow a delay for the submittal of any of the information requirements of § 

122.21(r), the Director would then determine the schedule for submission of any delayed 

requirements to be as soon as practicable. SecondThird, in the case of permit proceedings 

begun prior to the effective date of today’s rule, and issued prior to December 31, 

2016,[INSERT date 45 months after effective date of final rule], the Director 

mayshould proceed with any determination of BTA standards for impingement mortality 
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and entrainment without requiring all of the permit application requirements of § 

122.21(r).. See §§§ 125.9495(a)(2) and 125.98(g). In such circumstances where permit 

proceedings have already begun prior to the effective date of the rule, these facilities will 

still need to submitthesubmit the appropriate permit application materials found at § 

122.21(r) permit applications during their next application. Additionally, while EPA 

expects that many facilities will already comply with § 125.94(c), in some cases the 

facility will need to choose one of the compliance alternatives for IM in their subsequent 

permit cycle.92 ThirdIn particular, EPA expects the facility would submit the information 

required in § 122.21(r), and the Director would make a determination of BTA for 

entrainment for that facility. Only after the Director has established site-specific BTA 

requirements for entrainment reduction will the facility have to select the compliance 

alternative on which it will rely to meet the IM requirements of today’s rule. The Director 

may either amend the permit to include the IM requirements or include them in a 

subsequent permit if the Director determines the proposed controls are consistent with § 

125.94(c). The Director would establish a schedule incorporating each of these 

sequential actions. In addition, the rule allows the Director the flexibility to grant a 

request for a waiver of permit application requirements in § 122.21(r)(6) in order to 

accommodate the circumstances described here. See §§ 122.21(r)(1)(i) and 125.95(a). 

 

92 EPA’s costs do not assume zero compliance costs for prior BTA determinations or permit proceedings; 

all facilities were assessed costs on the basis of technologies in place as described in Section IX. 
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Fourth, in permit applications subsequent to the first permit issued under § 125.94(a)(1) 

with all requirements required information submitted under § 122.21(r), the Director may 

approve a request to reduce information required, if conditions at the facility and in the 

water bodywaterbody remain substantially unchanged since the previous application.93

See § 125.95(c). In addition to all of these flexibilities, EPA expects today’s final rule 

gives advance notice to affected facilities as to what the Agency’s expectations are 

regardingabout permit application materials and compliance schedules. 

While the final rule has both reduced and streamlined the permit application 

requirements, the EPA has determined that for many facilities, it may take as long as 39 

months to plan, collect, and compile the data and studies required to be submitted with 

the permit application (see Section C below for a more detailed discussion of each 

application element). The rule therefore specifies that [INSERT date 45 months after 

effective date of final rule] reflects the date after which all permit application 

requirements must be submitted as specified at § 125.95. Specific permit requirements 

may not need a full 39 months for completion, therefore the Director may establish a 

schedule for submission of the required permit application elements. For example, 

 

93 However, if conditions at the facility or in the water bodywaterbody have in fact changed substantially 

since the previous permit application, the Director will revisit data collection needs and possibly the BTA 

determination. The presence of any habitat designated as critical, or 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 potential for a substantial change that must be 

addressed by the owner/operator in subsequent permit applications, unless the facility received an 

exemption pursuant to 16 U.S.C. 1536(o) or a permit pursuant to 16 U.S.C. 1539(a) or there is no 

reasonable expectation of take.
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planning for required sampling may take 6 months, inclusive of establishing a sampling 

team, developing sampling protocols, and acquiring necessary equipment. Source water 

sampling and characterization under § 122.21(r)(4) includes two years’ worth of data. 

Therefore, the EPA expects a minimum of 30 months will be necessary for submission of 

§ 122.21(r)(4), assuming the facility collects new data; this timeframe could be shorter if 

the facility chooses to use existing biological data. Facilities choosing to comply with the 

IM requirements through either § 125.94(c)(5) or (c)(6) must collect at least 2 years data 

upon which the facility would demonstrate that the modified traveling screens or the 

facility’s systems of technology have been optimized to minimize impingement 

mortality. Therefore, the EPA expects a minimum of 30 months will be necessary for 

submission of § 122.21(r)(6), assuming the facility collects new data. Collection of 

entrainment characterization data and studies should occur in parallel with IM studies and 

sampling. Thus, after the initial 6 month planning period, facilities that do not already 

have recent entrainment characterization data will collect a minimum of 2 years 

entrainment data under § 122.21(r)(9). Facilities are expected to need an additional 9 

months to assemble the entrainment data and studies as required by § 122.21(r)(9) 

through (12). Therefore, the EPA has concluded that as many as 39 months will be 

necessary for final submission of all requirements under § 122.21(r). This time frame 

will be adequate for facilities under 125 mgd AIF; facilities over 125 mgd AIF also need 

to have their 122.21(r)(10) to (12) studies peer reviewed. The EPA expects 3 months will 

be needed for completion of peer review requirements and generation of a final report. 

However, many of the facilities over 125 mgd AIF were subject to the Phase II rule 
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before it was suspended (that is, all electric generators over 125 mgd AIF are also above 

50 mgd DIF), and likely need less time for up front planning and/or data collection. 

Therefore, the EPA has concluded that as many as 39 months will be adequate for these 

facilities to meet all requirements under § 122.21(r). These time frames are consistent 

with the timeline EPA included in the proposed rule, and also matches the 3 1⁄2 years 

previously provided in the Phase II rule for data collection and studies. EPA notes the 

submission of the studies required with the permit application should not be confused 

with the schedule for compliance with the BTA requirements, as discussed below. 

EPA has also sought to sequence the impingement mortality controls to be 

implemented after theso that a facility may select and implement these controls after the 

Director’s determination of controls on entrainment. With respect to entrainment 

requirements, existing facilities withdrawing greater than 125 mgd AIF must submit 

permit application materials including the studies prescribed in today’s final rule at § 

122.21(r)(9) through (13) in order to help the Director determine what entrainment 

controls to require at the facility. Facilities at or below this threshold must submit any 

information requested by the Director. The Director will then review these materials and 

determine if further entrainment controls are necessary. Once the BTA requirements for 

entrainment have been established, the facility would finalize its chosen method for 

compliance with impingement mortality under § 125.94(c). EPAIt would then expects 

thatbe appropriate for the Director wouldto develop a schedule on whichwhereby the 

facility would proceed to design, construct, and implement its technologies for 

impingement mortality, for entrainment, or for both together, where should the same 
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technology addresses both impacts. In this manner, the EPA has mergedharmonized the 

schedules for meeting both impingement mortality requirements and entrainment 

requirements. 

EPA further notes that approximately 2 percent of facilities have no controls in 

place for impingement or entrainment, or that a facility may choose to install modified 

traveling screens as part of its compliance response. In these circumstances, not only does 

EPA expect such decisions to be delayed until after the Director has determined the BTA 

requirements for entrainment, EPA acknowledges that the required optimization study of 

§ 122.21(r)(6) cannot be completed until after the technology has been designed and 

constructed. EPA has provided the Director the flexibility to establish an appropriate 

schedule for submission of such studies under § 125.95(a)(2). 

After the effective date of the regulation, when the first permit implementing the 

new regulatory requirements is issued, permitting authorities typically consider the need 

to allow facilities some period of time to come into compliance. Under today’s final rule, 

facilities will have to comply with the impingement mortality and entrainment 

requirements as soon as possiblepracticable according to the schedule of requirements set 

by the Director. The concept of “as soon as possible” is one that already exists for 

compliance schedules may be found in the generally applicable NPDES regulations at 40 

CFR 122.47. Because section 316(b) has no statutory deadline for meeting the “best 

available technology for minimizing adverse environmental impact” standard, there is no 

statutory bar to use of a compliance schedule in appropriate circumstances. The EPA 

recognizes that it will take facilities time to upgrade existing technologies, and install 
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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 

serviceservices to orderly, functioning markets. EPA expects It is appropriate for the 

Director willto take this into account when establishing a deadline for compliance. The 

EPA expects anyAny such schedule would take into account factors provided in § 

125.98(c), such as measures needed to maintain adequate energy reliability by an electric 

generating facility, or extenuating circumstances such as scheduled production outages at 

a manufacturing facility. 

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 

will also meetscomply with the requirements for impingement mortality viastandard 

under § 125.94(c)(1). As such, the Director would schedule compliance with the 

impingement mortality requirements to match the schedule for entrainment requirements. 

Further, EPA recognizes that in some cases, especially where additional entrainment 

control technologies are required, the facility could require a lengthy period of time to 

design, construct, and implement control technologies. Therefore, the rule authorizes the 

Director, at § 125.94(gh), to establish interim BTA requirements in a facility’s schedule 

of requirements, for impingement mortality, entrainment, or both, where necessary on a 

site-specific basis. 
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In contrast to the proposed rule, today’s final rule does not include a requirement 

for compliance with the impingement mortality performance standards within eight years. 

EPA expects, however, that the final rule will generally result in compliance along the 

same timeframe.within a similar period of time. The combination of permit 

reissuanceissuance, the Director’s determination of BTA for entrainment, and the 

subsequent schedule of requirements for impingement mortality will result in some 

facilities, particularly those already in a permitting proceeding, or with controls similar to 

what the new permit requires, being in compliance within a very short time frame. Some 

facilities whothat are not now in a permitting proceeding may need as much as three and 

a half 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. In some cases, the Director’s determination for entrainment may result 

in a facility meeting both the impingement mortality and entrainment BTA requirements 

in fewer than eight years. All facilities will be required to follow their schedule as 

determined by the Director. 

EPA notes that there is a three-year period after the effective date of this rule 

before Directors will be receiving permit applications containing the full set of 

application requirements in § 122.21(r). EPA is aware that currently many NPDES 

permits for facilities with a CWIS have been administratively continued. For these 

administratively continued permits, the Director should consider if any permits would 

need additional updated information to support the permit issuance decision. The Director 
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may, under 40 CFR 122.21(g)(13), request additional information including any permit 

application requirements in § 122.21(r). 

B. How doesDoes the Final Rule Reduce Biological Monitoring Requirements? 

The EPA has streamlined the biological data and study requirements for both 

impingement mortality and entrainment into one comprehensive set of permit application 

requirements and provisions. The source water baseline biological characterization, 

entrainment biological characterizationSource Water Baseline Biological 

Characterization Data, impingement technology performance optimization study, 

Entrainment Characterization Study, and where applicable, biologicalentrainment

performance studies are all conducted within the same two year time frame prior to 

submission of an application for a permit. Further, as shown in Exhibit VIII-1, EPA 

anticipatesEPA's analysis indicates that more than 99 percent of existing facilities will 

choose an alternative for impingement mortality that does not require continual biological 

compliance monitoring. Thus any required biological monitoring data consists solely of 

that required to be collected to meet the permit application requirements. See Section F 

for further discussion. 

Exhibit VIII-1. EPA’s projections of how facilities will choose to comply with the IM Requirements 

IM Compliance Alternative Intake Counta Percent of Total Intakes 

Closed-cycle recirculating systemsystemc 307 18% 

Design velocity 362 21% 

Actual velocity 226 13% 

Existing offshore velocity capcapc 10 1% 

Modified traveling screens 488 29% 

System of technologies 278 17% 

Impingement Mortality Performance Standard 12 0.7% 

De minimis **b

 **b
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Total 1682 100% 

a. EPA’s compliance costs for each facility are based on the sum of the facility’s intake level compliance costs. Some 

facilities have more than one intake. See IX.B.2 for more information on the use of the survey data. 

b. EPA doeshas not knowestimated which facilities will be determined to be “de minimusminimis” under § 125.94(c)(1211) by 

the Director. For purposes of this analysis, EPA has assumed no facilities fall under the “de minimis” provision. 

c. EPA is not projecting facilities will install closed-cycle recirculating systems or offshore velocity caps to comply with the IM 

requirements, rather these facilities already have these technologies installed. 

By merging the data collection and studies into the permit application 

requirements, EPA expects approximately half of all affected facilities will be able to 

complete the initial permit application within a few months.94 In the case of a facility that 

was not previously required to collect data and conduct studies, it may take three 

years’up to 45 months lead time for a permit to be applied for, and additional time for the 

permit to be issued. Although the permit application times may be longer for the first 

permit cycle after this rule, this is a tradeoff for the flexible IM requirements. 

Once the permit is issued, EPA anticipates very few, if any, facilities will be 

required to conduct ongoing biological compliance monitoring related to impingement 

controls; for more details, see Section F and Exhibit VIII-4. Instead, for each subsequent 

permit cycle each facility would either (1) demonstrate to the Director that facility 

operations and water bodywaterbody characteristics are substantially unchanged, or (2) 

update any biological characterization data. Anticipating that NPDES permits are 

renewed when they expire, the update to the facility’s biological characterization and any 

 

94 For example, facilities that were subject to Phase II will have already collected most of the data and 

information as part of the Phase II rule issued February 16, 2004 and implemented up until suspension of 

that rule on July 9, 2007. 
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corresponding biological performance evaluations would be conducted approximately 

every five years. 

C. What Information Will I Be Required to Submit to the Director When I 

Apply for My NPDES Permit? 

Today’s final rule establishes, at § 122.21(r), permit application requirements for 

all facilities subject to the requirements of § 125.94. Each permit application element at § 

122.21(r) will beis described in more detail below. The final rule requires existing 

facilities to prepare and submit muchsome of the same information as previously required 

for new facilities subject to subparts I or N (i.e.., Phase I new power plants and 

manufacturers or Phase III new offshore oil and gas facilities), namely the information at 

§ 122.21(r)(2) through (4). In addition, the rule adds subparagraphs for existing facilities 

to the regulations at § 122.21(r)(4), as well as (r)(65) through (13) to include the 

information and study requirements specific to existing facilities. 

In the case of a new unit constructed at an existing facility, EPA expects much of 

the information submitted by the facility in previous permit applications would still be 

current and relevant. Therefore, EPA has reduced the permit application requirements to 

those necessary to update the facility’s previously submitted information under § 

122.21(r)(2), (r)(3), (r)(4), (r)(5), (r)(6), (r)(7) and (r)(8). In other words, the new unit 

permit application is intended to describe the changes to these documents as a result of 

the addition of the new unit. In addition, the facility must submit information specific to 

the new unit’s chosen compliance method at § 122.21(r)(14). 
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All existing facilities are required to complete and submit permit application 

studies to describe the source water bodywaterbody (§ 122.21(r)(2)), cooling water intake 

structures (§ 122.21(r)(3)), characterize the biological community in the vicinity of the 

cooling water intake structure (§ 122.21(r)(4)), cooling water system (§ 122.21(r)(5)), 

and operational status (§ 122.21(r)(8)). In addition, a facility that previously conducted 

an entrainment performance study (§ 122.21(r)(7)) must also submit that information, 

although § 122.21(r)(7) does not impose a requirement to collect new 

informationFacilities that already use a closed-cycle recirculating system must still 

submit this information in their permit application. The Director will need, for instance, 

the biological sampling data in (r)(4) to serve as a record basis for their BTA 

determination in the permit. Furthermore, in Phase I, new facilities were required to be 

commensurate with closed-cycle, to meet the 0.5 fps velocity limit, and to collect two 

years’ worth of biological data to establish a record basis for impacts at the facility. In 

addition, the data collected here is important to inform an owner/operator’s evaluation of 

whether and if so what threatened or endangered species or designated critical habitat are 

or may be present in the action area. 

All existing facilities must describe their existing impingement and entrainment 

technologies or operational measures and a summary of their performance, including but 

not limited to reductions in impingement mortality and entrainment due to intake location 

and reductions in total water withdrawals and usage (§ 122.21(r)(5)(iii)). All facilities 

must also complete and submit their chosen compliance method for impingement 

mortality (§ 122.21(r)(6)). This includes identification of any requests for BTA 
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determinations under § 125.94(c)(11) de minimis rates of impingement or § 125.94(c)(12) 

low capacity utilization power generation units. In addition, the owner or operator of an 

existing facility must submit the information required under paragraph (r)(6) for the 

alternative specified at 40 CFR 125.94(c) that the owner or operator of an existing facility 

chooses to rely on as its method of compliance with the BTA Standards for Impingement 

Mortality specified in 40 CFR 125.94. Because the IM compliance options § 125.94(c)(1) 

through), (2), and (4) include pre-approved technologies, the owner or operator of a 

facility choosing one of these fourthree options to comply with the IM requirements does 

not have either biological studies or biological compliance monitoring related to the 

applicable IM standard. Compliance options § 125.94(c)(3), (5)), and (6) are streamlined 

options. For these twothree options, the permit application element § 122.21(r)(6) further 

requires a site-specific study for the purposes of technology optimization to minimize 

impingement mortality, including additional biological monitoringdata collection that in 

most cases would occur during the same two year period of source water baseline 

biological data collection for the Source Water Baseline Biological Characterization Data

required under § 122.21(r)(4) to characterize the baseline, and a demonstration that the 

operation of specific technologies at your facility have been optimized to minimize 

impingement mortality. The owner or operator of a facility choosing one of these 

twothree options to comply with the IM requirements do not have ongoing biological 

compliance monitoring as part of the applicable IM standard. As discussed in the 
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previous section, the Director can establish a schedule95 for submitting the optimization 

study if the facility first needs to install additional technology for IM. 

All existing facilities, particularly electric generating facilities above 50 MGD,

may submit to the Director additional permit application studies to describe biological 

survival studies that address technology efficacy and other studies on entrainment at the 

facility (§ 122.21(r)(7)). This requirement does not impose any new or additional study 

requirements. This permit application element includes the submission of existing studies 

conducted by or relevant to the facility. Further, the burden of this requirement has been 

reduced since proposal by only referring to studies of entrainment studies. 

All existing facilities that withdraw more than 125 mgd AIF96 of water for cooling 

purposes must also submit additional information to characterize entrainment and assess 

the costs and benefits of installing various potential technological and operational 

controls. These facilities are required to submit to the Director additional permit 

application studies including the § 122.21(r)(9), entrainment characterization 

studyEntrainment Characterization Study; § 122.21(r)(10), comprehensive technical 

 

95 The Director could, for example, issue a permit before the optimization study has been completed, and 

include a schedule for submission of the optimization study in the newly issued permit. 

96 AIF is calculated from the most recent three years’ data or five years in subsequent permit cycles. As 

such, AIF is a variable number. It is possible that a facility could transition from below 125 mgd to above 

125 mgd if the facility significantly increases withdrawal of cooling water, such as if the facility increases 

capacity or if it adds a new unit. In these cases, the facility will then be required to conduct the studies and 

meet the permit application requirements at (r)(9)-(13). This consequence is intended to incentivize 

facilities to reduce or reuse water for cooling, thereby avoiding the need for additional permit application 

studies.
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feasibilityComprehensive Technical Feasibility and cost evaluation studyCost Evaluation 

Study; § 122.21(r)(11), benefits valuation study (unless waived by the director);Benefits 

Valuation Study; and § 122.21(r)(12), nonNon-water quality environmentalQuality 

Environmental and other impacts assessment. A facility that is required to submit one of 

these studies must also submit (r)(13), peer review.Other Impacts Assessment. As with 

the biological monitoringdata collection required of some facilities under § 122.21(r)(6), 

EPA expects biological monitoringdata collection for the purposes of entrainment 

characterization to occur during the same two year period of biological data collection 

required under § 122.21(r)(4) or (9). EPA notes that facilities below the 125 mgd 

threshold are not automatically exempt from entrainment requirements. The Director may 

determine that entrainment studies may be required or that entrainment controls may need 

to be installed for any cooling water intake structure. See the Section VI of this preamble 

for more information. 

The final rule further requires the studies at (r)(10) through (r)(12) be subject to 

an external peer review as required at (r)(13), with (r)(9) being); a separate peer review is 

not required for § 122.21(r)(9), as it is implicitly reviewed via its use in (r)(10) and 

(r)(11). EPA expects the facility would first notify the Director of the peer review in 

advance. For example, facilities could identify their peer reviewers near the beginning of 

their biological monitoringdata collection for the required entrainment characterization 

studiesEntrainment Characterization Study at § 122.21(r)(129). Since a facility’s permit 

application requires two years of biological data, EPA expects this is more than enough 

time for the facility to identify peer reviewers, and for the Director to disapprove of a 
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peer reviewer or require additional reviewers. Further, this provides the Director ample 

opportunity to confer with those agencies with responsibility for fish and wildlife 

potentially affected by the cooling water intake structure, including other Federal, State, 

and Tribal agencies. Similarly, in the case of permits for electric generating utilities, EPA 

expects this is enough time to confer with state co-regulators such as public utility 

commissions, or independent system operators whose responsibility it is to ensure 

reliability of the electricity grid. To minimize the overall time required to conduct a peer 

review, all studies conducted by the facility under § 122.21(r)(10) through (12) will be 

subject to peer review at the same time, in a holistic fashion. Additional guidance on 

conducting peer review is available on EPA’s Peer Review Program website at 

www.epa.gov/peerreview. EPA expects the Director will use the permit application 

information, studies, and peer review results to assess the impingement and entrainment 

impacts of the cooling water intake structure and determine appropriate technological or 

operational controls, or both, as necessary. 

While all facilities must submit § 122.21(r)(2) through (6) and (r)(8) and (r)(7),

where applicable, (r)(7), EPA has reduced the permit application requirements based on 

the facility’s chosen compliance method for impingement mortality. Exhibits VIII-2 and 

VIII-3 below illustrate the permit application requirements as they relate to an existing 

facility’s chosen compliance methods. EPA expects permit application requirements for 

new units will consist of updates to previously submitted permit applications for the rest 

of the existing facility at which the new unit is being constructed. 
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For a new unit at an existing facility, EPA expects that only the appropriate and 

relevant updates to the existing facility’s permit application materials are required. (in 

addition to newly developed materials required at § 122.21(r)(14)). For example, the 

facility would update § 122.21(r)(3) to indicate the addition of the new unit, any new 

intakes associated with the new unit, expected operational characteristics, etc. For the 

owner or operator of a new unit choosing to comply via § 125.94(e)(1) to employ a 

closed-cycle recirculating system, the application materials under § 122.21(r)(9)-(12) are 

not required. For the owner or operator of a new unit opting to comply via § 125.94(e)(2), 

the application materials required under §For the owner or operator of a new unit and 

with an AIF greater than 125 mgd, the permit application materials under § 122.21(r)(9)-

(13) are required. In those circumstances where data specific to the facility indicate that 

compliance with the requirements of paragraphs (e)(1) or (2) of § 125.94 for a 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, or significant adverse impacts on local energy markets, the 

rule requires the submission of such data as part of 122.21(r)(14). EPA notes that when a 

new unit increases an existing facility’s AIF greater than 125 mgd, the permit application 

requirements also include 122.21(r)(9) through (13). Further, facilities may need several 

years to complete studies and data collection and, depending on the types of controls 

selected, may need additional time to design and construct their technology. Thus while 

the rule requires the permit application for a new unit at least 180 days prior to 
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commencing cooling water withdrawals, it is in the facility’s best interest to submit this 

data well in advance in order to prevent any delays in the Director’s review of permit 

application materials and subsequent issuance or renewal of the facility’s NPDES permit. 

For the owner or operator of a new unit opting to comply via 125.94(e)(2) the application 

materials required under 122.21(r)(14) must demonstrate entrainment reductions 

equivalent to 90 percent or greater of the reduction that could be achieved through 

compliance with § 125.94(e)(1). Further, if the addition of the new unit’s cooling water 

withdrawals are sufficient to raise the facility’s cumulative AIF above 125 mgd, then the 

facility as a whole would be required to submit the materials required under § 

122.21(r)(9)-(13125.94(e)(1). 

Exhibit VIII-2. Summary of permit application requirements for existing facilities according to existing 

facilities’ chosen method for compliance with impingement mortality standard 

Compliance 

approach to 

Impingement 

§ 122.21 subsection 

(r)(2) (r)(3) (r)(4) (r)(5) (r)(6) (r)(6)(i) (r)(6)(ii) (r)(8) 

Closed-cycle 

recirculating 

system 

Yes Yes Yes Yes Yes No No Yes 

Design intake 

velocity 

Yes Yes Yes Yes Yes No No Yes 

Actual intake 

velocity 

Yes Yes Yes Yes Yes No No Yes 

Existing offshore 

velocity cap 

Yes Yes Yes Yes Yes No No Yes 

Modified traveling 

screens 

Yes Yes Yes Yes Yes Yes No Yes 

Combination of 

technologies 

Yes Yes Yes Yes Yes No Yes Yes 

Impingement 

Mortality 

Yes Yes Yes Yes Yes Maybe Maybe Yes 
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Performance 

Standard 

Exhibit VIII-3. Summary of permit application requirements for existing facilities: entrainment 

Compliance approach to 

Entrainment 

§ 122.21 subsection 

(r)(7) (r)(8) (r)(9) (r)(10) (r)(11) (r)(12) (r)(13) 

Closed-cycle recirculating 

system 

NoYes Yes NoVar.a NoVar.a NoVar.a NoVar.a NoVar.a

Director BTA entrainment 

determination: facility AIF 

above 125 mgd 

Yes Yes Yes Yes Yes Yes Yes 

Director BTA entrainment 

determination: facility AIF 125 

mgd or below 

Maybe Maybe Maybe Maybe Maybe Maybe Maybe 

a. Director has the discretion to waive.

In addition, the Director may set information requirements not included in today’s 

rule to aid in best professional judgment permitting, such as will occur for entrainment at 

facilities below 125 mgd AIF not, and for impingement and entrainment at existing 

facilities below 2 mgd DIF, neither of which are required by today’s rule to submit items 

(r)(9) through (r)(13), or existing facilities below 2 mgd.). The Director may find aspects 

of the permit application requirements described below to be relevant in such situations. 

A summary of each permit application requirement follows.97 

1. § 122.21(r)(2) Source Water Physical Data 

This requirement is unchanged from the Phase I rule and the 2004 Phase II rule. 

The facility is required to submit data to characterize the facility and evaluate the type of 

 

97 Where a closed-cycle recirculating system withdraws greater than 125 mgd AIF, the information required 

in § 122.21(r)(9) to (13) is required, unless the Director reduces or waives some or all of the information 

required. 
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water bodywaterbody potentially affected by the cooling water intake structure. The 

applicant is required to submit a narrative description and scaled drawings showing the 

physical configuration of all source water bodies used by the facility, including areal 

dimensions, depths, salinity and temperature regimes, and other documentation that 

supports the determination of the water bodywaterbody type where each cooling water 

intake structure is located; identification and characterization of the source water 

body’swaterbody’s hydrological and geomorphological features, and the methods used to 

conduct any physical studies to determine the intake’s area of influence in the water 

bodywaterbody and the results of such studies; and locational maps. The Director uses 

this information to evaluate the appropriateness of any design or technologies proposed 

by the applicant. 

2. § 122.21(r)(3) Cooling Water Intake Structure Data 

This requirement is unchanged from the Phase I rule and the 2004 Phase II rule. 

This data is used to characterize the cooling water intake structure and evaluate the 

potential for impingement and entrainment of aquatic organisms. Information on the 

design of the intake structure and its location in the water column allows evaluation of 

which species and life stages might be subject to impingement and entrainment. A 

diagram of the facility’s water balance is used to identify the proportion of intake water 

used for cooling, make-up, and process water, as well as any cooling water supplied by 

alternate sources, such as reuse of another facility’s effluent. The water balance diagram 

also provides a picture of the total flow in and out of the facility, and is used to evaluate 

gray water, waste water, and other reuses in the facility. The applicant is required to 
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submit a narrative description of the configuration of each of cooling water intake 

structure and where it is in the water bodywaterbody and in the water column; latitude 

and longitude in degrees, minutes, and seconds for each cooling water intake structure; a 

narrative description of the operation of each of cooling water intake structure, including 

design intake flows, daily hours of operation, number of days of the year in operation and 

seasonal changes, if applicable; a flow distribution and water balance diagram that 

includes all sources of water to the facility, recirculating flows, and discharges; and 

engineering drawings of the cooling water intake structure. 

3. § 122.21(r)(4) Source Water Baseline Biological Characterization Data 

This information is similar to that required in the Phase I rule. Existing facilities 

are required to characterize the biological community in the vicinity of the cooling water 

intake structure and to characterize the operation of the cooling water intake structures. 

This supporting information must include existing data if they are available. However, 

the facility may supplement the data using newly conducted field studies if it chooses to 

do so. The information the applicant must submit includes identification of data that are 

not available and efforts made to identify sources of the data; a list of species (or relevant 

taxa) for all life stages and their relative abundance in the vicinity of the cooling water 

intake structure; and identification of the species and life stages that would be most 

susceptible to impingement and entrainment. All species should be evaluated, including 

the forage base, threatened and endangered species whose range of habitat includes the 

waters where the facility’s intakes are located, and those species most important in terms 

of significance to commercial and recreational fisheries. In addition, the applicant must 
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identify and evaluate the primary period of reproduction, larval recruitment, and period of 

peak abundance for relevant taxa; data representative of the seasonal and daily activities 

(e.g., feeding and water column migration) of biological organisms in the vicinity of the 

cooling water intake structure; identification of all threatened, endangered, and other 

protected species whose range of habitat includes the waters where the facility’s intakes 

are located; and. In addition, instead of the information required at § 122.21 (r)(4)(vi), the 

owner or operator of an existing facility or new unit at an existing facility must identify 

all Federally-listed threatened and endangered species and/or designated critical habitat 

that are or may be present in the action area pursuant to paragraph § 125.95 (f). The 

action area can generally be considered the area in the vicinity of impingement and 

entrainment at the cooling water intake structure. The applicant must also include

documentation of any public participation or coordination with Federal or State agencies 

undertaken. If the applicant supplements the information with data collected using field 

studies, supporting documentation for the Source Water Baseline Biological 

Characterization Data must include a description of all methods and quality assurance 

procedures for sampling, and data analysis including a description of the study area; 

taxonomic identification to the lowest taxon possible of sampled and evaluated biological 

assemblages (including all life stages of fish and shellfish); and sampling and data 

analysis methods. The sampling or data analysis (or both) methods used must be 

appropriate for a quantitative survey and based on consideration of methods used in other 

biological studies performed in the same source water bodywaterbody. The study area 

should include, at a minimum, the area of influence of the cooling water intake structure. 
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The applicant may also identify protective measures and stabilization activities that have 

been implemented and describe how these measures and activities affected the baseline 

water condition in the vicinity of the intake. 

EPA is adding items (ix) and (x) to the source water baseline biological 

characterization data for existing facilities. EPA is adopting item (ix) essentially as it was 

proposed, which provides for descriptions of other activities that may affect the baseline 

biological characterization. Previous measures to protect threatened or endangered 

species should be noted as part of (ix). This item was not required in Phase I for new 

facilities because the new facility has not yet done anything that would affect baseline 

biological characterization. EPA is requiring item (xitem (ix), (x) and (xi) to the Source 

Water Baseline Biological Characterization Data for existing facilities. Item (ix) simply 

defines the term “Source Water Baseline Biological Characterization Data.” EPA is 

requiring item (xi), identification of fragile species found at the facility. EPA notes that in 

contrast to the proposed rule, the permit application does not require submission of the 

proposed “species of concern.” EPA found that the term “species of concern” was too 

similar to terms as used in the context of T&E (threatened and endangered) species, and 

may cause confusion over existing Services or State requirements for such species. 

Further, despite EPA’s efforts to distinguish between species of concern and RIS 

(representative indicator species) in the NODA (77 FR 34325, June 11, 2011), EPA 

found that many commenters were still confused by the language. Instead, EPA is 

adopting the term “fragile species” and using the term exactly as it is used with the 

impingement mortality data and criteria used in calculating the impingement mortality 
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standards of the rule. The definition for “fragile species” at § 125.92 is 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 identified 

fragile species in the Chapter 11 of the TDD for the proposedfinal rule. Further, EPA is 

providing examples, in the list of those 14 specific species in today’s regulatory 

definition as a non-exclusive list. This list includes only those species specifically 

analyzed as part of the performance standards development. If a permit applicant can 

sufficiently demonstrate a record basis, the permitting Director may deem a particular 

species to be a fragile species for the purpose of a particular permit. 

American shad (Clupeidae), bay anchovy (Engraulidae), and blueback herring 

(Clupeidae) belong to families that wereare specifically identified in the proposed rule 

TDD Chapter 11 as examples of species that may be, at the Director’s discretion, 

excluded from performance limitsstandards on the basis of impingement survival. As 

another example, threadfin shad (a species not specifically identified as fragile in today’s 

rule) are prone to fall dieoffdie-off when the water temperatures reachtemperature 

reaches 42 degrees. The EPA does not intend for such naturally occurring mortality to be 

counted against a facility’s performance in reducing impingement mortality. EPA is 

aware of limited success in flow reduction and behavioral deterrent systems in protecting 

fragile species. However, there are no demonstrated and available technologies for 

industry as a whole to address fragile species. EPA has long recognized these species as 

having low survival rates under the best of conditions, and established different 

mechanisms to address these in today’s final rule. Today’s BTA for impingement 
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mortality allows the Director to establish site-specific controls under § 125.94(c)(119) to 

address fragile species. 

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. Further, use of “fragile 

species” instead of “species of concern” greatly increases the transparency of the 

Agency’s impingement mortality performance standards. 

In addition, EPA notes that (r)(4)(vi) requires the applicant to submit information 

on all threatened and endangered species, not just those T&E species that are fish or 

shellfish. Examples of T&E species that are not fish or shellfish are corals, sea turtles 

and marine mammals. 

4. § 122.21(r)(5) Cooling Water System Data 

The Director uses this data in determining the appropriate standards that would be 

applied to the facility. Facilities are able to use this information, along with the water 

balance diagram required by § 122.21(r)(3), to demonstrate the extent to which flow 

reductions have already been achieved. at the facility level. The applicant must provide 

the following information for each cooling water intake structure they use: a narrative 

description of the operation of the cooling water system and its relationship to cooling 

water intake structures (including the use of helper towers); the proportion of the design 

intake flow that is used in the system including a distribution of water used for contact 

cooling, non-contact cooling, and process uses; a distribution of water reuse (to include 
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cooling water reused as process water, process water reused for cooling, and the use of 

gray water for cooling) [NOTE to reviewers: EPA would like to cite here as support for 

this material the draft DOE report on “U.S. Energy Sector Vulnerabilities to Climate 

Change and Extreme Weather” when it is public.];); description of reductions in total 

water withdrawals including cooling water intake flow reductions already achieved 

through minimized process water withdrawals; description of any cooling water that is 

used in a manufacturing process either before or after it is used for cooling, including 

other recycled process water flows; the proportion of the source water bodywaterbody

withdrawn (monthly); the number of days of the year the cooling water system is in 

operation and seasonal changes in the operation of the system, if applicable. The 

applicant must also submit a description of existing impingement and entrainment 

technologies or operational measures and a summary of their performance, including for 

example reductions in entrainment due to intake location and reductions in total water 

withdrawals and usage, and efficiencies in energy production for each producing unit that 

result in the use of less cooling water, including for example combined cycle and 

cogeneration. For example, the applicant may provide comparative density data for the 

intake to demonstrate the extent to which location of the intake has reduced adverse 

environmental impact. The additional information at § 122.21(r)(5)(iii) is specific to 

those process units that use cooling water for purposes other than power generation or 

steam, and where the owner or operator intends to comply with the BTA for IM through 

either the use of flow reduction measures or the reuse of other water for cooling purposes. 
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5. § 122.21(r)(6) Chosen Method of Compliance with Impingement Mortality 

Standard 

Today’s final rule is flexible in providing seven different compliance options for 

meeting impingement mortality requirements. Under § 122.21(r)(6), the facility must 

identify its approach to meet the impingement mortality performance standards. The 

facility must identify the compliance method for the entire facility or, alternatively, the 

compliance method for each cooling water intake structure at the facility. Finding it to be 

unnecessary because the facility will already have a set of requirements to meet based on 

its chosen method of compliance, EPA has eliminated the proposed requirement for a 

separate Impingement Mortalityimpingement mortality reduction plan. In addition, 

monitoring and studies conducted under the reduction plan is no longer required by all 

facilities. Instead today’s final rule specifies monitoringdata collection requirements only 

in those instances where the facility must demonstrate a particular performance outcome 

as described below. 

Facilities choosing to comply with § 125.94(c) by operating a modified traveling 

screen (under § 125.94(c)(5)) must submit an impingement technology performance 

optimization study under § 122.21(r)(6)(i). The site-specific study must demonstrate the 

modified traveling screen as defined at § 125.92 has been optimized to minimize 

impingement mortality. The study must include a minimum of two years of biological 

monitoringdata collection. This time frame is consistent with the requirements at 

paragraph (r)(4)(iv) to identify primary periods of reproduction and peak abundance, as 

well as (r)(4)(v) to provide data representative of the seasonal activities, both of which 
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would require at least one year worth of monitoring.data collection. EPA expects 

facilities will either use existing biological data already required under (r)(4) to complete 

their site-specific impingement studies, modify their biological data collections under 

(r)(4) to be comprehensive and inclusive, use existing performance studies, or collect 

supplemental data necessary to make their demonstrations. If a facility is using 

previously collected data or studies that are more than 10 years old, the facility must 

demonstrate the data is still relevant and representative of the facility. If a facility intends 

to return organisms to a different waterbody from which they are withdrawn, a request 

for consideration of this must be made to the Director under (r)(6).

The rule specifies sampling at least monthly during the two year monitoringdata 

collection effort of the impingement technology performance optimization study, and 

requires documentation of methods used including counting of moribund organisms, 

latent mortality, holding times, and counting of entrapment. The Director may establish 

more frequent monitoring as well as specify monitoring methods and additional protocols 

to be used.collection, as well as specify sampling methods and additional protocols to be 

used. If the facility intends to return fish and shellfish to a different waterbody than the 

source waterbody that is used to withdraw cooling water, EPA expects this would be 

identified as part of § 122.21(r)(6)(i). While EPA does not expect this situation occurs 

very frequently, the permit application information at (r)(6)(i) along with (r)(4) would 

provide the Director the information needed to determine whether such a return location 
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is appropriate.98 If the site-specific impingement study demonstrates the modified 

traveling screen (as defined at § 125.92) has been optimized to minimize impingement 

mortality, the Director may then determine the modified traveling screen is the best 

technology available for impingement mortality at the site. The Director would then 

include permit conditions that ensure the technology will perform as demonstrated. If the 

Director determines that additional data is required to identify permit operating 

conditions, the Director has the authority to establish such requirements under § 

125.95(d). Note that the EPA envisions the study will function to optimize performance, 

which is not the same as requiring a study merely demonstrating a specific numeric 

limitslevel of performance for impingement mortality havehas been or can be achieved. 

For the majority of facilities, EPA expects annual performance using modified traveling 

screens will exceed the Agency’s calculated average annual performance standards for 

impingement mortality. Several examples of modified traveling screens in EPA’s record 

show annual performance for impingement mortality that is superior to the numeric 

limitimpingement mortality performance standard (e.g., lower than 10 percent). 

Similarly, facilities choosing to comply with § 125.94(c) by operating a system of 

technologies (under § 125.94(c)(6)) that will achieve the impingement mortality standard 

must submit a impingement technology performance optimization study under § 

 

98 For example, the St. Lucie generating facility determined that this arrangement was not appropriate at 

their site; see DCN 10-6515. The Brunswick facility, has a fish return flume that goes to a tributary rather 

than the intake canal or the river. This arrangement places the aquatic organisms away from the intake 

canal and in a more gentle water environment to increase the organisms’ survival; see DCN 10-6569. 
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122.21(r)(6)(ii). The site-specific study must provide a description of the technologies, 

operational measures, or monitoringsampling approaches or any combination of them to 

be used to meet the BTA for impingement mortality. The study must demonstrate that the 

system of technologies has been optimized to minimize impingement mortality. EPA 

notes the “system” may consist of one or more technologies already in place, or may be 

combined with newly installed technologies. Further, the study must include a minimum 

of two years of biological monitoringdata collection, as just described. 

The EPA is aware that it is possible for a facility to reduce its rate of 

impingement, but for the same number of impinged fish die. This has the unintended 

consequence of increasing the percent impingement mortality calculated by the facility. 

EPA does not intend for such facilities to be penalized for significant reductions in 

impingement rates obtained through existing technologies and practices in place. 

Therefore, one difference in the required study for the system of technologies compliance 

alternative (as compared to the study required for modified traveling screens) is an 

understanding that operational measures, best management practices, intake location, and 

other technologies do not always lend themselves to direct impingement mortality 

measurements or monitoring.data collection. Thus the study can include flow 

measurements and monitoring the rate of impingement (as opposed to directly monitoring 

mortality) as described below. 

If the facility chooses to rely on credit for reductions in the rate of impingement 

already achieved, the impingement technology performance optimization study must 

document the reductions to be used as credit. The estimated reductions in impingement 
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must be based on a comparison of the facility to a once-through cooling system with a 

traveling screen located on the shoreline of the source water bodywaterbody. For 

example, a facility with an offshore intake, an intake canal, or an intake located 

immediately downstream of a dam in a cold water stream, could demonstrate the 

population of fish at the intake is lower in these areas, resulting in lower rates of 

impingement. This provision is intended to allow a facility that conducted or completed a 

baseline characterization under the Phase II rule to use that same information as part of 

their demonstration under this rule. 

As discussed in Section VI, EPA has identified flow reduction as one of the best 

ways to reduce both impingement and entrainment. Today’s final rule, as part of the 

system of technologies compliance option at § 125.94(c)(6), provides the owner or 

operator of a facility the opportunity to demonstrate flow reduction as part of meeting the 

IM performance standards. If the facility chooses flow reduction to reduce impingement, 

the study at § 122.21(r)(6)(ii) must include two years of intake flows measured daily. 

This flow information plus the data collected under § 122.21(r)(4)(iv) would be used to 

document how the flow reduction results in a reduced rate of impingement, as well as 

documenting the extent to which such reductions are seasonal or intermittent. Many 

pumps operate at only one speed, which doesn’t allow the facility to adjust its intake flow 

to changing conditions. As a potential application of § 125.94(c)(6), EPA is aware of a 

manufacturing facility that installed multiple pumps of different sizes, and the plant 

operator only utilized those pumps that were necessary to obtain the exact amount of 

cooling water needed. As another example, variable speed drives offer many facilities an 
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opportunity to reduce their intake flows by as much as 10 percent. Variable speed drives 

are available at all facilities, and EPA expects variable speed drives will be considered 

when replacing existing recirculating pumps,; however, EPA also acknowledges variable 

speed drives may not be practical in all cases. Nevertheless, EPA expects variable speed 

drives will be considered by the Director when establishing entrainment requirements 

under today’s final rule. EPA provided an example of how a facility would receive credit 

for existing technologies in the NODA (see 77 FR 34322, June 11, 2011). An additional 

sample calculation that includes flow reduction is provided later in this section. 

The study must identify each of these contributing components, and requires the 

calculation of the impingement mortality reflecting each component of the system. The 

impingement technology performance optimization study must demonstrate the system of 

technologies has been optimized to minimize impingement mortality. In addition, the 

study must document the percent impingement mortality reflecting optimized operation 

of the total system of technologies, operational measures, and best management practices 

at § 122.21(r)(6)(ii)(D). The Director may then determine the system of technologies is 

the best technology available for impingement reduction at the site. The Director would 

then include permit conditions that ensure the technology will perform as demonstrated. 

6. § 122.21(r)(7) Entrainment Performance Studies 

EPA proposed that a facility must submit all previously conducted performance 

studies, but has revised this provision in the final rule to include only entrainment related 

studies. Impingement performance studies, where relevant, are already part of the permit 

application at § 122.21(r)(6). This avoids imposing a requirement on all facilities to 
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submit previous impingement studies that may be unnecessary, and eliminates a burden 

on the Director to review all such studies, many of which may no longer be relevant.99

Under today’s final rule, the applicant must submit a description of any biological 

survival studies conducted at the facility and a summary of any conclusions or results, 

including the following: site-specific studies addressing technology efficacy, throughplantfacility entrainment survival (distinguished for eggs and larvae), and entrainment 

studies;analyses, or studies conducted at other locations including a justification as to 

why the data are relevant and representative of conditions at the facility. Because of 

changes in the water bodywaterbody over time, studies older than 10 years must include 

an explanation of why the data are still relevant and representative of conditions at the 

facility. If the data are no longer relevant and representative, the Director may reject the 

data. The Director uses such studies when establishing technology-based requirements 

for entrainment. Permit applicants are not required to conduct new studies simply to 

fulfill this requirement. This requirement is rather aimed at obtaining results for relevant 

studies that have already been conducted as part of past permit proceedings or for other 

purposes even if those studies were not completed or conducted entirely as planned. 

 

99 For example, the study may be old and no longer representative, the study may address a pilot study of a 

technology no longer under consideration by the facility, or the facility may have already selected one of 

the compliance methods for IM based on pre-approved technologies at § 125.94(c)(1) through), (2) or (4). 
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7. § 122.21(r)(8) Operational Status 

The applicant must submit a description of the operational status of each unit for 

which a cooling water intake structure provides water for cooling, including the 

following: descriptions of each individual unit’s operating status including age of the 

unit, capacity utilization for the previous five years (including any unusual or extended 

outages that significantly affect the facility’s reporting of flow, impingement, or other 

data), and any major upgrades completed in the past 15 years (e.g., boiler or condenser 

replacement, changes to fuel type, a new production line); a description of completed, 

approved, or scheduled uprates and NRC (Nuclear Regulatory Commission) relicensing 

status for nuclear facilities; a description of plans or schedules for decommissioning or 

replacement of units; and a description of current and future production schedules for 

manufacturing facilities. The Director will use such information in determining the BTA 

for entrainment as well as when establishing compliance schedules. For example, where 

the remaining useful plant life is considerably shorter than the useful life of an 

entrainment technology or where a facility has a planned retirement within the next 

permit cycle, this information is useful to support a determination regarding that specific 

entrainment technology. This information would also be used under § 125.94(c)(1312) to 

document infrequently used power generating units that are used only in emergency 

circumstancesoperate with a capacity utilization of less than 8 percent averaged over a 

24-month block contiguous period and that the Director may therefore determine 

warrants IM controls less stringent than (c)(1) tothrough (c)(7). With respect to 

entrainment, the BTA for entrainment is determined by the Director for each site, and 
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energy reliability is one factor the Director may consider when establishing entrainment 

controls (see § 125.98(f)(3)). EPA expects the information submitted on energy reliability 

will be considered by the Director when making a BTA determination for entrainment for 

low CUR units.

8. § 122.21(r)(9) Entrainment Characterization Study 

Facilities that withdraw greater than 125 mgd AIF must develop a study that 

includes a minimum of two years of entrainment monitoring.data collection. EPA 

envisions the facility would modifyextend the data collection methods and frequency to 

develop the source water characterization already required by § 122.21(r)(4) to develop 

the Entrainment Characterization Study. The study would include complete 

documentation of the monitoringdata collection period and frequency of entrainment 

characterization, and an identification of the organisms monitoredsampled to the lowest 

taxon possible. The monitoringdata collection must be representative of the entrainment 

at theeach intake, and the study must document how the location of the intake in the 

water bodywaterbody and the water column are accounted for. The study must document 

the intake flows associated with the monitoring.data collection. Consistent with the 

permit application requirements requiring biological monitoringdata collection at § 

122.21(r)(4) and (6), EPA requires at least two years of data to sufficiently characterize 

annual, seasonal, and diel variations in entrainment, including variations related to 

climate, weather, spawning, feeding, and water column migration. Also consistent with 

the permit application requirements at § 122.21(r)(4) and (6), facilities may use historical 

data that are representative of current operation of the facility and conditions at the site 
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with documentation regarding the continued relevance of the data. The study must 

include analysis of the monitoring data to determine total entrainment and entrainment 

mortality. Documentation in the study must include the method in which latent mortality 

would be identified, and all methods and quality assurance/quality control procedures for 

sampling and data analysis would be described. The sampling and data analysis methods 

must be appropriate for a quantitative survey. 

This information is to be used towill help the Director determine the site-specific 

BTA for entrainment. For facilities with no entrainment technologies currently in place, 

this information characterizes the total potential for entrainment. The information can 

also be used to demonstrate that technologies and other measures already in place, or sitespecific factors such as intake location or design, already reduce entrainment. For 

example, abundance data might demonstrate lower comparative densities that can 

significantly lower entrainment rates. The information could also be used by new units

under § 125.94(e)(2) to demonstrate that an alternative technology or combination of 

technologies reduce entrainment at that site to a level commensurate with closed-cycle 

cooling. 

9. § 122.21(r)(10) Comprehensive Technical Feasibility and Cost Evaluation Study 

The owner or operator of the facility must submit an engineering study of the 

technical feasibility and incremental costs of candidate entrainment control technologies. 

The study must include an evaluation of technical feasibility of closed-cycle cooling and 

fine-mesh screens with a mesh size of 2mm2 mm or smaller, reuse of water or alternate 

sources of cooling water, and any other entrainment reduction technologies identified by 
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the applicant or requested by the Director. This study must include a description of all 

technologies and operational measures considered (which could include alternative 

designs of closed-cycle recirculating systems such as natural draft cooling towers, hybrid 

designs, compact or multi-cell arrangements, or the conversion of helper towers to a fully 

recirculating system); and documentation of factors that make a candidate technology 

impractical or infeasible for further evaluation. 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. 

For the analysis of water reuse and use of alternate sources of cooling water, the 

owner or operator must examine the available alternatives for reuse of effluent from 

within the facility or from other dischargers in the vicinity. [NOTE to reviewers: EPA 

would like to cite here as support for this material the draft DOE report on “U.S. Energy 

Sector Vulnerabilities to Climate Change and Extreme Weather” when it is public.] The 

volume of water available need not be for the full intake flow; reuse of water could 

contribute to a partial reduction in flow at the facility. Additionally, if the facility were to 

retrofit to a closed-cycle system, the significant reduction in flow may make nearby 

alternative sources more feasible. This analysis should include an estimate of the cost to 
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build any new infrastructure (e.g., piping, pump houses) and the ongoing operational 

costs (e.g., pump costs) for the Director’s consideration. 

The final rule requires that the cost information be presented as both the facility’s 

compliance costs and the social costs, and in net present value (NPV) terms and the 

corresponding annual value. Social costs are the costs estimated from the viewpoint of 

society, rather than individual stakeholders. Social cost represents the total burden 

imposed on the economy; it is the sum of all opportunity costs incurred. See Chapter 8 of 

EPA’s 2010 Guidelines for Preparing Economic Analyses. (DCN 10-3258). Some 

adjustments to facility compliance costs to produce social costs cause them to be higher 

than compliance costs, while other cause social costs to be lower. Although a facility 

makes investment decisions by taking tax consequences into account (after-tax costs), the 

favorable tax treatment of investments is viewed as a transfer and not a real resource cost, 

thus pre-tax costs are used in social cost analysis. From society’s viewpoint, costs in the 

future must be amortized and discounted to net present value using a social discount rate, 

rather than a market cost of capital as reflected in market interest rates. The Office of 

Management and Budget (OMB) Circular A-4 (DCN 10-3266) instructs agencies to use 

both 3 percent and 7 percent discount rates. Certain administrative costs are not borne by 

a facility, but rather the permit director, and should be included in social costs. by the 

Director, and are social costs. Compliance costs include the facility’s administrative 

costs, including costs of permit application, while the social cost adjustment includes the 

Director’s administrative costs. EPA has estimated the Directors’ administrative costs in 

the ICR for the final rule, and describes the methodology for estimating these costs in 
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detail in the EA. Facilities may adopt a similar approach to including Director’s 

administrative costs in their social cost estimates. In addition, this component is not 

expected to be large or to vary significantly across technology options considered. 

From a facility’s viewpoint, downtime costs include lost net revenue, while from 

society’s viewpoint, if another facility is dispatched or inventory of manufactured goods 

can be sold, the only social cost of downtime is any increase in marginal costs of 

production at other facilities dispatched or the cost of holding inventory. Unless a facility 

can demonstrate that its costs of compliance will result in lower overall supply in the 

markets in which its products are sold, and that the effect of the lowered supply is an 

increase in market price and lower quantity of product sold, the facility should not make a 

social cost adjustment to reflect these larger market impacts. 

In addition to the required social costs, the owner or operator may choose to 

provide facility level compliance costs; however, such costs must be provided and 

discussed separately from social costs. The cost evaluation component of this study must 

include engineering cost estimates of all technologies considered above and also discuss 

and provide documentation of any outages, downtime, energy penalties or other effects 

on revenue. The cost evaluation should be based on least-cost approaches to 

implementing each candidate technology while meeting all regulatory and operational 

requirements of the plantfacility. Depreciation schedules, interest rates, further 

consideration of remaining useful life of the facility as discussed in § 122.21(r)(8), and 

any related assumptions must be identified. The owner or operator of the facility must 
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obtain peer review of the Comprehensive Technical Feasibility and Cost Evaluation 

Study, as described in sectionSection 12. 

10. § 122.21(r)(11) Benefits Valuation Study 

The owner or operator of the facility must submit a detailed discussion of the 

magnitude of water quality benefits, both monetized and nonmonetized, of the candidate 

entrainment reduction technologies evaluated in § 122.21(r)(10) and using data in the 

entrainment characterization studyEntrainment Characterization Study in § 122.21(r)(9), 

including). Each category of benefits should be described narratively, and when possible 

benefits should be quantified in physical or biological units and monetized using 

appropriate economic valuation methods. This includes incremental changes in the 

impingement mortality and entrainment of individual fish and shellfish, and monetization 

for all exposed life stages, estimation of these changes to the extent appropriate in stock 

and feasible using the best available scientific, engineering,harvest levels of commercial

and economic informationrecreational species, and description of any monetization. This 

may include monetization using market values, market proxies (e.g., models based on 

travel costs or other methodologies), benefits transfer and stated preference methods. 

Benefits that cannot be monetized should be quantified where feasible and discussed 

qualitatively where not. The study must identify increasesincreased or decreased thermal 

discharges, and must evaluate the potential changes in facility capacity, operations, and 

reliability due to relaxed permitting constraints related to thermal discharges. The study 

must also include discussion of recent mitigation efforts already completed and how these 

have affected fish abundance and ecosystem viability in the intake structure’s area of 
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influence. Finally, the study must identify other benefits to the environment and the 

community, including improvements for mammals, birds, and other organisms and 

aquatic habitats. The owner or operator of the facility must obtain peer review of the 

benefits evaluation study, as described in sectionSection 12. EPA expects peer reviewers 

to have appropriate qualifications (e.g., fisheries biologist, economist) for the subject 

matter. The Director may consult with EPA and Federal, State and Tribal fish and 

wildlife management agencies with responsibility for fish and wildlife potentially 

affected by the cooling water intake structure(s) to determine which peer review 

comments must be addressed by the final study. The director may waive the requirement 

to conduct the benefits valuation study if the director does not intend to use this 

information in determining the entrainment reduction requirements for the facilityThe 

dollar values in the social benefits analysis should be based on the principle of 

willingness-to-pay (WTP), which captures monetary benefits by measuring what 

individuals are willing to forgo in order to enjoy a particular benefit. While the Director 

must consider benefit and cost information, the Director will also determine if this 

information is of sufficient rigor to make a decision on entrainment controls on the basis 

of this information. For instance, the Director may decide not to rely on benefit-cost 

information in establishing the entrainment controls when the benefits analysis includes 

only a qualitative discussion of nonuse benefits. Willingness-to-pay for nonuse benefits 

can be measured using benefits transfer or a stated preference survey. However, the rule 

does not require the Director to require a facility owner or operator to conduct or submit a 

stated preference survey to assess benefits. 
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11. § 122.21(r)(12) Non-Water Quality Environmental and Other Impacts Assessment 

The owner or operator of the facility must submit a detailed discussion of the 

changes in non-water quality environmental and other factors attributed to technologies 

or operational measures, or both, considered. These changes may include, for example, 

increases or decreases in the following: energy consumption; air pollutant emissions and 

their health and environmental impacts; noise; safety concerns, such as the potential for 

plumes, icing, and availability of emergency cooling water; grid reliability, including an 

estimate of changes to facility capacity, operations, and reliability due to cooling water 

availability; consumptive water use (including effects of surface water evaporation of 

thermal discharges); and facility reliability, such as production of steam and impacts to 

production based on process unit heating or cooling. The owner or operator of the facility 

must provide for peer review of the Non-Water Quality Environmental and Other Impacts 

Assessment as described in the following section. 

12. § 122.21(r)(13) Peer Review 

The owner or operator of the facility must provide for peer review of the permit 

application studies required at § 122.21(r)(10) Comprehensive Technical Feasibility and 

Cost Evaluation Study, § 122.21(r)(11) Benefits Valuation Study, and § 122.21(r)(12) 

Non-Water Quality and Other Impacts Assessment. While facilities that withdraw more 

than 125 mgd AIF must conduct these studies and therefore must provide for peer review, 

facilities that withdraw equal to or less than 125 mgd AIF may have study requirements 

including peer review as determined by the Director. In today’s final rule, EPA did not 

adopt separate peer review requirements for the Entrainment Characterization Study at § 
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122.21(r)(9), because this data would be included in the other components that are peer 

reviewed. Further, the entrainment characterization study is used in the Comprehensive 

Technical Feasibility and Cost Evaluation Study, Benefits Valuation Study, and NonWater Quality and Other Impacts Assessment, and these studies are already subject to 

peer review. For these reasons, EPA reduced the burden in the final rule by eliminating 

the peer review requirement for entrainment characterization. 

EPA recognized at proposal that in many cases it is more efficient for permit 

applicants to combine the required studies into one document and have them reviewed 

holistically by a single set of peer reviewers. Such an approach is allowed by the final 

rule, as long as the peer review panel has the background appropriate to conduct a 

complete and combined review and the Director approves. 

The Director may consult with Federal, State and Tribal fish and wildlife 

management agencies with responsibility for fish and wildlife potentially affected by the 

cooling water intake structure(s). Further, the Director may require the owner or operator 

of the facility to include additional peer reviewers of the studies. EPA expects peer 

reviewers to have appropriate qualifications (e.g., in the fields of biology, engineering) 

for the subject matter. An explanation for any significant reviewer comments not 

accepted must be included in the final study submission. Additional guidance on 

conducting peer review is available on EPA’s Peer Review Program website at 

www.epa.gov/peerreview. 
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13. § 122.21(r)(14) New Units 

New units at existing facilities must identify the compliance method for the new 

unit under the permit application requirements at § 122.21(r)(14). Where the facility 

complies with BTA standards for entrainment at § 125.94(e)(1) by reducedreducing its

intake flows commensurate with that of a closed-cycle recirculating system, (as defined 

at § 125.92(c)(1)), the BTA standards for impingement mortality will have been met by § 

125.94(c)(1). To comply with the alternative at § 125.94(e)(2), there must be a 

demonstration that entrainment reductions equivalent to 90 percent or greater of the 

reductions that could be achieved through compliance with § 125.94(e)(1).100 In this case, 

permit application requirement § 122.21(r)(14) requires this demonstration to include the 

entrainment characterization studyEntrainment Characterization Study at § 122.21(r)(9). 

The Director may determine additional data and information, including monitoringdata 

collection, is necessary to make the demonstration. 

 

100 Note that a new unit may construct a new intake structure or utilize capacity from an existing intake 

structure. For the former, the requirements of (e)(1) and (e)(2) are1are simple to conceptualize and apply. 

But for the latter, EPA clarifies that the new unit requirements only apply to that portion of the flow that is 

serving the new unit. For a new unit using an existing intake structure that chooses to comply using (e)(1), 

demonstrating that the new unit achieves the required reduction in flow should be a relatively simple 

exercise in identifying intake flows and the distribution of cooling water from the intake structure. For a 

new unit using an existing intake structure that chooses to comply using (e)(2), the facility would 

demonstrate that it has reduced entrainment for that portion of the intake flow serving the new unit by 90%; 

percent; the facility would not be required to reduce entrainment for the flow of the entire intake structure 

by 90%, percent, unless the Director makes such a site-specific determination for entrainment at the 

existing units as well. 
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D. When Are Permit Application Studies Due? 

The owner or operator of a facility applying for reissuance of a permit must 

submit the information required at § 122.21(r) to the Director no later than 180 days 

before the current permit expires. Those facilities that were subject to the section 316(b) 

Phase II rule from February 16, 2004 until suspension of that rule on July 9, 2007 were 

already collecting some information required at § 122.21(r). EPA has structured this rule 

to take advantage of those data and expects facilities to use them when they satisfy 

requirements for permit applications. 

In some cases, required permit application information might have been collected, 

but reports might not have been generated or finalized prior to the rule suspension in 

2007. Further, facilities not subject to the Phase II rule might not have collected this 

information, (e.g., existing power plants below 50 mgd DIF and all existing 

manufacturers,) might not have collected this information or might not have collected 

information to identify permit operating conditions. In those cases, facilities would have 

to collect additional data in order to have two years of biological monitoringdata 

collection. EPA expects associated studies and reports will take several additional months 

to complete. For this reason, EPA has established a provision for permit application 

submittal for a permit expiring prior to December 31, 2016,[INSERT date 45 months 

after the effective date of the final rule], allowing the Director flexibility to delay 

application requirements based on a showing by the owner or operator that it could not 

develop the information by the time required for submission of the permit application. 

The Director would then establish a schedule for submission of the delayed permit 
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application requirements. EPA notes that the Director has the discretion to require 

additional studies, monitoringdata collection, or an on-site inspection as part of the permit 

process. 

Facilities whose permit expires after [INSERT date 45 months after effective 

date of the final rule] would submit all required materials in § 122.21(r) with their 

permit renewal application. 

New units at existing facilities must submit the information required at § 

122.21(r) to the Director no later than 180 days before commencing operation of the new 

unit. Because these units are being constructed at a facility that is already operating, the 

facility will have already submitted many of the permit application materials. The 

addition of a new unit would require an update of or supplement to permit application 

materials that have already been submitted. New units take significant time and resources 

to plan, design, and construct,; therefore the final rule does not have a provision to waive 

permit application requirements based on a showing by the owner or operator that it 

could not develop the information by the time required for submission of the permit 

application. For permit renewals subsequent to the first permit issued under today’s rule, 

the new unit would be included in the assessment of the entire facility and would no 

longer require unique permit application submissions. As discussed previously, the owner 

or operator is encouraged to submit applications well in advance of the 180 day 

requirement to avoid delay.

EPA is aware that some intake structures withdraw from a manmade lake or 

reservoir that is stocked and managed by a State or Federal natural resources agency. In 
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some cases, the biological characterization of the source water is heavily influenced by 

the actions of the natural resources agency. Further, the results of biological 

monitoringdata collection and studies may be confounded by such actions. Today’s final 

rule at § 125.95(a)(3) gives the Director discretion to waive some or all of the permit 

application requirements of § 122.21(r) in such circumstances. 

In permit terms subsequent to the firtfirst permit issued under the final rule, the 

facility will re-submit the § 122.21(r) permit application studies, andwhile the rule still 

includes two years of biological monitoringdata collection for some facilities. In this 

manner, the biological characterization over time would be routinely evaluated, i.e., every 

5 years under a standard permit cycle. To reduce the burden of such monitoring and data 

collection, however, the final rule provides that the owner or operator of a facility may 

submit a request to the Director to reduce the information required. See 40 CFR 

125.95(c). In most cases, EPA anticipates the facility would make any such request prior 

to conducting its two years of biological monitoringdata collection. Therefore the request 

for reduced information requirements must be submitted to the Director at least two years 

and six months before the expiration of the facility’s NPDES permit. The Director may 

approve such a request if conditions at the facility and in the water bodywaterbody

remain substantially unchanged since the previous permit application.101 EPA expects the 

 

101 The presence of any habitat designated as critical, or 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 potential for a substantial change that must be addressed by the 
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Director would assess the relevant previously submitted information and determine 

ifwhether it remains representative of current source water, intake structure, cooling 

water system, and operating conditions. Accordingly, the Director may accept or reject 

any part of the request. 

E. How Will the Director Determine the Best Technology Available for 

Minimizing Adverse Environmental Impacts? 

1. Review and Approval of Permit Application Materials 

Under today’s rule, the Director will review all materials submitted by an existing 

facility with its permit application to determine appropriate NPDES permit conditions 

and requirements reflectingto minimize impingement mortality and entrainment. As 

stated at 40 CFR 125.98(a), the Director shall not issue a permit before receiving a permit 

application form and any supplemental information which are completed to his or her 

satisfaction (see existing Permit Application and Special NPDES Program Requirements 

at 40 CFR 122.21(e)). 

Facilities with a design intake flow at or below 2 mgd will continue to have 

permit conditions set on a case-by-case, best professional judgment basis under 40 CFR

125.90(b) and 401.14. For such facilities, however, the Director may choose to apply 

some portions of the permit application conditions in today’s rule, to aid in the BPJ 

determination. 

 

owner/operator in subsequent permit applications, unless the facility received an exemption pursuant to 16 

U.S.C. 1536(o) or a permit pursuant to 16 U.S.C. 1539(a) or there is no reasonable expectation of take. 
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The Director is encouraged to expeditiously provide any comments on submitted 

materials so the facility can make responsive modifications to its information gathering 

activities. For permit applications subsequent to the first permit issued under today’s rule, 

the Director could indicate whether reduced or different information must be submitted 

with the permit application. More specific responsibilities are described below: 

(1) a. If the Director has made a BTA determination for entrainment before the 

effective date of the rule, and substantially the same information was already submitted 

and considered by the Director in making that determination, under § 125.98(bg) the 

Director may proceed with the Determination of BTA without requiring the owner to 

submit the information required in § 122.21(r). 

To clarify further, EPA has included a “transition” provision at § 125.98(g) of 

today’s rule that makes it clear that for any facility that has submitted a permit 

application before the effective date of the regulation, the Director may select the best 

approach to development and implementation of the next permit. These provisions are 

intended to avoid any unnecessary delay in recently submitted permit applications or 

draft permits. EPA expects that facilities will continue with any monitoringdata collection

requirements, study requirements, and schedules in recently issued permits. 

(2) b. If the Director establishes a compliance schedule under § 125.94, the 

Director will establish a schedule that sets requirements as soon as possible.practicable. 

In establishing the schedule, the Director is encouraged to consider the extent to which 

those technologies proposed to be implemented to meet the requirements of § 125.94(d) 

or (e) will be used, or could otherwise affect a facility’s choice of technology, to meet the 
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requirements of § 125.94(c). Impacts of thermal discharges, along with other stressors, 

might be a relevant consideration when assessing benefits of technologies to reduce 

impacts of cooling water intakes or discharges. The Director is also encouraged to 

consider energy reliability, transmission capacity, and grid requirements when 

establishing a schedule for electric power generating facilities. The Director may confer 

with local and regional electric power agencies and state utility regulators when 

establishing a schedule for electric power generating facilities (see DCN 12-XXX10-

6860 for information on the approach taken by California). The Director may determine 

that extenuating circumstances (e.g., lengthy scheduled outages, future production 

schedules) warrant establishing a different compliance date for any manufacturing 

facility. 

(3) c. The Director will review the permit application materials and studies 

submitted under § 122.21(r) and determine which entrainment controls are 

necessaryappropriate. Factors whichthat must be considered and factors whichthat may 

be considered in making the determination are provided at § 125.98. The Director 

willmust issue a written explanation for the BTA determination and must make this 

determination, and any other information submitted by third parties, available with the 

permit for public review. This determination is expected to be issued as part of the 

permit’s statement of basis under 40 CFR 124.7. 

2. Role of Social Cost-Benefit Analysis in Permit Determinations 

In deciding what technology to require a permittee to install to address 

entrainment, the Director may undertake an evaluation of social costs and benefits of 
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implementing such requirements. This analysis will be based on the information 

submitted by the applicant, supplemented by any information submitted by third parties, 

and additional information as determined appropriate by the Director. EPA recognizes the 

resource limitations faced by permitting authorities and does not generally expect that the 

Director would develop additional information on which to base the evaluation of social 

benefits and costs, although the Director may opt to do so. EPA is committed to working 

with the states to support their site-specific permitting decisions with the benefit of the 

SAB review once it is completed. This analysis should evaluate benefits and costs from 

the perspective of society as a whole, rather than costs and benefits accruing to limited 

parties (e.g., very local populations or the permittee, which presents a limited set of 

information to the Director). 

It is also important to note that the stated preference survey conducted by EPA 

which was discussed in the June 12, 2012 Notice of Data Availability (77 FR 34927) 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 site-level permitting decisions. 

Today’s final rule does not require the Director to require a facility owner or operator to 

conduct or submit a stated preference survey to assess benefits. Further, the rule does not 

limit the Director’s discretion to consider non-water quality impacts in determining 

whether further entrainment measures are justified. 
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A number of cost elements should be accounted for in assessing the social cost of 

entrainment technology implementation. These are summarized below.

a. Technology installation cost. 

These peer-reviewed engineering cost estimates of the physical construction of 

candidate entrainment technologies at the facility are required. These costs would be 

provided by the applicant under § 122.21(r)(10). 

b. Installation downtime cost. 

Installation of closed-cycle cooling systems will often require generating facilities 

to take additional downtime beyond ordinary annual maintenance downtime. An estimate 

of downtime cost to the facility is required under § 122.21(r)(10). EPA expects a facility 

will document that portion of downtime that is incremental to any downtime the facility 

already incurs due to, for example, routine maintenance outages, overhauls, refueling, 

and periodic replacement of equipment that is at the end of its useful life. Downtime costs 

to the facility include the value of lost production (e.g., electricity) minus any variable 

cost savings, as well as any other costs to the facility associated with downtime 

(shutdown and startup routines, special maintenance protocols, and such)etc.) minus any 

savings associated with downtime. DowntimeIf they are considered in the social costs 

analysis, downtime costs must be adjusted to reflect production made up by other 

facilities or firms if they are considered in the social costs analysis, , because these 

temper the real resource costs from society’s viewpoint. The cost of downtime is 

determined on a different basis for social cost. Specifically, the cost of downtime to 

society is the cost incurred for other facilities and generating units to make up the 
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electricity or manufactured goods that would have otherwise been generated by the 

facility minus the cost that would have otherwise been incurred by the facility incurring 

downtime. This difference in cost reflects the additional cost, if any, that society must 

pay to generate the replacement goods, and may differ substantially from the cost of 

downtime to the facility. 

c. Energy penalty cost. 

Operation of closed-cycle cooling systems may impose an energy penalty. Here, 

EPA is using energy penalty to mean only mean the opportunity costs associated with 

reduced power production due to derating (turbine backpressure). Energy penalty does 

not include the costs to operate pumps and fans associated with closed-cycle cooling, 

which are operation and maintenance costs (and covered below). Under well-established 

principles in benefit-cost analysis, the energy penalty is not an opportunity cost to 

society, except to the extent that suppliers making up the lost production have higher 

variable costs of production, and only that cost differential is a social cost. Again, an 

assessment of these costs to the facilitycost of the energy penalty to the facility is not the 

opportunity cost to society. Instead, the cost to society is the cost of generating the 

electricity, whether incurred by the regulated facility or another facility, that is no longer 

available for consumption because of the energy penalty. This cost may be incurred by 

the facility, if it can increase the energy input to, and output from, the generating unit to 

generate the electricity that is otherwise no longer available for consumption, or by 

another generating unit if the regulated unit cannot make up the electricity. In either case, 

the social cost of the energy penalty is the cost of generating the electricity that would 
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otherwise be available for consumption except for the energy penalty. Again, an 

assessment of these costs would be determined under the § 122.21(r)(10) demonstration. 

d. Operation and maintenance costs for the entrainment technology equipment. 

The cost of energy to operate the entrainment technology for electric generators 

should appear in the operation and maintenance costs, and not in the energy penalty. 

These costs, which would be estimated as part of the § 122.21(r)(10) assessment, would 

enter the social cost framework unchanged, because it is a real opportunity cost.along 

with other labor and materials costs. In the same way as described above, the social cost 

of the energy required to operate entrainment technology is the cost for generating this 

electricity, as it is otherwise no longer available for end-use consumption. This cost could 

be incurred by the regulated facility, if it has sufficient capacity to make up the loss, or by 

another facility, if the regulated facility is not capable of generating the electricity that is 

no longer available for end-use consumption. 

e. Other administrative expenses – e.g.,. 

This includes additional permitting or reporting expenses, or both. Being aFor

social cost conceptcosts, the estimate should include the costs to the facility and those 

expected to be incurred by the Director. 

 EPA has estimated the Directors’ administrative costs in the ICR for the final 

rule, as explained in the EA, and facilities may adopt a similar approach to estimating 

these costs at the permit level. For assessing social cost, the cost elements outlined above 

would typically be accounted for on a real cost basis—that is, pre-tax and without 

adjusting for future inflation. Costs are tallied over an appropriate time frame, which will 
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typically be the expected useful life of the technology installation or the remaining life of 

the facility, if less. Costs should be calculated as both net present value and annualized 

values, using an appropriate social discount rate. The applicant should document the basis 

for the discount rate chosen, and its methodology and calculations. 

f. Benefits 

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 installation of a closed-cycle cooling system, fine 

mesh screens, or other entrainment technologies. All benefits, including monetized, 

quantified and qualitative benefits, should be considered in this assessment. The benefits 

assessment would typically look at a range of potential benefit mechanismscategories, 

including increased harvest for commercial fisheries, increased use values for 

recreational fisheries, and non-usenonuse values (existence and bequest values). 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 non-usenonuse

values. Otherwise, non-usenonuse values should be evaluated quantitatively and/or 

qualitatively. Quantitative analysis, even without monetization, can be quite useful in 

evaluating non-usenonuse benefits. For example, quantifying impacts to forage and 

threatened and endangered species, and other indirect impacts on the aquatic 

environment, might allow the Director to derive a much more complete understanding of 
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benefits as compared to a qualitative narrative, even if not directly comparable to 

monetary costs. 

Quantifying and valuing the benefit categories listed above involves significant 

challenges, as described in the BA. For example, assessing the productivity and value of 

commercial fisheries involves estimating the expected increases in commercial yield of 

economically valued species over time as a result of reduced impingement mortality and 

entrainment, and valuing these at market prices minus any incremental production costs 

associated with the incremental catch. Similarly, assessing recreational use benefits 

involves estimating the improvements in recreational fishing opportunities resulting from 

reduced impingement mortality and entrainment, and assigning a value to these 

improvements. The value assignment is based on the estimated population profile—in 

particular, number and proximity to affected water resources—of recreational users, the 

availability of alternative competing water resources for recreational usage, and the 

resulting estimated change in demand for use and value of the affected water resources 

based on reduced impingement mortality and entrainment and increased recreational 

fishing performance. EPA acknowledges this could be difficult to do even on a sitespecific basis. 

Non-useNonuse benefits, which encompass existence and bequest values, include 

impacts in such areas as population resilience and support, nutrient cycling, natural 

species assemblages, and ecosystem health and integrity. Non-useNonuse values include 

improving the survival probability of a threatened or endangered species if present in the 

vicinity of the facility. Benefits might also need to be assessed beyond the vicinity of the 
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facility’s intake if migratory species are affected by the intake. Residual impacts of 

thermal discharges might also be appropriate to consider in the social benefits 

calculation. 

In much the same way as described for the social cost assessment, social benefits 

are tallied yearly over the expected performance life of the compliance technology. If 

possible, thisThis tallying should account for the “phase-in” of benefits (e.g., benefits 

may build up over time as the impingement mortality and entrainment reductions affect 

commercial fisheries productivity). Benefits are computed on a present value basis and 

annualized using an appropriate discount rate as described above. The same discount rate 

should be used for benefits and costs. Often, it is appropriate to calculate benefits and 

costs using more than one discount rate. For example, for regulatory impact analysis, the 

Office of Management and BudgetOMB recommends that federalFederal agencies use 

both a 3 percent and a 7 percent rate. However, comparisons between specific benefit and 

cost numbers should always involve values computed using the same rate. 

The resulting estimates of social cost and benefits maymust be taken into 

accountconsidered in reaching determinations on whether to require a permittee to install 

entrainment technology and the specific level of entrainment technology to be installed. 

The Director may reject otherwise available technologies as the BTA requirements for 

entrainment controls if the social costs of compliance are not justified by the social 

benefits, or if there are other adverse impacts that cannot be mitigated that the Director 

deems to be unacceptable. If all technologies considered have social costs not justified by 

the social benefits, or have unacceptable adverse impacts that cannot be mitigated, the 
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Director may determine that no additional control requirements are necessary beyond 

what the facility is already doing. The Director should document the basis for such a 

determination and include it in the public notice for the draft permit.

 (4) 3. Streamlined Process 

The process for complying with the impingement mortality standards is expected 

to be highly streamlined. As shown in Exhibit VIII-1, EPA expects more than 99 percent 

of facilities will comply by one of the six compliance options that do not require 

continual biological compliance monitoring (one of the fourthree compliance alternatives 

based on pre-approved technologies or one of the twothree streamlined compliance 

alternatives). If a facility chooses to comply by operating a modified traveling screen, the 

Director will review the impingement technology performance optimization study, 

including the identification of species, duration and structure of the study, and any 

monitoring requirements. 

(5) 4. De Minimus Provision 

The Director may, based on a review of data submitted under § 122.21(r), 

conclude that the documented rate of impingement at the cooling water intake structures 

is so low that no additional controls are warranted. As described in section I.A.H, low 

flow facilities may in particular be candidates for such consideration, although the 

authority of the Director is not limited to low flow facilities. The Director may want to 

consider facility withdrawal rates in relation to the mean annual flow of the river and 

possible co-location with other CWISs when making a de minimis determination. Notice 

of this determination would be included in the draft permit made available for public 
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comment, and the Director’s response to any comment on this determination must be 

included in the record for the final permit. EPA expects this determination to occur only 

in those circumstances where the rate of impingement may be so exceptionally low as to 

be insignificant. EPA considers low rates of impingement to be measured as an organism 

or age-one equivalent count, and not as the effect of impingement on fish populations. 

The Director may require monitoringdata collection to demonstrate support for a de 

minimis level of impingement. The Director should seriously consider finding § 

125.94(c)(12) to be not applicable whenever a facility’s intake is located in waters in the 

range or designated critical habitat of threatened or endangered species. The Director 

should also seriously consider finding § 125.94(c)(12) to be not applicable whenever a 

facility’s intake is located in waters not meeting a designated aquatic life use, whether the 

waters are currently subject to a TMDL or not. In addition, EPA does not expect that a 

de minimis exemption would apply to facilities with no technology present other than 

trash racks. EPA has determined , a technology that nearly all facilities employ. In 

making a determination that no additional controls are warranted, the Director may wish 

to consider factors such as whether the waters are subject to a TMDL, nonattainment of 

for an aquatic life use, the waters are not attaining a designated use or habitat for , and 

there would be more than minor detrimental effects on threatened or endangered species 

will confound a Director’s ability to make a de minimis determination.or critical habitat. 

The Director will still establish proper operation and maintenance conditions in the 

permit whenever making a de minimis finding that no additional controls are warranted. 

EPA did not identify sufficient data to establish a numeric threshold for making such a 
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determination, but intendsEPA notes that the de minimis provision for impingement does 

not necessarily mean a facility has a de minimis level of entrainment. The life stages 

affected by impingement are different than those affected by entrainment, and low counts 

of impingeable life stages do not always mean the counts of entrained organism are 

similarly low. Since the entrainment requirements are already determined by the Director

for such circumstances to be very limited. Further, theeach site, EPA concluded that 

specific regulatory language for de minimis entrainment was unnecessary. 

5. Low Capacity Utilization Units 

The Director may consider less stringent controls for intakes dedicated to low 

capacity utilization rate (CUR) power generating units operated solely for emergency 

purposes. If an existing facility has a cooling water intake structure used exclusively for 

one or more existing electric generating units, each with an annual average capacity 

utilization rating of less than 8 percent for each of the previous 5 yearsaveraged over a 

24-month block contiguous period, the owner or operator may request that the Director 

establish BTA standards for impingement mortality for that cooling water intake structure 

which are less stringent than (c)(1) to (c)(7). This provision at 125.94(c)(13) applies to 

cooling water intakes for those generating units that supply power only occasionally, 

such as a generating unit maintained to provide backup power resources in a crisis, 

natural catastrophe, or when regular systems fail. This provision does not apply those 

electric generating units run when there is a high demand or peak demand for electricity, 

such as seasonally operated peaking units. The owner or operator would demonstrate 

whether they have an intake serving one or more low capacity utilitization power 
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generating units used solely for emergency purposes in permit applicationWhen 

determining the permit’s IM requirements at 122.21(r)(3associated with the low CUR 

unit, the Director may consider, after conferring with any appropriate state co-regulators 

(such as public utility commissioners) and (8).with regional transmission organizations, 

independent system operators or other planning authorities, the significance of the unit’s 

operation to the overall reliability of electric power in the area. 

(6) In addition, in determining the IM requirements associated with a low CUR 

unit, the Director should consider any seasonal factors for affected species that might 

justify seasonal limits on the unit’s operation, for example any increased impacts 

resulting from the unit’s operation during spawning runs. Also, when considering the 

presence and potential effects to threatened and endangered species, the Director should 

consider whether the life stages present at the location are at risk of being impinged or 

entrained at the low CUR unit’s cooling water intake. 

In the event that the Director determines less stringent controls for intakes 

dedicated to low capacity utilization power generating units are appropriate, they should 

consider, at a minimum, the following in establishing controls: 

Strategies for minimizing water withdrawal during stand by periods of operation, 

startup/shutdown, and on-line periods of operation; 

The effectiveness of installing variable speed pump drives to reduce water 

withdrawals during all periods of operation, particularly during stand-by periods of 

operation; and 
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The effectiveness of installing alternative equipment (e.g. behavioral deterrents) 

to minimize impingement mortality. 

The owner or operator would demonstrate whether they have an intake only 

serving one or more low capacity utilization power generating units in permit application 

requirements at § 122.21(r)(3) and (8). Under § 122.21(r)(6), the owner or operator 

would indicate a request that the Director establish alternative BTA standards that are 

less stringent than § 125.94(c)(1) through (7). EPA recognizes the contribution of 

peaking units in serving peak electricity demands, and maintaining a reliable electricity 

grid. However, if peaking units are in standby mode for long periods relative to periods 

when they are generating electricity, the result is a capacity utilization of the cooling 

water intake that is greater than the capacity utilization of the generator. Significant 

periods of standby could contribute to a greater impact on aquatic life. While the 8 

percent capacity utilization is an industry standard that distinguishes those units making 

the greatest contribution to a smoothly functioning electricity grid, a Director may still 

determine that the impacts to aquatic life are significant enough to deny a request that 

BTA at that intake should be less stringent than (c)(1) to (c)(7). EPA anticipates the 

Director will have the information necessary to determine BTA in such circumstances 

based on the permit application requirements, including but not limited to an 

identification of the number of days the cooling water system is in operation, flow on 

those days, and seasonal changes in the operation of the system under § 122.21(r)(5) and 

the biological information under § 122.21(r)(4). 
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As discussed previously, the Director will determine the BTA for entrainment for 

low CUR units on a site-specific basis. EPA expects that many of the same factors 

discussed above – including the significance of the unit’s operation to the overall 

reliability of electric power in the area, the diversity of fuels available for the unit, and 

the impact of the costs of any potential entrainment requirements on the unit’s cooling 

water intake structure on overall reliability of electric power in the area – will be relevant 

in making site-specific BTA entrainment determinations for low CUR units. The 

Director may consider the factors at § 125.98(f)(3) when making these determinations for 

low CUR units, which includes grid reliability, among other factors. 

6. Monitoring 

The Director will review any impingement mortality and entrainment monitoring 

reports submitted by the facility to ensure ongoing compliance. EPA is shifting toward an 

electronic discharge monitoring report system, and many of the impingement mortality 

and entrainment standards can be incorporated into the discharge monitoring report itself, 

rather than requiring a separate report. Except for facilities choosing alternatives § 

125.94(c)(7) or (e)(2), the rule requires the), detailed biological monitoringdata collection

would only be included as part of the facility’s permit application submission and not for 

compliance purposes. The Director has the discretion to request additional information, 

including inspection of the facility, at § 125.95 (d) (i.e., permit application and supporting 

information requirements) and § 125.96 (c) (i.e., additional monitoring requirements). 

7. Nuclear Units 
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The rule includes a provision that permits the owner of a nuclear facility to 

demonstrate to the Director that compliance with the rule would result in a conflict with 

safety requirements for their facility. See § 125.94(f). EPA anticipates that this provision 

would be implemented as follows. Initially, the Director will draft a permit and will 

share the draft permit with the owner or operator of the nuclear facility. Upon reviewing 

the draft permit, the owner or operator will determine whether in their view a conflict 

with a safety requirement established by the Nuclear Regulatory Commission, the 

Department of Energy or the Naval Nuclear Propulsion Program exists. If a conflict 

exists, the owner or operator should communicate the conflict to the NRC, Department or 

Program and the Director. In all cases, whether a conflict exists or not, the Director 

should notify the NRC, Department or Program and the owner or operator of the facility 

that he or she wishes to informally confer regarding the permit. Such interactions should 

be scheduled, conducted and documented. Where a conflict is identified, the Director 

would make a site-specific BTA determination. 

F. What are Example Permit Conditions and Compliance Monitoring for 

Impingement Mortality? 

As previously discussed, the owner or operator must comply with BTA standards 

as soon as possiblepracticable on a schedule of requirements established by the Director. 

EPA did not specify dates by which the BTA standards for impingement mortality must 

be met because the specific method of compliance with the BTA standards for 

impingement mortality is, and should be, tied to the determination of BTA requirements 

for entrainment. Further discussion of this alignment of compliance deadlines is provided 
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in Section CA. Today’s final rule provides for several methods of compliance with the 

BTA for impingement mortality. This section discusses each of the methods for 

compliance, how they follow from the permit application requirements at § 122.21 (r), 

and any minimum monitoring and reporting requirements associated with each method. 

1. Closed-cycle recirculating system 

In this method of compliance, an existing facility must operate a closed-cycle 

recirculating system as defined at § 125.92.(c). The facility would indicate the choice to 

use this compliance method under § 122.21(r)(6) in its permit application. As specified in 

§ 122.21(r)(1), the facility would not need to submit (r)(7) or (r)(9) through (13).), if it 

exceeds 125 mgd AIF and these requirements are not waived by the Director. The 

information still required still at (r)(2) to (5) and (8) areis considerably less burdensome. 

The monitoring must be representative of normal operating conditions, and must include 

measuring cooling water withdrawals, make-up water, and blow downblowdown flows. 

The facility must monitor actual intake flows at a minimum frequency of daily, or may 

monitor the representative cycles of concentration at a minimum frequency of daily. 

These monitoring data would be used by the Director to determine that make-up and 

blowdown flows have been minimized. The owner or operator would submit these data 

with their existing DMR or equivalent state report. Facilities complying using closedcycle cooling are not subject to biological compliance monitoring unless otherwise 

specified by the Director (see § 125.96(c)). 
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2. Maximum through screen design velocity of 0.5 feetFeet per secondSecond 

Through-Screen Design Velocity

In this method of compliance, the facility must operate a cooling water intake 

structure that has a maximum design through-screen intake velocity of 0.5 feet per 

second. The facility must submit information under § 122.21(r) to the Director that 

demonstrates that the maximum design intake velocity as water passes through the 

structural components of a screen measured perpendicular to the screen mesh could not 

exceed 0.5 feet per second. The maximum velocity limit must be achieved under all 

conditions, including during minimum ambient source water surface elevations (based on 

BPJ using hydrological data) and during periods of maximum head loss across the 

screens or other devices during normal operation of the intake structure. 

EPA notes a cylindrical wedgewire screen, in general, is designed for 0.5 feet per 

second. In Phase II, EPA pre-approved wedgewire screens under very specific 

operational conditions. Today’s final rule simplifies the demonstration requirements for a 

facility employing cylindrical wedgewire screens to that of demonstrating the maximum 

design through-screen velocity is 0.5 feet per second. As another example, a facility may 

have pumping and piping constrictions that physically limit the design intake velocity to 

less than 0.5 feet per second. The Director may choose to establish permit conditions that 

address the physical limitations of the intake, such as requiring a pump be removed from 

service, or that only one of two (redundant) pumps may operate at any time. Facilities 

choosing to comply under this section do not have monitoring requirements under this 

section. 
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3. 0.5 feetFeet per secondSecond Through-screen Actual Velocity 

This method of compliance is similar to the maximum through screen design 

velocity of 0.5 feet per secondalternative discussed above, except that the intake’s 

maximum design velocity can exceed 0.5 fps, as long as the intake is operated such that 

the actual, measured velocity does not. As an example, a facility may have originally 

been constructed with a maximum design intake of 1.0 feet per second, but now, because 

it has retired generating capacity but not pumps, may only withdraw cooling water such 

that the actual intake velocity at the intake never exceeds 0.5 feet per second. This would 

constitute compliance with the impingement mortality standard. The maximum velocity 

must be achieved under all conditions, including during minimum ambient source water 

surface elevations (based on BPJ using hydrological data) and during periods of 

maximum head loss across the screens or other devices during normal operation of the 

intake structure. 

Monitoring the velocity at the screen face or immediately adjacent to the screen 

face must be conducted at a minimum frequency of daily. Monitoring of the approach 

velocity does not meet this requirement. However, in lieu of velocity monitoring at the 

screen face, the owner or operator may calculate the through-screen velocity using intake 

water flow, water depth, and the screen open areasarea. EPA is requiring this point of 

measurement to ensure that fish are actually able to swim away (not into an embayment 

from which they cannot escape) from the location within the intake structure at which 

they are most susceptible to being impinged. 
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Under today’s final rule, the Director may authorize the facility to exceed the low 

velocity standardcompliance alternative for brief periods for the purpose of maintaining 

the cooling water intake system, such as backwashing the screen face. In this compliance 

option, facilities are not subject to biological compliance monitoring unless otherwise 

specified by the Director (see § 125.96(c)). 

4. Existing Offshore Velocity Cap 

 In this method of compliance, facilities will submit information under § 122.21(r) 

that they operate an offshore velocity cap that meets the definition at § 125.92(v) and that 

was installed prior to the effective date of this rule. The definition of offshore velocity 

cap includes the requirement that the velocity cap be located a minimum of 850800 feet 

offshore. The velocity cap must include devices to exclude marine animals, such as bar 

screens. The velocity cap must be designed to change the direction of water withdraw 

from vertical to horizontal, thereby creating velocity patterns that can be sensed toand

trigger an avoidance response by fish and other aquatic organisms. Intake flow must be 

monitored at a minimum frequency of daily. This information will help to confirm the 

intended velocity patterns are created. In this compliance option, facilities are not subject 

to biological compliance monitoring unless otherwise specified by the Director (see § 

125.96(c)). 

EPA notes that facilities choosing to construct a velocity cap at an offshore 

location after the effective date of this rule willwould use compliance options § 

125.94(c)(6) (Systems of Technologies as the Site-specific BTA for Impingement 

Mortality) or § 125.94(c)(7) (Impingement Mortality Performance LimitStandard). 
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5. Modified Traveling Screens 

 In this method of compliance, a facility must first operate a modified traveling 

screen that meets the definition at § 125.92.(s). The definition identifies and requires 

those features of a traveling water screen that provide for an appropriate level of fish 

protection: collection buckets (or equivalent) to minimize turbulence to aquatic life; 

guard rails or barriers to prevent loss of fish from the collection system; screen panel 

materials such as smooth woven mesh, drilled mesh, molded mesh, or similar materials to 

protect fish from descaling; continuous or near-continuous rotation of screens and 

operation of collection equipment to recover impinged fish as soon as practical; low 

pressure wash or vacuum to remove collected organisms from the screens; fish handling 

and return with sufficient water flow to return fish directly to the source water in a 

manner that does not promote predation or the re-impingement of the fish, or a large 

vertical drop. EPA intends for this definition to generally include modified Ristroph 

screens, (including Geiger screens, Beaudrey WIP screens, and Hydrolox screens), dual 

flow screens, and rotary screens. 

Modified traveling screens with a fish return and handling system is the 

technology basis for the impingement mortality standard, therefore the EPA fully expects 

biological monitoring of a properly designed, built, and operated modified traveling 

screen would alwaysconsistently be able to meet the impingement mortality performance 

standard. If EPA were to simply set a performance standard based on the numeric 

limitperformance levels achievable by modified traveling screens, a facility would have 

to conduct continual biological monitoring to demonstrate compliance. A far more 
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efficient way to demonstrate compliance would be for facilities to optimize the operation 

of their technologies for their site-specific conditions and identify the conditions that 

distinguish proper operation at their facility. The optimized operation of the technology 

would be largely demonstrated through the biological monitoringdata collection and 

studies required in the permit application at § 122.21(r)(4) and (6)(i), including an 

impingement technology performance optimization study. Biological monitoringdata 

collection should follow the monitoringsampling protocols described in section 7section7

below. 

The optimized operation documented by the impingement technology 

performance optimization study will result in more than just meeting the impingement 

mortality performance standard, but ratherand results in a facility achieving the best 

possible performance.102 The biological monitoringdata collection and analysis in the 

impingement technology performance optimization study will identify the operating 

conditions that result in optimized performance, such as fish sluicing spray pressures, 

rotation speed and frequency of the screens, angle of the fish sluicing sprays, fish return 

trough water flows, and fish return trough location.103 The Director will then establish 

these operating conditions as permit conditions, along with an equipment inspection 

 

102 As demonstrated by the numerous studies included in the record for today’s final rule, many facilities 

are able to achieve less than 10 percent impingement mortality, a performance level comparable to the 

impingement mortality of closed-cycle cooling. Merely requiring facilities to achieve a numerical 

limitperformance standard through modified traveling screens creates disincentives to perform better. 103 EPA also requires the entrapment of organisms, as well as organisms that are carried over the screens, to 

be counted as impingement mortality. 
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condition to assure proper functioning of the technology. As long as the permit conditions 

are met, the EPA does not expect any biological compliance monitoring will be required, 

unless otherwise specified by the Director, for example, for the protection of shellfish or 

fragile species (see § 125.96(c)). Note that EPA does not intend for facilities to install 

closed-cycle cooling solely for the purpose of meeting the IM requirements. 

6. Systems of Technologies as the Site-specific BTA for Impingement Mortality 

In this method of compliance, a facility must demonstrate a system of 

technologies is employed that will meet the impingement mortality standard. This option 

will allow a facility the flexibility to choose the systems approach of technologies, 

management practices, and operational measures it will use to demonstrate compliance, 

including but not limited to flow reductions, intake location, behavioral deterrents, unit 

closures, seasonal operations, and newly installed velocity caps. Like the compliance 

option for modified traveling screens, the optimized operation of the system of 

technologies will be largely demonstrated through the biological monitoringdata 

collection and studies required in the permit application at § 122.21(r)(4) and (6)(ii). 

However, the analysis and studies for combining the performance of varied technologies 

is more involved. 

 If the system of technologies includes credit for reductions in the rate of 

impingement by the system, the impingement technology performance optimization study 

required at § 122.21(r)(6)(ii) will provide an estimate of those reductions including 

relevant supporting documentation. The estimated reductions in rate of impingement 

must be based on a comparison of yourthe facility’s system to a once-through cooling 
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system with a traveling screen whose point of withdrawal from the surface water source 

is located at the shoreline of the source water bodywaterbody. EPA expects Phase II 

facilities will use information already collected as part of their calculation baseline (69 

FR 41594, July 9, 2004). In addition, the study must include two years of biological 

monitoringdata collection demonstrating the rate of impingement resulting from the 

system. For this demonstration, monitoringdata collection must be conducted no less 

frequently than monthly. The Director may establish more frequent monitoringdata 

collection or a longer period of study. 

 If the system of technologies includes credit for reductions in impingement 

mortality already obtained at the facility, the study must include two years of monthly 

biological monitoringdata collection demonstrating the level of impingement mortality 

the optimized system achieves. Biological monitoringdata collection must be 

representative of the impingement and the impingement mortality at the intakes and 

should follow the monitoringsampling protocols described in section 7 below. The 

impingement technology performance optimization study must provide a description of 

any sampling or monitoring approach used in measuring impingement mortality, 

including a taxonomic identification to the lowest taxon possible of all organisms to be 

monitoredsampled; the method in which naturally moribund organisms are identified and 

taken into account; and the method in which mortality due to holding times is taken into 

account. In addition, the study must describe how the location of the cooling water intake 

structure in the water bodywaterbody and the water column are accounted for in the 

points of monitoringsampling locations. EPA requires the entrapment of organisms, as 
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well as organisms that are carried over the screen, to be counted as impingement 

mortality. 

 If the system of technologies specifically includes flow reduction to reduce 

impingement, the impingement technology performance optimization study must include 

two years of intake flows, measured daily, as part of the demonstration, and must 

describe the extent to which flow reductions are seasonal or intermittent. The rule 

clarifies that credit for flow reductions must result from actual reductions in flow, 

therefore the AIF will be used as a point of comparison, and not the DIF. The study must 

document how the flow reduction results in reduced impingement, and how the reduction 

in impingement has reduced the site-specific impingement mortality. Today’s final rule at 

§ 125.98(f)(3)(iii) further clarifies that credit in reduced impingement or impingement 

mortality resulting from unit closures will be valid for a period of 10 years.104 This is also 

reflected in permit application requirements for an owner or operator planning to retire 

the facility in the current permit term at 40 CFR 122.21 (r)(1)(ii)(F), or in the following 

permit cycle at 40 CFR 122.21 (r)(1)(ii)(G). 

 The Director must determine the system of technologies, management practices, 

and operational measures that is the best technology available for impingement reduction 

at the site. As the basis for the Director’s determination, the facility must demonstrate

 

104 Because a permit may be administratively continued or may not be issued every 5 years, EPA has 

specified 10 years rather than two permit cycles to avoid facilities from taking credit for a unit closure that 

potentially occurred decades prior. 
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that the system of technology has been optimized to minimize impingement mortality of 

all non-fragile species. In addition to the impingement technology performance 

optimization study, the Director may also use the biological source water characterization 

and/or the entrainment characterization studies in the permit application. EPA expects the 

Director’s decision will be informed by comparing the impingement mortality data under 

§ 122.21(r)(6)(ii) to the impingement mortality limitperformance standard that would 

otherwise apply under § 125.94(c)(7). 

In addition, the impingement technology performance optimization study requires 

documentation of the percent impingement mortality reflecting optimized operation of 

the total system of technologies, operational measures, and best management practices 

and all supporting calculations. The following example illustrates how these provisions 

will adjust for flow, location, and other technologies in demonstrating the IM 

performance for a system of technologies. 

The example uses values that simplify the calculations to better illustrate the 

adjustments, and are not intended to reflect values that EPA expects at any facility. To 

simplify the example further, the facility has only fish and does not have shellfish in its 

source waters. EPA has chosen a hypothetical facility that examined each change in a 

separate study.105 The hypothetical facility intake is located at a submerged offshore 

 

105 EPA recognizes that facilities often examine the combined effect of two or more technologies (e.g., 

deterrents and offshore location) within a single study. In applying these provisions, the facility could use 

the outcomes associated with the combined performance of multiple technologies, but this would result in 

permit conditions that would also be combined. 
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location, has an acoustical deterrent, and installed variable speed drives. For the purposes 

of this example, the facility has completed sampling at the forebay for two years as part 

of § 122.21(r)(4) and (6). During the most recent 12 months, the counts of non-fragile 

species totals 40,000 impinged fish. During the 24-hour holding period following each 

monthly sample collection, the total fish that died were counted, for a total of 12,000 

dead fish for the preceding 12 months. The facility then calculated the average annual IM 

for the preceding 12 months at 30 percent as follows: 

 % IM = (impinged fish that are killed) x 100 

 (total number of impinged fish) 

 = (12,000) / (40,000) x100 

 = 30 % 

To adjust the observed percent IM for a submerged offshore location and 

acoustical deterrent, the facility first extracts information from its previously conducted 

studies related to performance and calculation baseline. Alternatively, the facility could 

conduct a performance study during the same two year period in which it conducts its 

biological monitoringdata collection as part of the permit application requirements at § 

122.21(r). For the submerged offshore location adjustment, fish density and flow data 

show the offshore location reduces the rate of impingement for all species by 4,000 fish 

annually. For the acoustical deterrent, performance data show a reduction in the rate of 

impingement of fish by 11,000 organisms annually. For purposes of this example, assume 

none of the 15,000 fish are assumed to contribute to further mortality; in other words, all 

of the fish that avoided impingement in the first place survive. Therefore, the facility has 

reduced impingement by 15,000 fish (i.e., sum of both submerged offshore location and 
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acoustical deterrent). The facility then takes credit for this reduction by adding the 

forgone impingement to the denominator of the percent IM calculations as follows: 

% IM = (impinged fish that are killed) x 100 

 (total number of impinged fish) 

 = (12,000) / (40,000+15,000) x100 

 = 22 % 

In summary, calculating percent IM at the forebay yields a 30 percent IM, and 

then applying the performance for existing technologies shows the effective percent IM is 

actually 22 percent. Next, to adjust for the variable speed drives, the facility has 

determined from flow monitoring that the volume of cooling water flow has been reduced 

by 11 percent. In this example, assume the flow reduction does not vary considerably 

each month. The volume of reduced flow multiplied by the density of fish near the intake 

is calculated each month for 12 months, and the facility projects that the reduced flow 

excludes an additional 8,000 fish from impingement each year. Then the facility would 

apply the reduction in annual counts of impinged fish to the denominator, as follows: 

% IM = (impinged fish that are killed) x 100 

 (total number of impinged fish) 

 = (12,000) / (40,000+15,000+8,000) x100 

 = 19% 

Thus, the facility’s site-specific system of technologies including optimized 

operation of acoustical deterrents has a total system performance of 19 percent annual 

impingement mortality. This example is intended to illustrate how facilities would obtain 

credit for existing technologies in a systems approach. While this example includes 

acoustical deterrents, it does not imply that acoustical deterrents are an appropriate 
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technology for all facilities. EPA expects a facility will use the required two yearsyears’

worth of monthly biological monitoringdata collection and studies to conduct a similar 

analysis for each month. The minimum required monitoringdata collection and studies 

will result in annual average performance calculations for 12 consecutive months. The 

facility will use this information as part of its demonstration to the Director. 

If the Director determines the system of technologies, management practices, and 

operational measures is the best technology available for impingement reduction at the 

site, the Director will establish specific operating conditions as permit conditions, along 

with appropriate equipment inspection conditions to assure proper functioning of each 

technology. For example, a system with acoustical deterrents would likely have permit 

conditions related to frequency of tones, volume, location, and frequency of operation of 

the acoustical deterrents. The Director will also establish monitoring requirements for 

intake flow and velocity where such measures are an important part of the system of 

technologies, such as the case of variable speed drives. For example, a system that 

includes seasonal flow reductions would likely have permit conditions for flow 

monitoring. As long as the permit conditions are met, the EPA does not expect any 

biological compliance monitoring will be required, unless otherwise specified by the 

Director (see § 125.96(c)). 

7. Impingement Mortality Performance Standard 

In this method of compliance, facilities are required to monitor to demonstrate 

compliance with the impingement mortality performance limitstandard at § 125.94(c)(7) 

by demonstrating an annuala 12-month average mortality of 2524 percent or less. The 
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facility is required to monitor at a minimum frequency of monthly, unless a greater 

frequency is specified by the Director. For each monitoring event, the facility would 

determine the number of non-fragile organisms that are collected or retained on sieve 

with a maximum spacing of 0.56 inches (i.e., that are impinged [I]), and the number that 

die during after impingement (i.e., impingement mortality [IM]). The facility must 

establish a post-impingement holding period of 18 to 96 hours otherwise specified by the 

Director. Under the definition at § 125.92,(b), all life stages of fish and shellfish excludes 

specified nuisance species from the totals for both impingement and impingement 

mortality. Also, as defined at § 125.92(bq), latent mortality 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 may be due to stresses that

include but are not limited to temperature change, physical stresses, and chemical 

stresses. The manner in which latent mortality is counted must be identified in the 

Entrainment Characterization Study at § 122.21(r)(9), and must also be counted in the 

Impingement mortality performance standard at § 125.94(c)(7). Fish that are included in 

any carryover from a traveling screen or removed from a screen as part of debris removal 

must be counted as impingement mortality. Fish that are entrapped by the cooling water 

intake system must be counted as impingement mortality. 

The annual12-month average of impingement mortality is calculated as the sum 

of total impingement mortality over 12 months divided by the sum of the total 

impingement mortality over the same 12 months, as shown by the following equation: 
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ܯܫ൬ ൌ ܯܫ	%

ܫ ൰ ൈ 	100

Note that this equation would be applicable to calculating the annual average for 

the previous 12 months. Although facilities will be conducting biological monitoring 

monthly (or more frequently) and reporting that data in their discharge monitoring 

reports, facilities are not required to meet a monthly impingement mortality 

limit.performance standard. Therefore, in this equation, IM is the sum of all impingement 

mortality over the course of the previous 12 months, and I is the sum of all impinged fish 

for the previous 12 months. If the facility’s calculated annual average percentage 

impingement mortality is less than the annual12-month average limitationperformance 

standard, it will be deemed to be in compliance with the annual12-month average 

limitationperformance standard. 

 In establishing the 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. 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. 

The ideal point to measure impingement mortality is the location where 

organisms are returned to the water bodywaterbody. However, for ease of sampling and 
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access, EPA envisions that most facilities will collect samples from the fish return 

system(s) at some point before the fish return discharge point. According to the studies in 

EPA’s database, EPA envisions that facilities will either (1) divert some or all of the flow 

from the fish return into a fish collection and holding area, or (2) place a net or basket 

fitted with 3/8-inch mesh spacing in the fish return and collect and transfer the retained 

organisms to a holding tank. While nearly all studies in the record report the use of 3/8-

inch mesh spacing, as discussed below, the final rule allows the use of other sieve and 

mesh spacings with a 0.56 inch maximum opening. A facility will handle the organisms 

in the collection device as little as possible and transfer them to a holding area with 

conditions as close as practicable to the source water. The facility will count the number 

of organisms in the holding area and subsequently hold the sample using proper 

technique106 to maintain the health of the collected organisms.107 At a period of 18 to 96 

hours after the initial collection, the facility will count the number of dead organisms and 

determine the percentage of organisms that died in comparison to the total number of 

organisms measured initially. Any organisms not collected by the fish handling and 

return system, such as entrapped organisms, organisms in the carryover of a traveling 

screen, or organisms collected by a high-pressure wash and sent to debris bins, will be 

 

106 EPA recognizes that at present, there are no standard methods for conducting impingement and 

entrainment studies and that there can be variability in designing a sampling plan between sites. However, 

some elements should be incorporated into any sampling plan, as outlined in DCN 10-6708. 

107 Facilities that divert the flow directly would similarly pass the flow through a net or debris basket fitted 

with 3/8-inch mesh spacing or would count only organisms that would have been collected with such a 

basket or net. 
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counted as 100 percent impingement mortality. The facility will keep records of this 

information and compare its result to the impingement mortality performance standard at 

§ 125.94(c)(7). 

 As explained in Section VI, the impingement mortality restrictions in the final 

rule are based on the operation of a modified traveling screen with a fish return. Because 

EPA wants to ensure that a facility’s monitoring plan is consistent with the technical 

basis for today’s requirements, 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.108 In doing so, facilities would retain (and therefore count) only 

organisms that would have been impinged on a 3/8” mesh screen, which was the 

technological basis used for developing the impingement mortality limitperformance 

standard.

109 Facilities could 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. For example, a facility that uses a fine-mesh screen of 0.5 mm or diverts 

 

108 For a discussion of how EPA has changed its view of screen mesh size, see sectionSection III of the 

proposed rule (76 FR 22188, April 20, 2011). EPA recognizes that smaller organisms that previously would 

have passed through a screen and been entrained might be “converted” by a fine mesh screen to an 

impinged organism; because organisms size would affect the rate of mortality, EPA has chosen not to rely 

on definitions of impingement and entrainment based on a physical process, but instead to define 

impingement mortality and entrainment mortality based on organisms sizes. 

109 EPA’s analysis of impingement survival rates is based on data from facilities with 3/8” mesh screens; 

these limitsthe performance standard may be applied differently at facilities with smaller mesh size. 

Therefore, these limitsstandards do not provide a disincentive to facilities from using finer-meshed screens 

(i.e., screens with a mesh opening smaller than 3/8 inch) on their traveling screens. As long as the 

organisms that are large enough to have been impinged on a coarse mesh screen achieve the required 

survival rates, the facility will be considered to meet the impingement mortality requirements. 
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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. 

EPA further expects the impingement mortality restrictions could be applied to other fish 

protection technologies and provides a compliance route for future technologies that are 

better performing. 

In today’s rule, EPA is including provisions for reduced biological monitoring. 

EPA determined that monthly monitoring at a minimum is appropriate for at least the first 

full permit term. In permit terms subsequent to the first permit issued under today’s rule, 

the owner or operator may request the Director to reduce monitoring requirements under 

§ 125.95(c). EPA expects the Director would reduce monitoring requirements as 

appropriate., if the facility demonstrates that its operational and biological conditions 

have remained the same. Given that the source water bodywaterbody may change over 

time (including hosting different or increased numbers of individuals or species), the 

biological characterization required at § 122.21(r)(4) including two years of data serves 

to alert interested parties as to the status of the water bodywaterbody and any changes in 

the biology of the water bodywaterbody. Under the compliance option (7) impingement 

mortality performance standard, EPA expects that as new technologies are successfully 

demonstrated, in subsequent permits facilities would request less frequent monitoring, or 

be able to incorporate such technologies in a permit application choosing a § 

125.94(c)(6), system of technologies, demonstration. Once the Director has determined 

the technology is fully demonstrated for that site, the facility would therefore reduce their 

biological monitoringdata collection to the minimum required by the permit application 
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at § 122.21(r) and any monitoring the Director determines to be appropriate for verifying 

permit operating conditions. 

88. Additional Measures 

Sections § 125.94(c)(8) and (9) provide the Director discretion to require 

additional measures to protect shellfish and fragile species. An example of shellfish 

protection measures is a barrier net, including seasonal deployment of such nets. An 

example of additional protection measures for fragile species is an acoustical deterrent 

system. 

9. Summary 

The following Exhibit VIII-4 summarizes the monitoring requirements for 

impingement mortality by compliance approach alternative. The Director has the 

discretion to require additional monitoring under § 125.96(c) and (d). Since all permits 

must have requirements for visual inspections, these are not included in the exhibit. 

Exhibit VIII-4. Summary of monitoring requirements for impingement mortality 

Compliance approach Type of monitoring Frequency 

Closed-cycle recirculating 

system 

Intake, makeup and blowdown 

flows (or cycles of concentration) 

Daily 

Velocity (DIF) None None 

Velocity (AIF) Velocity (measured or calculated 

from flow) 

Daily 

Velocity cap Intake flow Daily 

Modified traveling 

screens 

TBDa

 TBDa

Systems of Technologies TBDb

 TBDb
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Impingement mortality 

performance standard 

Biological monitoring Monthly 

a Monitoring requirements may vary, depending on the permit-specific operating conditions. 

b The monitoring requirements are based on the technologies employed. For example, seasonal flow reduction would require 

flow monitoring. 

G. What Monitoring is Required for Entrainment? 

In establishingWhere the Director establishes entrainment controls, the Director is 

required to establish monitoring requirements. The final rule requires that the permit 

application studies at § 122.21(r) be submitted for each permit renewal. For facilities that 

withdraw 125 mgd AIF, EPA expects that the Director will use these studies, including 

the Source Water Baseline Biological Characterization Data at § 122.21(r)(4) and the 

Entrainment Characterization Study at § 122.21(r)(9), as a basis for any monitoring 

requirements for entrainment. To facilitate the determination of entrainment requirements 

for facilities below 125 mgd AIF, a Director may require the owner or operator to submit 

some or all of the study requirements at § 122.21(r)(9) through (13) or variations thereof. 

The Director may require additional monitoring necessary to demonstrate compliance 

with § 125.94(d), additional measures to protect Federally-listed endangered and 

threatened species and designated critical habitat requirements under § 125.94(g), interim 

standards under § 125.94 (g(h), and any more stringent standards under § 125.94(fi). 

Under § 125.96(d), existing facilities with new units are required to conduct 

compliance monitoring to demonstrate flow reductions consistent with the requirements 

of § 125.94(e)(1), or equivalent impingement and entrainment reductions. The Director 

may establish flow monitoring or monitoring of cycles of concentration as discussed in 
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Section F. Such flowsmeasures will be used to document that the facility has minimized 

make-up and blowdown flows. 

For facilities required to demonstrate flow reductions consistent with the 

requirements ofcomplying under § 125.94(e)(2), the frequency of monitoring mustwill be 

dailydetermined by the Director and be representative of that day’s maximum operating 

conditions. will vary depending on the facility’s chosen method of compliance. 

To meet requirements under § 125.94(e)(2), facilities must measure AIF to 

establish a site-specific baseline without any new technologies or employing additional 

operational measures. The facility must also measure the density of entrainable organisms 

(ED) at a proximity to the intake that is representative of the entrainable organisms 

present without the cooling water intake structure. Samples will be collected over a 24-

hour period to monitor each species as required by the Director. Samples will be 

collected no less than biweekly during the primary period of reproduction, larval 

recruitment, and peak abundance identified during the source water baseline 

characterizationSource Water Baseline Biological Characterization Data required under § 

122.21(r)(4). Samples will be representative of the cooling water intake when the 

structure is in operation. In addition, sufficient samples must be collected to allow for 

calculation of annual12-month average entrainment levels. The sampling will measure 

the total count of entrainable organisms or density of organisms, unless the Director 

approves of a different metric for such measurements. If the abundance varies seasonally, 

the Director may require several measurements of entrainment through the year, from 

which an annuala 12-month average can be calculated. 
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For the purpose of today’s rule, entrainable is defined as any organism that passes 

through a sieve with a maximum opening of 0.56 inches. As discussed in Section VI, this 

would avoid any confusion as to which organisms are subject to which standards (i.e., 

requirements for IM or requirements for E). The regulation specifies that the sieve used 

for calculating impingement must be the same sieve used for calculating entrainment, so 

all organisms are counted.accounted for. Facilities can also monitor the latent 

entrainment mortality in front of the intake structure. Entrainable organisms passing 

through the cooling water intake structure are to be counted as 100 percent entrainment 

mortality unless the facility demonstrates to the approval of the Director that the 

mortality for each species of concern is less than 100 percent. 

In addition, facilities must monitor the AIF for each intake. The AIF must be 

measured at the same time as the samples of entrainable organisms are collected. 

The following equation illustrates how to calculate a baseline level of entrainment 

(EB): 

EB = ED × AIF

Performance commensurate with a closed-cycle coolingrecirculating system 

(EBTAECCRS) can therefore be determined by reducing EB by the percentage of flow 

reduced through the use of a closed-cycle cooling system. For example, a facility 

withdrawing make-up water from a freshwater source (as described above, would achieve 

a reduction of 97.5 percent) will calculate its performance as follows: 

EBTAECCRS = (EB) × (100 – 97.5) ÷ 100 
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The resulting value, EBTAECCRS, is the required level of entrainment performance 

(as measured by entrainment mortality). The facility could implement any combination of 

flow reduction, technologies, and operational measures to meet the required level of 

entrainment performance. For example, a facility withdraws 200 mgd AIF from a 

freshwater river. The annual average entrainment density in the proximity of the intake 

structure is 6,400 organisms per 100 cubic meters withdrawn. 

EB = ED × AIF

6,400 organisms/100m3

 × (100m3 / 26,417 gallons) × 200,000,000 gallons per day 

= 48 × 106

 organisms per day 

The maximum entrainment mortality for a closed-cycle cooling system is thus 

EBTAECCRS = (EB) × (100 – 97.5) ÷ 100 

= (48 × 106 organisms per day) × (100 – 97.5) ÷ 100 

= 1.2 × 106

 organisms per day. 

The minimum required level of performance for demonstrating entrainment 

mortality at a comparable level (EC) to a closed-cycle cooling system is the level 

corresponding to 90 percent110 of the reduction that a facility with a closed-cycle cooling 

system could achieve: 

EC = (EB) × (100 – (97.5 × .9)) ÷ 100 

 

110 The 90 percent metric is required in Phase I, and adopted here because new units are subject to 

requirements similar to the Phase I requirements. Phase I, at 40 CFR 125.86 specifies, “reduced both 

impingement mortality and entrainment of all life stages of fish and shellfish to 90 percent or greater of the 

reduction that would be achieved through § 125.84(b)(1) and (2).” 
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= (48 × 106

 organisms per day) × (100 – (97.5 x .9)) ÷ 100 

= 5.988 × 106 organisms per day. 

The Director may require additional monitoring necessary to demonstrate 

compliance with § 125.94(d), endangered species requirements under § 125.94(g), 

interim standards under § 125.94 (gh), and any more stringent standards under § 

125.94(hi). 

In addition, all facilities will either conduct visual inspections or employ remote 

monitoring devices when the cooling water intake structure is in operation. The facility 

will conduct such inspections at least weekly to ensure that any technologies installed to 

comply with § 125.94 are maintained and operated to ensure that they will continue to 

function as designed. 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 § 

125.96(e). 

H. What Reports Am I Be Required To Submit? 

1. Status Reports 

 If the Director establishes a compliance schedule, the Director will also establish 

any status reporting requirements. These reports may include updates on biological 

monitoring, technology testing results, construction schedules, or other appropriate topics 

and serve as milestones for the facility and the Director to evaluate the progress of the 

facility in meeting BTA. See §§ 125.94(b) and (d) and 125.97(b). 
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2. Monitoring Reports 

The required reports for monitoring activities are similar to requirements that are 

already in NPDES permits for effluent discharges. EPA expects such reports to be 

included with the Discharge Monitoring Reports (DMRs) or equivalent state reports. 

Facilities would report any monitoring, demonstration, and other information required by 

the permit sufficient to determine compliance with the permit requirements established 

under § 125.94, as well as any other monitoring requirements specified in the permit. See 

40 CFR 125.7997(a). 

Entrainment requirements will be determined on a site-specific basis by the 

Director. For facilities that are required to install entrainment controls, EPA expects that 

these facilities would generally conduct ongoing flow (or other) monitoring as 

verification that entrainment has been reduced. See § 125.96(db) and (c). However, the 

Director may require facilities to report entrainment monitoring and analysis, including: 

 The compliance measurement location. 

 A description of the flow monitoring procedure. 

 Documentation of flow reductions. 

 Any other monitoring requirements specified in the permit. 

The report must include any monitoring and analysis required as part of additional 

measures for threatened and endangered species, shellfish, and/or fragile species as 

established by the Director. Further, your report will include documentation of cooling 

water that is process water, gray water, waste water, reclaimed water, or other water 
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reused as cooling water in lieu of water obtained by an intake. The Director will evaluate 

these reports for compliance with permit requirements as appropriate. 

3. Annual Certifications 

Today’s rule requires a facility to submit an annual certification statement signed 

by the responsible corporate officer. See § 125.97(c). In most cases, the statement would 

indicate the information from the previous statement is still pertinent. If modifications 

were made to the facility that impacts cooling water withdrawals or operation of the 

cooling water intake structures, the statement would indicate such, and the facility would 

submit revisions to the information required in their permit application at § 122.21(r). 

4. Other Reporting 

 In addition, EPA notes that supplemental reporting may be required under the 

ESA as part of any incidental take statement or permit (50 CFR 402.14(i)) or a 

Sectionsection 10 permit (50 CFR 222.307) that is issued by the United States Fish and 

Wildlife Service or the National Marine Fisheries Service to ensure compliance with the 

Endangered Species Act. 

I. What Records WouldWill I Be Required to Keep? 

As described at § 125.97(d), facilities are required to keep all permit applications, 

status, monitoring, and annual reports and related supporting information and materials at 

least until the subsequent permit is issued. Facilities might wish to keep records for a 

longer period to maintain a complete regulatory history of the facility. For example, 

existing source water biological studies submitted with a facility’s permit application 

could contain data that has been collected in the past 10 or more years. When the Director 
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has approved a request for reduced information collection in the permit application, the 

rule requires that records of submissions that are part of a previous permit application be 

kept until the subsequent permit is issued. See § 125.95(e). Records supporting the BTA 

determination for entrainment must be kept until such time as the Director revises the 

determination. The Director may establish additional record-keeping requirements in the 

permit, such as additional records documenting compliance monitoring, data collection, 

or more frequent reports. 

Facilities must also keep records of all data used to complete the permit 

application and show compliance with the requirements of § 125.94, any supplemental 

information developed under § 125.95, and any compliance monitoring data submitted 

under § 125.96. The Director may require that these records be kept for a longer period. 

J. What Are the Respective Federal, State, and Tribal Roles? 

Today’s final rule affects authorized State and Tribal NPDES permit programs. 

Under 40 CFR 123.62(e), any existing approved section 402 permitting program must be 

revised to be consistent with new program requirements within one year from the date of 

this promulgation, unless the NPDES-authorized State or Tribe must amend or enact a 

statute to make the required revisions. If a State or Tribe must amend or enact a statute to 

conform to today’s final rule, the revision must be made within two years of this 

promulgation. States and Tribes seeking new EPA authorization to implement the 

NPDES program must comply with the requirements when authorization is approved. 

This final regulation does not alter State authority under section 510 of the CWA. 
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In addition to updating their programs to be consistent with today’s final rule, 

States and Tribes authorized to implement the NPDES program are required under 

NPDES State program requirements to implement the cooling water intake structure 

requirements of subpart J following promulgation of the final regulations. The permit 

requirements in this final rule must be implemented upon the first issuance or reissuance 

of permits following promulgation. Duties of an authorized State or Tribe under this 

regulation are described throughout this section and include reviewing permit application 

materials, determining appropriate requirements, reviewing monitoring and reporting 

data, and assessing whether a facility is complying with the final rule’s requirements. 

EPA recognizes that some States have invested considerable effort in developing 

and implementing section 316(b) permits. This final regulation at § 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 § 122.21(r). 

EPA will implement these requirements where States or Tribes are not authorized 

to implement the NPDES program. 

K. Permits for Protection of Endangered and Threatened Species and 

Designated Critical Habitat 

1. Existing Facilities Are Subject to Requirements under section 9 of the 

Endangered Species Act 

 The ESA imposes duties not just on Federal agencies but also on other entities. 

Section 9 of the ESA specifically provides that it is unlawful for any person to “take” any 
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endangered species of fish or wildlife except under defined circumstances. The Services 

(National Marine Fisheries Service or U.S. Fish and Wildlife Service) may provide an 

exemption to the prohibition on take in one of two ways. Take may be permitted under 

section 10 of the ESA (16 U.S.C. § 1539) or the Services may provide an exemption for 

take that is incidental to otherwise legal activity through a statement that is included with 

the Services’ biological opinion developed during Federal agency consultation. (16 

U.S.C. 1536(o)) The incidental take statement specifies the terms and conditions 

necessary to implement reasonable and prudent measures which minimize incidental 

take. 

 Nothing in today’s rule changes the existing, independent obligations of the 

facilities subject to this rule under section 9 of the ESA. Unless exempted by an 

incidental take statement or section 10 permit, facilities have been prohibited from taking 

(for example, harming or killing) endangered species of fish or wildlife. In order to obtain 

a section 10 permit, the facility would be required to develop a Habitat Conservation Plan 

(HCP), which is a mandatory component of an incidental take permit application. The 

HCP must specify the anticipated effects of the proposed taking, how those impacts will 

be minimized or mitigated, the alternative actions to the taking that the applicant 

considered, the reasons for not utilizing those alternatives, and other necessary or 

appropriate measures that the Secretary may require. 
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2. EPA’s NPDES permitting regulations at 40 CFR 122.49 lists Consultation Under 

Section 7 of the ESA 

 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 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. . . .” 16 U.S.C. (ESA), 16 U.S.C. 1531 et seq, as one of the other 1535(a)(2). In 

the case of any Federal agency action subject to the ESA that may affect listed species or 

critical habitat, the Federal agency must consult with the concerned offices with 

responsibilities under the ESA, specifically NMFS and/or FWS. 50 CFR 402.14(a). 

 In July 2012, EPA began informal consultation with the NMFS about the 

proposed section 316(b) regulations. In October 2012, EPA began informal consultation 

with the FWS. EPA prepared a draft biological evaluation of the effects of this rule on 

threatened and endangered species and in it concluded that the rule was not likely to 

adversely affect listed species or designated critical habitat. EPA was unable to obtain the 

Services’ concurrence on EPA’s “not likely to adversely affect” finding. In June 2013, 

EPA requested formal consultation with the Services under the Endangered Species Act 

and with that request submitted a final biological evaluation to the Services. EPA 

completed consultations with the Services and has included the Services’ biological 

opinion and associated documents in the record for this rulemaking. 
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 Among the organisms potentially subject to impingement and entrainment at 

cooling water intake structures are those that are listed as threatened and endangered. In 

addition to impinging or entraining threatened and endangered species, operation of 

CWISs may also adversely affect their critical habitat. Today’s rule includes a number of 

provisions specifically designed to address incidental take of all federally-listed 

threatened and endangered species and to insure that the rule is not likely to jeopardize 

the continued existence of listed species or result in the destruction or adverse 

modification of critical habitat. These provisions are described below. 

 The regulatory model adopted by EPA in the Phase I rule and later in the 

subsequently-withdrawn Phase II rule for large existing power producing facilities 

provided a structure to address and minimize adverse impacts to threatened and 

endangered species. EPA’s approach required that facilities subject to the 316(b) rules, at 

the permit application stage of the permitting process must, among other things, identify 

threatened and endangered species that might be subject to impingement and entrainment 

in order to ensure that the permitting authority would have the requisite information on 

which to make a decision about the need for controls to protect threatened and 

endangered species. See 40 C.F.R. § 122.21(r)(4). 

 The Phase I and Phase II regulations specifically authorized the permit writer 

(referred to as the “Director” in EPA’s permitting regulations) to adopt measures 

designed to protect threatened and endangered species. Thus, for example, EPA’s Phase 

I regulations for cooling water intake structures at new facilities require that, under one of 

the compliance options, an owner or operator must select and implement impingement 
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and entrainment minimization measures “if there are threatened or endangered or 

otherwise protected Federal, State or Tribal species.” Moreover, the permit writer may 

require additional impingement and entrainment reduction measures if the permit writer 

determines that the facility after meeting the required performance standard would “still 

contribute unacceptable stress to the protected species, critical habitat of those species or 

species of concern.” 40 C.F.R. 125.84(b)(4) & (5). 

 The Phase II regulation continued the general approach followed in the Phase I 

regulation for protection of threatened and endangered species. Permit applicants needed 

to submit the same information on threatened and endangered species required in the 

Phase I rule. In addition, building on the earlier information requirements, the regulation 

also would have required facilities selecting and implementing certain of the alternative 

BTA compliance measures to submit a Comprehensive Demonstration Study that, among 

other things, characterized impingement and entrainment at the facility. Further, the rule 

would have required a facility to submit an Impingement Mortality and/or Entrainment 

Characterization Study that included taxonomic identification, characterization and 

documentation of current impingement mortality and entrainment of all life stages of fish, 

shellfish and any species protected under Federal, State or Tribal law (including 

threatened or endangered species). 69 FR 41687-88, July 9, 2004. In addition, the Phase 

I and II rules included a requirement for the facility to include in their permit application 

documentation of any public participation or consultation with Federal or State agencies 

on impacts of their cooling water intake structure on threatened and endangered species. 

The regulation then would have required the permit writer to determine appropriate 
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permit requirements and conditions. EPA noted that its existing NPDES permitting 

regulations reference a number of Federal laws that might apply to theFederally-issued 

NPDES permits, including the Endangered Species Act. 69 FR 41643-44, July 9, 2004. 

 Threatened and endangered species were important considerations in the proposal 

to today’s rule and were of particular concern to the EPA. The preamble to the proposal 

reflects at a number of points that, in looking at the benefits of different regulatory 

options, EPA attempted to assess the benefits to threatened and endangered species. See 

76 FR 22174, 22197, 22207. The proposal also noted the importance of obtaining 

information for the permit writer about potential entrainment reductions. Thus, the 

proposal would have required certain facilities to develop and submit with their permit 

application detailed information on their operations as well as an engineering study of the 

technical feasibility and incremental costs of candidate entrainment mortality control 

technologies and a detailed discussion of the magnitude of non-water quality benefits. 

EPA proposed that some facilities would need to submit an Entrainment Characterization 

Study that included an entrainment mortality data collection plan that would indicate, at a 

minimum, taxonomic identification, latent mortality identification, documentation of all 

methods, and quality assurance/quality control procedures or sampling and data analysis 

appropriate for a quantitative survey. Under the proposal, EPA would also have required 

peer review of the entrainment mortality data collection plan. Peer reviewers would be 

selected in consultation with the Director who may consult with EPA and Federal, State, 

and Tribal fish and wildlife management agencies with responsibility for fish and wildlife 

potentially affected by the cooling water intake structure(s). Further, facilities with 
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greater than 125 mgd AIF would complete an entrainment study. The entrainment study 

could include information already collected to meet the Phase II requirements at § 

122.21(r)(2)-(r)(4) before those requirements were suspended. 

EPA and the Services have completed consultations on the rule. EPA has received 

the final biological opinion and associated documents from the U.S. Fish and Wildlife 

Service and the U.S. National Marine Fisheries Service and has included them in the 

record for the rule. The Services have concluded that the rule is not likely to jeopardize 

the continued existence of listed species or result in the destruction or adverse 

modification of designated critical habitat. 

3. Final Rule Provisions Related to Threatened and Endangered Species 

 As noted previously, establishing standards for cooling water intake structures to 

minimize impingement and entrainment of all aquatic organisms will promote and 

enhance protection of T&E species. In addition, the rule contains a number of provisions 

that specifically concern T&E species; these provisions were developed in light of EPA’s 

consultation with the Services and were established by EPA to insure that this rule is not 

likely to jeopardize listed species or result in the destruction or adverse modification of 

designated critical habitat. To be clear, the ESA provisions of the rule extend to all listed 

T&E species, not just fish and shellfish. 

 The treatment of T&E species in today’s rule follows directly from the Agency’s 

longstanding approach as well as from EPA’s proposed 2011 rule which indicated the 

EPA’s intention to address protection of T&E species. The rule adopts the identical 

approach followed in the Phase I and II rules, while adding some refinements to that 
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earlier model which EPA discussed in the proposed rule. First, it adopts the proposed 

requirements that insure an adequate information base is submitted to the permit writer. 

As was the case with the Phase I and withdrawn Phase II rule, apprising the permit writer 

of the presence and extent of T&E species at a facility’s intake continues to be an 

important element of the permit application requirements for existing facilities. While 

retaining the existing permit application requirement of 40 C.F.R. § 122.21(r), EPA has 

included in today’s rule a provision at § 125.95(f) that requires a facility in its permit 

application to identify all Federally-listed threatened and endangered species and 

designated critical habitat that are or may be present in the action area. The action area 

can generally be considered the area in the vicinity of the cooling water intake structure. 

The evaluation is to be based on information readily available to the facility at the time of 

the permit application. In addition, the rule requires the largest withdrawing facilities to 

provide taxonomic identification of species in the vicinity of the intake, thus providing a 

mechanism for facilities to determine more accurately their potential impact on protected 

species. 

 The rule requires that the Director transmit all permit applications to the Services 

upon receipt. The rule provides the Services with 60 days to review the permit 

application. This 60 day review takes place prior to the public notice of the State or 

Tribe’s draft or proposed permit. EPA expects that the Services will respond within 60 

days and provide to the Director (1) any corrections to the list of Federally-listed 

threatened and endangered species and critical habitat included in the permit application, 

(2) any measures that the Services recommend (including monitoring and reporting) for 
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the protection of listed species, including any measures that would minimize any 

incidental take of listed species, and/or avoid likely jeopardy to a listed species or 

destruction or adverse modification of critical habitat, and/or (3) notify the State or Tribe 

that the Service(s) have no corrections to the list of species and critical habitat and/or that 

the Service(s) do not recommend any control measures. The Services’ 60 day review 

period does not constrain the Director’s ability to process the applicant’s permit 

application; however, the Director may not propose/publish the draft permit until the 60 

day review period has ended, unless the Director has received the Services’ response 

prior to that time. 

 In addition, the Services will receive, pursuant to existing regulations at 40 C.F.R. 

124.10(c)(1)(iii) and (e), all permit applications, as well as fact sheets or statements of 

basis (for EPA-issued permits), draft permits, and public notices for all permits. At this 

stage of the process, the Services will have the opportunity to review the draft permit and 

other materials and provide any additional input or suggested control measures to address 

effects to listed species or critical habitat. Together, the existing and new requirements 

related to transmittal of permitting documents to the Services will ensure that the 

Services have the opportunity to provide information and recommendations to the permit 

writer relating to any facility that may affect listed species. This information will be part 

of the public record for the permitting decision and the Director would be required to 

consider it as a relevant factor, along with all of the other relevant factors, in deciding 

what conditions to establish in the permit. Further, as explained in the MOA between 

EPA and the Services discussed elsewhere in today’s notice, EPA will use the full extent 
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of its CWA authority to object to a permit where EPA finds that issuance of NPDES 

permits under the NPDES rules. Nothing in this final rule would authorize the permit is 

likely to jeopardize the continued existence of a listed species or result in the destruction 

or adverse modification of designated critical habitat. The rule’s requirements insure a 

full vetting of information and concerns in the permitting process that must be considered 

by the Director. These requirements, coupled with the EPA’s commitment to exercise its 

oversight authority, insure that today’s rule is not likely to jeopardize the continued 

existence of a listed species or result in the destruction or adverse modification of 

designated critical habitat. 

 Among the recommendations that may be made by the Services to the facility and 

the Director are measures to minimize incidental take. EPA expects that any measures 

the Services recommend to minimize incidental take will be consistent with ESA 

regulations and guidances concerning reasonable and prudent measures. As stated in the 

ESA regulations under 50 CFR Part 402.14(i)(2), “Reasonable and prudent measures, 

along with the terms and conditions that implement them, cannot alter the basic design, 

location, scope, duration, or timing of the action and may involve only minor changes.” 

The Endangered Species Handbook (FWS and NMFS, 1998) explains that: “Measures 

are considered reasonable and prudent when they are consistent with the proposed 

action's basic design (e.g., narrowing of disturbed right-of-way at known species 

locations), location (e.g., temporary storage of equipment or other materials), scope, 

duration, and timing. Reasonable and prudent measures and terms and conditions should 

be developed in coordination with the action agency and applicant, if any, to ensure that 
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the measures are reasonable, that they cause only minor changes to the project, and that 

they are within the legal authority and jurisdiction of the agency or applicant to carry 

out.” 

 Installation of closed-cycle cooling is a major design alteration of a facility 

involving significant design and construction activities that are not in compliance with 

the ESA. (the range of costs associated with closed-cycle cooling is described elsewhere 

in today’s notice). Because installation of closed-cycle cooling does alter the basic 

design of a facility and would involve more than minor changes, as described in the 

Services’ regulations and Handbook, EPA does not expect that installation of closedcycle cooling would be specified as a measure solely for purposes of minimizing 

incidental take. The final rule at § 125.98(j) provides that nothing in this rule authorizes 

the take of threatened or endangered species of fish or wildlife. However, the Services 

may exempt take through an incidental take statement issued pursuant to ESA section 

7(o) or a permit under ESA section 10. See 16 U.S.C. 1536 (o) and 16 U.S.C. 1539. 

 Owners or operators This Clean Water Act rule cannot authorize take and 

does not purport to do so (nor can NPDES permits authorize take prohibited under the 

ESA). Accordingly, under § 125.98(b)(1), the permit writer, including EPA, must 

include, in the 316(b) permit requirements, standard language that states the permit does 

not authorize the take of existing facilities whose intakes are within the range of habitat 

of one or more federally Federally-listed threatened orand endangered species should . In 

addition, under § 125.96(g) (additional monitoring requirements) and § 125.97(g) 

(additional reporting requirements),where the Director requires additional measures to 
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protect listed species, monitoring and reporting requirements associated with those 

measures will be included in the permit. 

4. EPA Oversight of State-issued NPDES Permits to Protect Threatened and 

Endangered Species. 

 In 2001, the EPA, FWS, and NMFS signed a Memorandum of Agreement 

(MOA), (66 FR 11202, Feb. 22, 2001) with the objective of enhancing coordination 

between the agencies and to assist the agencies in executing their respective 

responsibilities under the Clean Water Act and Endangered Species Act. The MOA 

reflects, in part, the EPA’s longstanding commitment to overseeing the operation of state 

NPDES programs to ensure protection of endangered species with existing regulatory 

requirements. The EPA reaffirms its commitment to ensure coordination of the EPA’s 

and Services’ programs and appropriate protection of listed species, and EPA will follow 

the procedures in the MOA in overseeing implementation of this rule. 

 The MOA committed the EPA to a number of specific actions that are pertinent to 

today’s rule. Under the MOA, EPA committed, when contacted by the Services, to 

coordinate with the appropriate regional office of the USServices and the State/Tribe 

during the permit development process, in order to ensure that permits will comply with 

all applicable CWA requirements. One way in which coordination between EPA and the 

Services is facilitated is through the exchange of information about permits. The MOA 

facilitates such information exchange, as do EPA’s NPDES permit regulations at 40 

C.F.R. § 124.10, that preceded the MOA. These regulations require the Director to 

provide public notice and a comment period for draft permits, and to notify persons 
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identified at 40 C.F.R. § 124.10(c)(1)(iii) and (iv). Such persons specifically include 

Federal and State agencies with jurisdiction over fish, shellfish, and wildlife resource and 

over coastal zone management plans and thus include the U.S. Fish and Wildlife Service 

and the National Marine Fisheries Service (the Services) to determine what threatened or 

endangered species may be present. If owners or operators of existing facilities have a 

reasonable expectation that threatened or endangered species may be present, they must 

send select information in their NPDES permit application to the appropriate regional 

office of the Services. Permit applications submitted to the Director must include a 

certification that copies of only the source water baseline biological characterization 

section of the permit application have been sent to the Services. EPA also encourages 

Directors. 

EPA’s commitment to coordinate effectively with the Services on relevant public 

comments on draft permits concerning threatened and endangered species. includes 

following the procedures in section IX.A.6 and 7 of the MOA:

 Nothing in this final rule authorizes the take of federally listed threatened and 

endangered species. “Take” means an act which kills or otherwise harms listed species, 

including any modifications to federally designated critical habitat that significantly 

impact breeding, feeding, or sheltering. Nothing in this final rule, moreover, authorizes 

take for monitoring purposes except under the provisions of an incidental take statement 

or ESA section 10 permit. The Director may not exercise site-specific de minimis 
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authority to allow take. If threatened or endangered species may be present, the Director 

may not grant a de minimis exemption to the requirements of this final rule. 

 EPA has authority to object to State issued NPDES permits that it finds likely to 

have more than minor detrimental effect on federally-listed species or critical habitat as 

noted in section IX.A.6 of the 2001 “Memorandum of Agreement Between the 

Environmental Protection Agency, Fish and Wildlife Service and National Marine 

Fisheries Service Regarding Enhanced Coordination Under the Clean Water Act and 

Endangered Species Act” (66 FR 11202, Feb. 22, 2001), which reads: 

EPA may make a formal objection, where consistent with its CWA authority, or 

take other appropriate action, where EPA finds that a State or Tribal NPDES 

permit will likely have more than minor detrimental effect on Federally-listed 

species or critical habitat. 

For those NPDES permits with detrimental effects on Federally-listed species or 

critical habitat that are minor, it is the intention of the Services and EPA that the 

Services will work with the State or Tribe to reduce the detrimental effects 

stemming from the permit. For those NPDES permits that have detrimental effects 

on Federally-listed species or critical habitat that are more than minor, including 

circumstances where the discharge fails to ensure the protection and propagation 

of fish, shellfish and wildlife, and where the State or Tribe and the Services are 

unable to resolve the issues, it is the intention of the Services and EPA that EPA 

would work with the State or Tribe to remove or reduce the detrimental impacts 
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of the permit, including, in appropriate cases, by objecting to and Federalizing the 

permit where consistent with EPA's CWA authority. 

EPA will use the full extent of its CWA authority to object to a State or Tribal 

permit where EPA finds (taking into account all available information, including 

any analysis conducted by the Services) that a State or Tribal permit is likely to 

jeopardize the continued existence of any listed species or result in the destruction 

or adverse modification of critical habitat. 

EPA may review or waive review of draft State or Tribal NPDES permits (40 

CFR 123.24(d)). EPA will work with the Services through the local/regional 

coordinating teams to help determine which categories of permits should be 

reviewed for endangered species concerns. If EPA finds that a draft permit has a 

reasonable potential to have more than a minor detrimental effect on listed species 

or critical habitat, and review of a draft permit has been waived, EPA will 

withdraw this waiver during the public comment period (see 40 CFR 

123.24(e)(1)). 

 In addition,The grounds for EPA’s exercise of its discretionary authority 

to object to State or Tribal permits are described in accordance with the NPDES 

permitting regulations at 40 CFR 122.62(a)(2) concerningC.F.R. § 123.44. These 

include that the proposed permit modification based on availability of newfails to 

comply, or to ensure compliance with, any applicable requirement of this part, for 

example, that a permit application did not contain information, sufficient to 
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demonstrate that the permit will ensure compliance with applicable requirements. 

See 40 C.F.R. § 123.44(c)(1). 

If EPA considers a newly listed threatened or endangered species to constitute 

new information if the speciesobjects to a NPDES permit under the MOA, EPA 

will follow the permit objection procedures outlined in 40 CFR 123.44 and 

coordinate with the Services in seeking to have the State or Tribe revise its 

permit. A State or Tribe may be present near thenot issue a permit over an 

outstanding EPA objection. If EPA assumes permit issuing authority for a NPDES 

permit, EPA will consult with the Service prior to issuance of the permit (as a 

Federal action) as appropriate under section 7 of the ESA. 

 

While the MOA was adopted by the agencies in the context of NPDES permits for 

discharges of pollutants, it applies equally to NPDES permits that contain conditions for

cooling water intake structure. Thus, the Director may reopen a NPDES permit if a 

newly listed structures. Moreover, section 316(b) of the CWA accords EPA broad 

authority to protect waters of the United States from adverse environmental impacts 

associated with cooling water intake structures, including adverse effects to Federallylisted species and designated critical habitat. In implementing this provision, EPA is 

authorized to consider costs and benefits of different approaches to minimizing these 

impacts. The importance of listed species, and accordingly the benefits associated with 

preventing their extinction, animated Congress’s enactment of the Endangered Species 

Act in 1973. In the case of aquatic organisms that are listed as endangered or threatened, 
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and designated critical habitat, EPA has the authority, and will exercise the full extent of 

its authority, to object to a permit proposed by a State where EPA finds (taking into 

account all available information, and giving, as appropriate, substantial weight to the 

views of the Services) that a State or Tribal permit is likely to jeopardize the continued 

existence of such species or result in the destruction or adverse modification of such 

critical habitat. If the State permit is not modified to address EPA’s objections, EPA will 

issue the permit in consultation with the Services. EPA’s commitment to use the full 

extent of its CWA authority to object to permits that are likely to jeopardize listed species 

or result in the destruction or adverse modification of critical habitat is a safeguard for the 

protection of listed species and critical habitat. Additionally, where the Service 

communicates in writing to EPA its conclusion that a proposed State permit is likely to 

jeopardize the continued existence of a listed species, EPA will, upon request, provide the 

Service a written response. EPA’s commitment to use the full extent of its CWA 

authority, along with the other provisions of the rule requiring the EPA, the Services, and 

State Directors to fully consider effects to threatened orand endangered species may be 

present near a cooling water intake structureand critical habitat and include appropriate 

protections in NPDES permits, insures that the rule is not likely to jeopardize the 

continued existence of listed species or result in the destruction or adverse modification 

of designated critical habitat. 

 EPA notes that the existing NPDES regulations at 40 CFR 124.10 require the 

Director to provide public notice and a comment period for draft permits. This same 

paragraph also requires the Director to notify the persons identified at 40 CFR 
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124.10(c)(1)(iii) and (iv). These include Federal and State agencies with jurisdiction over 

fish, shellfish, and wildlife resource and over coastal zone management plans; this 

includes the U.S. Fish and Wildlife Service and the National Marine Fisheries Service. 

L. Permits for Existing Facilities Are Subject to Requirements under Other 

Federal Statutes 

EPA’s NPDES permitting regulations at § 122.49 list Federal laws that might 

apply to the issuance of NPDES permits under the NPDES rules. These include the Wild 

and Scenic Rivers Act, 16 U.S.C. 1273 et seq.; the National Historic Preservation Act of 

1966, 16 U.S.C. 470 et seq.; the Coastal Zone Management Act, 16 U.S.C. 1451 et seq.; 

and the National Environmental Policy Act, 42 U.S.C. 4321 et seq. For a brief description 

of each of these laws, see § 122.49. The provisions of the Magnuson-Stevens Fishery 

Conservation and Management Act, 16 U.S.C. 1801 et seq., relating to essential fish 

habitat might also be relevant. Nothing in this final rule would authorize activities that 

are not in compliance with these or other applicable Federal laws (e.g., Marine Mammal 

Protection Act,EPA’s permit application requirements ensure that FWS and NMFS will 

have—and other Federal agencies as well, should have—a broader information base from 

which to make informed decisions. Note also that, in the case of EPA-issued permits, 

EPA’s NPDES permitting regulations specifically require following the requirements of 

specific Federal laws that may apply to the issuance of NPDES permits. 16 U.S.C. 1361 

et seq., and Migratory Bird Treaty Act, 16 U.S.C. 703 et seq.).
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IX. Cost Development and Economic Impact Analysis 

This section summarizes EPA’s analysis of the social cost and economic impact 

for three regulatory options. BesidesIn addition to today’s rule, referred to as the Final 

Rule, EPA analyzed two other options similar to those options at proposal, which are 

referred to here (see section VI.D Other Options Considered for continuity as “Proposal 

Option x.”Today’s Final Regulation for more context). The regulatory options can be 

described as follows:-: 

 Final Rule: ImpingementFlexible impingement mortality performance 

standard for existing units based on modified traveling screens with fish 

returns for all facilities with flowDIF greater than 2 mgd, closed-cycle 

cooling or its equivalent for new units (except for repowered units that

are high energy efficiency units), for impingement and entrainment, and a 

national BTA standard that requires a site‐specific determination of 

entrainment BTA for all other existing units at existing facilities; 

 Proposal Option 2: Intake flow commensurate with closed-cycle cooling 

for facilities that have a design intake flow of greater than 125 mgd, 

flexible impingement mortality limitations based on modified traveling 

screens with fish returns for all facilities with flowDIF greater than 2 mgd, 

and closed-cycle cooling or its equivalent for new units; and 

 Proposal Option 4: ImpingementFlexible impingement mortality 

limitations based on modified traveling screens for all facilities with 
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flowDIF 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 offor impingement mortality controls forat facilities 

with flow less than or equal to 50 mgd. 

 The first part of this section provides an overall summary of the costs of the 

regulatory options to regulated facilities and Federal and State governments. This 

discussion is followed by a review of the method for developing compliance cost 

estimates. The third part provides an estimate of the total social costs of the regulatory 

options. The final part reviews the economic impact of the regulatory options. 

A. Overview of Costs to Regulated Facilities and Federal and State 

Governments 

ForIn estimating the total cost and economic impact of the regulatory options, 

EPA estimated costs for the following components: capital costs and other one-time 

costs; installation downtime costs; annual operation and maintenance costs; and 

recordkeeping, monitoring, entrainment-related studies, and reporting costs. All of these 

costs are included in the economic impact analysis for the final rule. The cost estimates 

reflect the incremental costs attributed only to this final rule. For example, facilities 

already having closed-cycle recirculating systems as defined at § 125.92 will meet the 

impingement mortality and entrainment standards of today’s rule and, therefore, 

wouldwill not incur costs to retrofit new technologies. These facilities, including those in 

New York and California, wouldwill still incur permitting costs. EPA has established that 
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existing closed-cycle coolingrecirculating systems maywill comply with the impingement 

BTA requirements. 

 For the economic analysesanalysis, EPA distinguished between the two industry 

groups regulated by the standards for existing facilities as follows: 

 Electric Power Producers (electric generators)—facilities owned by investorowned utilities, municipalities, States, Federal authorities, cooperatives, and 

nonutilities, whose primary business is electric power generation or related 

electric power services. 

 Manufacturing and Other Industries (manufacturers)—facilities in the paper, 

aluminum, steel, chemicals, petroleum, food and kindred products (primary 

manufacturing industries), and other industries. In addition to engaging in 

production activities, some of these facilities also generate electricity for their 

own use and occasionally produce excess power for sale.

For a more detailed discussion of costs to complyingregulated facilities and costs 

to Federal, State, and local governments, see Chapter 8 of the TDD and Chapter 3 of the 

EA. 

Electric generators incurring costs include facilities owned by private firms, 

governments, and electric cooperatives. Manufacturers incurring costs include facilities 

owned by private firms only. The administrative costs to Federal, State, and local 

governments include the costs of rule implementation—e.g., permits, monitoring, and 

working with facilities subject to the final rule to achieve compliance. 
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In the economic analysesanalysis, EPA accounted for these costs on an asincurred basis. They are usedreported on a pre-tax or after-tax basis, depending on the 

specific component of the analysis. These costs also underlie the analysis of the social 

costs of the regulatory options.

B. Development of Compliance Costs 

This section describes the data and methods used to estimate compliance costs of 

the options considered for today’s final rule. Costs were developed for technology 

controls to address impingement mortality separately from technology controls for 

entrainment because the requirements of the various rule options considered may lead to 

different technologies being used by each facility to comply. The options considered may 

impose different compliance timelines for impingement mortality and entrainment 

control technologies, although decision making has been synchronized to avoid 

investments in impingement BTA controls that could later be rendered obsolete by the 

BTA requirements for entrainment. Different methodologies were used and each is 

briefly described below. More detailed information on these methodologies and costs of 

other technologies and regulatory approaches are available in Chapter 8 of the TDD. 

1. Combined Facility-Specific and Model-Facility Approach 

 EPA estimated national level costs for regulated facilities under the final rule and 

other regulatory options. In general, facility-specific data can be used to determine the 

requirements that apply to a facility and whether that facility already meets the final 

rule’s requirements. This approach requires facility-specific technical data for the 

approximately 1,065 facilities that EPA estimates will be subject to the final rule. The 
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change in the number of facilities subject to the final rule compared to the number 

estimated at proposal is attributable to changes in how EPA accounted for baseline 

closures. See Appendix H of the EA for more details. An alternative approach is to 

develop a series of model facilities that exhibit the typical characteristics of the regulated 

facilities and calculate costs for each model facility; EPA would then determine how 

many of each model facility would be needed to accurately represent the full universe of 

regulated facilities. 

 The approach used in this effort involved calculating compliance technology costs 

for 338 individual facilities for which EPA had detailed technical data from its 

questionnaires regarding the intake design and technology. Specifically, these are the 

facilities that completed the detailed technical questionnaire. Where facilities reported 

data for separate cooling water intake structures, EPA derived compliance technology 

costs for each intake, and summed these intake costs to obtain total costs for each facility. 

EPA used the actual facility data to construct model facilities. Each model facility’s costs 

were then multiplied by a specific weighting factor, derived from a statistical analysis of 

the industry questionnaire, to obtain industry-wide costs. The weighting factors are 

similar to the ones derived during the development of the 2004 Phase II and 2006 Phase 

III rules. 

2. Updates to the Survey Data 

 For the 2004 Phase II rule analysis, EPA developed facility-specific cost estimates 

for all facilities and published those costs in an appendix (69 FR 41669, July 9, 2004). 

Since the initial implementation of the 2004 Phase II rule, EPA identified several 
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concerns with using only the facility-specific costing approach, and the use of those costs 

in Appendix A. Since 2004 EPA has collected data from industry and other groups as 

described in sectionSection III of the proposed rule (76 FR 22183, April 20, 2011). These 

data generally reflect changes to actual intake flow, design intake flow, intake velocity, 

technology in place, and operational status. EPA developed a new master database 

including this new data to supplement the data from the detailed technical questionnaire. 

Although it has been more than 10 years since the detailed technical questionnaire was 

initially collected, EPA has undertaken more than 50 site visits and reviewed available 

literature. In addition, EPA compared its data with that collected by Edison Electric 

Institute, Electric Power Research Institute, and the Energy Information Administration. 

On the basis of that review, EPA concluded that the master database is representative and 

reasonably reflects costs for all facilities.111 The following section describes how EPA 

used this new database to estimate compliance costs. 

3. Tools for Developing Compliance Costs 

 During development of the 2004 Phase II rule, EPA began developing a 

spreadsheet-based tool that would provide facilities and permit authorities with a simple 

and transparent method for calculating facility-specific compliance costs. EPA refined 

the tool in developing the Phase III regulations. EPA has since made further refinements 

to the cost tool, which was used to calculate the compliance costs for impingement 

 

111 EPA notes that, while it has not collected updated technical information for every facility, it has updated 

financial data, as discussed later in this section. 
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mortality for today’s final rule. The cost tool employs a decision tree (for a graphical 

presentation of the decision tree, see Chapter 8 of the TDD) to determine a compliance 

response for each model facility. The decision tree assigns a technology costing 

“module” for the retrofit to a given technology. Impingement cost estimates are derived 

through a series of computations that apply facility-specific data (such as DIF, width of 

intake screens, and such) to the selected technology module. Cost tool outputs include 

capital costs, incremental operation and maintenance costs, and installation downtime (in 

weeks). 

 To calculate the compliance costs of retrofitting to closed-cycle cooling for 

controlling entrainment, EPA used a second tool based on a cost-estimating spreadsheet 

using a modified version of a similar tool developed by the Electric Power Research 

Institute (EPRI). EPRI’s first draft methodology presented three levels of capital cost 

according to the relative difficulty of the retrofit project (easy, average, and difficult). For 

electric generators, EPA used costs for the average level of difficulty because it was 

developed across a broad spectrum of facilities and is the most appropriate for estimating 

national level costs rather than lower or upper bounds. For manufacturers, EPA used the 

difficult level of retrofit costs. This reflects the more complex water systems and 

technical challenges to retrofitting closed-cycle cooling at multiple locations within a 

manufacturing facility. In site visits, EPA found the largest manufacturing facilities had 

multiple intakes, distributed the water to multiple production processes, have already 

significantly increased water reuse as a result of water audits, and generally operate a 

complicated water distribution network at the entire facility, and would therefore require 
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multiple retrofits to convert the facility to be commensurate with closed-cycle 

recirculating system.112 Accordingly, EPA determined that the difficult level of retrofit 

costs is more representative for purposes of estimating national level costs. EPA’s tool 

includes additional modifications to EPRI’s methodology, such as increased compliance 

costs for approximately 25 percent of facilities to reflect the additional expense of noise 

control or plume113 abatement, and using only the cooling water flow rate for non-contact 

cooling water flow114 for purposes of estimating costs for closed-cycle cooling. EPA has 

included the spreadsheet tools in the docket for today’s final rule to assist both facilities 

and permit authorities in estimating compliance costs (see DCNs 10-665512-6650 and 

12-6651 for the cost tool, as well as and DCN 10-6930 for EPRI’s retrofit analysis). 

4. Which Technologies Form the Basis for Compliance Cost Estimates? 

 EPA identified two broad classes of control technologies that may be used 

singularly or in combination to comply with the final rule. These classes of control 

technologies are (1) technologies that address impingement mortality, and (2) 

technologies that address entrainment. For further details, see Section VI. 

 

112 A refinery, for example, may have dozens of heat exchange processes throughout the plantfacility, 

including a mix of wet and dry non-contact cooling equipment. 

113 The EPRI tool includes drift abatement technologies in its cost assumptions, so no additional costs were 

included for drift eliminators. 

114 As described in the TDD, EPA used only non-contact cooling water flows in determining the proper size 

for wet cooling towers. Cooling towers are not widely used for contact cooling or process water, so these 

flows were excluded. For electric generators, the vast majority of flow is non-contact cooling, but 

manufacturers are more varied in their water usage. 
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 For the impingement mortality requirements, EPA analyzed data from a wide 

variety of technologies and facilities, and concluded that modified (Ristroph (or 

equivalent) 3/8” mesh traveling screens with fish-friendly fish handling and returns are 

the most appropriate basis for determining compliance costs.115 As discussed in Section 

VI of this preamble, a facility may also comply with impingement mortality requirements 

by meeting a maximum intakelow velocity limitcompliance alternative, operating a 

closed-cycle recirculating system as defined at § 125.92,(c), or employing an existing 

offshore velocity cap as defined at § 125.92.(v). On the basis of facility-specific data, 

EPA made a preliminary assessment of which model facilities would not currently meet 

impingement mortality requirements through any of these pre-approved technologies, and 

assigned technology costs on the basis of modified traveling screens with a fish handling 

and return system if the existing intake used traveling screens. If the intake does not 

currently use traveling screens, EPA assigned costs for installing technologies that would 

comply with the low velocity standardcompliance alternative (larger intakes, wedgewire 

screens, or variable speed pumps) based on site-specific conditions. These assigned 

technologies will meet the BTA standard (see § 125.94(b)). Although EPA no longer 

requires installation of barrier nets or equivalent technologies to protect shellfish in all 

tidal waters, EPA included the cost of barrier net technology at approximately 10 percent 

 

115 Note that this does not preclude the use of other technologies; EPA simply used the available 

performance data in deriving the performance requirements. EPA’s research has shown that other 

technologies may also be capable of meeting the final rule requirements; however, these technologies are 

not available at all facilities. 
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of the intakes as a cost component for the “systems” approach to compliance with the IM 

performance standards. 

 EPA also analyzed the costs of those options associated with entrainment 

requirements based on wet cooling systems. In some cases, costs reflect installation of 

multiple technologies, as impingement mortality and entrainment control requirements 

were applied separately to each facility. EPA also evaluated other technologies for 

reducing entrainment, such as seasonal operation of cooling towers, partial towers, 

variable speed pumps, and fine-mesh screens. The costs of the final rule include but are 

not limited to permit applications; characterization of the source water, intake structures 

and any technologies in place; studies of impingement and entrainment; and 

recordkeeping, monitoring, and reporting. The costs also include costs of technologies for 

complying with the BTA for IM; the cost of additional technologies that may be required 

to meet the site-specific BTA for entrainment are not included, nor are costs for 

additional measures that may be required for protection of listed threatened and 

endangered species. Section VI further describes the performance of these technologies. 

A detailed discussion of how the costs were developed is in Chapter 8 of the TDD. 

5. How is Installation Downtime Assessed? 

 Installation downtime is the length of time that a facility might need to shut down 

for installing a compliance technology. Downtime estimates primarily assume that the 

facility would need to completely shut down operations for some portion of the 

installation period to retrofit an intake, such as relocating an intake, connecting wet 

cooling systems into the facility, or reinforcing condenser housings. EPA estimated 
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downtime as incremental outages, taking into account the periodic outages all facilities 

incur as part of preventative maintenance or routinely scheduled outages. For example, 

nuclear facilities have refueling outages approximately every 18 months lasting 

approximately 40 days.116 The entrainment control implementation periods under 

Proposal Option 2, 10 years for fossil fuel plantsfacilities and 15 years for nuclear 

plantsfacilities, would provide facilities with an opportunity to schedule the retrofit when 

other major upgrades are being done, thereby significantly reducing downtime. 

 For most facilities subject to impingement mortality, EPA assigned no 

incremental downtime. Facilities that are replacing or rehabilitating existing traveling 

screens typically do so one intake bay at a time without affecting the overall 

operations.117 EPA has also found that facilities that need to scrub screens do so during 

other routinely scheduled outages. For some compliance technologies, however, such as 

relocating an intake or expanding an existing intake to lower the intake velocity, several 

weeks of downtime may be incurred because these are more invasive tasks. See TDD 

Exhibit 8-4 for EPA’s net construction downtime for the various IM compliance 

technologies. 

 EPA reviewed historical retrofit data and site visits conducted since 2004 and has 

largely retained its assumptions for downtime from the Phase II and Phase III rules for 

facilities retrofitting to closed-cycle cooling. On average, EPA assumes the net 

 

116 Nuclear Energy Institute reported average length of outage from 2003 to 2009. 117 EPA’s data shows that facilities have an average of 4 to 5 bays. 
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installation downtime for retrofitting to closed-cycle cooling retrofit for non-nuclear 

electric generators is 4 weeks. This total downtime allows for the tie-in of the closedcycle system to the existing cooling water system. The refueling outage downtime, the 

safety-sensitive nature of nuclear facility retrofits, and other data in EPA’s record 

supports 28 weeks as the net construction downtime for nuclear facilities. EPA converted 

downtime for manufacturing facilities that use cooling water for power and steam 

generation into the incremental cost for purchasing electricity during the outage. For 

individual process units other than power generation units at a manufacturing facility, on 

average the downtime was assumed to be zero. In EPA’s extensive experience with 

manufacturers, EPA’s record reflects that 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. For further discussion of how EPA accounted for 

installation downtime in estimating national costs, see below. 

6. How is the Energy Penalty Assessed? 

 The term energy penalty in relation to a conversion to closed-cycle cooling has a 

number of different interpretations. The first is the extra power required to operate fans at 

a mechanical draft cooling tower and additional pumping requirements (sometimes 

referred to as auxiliary power consumptionenergy requirements or parasitic loads). The 

second is the lost power output because of the reduction in steam turbine efficiency from 

an increase in cooling water temperature relative to once-through cooling (often referred 

to as the turbine efficiency penalty or turbine backpressure penalty). EPA is clarifying 
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that it views the former as incremental O&M costs, and the latter is EPA’s interpretation 

of the energy penalty. Energy penalty costs apply only to facilities retrofitting to closedcycle cooling. without replacing the condenser. Facilities installing a new impingement 

mortality technology will not generally face an energy penalty and will generally see 

little or no measureable change in auxiliary power consumption. EPA’s national-level 

costs include both these costs. The auxiliary power consumption was included as a 

separate component in the operation and maintenance costs and was assessed for all 

facilities. The turbine efficiency penalty was typically expressed as a percentage of power 

output. EPA estimates the turbine efficiency energy penalty for nuclear and non-nuclear 

power generation would be 2.5 and 1.5 percent, respectively (see Chapter 8 of the TDD). 

For most manufacturers generating their own electricity, EPA assumed the same energy 

penalty for turbine efficiency loss as estimated for non-nuclear power facilities (i.e., 

1.5 percent). 

7. How Did EPA Assess Facility-Level Costs for the National and Regional 

Economic Impacts Analysis? 

 As part of the economic impact analysis, EPA assessed the impact of the final 

rule’s requirements on electric generators in the context of national and regional 

electricity markets. 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, particularly Clean Air Act regulations. 
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Because IPM requires facility-specific costs for each analyzed facility, yet 

compliance costs were developed as weighted sums of model facility costs, EPA 

developed a waymethod to distribute the aggregate costs to facilities that were not 

themselves model facilities. For these facilities, EPA converted facility-level costs 

developed for model facilities to a cost per mgd DIF and then averaged these values to 

derive cost equations using DIF as the independent variable. These cost equations 

provide average costs that can be applied to any facility by simply scaling to that 

facility’s DIF. For details on the IPM analysis, see the EA, Chapter 76. For details on 

facility cost development, see the TDD, Chapter 8. 

8. How Did EPA Assess Costs for New Units? 

Power generation and manufacturing units that are a new unit as defined at § 

125.92(u) must meet an entrainment reduction performance standard based on closedcycle cooling or an equivalent reduction in entrainment for the cooling water component 

of the intake flow based on the DIF. This section briefly describes the data and methods 

used to estimate compliance costs for new units at existing electric generators and 

manufacturers. Chapter 8 of the TDD has a complete description of the methodology. 

a. New Units at Existing Electric Generators 

Compliance costs for new units at existing electric generators are estimated using 

a similar methodology to that used for estimating compliance costs for existing facilities. 

As described in ChapterChapters 6 and 8 of the TDD, however, there are a number of 

differences in costs between a closed-cycle cooling retrofit at an existing facility 

compared to installing closed-cycle cooling at a new unit. In general, these differences 
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result in lower costs for the installation of a closed-cycle recirculating system at a new 

unit (as compared to a retrofit scenario), due to improved efficiency of the turbine, the 

elimination of construction downtime, greater ease of integrating the closed-cycle system 

into the design and construction of the new unit, offsetting costs of certain system and 

construction components, and greater overall system optimization. 

EPA could not determine precisely which facilities will construct new units. 

Instead, EPA used an approach to estimate what portion of the new capacity (i.e., 

additional megawatts capacity to be constructed each year) would be subject to the final 

rule. Using national projections of increased generating capacity,118 EPA categorized the 

new capacity into fourthree groups for 316(b) compliance purposes: 1) subject to the 

Phase I rule,119 2) potentially subject to today’s final rule, but projected to be excluded 

from the entrainment requirements because they meet the definition of high energy 

efficiency, 3) subject to today’s final rule, but projected to install a cooling system that 

complies with the rule regardless of the rule requirements,120 and 43) subject to today’s 

 

118 Capacity increases include considerations for fuel type and whether the capacity increase would be 

realized as additional capacity or as part of a repowering project. Capacity not subject to Phase I was 

apportioned into stand-alone and repowered categories.. See Chapter 8 of the TDD for details. 119 New capacity that is part of a new facility (as defined by the Phase I rule) is subject to separate 

requirements not addressed by today’s rule. Today’s requirements for new units, however, are based on the 

Phase I approach and also require flow reduction commensurate with a closed-cycle recirculating cooling 

system. 

120 Data in the record show a marked increase in the use of closed-cycle cooling in facilities constructed in 

recent years and for those projected to be constructed in the near future. These data indicate that in the 

1990s (prior to the Phase I rule), 83 percent of new cooling systems installed were closed-cycle cooling 

systems and that the current trend was approximately 97 percent. Based on thisthese data and the 

understanding that not all repowering projects will involve new cooling systems EPA assumed that 75% 

percent to 90% percent of new units will be designed with a closed-cycle recirculating cooling system 
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rule and projected to incur compliance costs. Exhibit IX-1 presents the annualestimated 

total new capacity ofand the estimated capacity for new stand-alone and repowered units. 

Exhibit IX-1. Annual capacity additions in newly constructed generating units and repowered units by cost 

category

Exhibit IX‐1

Fuel typeType

Total including phaseIncluding 

Phase I 

Existing facilities onlyFacility New 

Units Only

New 

capacityCapacit

y

Repower

ed 

existing

Total

StandaloneAlone

Repower

ed

Total

MW MW MW MW MW MW

Fossil Fuel 295 364 659 80 373 453

Combined Cycle 3,264 

2,065 5,32

9 147 

2898 3,044

Total 3,559 

2,430 5,98

9 227 

3,271 3,497

Costs for closed-cycle cooling are assigned to a portion of new stand-alone units, as 

shown the generating capacities in Exhibit IX-3 only. 

Exhibit IX-3. Annual and 24-year total capacity at existing facilities requiring costs for closed-cycle

Exhibit IX‐3

Fuel typeType

Annual onlyOnly 24-year total onlyTotal Only

StandaloneAloneRepowered Tota

l 

StandaloneAloneRepowere

d

Total 

MW MW MW MW MW MW

Fossil Fuel 8 

93 10

1 191

2240 243

1

Combined Cycle 15 0 15 353 0 353

 

regardless of the requirements of today’s rule. See DCN 12-XXX6672. As a result, this category of new 

capacity was not assigned any compliance costs. 

Deleted Cells

Deleted Cells

Deleted Cells

Deleted Cells

Deleted Cells

Deleted Cells

Deleted Cells

Deleted Cells

Deleted Cells

Deleted Cells

Deleted Cells

Deleted Cells

Deleted Cells

Deleted Cells

Deleted Cells

Deleted Cells
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Total 23 

93 11

6 544

2240 278

4

EPA then estimated the total costs for the fourththird group (i.e., those units that 

would incur compliance costs) to comply with requirements for new units. EPA used 

certain assumptions regarding cooling system design to modify cost equations used for 

estimating closed-cycle retrofit costs at existing units and then applied the cost equations 

to the portion of projected new unit generating capacities that would be subject to the 

new unitsunit provisions of today’s rule. These costs include capital121 and O&M costs, 

as well as a reduction in net generating capacity due to auxiliary power consumption to 

operate the closed-cycle recirculating system. Due to the complex nature of constructing 

a new unit, there is no increase in the length of the construction project as a result of 

employing a closed-cycle system; similarly, there is no downtime, as the unit has not yet 

begun operating. See Chapter 8 of the TDD for more information. 

b. New Units at Existing Manufacturers 

 

121 The record indicates that the total estimated capital cost for installing a closed-cycle recirculating system 

at a new unit to comply with today’s rule ranges from a negative value (as compared to the cost for 

installing a once-through system) to a positive value that could approach the cost of an existing facility 

retrofit. Said differently, if one assumes that the new unit would have constructed a new intake structure, 

EPA’s record shows that the capital costs for the new unit once-through system would be greater than if the 

new unit installs a closed-cycle recirculating system. (See DCN 10-6650.) Alternatively, if the new unit did 

not require modification of the existing cooling system infrastructure, then the capital costs for installing a 

closed-cycle recirculating system would be similar to an existing facility retrofit minus some tie-in costs 

since the condenser is being replaced. While EPA envisions that the actual costs will vary (i.e., some will 

be in the negative portion of the range and others will be in the positive), EPA is also unable to project 

what cooling water intake arrangements a new unit will use. Consequently, for all new units, EPA selected 

a capital cost equal to the midpoint between the tower only and the easy retrofit costs. As a result, EPA 

assumed that the capital costs for these units was $154 per gpm in 2009 dollars which converts to $30,800 

to $60,060 per MW capacity depending on fuel type. For a more detailed discussion, see TDD Chapter 8. 
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On the basis of site visits to manufacturing facilities, EPA has observed that 

manufacturers are increasingly taking advantage of water conservation and reuse 

measures as a means of cost-cutting. EPA also notes that manufacturers are subject to a 

wide variety of ELGs and that, in the course of complying with requirements for those 

ELGs, a facility may also reduce its intake flow. (See Chapter 4 of the TDD.) A new unit 

provides the opportunity to employ such measures to the fullest extent in designing the 

new unit. The availability of water conservation and reuse opportunities, coupled with 

operational flexibility at plantsfacilities with multiple industrial processes, leads EPA to 

conclude that facilities installing new units at existing manufacturers will comply with 

the new unitsunit provisions through achieving the 90 percent reduction required at § 

125.94(e)(2). Thus, EPA concluded that the new unit provisions would result in no 

additional compliance costs for achieving flow commensurate with closed-cycle cooling 

at new units.122

To the extent that manufacturers are not able to incorporate water reuse measures 

as a means of complying with the new unit provision, EPA’s estimate of new unit costs 

for manufacturers may be an underestimate. Manufacturers generally withdraw less water 

than electric generators (including manufacturers who generate their own electricity). 

Thus EPA has concluded that any underestimation would be insignificant. 

 

122 EPA also notes that some manufacturers may also be able to increase reuse to a degree where the facility 

no longer meets the applicability thresholds of today’s rule. 
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C. Social Costs 

EPA assessed the costs to society resulting from the final rule and other options 

considered in development of this rule. The findings presented in this section assume that 

facilities with impoundments will qualify as having closed-cycle recirculating systems in 

the baseline.123 As a result, EPA assigned no compliance technology costs to these 

facilities; however, these facilities remain subject to today’s rule and are assigned 

administrative costs. To the extent that some of these facilities do not qualify as having 

closed-cycle recirculating systems in the baseline, the costs reported in this section may 

be underestimates. The social cost of regulatory actions includes costs to electric 

generators and manufacturers to comply with the final rule, and costs to States and 

federalthe Federal government to administer the rule. These costs are the opportunity 

costs to society of employing scarce resources to prevent the environmental damage that 

would occur without today’s rule. EPA estimated total social costs for existing and new 

units at existing facilities. 

In estimating social costs, EPA assumed that the final rule and other options 

considered in development of this rule will not affect the aggregate quantity of electricity 

or other affected goods and services sold to consumers. Thus, the social cost of regulatory 

requirements includes no loss in consumer and producer surplus from reduced sales of 

electricity or other goods and services produced by regulated facilities. The Agency 

 

123 In other words, EPA assumed facilities indicating use of an impoundment in response to their technical 

survey have lawfully created such impoundments for the purposes of cooling water. 
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calculated the social cost of the final rule and the other options considered, using two 

discount rates: 3 percent and 7 percent. 

For existing facilities, EPA assumedassumes that all facilities subject to the final 

rule will begin bearing costs associated with today’s rule beginning as soon as 2014, and 

likely complete investments associated with today’s rule by 2030, depending on the 

technology-installation schedules for the final rule and other regulatory options 

considered.124 EPA performed the social cost analysis over a 51-year period to reflect (1) 

the last year in which individual facilities are expected to achieve compliance (2030) 

under the final rule or any of the options considered, (2) the life of the longest-lived 

compliance technology installed at any facility (30 years), and (3) a period of five years 

after the last year of compliance technology operation during which benefits continue to 

accrue. Under this framework, the last year for which EPA has calculated projected costs 

is 2059, with benefits continuing beyond 2059, though on a diminishing basis, through 

2064.125 

 

124 EPA conducted the cost and economic impact analyses on a calendar-year basis; for the economic 

impact. For these analyses, EPA treatedused calendar year 2013 as the promulgation year of today’s rule 

and 2014 as the first post-promulgation analysis year. This slight difference from the actual promulgation 

year of 2014 results from the fact that EPA completed its cost and economic impact analyses for the final 

rule and alternative options before EPA decided to delay promulgation from 2013 to 2014. Because the rule 

is being promulgated during the first half of 2014, EPA concluded that it would be reasonable to continue 

using 2013 as the assumed promulgation year for the regulatory analysis. EPA expects the differences in 

the estimated costs and benefits of the rule due to this slight imprecision to be minimal.

125 For this analysis, EPA assumed that the last year of technology installation for all complyingregulated

facilities under any of the regulatory options—i.e., 2030—is also the first year of steady-state compliance 

with regulatory requirements. 
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To estimate social costs for existing facilities, EPA developed a year-explicit 

schedule of compliance outlays over the 46-year period from 2014 to 2059 according to 

cost-incurrence assumptions (for details on cost-incurrence assumptions, see EA, Chapter 

3). EPA then adjusted these costs for predicted real change (i.e., adjusted for inflation) to 

the year of their incurrence and discounted all costs to the beginning of 2013, the final 

rule’s promulgation year. used for the analysis. Because the analysis period extends 

beyond the useful life of some compliance equipment, the social cost analysis accounts 

for re-installation of impingement mortality compliance technologies after the end of 

their initial useful life periods. However, for the regulatory option that requires a specific 

entrainment control technology (e.g., wet cooling systems)—Proposal Option 2—EPA 

does not expect regulated facilities to completely rebuild these systems (components such 

as piping and the concrete basin can be reused). EPA accounted for other technology 

replacement costs (such as pumps and fill material) as part of ongoing operations and 

maintenance expenses. 

For new units at existing electric generators, EPA calculated an average annual 

amount of new capacity to be constructed during the 46-year social cost analysis period, 

beginning in 2014 and using EIA projections of electricity demand growth, and based 

new unit costs on that average.. While EPA does not expect the annual construction of 

new units to be constant, predicting the year-to-year fluctuations would be resource 

intensive. On average, EPA assumes that its estimate of new unit costs is reasonable. 

EPA accounted for compliance costs for these units on an as-incurred basis, as done for 

existing facilities. Similar to compliance costs for facilities subject to the final rule, EPA 
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analyzed costs incurred by State and Federal governments for administering the 

regulation on a year-explicit basis over the 46-year social cost analysis period. 

Exhibit IX-4 presents social costs for existing units at existing facilities under the 

final rule and other options considered, calculated using 3 percent and 7 percent discount 

rates. At the 3 percent discount rate, EPA estimates total annualized social costs of 

$283.3272 million for the existing unit provision of today’s rule, $261.7252 million for 

Proposal Option 4, and $3,999.7643 million for Proposal Option 2. At the 7 percent 

discount rate, these costs are $296.9295 million for today’s rule, $272.8 million for 

Proposal Option 4, and $3,893.0583 million for Proposal Option 2.126 See the EA 

(Chapter 7) for an explanation of why the annualized costs at the 3 percent discount rate 

are lower than the annualized costs at the 7 percent discount rate for the final rule and 

Proposal Option 4, while the inverse is the case for Proposal Option 2 (annualized costs 

at the 3 percent discount rate are higher than at the 7 percent discount rate). The largest 

component of social cost is the cost of regulatory compliance incurred by regulated 

 

126 Because EPA was unable to identify those facilities for which entrainment control technology would be 

established as BTA standards on a site-specific basis, the Agency did not analyze technology costs 

associated with these site-specific requirements. Consequently, the cost and economic analyses conducted 

in support of today’s rule assume that under the existing unit provision of the final rule and Proposal 

Option 4, Electric Generators and Manufacturers install IM technology only. These analyses also assume 

that under Proposal Option 2, Electric Generators with DIF exceeding 125 mgd install only cooling towers 

and all other Electric Generators install only IM technologies. Under Proposal Option 2, a small number of 

Manufacturers are assigned both IM and entrainment control technologies because of engineering issues 

associated with maintaining separation of contact and non-contact cooling water in some manufacturing 

operations. Although EPA did not estimate technology costs for facilities for which entrainment technology 

is established as BTA on a site-specific basis, EPA did include the costs for data collection and studies that 

facilities will need to perform in order to provide information to Directors to make these site-specific 

determinations. EPA included these costs in the administrative costs that are estimated for the final rule and 

other options considered. 
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facilities (as opposed to administrative costs estimated for States and federalthe Federal

government). These costs include (1) one-time technology and other initial costs of 

complying with the rule, (2) one-time costs of installation downtime, (3) annual fixed and 

variable operating and maintenance costs, including auxiliary energy requirement, (4) 

value of energy penalty from operation of compliance technology, and (5) permitting 

costs (initial and follow-up start-up costs, initial permit costs, annually recurring costs 

associated with monitoring, and non-annually recurring permitting costs). 

As shown in Exhibit IX-4, complianceCompliance costs estimated for electric 

generators account for the largerlargest share of total compliance-related social cost and 

direct compliance cost under all three options. On a per-facility basis and at the 3 percent 

discount rate, the annualized pre-tax compliance costs for the electric generators segment 

under today’s final rule are $0.4 million, $0.4 million under Proposal Option 4, and $6.9

million under Proposal Option 2.127 For manufacturers, the average cost per regulated 

facility at the 3 percent discount rate is $0.1 million under the final rule and Proposal 

Option 4, and $0.54 million under Proposal Option 2.128 As shown in Exhibit IX-4,

EPA’s analysis found a similar profile of per facility costs using the 7 percent discount 

rate (see EA Chapter 87 for additional detail). EPA’s estimate of Federal and State 

 

127 Calculated usingby dividing direct compliance costs for each type of facility by the total of 544 electric 

generators covered bysubject to today’s rule on the basis of facility count-based weights (see EA Appendix 

H). 

128 Calculated using the total of 521 manufacturers covered bysubject to today’s rule on the basis of 

technical weights (see EA Appendix H). 
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government costs for administering this rule is small in relation to the estimated direct 

cost of regulatory compliance. EPA estimates $1.0 million in annual administrative costs 

to States and Federal government for the final rule, using both the 3 and 7 percent, . 

discount rates. These cost values are the same for Proposal Option 4. EPA estimates $0.7 

million in annual administrative costs to States and the Federal government for Proposal 

Option 2, regardless of the discount rate used. 

Exhibit IX-4. Total annualized social costs –existing units at existing facilities (in millions, 2011 dollars)a

 Proposal Option 4 Final Rule Proposal Option 2 

Using 3 percent discount rate 

Direct Compliance Costs 

Electric Generators $208.7202.9 $209.6203.7 $3,755.6413.3

Manufacturers $52.047.8 $7267.7 $243.4229.2

Total Direct Compliance Cost $260250.7 $282.3271.4 $3,999.0642.5

State and Federal Administrative Costs $1.0 $1.0 $0.7 

Total Social Costs $261.7251.8 $283.3272.4 $3,999.7643.2

Using 7 percent discount rate 

Direct Compliance Cost: 

Electric Generators $216.4219.2 $217.3220.0 $3,638.9339.3

Manufacturers $55.451.9 $78.674.2 $253.4243.0

Total Direct Compliance Cost $271.81 $295.9294.3 $3,892582.3 

State and Federal Administrative Costs $1.0 $1.0 $0.7 

Total Social Costs $272.81 $296.9295.3 $3,893583.0 

a Cost estimates exclude costs associated with baseline closure facilities. 

EPA also estimated the cost for installing closed-cycle cooling system 

technologyrecirculating systems at new units at existing electric generators, to reflect the 

costs of today’s rule. As shown in Exhibit IX-5, EPA estimated that the new unitsunit

provision of the final rule will result in an annualized cost of $14.12.5 million and $122.0 
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million using 3 percent and 7 percent discount rates, respectively, including compliance 

costs to facilities and administrative costs to States and federalFederal government. 

The Agency estimated that at a 3 percent discount rate, the total social cost of the 

final rule, including the existing and new unitsunit provisions, will be $297.4275 million. 

At a 7 percent discount rate, this cost is $308.9297 million. 

Exhibit IX-5. Annualized total social cost of the final rule – existing and new units at existing facilities (in 

millions, 2011 dollars)a,b

 3% Discount Rate 7% Discount Rate 

New Units $14.12.5 $122.0 

Existing Units $283.3272.4 $296.9295.3

Existing and New Units $297.4274.9 $308.9297.3

a Cost estimates exclude costs associated with baseline closure facilities. 

b

 Values may not add due to rounding. 

D. Economic ImpactImpacts

EPA used several analytic approaches to assess the economic impact of today’s 

rule and the other options considered, on electric generators and manufacturers. EPA 

conducted separate analyses for electric generators and manufacturers. Though 

undertaken with differences in methodology, the analyses for both regulated facility 

segments involve (1) a cost-to-revenue analysis, and (2) a business value test based on an 

after-tax cash flow analysis. using different methodologies for each regulated facilities 

segment. The following sections summarize the methodologies EPA used to conduct the 

economic impact analyses and the findings of these analyses. EPA conducted the 

economic impact analyses discussed in this section for existing facilities; the Agency 
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used compliance cost estimates from the EPA engineering analysis (see sectionTDD 

Section X.B). 

1. Electric Generators 

For the electric generators segment, EPA assessed the economic impact of the 

existing unit provision of the final rule and other options it considered in three ways: (1) 

the financial burden associated with a particular regulatory option on facilities and 

entities that own them, (2) how potential changes in the price of electricity would affect 

electricity consumers, in general, and residential households, in particular, and (3) 

broader economic impacts on the electricity market, taking into account the 

interconnectedness of regional and national electricity markets. In preparing the first two 

sets of analyses, EPA developed and used sample weights to extrapolate impacts assessed 

initially at the level of a sample of facilities, to the full population of facilities subject to 

the final rule. For information on how EPA developed and used sample weights, see the 

EA, Appendix H. 

In addition, EPA assessed the impact of the new unit provision of the final rule on 

decisions of existing facilities to construct stand-alone new units that would be subject to 

the new unit provision. EPA made this assessment in two ways: (1) on the basis of 

comparison, on a per MW basis, of compliance costs for new units to the overall cost of 

building and operating generating units and (2) as is the case with the existing unit 

provision, in the context of regional and national electricity markets, taking into account 

their interconnectedness. 
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a. Cost-to-Revenue Analysis for Regulated Facilities and Their Parent Entities – 

Existing Unit Provision of the Final Rule 

EPA assessed the cost to regulated facilities and their parent entities on the basis 

of a cost-to-revenue analysis. For each analysis level (facility and parent entity), the 

Agency assumed, for analytic convenience and as a worst-case scenario, that none of the 

compliance costs would be passed on to consumers through electricity rate increases and, 

instead, would be absorbed by regulated facilities and their parent entities.129 EPA 

developed this analysis for 544 electric generators.130

ai. Cost-to-Revenue Analysis for Regulated Facilities 

To provide insight into the potential significance of the compliance costs to 

regulated facilities, EPA calculated the ratio of annualized after-tax compliance costs to 

baseline annual facility-level revenues. In the cost-to-revenue comparisons, EPA used 

cost-to-revenue thresholds of 1 and 3 percent to categorize facilities according the 

potential economic impact of the rule. EPA assessesconcludes that facilities incurring 

costs below 1 percent of revenue will not face significant economic impacts, while 

 

129 As discussed in EA Chapter 2A: Industry Profiles, the majority of regulated electric generators operate 

in States with regulated electricity markets. EPA estimates that facilities located in these States may be able 

to recover compliance cost-based increases in their production costs through increased electricity prices. 

This depends on the business operation model of the facility owner(s), the ownership and operating 

structure of the facility itself, and the role of market mechanisms used to sell electricity. In contrast, in 

States where electric power generation has been deregulated, cost recovery is less certain. While facilities 

operating within deregulated electricity markets may be able to recover some of their additional production 

costs through increased revenue, EPA cannot determine the extent of cost recovery ability for each facility. 

130 EPA calculated this number as a weighted estimate using facility count-based weights. This number 

excludes facilities estimatedassumed either to have already retired their steam operations or expected to do 

so in the future. 
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facilities with costs of at least 1 percent but less than 3 percent of revenue have a chance 

of facing economic impacts, withand facilities incurring costs of at least 3 percent of 

revenue have a higher probability of significant economic impacts. For a more detailed 

discussion of the methodology EPA used for the facility-level cost-to-revenue analysis, 

see EA Chapter 4. 

Exhibit IX-6 presents a summary of the facility-level cost-to-revenue analysis 

results for the final rule and other options considered. EPA estimates that overall, under 

the final rule, 8486 percent of regulated facilities will incur compliance costs of less than 

1 percent of revenue. Under Proposal Option 4, 8587 percent of regulated facilities would 

also incur costs of less than 1 percent of revenue. EPA estimates that Proposal Option 2 

would result in 6242 percent of facilities incurring costs exceeding 1 percent of revenue, 

and 4843 percent incurring costs exceeding 3 percent of revenue. 

Exhibit IX-6. Facility-level cost-to-revenue analysis results for the final rule and options considereda

Option 

Number of facilities with cost-to-revenue ratio 

< 1% ≥ 1% and < 3% ≥ 3% 

# % # % # % 

Proposal Option 4 46147

5

84.787.

4% 4435 8.16.5% 3731 6.85.7% 

Final Rule 45647

0

83.886.

5% 4840 8.87.4% 3731 6.85.7% 

Proposal Option 2 20522

8

37.741.

9% 7779 14.25% 260235

47.843.

2% 

a Facility counts exclude baseline closures. 

b EIA reports no revenue for 1 facility (2 on a weighted basis). Therefore, EPA 

conducted this analysis for 321339 facilities (542 on a weighted basis). For 

more information on facility sample weights see EA Appendix H.
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bii. Cost-to-Revenue Analysis for Regulated Parent Entities 

EPA also assessed the economic impact using the cost-to-revenue metric at the 

level of the parent entity. This analysis, which focuses on domestic parent entities with 

the largest ownership share in the facility, provides insight on the impact of compliance 

requirements on those entities that own more than one regulated facility. The analysis 

helps to answer the question of whether owning multiple facilities that needare required

to comply with today’s rule causes financial stress at the entity level. For each identified 

parent entity, EPA aggregated facility-level, annualized, after-tax compliance costs to the 

level of the parent entity and compared these entity-level costs to entity-level revenue. 

Similarly to the facility-level analysis, EPA used cost-to-revenue thresholds of 1 

and 3 percent to categorize facilities according the potential economic impact of the rule. 

EPA used two weighting approaches for this analysis: (1) using facility-level weights, but 

without entity-level weights and (2) using entity-level weights, but without facility-level 

weights. These approaches, which are described in Appendix H of the EA, provide a 

range of estimates for the number of entities incurring compliance costs and the costs 

incurred by any entity that owns a regulated facility. (For a more detailed discussion of 

the methodology used for the entity-level cost-to-revenue analysis, see EA Chapter 4). 

Exhibit IX-7 presents results for the entity-level analysis for the two weighting 

schemesapproaches. EPA estimates that between 116123 and 159 entities own regulated 

facilities. Further, the Agency estimates that the majoritybetween 91 and 94 percent of 

parent entities will incur annualized costs of less than 1 percent of revenues under the 

final rule (between 91 and 94 percent).. This finding also holds under the two other 
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options EPA considered, with between 91 and 94 percent of entities incurring costs of 

less than 1 percent of revenue under Proposal Option 4 and between 6570 and 7578

percent under Proposal Option 2. 

Exhibit IX-7. Entity-level cost-to-revenue analysis resultsresultsb

Parent entity type Total number 

of entities 

Number of entities with cost-to-revenue ratio of 

< 1% ≥ 1% and < 3% ≥ 3% Unknowna

# % # % # % # % 

Using Facility-Level Weights 

Proposal Option 4 116123 105112 90.591.1% 3 2.64% 10 0.90% 78 6.05%

Final Rule 116123 105112 90.591.1% 3 2.64% 10 0.90% 78 6.05%

Proposal Option 2 116123 7586

64.769.9

% 1817

15.513.8

% 1612 139.8% 78 6.05%

Using Entity-Level Weights 

Proposal Option 4 159 149150 93.794.2

% 

20 1.30.0% 0 0.0% 89 5.08%

Final Rule 159 149150 93.794.2

% 

20 1.30.0% 0 0.0% 89 5.08%

Proposal Option 2 159 119124 74.878.1% 2218 13.811.6

%

97 5.74.4

%

89 5.08%

a

 EPA was unable to determine revenues for 78 parent entities (89 weighted).

b

 This analysis assumes no cost pass-through to electricity consumers.

2b. Potential Electricity Price Effects – Existing Unit Provision of the Final Rule

As an additional measure of economic impact, EPA conducted two assessments of 

the potential price effects on electricity of today’s rule: (1) the annual increase in 

electricity costs per MWh (megawatt hour) of total electricity sales and (2) the potential 

annual increase in household electricity costs. For analytic convenience and as a worstcase scenario, the first analysis assumesthese assessments assume that all compliance 

costs will be passed through on a pre-tax basis to consumers as increased electricity 

prices. This full cost pass-through assumption represents a “worst-case” impact scenario 
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from the perspective of electricity consumers. Facilities that are merchant providers can 

only pass along costs only to the degree that they are competitive with other generators in 

the dispatch process.131 This assumption is the opposite of EPA’s assumption in the 

facility- and entity-level analyses discussed above—that facilities will pass none of the 

compliance costs through to consumers in electricity rate increases. If facilities are able to 

pass through all costs, the impacts in the previous subsection would not occur. The two 

conditions (no cost pass-through and full cost pass-through) could not occur at the same 

time. Thus, the results of the electricity price-effects analyses discussed in this section, 

and of the facility- and entity-level analyses discussed in Section IX.D.ba.1, should not 

be combined. EPA conducted this analysis for 544 electric generators. 

ai. Compliance Cost per Unit of Electricity Sales 

EPA assessed the potential increase in electricity rates by NERC region based on 

the annual cost of the regulatory options per unit of electricity sold. The Agency used two 

data inputs: (1) total pre-tax compliance cost by NERC region, and (2) estimated total 

electricity sales in the year 2020, to gauge the full effects of the rule. To calculate the 

total estimated annual cost in each NERC region, the Agency summed sample-weighted, 

pre-tax annualized compliance costs over regulated facilities by region. EPA then 

calculated the approximate average price impact per unit of electricity consumption by 

 

131 As discussed earlier in Section X.D.b.1, even though individual regulated facilities may not be able to 

recover all of their compliance costs through increased revenues, the market-level effect may still be that 

consumers will see higher overall electricity prices because of changes in the cost structure of electricity 

supply and resulting changes in market-clearing prices in deregulated electricity markets. 
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dividing total compliance costs by the reported total MWh of sales in each NERC region. 

(Details of this analysis are presented in the EA, Chapter 4.) 

As reported in Exhibit IX-8, under the existing unitsunit provision of the final 

rule, annualized compliance costs (in cents per kWh sales) range from nearly zero ¢$0.00

in the WECC region to $0.041 ¢040 in the HICC region. EPA reached the same 

findingfindings for Proposal Option 4. Under Proposal Option 2, costs range from nearly 

zero ¢$0.00 in the WECC region to $0.349 ¢351 in the HICC region. On average, across 

the United States, the final rule and Proposal Option 4 result in a cost of $0.011¢009 per 

kWh, while Proposal Option 2 results in a higher cost of $0.172¢155 per kWh. 
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Exhibit IX-8. Compliance cost per unit of electricity sales in 2020 by regulatory option and NERC region 

(2011 ¢/ KWh sales)a b 

NERC Regionc,d Proposal Option 4 Final Rule Proposal Option 2 

ASCC 0.000 0.000 0.000 

FRCC 0.015014 0.015014 0.176171

HICC 0.041040 0.041040 0.349351

MRO 0.013010 0.013010 0.194174

NPCC 0.008 0.008 0.126 

RFC 0.013011 0.013011 0.208200

SERC 0.014013 0.014013 0.225219

SPP 0.018009 0.018009 0.202078

TRE 0.014008 0.014008 0.269206

WECC 0.000 0.000 0.000 

United States 0.011009 0.011009 0.172155

a

 This analysis assumes full pass-through of all compliance costs to electricity consumers. 

b Cost values exclude baseline closures. 

c

 ASCC – Alaska Systems Coordinating Council; FRCC – Florida Reliability Coordinating Council; HICC – Hawaii 

Coordinating Council; MRO – Midwest Reliability Organization; NPCC – Northeast Power Coordinating Council; RFC – 

ReliabilityFirst Corporation; SERC – Southeastern Electric Reliability Council; SPP – Southwest Power Pool; TRE - Texas 

Reliability Entity, and WECC – Western Energy Coordinating Council. 

d No explicitly analyzed facilities are in the ASCC region. For more information on explicitly and implicitly analyzed regulated 

facilities, see EA Appendix H. 

bii. Cost to Households 

As an additional measure of the potential electricity price effects associated with 

the final rule, EPA estimated the potential annual increase in electricity costs per 

household and by NERC region. EPA used total annualized pre-tax compliance cost per 

MWh of sales, as estimated for the electricity rate impact analysis discussed above and 

the quantity of residential electricity sales per household as reported in the 2011 EIA 

database. To calculate the potential annual cost impact per household, EPA multiplied the 
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average cost per kWh by the average kWh per household estimated for each NERC 

region. (Chapter 4 of the EA presents details of this analysis.) 

As presented in Exhibit IX-9, under the existing unitsunit provision of the final 

rule, the average annual cost per residential household varies across NERC regions, 

ranging from $0.01 in WECC to $2.8582 in HICC. EPA reached the same 

findingfindings for Proposal Option 4. Under Proposal Option 2, the average annual cost 

per residential household also varies across NERC regions, ranging from $0.01 in WECC 

to $39.9731.72 in TRESERC. EPA estimated that on average, for a typical U.S. 

household, the final rule will resultsresult in aan annual cost of $1.2403 in higher 

electricity rates per household. EPA estimates that this cost would be $1.2403 per 

household under Proposal Option 4 and $19.1117.23 per household under Proposal 

Option 2. 
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Exhibit IX-9. Average annual cost burden per residential household in 2020 for the final rule and options 

considered, and by NERC region (2011 dollars)a b 

NERC regionc,d Proposal Option 4 Final Rule Proposal Option 2 

ASCC $0.00 $0.00 $0.00 

FRCC $1.9791 $1.9791 $23.8515 

HICC $2.8582 $2.8582 $24.4561 

MRO $1.350.99 $1.3802 $20.2618.10 

NPCC $0.6261 $0.62 $9.5352 

RFC $1.3210 $1.3210 $21.5020.64 

SERC $2.091.96 $2.091.96 $32.9731.72 

SPP $2.511.30 $2.511.30 $27.5810.71 

TRE $2.021.15 $2.021.15 $39.9730.59 

WECC $0.01 $0.01 $0.01 

United States $1.2403 $1.2403 $19.1117.23 

a

 The rate impact analysis assumes full pass-through of all compliance costs to electricity consumers. 

b. Cost estimates exclude baseline closures. 

c

 ASCC – Alaska Systems Coordinating Council; FRCC – Florida Reliability Coordinating Council; HICC – Hawaii 

Coordinating Council; MRO – Midwest Reliability Organization; NPCC – Northeast Power Coordinating Council; 

RFC – ReliabilityFirst Corporation; SERC – Southeastern Electric Reliability Council; SPP – Southwest Power Pool; 

TRE - Texas Reliability Entity, and WECC – Western Energy Coordinating Council. 

d

 No explicitly analyzed facilities are in the ASCC region. For more information on explicitly and implicitly analyzed 

regulated facilities, see EA Appendix H. 

As noted above, this analysis assumes that facilities will pass through to 

consumers all compliance costs through increased electricity rates. However, facilities 

and owningowner entities might not be able to recover all these costs through rate 

increases, thereby reducing the impact of today’s rule on electricity consumers. At the 

same time, EPA recognizes that electric generators that operate as regulated public 

utilities will generally recover environmental compliance costs through rate increases to 

consumers. 

cc. Barrier-to-Development Analysis – New Unit Provision of the Final Rule 
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EPA assessed the impact of the new unit provision of the final rule on decisions 

of existing facilities to construct stand-alone new units that would be subject to the new 

unit provision. As discussed earlier in this preamble, under this provision, electric power 

generating units that meet the definition of a new unit will be required to achieve intake 

flow commensurate with closed-cycle cooling. The question of potential impact of this 

provision on the construction of new stand-alone units is important because new standalone units will generally operate with higher energy efficiency and lower environmental 

impact than older electric generating capacity, which the new units would tend to 

displace as a source of electric power generation. As such, EPA sought to ensure that the 

new unit provision would not impede construction of stand-alone new units. 

For this analysis, EPA compared the compliance costs for new units to the overall 

cost of building and operating generating units, on a per MW basis. The purpose of this 

analysis is to determine 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 

stand-alone unit, and adversely affect the decision to construct the new stand-alone unit. 

This analysis showed that given the low cost of CCRS in relation to the cost of new 

capacity, the CCRS requirement will not pose a barrier to development of new standalone units. 

EPA also assessed the costs associated with the new unit provision of the final 

rule as part of its electricity market analysis, as discussed in the following section 

(Section IX.D). This analysis tests the impact of the new unit requirements on electricity 

markets accounting for the expected number and timing of new unit installations, and 
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provides additional insight on whether the costs of complying with the new unit provision 

of the final rule would affect future capacity additions. This analysis found no material 

effect of the final rule’s new unit provision on the number and type of new units that 

would be constructed. This finding also supports EPA’s conclusion that the new unit 

provision will not be a barrier to development of new capacity. 

d. Impacts in the Context of Electricity Markets – Existing and New Unit Provisions 

of the Final Rule

In analyzing the 2011the analyses for the previous 316(b) regulations, including 

the proposed existing facilities rule (proposed rule),rule, EPA used the Integrated 

Planning Model (IPM®),132 a comprehensive electricity market optimization model that 

assumes perfectly competitive wholesale electricity markets, to assess the proposed rule’s 

impactseconomic impact of regulatory options within the context of regional and national 

electricity markets.133 To assess facility and market-level effects of the final rule, EPA 

used an updated version of this same analytic system, the Integrated Planning Model 

Version 4.10 MATS (IPM V4.10_MATS) platform. 

Use of a comprehensive, market analysis system is important in assessing the 

potential impact of the final rule because of the interdependence of electricity generating 

 

132 Developed by ICF, Inc. 133 The IPM analysis, involves cash flow and present value concepts that are similar to the after-tax cash 

flow/business value analysis that EPA conducted for Manufacturers. 
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units in supplying power to the electric transmission grid. Increases in electricity 

production costs and potential reductions in electricity output at affectedregulated

facilities – whether due to the temporary shutdown of existing electric generating units 

during technology installation and/or the energy production penalties that can result from 

closed-cycle cooling – can have a range of broader market impacts that extend beyond 

the effect on regulated facilities and their direct customers. In addition, the impact of 

compliance requirements on directly affectedregulated facilities may be seen differently 

when the analysis considers the impact on those facilities in the context of the broader 

electricity market instead of looking at the impact on a stand-alone, single-facility basis. 

For the analysis of the proposed rule, EPA used the IPM version 3.02 EISA 

platform (IPM V3.02). Since then, the EPA Office of Air and Radiation and ICF have 

updated the IPM platform in several ways; these include accounting for recently passed 

Clean Air Act regulations and changes in the universe of electricity power facilities and 

units. These updates are incorporated in the IPM version 4.10 MATS platform. 

In addition, since publication of the proposed rule, EPA conducted IPM analysis 

using the IPM V4.10 platform (summer 2011), which is a more current platform 

compared to the IPM V3.02 EISA platform used for the proposed rule and includes the 

Proposed Transport Rule and the Proposed Toxics Rule. Although EPA performed more 

recent analyses using the IPM V4.10 platform, the regulatory options considered in this 

analysis do not correspond as well to those of today’s rule as the analysis of Market 

Model Analysis Option 1 (Proposal Option 1) that EPA performed for the proposed rule. 
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As a result, EPA concluded that it could not rely alone on the findings from the IPM 

V4.10 platform analyses for determinations for the final rule. 

Both the findings from the IPM analysis undertaken for proposal and the more 

recent IPM V4.10 platform analysis suggest very modest impacts from regulatory 

requirements that are similar to those of today’s rule. 

Given the findings of low impact from the IPM analysis performed at proposal 

and the similar findings from the summer 2011 analysis using IPM V4.10 platform, EPA 

assessed whether another IPM analysis, using the IPM V4.10 MATS platform, i.e., the 

most current IPM platform at the time of analysis, was warranted to evaluate the impacts 

of the final rule in the context of regional and national electricity markets or results for 

Proposal Option 1 were sufficient to evaluate these impacts. In this assessment, EPA 

accounted for the time and resources required to conduct an IPM run. Key considerations 

in this assessment are as follows: 

 First, EPA reviewed the impacts of Proposal Option 1 as estimated in the previous 

IPM analysis done using the IPM V3.02 EISA platform. This analysis found that 

Proposal Option 1 would have very little effect on the overall electricity market, 

in general, and the group of regulated facilities, in particular, at the national level 

and the NERC-region level. 

 Second, given the finding of very limited impact of the proposed rule, EPA then 

asked whether new analyses for the final rule using the updated IPM V4.10 

MATS platform would be expected to show materially different – specifically, 

higher – impacts than estimated for the proposed rule. EPA assessed that impacts 
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could differ for primarily two reasons – (1) differences in the requirements and 

cost of the final rule compared to Proposal Option 1 and (2) differences in the 

IPM analytic platform – and focused its question on these considerations. EPA 

first compared the costs and operational impacts of the final rule with those of 

Proposal Option 1. This comparison found that the final rule’s costs and impacts 

are likely to be substantially lower than those estimated for the proposed rule. 

Second, EPA considered whether the changes in the IPM platform would affect 

materially the findings from the previous analysis. In this assessment, EPA 

determined that any changes due to the updated platform are not likely to be 

substantial and the direction of their effect is indeterminate. Based on this review, 

EPA concluded that a new analysis of the final rule using the updated IPM 

platform would very likely not find materially different impacts; indeed, a new 

analysis would most likely find smaller impacts that those estimated for the 

proposed rule. 

From this review, EPA concluded that new IPM analyses using the IPM V4.10 

MATS platform for the final rule would yield no insights that would alter EPA’s decision 

on the final rule. As a result, given the time and resource requirements of conducting IPM 

runs, EPA decided not to undertake additional IPM analyses using the IPM V4.10 MATS 

platform for the final rule. 

In the following discussion, EPA presents its findings from the IPM analysis 

undertaken for Proposal Option 1. EPA notes that those findings are likely to overstate 

the impact of the final rule – given, in particular, the final rule’s expected lower cost and 
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operational impacts, and increased flexibility in terms of compliance schedule, compared 

to Proposal Option 1. For a detailed discussion of this review, see EA Chapter 7. For a 

detailed discussion of the IPM analysis conducted for the proposed rule, see the 

Economic Analysis for the Economic and Benefits Analysis for Proposed Section 316(b) 

Existing Facilities Rule report (EPA 821-R-11-003) proposed rule EBA. 

The Agency conducted two sets of analysis for the proposed rule: 

 Steady-state impact: EPA looked at output from the analysis run-year 2028, 

which is the first year when all regulated facilities would have achieved 

compliance under the three regulatory options considered in development of 

the proposed existing facilities rule, to assess the regulatory effect during the 

steady-state period of post-compliance operations.134 The Agency conducted 

this analysis for the group of regulated facilities and the electric power sector 

as a whole, including all electric power facilities supplying to the electric 

power grid. 

 Downtime impact: EPA also looked at the results reported for the 2015 IPM 

run-year to assess the impact of technology installation downtime.135 The 

Agency conducted this analysis for the electric power sector as a whole. 

 

134 For the proposed rule analyses, the first year of full compliance was 2018 for Proposal Option 1 and 

2028 for Proposal Option 2. To facilitate comparison of market-level impacts across options, the proposed 

rule analysis focused on 2028 as the steady-state comparison year. 

135 For the Proposal Option 1 analysis, EPA estimated that regulated facilities would install impingement 

mortality control technologies, and experience downtime, during a 5-year window of 2013 through 2017. 

Results for the 2015 IPM run year are indicative of annual effects during those years. 
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Both the steady-state and downtime impact analyses showed that Proposal Option 

1 would have very small effects on the overall electricity market, in general, and the 

group of regulated facilities, in particular, at the national level and at the NERC-region 

level. Specifically, as reported in Exhibit IX-11, in looking at regulated facilities only, the 

analyses showed a very small impact on capacity and electricity generation with total 

available capacity and electricity generation falling by only 0.2 percent and 0.1 percent, 

respectively. Total electricity production costs increased by 0.3 percent of the baseline 

value for the electric power sector as a whole and for the regulated facilities – again, a 

modest amount – with no cost components experiencing large changes. The changes in 

other impact metrics were also very small. 

As reported in Exhibit IX-10, the downtime-impact analysis showed that the 

estimated downtime effects of Proposal Option 1 would also be relatively minor. Total 

costs of electricity production increased by only 0.4 percent, with variable production 

costs per MWh increasing by 0.1 percent, while nearly no change in total revenue. EPA 

also found minimal impacts regionally in this analysis. As detailed in the proposed rule 

EBA, EPA estimated that none of the NERC regions would experience substantial 

changes in the impact metrics under Proposal Option 1. 

As shown in Exhibit IX-11, overall, EPA’s market-level analyses for the proposed 

rule found that Proposal Option 1 would haveThe IPM V4.10_MATS platform provides 

outputs for the NERC regions that lie within the continental United States. This IPM 

platform does not analyze electric power operations in Alaska and Hawaii because these 

operations are not connected to the continental U.S. power grid. The IPM V4.10_MATS 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review*** 

Page 443 of 642 

platform is based on an inventory of U.S. utility- and non-utility-owned boilers and 

generators that provide power to the integrated electric transmission grid, as recorded in 

the EIA 860 (2006) and EIA 767 (2005) databases.136 IPM does not include electric 

power facilities that do not provide power to the U.S. power grid (e.g., some generating 

units at industrial facilities). The IPM V4.10_MATS universe consists of 14,920 

generating units at 4,910 existing electric power facilities, including 520 of the 544 

regulated electric power facilities subject to the final rule.137

This IPM V4.10_MATS platform embeds a baseline energy demand forecast 

from the Department of Energy’s Annual Energy Outlook 2010 (AEO2010), with 

adjustments by EPA to account for the effect of certain voluntary energy efficiency 

programs. This platform also incorporates in its analytic baseline the expected 

compliance response to existing regulatory requirements for the following promulgated 

air regulations affecting the power sector: the final Mercury and Air Toxics Standards 

(MATS) rule; the final Cross-State Air Pollution Rule (CSAPR);138 regulatory SO2 

 

136 In some instances, facility information has been updated to reflect known material changes in a facility’s 

generating capacity since 2006. 

137 Facilities excluded from the IPM analysis include three facilities in Hawaii and one facility in Alaska 

(i.e., areas that are outside the geographic scope of the model), four on-site facilities that are not connected 

to the integrated electric transmission grid, four facilities excluded from the IPM baseline as the result of 

custom adjustments made by ICF, and 12 facilities that did not respond to the 316(b) survey. 

138 EPA’s Cross-State Air Pollution Rule (CSAPR) was promulgated to replace EPA’s Clean Air Interstate 

Rule (CAIR), which had been remanded to EPA in 2008. However, on December 30, 2011, the U.S. Court 

of Appeals for the D.C. Circuit stayed CSAPR pending judicial review and left CAIR in place. On August 

21, 2012 the Court issued an opinion vacating CSAPR and again leaving CAIR in place pending 

development of a valid replacement. On March 29, 2013, the United States filed a petition asking the 

Supreme Court to review the D.C. Circuit’s opinion. Nevertheless, as explained above, CAIR remains in 

effect at this time. In light of the continuing uncertainty on CAIR and CSAPR, EPA determined it would 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review*** 

Page 444 of 642 

emission rates arising from State Implementation Plans (SIP); Title IV of the Clean Air 

Act Amendments; NOx SIP Call trading program; Clean Air Act Reasonable Available 

Control Technology requirements and Title IV unit specific rate limits for NOx; the 

Regional Greenhouse Gas Initiative; Renewable Portfolio Standards; New Source 

Review Settlements; and several state-level regulations affecting emissions of SO2, NOx, 

and mercury that are already in place or expected to come into force by 2017. 

In contrast to the screening-level analyses described earlier, which are static 

analyses and do not account for interdependence of electric generating units in supplying 

power to the electric transmission grid, IPM accounts for potential changes in the 

generation profile of individual electric power facilities and consequent changes in 

market-level generation costs, as a result of the final rule. The model is dynamic in that 

the analysis covers a multiple-decade period with information and decisions in any 

specific period depending on the analysis information and optimization results for the 

entire analysis period. The model is also forward-looking in that it uses forecasts of 

future conditions to make decisions for the present. Finally, in contrast to the screeninglevel analyses in which EPA assumed either no pass through of compliance costs (facility 

and entity cost-to-revenue analyses discussed in Section IX.D.a.1) or full cost passthrough (analysis of potential electricity price effects, Section IX.D.b.1), IPM assesses 

 

not be appropriate or possible at this time to adjust emission projections on the basis of speculative 

alternative emission reduction requirements in 2020. EPA expects that the decision vacating CSAPR and 

leaving CAIR in place has minimal effect on the results of the analysis conducted in support of the final 

rule. 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review*** 

Page 445 of 642 

price and revenue effects from increased costs in competitive wholesale electricity 

markets, where some recovery of compliance costs through increased electricity prices is 

possible but not guaranteed. 

In performing analyses based on the IPM V4.10_MATS platform, EPA used as its 

baseline a projection of electricity markets and facility operations without the final rule 

requirements (baseline case). As discussed above, this baseline accounts for compliance 

with the recently promulgated Federal air rules. EPA then overlaid this baseline with the 

estimated compliance costs and other operating effects – downtime for installation of IM 

technologies at existing units and auxiliary energy requirement to operate cooling towers 

at new units – for regulated facilities under the policy case. 

As discussed in Appendix P of the EA report, the IPM V4.10_MATS platform 

models the electric power market over the 43-year period from 2012 to 2054. Within this 

total analysis period, EPA looked at shorter IPM analysis periods (run-year windows)139 

to assess the effect of the final rule on national and regional electricity markets. 

Specifically, to assess the impact of the final rule during the period when regulated 

facilities temporarily suspend their operation to install compliance technologies – the 

short-term effects analysis or the downtime effects analysis – EPA used results reported 

 

139 Due to the highly data- and calculation-intensive computational procedures required for the IPM 

dynamic optimization algorithm, IPM is run only for a limited number of years. Run years are selected 

based on analytical requirements and the necessity to maintain a balanced choice of run years throughout 

the modeled time horizon. Each run year represents adjacent years in addition to the run year itself. 
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Page 446 of 642 

for the 2020 IPM run year, which represent an 8-year window of 2017 through 2024.140 

The incurrence of downtime may lead to higher electricity generation costs overall, as 

generating units at regulated facilities are taken out of service to complete technology 

installation and other generating units, presumably with higher production costs, are 

dispatched to meet electricity demand. Because of the potential resulting increase in 

electricity generation costs, it is important to examine market-level effects during the 

period in which downtime would occur. 

To assess the longer term effect of the final rule on electricity markets during the 

period after compliance technology is installed at all regulated facilities – the steady-state 

post-compliance period – EPA analyzed results reported for the IPM 2030 run year, 

which represents a 10-year window of 2025 through 2034.141 Effects that may occur 

during this steady-state period include increased electricity production costs at regulated 

facilities and potential permanent losses in generating capacity from early retirement 

(closure) of generating units. Both effects may lead to higher overall electricity 

generation costs through not only the increased production cost in regulated facilities, but 

 

140 As discussed earlier in this document, for the cost and economic impact analyses, EPA assumed that 

electric generators will install IM technologies during the 5-year window of 2018 through 2022. Because 

this technology-installation window falls within the time period captured by the 2020 run year (i.e., 2017 

through 2024), EPA judges that 2020 is an appropriate year to capture the effects of technology-installation 

downtime. 

141 EPA expects this steady-state period to begin in the last year of the technology-installation window, i.e., 

2022, and continue into the future. The 2022 analysis year is captured in the IPM 2020 run year, as opposed 

to the 2030 run year. However, because all analysis years represented by the 2030 run year (i.e., 2025-

2034) fall outside the technology-installation window of 2018 through 2022, EPA judges that 2030 is an 

appropriate year to capture longer term, steady-state effects of the final rule. 
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also through dispatch of higher production cost units to offset capacity losses, reflecting 

the general upward shift in production costs.142

EPA measured the impacts of the final rule as the difference between key 

economic and operational impact metrics between the baseline case and the policy case. 

All analysis results presented below are representative of modeled market conditions in 

the years 2017-2034. While costs are in 2011 dollars, they are reflective of costs in the 

modeled years and are not discounted to the start of EPA’s analysis period of 2013.143 In 

contrast to the earlier statement that the cost and economic impact analysis findings 

presented in this preamble may be underestimates because EPA assumed that no facilities 

with impoundments will install compliance technology, the market-based analysis 

presented in this section reflects the opposite assumption. Namely, despite the final rule’s 

treatment of impoundments, for purposes of this analysis, none of the facilities with 

impoundments are treated as having closed-cycle cooling in the baseline. As a result, to 

the extent that some of these facilities may qualify as having closed-cycle recirculating 

 

142 In seeking to minimize the cost of meeting electricity demand, IPM will tend to shift production away 

from regulated facilities that incur compliance costs, and will shift production to either non-regulated 

facilities, which incur no compliance costs, or to regulated facilities that incur relatively lower compliance 

costs. Any of these changes – whether a simple increase in production costs for previously dispatched units 

or changes in the profile of generating unit dispatch – mean increased total costs for electricity generation, 

compared to the pre-regulation baseline. 

143 In contrast, the social cost estimated in Section IX.C reflects the discounted value of compliance costs 

over the entire 51-year analysis period, as of 2013. Additionally, screening-level analyses presented in 

earlier sections are static analyses and do not account for interdependence of electric generating units in 

supplying power to the electric transmission grid. In contrast, IPM accounts for potential changes in the 

generation profile of steam electric and other units and consequent changes in market-level generation 

costs, as the electric power market responds to higher generation costs for steam electric units due to the 

final rule. 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review*** 

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systems in the baseline, and thus would not need to install compliance technology, the 

costs and economic impacts reported in this section may be overestimated. 

i. Analysis Results for the Year 2030 – To Reflect Steady State, Post-Compliance 

Operations 

For the steady-state analysis (2030), EPA considered impact metrics of interest at 

three levels of aggregation: (1) impact on national and regional electricity markets, (2) 

impact on the group of 520 regulated facilities modeled in IPM, and (3) impact on 

individual 520 regulated facilities. 

Impact on National and Regional Electricity Markets 

For the assessment of market-level impacts, EPA considered six output metrics: 

(1) incremental capacity retirements (closures); (2) changes in capacity retirements as a 

percent of total baseline capacity (3) changes in new capacity additions; (4) changes in 

variable production costs per MWh, calculated as the sum of total fuel and variable O&M 

costs divided by net generation; (5) changes in total generation costs (fuel, variable 

O&M, fixed O&M, and capital); and (6) changes in wholesale electricity prices. 

As shown in Exhibit IX-10, the final rule has small effects on the electricity 

market, on both the national and regional sub-market basis, in 2030. At the national level, 

the analysis shows a total net increase in retired capacity of approximately 1 GW, or less 

than 0.1 percent of the total baseline capacity in 2030 (capacity retirements are discussed 

in greater detail in the next section, Impact on Regulated Facilities as a Group). This 1 

GW of net capacity loss reflects a combination of closures and avoided closures of 
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Page 449 of 642 

generating units. “Avoided closure” means a generating unit that was projected to close 

in the baseline case but remains open in the policy case because of changes in the relative 

operating economics of generating capacity. In some instances an avoided closure can 

result in an avoided full facility closure. Overall, the final rule will lead to early 

retirement of approximately 4 GW of generating capacity and approximately 3 GW of 

avoided closure of capacity otherwise projected to retire by 2030, resulting in a net 

closure of approximately 1 GW of generating capacity. With only one exception, these 

retirements involve older, less efficient generating units with very low capacity utilization 

rates. 

Five of the eight analyzed NERC regions record modest increases in retired 

capacity, with the largest increase, 0.8 percent of baseline retired capacity, projected to 

occur in TRE. One NERC region – SPP – avoids capacity closures, where 1.5 percent of 

capacity otherwise projected to retire in the baseline, becomes a more economically 

viable source of electricity in the policy case due to changes in the relative economics of 

electricity production across the full market, and thus avoids closure.144 Consequently, 

the final rule is not expected to have a material ongoing effect on capacity availability 

and supply reliability at either the national or the NERC region level. 

The 1 GW of retired capacity is replaced by new, more efficient, and less 

polluting capacity. Because the new capacity is more efficient and less costly to run than 

 

144 Avoided closures may occur among facilities that incur no compliance costs under the final rule or for 

which compliance costs are low relative to the costs estimated for other regulated facilities. 
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Page 450 of 642 

the retired capacity, it will run at a higher capacity utilization rate than the retired 

capacity; less new capacity is required to meet electricity demand than the retired 

capacity that it replaces. As shown in Exhibit IX-11, under the final rule, new capacity 

additions increase by 1 GW at the national level; this increase represents 0.5 percent of 

new baseline capacity and 0.1 percent of total baseline capacity (see Exhibit IX-10). This 

increase in new capacity is mostly comprised of combined cycle capacity followed by 

other non-steam capacity, with coal steam capacity additions remaining zero in both the 

baseline case and the policy case. Consequently, this analysis shows that the final rule is 

not likely to impede construction of new combined cycle and coal steam generating 

units.145

As reported in Exhibit IX-10, overall, the final rule has only a slight impact on 

electricity prices. EPA estimated thatFor three out of eight NERC regions, electricity 

prices would increasedecline slightly – by no more than $0.05 per MWh (0.1 percent

during either) in TRE. Electricity prices increase in the steady-state impact period 

orremaining five NERC regions, with the downtime impact period. EPA assessed 

theselargest increase, $0.29 per MWh (0.4 percent), occurring in NPCC. These very 

 

145 As described earlier in this preamble, under the new unit provision of the final rule, new units as defined 

at 125.92 include, stand-alone fossil fuel and combined cycle units. As described in Chapter 6 of the EA, 

the IPM analysis accounts only for compliance costs associated with new units. Further, EPA assigned 

these costs only to coal steam and combined cycle capacity. 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review*** 

Page 451 of 642 

small estimated changes in electricity prices asare essentially within the analytic “noise” 

of the IPMelectricity market modeling system.146

Exhibit IX-10. Impact of final rulea on national markets 

At the national level, total generation costs increase by 0.3 percent of the baseline 

value – again, a very modest amount. Across regions, no NERC region records an 

increase in total costs exceeding 0.5 percent. The change in variable production costs 

($/MWh) – a specific measure of the effect of the final rule on short-run electricity 

generation costs – is nearly zero with no NERC region recording a consequential change. 

Exhibit IX-10. Impact of the Final Rule on National and Regional Markets, at the Year 2030 

NERC Regiona

Total Baseline 

Capacity 

(GW)

Economic Measures 

(all dollar values in $2011)Net 

Changes in Early Retirements

Electric Power SectorChanges in 

Variable Costs

Regulated FacilitiesChanges in 

Total Costs Changes in Electricity Price

Value % Change Value % Change 

 GW

% of 

Total 

Baseline

Capacity 

Policy$2011/MWh Difference% of 

Baseline Mill 2011$ % of Baseline Policy$2011/MWh Difference% of Baseline

Impact During Steady-State Impact Period: 2028 

FRCCTotal 

Capacity (MW)

1,147,571 68 1,147,556 0 -

160.30% -$0.0%03 479,054-0.10% 478,003$51 -1,0510.30% --$0.2%01 0.00%

Existing -597 -0.1%

New Additions 581 0.1%

Early Retirements – Full 

and Partial (MW) 601 0.1% 32,757 33,814 1,056 3.2%

Number of Fully-Retired 

Regulated Facilities NA NA 39 45 6 15.4%

Generation 

(GWh)MRO

4,894,596 76 4,894,626 0 29 

0.00% $0.0%01 2,750,4420.10% 2,746,772$62 -3,6700.40%

-$0.1%21 0.30%

Revenue ($Millions) $325,391 $325,573 $182 0.1% $164,270 $164,103 -$167 -0.1%

 

146 IPM provided estimates of electricity prices effects for each NERC region. 

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Costs ($Millions) $194,107 $194,622 $516 0.3% $88,969 $89,251 $282 0.3%

NPCCVariable 

Production Cost 

($/MWh)

$22.27 73 $22.27 0 0.50% $0.00 0.000% $19.1028 $19.080.20% -$$0.0229 -0.140% 

Impact During 

DowntimeImpact Period: 

2015 (2013-

2017)RFC

237 0 0.10% $0.01 0.00% $157 0.30% $0.15 0.20%

SERCGeneration 

(GWh)

4,319,717274 4,319,5850 -

1310.10% $0.0%02 0.10% $182 0.30% $0.08 0.10%

Revenue ($Millions) $219,872 $219,899 $27 0.0%

Costs ($Millions) $148,964 $149,535 $571 0.4%

Variable 

Production Cost 

($/MWh)SPP

$22.2659

$22.28-

1

$0.01

0.-1.50% $0.02 0.10% $31 0.30% -$0.01 0.00%

TRE 98 1 0.80% -$0.01 0.00% $48 0.30% -$0.05 -0.10% 

WECC 220 0 0.00% $0.00 0.00% $9 0.00% $0.03 0.00% 

Total 1,106 1 0.10% $0.00 0.00% $568 0.30% N/A 

a

The Proposal Option 1 is similar to the final rule, and thus, the IPM analysis done for that option serves as a proxy for 

IPM analysis for the final rule.a FRCC (Florida Reliability Coordinating Council), MRO (Midwest Reliability Organization), NPCC (Northeast Power Coordination 

Council), RFC (ReliabilityFirst Corporation), SERC (Southeastern Electricity Reliability Council), SPP (Southwest Power Pool), TRE (Texas Reliability Entity), and WECC (Western 

Electricity Coordinating Council)

Exhibit IX-11. Impact of Final Rule on electricity pricesa,b

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NER

C 

Regio

nc

Exhibit IX-11. Steady-State 

Impact: 2028Impact of the 

Final Rule on New Capacity 

(GW), at the Year 2030

Downtime Impact: 2015

Capacity Type

Bas

eline 

Valu

e 

% ChangeFinal 

Rule

Value % Change

Base

line ValuePolicy Difference 

% 

Cha

nge

Ba

sel

ine

P

oli

cy

Dif

fer

en

ce

Coal 

Stea

mFR

CC

$6

5.6

6

$6

5.

65

-

$

0

.

0

1

0

.

0

%

$68.95 $69.03

$0.08 0.1%NA

Combined Cycle 7

5 76 1 0.8% 

MROCombustion 

Turbine

$

5

3

.

8

8

6

$53.886 $0.00

0

.

0

% 

$3

8.

92

$

3

8.

9

4

$0

.0

3

0.

1

%

Hydro 0 0 0 NA 

Nuclear 0 0 0 NA 

O/G Steam 0 0 0 NA 

NPCCOther 

Non-Steama

$

7

6

.

9

7

$77.0625 $0.09

0

.

1

% 

$6

7.

05

$

6

7.

0

4

-

$0

.0

1

0.

0

%

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NER

C 

Regio

nc

Exhibit IX-11. Steady-State 

Impact: 2028Impact of the 

Final Rule on New Capacity 

(GW), at the Year 2030

Downtime Impact: 2015

Capacity Type

Bas

eline 

Valu

e 

% ChangeFinal 

Rule

Value % Change

Base

line ValuePolicy Difference 

% 

Cha

nge

Ba

sel

ine

P

oli

cy

Dif

fer

en

ce

2

5

RFCOther 

Steamb

$

5

4

.

9

9

9

$55.029

$

0

.

0

3

0.

1

%

$4

0.

51

$

4

0.

5

1

$0

.0

0

0.0% 

TotalSERC

$

5

6

.

6

3

1

1

4

$

5

6

.

6

2

1

1

5

-$0.01 0.

0

%

$4

7.1

2

$

4

7.

1

6

$0

.0

4

0.1% 0.5%

SPP $51.45 

$5

1.4

5 

-

$0.01 0.0% $47.66 $47.70 $0.03 0.1%

TRE $61.62 

$6

1.6

1 

-

$0.01 0.0% $60.35 $60.31 -$0.05 -0.1%

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NER

C 

Regio

nc

Exhibit IX-11. Steady-State 

Impact: 2028Impact of the 

Final Rule on New Capacity 

(GW), at the Year 2030

Downtime Impact: 2015

Capacity Type

Bas

eline 

Valu

e 

% ChangeFinal 

Rule

Value % Change

Base

line ValuePolicy Difference 

% 

Cha

nge

Ba

sel

ine

P

oli

cy

Dif

fer

en

ce

WEC

C $57.93 

$5

7.

91 

-

$0.02 0.0% $54.34 $54.34 $0.00 0.0%

a

The Proposal Option 1 IPM is similar to the final rule, and thus, the IPM analysis done for that option serves as a 

proxy for IPM analysis for the final rule. b IPM does not model two NERC regions: Alaska Systems Coordinating 

Council (ASCC) and Hawaii Coordinating Council (HICC). 

c

 FRCC – Florida Reliability Coordinating Council; MRO – Midwest Reliability 

Organization; a Other non-steam capacity includes wind, solar, pumped storage, and fuel cell. 

b

 Other steam capacity includes biomass, geothermal, municipal solid waste, fossil waste, landfill gas, tires, and nonfossil waste.NPCC – Northeast Power Coordinating Council; RFC – ReliabilityFirst 

Corporation; SERC – Southeastern Electric Reliability Council; SPP – Southwest Power 

Pool; TRE - Texas Reliability Entity, and WECC – Western Energy Coordinating 

Council.

3Impact on Regulated Facilities as a Group 

EPA used the same IPM V4.10_MATS analysis results for 2030 as those used to 

assess market-level impacts described above; however, this analysis considers the effect 

of the final rule only on regulated facilities modeled in IPM (i.e., 520 facilities). For this 

analysis, EPA considered four output metrics: (1) incremental capacity closures; (2) 

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changes in capacity closures as a percent of total baseline capacity; (3) changes in total 

generation; and (4) changes in variable production costs per MWh. 

As shown in Exhibit IX-12, for the group of regulated facilities, the impact of the 

final rule is overall slightly greater than that observed over all generating units in the IPM 

universe (i.e., market-level analysis discussed in the preceding section). This difference is 

due to the fact that in the electricity market as a whole, impacts on regulated facilities, 

which become less competitive compared to facilities that do not incur compliance costs, 

are offset by changes in capacity and energy production at the other electric power 

facilities. Nevertheless, the impact on the group of regulated facilities remains small. For 

instance, while there is essentially no change in total available capacity for the overall 

electricity market at the national level, for the group of regulated facilities, total available 

capacity falls by only 0.4 percent (2 GW). At the regional level, five NERC regions incur 

loss in total capacity, with the largest percentage loss of 2.8 percent and the largest 

absolute loss of 0.9 GW occurring in the NPCC region. 

The 2 GW of capacity loss at regulated facilities reflects a combination of 

closures and avoided closures of generating units in the universe of regulated facilities. 

Some unit closures result in full facility closures (i.e., all generating units at a facility 

close), while others result in only partial facility closures (i.e., some, but not all, 

generating units at a facility close). For avoided closures, a generating unit projected to 

close in the baseline case but remains open under the policy case, in some instances 

resulting in an avoided full facility closure. Overall, 22 generating units close (4 GW) and 

12 generating units avoid closure (2 GW) in the policy case, resulting in net closure of 10 
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Page 457 of 642 

generating units (approximately 2 GW) in Electricity Market Analysis - Final Rule 

analysis. The 22 generating unit closures reflect retirement of nine units at six full-closure 

facilities (2 GW) and retirement of 13 units at six partial-closure facilities (2 GW). With 

only one exception, these retirements involve older, less efficient generating units with 

very low capacity utilization rates. 

At the national level, for the group of regulated facilities, total generation at 

regulated facilities declines by less than 2 GWh or approximately 0.1 percent of baseline 

generation in these facilities. The MRO and SERC regions record slight increases in 

generation essentially amounting to zero percent of baseline generation at regulated 

facilities in these regions, with the remaining five NERC regions recording a reduction in 

electricity generation of no more than 0.4 percent in FRCC. 

Over all regulated facilities, there is essentially no change in variable production 

costs ($/MWh) at the national level, while at the NERC region level, the change does not 

exceed 0.2 percent for any of the regions. These findings of very small effects confirm 

EPA’s assessment that the assessed capacity closures among regulated facilities are of 

little economic consequence at both the national and regional levels. 

Exhibit IX-12. Impact of Electricity Market Analysis Options on the Group of Regulated Facilities, 

at the Year 2030

NERC 

Regiona

Baseline 

Capacity 

(MW) 

Net Change in Early 

Retirements / Closures Change in Generation 

Change in Variable 

Production Cost 

Capacity 

(MW) 

% of 

Baseline GWh 

% of 

Baseline $2011/MWh

% of 

Baseline

FRCC 30,794 203 0.7% -527 -0.4% -$0.08 -0.2% 

MRO 31,747 0 0.0% 30 0.0% $0.01 0.1% 
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Exhibit IX-12. Impact of Electricity Market Analysis Options on the Group of Regulated Facilities, 

at the Year 2030

NERC 

Regiona

Baseline 

Capacity 

(MW) 

Net Change in Early 

Retirements / Closures Change in Generation 

Change in Variable 

Production Cost 

Capacity 

(MW) 

% of 

Baseline GWh 

% of 

Baseline $2011/MWh

% of 

Baseline

NPCC 30,977 855 2.8% -25 0.0% $0.00 0.0% 

RFC 126,905 223 0.2% -619 -0.1% $0.00 0.0% 

SERC 142,840 476 0.3% 3 0.0% $0.02 0.1% 

SPP 24,487 -530 -2.2% -411 -0.3% $0.01 0.0% 

TRE 38,378 808 2.1% -163 -0.1% -$0.02 -0.1% 

WECC 34,788 0 0.0% -8 0.0% $0.00 0.0% 

Total 460,917 2,035 0.4% -1,721 -0.1% $0.00 0.0% 

a

 FRCC (Florida Reliability Coordinating Council), MRO (Midwest Reliability Organization), NPCC (Northeast 

Power Coordination Council), RFC (ReliabilityFirst Corporation), SERC (Southeastern Electricity Reliability 

Council), SPP (Southwest Power Pool), TRE (Texas Reliability Entity), and WECC (Western Electricity 

Coordinating Council) 

Impact on Individual Regulated Facilities 

Results for the group of 520 regulated facilities as a whole may mask shifts in 

economic performance among individual facilities incurring compliance costs under the 

final rule. To assess potential facility-level effects, EPA analyzed facility-specific 

changes between the baseline case and the final rule for the following metrics: (1) 

capacity utilization (defined as annual generation (in MWh) divided by [capacity (MW) 

times 8,760 hours]) (2) electricity generation, and (3) variable production costs per MWh. 

Exhibit XI-13 presents the estimated number of regulated facilities with specific 

degrees of change in operations and financial performance. Under the final rule, this 

analysis shows that most facilities experience only slight effects – i.e., no change or less 
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Page 459 of 642 

than a 1 percent reduction or 1 percent increase. Only six facilities are estimated to incur 

a reduction in capacity utilization and 13 facilities a reduction in generation of at least 1 

percent, with only five facilities estimated to incur an increase in variable production 

costs per MWh of at least 1 percent. These facilities represent approximately 1 percent of 

520 regulated facilities analyzed in IPM. 

Exhibit IX-13. Impact of the Electricity Market Analysis - Final Rule on Individual Regulated 

Facilities at the Year 2030 (Number of Regulated Facilities With Indicated Effect)

Economic Measures 

Reduction 

No 

Change Increase N/Ab,c

 3% 

1and 

<3% <1% <1% 

1and 

<3%  3% 

Change in Capacity Utilizationa 1 5 45 340 35 2 0 92 

Change in Generation 9 4 37 345 29 2 2 92 

Change in Variable Production 

Costs/MWh 2 1 70 86 242 4 1 114 

a

 The change in capacity utilization is the difference between the capacity utilization percentages in the baseline 

and policy cases. For all other measures, the change is expressed as the percentage change between the 

baseline and post-compliance values. 

b

 Facilities with status changes in either the baseline case or the policy case were excluded from these 

calculations. Specifically, there are 17 full baseline facility closures, 59 partial baseline facility closures, four 

avoided partial facility closures, six partial policy facility closures, and six partial policy facility closures. 

c

 The change in variable production cost per MWh could not be developed for 22 facilities with zero generation 

in either the baseline case or the policy case. 

ii. Analysis Results for 2020 – To Capture the Effect of Technology-Installation 

Downtime 

This section presents market-level results for the final rule for the 2020 IPM run 

year, which represents 2017 through 2024. As discussed above, this IPM run year 

captures the period when regulated facilities are expected to install compliance 

technologies under the final rule. Of particular importance as a potential impact, the 
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Page 460 of 642 

additional downtime from installation of compliance technologies could manifest as 

increased electricity production costs resulting from the dispatch of higher-productioncost generating units during the period when units are taken offline to install compliance 

technologies. Because these effects are of most concern in terms of potential impact on 

national and regional electricity markets, this section presents results only for the overall 

electricity market and does not present results for the subset of regulated facilities. 

As shown in Exhibit IX-14, the estimated effects of technology-installation 

downtime under the final rule are small. At the national level, total production costs 

increase by 0.4 percent. At the regional level, these costs increase in all NERC regions, 

with MRO and SPP recording the largest increase of 0.6 percent. 

At the national level, variable production costs ($/MWh) increase by 

approximately 0.2 percent. While the effect on variable production costs varies across 

NERC regions, this effect is small overall, with the largest increase of less than 0.4 

percent occurring in FRCC. While electricity prices increase in all NERC regions, the 

magnitude of that increase is generally small, ranging from $0.15 per MWh (0.3 percent) 

in MRO and WECC to $0.56 per MWh (0.9 percent) in FRCC. 

Exhibit IX-14. Short-Term Effect of Technology Installation Downtime on National Electricity 

Market Under the Final Rule – 2020

NERC 

Regiona

Change in 

Generation 

Change in Variable 

Production Cost Change in Total Costs 

Change in Electricity 

Price 

2011$/

MWh

% of 

Baseline

2011$/

MWh

% of 

Baseline

Million 

2011$

% of 

Baseline

2011$/

MWh

% of 

Baseline

FRCC -108 0.0% $0.13 0.4% $51 0.5% $0.56 0.9% 

MRO 52 0.0% $0.03 0.2% $64 0.6% $0.15 0.3% 

NPCC -88 0.0% $0.05 0.2% $31 0.3% $0.18 0.3% 
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Exhibit IX-14. Short-Term Effect of Technology Installation Downtime on National Electricity 

Market Under the Final Rule – 2020

NERC 

Regiona

Change in 

Generation 

Change in Variable 

Production Cost Change in Total Costs 

Change in Electricity 

Price 

2011$/

MWh

% of 

Baseline

2011$/

MWh

% of 

Baseline

Million 

2011$

% of 

Baseline

2011$/

MWh

% of 

Baseline

RFC 447 0.0% $0.03 0.1% $164 0.4% $0.19 0.4% 

SERC -369 0.0% $0.04 0.1% $185 0.4% $0.27 0.6% 

SPP -53 0.0% $0.08 0.3% $56 0.6% $0.18 0.4% 

TRE 0 0.0% $0.08 0.3% $64 0.5% $0.21 0.4% 

WECC 33 0.0% $0.04 0.2% $39 0.1% $0.15 0.3% 

Total -88 0.0% $0.05 0.2% $652 0.4% N/A

a

 FRCC (Florida Reliability Coordinating Council), MRO (Midwest Reliability Organization), NPCC 

(Northeast Power Coordination Council), RFC (ReliabilityFirst Corporation), SERC (Southeastern Electricity 

Reliability Council), SPP (Southwest Power Pool), TRE (Texas Reliability Entity), and WECC (Western 

Electricity Coordinating Council) 

EPA recognizes any capacity outages estimated to occur in conjunction with installation 

of compliance technologies at existing units will require outage coordination by the 

system operator or other planning authority. Where possible, these outages would be 

scheduled in concurrence with normal scheduled maintenance outages. Permit 

authorities are provided flexibility to tailor compliance timelines. This flexibility will 

ensure that any adverse impact on local electric reliability as a result of this rule will be 

avoided. Facilities would receive workable construction schedules from permit writers 

that will allow schedule outages for installation without adversely affecting electric 

supply reliability. 
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2. Manufacturers 

This section presents EPA’s estimated economic impacts on manufacturers for the 

final rule and the other options EPA considered. These analyses assess the impact of 

regulatory requirements on the financial performance of regulated facilities (facility-level 

analysis) and the entities that own them (entity-level analysis). Similarly to the electric 

generators analysis, for the manufacturers facility-level and entity-level analyses, the 

Agency assumed that facilities would pass none of their compliance costs forward to 

customers as price increases, i.e., all compliance costs will be absorbed by regulated 

facilities and their parent entities. For details on the cost-pass-through (CPT) analysis for 

information on this assumption, see the EA, Appendix K. EPA developed and used 

sample weights to extrapolate impacts assessed initially at the level of a sample of 

facilities to the full population of regulated facilities. For information on the development 

and use of sample weights, see EA Appendix H. 

a. Facility-Level Impact Analysis for Manufacturers 

EPA conducted two separate facility-level analyses for manufacturers: (1) a 

standalonestand-alone cost-to-revenue screener analysis and (2) a facility closure and 

financial stress short of closure test. For the cost-to revenue screener test, shown in 

Exhibit IX-1215, EPA divided the after-tax, annualized compliance cost by facility-level 

revenue. Under the final rule, EPA found that of 569500 Primary Manufacturing Industry 

facilities, 556496 incur costs less than one percent of revenue, 13four incur costs between 

one and three percent, and none incur costs greater than 3 percent. For the 10nine Other 

Industries facilities, EPA estimated that nineeight facilities would incur costs less than 
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Page 463 of 642 

one percent and one would incur costs between one and three percent of revenue. For 

Proposal Option 4, all Primary Manufacturing Industry facilities (569500 facilities) and 

Other Industry facilities (10nine facilities) incur costs less than one percent of revenue. 

Under Proposal Option 2, 556491 Primary Manufacturing Industry facilities incur costs 

less than one percent and 13nine facilities incur costs between one and three percent, 

while nineseven Other Industry facilities incur costs less than one percent and, one 

facility incurs costs between one and three percent, and one facility incurs costs greater 

than three percent. 

Exhibit IX-1215. Facility-level after-tax annual compliance costs as a percentage of cost-torevenue analysis results

Option 

Number of facilities with a cost-to-revenue ratio ofa

<1% 

≥1 

and <3% ≥3% 

Primary manufacturing industries 

Proposal Option 4 

569500 0 0 

Final Rule 

562496 74 0 

Proposal Option 2 

556491 139 0 

Other industries 

Proposal Option 4 

109 0 0 

Final Rule 

98 1 0 

Proposal Option 2 

87 1 1 
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a. EPA conducted this analysis for 579 facilities in the Primary Manufacturing Industries and 10 facilities in 

the Other Industries. Note, these facility counts and analysis exclude facilities identified as baseline closures 

in the severe impact analysis, which is described below.

For the second analysis, EPA assessed how compliance costs would likely affect 

financial performance and condition of approximately 500the 509 manufacturers147 using 

two measures: (1) facility closures (severe impacts) and associated losses in revenue and 

employment, and (2) financial stress short of closure (moderate impacts). 

For the analysis of severe impacts, EPA identified a facility as a regulatory 

closure if it would have operated under baseline conditions but would not be financially 

viable under the new regulatory requirements and the costs of the final rule leading to 

that finding exceeded a threshold of 0.1 percent of revenue. Specifically, the Agency 

examined the facility’s going-concern value before and after meeting regulatory 

requirements. EPA used a discounted cash flow framework in which after-tax cash flow 

is discounted at an estimated cost of capital to calculate the going concern value of the 

facility.148 In conjunction with the discounted cash flow analysis, EPA tested whether 

annualized costs exceeded 0.1 percent of revenue by dividing the after-tax, annualized 

total compliance cost by facility-level revenue. If this analysis found that the facility’s 

 

147 This is a sample-weighted estimate of the number of Manufacturersmanufacturers, calculated using 

economic weights. This number excludes 70 facilities estimated to be at substantial risk of financial failure 

regardless of any additional financial burden that might result from the final rule or other options 

considered in development of this rule. For details see EA Appendix H. 

148 This after-tax cash flow analysis conducted for Manufacturersmanufacturers is similar in concept to the 

cash flow analysis conducted for Generatorselectric generators through the IPM analysis. 
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Page 465 of 642 

business value would become negative as a result of estimated compliance costs and the 

annualized cost of compliance exceeded 0.1 percent of revenue, EPA classified the 

facility as a regulatory closure. 

For facilities estimated not to close under the severe-impact test, EPA conducted a 

moderate-impact test to assess whether any would experience financial stress short of 

closure as the result of regulatory requirements. (e.g., higher costs of capital borrowing).

EPA used two financial performance measures to test for occurrence of financial stress: 

(1) interest coverage ratio and (2) pre-tax return on assets. The Agency compared these 

measures before and after compliance with regulatory requirements against industryspecific performance thresholds for the two financial measures. For a facility, ifIf both 

measures for a facility exceeded the threshold in the baseline, and at least one measure 

fell below the threshold in the post-compliance case, EPA counted this as a moderate 

impact based on the rule. 

Exhibit IX-1316 presents the results from the severe-impact and moderate-impact 

analyses. EPA estimated that no facilities would be aat risk of closure as a result of the 

final rule and that 12 facilities wouldcould experience financial stress, short of closure. 

For Proposal Option 4, EPA also estimated no closures, while moderate impacts are 

significantly lower, estimated at two facilities. Under Proposal Option 2, EPA estimated 

that one facility would be at risk of closure, while the financial stressmoderate impact

finding is the same as for the final rule: 12 facilities. Again, this analysis is conducted 

assuming that all the costs are borne by the facility and cannot be passed along, an 

assumption that is highly unlikely to be true, as many of these facilities are in industries 
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Page 466 of 642 

where there is some market power and barriers to entry. Thus, these tests present worst 

case scenario results.

Exhibit IX-1316. Facility impacts and compliance costs for manufacturersmanufacturersd

Proposed Option 4 Final Rule 

Proposed Option 2

c

2c

Primary manufacturing industriesa

Number of Facilities Operating in Baseline 500 500 500 

Number of Closures (Severe Impacts) 0 0 1 

Percentage of Facilities Closing 0% 0% 0% 

Number of Facilities with Moderate Impacts 2 12 12 

Percentage of Facilities with Moderate Impacts 1% 3% 3% 

Other industriesb

Number of Facilities Operating in Baseline 9 9 9 

Number of Closures (Severe Impacts) 0 0 0 

Percentage of Facilities Closing 0% 0% 0% 

Number of Facilities with Moderate Impacts 0 0 0 

Percentage of Facilities with Moderate Impacts 0% 0% 0% 

a

 Primary Manufacturing Industries include facilities in the Aluminum, Chemicals and Allied Products, Food and Kindred 

Products, Paper and Allied Products, Petroleum Refining, and Steel industries. 

b

 Other Industries include cooling water-dependent facilities in industries whose principal operations lie in businesses 

other than the electric power industry or the Primary Manufacturing Industries. 

c

. Under Proposal Option 2, the percentage of facilities closing is 0.3 percent.

d

 The analysis assumes no cost pass through.

b. Entity-Level Impact Analysis 

EPA also examined the impact of regulatory requirements on entities that own 

complyingregulated manufacturers facilities. An entity that owns multiple facilities could 

be adversely affected because of the cumulative burden of regulatory requirements the 

facilities face. For this analysis, a parent entity is the domestic parent entity with the 

largest ownership share in a complyingregulated facility. For each identified parent 
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entity, EPA aggregated facility-level, annualized, after-tax compliance costs to the level 

of the parent entity and compared these entity-level costs to entity-level revenue. 

Similarly to electric generators, EPA used cost-to-revenue thresholds of 1 and 3 percent 

as thresholds for categorizing levels of impacts. 

EPA considered two cases, based on two sets of entity-level weights (see the EA, 

Appendix H for details on development of entity-level weights).. These cases, which are 

described in the EA, Appendix H, provide a range of estimates for the number of entities 

incurring compliance costs and the costs incurred by any entity owning a 

complyingregulated facility. EPA conducted this analysis for 509 facilities in the primary 

manufacturing industries and 12 facilities in other industries.149 For information on the 

methodology used for the entity-level cost-to-revenue analysis, see the EA, Chapter 5. 

Exhibit IX-1417 presents the results from the entity-level analysis for these two 

cases. EPA estimated that between 120 and 337 entities own 521 complyingregulated

facilities. Under the final rule, the majoritybetween 90 and 95 percent of all entities are 

estimated to incur compliance costs of less than 1 percent of revenue (between 90 and 95 

percent of all entities).. This is true also for Proposal Option 2. Under Proposal Option 4, 

even more entities are also expected to incur compliance costs of less than 1 percent of 

revenue (between 94 and 96 percent of all entities). 

 

149 This is a sample-weighted estimate of the number of manufacturer facilities, calculated using technical 

weights. This number excludes 67 facilities estimated to be at substantial risk of closure regardless of any 

additional financial burden that might result from the regulatory options under consideration. 
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Exhibit IX-1417. Entity-level after-tax annual compliance costs as a percentage of cost-to-revenue analysis 

results

Option 

Not analyzed due to 

lack of revenue 

information 

Number of entities with a cost-to-revenue ratio of 

< 1% ≥ 1 % and < 3% ≥ 3%

# % # % # % # % 

Primary Manufacturing Industries 

Case 1: Lower bound estimate of number of entities that own complyingregulated facilities; upper bound estimate of total 

compliance costs that an entity may incurb

Proposal 

Option 4 5 4% 113 94% 2 2% 0 0% 

Final 

Rule 5 4% 108 90% 6 5% 1 1% 

Proposal 

Option 2 5 4% 108 90% 6 5% 1 1% 

Case 2: Upper bound estimate of number of entities that own complyingregulated facilities; lower bound estimate of total 

compliance costs that an entity may incurc

Proposal 

Option 4 12 4% 324 96% 1 0% a

 0 0% 

Final 

Rule 12 4% 319 95% 6 2% 0 0% 

Proposal 

Option 2 12 4% 319 95% 6 2% 0 0% 

a. The percentage of entities with impacts greater than or equal to 1 percent and less than 3 percent is less than 0.5 

percent 

b. The total number of entities under Case 1 is 120. 

c. The total number of entities under Case 2 is 337. 

E. Employment Effects 

To consider employment effects at the national level, EPA looked at the potential 

effects of the final rule and other options considered in development of this rule. This 

analysis considers the employment effects of meeting compliance requirements in the 
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Page 469 of 642 

directly regulated industry sectors. EPA relied on a study conducted by Morgenstern, 

Pizer, and Shih that explores the theoretical and empirical relationships between 

employment and compliance costs of environmental regulation.150 Morgenstern et al. 

identified and accounted for three factors affecting employment in a regulated industry in 

response to a regulation. First, complying with environmental regulations increases 

production costs, which raises market prices. Higher prices reduce consumption (and 

production), which, in turn, reduce demand for labor in the regulated industry (demand 

effect). Second, as the basis for costs to produce the same output increase, plants add 

some combination of more capital and labor to comply with the regulation. For example, 

pollution abatement activities require additional labor services to produce the same level 

of output (cost effect). Third, post-regulation production technologies might be more or 

less labor intensive (i.e., more/less labor is required per dollar of output) (factor-shift 

effect). The demand effect factor is unambiguously negative, the cost effect is 

unambiguously positive, and the factor-shift effect could be positive or negative. The 

overall employment impact of any given regulation, therefore, is theoretically 

indeterminate. 

Morgenstern et al. estimated a model based on data for four highly 

polluting/regulated industries—pulp and paper, plastic material, petroleum, and steel—to 

 

150 For details on this study see Morgenstern, Richard D. & Pizer, William A. & Shih, Jhih-Shyang, 2002. 

"Jobs Versus the Environment: An Industry-Level Perspective," Journal of Environmental Economics and 

Management, Elsevier, vol. 43(3), pages 412-436, May. 
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examine regulations’ effect on employment. This model generates a net change in the 

number of jobs per each additional $1 million in annual pollution-abatement spending (in 

1987 dollars) for each of the four analyzed industries and as an average across all four 

industries. The Morgenstern et al. study results do not cover all the industries subject to 

today’s final rule. Morgenstern et al. did not estimate coefficients for the electric 

generating industry, and did estimate coefficients for three of the six primary 

manufacturing industries: the paper and allied products, petroleum refining, and steel 

sectors. For the industries not covered, EPA would only be able to use the average total 

effect coefficient of 1.55 jobs per $1 million ($1987). For the specific industries covered, 

EPA would be able to use the industry-specific coefficients (-1.13, 2.17, and 0.53 jobs 

per $1 million [$1987], respectively, for paper and allied products, petroleum refining, 

and steel sectors) to directly assess employment effects in these sectors. If EPA had 

applied these coefficients to the sector-specific compliance costs of today’s rule, the job 

effects in some industries would be positive, while in others the job effects would be 

statistically insignificant or negative. Given the uncertainty associated with applying the 

results for a limited set of industries that did not include the electric power generation 

sector, EPA has decided not to use the Morganstern, Pizer and Shih results in a 

quantitative analysis. EPA has therefore determined that the employment effects of this 

rule are not likely to be very substantial. 

To study employment effects of this rule, EPA considered the potential effects of 

the final rule, focusing on the impacts of meeting compliance requirements in the directly 

regulated industry sectors: the Electric Power Industry, and selected Primary 
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Page 471 of 642 

Manufacturing Industries, including Aluminum, Chemicals and Allied Products, Food 

and Kindred Products, Paper and Allied Products, Petroleum Refining, and Steel 

Manufacturing. 

When the economy is at full employment, an environmental regulation is unlikely 

to have much impact on net overall U.S. employment; instead, labor would primarily be 

shifted from one sector to another. These shifts in employment impose an opportunity 

cost on society, approximated by the wages of the employees, as regulation diverts 

workers from other activities in the economy. In this situation, any effects on net 

employment are likely to be transitory as workers change jobs (e.g., some workers may 

need to be retrained or require time to search for new jobs, while shortages in some 

sectors or regions could bid up wages to attract workers). 

On the other hand, if a regulation comes into effect during a period of high 

unemployment, a change in labor demand due to regulation may affect net overall U.S. 

employment because the labor market is not in equilibrium. Schmalansee and Stavins151

point out that net positive employment effects are possible in the near term when the 

economy is at less than full employment due to the potential hiring of idle labor resources 

by the regulated sector to meet new requirements (e.g., to install new equipment) and 

new economic activity in sectors related to the regulated sector. In the longer run, the net 

 

151 Schmalansee, Richard, and Robert N. Stavins. “A Guide to Economic and Policy Analysis of EPA’s 

Transport Rule.” White paper commissioned by Exelon Corporation, March 2011 (Docket EPA-HQOAR-2011-0135-0054). 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review*** 

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effect on employment is more difficult to predict and will depend on the way in which the 

related industries respond to the regulatory requirements. As Schmalansee and Stavins 

note, the magnitude of the effect on employment could vary over time, region, and sector, 

and positive effects on employment in some regions or sectors could be offset by 

negative effects in other regions or sectors. For this reason, they urge caution in reporting 

partial employment effects because it can “paint an inaccurate picture of net employment 

impacts if not placed in the broader economic context.” 

In that spirit, unlike the analysis for the proposed rule, for the final rule EPA is 

not estimating quantitative employment impacts and instead, including only a qualitative 

discussion. 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 input-output 

analysis 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.152 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 

 

152 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). 
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employment analysis of the proposed rule. Thus, today’s final rule EA includes a 

qualitative discussion highlighting the variety of potential adjustments in the labor market 

that may follow the rulemaking. 

To elaborate on the difficulty of deriving high quality estimates of how 

environmental regulations will impact net employment, the task requires consideration of 

labor demand in both the regulated and environmental protection sectors, as well as labor 

supply more generally. Economic theory predicts that the net effect of an environmental 

regulation on labor demand in regulated sectors could be positive or negative; the 

direction of the outcome depends on the magnitude of output and substitution effects, 

explained further in the EA. Peer-reviewed econometric studies that use a structural 

approach, applicable to overall net effects in the regulated sectors, indicate that such 

effects, whether positive or negative, have been small and have not affected employment 

in the national economy in a significant way (Berman and Bui 2001, Morgenstern, Pizer 

and Shih 2002). Effects on labor demand in the environmental protection sector seem 

likely to be positive. 

In aggregate, the environmental protection sector is likely to experience a 

temporary increase in jobs created as more compliance technology systems are designed, 

manufactured, and installed attributable to the final rule. In addition, because of regional 

variation in consumption patterns and the presence of regulated facilities and supporting 

industries, short- and long-run employment effects likely will vary across the United 

States. It is possible that positive net employment effects will occur in the near term due 
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Page 474 of 642 

to the hiring of idle labor resources by the regulated sectors to plan for and meet new 

technology control requirements rather than diverting workers from other productive 

employment. However, it is also possible that in the long run, as the economy returns to 

full employment, any changes in employment in the regulated sectors due to the final rule 

will be offset by employment changes in other sectors. These dynamics compound the 

uncertainty in estimating employment effects for a substantial number of years into the 

future. 

Even if regulated facilities are able to reduce the impact of regulatory 

requirements by changing their production processes in the post-rule environment, 

production costs may still be higher compared to those before the rule. As a result, 

regulated facilities may seek to increase their product prices in response to the higher 

production costs. For example, attempts by electric generators to recover increases in 

electricity generation costs, however small, are likely to result in higher electricity rates. 

The impact of this increase will vary by region, customer group (e.g., industrial, 

commercial, transportation, and residential), and by industry, depending on the 

electricity-use intensity.153 Further, the extent to which electric generators are able to pass 

their costs to consumers through higher electricity rates, will vary by region. Specifically, 

electric generators operating in regions where electricity prices remain regulated under 

 

153 See the EA Chapter 6: Electricity Market Analysis for assessment of the impacts of increased 

production costs on wholesale electricity prices and Chapter 4: Economic Impact Analysis – Electric 

Generators for analyses of the impacts on retail rates by customer group. 
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the traditional cost-of-service rate regulation framework may be able to recover 

compliance cost-based increases in increased rates.154 However, cost recovery is less 

certain for electric generators operating in States where electric power generation has 

been deregulated, and will depend on the competitive circumstances of specifically 

affected facilities. 

Overall, the long-run changes in employment will likely depend on how the 

electric power industry, primary manufacturing industries, and other industries adjust in 

response to the new regulatory requirements, and on the upstream and downstream 

effects of those adjustments on the rest of the economy, as well as the overall state of the 

economy and labor markets. The long-run employment effects in the directly affected 

sectors will depend on a number of economic factors. These factors include changes in 

labor requirements to operate the infrastructure in general and compliance technology in 

particular at regulated facilities, the potential to change production processes to become 

less dependent on cooling water, availability of alternative technologies to meet 

compliance requirements, and changes in demand for the outputs of the directly affected 

sectors. Because these and many other interrelated factors include data and methodology 

limitations, it is difficult to fully assess the employment impacts of the final rule. 

 

154 However, even for electric generators operating under traditional rate regulation, the recovery of cost 

increases through increased rates is not certain, and will depend on additional factors such as the facility 

ownership structure and operating model, approval of public utility commissions, and the importance and 

role of market mechanisms in dispatching production of electricity across generating units. See Chapter 2A

of the EA for additional discussion. 
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However, based on the available evidence from several peer-reviewed econometric 

studies mentioned above that are applicable to net effects in the regulated sectors and that 

closed-cycle recirculating systems was rejected as national BTA for entrainment, EPA 

expects that employment impacts of today’s rule are not likely to be substantial. 

X. Benefits Analysis 

A. Introduction 

 This section presents EPA’s estimates of the national environmental benefits of 

the final existing facilities rule and other options considered by EPA. This section 

describes how EPA calculated values for those benefits it could monetize. EPA did not 

rely on the results of its stated preference survey in estimating the benefits of today’s 

rule. It also presents descriptive information for those benefits for which EPA could not 

develop a monetary value. The benefits EPA assessed occur because of reductions in 

impingement and entrainment at cooling water intake structures affected by the 

rulemaking and changes in greenhouse gas emissions at regulated facilities. Impingement 

occurs where fish and other aquatic life are trapped on equipment as they enter the 

cooling water intake structure. Entrainment occurs where aquatic organisms, including 

eggs and larvae, are drawn into the cooling system, passed through the heat exchanger, 

and discharged back into the source water bodywaterbody. Impingement and entrainment 

kill or injure large numbers of aquatic organisms across all life stages. On the basis of 

entrainment data presented in facility studies, EPA assumes a mortality rate of 

100 percent for entrained individuals. Mortality is then reduced on the basis of the 

efficiency of technology in place in reducing mortality rates, or by reducing levels of 
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impingement and entrainment.155 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 water bodies resulting in healthier aquatic environments. In 

turn, this healthier aquatic environment directly improves welfare for individuals using 

the affected aquatic resources, generating use benefits such as increases in the value of 

recreational and commercial fisheries or increases in property values. Reductions in 

impingement mortality and entrainment also improve welfare for individuals without use 

of the affected resources, generating nonuse benefits, such as improved ecosystem 

function and resource bequest values. Section D provides an overview of the types and 

sources of benefits EPA anticipated, how EPA estimated these benefits are estimated, and 

the level of benefits that the final rule and other options EPA considered for the rule 

would achieve. 

EPA derived national benefit estimates for the final rule and other options 

considered options from a series of regional studies representing a range of water 

bodywaterbody types and aquatic resources. Section B provides detail on the regional 

study design. Section C describes the impingement and entrainment effects and Section D 

presents the national benefits estimates. 

The methodologies used to estimate benefits are largely built on those used to 

estimate benefits for the remanded Phase II and Phase III and the proposed existing 

 

155 See the discussion in Section III on entrainment mortality data and assumptions. 
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facilities rules. In addition to updating these analyses, EPA more fully investigated the 

effects of impingement mortality and entrainment on T&E species, incorporated benefits 

from greenhouse gas reductions, and improved its estimation of nonuse benefits. The 

Benefits Analysis document for the final existing facilities rule (referred to as the BA) 

provides detailed descriptions of the new methodologies EPA used to analyze the benefits 

of regulatory options, and provides references to (i) Part A of the 2004 Regional Benefits 

Analysis for the Final Section 316(b) Phase II Rule, and (ii) Part A of the 2006 Regional 

Benefits Analysis Document for the Final Section 316(b) Phase III Existing Facilities 

Rule for analyses using similar methodologies. 

The BA provides EPA’s benefit estimates for the final rule and considered 

options. EPA relied on information collected in the 2000 Sectionsection 316(b) Industry 

Surveysindustry surveys (the Industry Screener Questionnaire (SQ) and the Detailed 

Industry Questionnaire (DQ)) on cooling water systems and intake structures already in 

place to estimate the number of regulated facilities under regulatory options considered 

for the final existing facilities rule. For the analysis of complyingregulated electric 

generators, EPA used information from 656 complyingregulated electric generating 

facilities that responded to the Sectionsection 316(b) Surveysindustry surveys on cooling 

water systems and intake structures already in place. Because the DQs were sent to a 

sample of the manufacturing industries that use cooling water, the respondents were 

assigned sample weights designed to represent other facilities in other manufacturing 

industries that were not covered in the survey. All complyingregulated facilities have a 

DIF of at least 2 mgd. EPA estimated regional benefits from the sample of facilities for 
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which EPA has sufficient DQ information to estimate the environmental impacts of 

regulatory options. The environmental impacts from the set of explicitly analyzed 

facilities were then extrapolated to the universe of facilities in a region using statistical 

weights developed for this analysis. National benefits are estimated as the sum of the 

regional benefits. 

As described above at Section IX, the findings presented in this section assume 

that all facilities with impoundments will qualify as having closed-cycle recirculating 

systems in the baseline. For purposes of this analysis, EPA did not estimate IM&E 

reductions for these facilities under the final rule and other options considered; however, 

these facilities remain subject to today’s rule and are assigned administrative costs. To 

the extent that some of these facilities do not qualify as having closed-cycle cycle 

recirculating systems in the baseline, the monetized benefits reported in this section may 

be underestimated. EPA notes that the vast majority of these facilities occur in the Inland 

benefits region. Any underestimation in monetized benefits due to the treatment of 

facilities with impoundments is likely to be minor because commercial fishing benefits 

and nonuse benefits are not estimated for the Inland region. 

B. Regional Study Design 

EPA evaluated the benefits of today’s rule in seven study regions.156 Regions 

were defined on the basis of ecological similarities within regions (e.g., freshwater versus 

 

156 Benefits associated with changes in greenhouse gas emissions were estimated for the nation as as whole. 
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marine, similar communities of aquatic species), and on characteristics of commercial 

and recreational fishing activities. The seven study regions are: California,157 North 

Atlantic, Mid Atlantic, South Atlantic, Gulf of Mexico, Great Lakes, and Inland. The five 

coastal regions EPA identified (California, North Atlantic, Mid-Atlantic, South Atlantic, 

and Gulf of Mexico) correspond to those of the National Oceanic and Atmospheric 

Administration’s National Marine Fisheries Service. The Great Lakes region includes 

Lake Ontario, Lake Erie, Lake Huron (including Lake St. Clair), Lake Michigan, Lake 

Superior, and the connecting channels (Saint Mary’s River, Saint Clair River, Detroit 

River, Niagara River, and Saint Lawrence River to the Canadian border) as defined in 33 

U.S.C. 1268, Sec. 118(a)(3)(b). The Inland region includes all remaining facilities that 

withdraw water from freshwater lakes, rivers, and reservoirs (, including inland facilities 

in coastal states).. Notably, of the 435 facilities that are on freshwater streams or rivers, 

30 percent (132) have average actual intake flow that is greater than 5 percent of the 

mean annual flow of the source waters, which is a significant amount of the source water 

flow. During periods of low river flow, or during periods of higher than average 

withdrawals of cooling water, the proportionate withdrawal of source waters could be 

much higher. Thus, the potential for adverse environmental impacts could increase 

dramatically during these periods. The number and total operational intake flow of all 

316(b) facilities by study region are presented in Exhibit X-1. 

 

157 The California region includes facilities in State of California and four facilities in Hawaii. No coastal 

facilities are in Oregon, and one facility in Washington is classified as a baseline closure. 
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Exhibit X-1. Number of surveyed facilities and total mean operational flow),, by region, 

Region 

Number of Surveyed 

Facilitiesa

Flow (billions of gallons per day) 

Non-Recirculating 

Facilitiesb

Recirculating 

Facilities Total Flow 

Californiac 21 10.65 0.00 10.65

Great Lakes 50 16.24 0.24 16.47

Inlandd 566 121.82107.56 3.8018.06 125.62

Mid-Atlantic 46 24.69 0.07 24.76

Gulf of Mexico 22 10.1814 0.0005 10.18

North Atlantic 21 5.93 0.00 5.93

South Atlantic 12 5.91 0.05 5.96

All Regions 738 195.42181.12 4.1618.46 199.58

a This table presents unweighted facility counts and flow for surveyed facilities (excluding baseline closures). The 

regional study design for the benefits analysis uses weights based on flow rather than facility counts. EPA did not 

developeddevelop weighted facility counts by benefits region. The “All Regions” total of 738 surveyed facilities includes 

532 electric generating facilities and 206 manufacturing facilities, excluding baseline closures. The total (weighted) 

estimated universe of facilities, excluding baseline closures, is 1,065 facilities. 

bb Recirculating facilities are facilities with closed-cycle cooling or impoundments that qualify as closed-cycle cooling.

Non-recirculating facilities includesinclude facilities with CWIS classified as once-through, combination, or “other.” 

Recirculating facilities are facilities with closed-cycle cooling.. 

c

 The California region includes four facilities in Hawaii. There are no coastal facilities in Oregon and the one coastal 

facility in Washington is classified as a baseline closure. 

d A facility in Texas has intakes in both the Inland and Gulf of Mexico regions. It is included in the Inland region in the 

table to prevent the double counting of facilities. 

EPA obtained estimates of regional impingement mortality and entrainment by 

extrapolating impingement mortality and entrainment observed at 9798 facilities with 

impingement and entrainment 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. Extrapolation was 

conducted on the basis of AIF reported for the period 1996–1998 by facilities in response 
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to EPA’s Section 316(b) Detailed Questionnaire and Short Technical Questionnaire. 

Chapter 3 of the BA provides details of the extrapolation procedure. Because the goal of 

the analysis was to provide estimates of impingement mortality and entrainment at 

regional and national scales, EPA recognizes that these averages may not reflect the 

substantial variability at individual facilities. In spite of this variability, EPA determined 

that this extrapolation is a reasonable basis for developing estimates of regional- and 

national-level benefits for the purposes of the final existing facilities rule. 

C. Physical Impacts of Impingement Mortality and Entrainment 

 EPA based the benefits analysis on facility-provided impingement mortality and 

entrainment monitoring data. Facility data consist of records of impinged and entrained 

organisms sampled at intake structures and include organisms of all ages and life stages. 

Sampling protocols were not standardized across facilities. Facility protocols differed in 

sampling methods and equipment used, the number of samples taken, sampling duration, 

and the unit of time and volume of intake flow used to express impingement mortality 

and entrainment. To standardize estimates across facilities, EPA converted sampling 

counts into annual impingement mortality and entrainment. Using standard fishery 

modeling techniques,158 EPA constructed models that combined facility-derived 

 

158 Ricker, W.E. 1975. Computation and interpretation of biological statistics of fish populations. Fisheries 

Research Board of Canada, Bulletin 191; Hilborn, R. and C.J. Walters. 1992. Quantitative Fisheries Stock 

Assessment, Choice, Dynamics and Uncertainty. Chapman and Hall, London and New York; Quinn, T.J., 

II. and R.B. Deriso. 1999. Quantitative Fish Dynamics. Oxford University Press, Oxford and New York; 

Dixon, D.A. 1999. Catalog of Assessment Methods for Evaluating the Effects of Power Plant Operations 

on Aquatic Communities. Electric Power Research Institute (EPRI) Final Report. Report number TR112013. 
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impingement mortality and entrainment counts with life history data from the scientific 

literature to derive annual estimates of the following: 

 Individuals – the number of individual organisms impinged and entrained by 

facility intakes. Under this metric, eggs, larvae, juvenile, and adult organisms are 

counted as equivalent individuals. 

 A1Es (age-one equivalent losses)—the number of individual organisms of 

different ages impinged and entrained by facility intakes, standardized to 

equivalent numbers of 1-year-old fish. A conversion rate between all life history 

stages and age 1 is calculated using species-specific survival tables based on life 

history schedule and age-specific mortality rates. An individual younger than age 

1 is a fraction of an age-one equivalent; an individual older than age 1 represents 

more than one age-one equivalent. EPA finds it appropriate to use the A1E 

measure because information in the record indicates that an overwhelming 

majority of eggs, larvae and juveniles do not survive into adulthood and the A1E 

calculations adjust for differences in survivorship based on species and agespecific mortality rates. EPA recognizes that using A1Es simplifies a complex 

ecological situation, because some of the smaller fish would provide an ecological 

benefit to other species as food even if they would not survive to adulthood. 

Recognizing this as one nonmonetized benefit in the analysis, using an A1E 

approach is the most reasonable approach available because to date, there is 

insufficient data to account for the extent to which organisms that do not survive 
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to adulthood provide a benefit to other organisms which can be reliably 

monetized. 

 Forgone fishery yield—pounds of commercial fish harvest and numbers of 

recreational fish and shellfish that are not harvested because of impingement 

mortality and entrainment. EPA used the Thompson-Bell equilibrium yield 

model159 to convert impingement mortality and entrainment to forgone fishery 

yield, assuming that (1) impingement mortality and entrainment reduces the 

future yield of harvested adults, and (2) reductions in impingement mortality and 

entrainment rates will lead to an increase in harvested biomass. The general 

procedure involves multiplying age-specific harvest rates by age-specific weights 

to calculate an age-specific expected yield. 

 Biomass production forgone—biomass that would have been produced had 

individuals not been impinged or entrained,160 calculated for all species from 

species- and age-specific growth rates and survival probabilities. It refers to the 

mass of impinged and entrained organisms that would have served as valuable 

components of aquatic food webs, particularly as an important food supply to 

other aquatic species. 

 

159 Ricker, W.E. 1975. Computation and interpretation of biological statistics of fish populations. Fisheries 

Research Board of Canada, Bulletin 191. 

160 Rago, P.J. 1984. Production forgone: An alternative method for assessing the consequences of fish 

entrainment and impingement losses at power plants and other water intakes. Ecological Modeling, 24(1-

2): 79-111. 
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Estimates of forgone fishery yield include direct and indirect losses of impinged 

and entrained species that are harvested. Indirect losses represent the yield of harvested 

species lost because of reductions in prey availability according to a simple trophic 

transfer model (i.e., forage species).161 Chapter 3 of the BA contains detailed 

methodology for these analyses. 

 Studies from individual facilities may underestimate or overestimate impingement 

mortality and entrainment rates at those facilities. For example, facility studies typically 

focus on a subset of fish species affected by impingement mortality and entrainment, 

resulting in other species being ignored. The number of individuals lost to impingement 

mortality and entrainment is then underestimated. Estimating the magnitude of this 

underestimate is not possible because of the low number of replicate studies. Moreover, 

studies often do not count early life stages of organisms that are more difficult to identify. 

In addition, many of the impingement mortality and entrainment studies used by the 

Agency were conducted more than 30 years ago, prior to the improvement of aquatic 

conditions that have resulted from implementation of the CWA as well as stateState and 

local laws and efforts. In locations where water quality was degraded at the time of 

impingement mortality and entrainment sampling relative to current conditions, the 

abundance and diversity of fish populations might have been depressed, resulting in low 

impingement mortality and entrainment estimates. Therefore, use of these data may 

 

161 Indirect losses account for about 10 percent of commercial and recreational harvest reductions at 

baseline. 
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underestimate the magnitude of current impingement mortality and entrainment. 

Alternatively, studies could have been conducted in locations where local fish 

populations are now lower than they were when the study occurred. Such a shift in fish 

populations might have occurred because of natural variability in populations, because of 

other anthropogenic effects (i.e., over-harvesting), or because of competition from 

invasive species. In such cases, the use of these data may overestimate the magnitude of 

current impingement mortality and entrainment. 

EPA’s use of linear methods for projecting losses to fish and shellfish in the water 

bodywaterbody may also overstate or understate impacts. Nevertheless, the data from 

facility studies are the best means to estimate the relative magnitude of impingement 

mortality and entrainment nationwide. Exhibit X-2 presents EPA’s estimates of baseline 

annual impingement mortality and entrainment, and reductions in annual impingement 

mortality and entrainment estimated to occur under the final rule and other options 

considered. Impingement mortality and entrainment reductions under the final rule are 

less than the reductions under Proposal Option 2 and greater than reductions under 

Proposal Option 4. Unlike the analysis of Proposal Option 2, EPA did not model the 

entrainment reductions forfrom cooling tower installation under the final rule and 

Proposal Option 4 because these would be based on site-specific determinations of BTA, 

which are not possible to predict with information EPA has today. EPA estimated a small 

amount of entrainment losses under the final rule and Proposal Option 4 due to the 

assumed installation of variable speed pumps at some facilities to achieve compliance via 

the low velocity compliance alternative. 
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Exhibit X-2. Baseline annual IM&E and annual reductions in IM&E for existing units at all facilities subject to 

the final rule 

Loss mode a

Reduction in annual IM&E by regulatory option b,c

Baseline Annual IM&E 

Proposal Option 4 

Final Rule – Existing 

Units

Proposal Option 2 

Individuals (millions) 

IM 378.8419.9 394.1441.3 458.2511.9 486.3568.6

E 423.2399.8 17221,693.9 339,261.2335,447.6 497,152.9316.3

IM&E 802.0819.7 2117.02,135.2 339,719335,959.4 497,639.2884.8

Age-One Equivalents (millions) 

IM 550.0612.8 571.6647.5 662.6748.2 700.6824.2

E 1.54 4.65 889.73 1,089.9106.7

IM&E 551.5614.2 576.3652.0 1,552.3637.5 1,790.5931.0

Forgone Fishery Yield (million lbs) 

IM 10.812.6 1113.3 13.115.4 14.216.9

E 0.10 0.1 35.57 52.09

IM&E 10.812.6 1113.4 48.651.1 66.269.8

Production Forgone (million lbs) 

IM 112.8129.7 117.2136.5 135157.2 143.1174.8

E 0.65 2.54 345.6337.0 447.2451.8

IM&E 113.4130.3 119.7138.9 480.8494.2 590.3626.6

a

 IM = impingement mortality; E = entrainment; IM&E = impingement mortality and entrainment 

b

 IM&E Effects by Option: Proposal Option 4 = impingement mortality limitations based on modified traveling screens for 

all facilities with flow greater than 50 mgd; Final Rule = impingement mortality limitationsstandards based on modified 

traveling screens for all facilities with flow greater than 2 mgd; Proposal Option 2 = intake flow commensurate with closedcycle cooling for facilities that have a DIF of greater than 125 mgd and impingement mortality limitations based on 

modified traveling screens for all facilities with flow greater than 2 mgd. 

c

 The totals presented here do not include IM&E reductions associated with new units. Estimated IM&E reductions 

associated with the new unitsunit provision of the final rule are presented in Exhibit X-4. 

Exhibit X-3 presents EPA’s estimates of annual impingement mortality and 

entrainment for final rule and other considered options by category of fish species. 

Estimates of annual forgone fishery yield include both direct losses of harvested species 

and indirect losses from reductions in prey fish species. Organisms convert (on average) 

only about 10% percent of the mass of food they consume into additional tissue mass. 
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Thus, although essential to maintain ecosystem function, the vast majority of biomass 

moving through food webs does not reach higher trophic levels associated with 

commercial and recreational species and harvest. Instead, the biomass of prey species is 

metabolized and used for predator locamationlocomotion, reproduction, and tissue repair. 

Accordingly, the portion of impingement mortality and entrainment that are counted 

within the forgone harvest metric) represent only a small percentage of all organisms 

experiencing impingement mortality and entrainment at cooling water intake structures. 

Neither forage species nor the unlanded portion of recreational and commercial species 

were assigned direct use values in this analysis, although losses in forage species did 

contribute to the overall losses in recreational and commercial species as noted above. 

Because the majority of annual impingement mortality and entrainment include 

unharvested recreational and commercial fish and forage fish, considering nonuse values 

in the final rule benefits analysis is particularly important. If nonuse values were not 

considered at all, only two to three percent of fish losses would be represented in 

monetized benefits. 

Exhibit X-3. Distribution of annual baseline IM&E and reductions in IM&E by species category, for individual 

organisms and Age-1 equivalents, at existing units for the final rule and options considered

IM&E Metric a

Reduction in IM&E by regulatory option b,c

Baseline IM&E Proposal 

Option 4 

Final Rule – 

Existing Units 

Proposal Option 

2 

Individuals (millions) 

All Species 802.0819.7 2,117.0135.2 339,719335,959

.4 

497,639.2884.8
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Forage Species 591.5607.9 1,441.5423.6 229,399.5224,3

23.1

327,836.5325,0

69.1

Commercial & Recreational Species 210.5211.8 705711.5 110,319.9111,636

.3

169,802.7172,81

5.8

Commercial & Recreational Harvest 

(millions of fish) 

14.316.1 15.017.1 42.044.7 50.454.0

Lost Individuals with Direct Use Value 

(%) 

1.7897% 0.7180% 0.01% 0.01%

Age-One Equivalents (millions) 

All Species 551.5614.2 576.3652.0 1,552.3637.5 1,790.5931.0

Forage Species 467.9528.2 487560.8 1,177.8258.7 1,334.6459.7

Commercial & Recreational Species 83.685.9 88.491.2 374.5378.8 380.7471.3

Commercial & Recreational Harvest 

(millions of fish) 

14.316.1 15.017.1 42.044.7 50.454.0

A1E Losses with Direct Use Value (%) 2.5963% 2.6062% 2.7173% 2.8180% 

a

 IM&E = impingement and entrainment; A1E= age-one equivalent; 

b

 IM&E Effects by Option: Proposal Option 2 = impingement mortality limitations based on modified traveling screens for 

all facilities with flow greater than 50 mgd; Final Rule = impingement mortality limitationsstandards based on modified 

traveling screens for all facilities with flow greater than 2 mgd; Proposal Option 2 = intake flow commensurate with 

closed-cycle cooling for facilities that have a DIF of greater than 125 mgd and impingement mortality limitations based on 

modified traveling screens for all facilities with flow greater than 2 mgd. 

c

 The totals presented here do not include IM&E reductions associated with new units. Estimated IM&E reductions 

associated with the new unitsunit provision of the final rule are presented in Exhibit X-4. 

In addition to the final rule and other options analyzed for existing units (Proposal 

Option 4 and Proposal Option 2), EPA analyzed requirements for new units at existing 

facilities. EPA’s new unit provision in the final rule for new units establishestablishes

entrainment requirements for all new stand-alone units at existing facilities and where the 

turbine and condenser are newly built or replaced, except in the case of high energy 

efficiency units. EPA could not directly apply the extrapolation methodology used for 

existing units because facility-specific information was not available for new units. 
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Instead, EPA estimated impingement mortality and entrainment reductions on the basis of 

impingement mortality and entrainment reductions per million gallons per day from the 

analysis of existing units. The estimated reduction in impingement mortality and 

entrainment for the new unitsunit requirement is summarized in Exhibit X-4. 

Exhibit X-4. Baseline annual IM&E and annualAnnual reductions in IM&E by species category for the final 

rule for new units 

IM&E metric a Reduction in IM&E b

Individuals (millions) 

All Species 8,420.9867.2

Forage Species 5,547.3566.1

Commercial and Recreational Species 2,873.7301.1

Commercial and Recreational Harvest (millions of fish) 0.61

Lost Individuals with Direct Use Value (%) 0.01% 

Age-One Equivalents (millions) 

All Species 21.82.3

Forage Species 15.41.7

Commercial and Recreational Species 6.40.7

Commercial and Recreational Harvest (millions of fish) 0.61

A1E Losses with Direct Use Value (%) 2.8687% 

a

 A1E= age-one equivalent; IM&E = impingement mortality and entrainment 

b

 Impingement mortality and entrainment reductions increase throughout the compliance period. The values presented here 

reflect the peak reductions achieved in 2059, the final year of the compliance period. 

IM&E Effects: entrainment requirements for all stand-alone or units where the turbine and condenser are newly built or 

replaced (note: these number will drop as the high energy efficiency units are pulled out from the rule)..

D. National Benefits of the Final Rule and Options Considered 

1. Overview 

Economic benefits of the final rule and other options considered for regulated 

facilities can be categorized broadly into use and nonuse benefits of goods and services. 

Use values include benefits that pertain to the human use (direct or indirect) of affected 

fishery resources. Use values reflect the value of all current direct and indirect uses of a 
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good or service. Direct use benefits can be further categorized according to whether 

affected goods and services are traded in the market (i.e. commercially captured fish are 

traded, recreational catch is not). Likewise, indirect use benefits can be linked to direct 

goods and services. For example, reductions in impingement mortality and entrainment 

of forage fish will enhance the biomass of species targeted for commercial (market) and 

recreational (nonmarket) uses. It could also affect property values. 

Nonuse benefits are those benefits that are independent of any current or 

anticipated human use of a resource. Nonuse benefits reflect human values associated 

with existence and bequest motives. In other words, these values reflect the value the 

public places on something simply as a result of its existence. or natural functioning. EPA 

estimated the economic benefits from national regulatory options using a range of 

valuation methods. Commercial fishery benefits were valued using market data. 

Recreational angling benefits were valued using a benefits transfer approach based on 

revealed and stated preference data. To estimate indirect use benefits from reduced 

impingement mortality and entrainment of forage species, EPA used a simple trophic 

transfer model. This model translated changes in impingement mortality and entrainment 

of forage fish into changes in the harvest of commercial and recreational species. All 

benefits for fish saved under today’s final rule are estimates on the basis of projected 

numbers of age-one equivalent fish, converted to harvestable age equivalents on a 

species-by-species basis for those commercial species analyzed. 

EPA calculated the monetary value of use benefits of the final rule and other 

options considered for existing facilities using two discount rate values: 3 and 7 percent. 
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All dollar values presented are in 2011 dollars. Because avoided fish deaths occur mainly 

in fish that are younger than harvestable age (eggs, larvae, and juveniles), the main 

benefits from avoided impingement mortality and entrainment would be realized 

typically 3 to 4 years after their avoided death. A detailed description of the approaches 

used to address this is in Appendix C of the BA. 

Neither forage species nor the unlanded portion of recreational and commercial 

species were assigned direct use values in this analysis. Their potential value to the public 

is derived from several alternative sources: their indirect use as both food and breeding 

population for those fish that are harvested; and other non-usenonuse value. These 

includeThe nonuse value includes individuals’ WTP (willingness to pay) for the 

protection of fish based on a sense of altruism, stewardship, bequest, or vicarious 

consumption; and their support of ecosystem stability and function. To estimate a subset 

of nonuse benefits from reducing impingement mortality and entrainment of forage 

species and landed and unlanded commercial and recreational species, EPA conducted a 

benefits transfer using a nonmarket valuation study of aquatic ecosystem improvements. 

This effort generated partial estimates of nonuse values for resource changes for one 

species expected to result in the North Atlantic and Mid-Atlantic benefits regions from 

the final rule and considered options. EPA was unable to use benefits transfer to estimate 

reliable nonuse valuations for changes expected to result in other study regions.a species 

that represents less than one percent of adverse environmental impacts. 

EPA developed and fielded an original stated preference survey to estimate total 

WTP for improvements to fishery resources affected by impingement mortality and 
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entrainment from regulated 316(b) facilities (75 FR 42438, July 21, 2010). Preliminary 

results of the stated preference survey were described in a Notice of Data Availability (77 

FR 34927, June 12, 2012). EPA presents preliminary benefits estimates based on the 

stated preference survey in the BA document to demonstrate progress on this effort. In 

the absence of final survey results, EPA estimated partial nonuse benefits for the final 

rule using the benefits transfer approach from proposal. EPA updated the proposal results 

to incorporate additional stock assessment data for winter flounder, the species used as 

the basis for the analysis. Due to the challenges associated with estimating nonuse 

benefits, some nonuse benefits are described only qualitatively. 

2. Timing of Benefits 

Discounting refers to the economic conversion of future benefits and costs to their 

present values, accounting for the fact that individuals value future outcomes less than 

comparable near-term outcomes. Discounting enables a valid comparison of benefits and 

costs that occur across different periods. EPA used discounting to account for differences 

in the timing across benefits and costs under the final rule and optionoptions considered. 

EPA estimated the expected benefits of the final rule once the rule takes full effect, then 

used discounting to account for delays in the realization of benefits. Two different delays 

affect the timing of benefits under the final rule and options considered. 

First, facilities will begin to incur costs prior to technology installation. Facilities 

will face regulatory requirements once the rule is effective, but it will take time for 

requirements to be developed and for the required technology to be installed. Analyzed 

facilities are assigned a technology installation year which considers facility 
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characteristics and technology being installed. EPA assumed that facilities installing 

impingement technology tend to complete technology installation sooner than facilities 

installing closed-cycle cooling. (for other options considered). The assignment of 

technology installation years is speculative on EPA’s part, because EPA does not have 

sufficient data on hand to project the schedules that Directors will set for facilities. See 

Chapter 3 of the Economic AnalysisEA document for the final existing facilities rule 

(referred to as the EA) for details on EPA’s development of technology installation 

years. EPA effectively discounts benefits to a greater extent than costs to account for the 

lag between the incurrence of costs and the realization of benefits. 

Second, an additional time lag will result between technology implementation and 

use values via increased fishery yields. This lag occurs because several years could pass 

between the time an organism is spared from impingement mortality or entrainment and 

the time of its potential harvest. For example, a larval fish spared from entrainment (in 

effect, at age 0) could be caught by a recreational angler at age 3, meaning that a 3-year 

time lag arises between the incurred technology cost and the realization of the estimated 

recreational benefit. Likewise, if a 1-year-old fish is spared from impingement and is then 

harvested by a commercial waterman at age 2, there is a 1-year lag between the incurred 

cost and the subsequent commercial fishery benefit. To account for this growth period, 

EPA applied discounting by species groups in each regional study. Note that nonuse 

values (depending on how they are measured) do not necessarily need to be discounted 

similarly. 
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3. Recreational Fishing Valuation 

a. Recreational Fishery Methods 

To estimate recreational benefits of the final options, EPA developed a benefits 

transfer approach on the basis of a meta-analysis of recreational fishing valuation studies 

designed to measure the various factors that determine WTP for catching an additional 

fish per trip. Regional benefits are summarized as follows (for details, see Chapter 7 of 

the BA): 

1. Estimate the annual forgone catch of recreational fish (number of fish) 

attributable to impingement mortality and entrainment under current conditions. 

2. Estimate the marginal value per fish using a benefit transfer function based on a 

meta-analysis of recreational fishing studies. 

3. Multiply the forgone catch by the marginal value per fish to estimate the total 

annual value of the forgone catch. 

4. Estimate the annual value of reductions in the forgone catch attributable to the 

regulatory analysis options. 

5. Discount the time path of benefits at 3 and 7 percent to reflect the time lag 

between impingement mortality and entrainment reductions and increased 

harvests. 

b. Estimated Benefits to Recreational Anglers 

Decreasing impingement mortality and entrainment increases the number of fish 

available to be caught by recreational anglers, thereby increasing angler welfare. Exhibit 

X-5 shows the estimated benefits resulting from reduced impingement mortality and 
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entrainment under today’s final existing facilities rule and other options that EPA 

considered. The total annualized recreational fishing benefits for all regions at existing 

units of existing facilities for the final rule (impingement mortality and entrainment 

combined) are $12.818 million using a 3 percent discount rate and $9.814 million using a 

7 percent discount rate. Annual recreational fishing benefits for other options considered 

range from $12.217 to $37.343 million using a 3 percent discount rate and $9.413 million 

to $26.430 million using a 7 percent discount rate. 

Exhibit X-5. Annual recreational fishing benefits from eliminating or reducing IM&E at existing facilitiesunits 

at existing facilities for the final rule and other options considered

Regulatory option a

Increased harvest 3% discount rate 7% discount rate 

(million fish) (million 2011$) (million 2011$) 

Proposal Option 4 5.36.1 12.217.1 9.412.6

Final Rule – Existing 

Units 

56.5 12.818.2 9.813.5

Proposal Option 2 19.420.5 37.343.0 26.429.5

Baseline 23.425.3 68.678.8 6572.0 

a

 IM&E Effects by Option: Proposal Option 4 = impingement mortality limitations based on modified traveling 

screens for all facilities with flow greater than 50 mgd; Final Rule = impingement mortality 

limitationsstandards based on modified traveling screens for all facilities with flow greater than 2 mgd; 

Proposal Option 2 = intake flow commensurate with closed-cycle cooling for facilities that have a DIF of 

greater than 125 mgd and impingement mortality limitations based on modified traveling screens for all 

facilities with flow greater than 2 mgd. 

4. Commercial Fishing Valuation 

Reductions in impingement mortality and entrainment at cooling water intake 

structures are expected to benefit the commercial fishing industry. By reducing the 

number of fish killed, the number of fish available for harvest is expected to increase. 
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The next section summarizes the methods EPA used to estimate benefits to the 

commercial fishing sector. The section after that presents the estimated value of 

commercial fishing benefits. 

a. Commercial Fishing Valuation Methods 

The total loss to the economy from impingement mortality and entrainment 

impacts on commercially harvested fish species is determined by the sum of changes in 

both producer and consumer surplus. EPA assumed a linear relationship between stock 

and harvest, such that if 10 percent of the current commercially targeted stock were 

harvested, 10 percent of the commercially targeted fish lost to impingement mortality and 

entrainment would have been harvested absent impingement mortality and entrainment. 

The percentage of fish harvested is based on data of historical fishing mortality rates. 

Producer surplus provides an estimate of the economic damages to commercial 

fishers, but welfare changes can also be expected to accrue to final consumers of fish and 

to commercial consumers (including processors, wholesalers, retailers, and middlemen) if 

the projected increase in harvest is accompanied by a change in price. The analysis of 

market impacts involves the following steps (for details, see Chapter 6 of the BA): 

1. Assessing the net welfare changes for fish consumers due to changes in fish 

harvest and the corresponding change in fish price. 

2. Assessing net welfare changes for fish harvesters due to the change in total 

revenue, which could be positive or negative. 

3. Calculating the increase in net social benefits when the fish harvest changes by 

combining the welfare changes for consumers and harvesters. 
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For a more detailed description of the methodology for commercial fishing, see 

Chapter 6 of the BA. 

b. Commercial Fishing Valuation Results 

 Exhibit X-6 presents the estimated annual commercial fishing benefits attributable 

to the proposed options. The results reported include the total reduction in losses in 

pounds of fish, and the value of this reduction discounted at 3 and 7 percent. Total 

estimated annualized commercial fishing benefits for the United States for the final rule 

are $0.9 million using a 3 percent discount rate and $0.7 million using a 7 percent 

discount rate. Annual commercial fishing benefits for other options considered range 

from $0.89 million to $4.03.9 million using a 3 percent discount rate and $0.67 million to 

$2.87 million using a 7 percent discount rate. EPA estimated the expected price changes 

from eliminating baseline levels of impingement mortality and entrainment and found 

them to be small, ranging from 0.2 to 2.5 percent. 

Exhibit X-6. Annual commercial fishing benefits from eliminating or reducing IM&E at existing unitunits at 

regulatedexisting facilities for the final rule and other options considered

Regulatory option a

Increased harvest 3% discount rate 7% discount rate 

(million fishlbs) (million 2011$) (million 2011$) 

Proposal Option 4 9.05.3 0.89 0.67

Final Rule – Existing 

Units 

9.5.7 0.9 0.7 

Proposal Option 2 22.614.0 4.03.9 2.87

Baseline 27.017.3 8.0 7.62

a

 IM&E Effects by Option: Proposal Option 4 = impingement mortality limitations based on modified traveling 

screens for all facilities with flow greater than 50 mgd; Final Rule = impingement mortality 

limitationsstandards based on modified traveling screens for all facilities with flow greater than 2 mgd; 

Proposal Option 2 = intake flow commensurate with closed-cycle cooling for facilities that have a DIF of 
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Page 499 of 642 

greater than 125 mgd and impingement mortality limitations based on modified traveling screens for all 

facilities with flow greater than 2 mgd. 

5. Nonuse Benefits 

Aquatic organisms with no direct use benefits account for the majority of cooling 

water intake structure losses (Exhibit X-3). Although many peopleindividuals may not 

use a particular waterbody waters for recreation or fishing, peopleindividuals 

nevertheless may value improvements in that waterbody. To quantitatively assess the 

ecological gains from the final rule and other options considered, EPA took two 

approaches – a benefits transfer approach and a stated preference surveyboth of the only 

two approaches available for quantifying nonuse benefits – a benefits transfer approach 

and a stated preference survey. It is not necessary to use a stated preference survey 

approach to calculate benefits; however, important nonuse benefits can be missed by not 

using a stated preference survey approach. So EPA took both approaches, but relied on 

only the benefits transfer approach for the benefits analysis supporting the final rule. The 

benefits transfer approach relies on the existence of previously published studies with 

values that can be transferred; in instances where nonuse is potentially significant, as is 

the case here, previously published studies would only include nonuse value if they 

adopted a stated preference approach. 

EPA used a benefit transfer approach to partially monetize nonuse benefits 

associated with reductions in impingement mortality and entrainment of fish, shellfish, 

and other aquatic organisms under the categorical regulatory options for the North 
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Atlantic and Mid-Atlantic benefits regions. EPA applied estimated values from a study 

conducted in Rhode Island; these estimates are likely to be more representative of nonuse 

values held by individuals residing in the Northeast United States and less accurate in 

other regions. EPA was unable to identify comparable studies conducted in other regions 

that could be used to estimate nonuse values. Chapter 8 of the BA provides further detail 

on this analysis. 

The preferred techniques used to estimatingestimate total resource values 

(including both use and nonuse values), in general, are to use benefits transfer or to 

conduct a stated preference survey. There are many studies in the environmental 

economics literature that quantify benefits or WTP associated with various types of water 

quality and aquatic habitat changes. However, none of these studies allows the isolation 

of non-market WTP associated with quantified reductions in impingement mortality and 

entrainment for forage fish or unlanded portion of commercial and recreational species. 

a. Non-UseNonuse Benefits Transfer 

EPA identified a recent stated preference survey of Rhode Island residents that is 

closely related to the 316(b) policy context. The study results have been published in 

multiple scientific journals and books including Johnston et al.162 and Zhao et al.163 Both 

 

162 Johnston, R.J. E.T. Schultz, E.T., K. Segerson, E.Y. Besedin, and M. Ramachandran. 2012. Enhancing 

the content validity of stated preference valuation: The structure and function of ecological indicators. Land 

Economics, 1: 102-120. 

163 Zhao, M., Johnson, R. J. and Schultz, E. T. 2013. What to Value and How? Ecological Indicator Choices 

in Stated Preference Valuation. Environmental Resource Economics. Published online, February 8, 2013.
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the Rhode Island study and the present context address policy changes that increase the 

number of forage fish in aquatic habitat with unknown effects on overall fish populations. 

The Rhode Island study was developed originally as a case study addressing Rhode 

Island residents’ preferences for the restoration of migratory fish passage over dams in 

Rhode Island’s Pawtuxet and Wood-Pawcatuck watersheds. It estimates nonuse values by 

asking respondents to consider changes in ecological indicators reflecting quantity of 

habitat, abundance of wildlife, ecological condition, and abundance of migratory fish 

species. Within this study, estimated values were based on the relative change in 

abundance of fish species most affected by restoration. 

EstimatedEstimating benefit functions from the Rhode Island choice experiment 

survey164 allows one to distinguish benefits associated with resource uses from those 

associated primarily with nonuse motives. Within the benefit transfer application, WTP is 

quantified for increases in non-harvested fish alone on the basis of the implicit price for 

migratory fish changes. This transfer holds constant all effects related to identifiable 

human uses constant (e.g., effects on catchable fish, public access, and observable 

wildlife). The remaining welfare effect—derived purely from effects on forage fish with 

 

164 Johnston, R.J. E.T. Schultz, E.T., K. Segerson, E.Y. Besedin, and M. Ramachandran. 2012. Enhancing 

the content validity of stated preference valuation: The structure and function of ecological indicators. Land 

Economics, 1: 102-120; Zhao, M., Johnson, R. J. and Schultz, E. T. 2013. What to Value and How? 

Ecological Indicator Choices in Stated Preference Valuation. Environmental Resource Economics.

Published online, February 8, 2013.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review*** 

Page 502 of 642 

little or no direct human use—may therefore be most accurately characterized as a 

nonuse benefit realized by households. 

The estimation of nonuse values involved the following steps: 

1. Use a model published by Zhao et al.165 to estimate household WTP per percent 

increase in the number of fish in a given watershed. The household WTP values 

reflect a survey variantversion that characterizes effects on the number of 

migratory fish passing upstream. 

2. Calculate the relative change in abundance for the fish species most affected by 

the regulation. The structure of the transfer study dictates that WTP should be 

evaluated based on the single species that would experience the greatest relative 

increase in abundance from restoration and that WTP estimates from multiple 

species impacted by IM&E should not be treated as strictly additive. After 

reviewing available stock assessment data, current stock size, and the magnitude 

of IM&E, EPA determined winter flounder to be the species likely to experience 

the greatest percent increase in abundance among those species with sufficient 

stock information to conduct the analysis within the boundaries of the North 

Atlantic and Mid-Atlantic benefits regions. This species is harvested; however, 

fishearly life stages of recreational and commercial species may be eaten by other 

organisms during early life-stages and therefore have nonuse values. 

 

165 Zhao, M., Johnson, R. J. and Schultz, E. T. 2013. What to Value and How? Ecological Indicator Choices 

in Stated Preference Valuation. Environmental Resource Economics.Op cit..
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3. Estimate total household WTP by applying model results for WTP per percentage 

of estimated winter flounder impingement mortality and entrainment. Total 

regional WTP is the product of household WTP and the number of households in 

the affected region (for details, see Chapter 8 of the BA). 

b. Estimated Nonuse Benefits for the North Atlantic and Mid-Atlantic Regions 

EPA expects that a decrease in impingement mortality and entrainment will lead 

to increased fish abundance in affected water bodies, thus increasing nonuse benefits. 

Exhibit X-7 shows the benefits that would result from reducing impingement mortality 

and entrainment through today’s final rule and other options considered. Application of 

the transfer study requires that the increases be expressed as a percent improvement from 

current conditions relative to a maximum number of fish that could be supported. EPA 

calculated estimates of WTP on the basis of the increase in age-1 equivalent winter 

flounder relative to the estimated number of age-1 fish when the stock is at maximum 

sustainable yield, thus assuming that the future survivalpopulation structure of age-1 

equivalents spared under the final rule will becurrent stock is similar to the larger stock. 

The total annualized nonuse benefits for the North Atlantic and Mid-Atlantic regions for 

the existing unit provision of the final rule are $1.0 million using a 3 percent discount rate 

and $0.98 million using a 7 percent discount rate. For other options considered, 

annualized nonuse benefits range from $0.3 to $52.751 million using a 3 percent discount 

rate and $0.3 to $39.937 million using a 7 percent discount rate. 
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Exhibit X-7. Annual nonuse benefits from eliminating or reducing IM&E at existing facilitiesunits at existing 

facilities in the North Atlantic and Mid-Atlantic regions for the final rule and options considered a

Regulatory option b

Winter flounder 

IM&E 

(million A1E) 

Increased winter flounder 

A1E abundance (%) 

3% discount rate 

(millions 2011$) 

7% discount rate 

(millions 2011$) 

Proposal Option 4 0.03 0.02% 0.3 0.3 

Final Rule – Existing 

Units 0.08 0.07% 1.0 0.98

Proposal Option 2 4.78 4.18% 52.751.1 39.937.3

Baseline 6.23 5.44% 10299.1 103.796.9

a

 IM&E = impingement and entrainment; A1E= age-one equivalent; 

b

 IM&E Effects by Option: Proposal Option 4 = impingement mortality limitations based on modified traveling screens for 

all facilities with flow greater than 50 mgd; Final Rule = impingement mortality limitationsstandards based on modified 

traveling screens for all facilities with flow greater than 2 mgd; Proposal Option 2 = intake flow commensurate with closedcycle cooling for facilities that have a DIF of greater than 125 mgd and impingement mortality limitations based on 

modified traveling screens for all facilities with flow greater than 2 mgd. 

 

c. Stated Preference Survey 

EPA conducted a stated preference survey to calculate benefits associated with 

minimizing adverse impacts to aquatic ecosystems from cooling water intakes. However, 

EPA is also seeking SAB input on whether and how this survey could be used, as support 

for national rulemaking or NPDES permitting whenever benefit-cost analysis is 

considered. Refer to Sections VI.F.1 and X.D.1 for additional discussion of the stated 

preference survey. EPA did not rely on the results of its stated preference survey in 

estimating the benefits of today’s rule. 
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6. Threatened and Endangered Species 

This section summarizes methods and results of EPA’s analysis of benefits from 

improved protection of T&E species from today’s final rule and options considered. 

Chapter 5 of the BA provides further detail on this analysis. 

Even if levels of mortality due to impingement and entrainment from cooling 

water intake structures of T&E species are low in absolute numbers, they may represent a 

substantial portion of annual reproduction because of the reduced population levels that 

cause a species to be protected. Consequently, impingement mortality and entrainment 

may either lengthen recovery time, or hasten the demise of these species. Adverse effects 

of cooling water intake structures on T&E species can occur in several ways: 

 Populations of T&E species may suffer direct harm as a consequence of 

impingement mortality and entrainment. 

 T&E species may suffer indirect harm if a cooling water intake structure alters 

food webs. 

 Cooling water intake structures can alter habitat designated as critical to the longterm survival of T&E species (e.g., thermal discharges associated with oncethrough cooling)..

Consequently, the 316(b) regulation will help preserve threatened and endangered 

species. 

a. Qualitative Assessment of Impingement Mortality and Entrainment Impacts on 

T&E Species 
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By definition, T&E species are characterized by low population levels. As such, it 

is unlikely that these species are recorded in significant number, if recorded at all, in 

impingement mortality and entrainment monitoring studies. Thus, losses are difficult to 

identify and quantify in a framework developed for non-listed species. Consequently, 

EPA developed a qualitative methodology to estimate the number of T&E species 

affected by impingement mortality and entrainment. 

To qualitatively assess the potential for cooling water intake structure impacts on 

aquatic T&E species, EPA constructed a database that assessed the geographical overlap 

of cooling water intake structure and habitat used by aquatic T&E species. This database 

identified the number of T&E species potentially affected by each complyingregulated

316(b) facility, and the number of facilities potentially affecting each T&E species. 

Additional details are in Chapter 5 of the BA. 

Using this database, EPA found 99 federally Federally-listed aquatic T&E species 

that overlap with at least one covered cooling water intake structure (an interaction in 

Exhibit X-8). T&E species included freshwater, marine, and anadromous fish, freshwater 

mussels, and sea turtles. On average, the habitat of each T&E species overlapped with 22 

covered facilities (Exhibit X-8), suggesting that the 316(b) rule may have substantial 

positive benefits of ensuring the long-term sustainability and recovery of T&E species. 

Exhibit X-8. Number of regulated 316(b) cooling water intake structures in aquatic T&E species habitat on a 

per-species basis

Subset of affected speciesa b Species Interactionsb Facilities per T&E speciesc

Avg Max 

All T&E Species 99 2,158 21.8 103 
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T&E Freshwater Mussels 53 1,176 21.8 103 

T&E Anadromous Fish 12 235 19.6 101 

T&E Freshwater Fish 21 65 3.1 7 

T&E Snails 7 199 28.4 49 

Sea Turtles 6 483 80.5 102 

a

 Aquatic T&E species includes species listed as threatened or endangered by the U.S. Fish and Wildlife 

Service (freshwater) or National Oceanic and Atmospheric Administration National Marine Fisheries Service 

(marine). Only aquatic species overlapping with a minimum of one cooling water intake structure are included. 

b

 Each interaction represents an overlap between the range of a T&E species and cooling water intake 

structure. 

c

 Avg = average, Max = maximum 

b. Quantitative Assessment of Impingement Mortality and Entrainment Impacts on 

T&E Species 

Although difficult to observe and quantify, EPA identified 14 T&E species with 

confirmed impingement mortality and entrainment based on facility impingement 

mortality and entrainment studies. EPA notes that some impingement mortality and 

entrainment studies identifying T&E losses were conducted prior to the listing of the 

species under the ESA and would thus not represent an illegal take under the ESA.. In 

addition to documented species-level instances of T&E mortality, EPA identified 

impingement mortality and entrainment at the level of genera166 when these genera 

contain a T&E species whose habitat range overlapped the reporting facility’s cooling 

water intake structure. Although these are not confirmed impingement mortality and 

 

166 Genera is the plural of genus. Genus is the rank superior to species in taxonomic biological 

classification. For example, the genus of Atlantic salmon (Salmo falar) is Salmo. 
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entrainment of T&E species, they provide evidence that additional T&E species are likely 

to be directly affected by impingement mortality and entrainment. EPA found seven 

genus-level matches, suggesting that the 14 T&E species suffering impingement 

mortality and entrainment may be inaccurate. 

Of the 14 federally Federally-listed T&E species for which EPA was able to 

document losses in impingement mortality and entrainment studies, EPA was able to 

quantify impingement mortality and entrainment for two species (pallid sturgeon and 

Topeka shiner). The documented impingement mortality and entrainment occurred before 

these species were Federally-listed. Data were either qualitative or of insufficient quality 

to quantify local or regional impingement mortality and entrainment for the remaining 12 

federally Federally-listed T&E species. EPA also quantified impingement mortality and 

entrainment for the American paddlefish (Polyodon spathula), listed by several states as 

threatened or endangered under stateState law, using facility impingement mortality and 

entrainment studies. Exhibit X-9 presents EPA’s estimates of baseline annual 

impingement mortality and entrainment, and reductions in impingement mortality and 

entrainment which EPA estimates will occur under the final rule and other options 

considered. 

Exhibit X-9. Baseline annual IM&E for T&E species and reductions for existing units at existing facilities 

(A1Es) a,b

Species Proposal Option 4 

Final Rule – 

Existing Units Proposal Option 2 Baseline 

Paddlefish c 8,658.97,930.1 8,987.1245.4 16,840.915,

659.

7

18,841.4 
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Pallid Sturgeon 7165.4 73.767.6 84.978.0 89.5 

Topeka Shiner 3,117.52,910.9 3,280009.8 3,780.4471

.9

3,984.9 

Total 

 

11,907.810,906.

4

12,341.711,32

2.8

20,706.219

,209.

5

22,915.7 

a

 IM&E = impingement and entrainment; A1E= age-one equivalent; 

b

 IM&E Effects by Option: Proposal Option 2 = impingement mortality limitations based on modified 

traveling screens for all facilities with flow greater than 50 mgd; Final Rule = impingement mortality 

limitationsstandards based on modified traveling screens for all facilities with flow greater than 2 mgd; 

Proposal Option 2 = intake flow commensurate with closed-cycle cooling for facilities that have a DIF of 

greater than 125 mgd and impingement mortality limitations based on modified traveling screens for all 

facilities with flow greater than 2 mgd. 

c

 The American paddlefish is not a federally Federally-listed T&E species but is listed as threatened or 

endangered on several state lists.

d

 This analysis is based solely on IM controls.

Impingement mortality and entrainment is only one of many factors that adversely 

affect T&E species. Estimating total population impacts from changes in impingement 

mortality and entrainment requires estimates of current populations of these fish and 

estimates of other anthropogenic effects which were not readily available for all T&E 

species with quantified impingement mortality and entrainment at the time of this 

analysis. Therefore, EPA was unable to quantify effects on T&E populations from the 

316(b) regulation. 

c. Valuation Methods of T&E Fish Species 

EPA had sufficient data from impingement mortality and entrainment studies to 

quantify impingement mortality and entrainment estimates for three T&E species, 

Topeka shiner, pallid sturgeon, and paddlefish (Exhibit X-9). Two of these species (pallid 
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sturgeon and paddlefish) have potential use values. A limited recreational fishery (mostly 

catch and release) exists for paddlefish in several states; although harvesting pallid 

sturgeon is illegal, the species is sometimes caught by recreational anglers. EPA 

estimated recreational use values for pallid sturgeon and paddlefish by applying transfer 

values from a Random Utility Model analysis it conducted to evaluate recreational 

fishing benefits of the 316(b) Phase II regulation to quantified impingement mortality and 

entrainment (for details, see Chapter 5 of the BA). 

EPA was unable to generate estimates of nonuse values for T&E fish species 

because reliable population estimates needed to transfer the values were unavailable. 

However, EPA emphasizes that nonuse values for T&E fish species are likely to be 

significantly greater than any use values. Harvest of these species is prohibited, reflecting 

a societal judgment that protection and preservation of these species is of greater value 

than harvest. 

d. Estimated Monetary Benefits from Reduced Mortality of T&E Fish Species 

 Exhibit X-10 presents the estimated annualized benefits for a subset of T&E 

species. For existing units under the final rule, EPA estimates total annualized use 

benefits for T&E species with quantified impingement mortality and entrainment of 

$0.54 million using a 3 percent discount rate and $0.43 million using a 7 percent discount 

rate. For other options considered, annualized benefits range from $0.4 to $0.7 million 

using a 3 percent discount rate and $0.43 to $0.5 million using a 7 percent discount rate. 
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Exhibit X-10. Annual use benefits from eliminating or reducing IM&E of T&E species at all regulatedexisting 

units of existing facilities afor the final rule and other options considereda,b,c

Regulatory option 

Increased harvest 3% discount rate 7% discount rate 

(number of fish) (million 2011$) (million 2011$) 

Proposal Option 4 8,730.37,995.5 0.4 0.43

Final Rule – Existing 

Units 

9,060.8,313.0 0.54 0.43

Proposal Option 2 16,925.815,737.7 0.7 0.5 

Baseline 18,930.9 1.2 1.23

a

 IM&E = impingement and entrainment; T&E = threatened and endangered 

Values are included for pallid sturgeon and paddlefish in the Inland region. 

b

 IM&E Effects by Option: Proposal Option 4 = impingement mortality limitations based on modified traveling 

screens for all facilities with flow greater than 50 mgd; Final Rule = impingement mortality 

limitationsstandards based on modified traveling screens for all facilities with flow greater than 2 mgd; 

Proposal Option 2 = intake flow commensurate with closed-cycle cooling for facilities that have a DIF of 

greater than 125 mgd and impingement mortality limitations based on modified traveling screens for all 

facilities with flow greater than 2 mgd.

c

 This analysis is based solely on impingement mortality controls.

EPA notes that the benefit values presented in Exhibit X-10 represent only a 

fraction of values for T&E species potentially affected by the final existing facilities rule. 

The Agency was able to obtain only use values and for only a small subset of all affected 

T&E species. Moreover, because of the nature of T&E species, even a small increase in 
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population could yield economic and ecological benefits (e.g., Richardson and Loomis167; 

Bell et al.168; Berrens et al.169) 

e. Valuation Methods for T&E Sea Turtles 

In addition to estimating values of T&E fish with quantitative estimates of 

impingement mortality and entrainment, EPA estimated the WTP for sea turtle 

conservation. In this analysis, EPA applied estimates from a study using a stated 

preference valuation approach to estimate total economic value of a management 

program that reduces the risk of extinction of loggerhead sea turtles.170

Although impingement mortality and entrainment of turtles is relatively low 

compared to mortality from shrimp trawling and other fisheries,171 it is known that 

reducing turtle mortality during juvenile and subadult life stages can have a substantial 

positive effect on population growth.172 The marginal change in extinction probability of 

sea turtles due to 316(b) regulatory options is likely to be at least 0.01, or a 1 percent 

decrease in the probability of extinction over 25 years. This assessment is based on 

 

167 Richardson, L., and J. Loomis. 2009. The total economic value of threatened, endangered and rare 

species: An updated meta-analysis. Ecological Economics, 68(5): 1535-1548. 

168 Bell, K.P, D. Huppert, and R.L. Johnson. 2003. Willingness to pay for local coho salmon enhancement 

in coastal communities. Marine Resource Economics, 18: 15-31. 

169 Berrens, R.P, P. Ganderton, and C.L. Silva. 1996. Valuing the protection of minimum instream flow in 

New Mexico. Journal of Agricultural and Resource Economics 21(2): 294-309. 

170 Whitehead, J.C. 1993. Total economic values for coastal and marine wildlife: specification, validity, and 

valuation issues. Marine Resource Economics, 8(2): 119-132. 

171 Plotkin, P. T., (Ed). 1995. National Marine Fisheries Service and U. S. Fish and Wildlife Service Status 

Reviews for Sea Turtles Listed under the Endangered Species Act of 1973. National Marine 

Fisheries Service. Silver Spring, MD. 

172 Crouse, D.T, L.B. Crowder, and H. Caswell. 1987. A stated-based population model for loggerhead sea 

turtles and implications for conservation. Ecology, 68(5): 1412-1423. 
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reports that impingement mortality and entrainment may result in the loss of more than 

100 turtles per year and because turtle population growth rates are known to be sensitive 

to changes in juvenile and subadult life stages.173

f. Benefits from Reduced Mortality of T&E Sea Turtles 

The U.S. range of loggerhead sea turtles includes the Gulf of Mexico, South 

Atlantic, Mid-Atlantic, and North Atlantic 316(b) regions.174 To calculate national WTP 

for an increased 25-year survival probability of loggerhead sea turtles, EPA assumed the 

affected population to include households in States with 316(b) facilities that are in 

loggerhead sea turtle habitat. EPA determined that 54.8 million households would be 

willing to pay for improved protection of loggerhead sea turtles. Although incidences of 

mortality have been reported at facilities in California, Texas, Florida, South Carolina, 

North Carolina, and New Jersey, EPA does not have sufficient information to quantify 

total sea turtle losses due to intakes or the reductions in such losses that might occur from 

the final rule or options considered. But as an illustrative example, assuming that the 

survival probability of loggerhead sea turtles over 25 years were increased by 1 percent, 

and applying a mean household value of $0.37 (2011 dollars), the monetized value would 

be $19.3 million and $18.8 million and $20.2 million using discount rates of 3 percent 

and 7 percent, respectively. EPA is presenting these estimates only to demonstrate the 

 

173 Ibid. 174 U.S. Fish and Wildlife Service (USFWS) (2010c). "North Florida Ecological Services Office: 

Loggerhead Sea Turtle (Caretta caretta)." Available at 

http://www.fws.gov/northflorida/seaturtles/turtle%20factsheets/loggerhead-sea-turtle.htm. 
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potential range of benefits, and is not including them in national benefits totals for the 

final rule and options considered. Actual household values and total benefits may be 

higher or lower than these estimates, with Proposal Option 2 likely to provide 

substantially greater benefits than the final rule and Proposal Option 4.

Because EPA does not currently have accurate national estimates of impingement 

mortality and entrainment for turtle species, nor are population models available that 

estimate the effect of 316(b) regulation on population size and extinction risk, these 

estimates are presented only as an illustrative example and are not included in national 

totals. 

g. Other Indications of Society’s WTP for Protection of T&E Species 

Many sources provide information that indicates that society places significant 

value on protecting T&E species. These include, but are not limited to: 

 The Endangered Species Act of 1973, which provides for the conservation of 

T&E species of fish and wildlife. Federal and State expenditures on T&E species 

waswere $593.1 million during fiscal year 2011 just on protection of those 

federally Federally-listed T&E species that have habitat overlapping cooling 

water intake structures. This accounted for 68 percent of the $869.1 million spent 

on fish, marine reptiles, crustaceans, corals, clams, aquatic snails and marine 

mammals listed under the Endangered Species Act.175

 

175 U.S. Fish and Wildlife Service. 2012. Federal and State Endangered and Threatened Species 

Expenditures. Fiscal Year 2011. 
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 Restrictions on activities in the habitat occupied by T&E species. For example, 

water diversions on the San Joaquin-Sacramento River delta, in place to protect 

the Delta Smelt (Hypomesus transpacificus), limit the extraction of water for 

drinking and agriculture. 

 The willingness of individuals to volunteer their time to conserve T&E species. 

For example, dozens of organizations recruit thousands of volunteers every year 

to participate in sea turtle conservation and research projects. Volunteers are often 

required to undergo substantial training and commit to long hours. 

While costs to replace, protect, or enhance stocks, and costs to users affected by 

efforts to conserve stocks are not direct measures of economic benefits, they indicate that 

society is willing to pay significant sums to protect and restore populations of T&E 

species. Although impingement mortality and entrainment is only one of many stressors 

on these species, reducing the amount of impingement mortality and entrainment could 

contribute to the recovery of populations over time, thereby eliminating some costs 

associated with conserving T&E species. 

7. Assessment of Thermal Discharge Impacts 

In addition to reducing total impingement mortality and entrainment, closed-cycle 

cooling reduces thermal pollution. Most retrofit installations of cooling towers at electric 

generating facilities have been required by NPDES permits to reduce thermal discharges. 

Since thermal discharges are a product of cooling water intake structures, the impacts of 

thermal discharges are a relevant considerationbenefit to consider when assessing 

appropriate technologies to reduce the effects of cooling water intakes. The installation of 
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technologies, such as closed-cycle cooling systems, can reduce thermal pollution 

significantly. Thermal pollution has long been recognized to cause harm to the structure 

and function of aquatic ecosystems. Concerns about the impacts of thermal discharges are 

addressed by State water quality standards that, when implemented through NPDES 

permits, limit the amount of heat that can be discharged to a receiving water and result, in 

some cases, in technology-based permit conditions. Section 316(a) of the CWA applies to 

point sources with thermal discharges. It authorizes the NPDES permitting authority to 

impose alternative effluent limitations for the control of the thermal component of a 

discharge in lieu of the effluent limitations that would otherwise be required under 

sections 301 or 306 of the CWA. Before such a “thermal variance” can be granted, the 

permittee must demonstrate that the alternative limit will assure the protection and 

propagation of a balanced, indigenous population of shellfish, fish and wildlife in and on 

the body of water into which the discharge is to be made. 40 CFR 125.73(a). 

EPA did not quantify nationally the impacts of thermal discharges. However, 

numerous studies have shown that thermal discharges may substantially alter the 

structure of aquatic communities by modifying photosynthetic, metabolic, and growth 

rates. Thermal discharges also harm aquatic life by reducing levels of dissolved oxygen, 

altering the location and timing of fish behavior such as spawning, aggregation, and 

migration, and may cause thermal shock-induced mortality for some species. Adverse 

temperature effects may also be more pronounced in aquatic ecosystems that are already 

subject to other environmental stressors such as high levels of biochemical oxygen 

demand, nutrient and sediment contamination, or pathogens. Within mixing zones, which 
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often extend several miles downstream from outfalls, thermal discharges may impair 

efforts to restore and protect the water bodywaterbody. For example, permit requirements 

to limit nitrogen discharges in a watershed, and thereby reduce harmful algal blooms, 

may be counteracted by thermal discharges which promote growth of harmful algae. 

Thermal discharges may have indirect effects on fish and other vertebrate populations 

through increasing pathogen growth and infection rates. 

Thermal discharges may thus alter the ecological services, and reduce the 

benefits, of aquatic ecosystems that receive heated effluent. The magnitude of thermal 

effects on ecosystem services is related to facility-specific factors, including the volume 

of the water bodywaterbody from which cooling water is withdrawn and returned, other 

heat loads, the rate of water exchange, the presence of nearby refugia, and the assemblage 

of nearby fish species. 

8. Assessment of Social Cost of Carbon 

The social cost of carbon reflects the estimated increase in the burden of global 

warming to society in future years due to higher greenhouse gas (GHG) emissions, 

measured as CO2 equivalents, associated with additional energy requirements – energy 

penalty, auxiliary energy requirements, and compliance technology installation – of 

regulatory options. EPA estimated positive or negative benefits associated with the social 

cost of carbon for changesdecreases or increases, respectively for Proposal Option 4 and 

Final Rule or Proposal Option 2, in energy requirements at complyingregulated facilities 

under the final rule and other options considered. 
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EPA’s estimates of changes in CO2 emissions were based on results from the 

IPMelectricity market analysis conducted for the proposed rule.using IPM.176 For electric 

generators, EPA estimated the change in CO2 resulting from boththe energy penalty 

associated with close-cycle recirculating technology, auxiliary energy requirement for 

operating compliance technology, and technology installation downtime. For 

manufacturers, EPA estimated the change in carbon emissions resulting only from the 

energy penalty. and auxiliary energy requirement. For compliance technology installation 

downtime at manufacturers, EPA assumed no change in carbon emissions as the shortterm replacement of energy by electric power generating facilities that would otherwise 

be produced at manufacturers could either increase or decrease emissions. 

To estimate benefits associated with the reductions in carbon emissions, EPA 

used social cost of carbon values calculated from the 20102013 document titled, 

Technical Support Document: Technical Update of the Social Cost of Carbon for 

Regulatory Impact Analysis -Under Executive Order 12866, developed by the U.S. 

Government Interagency WorkWorking Group on Social Cost of Carbon. The Agency 

used the workgroup’sWorking+ Group’s annual social cost of carbon values for 2010 

through 2050 based on the 3 percent average discount rate, which EPA has concluded is 

the most appropriate discount rate for intergenerational benefits such as the social cost of 

 

176 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. 
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carbon. See Chapter 9 of the BA for annual social cost of carbon values based on 

discount rates of 2.5, 3 (high) and 5 percent. Benefits for each year of the analysis period 

were calculated by multiplying the change CO2 emissions by the SCC value for that year. 

Similar to the treatment of other benefits, EPA discounted all year-specific social cost of 

carbon values to the beginning of 2013 and calculated an annualized value over 51 years 

using a 3-percent discount rate. EPA acknowledges that it is mixing estimates of benefits 

categories analyzed at different discount rates, but finds in this case that using different 

discount rates is justified by the intergenerational nature of the social cost of carbon, for 

purposes of the sensitivity analysis based on a 7 percent discount rate to discount other 

benefit categories. 

Exhibit X-11 presents annualized benefits for existing units for the final rule and 

options considered. Included in the monetized benefits is EPA’s estimate that the final 

rule will reduce greenhouse gas emissions by 9.3 million tons of CO2-equivalent 

emissions over the 40-year compliance period for this analysis. Both the final rule and 

Proposal Option 4 result in a net reduction in CO2 emissions for existing units during the 

analysis period. Proposal Option 2 would result in a net increase in emissions and 

negative benefits for existing units. Using a 3 percent discount rate, annualized benefits 

under the final rule for existing units are $6.412 million. Using a 7 percent discount rate, 

annualized benefits under final rule for existing units are $7.213 million. 
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Exhibit X-11. Benefits Associated with Social Cost of Carbon for Existing Units for the Final Rule and Other 

Options Considered (in millions of 2011 dollars)a

Regulatory Optionb 3 % Discount Rate 7 % Discount Rate 

Proposal Option 4 $612.4 $7.213.4

Final Rule – Existing 

Units 

$612.4 $7.213.4

Proposal Option 2 -$-1,111643.1 -$842.8-1,218.2

a

 Benefits are based on the workgroup’s average social cost of carbon values using 3 percent rate. 

9. Benefits for New Units 

In addition to the final rule and other options considered for existing units, EPA 

analyzed the benefits of the requirements for new units at existing facilities. EPA could 

not directly apply the benefits methodology used for IM&E (impingement mortality and 

entrainment) reductions at existing units to new units because it lacks facility-specific 

information to estimate regional impingement mortality and entrainment reductions for 

new units. Instead, EPA estimated benefits associated with IM&E reductions for the new 

unitsunit requirements on the basis of the monetary benefits per million gallons per day 

from the analysis of existing units. EPA also estimated benefits associated with changes 

in GHG emissions as the result of the energy penalty associated with operating cooling 

towers using the social cost of carbon. Exhibit X-12 below presents the estimates of 

monetized benefits for the new unitsunit requirements. MonetizedTotal monetized benefits 

are -$0.42 million discounted at 3 percent and -$0.1 million discounted at 7 percent. 
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Exhibit X-12. National benefits under the final rule for new units at existing facilities (in 2011 dollars) 

Regulatory 

option a

 Monetized benefit categories 

Recreational 

fishing

Commercial 

fishing Nonuse T&E speciesb

Social Cost of 

Carbonc Total 

3% discount rate (millions 2011$) 

Final Rule 

- New 

Units 

0.40 0.0 0.71 0.0 -1.50.3 -0.42

7% discount rate (millions 2011$) 

Final Rule 

- New 

Units 

$0.30 0.0 0.50 0.0 -0.92 -0.1 

a

 IM&E Effects: Final Rule – New Units - entrainment requirements for all stand-alone facilities where the turbine and 

condenser are newly built or replaced, except in the case of high energy efficiency units

b Benefits estimates for T&E species are restricted to recreational fishing benefits from increased catch of T&E species. They 

do not include benefits for reduced mortality of T&E sea turtles and other nonuse values associated with T&E species. 

c

 Benefits are based on the workgroup’sWork Group’s average social cost of carbon values using the 3 percent rate. 

10. National Monetized Benefits 

Quantifying and monetizing reductions in impingement mortality and entrainment 

attributable to the final rule and other options considered, is challenging. National benefit 

estimates are subject to uncertainties inherent in valuation approaches used to assess the 

benefits categories (see Chapters 5, 6, 7, 8, 9, and 12 of the BA). While EPA has no data 

to indicate that the results for each benefit category are atypical or unreasonable, some 

potentially significant benefit categories have not been fully monetized, and thus the 

national monetized benefits presented below likely underestimate total benefits. 

Exhibit X-13 presents EPA’s estimates of the partial monetized benefits from 

impingement mortality and entrainment reduction and the social cost of carbon for the 
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final rule and other options considered. These monetized values represent use values 

from increased commercial and recreational catch, benefits transfer of recreational 

fishing benefits of threatened and endangered species, nonuse values associated with an 

increase in fish abundance (those fish that are not caught) in the NorthNortheast and MidAtlantic benefit regions, and national benefits estimates associated with the social cost of 

carbon. For the final rule for existing and new units, partial estimated benefits from 

reducing impingement mortality and entrainment at existing units are $21.233 million 

using a 3 percent discount rate and $18.829 million using a 7 percent discount rate. EPA 

was not able to fully monetize the benefits for this proposalthe final rule. Thus, the 

estimates represent a conservative (i.e., low) estimate of total regulatory benefits of the 

final rule. 
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Exhibit X-1113. Summary of national benefits for all regulated facilities for the final rule 

Regulatory 

option a

Monetized benefit categories 

Recreational 

fishing

Commercial 

fishing Nonuse T&E Speciesb

Social Cost of 

CarbonCarbonc Total 

3% discount rate (millions 2011$) 

Final Rule 

– Existing 

Units 

12.818.2 0.9 1.0 0.54 612.4 21.633.0

Final Rule 

– New 

Units 

0.40 0.0 0.71 0.0 -1.50.3 -0.42

Final Rule 

(Existing 

Units + 

New Units) 

13.218.3 0.9 1.81 0.54 4.912.1 21.232.8

7% discount rate (millions 2011$) 

Final Rule 

– Existing 

Units 

9.813.5 0.7 0.98 0.43 7.213.4 18.928.7

Final Rule 

– New 

Units 

0.30 0.0 0.51 0.0 -0.92 -0.1 

Final Rule 

(Existing 

Units + 

New Units) 

10.113.5 0.7 1.40.9 0.43 6.313.2 18.828.6

a

 IM&E Effects: Final Rule–Existing Units = impingement mortality limitationsstandards based on modified traveling screens for 

all facilities with flow greater than 2 mgd; Final Rule–New Units: entrainment requirements for all stand-alone facilities where 

the turbine and condenser are newly built or replaced. 

b Benefits estimates for T&E species are restricted to benefit transfer of recreational fishing benefits from T&E species. They 

do not include benefits for reduced mortality of T&E sea turtles and other nonuse values associated with T&E species. 

c

 Baseline does not include potential benefits associated with the social cost of carbon. 

Exhibit X-14 presents total monetized benefits for the final rule and other options 

EPA considered for existing units by benefit category using a 3 percent discount rate. 
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Annual monetized benefits are slightly higher for the final rule than Proposal Option 4, 

and are negative for Proposal Option 2. Including both existing and new units, annual 
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monetized benefits are $32.8 million for the final rule, $30.8 million for Proposal Option 

4 and -$1,542.8 million for Proposal Option 2.

Exhibit X-14. Summary of national benefits for all regulated facilities for the final rule and other 

 options EPA considered (3% discount rate) 

Monetized Benefit 

Categories 

Annual Benefits by Regulatory Optiona 

(millions 2011$)

Proposal Option 4 Final Rule – Existing Units Proposal Option 2 

Existing Units 

Recreational 

Fishing 

17.1 18.2 43.0 

Commercial 

Fishing 

0.9 0.9 3.9 

Nonuse 0.3 1.0 51.1 

T&E Speciesb 0.4 0.4 0.7 

Social Cost of 

Carbon 

12.4 12.4 -1,641.3 

Total 31.0 33.0 -1,542.6 

Final Rule - New Units 

Total -0.2 -0.2 -0.2 

Existing and New Units 

Total 30.8 32.8 -1,542.8 

a

 IM&E Effects: Proposal Option 4 = impingement mortality limitations based on modified traveling screens for all 

facilities with flow greater than 50 mgd; Final Rule–Existing Units = impingement mortality limitations based on 

modified traveling screens for all facilities with flow greater than 2 mgd; Proposal Option 2 = impingement mortality 

limitations based on modified traveling screens for all facilities with flow greater than 2 mgd and entrainment mortality 

limitations commensurate with closed-cycle recirculating systems for all facilities with flow greater than 125 DIF; Final 

Rule–New Units: entrainment requirements for all stand-alone facilities. 

b Benefits estimates for T&E species are restricted to benefit transfer of recreational fishing benefits from T&E 

species. They do not include benefits for reduced mortality of T&E sea turtles and other nonuse values associated 

with T&E species.
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EPA recognizes that its estimates of ecological and economic benefits projected to occur 

under regulation are affected by uncertainty at many levels. 

 Not all ecological goods and services affected by cooling water intake 

structurestructures at complyingregulated 316(b) facilities are modeled or 

monetized, suggesting that the total benefits of regulation may be underestimated. 

For example, potential increases in ecosystem stability that might occur as a result 

of regulation is not explicitly estimated nor monetized. 

 When particular ecological goods and services are monetized, data is not always 

available at the national level. For example, EPA was only able to estimate the 

nonuse benefits of impingement mortality and entrainment reductionstransfer for 

onea species within the North and Mid-Atlantic regions only, suggesting that 

nonuse values are significantly underestimatedrepresents less than one percent of 

adverse environmental impacts. 

 For the proposed rule, EPA used a habitat-based method to assess potential WTP 

for reducing fish mortality at CWIS based on the approximate area of habitat 

required to produce and support the number of organisms lost to impingement 

mortality and entrainment.177 EPA did not consider the habitat-based approach 

appropriate for primary analysis of benefits for the proposed rule, and did not 

include it in its analysis for the final rule. However, itsthe results for the proposed 

 

177 U.S. EPA. 2011. Environmental and Economic Benefits Analysis for the Proposed Section 316(b) 

Existing Facilities Rule. 
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rule illustrate that total benefits may be substantially greater than benefits 

estimated using the methodologies described in Section D. 

Because EPA was able to only partially monetize nonuse benefits using the 

benefits transfer approach, EPA expects that the actual benefits will be greater than those 

presented here. 

XI. Related Acts of Congress, Executive Orders, and Agency Initiatives 

A. Executive Order 12866: Regulatory Planning and Review and Executive 

Order 13563: Improving Regulation and Regulatory Review 

Under section 3(f)(1) of E.O. 12866 (58 FR 51735, October 4, 1993), this action 

is an economically significant regulatory action because it is likely to have an annual 

effect of $100 million or more on the economy. Accordingly, EPA submitted this action 

to the Office of Management and Budget for review under E.O. 12866 and 13563 (76 FR 

3821, January 21, 2011), and any changes made in response to Office of Management 

and Budget recommendations have been documented in the docket for this action. 

In addition, EPA prepared an analysis of the costs and benefits associated with 

this action; this analysis is discussed in detail in the Chapter 98 of the EA. A copy of itthe 

EA is available in the docket for this action, and the analysis is briefly summarized here. 
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Exhibit XI-1 (drawn from Table 9-1Chapter 8 of the EA) provides the results of 

the benefit-cost analysis.178 Placeholders for option-specific nonmonetizednon-monetized

benefits are represented by BP4 for Proposal Option 4, BFR for the final rule, and BP2 for 

Proposal Option 2. While preliminary, and not yet reviewed by EPA’s Science Advisory 

Board, the preliminary results of EPA’s stated preference survey (see BA, Chapter 11) 

suggest that BP4, BFR, and BP2 have the potential to be significantly different from zero. 

EPA is therefore using placeholders for additional benefits that are not captured by its 

analysis of use benefits and the benefits transfer for nonuse benefits. However, EPA did 

not rely on the results of its stated preference survey in estimating the benefits of today’s 

rule. EPA has concluded that the benefits of the rule justify the costs. 

EPA also analyzed the employment effects of the final rule and other options 

considered in development of this rule. The results of that analysis are summarized in 

Section XIX.E of this preamble and EA Chapter 109 of the EA. 

Exhibit XI-1. Annualized benefits and costs of the regulatory options (in millions, 2011 dollars)a

Option Total social costsb Benefitsc 

Proposal Option 4 $261.7251.8 $20.231.0 + BP4

Final Rule – Existing and New Units $297.4274.9 $21.232.8 + BFR

Proposal Option 2 $3,999.7643.2 -$1,016.5 542.6+ BP2

 

178 The costs and benefits presented in this section assume that facilities with impoundments will qualify as 

having closed-cycle recirculating systems in the baseline EPA also conducted the costs and impacts 

analysis where impoundments were not assumed to meet the definition of closed-cycle recirculating. EPA 

did not find that this assumption would change EPA’s final rule decision; see DCN 12-2501. 
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a

 Social costs and benefits were annualized over 51 years and discounted using 3 percent rate. 

b

Totalb Total social costs include compliance costs to facilities and government administrative costs. See EA Chapter 87. 

C Benefits include social cost of carbon from changes in greenhouse gas emissions due to the final rule. 

B. Paperwork Reduction Act 

The information collection requirements in this rule have beenwill be submitted 

for approval to the Office of Management and Budget (OMB) under the Paperwork 

Reduction Act, 44 U.S.C. 3501 et seq. The supporting statement in EPA’s information 

collection request estimates the burden to permitted facilities; burden is defined at 5 CFR 

1320.3(b). The 60-day comment period will be concurrent withcommence after

publication of the final ruledraft ICR. The information collection requirements are not 

enforceable until they are approved by OMB approves them.

Today's rule requires several distinct types of information collection as part of the 

NPDES permit application. In general, the information will be used to assist EPA in 

regulating environmental impacts, namely impingement mortality and entrainment, at 

cooling water intake structures and to identify how a 316(b)cooling water intake structure 

at an existing facility or a new unit at an existing facility will meet the impingement 

mortality and entrainment requirements. Today’s rule also requires other reporting and 

recordkeeping requirements to demonstrate and document compliance with the 

requirements. Compliance with the applicable information collection requirements 

established under this final rule is mandatory (see §§ 122.21(r), 125.136, 125.137, 125, 

and 138). 
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EPA does not consider the specific data that will be collected under this final rule 

to be confidential business information. However, if a respondent does consider this 

information to be confidential, the respondent may request that such information be 

treated as confidential. All confidential data submitted to EPA will be handled in 

accordance with 40 CFR 122.7, 40 CFR part 2, and EPA’s Security Manual Part III, 

Chapter 9, dated August 9, 1976. 

This final rule modifies regulations at § 122.21 to require each existing 

facilitiesfacility and new unitsunit at an existing facilitiesfacility to prepare and submit 

information as part of itsthe facility’s NPDES permit application. A detailed list of 

required data items is provided below. 

The total EPA estimates an average annual average burden for facilities of 

the634,596 hours for the final rule’s information collection requirements associated with 

the existing and new units provisions of the final rule, is estimated at 725,379 hours for 

an average of 1,289 facilities during the first three years after promulgation of the rule.179

Hence, the. Of this total, EPA estimates that 1,068 regulated facilities will incur an

annual average reporting and recordkeeping burden of 588 hours per respondent (for a 

total of 627,666 burden hours). EPA estimates that Directors in 46 States and one 

territory with NPDES permitting authority, will incur an annual average burden for the 

 

179The 1,289 figure differs from the total regulated universe of 1,065 facilities and reflects different 

numbers of generators and manufacturers undertaking activities related to information collection request 

(ICR) in each of the three years covered by this ICR. 
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collection review, oversight, and administration of the rule, of information from facilities 

complying with the final rule is estimated6,930 hours, or an annual average of 147 hours 

per permitting authority. Slight differences in calculations are due to be 543 hours per 

respondentrounding. 

The corresponding estimatesestimate of costs other than labor (labor and nonlabor costs are included in the total cost of the final rule discussed in Section IX of this 

preamble) during the first three years after promulgation of the rule is an annual average 

of $9.38.5 million. Non-labor costs include activities such as capital costs for sampling 

equipment, remote monitoring devices, laboratory services, photocopying, and the 

purchase of supplies. The burden and costs are for the information collection, reporting, 

and recordkeeping requirements for the three-year period beginning with the assumed 

effective date of this rule. Additional information collection requirements will occur after 

this initial three-year period as (1) existing facilities will continue to gather and submit 

required permit application materials and (2) new units at existing facilities commence 

operations and are issued permits. This burden will be counted in a subsequent 

information collection request.

Information and studies to be submitted under this final rule (as required by §§ 

122.21(r) and 125.95) by existing facilities and new units at existing facilities are listed 

below. For more information, see sectionSection VIII in the preamble. 

 Source Water Physical Data (§ 122.21(r)(2)) 

 Cooling Water Intake Structure Data (§ 122.21(r)(3)) 
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 Source Water Baseline Biological Characterization Data (§ 122.21(r)(4)) 

 Cooling Water System Data (§ 122.21(r)(5)) 

 Chosen Method of Compliance with Impingement Mortality Standards (§ 

122.21(r)(6)) 

 Performance Studies (§ 122.21(r)(7)) 

 Operational Status (§ 122.21(r)(8)) 

 Entrainment Characterization Study (§ 122.21(r)(9)) 

 Comprehensive Technical Feasibility and Cost Evaluation Study (§ 122.21(r)(10)) 

 Benefits Valuation Study (§ 122.21(r)(11)) 180

 Non-Water Quality and Other Environmental Impacts Study (§ 122.21(r)(12))

In addition to the information requirements of the permit application, NPDES 

permits normally specify monitoring and reporting requirements to be met by the 

permitted entity. Existing facilities and new units at existing facilities are required to 

perform monitoring as determined by the requirements in § 125.94 and in accordance 

with §§ 125.96 and 125.97. 

Finally, in accordance with § 125.95(e), facilities arerequiredare required to 

maintain records of all submissions that are part of its permit application for a minimum 

of five years. If the Director approves a request for reduced permit application studies 

 

180 This study may be waived by the director. 
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under § 125.95(a) or § 125.98(g), the facility must keep records of all submissions that 

are part of a previous permit application for an additional five years. Also, facilities must 

keep record of all submissions that are part of the permit reporting requirements for a 

periods of at least five years from the date of permit issuance, in accordance with § 

125.97(d). 

Burden is defined at 5 CFR 1320.3(b). 

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 

addition, EPA is amending the table in 40 CFR part 9 of currently approved OMB control 

numbers for various regulations to list the regulatory citations for the information 

requirements contained in this final rule.

C. Regulatory Flexibility Act (RFA) 

The Regulatory Flexibility Act generally requires an agency to prepare a 

regulatory flexibility analysis of any rule subject to notice and comment rulemaking 

requirements under the Administrative Procedure Act or any other statute unless the 

agency certifies that the rule will not have a significant economic impact on a substantial 

number of small entities. Small entities include small businesses, small organizations, and 

small governmental jurisdictions. 
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1. Definition of Small Entities and Estimation of the Number of Small Entities 

Subject to Today’s Final Regulation 

For EPA’s assessment of the impact of today’s final rule on small entities, small 

entity is defined as either a (1) a small business as defined by SBA (Small Business 

Administration) regulations at 13 CFR 121.201; (2) a small governmental jurisdiction 

that is a government of a city, county, town, school district, or special district with a 

population of fewer than 50,000; or (3) a small organization that is any not-for-profit 

enterprise that is independently owned and operated and is not dominant in its field. 

Federal or State entities owning regulated facilities are not small entities. 

EPA performed this assessment separately for the two classes of facilities and 

their owner entities—electric generators and manufacturers—that are subject to today’s 

rule. 

a. Electric Generators 

EPA followed the SBA criteria for identifying small, non-government entities in 

the electric power industry, as follows: 

 For non-government entities with electric power generation as a primary 

business, small entities are those with total annual electric output less than 

4 million MWh;were designated using employment size thresholds 

specific to each 6-digit NAICS code. 

 For government entities other than federalFederal or State governments, 

small entities are those with a population of fewer than 50,000. 
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 For entities with a primary business other than electric power generation, 

the relevant size criteria are based on revenue or number of employees by 

NAICS sector (see Exhibit XI-2). 

Exhibit XI-2. NAICS codes and SBA entity size standards for entities that own electric generators with a 

primary business other than electric power generation 

NAICS code NAICS description SBA size standard 

212111 Bituminous Coal and Lignite Surface Mining 500 employees 

221210 Natural Gas Distribution 500 employees 

331110 Iron and Steel Mills and Ferroalloy 

Manufacturing 

1,000 employees 

331315 Aluminum Sheet, Plate, and Foil 

Manufacturing 

750 employees 

333611 Turbine and Turbine Generator Set Units 

Manufacturing 

1,000 employees 

488320 Marine Cargo Handling $35.5 million in revenue 

491110 Postal Service $7 million in revenue 

522110 Commercial Banking $175 million in assets 

523910 Miscellaneous Intermediation $7 million in revenue 

524126 Direct Property and Casualty Insurance 

Carriers 1,500 employees 

525910 Open-End Investment Funds $7 million in revenue 

525990 Other Financial Vehicles $7 million in revenue 

541990 All Other Professional, Scientific, and 

Technical Services $14 million in revenue 

551112 Offices of Other Holding Companies $7 million in revenue 

562212 Solid Waste Landfill $35.5 million in revenue 

562219 Other Nonhazardous Waste Treatment and 

Disposal 

$35.5 million in revenue 

562920 Materials Recovery Facilities $19 million in revenue 
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611310 Colleges, Universities, and Professional 

Schools $25.5 million in revenue 

EPA conducted this analysis for the same set of parent entities it analyzed in the 

general entity-level cost-to-revenue analysis discussed in Section IX.D. To determine 

whether these are small entities on the basis of the size criteria outlined above, EPA 

compared the relevant measure for the identified parent entities to the appropriate SBA 

size criterion. EPA conducted this analysis using (1) facility-level weights without using 

entity-level weights, and (2) entity-level weights without using facility-level weights (for 

information on these two weighting approaches, see Appendix H of the EA). 

EPA estimates that between 2031 and 3952 small entities own regulated facilities, 

representingelectric generators that are subject to the rule. They represent approximately 

25 to 32 percent of all entities that own electric generators (see Exhibit XI-3). 

Exhibit XI-3. Number of small entities that own electric generators, by ownership type

Ownership typea

Using facility-level weights Using entity-level weightsweightsb

Total Small % Small Total Small % Small 

Cooperative 13 111 31.884.6

% 2221 718 31.885.7% 

Federal 1 0 0.0% 1 0 0.0% 

Investor-owned 57 86 14.310.5

% 6360 97 14.311.7% 

Municipality 1519 7 48.636.8

% 3738 1819 48.650.0% 

Nonutility 2326 47 18.526.9

% 2730 58 18.526.7% 

Other Political Subdivision 4 0 16.70.0% 6 0 0.0% 

State 3 0 0.0% 3 0 0.0% 

All Entity Types 116123 2031 25.2% 159 3952 24.532.7% 
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a State and federalFederal entities are considered large.

b In addition to the 52 small parent entities on an unweighted basis, one additional entity is an “other political subdivision 

entity” for a total of 53. This entity owns only implicitly analyzed facilities; consequently, there is no explicitly analyzed entity 

in the other political subdivision ownership category to represent this implicitly analyzed small parent entity. As the result,

weighted entity counts do not include one small other political subdivision entity.

b. Manufacturers 

EPA also used the SBA criteria for identifying small, non-government entities in 

the manufacturing sector. Exhibit XI-4 lists the SBA size threshold guidelines for entities 

that own manufacturers. 

Exhibit XI-4. NAICS codes and SBA entity size standards for entities that own manufacturers 
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NAICS code NAICS description SBA size standard 

111930 Sugarcane Farming $0.75million75 million in revenue 

113110 Timber Tract Operations $7 million in revenue 

211111 Crude Petroleum and Natural Gas Extraction 500 employees 

212210 Iron Ore Mining 500 employees 

212391 Potash, Soda, and Borate Mineral Mining 500 employees 

221122 Electric Power Distribution 4,000,000 MWh of electric generation 

311221 Wet Corn Milling 750 employees 

311314 Cane Sugar Manufacturing 750 employees 

311313 Beet Sugar Manufacturing 750 employees 

311942 Spice and Extract Manufacturing 500 employees 

313210 Broadwoven Fabric Mills 1,000 employees 

321113 Sawmills 500 employees 

322121 Paper (except Newsprint) Mills 750 employees 

322122 Newsprint Mills 750 employees 

322130 Paperboard Mills 750 employees 

322211 Corrugated and Solid Fiber Box Manufacturing 500 employees 

322220 

Paper Bag and Coated and Treated Paper 

Manufacturing 500 employees 

322291 Sanitary Paper Product Manufacturing 500 employees 

324110 Petroleum Refineries 1,500 employees 

324191 Petroleum Lubricating Oil and Grease Manufacturing 500 employees 

325120 Industrial Gas Manufacturing 1,000 employees 

325180 Other Basic Inorganic Chemical Manufacturing 1,000 employees 

325199 All Other Basic Organic Chemical Manufacturing 1,000 employees 

325211 Plastics Material and Resin Manufacturing 750 employees 

325311 Nitrogenous Fertilizer Manufacturing 1,000 employees 
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325320 

Pesticide and Other Agricultural Chemical 

Manufacturing 500 employees 

325412 Pharmaceutical Preparation Manufacturing 750 employees 

325510 Paint and Coating Manufacturing 500 employees 

325992 

Photographic Film, Paper, Plate and Chemical 

Manufacturing 500 employees 

325998 

All Other Miscellaneous Chemical Product and 

Preparation Manufacturing 500 employees 

331110 Iron and Steel Mills and Ferroalloy Manufacturing 1,000 employees 

331210 

Iron and Steel Pipe and Tube Manufacturing from 

Purchased Steel 1,000 employees 

331221 Rolled Steel Shape Manufacturing 1,000 employees 

331222 Steel Wire Drawing 1,000 employees 

331313 Alumina Refining and Primary Aluminum Production 1,000 employees 

331315 Aluminum Sheet, Plate and Foil Manufacturing 750 employees 

331410 Nonferrous Metal (except Aluminum) Smelting and 

Refining 

1,000 employees 

332312 Fabricated Structural Metal Manufacturing 500 employees 

337910 Mattress Manufacturing 500 employees 

339999 All Other Miscellaneous Manufacturing 500 employees 

423310 

Lumber, Plywood, Millwork, and Wood Panel 

Merchant Wholesalers 100 employees 

423930 Recyclable Material Merchant Wholesalers 100 employees 

424510 Grain and Field Bean Merchant Wholesalers 100 employees 

424690 

Other Chemical and Allied Products Merchant 

Wholesalers 100 employees 

424710 Petroleum Bulk Stations and Terminals 100 employees 

447190 Other Gasoline Stations $14 million in revenue 

522220 Sales Financing $7 million in revenue 

523910 Miscellaneous Intermediation $7 million in revenue 
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523930 Investment Advice $7 million in revenue 

524126 Direct Property and Casualty Insurance Carriers 1,500 employees 

525990 Other Financial Vehicles $7 million in revenue 

531110 Lessors of Residential Buildings and Dwellings $25 million in revenue 

551112 Offices of Other Holding Companies $7 million in revenue 

561110 Office Administrative Services $7 million in revenue 

Similar to the analysis conducted for electric generators, EPA conducted this 

analysis for the same set of parent entities as analyzed in the general, entity-level, cost-torevenue analysis discussed in Section IX.D. To determine which entities are small, EPA 

compared the relevant measure for the identified parent entities to the appropriate SBA 

size criterion. EPA used two sample-weighting schemes in this analysis; these provide a 

range of counts of small entities that own regulated facilities and the number of regulated 

facilities that they own. that will incur costs under the final rule. EPA does not assessfind

either of these sample-weighting schemes to be superior to the other in the quality of the 

resulting estimates of small entity counts and occurrence of impacts. The different 

weighting approaches reflect the fact that EPA used sample facilities for the impact 

analysis and lacks precise information on the profile of ownership of the total population

of regulated manufacturers facilities – in terms of the number of small entities owning 

regulated facilities and the number of regulated facilities that any small entity would own. 

EPA developed the weighting schemes using alternative bounding assumptions about the 

profile of ownership of regulated facilities by small entities. The weighting schemes 

provide lower and upper bound estimates of the numbers of small entities, and the 
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numbers of regulated facilities that they own, and accordingly, the number of small 

entities in each of the cost-to-revenue impact categories (for information on the weighting 

schemes, see Appendix H of the EA). 

From this analysis, EPA estimates that 17 to 52 small entities own regulated 

facilities in the six primary manufacturing industriesPrimary Manufacturing Industries, 

representing approximately 16 percent of all entities that own regulated facilities in these 

industries (see Exhibit XI-5).The presence of small entities varies by industry sector. 

Exhibit XI-5. Number of small entities that own regulated facilities, by industry 

Industry 

Lower-bound estimate of number of 

entities that own regulated facilities 

Upper-bound estimate of number of 

entities that own regulated facilities 

Total Small % Small Total Small % Small 

Aluminum 4 2 50.0% 11 4 40.6% 

Chemicals and Allied Products 30 5 16.7% 121 21 17.7% 

Food and Kindred Products 6 0 0.0% 20 0 0.0% 

Paper and Allied Products 37 7 18.9% 104 23 21.8% 

Petroleum Refining 16 2 12.5% 25 2 8.4% 

 

Steel 13 1 7.7% 32 2 5.2% 

Multiple Industriesa 4 0 0.0% 14 0 0.0% 

Primary Manufacturing 

IndustriesIndustriesb

 – Total 110 17 15.5% 327 52 16.0% 

a These are small entities that own regulated facilities from multiple industries. 

b EPA was unable to extend from the survey responses to estimate the total number of small entities owning regulated 

facilities in the Other Industries. Therefore, for the Other Industries, EPA reports small entity information only for the 

facilities and their owning entities as reflected in survey responses – this information involves no sample-weighting. As a 

result, the table reports the same number of small entities for Other Industries under each weighting approach. See EA 

Appendix H for more details. 

cb EPA did not compile comparable information for Other Industries facilities and the entities that own them because it did 

not have a statistically valid sample of facilities from which to develop such estimates. 

c. Total Number of Small Entities that Own Regulated Facilities 
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EPA estimates that between 3748 and 91104 small entities own regulated 

facilities in the electric power industry and six primary manufacturing industries together. 

2. Statement of Basis 

As described above, EPA began the small entity impact assessment by first 

estimating the number of small entities in the two industry segments subject to the final 

rule: electric generators and manufacturers. EPA next assessed whether these small 

entities would be expected to incur costs that constitute a significant impact and, finally, 

assessed whether those entities represent a substantial number of small entities. 

EPA summed annualized after-tax compliance costs for regulated facilities that 

are estimatedassumed to be owned by a given small entity and calculated the costs as a 

percentage of entity revenue (cost-to-revenue test). EPA compared the resulting 

percentages to impact criteria of 1 and 3 percent of revenue. EPA assumed that small 

entities estimated to incur costs below 1 percent of revenue will not face significant 

economic impacts, while small entities with costs of at least 1 percent of revenue have a 

chance of facing economic impacts, and. EPA assumed that entities incurring costs of at 

least 3 percent of revenue have a higher likelihood of significant economic impacts. 

For both electric generators and manufacturers, EPA used sample-weighting 

approaches that provide a range of estimates of the numbers of small entities and 

regulated facilities that they own.

Exhibit XI-6 summarizes the Regulatory Flexibility Act analysis results under 

both weighting approaches. for each regulated facilities segment. Overall, the RFA 

analysis for electric generators found that fewno small entities would potentially incur a 
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significant impact under the final rule. Specifically, for electric generators, EPA estimates 

that zero to three small entities will incur costs exceeding 1 percent of revenue, while no 

small entity will incur costs exceeding 3 percent of revenue. Following EPA’s guidance 

on conducting RFA analyses, the number of small entities above the threshold as a 

percent of all small entities subject to the rule are zero to 10 percent at the 1 percent of 

revenue threshold, and zero percent at the 3 percent of revenue threshold. 

The findings for manufacturers are comparable. Specifically, EPA estimates that 

three to four small parent entities will incur costs exceeding 1 percent of revenue, and 

zero to one small parent entity will incur costs exceeding 3 percent of revenue. The 

associated percentages of small entities subject to the final rule are 8 percent to 18 

percent at the 1 percent threshold, and zero percent to 6 percent at the 3 percent threshold. 

 Combining the electric generators and manufacturers segments, EPA estimates 

that three to seven small entities will incur costs exceeding 1 percent of revenue, while 

zero to one small entity will incur costs exceeding 3 percent of revenue. Following EPA’s 

guidance on conducting RFA analyses, the associatedThe corresponding percentages of 

small entities above the threshold as a percent of all small entities subjectare 4 to the rule 

are 18 to 2013 percent at the 1 percent of revenue threshold, and zero to 52 percent at the 

3 percent of revenue threshold. 

The findings for manufacturers are comparable, with very few small entities 

estimated to incur a significant impact under the final rule. Specifically, EPA estimates 

that four to five small parent entities will incur costs exceeding 1 percent of revenue, and 

zero to one small parent entity will incur costs exceeding 3 percent of revenue. The 
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associated percentages of small entities subject to the final rule are 10 percent to 22 

percent at the 1 percent threshold, and zero percent to 6 percent at the 3 percent threshold. 

 Combining the electric generators and manufacturers segments, EPA estimates 

that seven to11 small entities will incur costs exceeding 1 percent of revenue, while zero 

to two small entities incur costs exceeding 3 percent of revenue. The corresponding 

percentages of small entities are 11 to 19 percent at the 1 percent threshold, and zero to 5 

percent at the 3 percent threshold. Based on EPA guidance for RFA analyses, EPA judges 

these composite findings to provide a basis for SISNOSE determinations. 

In summary, under the final rule, EPA estimates that a small number of small 

parent entities will incur a potentially significant cost impact in the individual regulated 

industry segments, and overall, for both segments. The maximum number of small 

entities estimated to incur costs exceeding 1 percent is 11seven, overall, with seventhree

of these small entities in the electric generators segment and four in the manufacturers 

segment. The maximum number of small entities with costs exceeding 3 percent is 

twoone, overall, with oneno small entityentities in each of the electric generators segment 

and one small entity in the manufacturers segments. In each case, the maximum value 

reflects the high end of an uncertainty range that is based on different sample weighting 

approaches. EPA judges that values in the interior of these ranges represent more 

reasonable estimates of the number of small entities incurring significant impacts. The 

estimated numbers of entities with significant impacts also represent small percentages of 

the estimated number of small entities, overall, and in the individual segments. The 

maximum percentage values at the 1 percent of revenue threshold are 1913 percent, 
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overall, 2010 percent for electric generators, and 18 percent for manufacturers. At the 3 

percent threshold, the maximum percentage values are 52 percent, overall, 5zero percent 

for electric generators, and 6 percent for manufacturers. Again, these values reflect the 

high end of an uncertainty range. 

 In view of these very modest impacts, EPA judges that the final rule is not 

consequential in terms of potential impacts for small entities. 

Exhibit XI-6. Estimated cost-to-revenue impact for small entities that own facilities subject to the regulation 

Regulatory optionRegulated Segment

Cost impact category 

Cost ≥1% of revenuea Cost ≥3% of revenuea

Number of 

small entities 

% of small regulated

entitiesb

Number of 

small entitiesc

% of small regulated

entitiesb

Electric Generators 40 to 

73

180% 

to 2010% 

0 to 1 0% to 

5%

Manufacturersd 3 to 4 8% to 

18% 

0 to 1 0% to 

6% 

Electric Generators and Manufacturersd 3 to 7

to11

114% 

to 1913% 

0 to 

21

0% to 

52% 

a

 For both electric generators and manufacturers, EPA used sample-weighting approaches that provide a range of estimates 

of the numbers of small entities and regulated facilities they own (see Section VII(D)(a)(iv) for manufactures and see Section 

VII(D)(b)(1)(b) for electric generator weighting approaches). 

b

Percentageb Percentage of small entities incurring a cost-to-revenue impact involves range estimates in both the numerator 

(number of affected entities) and denominator (number of regulated entities).

c

Entitiesc Entities with cost-to-revenue ratios of at least 3 percent are included in the number of entities with cost-to-revenue 

such ratios of at least 1 percent. 

d

Entityd Entity counts used in these calculations exclude manufacturers in other industries. EPA estimated that one small 

parent entity that owns regulated facilities in other industries would incur costs exceeding 1 percent of revenue. 

3. Certification Statement 

Given these findings of very small absolute numbers of small entities estimated to 

incur significant impacts under the final rule, and low percentages of estimated small 

entities incurring impacts, EPA concludedI certify that the final rule will not have “a 
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significant impact on a substantial number of small entities” (no SISNOSE), overall and 

by individual industry segment. 

D. Unfunded Mandates Reform Act (UMRA) 

Title II of the Unfunded Mandates Reform Act of 1995, 2 U.S.C. 1531-1538, 

requires federalFederal agencies, unless otherwise prohibited by law, to assess the effects 

of their regulatory actions on State, local, and Tribal governments and the private sector. 

Today’s rule contains a federalFederal mandate that may result in expenditures of $100 

million or more forby State, local, and Tribal governments, in the aggregate, or the 

private sector, of $100 million or more (adjusted annually for inflation) in any one year. 

Accordingly, under Unfunded Mandates Reform Act section 202, EPA has prepared a 

written statement, which follows below (see Chapter 1211 of the EA). 

1. Summary of Written Statement 

a. Authorizing Legislation 

Today’s rule is issued under the authority of CWA sections 101, 301, 304, 306, 

308, 316, 401, 402, 501, and 510, (33 U.S.C. 1251, 1311, 1314, 1316, 1318, 1326, 1341, 

1342, 1361, and 1370). For detailed information on the legal authority of this rule, see 

Section III of this preamble. 

b. Benefit-Cost Analysis 

As described above, the costs, benefits and economic impacts reported in this 

section may be underestimated due to EPA’s assumption that facilities with 

impoundments will qualify as having closed-cycle recirculating systems in the baseline 

and thus, unless additional controls are required to protect listed species, will incur no 
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technology-related costs. Likewise, for this analysis, because these facilities are assumed 

not to install compliance technology, EPA also assumed they would achieve no benefits. 

Accordingly, the benefits reported in this section may be underestimated, based on the 

assumption of no technology installation for facilities with impoundments.181 The 

existing and new unitsunit provisions of today’s rule are expected to have total 

annualized pre-tax (social) costs of $297.4274.9 million. These costs include direct costs 

incurred by facilities and implementation costs incurred by federalFederal, State, and 

local governments. The total monetized use and nonuse benefits of the final rule, 

accounting for the existing and new unitsunit provisions, are estimated to be $37.232.8

million.182 Thus, the total social costs exceed the total monetized benefits of the final rule 

by $260.2 million for the final rule. EPA notes that these differences are based on a 

comparison of a partial measure of benefits with a more complete measure of costs; 

therefore, the results must be interpreted with caution. For a more detailed comparison of 

the costs and benefits of the final rule, see Chapter 98 of the EA. 

EPA notes that States may be able to use existing sources of financial assistance 

to revise and implement today’s rule. CWA section 106 authorizes EPA to award grants 

to States, Tribes, intertribal consortia, and interstate agencies for administering programs 

 

181 This factor in potential underestimation of benefits is separate from other considerations that likely lead 

to benefits underestimation, as described in this section and in the EA and BA reports. 

182 Both cost and benefit values were annualized over 51 years and discounted at 3 percent. Values include 

costs and benefits estimated for new units. EPA was able to estimategenerated partial estimates of nonuse 

benefits only for one resource changes for a species in two coastal benefit regionsthat represents less than 

one percent of adverse environmental impacts s. 
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for the prevention, reduction, and elimination of water pollution. These grants may be 

used for various activities to develop and carry out a water pollution control program, 

including permitting, monitoring, and enforcement. Thus, State and Tribal NPDES permit 

programs represent one type of State program that can be funded by CWA section 106 

grants. 

c. Summary of State, Local, and Tribal Government Input 

EPA consulted with State governments and representatives of local governments 

in developing the rule. The outreach activities are discussed in XXX.The outreach 

activities are discussed in Section III.A.3 of the preamble to the proposed rule (see 76 FR 

22268, April 20, 2011) and Chapter 2 of the TDD. EPA has also conducted additional 

outreach since the proposed rule, including several conference calls with the Association 

of Clean Water Administrators (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, which shares many of the same affected 

facilities 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. EPA also attended conferences and participated in workgroups (such as 

NARUC’s 2013 Winter Committee Meetings) where additional information about State 
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and local government interests were presented. Historically, EPA has also conducted a 

great deal of outreach in developing the previous 316(b) regulations over the past decade; 

for example, see the Phase I final preamble (66 FR 65331, December 18, 2001), the 

Phase II final preamble (69 FR 41677, July 9, 2004), and the Phase III final preamble (71 

FR 35037, June 16, 2006).

d. Regulatory Option Selected 

EPA considered and analyzed several regulatory options to determine the best 

technology available for minimizing adverse environmental impact. These regulatory 

options are discussed in Section VI of this preamble. These options included a range of 

technology-based approaches including, from impingement mortality technology at all 

facilities with a DIF of greater than 50 mgd, to additionally requiring additional

impingement mortality controls and intake flow commensurate with closed-cycle cooling 

for all facilities. As discussed in detail in Section VI, EPA did not select options 

exclusively because they are the most cost-effective among the options that fulfill the 

requirements of section 316(b). EPA selected the final rule because it meets the 

requirement of CWA section 316(b) that the location, design, construction, and capacity 

of cooling water intake structures reflect the best technology available for minimizing 

adverse environmental impacts. In addition, EPA has determined that the benefits of the 

final rule justify the costs, taking into account quantified and qualitative benefits and 

costs. The final rule reflectsEPA selected a flexible approach for the final rule from

among the options considered; it allows consideration of costs and benefits on a site-
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specific basis in determining BTA for reducing entrainment and has flexible requirements 

for reducing impingement mortality. 

2. Impact of Compliance Requirements on Small Governments 

This rule is not subject to Unfunded Mandates Reform Act section 203 

requirements because it contains no regulatory requirements that could significantly or 

uniquely affect small governments (i.e., governments with a population of fewer than 

50,000). For its assessment of the impact of compliance requirements on small 

governments, EPA compared the estimated total costs and costs per facility that small 

governments would incur with the costs that large governments would incur. EPA also 

compared costs for regulated facilities owned by small-government entities with costs of 

regulated facilities owned by non-government entities. The Agency evaluated costs per 

facility on the basis of both average and maximum annualized cost. The costs for 

facilities owned by small government entities wereare less than those estimated for 

facilities owned by large government entities, or for facilities owned by small or large 

non-government entities. On this basis, EPA concludedinterprets these findings to 

indicate that the compliance cost requirements of today’sfinal rule will not significantly 

or uniquely or disproportionately affect small governments. 

Because no manufacturer is government-owned, EPA conducted this analysis for 

electric generators only. 

a. Government-Owned Electric Generators by Ownership and Entity-Size Category 

Exhibit XI-7 provides an estimate of the number of non-federal government 

entities that own electric generators, by ownership type and size of government entity. As 
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presented in Exhibit XI-7, 27 large government entities own 45 electric generators, and 

19 small government entities own 19 electric generators. Of the 64 facilities that are 

owned by government entities, 47 are owned by municipalities, 11 are owned by States, 

and 6 are owned by other political subdivisions. No regulated facility is owned by a 

Tribal government.

Exhibit XI-7. Number of government entities and government-owned electric generators 

Ownership type Exhibit XI-7 provides an estimate of the 

number of non-Federal government entities 

that own electric generators, by ownership 

type and size of government entity. As 

presented in Exhibit XI-7, large government 

entities own 45 electric generators, and 

small government entities own 20 electric 

generators. Of the 65 facilities owned by 

government entities, 48 are owned by 

municipalities, six are owned by States and 

11 are owned by other political subdivisions. 

Tribal governments own no regulated 

facilities.

Exhibit XI-7. Number of government entitiesa-owned 

electric generators, by Size of Governmenta

Number of facilitiesb c

Entity Type Large Small Tota

l 

LargeSmal

l

Total

Deleted Cells

Deleted Cells

Split Cells

Deleted Cells

Deleted Cells

Deleted Cells
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Municipality 1

9

18 37 29 1819 4748

State Government 56 10 6 1

0

1 1

1

Other Political Subdivision 310 01 311 6 0 6

Tribal Government 0 0 0 0 0 0

Total 2

7

19 46 45 1920 6465

a

 Counts of entities that own explicitly and implicitly analyzed electric generators; these are not weighted entity 

counts. For details see EA Appendix H. 

b

Countsa Counts of explicitly and implicitly analyzed electric generators; these are not weighted estimates. For details, see 

EA Appendix H.

c

Facility size is the size of its parent entity.

b. Compliance Costs for Electric Generators Owned by Small Government Entities 

Exhibit XI-8 presents total, average annualized compliance costs, and maximum 

annualized compliance costs of the final rule for regulated facilities owned by 

government (State, local, and Tribal governments) and non-government entities by entitysize category. For the existing unitsunit provision of the final rule, EPA estimates that 

small government entities will incur a total annualized cost of $2.86 million, which is less 

thancompared to the total cost of $7.28.6 million incurred by large government entities or 

the total cost of $9.2and $8.5 million incurred by small private entities. On a per facility 

basis, EPA estimates that a facility owned by a small government entitiesentity will on 

average incur a cost of less than $0.2 million with a maximum of $0.5 million. These 

costs are less than those estimated The Agency estimates that for facilitiesa facility

owned by either large government entities (more thanentity, the average cost of the 

Deleted Cells

Deleted Cells

Deleted Cells

Deleted Cells

Deleted Cells

Deleted Cells

Deleted Cells

Deleted Cells

Deleted Cells
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existing provision of the final rule will be $0.2 million per facility with a maximum of 

$1.23 million) or, while for a facility owned by a small private entities ($entity the 

average cost will be $0.42 million per facility with a maximum of $2.1.4 million)..183

Again, overall, EPA therefore concludes that the compliance requirements of the existing 

unitsunit provision of today’s rule do not significantly or uniquely affect small 

governments in comparison to either large governments or small private entities. For 

details of this analysis, see the EA Chapter 1211. 

Exhibit XI-8. Electric generators and compliance costs by ownership type and size (in millions, 2011 dollars) 

Ownership type 

Entity 

size 

Number of 

facilities 

(weighted)a

Total compliance 

costs 

Average cost 

per facilityd

Maximum 

facility coste

Final Rule 

Government (excluding 

federalFederal) Small 

16 $2.86 $0.2 $0.5 

Large 

3237 $7.28.6 $0.2 $1.23

Privateb

Small 

2353 $9.28.5 $0.42 $2.1.4

Large 

45942

3

$263.0184.3 $0.64 $105.0 

All Facilitiesc 544 $296.7220 $0.54 $105.0 

 

183 Excluding federalFederal government entities and regulated facilities they own. 
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Ownership type 

Entity 

size 

Number of 

facilities 

(weighted)a

Total compliance 

costs 

Average cost 

per facilityd

Maximum 

facility coste

a

Facility counts are weighted estimates and differ from the values reported in Exhibit XI-7, which are un-weighted counts and 

reflect information for both explicitly and implicitly analyzed electric generators. Sample-weighted values are reported in this 

table because costs were developed only for the explicitly analyzed electric generators. For details on development of sample 

weights, see EA Appendix H. 

b

Facility counts and cost estimates reported for the private sector include 28 facilities owned by rural electric cooperatives. 

c

Facility counts and cost estimates reported for All Facilities include 14 facilities owned by the federalFederal government and 

costs estimated for these facilities. 

d

EPA calculated average cost per facility using the total number of regulated facilities owned by entities in a given ownership 

category. 

e

Reflects maximum of un-weighted costs to explicitly analyzed facilities only. 

3. Administrative Costs 

Section 316(b) requirements are implemented through the NPDES permit 

program. EPA estimates that 46 States and one territory—the relevant jurisdictions with 

NPDES permitting authority under CWA section 402(b)—will incur costs to administer 

the final rule.184 EPA estimates that States and territories will incur costs for 

implementing the requirements of today’s rule in four activity categories: (1) start-up 

activities to learn and understand the requirements of today’s regulation and to implement 

administrative structures and procedures for administering the regulation; (2) firstinitial

permit issuance activities; (3) annual activities, including monitoring, reporting and 

recordkeeping; and (4) non-annually recurring permit-related activities. Exhibit XI-9 

 

184 Federal government permitting authorities will also incur costs to administer the rule. As stated earlier in 

this section, consistent with UMRA analysis requirements, EPA did not account for costs to federalFederal

entities in the UMRA analysis. 
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presents total annualized costs for each type of administrative activity. EPA estimates 

that State and local government entities will incur annualized costs of $1.0.9 million to 

administer the final rule for electric generators and manufacturers. Monitoring, reporting 

and recordkeeping costs compose the largest share of administrative costs. 

Exhibit XI-9. Annualized government administrative costs (in millions, 2011 dollars) 

 Cost 

Activity 

Electric generators Manufacturers 

Total 

 Start-up Activities 

NA NA $0.0a

FirstInitial Permit Issuance Activities $0.2 $0.2 $0.4 

Annual Monitoring, Reporting and 

Recordkeeping Activities 

$0.32 $0.2 $0.5 

Non-Annually Recurring Permit-Related 

ActivitiesActivitiesb

$0.0b $0.0

b 

$0.1

Total $0.65 $0.4 $1.0.9

a

 Costs associated with start-up activities are estimated for both Electric Generatorselectric generators and 

Manufacturersmanufacturers; these costs are less than $20,000. 

b

 Costs are less than $50,000.

E. Executive Order 13132: Federalism 

Under E.O. 13132, EPA may not issue an action that has federalism implications, 

that imposes substantial direct compliance costs on the State and local governments, and 

that is not required by statute, unless the federalFederal government provides the funds 

necessary to pay the direct compliance costs incurred by State and local governments, or 

EPA consults with State and local officials early in the process of developing the final 

rule. 
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The final rule does not have federalism implications. It will not have substantial 

direct effects on the States, on the relationship between the national government and the 

States, or on the distribution of power and responsibilities among the various levels of 

government, as specified in E.O. 13132.This final rule would not alter the basic StatefederalFederal scheme established in the CWA under which EPA authorizes States to 

carry out the NPDES permitting program. Prior to this rule, authorized States were 

required to issue NPDES permits including requirements for CWISs on a case-by-case 

BPJ basis. 40 CFR. 125.90(b). EPA expects that today’s rule will have little to no effect 

on the relationship between, or the distribution of power and responsibilities among, the 

federalFederal and State governments. 

EPA estimated the rule’s burden on State and local governments. EPA estimates 

an average annual burden of $1.0.9 million, for StatesState and local governments to 

collectively administer the existing and new units provisionsunit provision of the final 

rule.185 The rule will also impose a compliance cost burden on State and local 

governments, if those government entities own facilities that are subject to today’s rule. 

EPA has identified 48554 regulated facilities that are owned by State or local government 

entities; the Agency estimates that under the existing unitsunit provision of the final rule 

these facilities will incur an average annual compliance cost of approximately $0.2 

 

185 This estimate does not include costs to administer the new unit provision of the final rule; however, EPA 

expects these costs to be small. 
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million per facility.186 ThusBecause this rule does not have federalism implications, the 

requirements of section 6 of E.O.13132 do not apply to this rule. 

F. Executive Order 13175: Consultation and Coordination with Indian Tribal 

Governments 

This action does not have tribalTribal implications, as specified in E.O. 13175 (65 

FR 67249, November 9, 2000). It would not have substantial direct effects on tribalTribal

governments, on the relationship between the federalFederal government and the Tribes, 

or the distribution of power and responsibilities between the federalFederal government 

and Tribes as specified in E.O. 13175. The national cooling water intake structure 

standards would be implemented through permits issued under the NPDES program. No 

tribalTribal governments are authorized pursuant to CWA section 402(b) to implement 

the NPDES program. In addition, EPA’s analyses show that tribalTribal governments 

own no facilities subject to today’s rule; thus, this rule does not affect Tribes in any way 

now or in the foreseeable future. Thus, E.O. 13175 does not apply to this action. 

G. Executive Order 13045: Protection of Children from Environmental Health 

Risks and Safety Risks 

This action is not subject to E.O. 13045 because it does not establish an 

environmental standard intended to mitigate health or safety risks. This rule establishes 

 

186 Cost values were calculated over the 51-year analysis period used for analysis of social costs, discounted 

and annualized using a rate of 7 percent (see EA Chapters 87 and 1211). 
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requirements for cooling water intake structures to protect aquatic organismsthe 

environment. 

H. Executive Order 13211: Actions that Significantly Affect Energy Supply, 

Distribution, or Use 

E.O. 13211 (66 FR 28355, May 22, 2001) requires EPA to prepare and submit a 

Statement of Energy Effects to the Administrator of the Office of Information and 

Regulatory Affairs, Office of Management and Budget, for actions identified as 

significant energy actions. On the basis of the Office of Management and Budget’s 

guidance for assessing the potential energy impact of regulations,187 the Agency does not 

anticipateanticipates that today’s rule willmay have a significant adverse effect on the 

supply, distribution, or use of energy;, thus, it will not constitute requiring EPA to include

a significant regulatory action under E.O. 13211Statement of Energy Effects. 

The Agency assessed the energy effects of today’s rule, specifically, the rule’s 

effect on energy supply, distribution or use in the electric power sector, as required under 

E.O. 13211. In its energy-effects assessment, EPA relied on Integrated Planning Model 

(IPM) analyses undertaken by EPA for the proposed rule, specifically Proposal Option 1, 

which aligns closely with the final rule in terms of the required performance standards. 

Asfinal rule. Based on that analysis, described in Section IX.(D.3)(1)(d) of this preamble 

(Assessment of the Impacts in the Context of Electricity Markets), EPA used IPM 

 

187http://www.whitehouse.gov/omb/memoranda/m01_27.html. 
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analysis results from the proposed rule) and in more detail in supporting its decisions 

concerning the final rule. Based on the analysis for Proposal Option 1Chapter 6 of the EA 

report, EPA finds again that the final rule’s compliance requirements would not cause 

effects in of the final rule may affect the electric power sector in ways that would 

constitute a significant adverse effect under E.O. 13211. As discussed in Section IX.D.3, 

the Agency’s analysis found that Proposal Option 1 would not reduce electricity 

production in excess of 1 billion kWh hours per year (or one thousand GWh) or in excess 

of 500 MW of installed capacity and, therefore, would not constitute a significant 

regulatory action under E.O. 13211. EPA assesses that the earlier findings from IPM 

provide insight into the energy effects of today’s rule; indeed, because of the final rule’s 

lower cost, operational effects, and greater flexibility in compliance schedule, compared 

to Proposal Option 1, EPA assesses that the final rule would have lower energy effects 

than Proposal Option 1 and therefore will not cause a significant adverse effect as defined 

under E.O. 13211.thus includes a Statement of Energy Effects in the economic analysis. 

The Agency’s analysis found that the final rule will not reduce electricity 

production in excess of 1 billion kWh hours per year (or one thousand GWh), will not 

increase the cost of energy production in excess of 1 percent, will not increase 

dependence on foreign supply of energy, and will not significantly affect domestic coal 

production. However, the final rule will result in net retirement of 998 MW of generating 

capacity, which exceeds 500 MW of installed capacity, the threshold of significant 

adverse effect identified in the OMB Implementation Guidance for E.O. 13211. EPA 

notes that, with only one exception, these retirements involve older, less efficient 
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generating units with very low capacity utilization rates. The 998 MW of net retired 

capacity is replaced by 589 MW of new capacity; therefore, because older and less 

efficient capacity is replaced by new, more energy-efficient, and less polluting capacity, 

these retirements mean that 409 MW less capacity is needed to fulfill the same demand. 

For more detail on the estimated energy effects of the final rule, see Chapter 12 of 

the EA, which is in the public docket. 

I. National Technology Transfer and Advancement Act 

Section 12(d) of the National Technology Transfer and Advancement Act of 

1995, Public Law No. 104-113, 12(d) (15 U.S.C. 272 note) directs EPA to use voluntary 

consensus standards in its regulatory activities unless doing so would be inconsistent with 

applicable law or otherwise impractical. Voluntary consensus standards are technical 

standards (e.g., materials specifications, test methods, sampling procedures, and business 

practices) that are developed or adopted by voluntary consensus standards bodies. The 

National Technology Transfer and Advancement Act directs EPA to provide Congress, 

through the Office of Management and Budget, explanations when the Agency decides 

not to use available and applicable voluntary consensus standards. 

This final rulemaking may involve technical standards, for example, in measuring 

impingement and entrainment. Nothing in this final rule would prevent the use of 

voluntary consensus standards for such measurements. EPA encourages permitting 

authorities and regulated entities to use voluntary consensus standards, where they are 

available. 
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J. Executive Order 12898: Federal Actions to Address Environmental Justice in 

Minority Populations and Low-Income Populations 

E.O. 12898 (59 FR 7629, February 16, 1994) establishes federalFederal executive 

policy on environmental justice. Its main provision directs federalFederal agencies, to the 

greatest extent practicable and permitted by law, to make environmental justice part of 

their mission by identifying and addressing, as appropriate, disproportionately high and 

adverse human health or environmental effects of their programs, policies, and activities 

on minority populations and low-income populations in the United States. 

EPA has determined that today’s rule will not have disproportionately high and 

adverse human health or environmental effects on minority or low-income populations. 

Specifically, the final rule increases the level of environmental protection for all affected 

populations and has no high and adverse human health or environmental effects on any 

population, including any minority or low-income population. Because EPA expects that 

this final rule will help to preserve the health of aquatic ecosystems near regulated 

facilities, EPA expects that all populations, including minority and low-income 

populations, will benefit from improved environmental conditions. 

To meet the objectives of E.O. 12898, EPA assessed whether today’s rule could 

distribute benefits among population subgroups in a way that is significantly 

unfavorableless favorable to low-income and minority populations. EPA compared key 

demographic characteristics of affected substate populations to those demographic 

characteristics at the State level. If EPA had found that the demographic profile of the 

substate benefit population is composed of a significantly lower share of low-income 
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and/or minority populations than the State’s general population, EPA might have 

assessed the final rule as yielding an unfavorable distribution of benefits, from the 

perspective of the public policy principles of E.O. 12898. The two sets of demographic 

variables of interest for this environmental justice analysis are race and ethnicity, and 

annual household income, which are the variables in the Fish Consumption Pathway 

Module that best capture the minority and low-income aspects of the affected 

populations.188,189 EPA compared variable averages at the substate and State levels to 

determine whether the demographic profile of the affected population is consistent with 

the State profile (for details, see EA Chapter 1312). 

The comparison of minority populations affected by the regulated facilities to the 

affected States’ overall populations showed no statistically significant difference between 

these groups. While low-income populations constitute a lower fraction of the benefit 

population than of the State’s overall population in many States, the two groups are not 

significantly different. EPA thus determined that the final rule does not systematically 

discriminate against, or exclude or deny participation of, the lower income population 

 

188 Annual household income data in the FCP Module are available for the following categories: less than 

$10,000; $10,000 to $19,999; $20,000 to $24,999; $25,000 to $29,999; $30,000 to $34,999; $35,000 to 

$39,999; $40,000 to $49,999; $50,000 to $74,999; $75,000 to $99,999; and more than $100,000. For this 

analysis and previous 316(b) rule analyses, these categories were combined into low- and not low-income 

groups based on the U.S. Department of Health and Human Services’ poverty guidelines for a family of 

four living in the contiguous United States or D.C. The current (2013) poverty guideline is $23,550, which 

falls near the upper end of the $20,000 to $24,999 income range (U.S. HHS, 2013). For the current 

analysis, EPA used $25,000 as the threshold for separating populations into low- and not low-income 

groups. 

189 Race and ethnic categories used in the analysis include white non-Hispanic, white Hispanic, black or 

African American, Asian or Native Hawaiian or Other Pacific Island, and American Indian and Alaska 

Native. 
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group or the minority population group in the benefits of the final rule in a way that 

would be contrary to the intent of E.O. 12898. Overall, EPA thus concluded that the final 

rule is consistent with the policy intent of E.O. 12898. Anecdotally, minority (e.g., Native 

American) and low-income populations might be more likely to include a larger 

proportion of subsistence fishermen. Because this rule will increase abundance of all fish 

species in the areas affected by cooling water intakes, it might provide a benefit to 

subsistence fishermen. To the extent that minority and low-income populations are overrepresented in this group, they might especially benefit from this rule. 

K. Executive Order 13158: Marine Protected Areas 

E.O. 13158 (65 FR 34909, May 31, 2000) requires EPA to “expeditiously propose 

new science-based regulations, as necessary, to ensure appropriate levels of protection for 

the marine environment.” EPA may take action to enhance or expand protection of 

existing marine protected areas and to establish or recommend, as appropriate, new 

marine protected areas. The purpose of this executive order is to protect significant 

natural and cultural resources in the marine environment, which means “those areas of 

coastal and ocean waters, the Great Lakes and their connecting waters, and submerged 

lands thereunder, over which the United States exercises jurisdiction, consistent with 

international law.” 

Today’s rule recognizes the biological sensitivity of tidal rivers, estuaries, oceans, 

and the Great Lakes, and their susceptibility to adverse environmental impacts from 

cooling water intake structures. The rule provides requirements to minimize adverse 

environmental impacts for cooling water intake structures on these types of waterbodies. 
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EPA used GIS data of the locations of MPAs (Marine Protected Areas) from the 

national MPA program (http://www.mpa.gov/helpful_resources/inventory.html) to locate 

regulated facilities in MPAs. Under the final rule, 60percent60 percent of regulated 

facilities in MPAs obtain reductions in impingement mortality. As noted above, because 

of EPA’s assumption that facilities with impoundments will not need to install 

compliance technology, this may be an underestimate. EPA cannot estimate reductions in 

entrainment because they would be based on site-specific determinations of BTA. 

Therefore, EPA expects that today’s rule will advance the objective of the executive 

order to protect marine areas. For more details on this analysis and analysis results, see 

EABA Chapter 138. 

L. Congressional Review Act 

The Congressional Review Act, 5 U.S.C. 801 et seq., as added by the Small 

Business Regulatory Enforcement Fairness Act of 1996, generally provides that before a 

rule may take effect, the agency promulgating the rule must submit a rule report, which 

includes a copy of the rule, to each House of the Congress and to the Comptroller 

General of the United States. EPA will submit a report containing this rule and other 

required information to the U.S. Senate, the U.S. House of Representatives, and the 

Comptroller General of the United States prior to publication of the rule in the Federal 

Register. A Majormajor rule cannot take effect until 60 days after it is published in the 

Federal Register. This action is a “major rule” as defined by 5 U.S.C. 804(2). This rule 

will be effective [INSERT DATE 60 DAYS AFTER DATE OF PUBLICATION IN 

THE FEDERAL REGISTER]. 
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EO12866_Cooling Water Intakes_2040_Final_Rule_20130722

List of Subjects 

40 CFR Part 122 

Environmental protection, Administrative practice and procedure, Confidential business 

information, Hazardous substances, Reporting and recordkeeping requirements, Water 

pollution control. 

40 CFR Part 125 

Environmental protection, Cooling water intake structure, Reporting and recordkeeping 

requirements, Waste treatment and disposal, Water pollution control. 

Dated: 

_____________________ 

XXXGina McCarthy, Administrator. 

For reasons set out in the preamble, Chapter I of Title 40 of the Code of Federal 

Regulations is amended as follows: 

PART 122--EPA ADMINISTERED PERMIT PROGRAMS: THE NATIONAL 

POLLUTANT DISCHARGE ELIMINATION SYSTEM 

1. The authority citation for part 122 continues to read as follows: 

AUTHORITY: The Clean Water Act, 33 U.S.C. 1251 et seq. 
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2. The suspension of 40 CFR 122.21(r)(1)(ii) and (r)(5), published on July 9, 2007 (72 

FR 37109) is lifted. 

3. Section 122.21 is amended as follows: 

 a. Revising paragraph (r)(1)(i)).

 b. Revising paragraph (r)(1)(ii). 

 c. Revising paragraphs (r)(2) introductory text, (r)(2)(i) though (iii), and (r)(3) 

through (5). 

 d. Adding paragraphs (r)(4)(ix) through (r)(4)(xii), replacing paragraph (r)(5), 

and adding paragraphs and (r)(6) through (r)(14). 

§ 122.21 Application for a permit (applicable to State programs, see § 123.25). 

* * * * * 

 (r) * * * 

 (1) * * * 

(i) New facilities with new or modified cooling water intake structures. New 

facilities (other than offshore oil and gas extraction facilities) with cooling water intake 

structures as defined in part 125, subpart I of this chapter, must submit to the Director for 

review the information required under paragraphs (2) (except (r)(2)(iv)), (3,), and (4)

(except (r)(4)(ix), (r)(4)(x) ), (r)(4)(xi), and (r)(4)(xixii)) of this section and § 125.86 of 

this chapter as part of the permit application. *New offshore oil and gas extraction 

facilities with cooling water intake structures as defined in part 125, subpart N, of this 

chapter that are fixed facilities must submit to the Director for review the information 

required under paragraphs (r)(2) (except (r)(2)(iv)), (3), and (4) (except (r)(4)(ix), 
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(r)(4)(x), (r)(4)(xi) and (r)(4)(xii)) of this section and § 125.136 of this chapter as part of 

their permit application.* * * 

 (ii) Existing facilities. 

 (A) All existing facilities. as defined at 125.92 subject to the requirements of 

125.94. The owner or operator of an existing facility that operates or intends to operate a 

closed-cycle recirculating system as defined at 40 CFR 125.92 must provide only the 

information required under paragraphs (r)(2), (3), (4), (5), (6), and (8) of this section. All 

other owners or operators of an existing facility must submit the information described 

below. 

defined at 40 CFR 125.92(k) (A) All existing facilities. The owner or operator of 

an existing facility must submit to the Director for review the information required under 

paragraphs (r)(2), (3), () and (3) and applicable provisions of paragraphs (4), (5), (6), (7) 

and (8) of this section. 

 (B) Existing facilities greater than 125 mgd AIF. In addition., the owner or 

operator of an existing facility that withdraws greater than 125 mgd actual intake flow 

(AIF), as defined at 40 CFR 125.92, (a), of water for cooling purposes must also submit 

to the Director for review the information required under paragraphs (r)(7),) (9), (10), 

(11), (12), and (13) of this section. In addition, unless waived by the Director, this owner 

or operator must also submit the information required under paragraph (r)(11). 

Alternatively, the owner or operator may choose not to provide the information under 

paragraphs (r)(7), (9), (10), (11), (12) and (13), for example, ifIf the owner or operator of 

an existing facility choosesintends to comply with the BTA (best technology available) 
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standards for entrainment using a closed-cycle recirculating system. In the absence of this 

information, the Director will base the site-specific entrainment requirement on a closedcycle recirculating system. as defined at 40 CFR 125.92(c), the Director may reduce or 

waive some or all of the information required under paragraphs (r)(9) to (13). 

 (C) Additional information. The owner or operator of an existing facility must 

also submit such additional information as the Director determines is necessary pursuant 

to 40 CFR 125.98(i). 

 (D) New units at existing facilities. The owner or operator of a new unit at an 

existing facility, as defined at 40 CFR 125.92,(u), must submit or update any information 

previously provided to the Director by submitting the information required under 

paragraphs (r)(2), (3), (4), (5), (8), (14) and applicable provisions of paragraphs (r)(4), (6) 

and (r)(7). Requests for and approvals of alternative requirements sought under 40 CFR 

125.94(e)(4) 2) or 125.98(b)(7)of this chapter must be submitted with yourthe permit 

application. 

 (E) New units at existing facilities not previously subject to part 125. The owner 

or operator of a new unit as defined at §40 CFR 125.92(u) at an existing facility not 

previously subject to part 125 that increases the total capacity of the existing facility to 

more than 2 mgd DIF must submit the information required under paragraphs (r)(2), (3), 

(4), (5), (8) and applicable provisions of (r)(4), (6) and (7) of this section 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 
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the additional capacity will result in the existing facility withdrawing greater than 125 

mgd AIF. Requests for alternative requirements under 40 CFR 125.94(e)(42) or 

125.98(b)(7) of this chapter must be submitted with your permit application.the permit 

application. If the total capacity of the facility will increase to more than 125 mgd AIF, 

the owner or operator must also submit the information required in paragraphs (r)(9) to 

(13). If the owner or operator of an existing facility intends to comply with the BTA 

(best technology available) standards for entrainment using a closed-cycle recirculating 

system as defined at 40 CFR 125.92(c), the Director may reduce or waive some or all of 

the information required under paragraphs (r)(9) to (13).

 (F) If the owner or operator of an existing facility plans to retire the facility 

before the current permit expires, then the requirements of paragraph (r)(1)(ii)(A), (B), 

(C), (D) and (E) do not apply. 

 (G) 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 

the requirements of paragraphs (r)(7), (9), (10), (11), (12) and (13) pending a signed 

certification statement from the owner or operator of the facility specifying the last 

operating date of the facility. 

 (H) All facilities. The owner or operator of any existing facility or new unit at 

any existing facility must also submit with its permit application all information received 

as a result of any communication with a Field Office of the Fish and Wildlife Service 

and/or Regional Office of the National Marine Fisheries Service. 

* * * * * 
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 (4) * * *

 (ix (ix) In the case of the owner or operator of an existing facility or new 

unit at an existing facility, the Source Water Baseline Biological Characterization Data

is the information in (i) through (xii). 

 (x) For the owner or operator of an existing facility, identification of protective 

measures and stabilization activities that have been implemented, and a description of 

how these measures and activities affected the baseline water condition in the vicinity of 

the intake. 

 (xxi) For the owner or operator of an existing facility, a list of fragile species, as 

defined at 40 CFR 125.92,(m), at yourthe facility. YouThe applicant need only identify 

those species not already identified as fragile at 40 CFR 125.92.(m). New units at an 

existing facility are not required to resubmit this information if the cooling water 

withdrawals for the operation of the new unit isare from an existing intake. 

 (xixii) For the owner or operator of an existing facility subject to 40 CFR part 

125, subpart J, of this chapter, whosethat has obtained incidental take exemption or 

authorization for its cooling water intake is within the range of habitat of one or more 

federally listed threatened or endangered species, a certification that the information at 

122.21(r)(4)(vi) was sent directly to the relevant regional offices ofstructure(s) from the 

U.S. Fish and Wildlife Service or the National Marine Fisheries Service., any information 

submitted in order to obtain that exemption or authorization may be used to satisfy the 

permit application information requirement of paragraph 40 CFR 125.95(f) if included in 

the application. 
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 (5) Cooling Water System Data. The owner or operator of an existing facility 

must submit the following information for each cooling water intake structure used or 

intended to be used: 

 (i) A narrative description of the operation of the cooling water system and its 

relationship to cooling water intake structures; the proportion of the design intake flow 

that is used in the system; the number of days of the year the cooling water system is in 

operation and seasonal changes in the operation of the system, if applicable; at existing 

facilities, the proportion of design intake flow for contact cooling, non-contact cooling, 

and process uses; for existing facilities, a distribution of water reuse to include cooling 

water reused as process water, process water reused for cooling, and the use of gray water 

for cooling; for existing facilities, a description of reductions in total water withdrawals 

including cooling water intake flow reductions already achieved through minimized 

process water withdrawals; for existing facilities, a description of any cooling water that 

is used in a manufacturing process either before or after it is used for cooling, including 

other recycled process water flows; for existing facilities, the proportion of the source 

waterbody withdrawn (on a monthly basis); 

 (ii) Design and engineering calculations prepared by a qualified professional 

and supporting data to support the description required by paragraph (r)(5)(i) of this 

section; and 

 (iii) At existing facilities, descriptionDescription of existing impingement and 

entrainment technologies or operational measures and a summary of their performance, 
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including but not limited to reductions in impingement mortality and entrainment due to 

intake location and reductions in total water withdrawals and usage. 

 (6) Chosen Method(s) of Compliance with Impingement Mortality Standard. 

The owner or operator of the facility must identify the chosen compliance method for 

yourthe entire facility; alternatively, youthe applicant must identify the chosen 

compliance method under 40 CFR 125.94(c) for each cooling water intake structure at 

your facility.its facility. The applicant must identify any intake structure for which a BTA 

determination for Impingement Mortality under 40 CFR 125.94 (c)(11) or (12) is 

requested. In addition, the owner or operator that chooses to comply via 40 CFR 125.94 

(c)(5) or (6) must also submit an impingement technology performance optimization 

study as described below: 

 (i) If you choosethe applicant chooses to comply with 40 CFR 125.94(c)(5), 

yoursubject to the flexibility for timing provided in 40 CFR 125.95(a)(2), the

impingement technology performance optimization study must include two years of 

biological monitoringdata collection measuring the reduction in impingement mortality 

achieved by yourthe modified traveling screens as defined at 40 CFR 125.92(s) and 

demonstrating that yourthe operation has been optimized to minimize impingement 

mortality. You must include a A complete description of yourthe modified traveling 

screens and associated equipment must be included, including, for example, type of 

mesh, mesh slot size, pressure sprays and fish return mechanisms. You must also provide 

aA description of any monitoringbiological data collection and monitoringdata collection

approach used in measuring impingement mortality, including: 
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 (A) For this demonstration, you must samplebe included: 

 (A) Collecting data no less frequently than monthly. The Director may establish 

more frequent monitoringdata collection; 

 (B) Biological monitoring. Biological monitoring must bedata collection

representative of the impingement and the impingement mortality at the intakes subject to 

this provision; 

 (C) A taxonomic identification to the lowest taxon possible of all organisms to 

be monitoredcollected; 

 (D) The method in which naturally moribund organisms are identified and taken 

into account; 

 (E) The method in which mortality due to holding times is taken into account; 

 (F) If yourthe facility entraps fish or shellfish, you musta count theof

entrapment of organisms, as defined at 40 CFR 125.92(j), as impingement mortality; and

 (G) The percent impingement mortality reflecting optimized operation of 

yourthe modified traveling screen and all supporting calculations. 

 (ii) If you choosethe applicant chooses to comply with 40 CFR 125.94(c)(6), 

yourthe impingement technology performance optimization study must include biological 

monitoringdata measuring the reduction in impingement mortality achieved by operation 

of yourthe system of technologies, operational measures and best management practices,

and demonstrating that operation of yourthe system has been optimized to minimize 

impingement mortality. This system of technologies, operational measures and best 

management practices may include flow reductions, seasonal operation, unit closure, 
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credit for intake location, and behavioral deterrent systems. YouThe applicant must 

document how each system element contributes to yourthe system’s performance. 

YouThe applicant must include a minimum of two years of biological monitoringdata

measuring the reduction in impingement mortality achieved by yourthe system. YouThe 

applicant must also include a description of any sampling or monitoringdata collection

approach used in measuring the rate of impingement, impingement mortality, or flow 

reductions. 

 (A) Rate of Impingement. If yourthe demonstration relies in part on a credit for 

reductions in the rate of impingement in yourthe system, youthe applicant must provide 

an estimate of those reductions to be used as credit towards reducing impingement 

mortality, and any relevant supporting documentation, including previously collected 

biological data, performance reviews, and previously conducted performance studies not 

already submitted to the Director as part. The submission of (r)(7). You must accompany 

studies more than 10 years old withmust include an explanation of why the data isare still 

relevant and representative of conditions at yourthe facility and explain how the data 

should be interpreted using the definitions of impingement and entrapment at 40 CFR 

125.92.(n) and (j), respectively. The estimated reductions in rate of impingement must be 

based on a comparison of yourthe system to a once-through cooling system with a 

traveling screen whose point of withdrawal from the surface water source is located at the 

shoreline of the source waterbody. In addition, youFor impoundments that are waters of 

the United States in whole or in part, the facility’s rate of impingement must be measured 

at a location within the cooling water intake system that the Director deems appropriate. 
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In addition, the applicant must include two years of biological monitoringdata collection

demonstrating the rate of impingement resulting from yourthe system. For this 

demonstration, youthe applicant must monitorcollect data no less frequently than 

monthly. The Director may establish more frequent monitoringdata collection. 

 (B) Impingement Mortality. If yourthe demonstration relies in part on a credit 

for reductions in impingement mortality already obtained at yourthe facility, youthe 

applicant must include two years of biological monitoringdata collection demonstrating 

the level of impingement mortality yourthe system is capable of achieving. YouThe 

applicant must submit any relevant supporting documentation, including previously 

collected biological data, performance reviews, and previously conducted performance 

studies not already submitted to the Director. The applicant must provide a description of 

any sampling or monitoringdata collection approach used in measuring impingement 

mortality. In addition, for this demonstration youthe applicant must: 

 (1) MonitorCollect data no less frequently than monthly. The Director may 

establish more frequent monitoringdata collection; 

 (2) Conduct biological monitoringdata collection that is representative of the 

impingement and the impingement mortality at an intake subject to this provision. In 

addition, youthe applicant must describe how the location of the cooling water intake 

structure in the water bodywaterbody and the water column are accounted for in yourthe

points of monitoringdata collection; 

 (3) Include a taxonomic identification to the lowest taxon possible of all 

organisms to be monitoredcollected; 
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 (4) Describe the method in which naturally moribund organisms are identified 

and taken into account; 

 (5) Describe the method in which mortality due to holding times is taken into 

account; and 

 (6) If yourthe facility entraps fish or shellfish, you musta count of the 

entrapment of organisms, as defined at 40 CFR 125.92(j), as impingement mortality. 

 (C) Flow reduction. If yourthe demonstration relies in part on flow reduction to 

reduce impingement, youthe applicant must include two years of intake flows, measured 

daily, as part of yourthe demonstration, and describe the extent to which flow reductions 

are seasonal or intermittent. YouThe applicant must document how the flow reduction 

results in reduced impingement. In addition, youthe applicant must describe how the 

reduction in impingement has reduced your impingement mortality. 

 (D) Total system performance. YouThe applicant must document the percent 

impingement mortality reflecting optimized operation of yourthe total system of 

technologies, operational measures, and best management practices and all supporting 

calculations. YourThe total system performance is the combination of the impingement 

mortality performance reflected in (A), (B), and (C) of this paragraph. 

 (7) Entrainment Performance Studies. The owner or operator of an existing 

facility must submit any previously conducted studies or studies obtained from other 

facilities addressing technology efficacy, through-plantfacility entrainment survival, and 

other entrainment studies. Any such submittals must include a description of each study, 

together with underlying data, and a summary of any conclusions or results. Any studies 
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conducted at other locations must include an explanation as to why the data from other 

locations are relevant and representative of conditions at your facility. If you submit In 

the case of studies more than 10 years old, youthe applicant must explain why the data 

isare still relevant and representative of conditions at yourthe facility and explain how the 

data should be interpreted using the definition of entrainment at 40 CFR 125.92.(h).

 (8) Operational Status. The owner or operator of an existing facility must 

submit a description of the operational status of each generating, production, or process 

unit that uses cooling water, including but not limited to: 

 (i) For power production or steam generation, descriptions of individual unit 

operating status including age of each unit, capacity utilization rate (or equivalent) for the 

previous 5 years (, including any extended or unusual outages that significantly affect 

current data for flow, impingement, entrainment, or other factors, including identification 

of any operating unit with a capacity utilization rate of less than 8 percent for each of the 

previous 5 years and maintained solely to generate power for emergency 

purposes),averaged over a 24-month block contiguous period, and any major upgrades 

completed within the last 15 years, including but not limited to boiler replacement, 

condenser replacement, turbine replacement, or changes to fuel type; 

 (ii) Descriptions of completed, approved, or scheduled uprates and Nuclear 

Regulatory Commission relicensing status of each unit at nuclear facilities; 

 (iii) For processesprocess units at your facility that use cooling water other than 

for power production or steam generation, if you intend to use reductions in flow or 

changes in operations to meet the requirements of 40 CFR 125.94(c), descriptions of 
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individual production processes and product lines, operating status including age of each 

line, seasonal operation, including any extended or unusual outages that significantly 

affect current data for flow, impingement, entrainment, or other factors, any major 

upgrades completed within the last 15 years, and plans or schedules for decommissioning 

or replacement of process units or production processes and product lines; 

 (iv) For all manufacturing facilities, descriptions of current and future 

production schedules; and 

 (v) Descriptions of plans or schedules for any new units planned within the next 

5 years. 

 (9) Entrainment Characterization Study. The owner or operator of an existing 

facility that withdraws greater than 125 mgd AIF, where the withdrawal of cooling water 

is measured at a location within the cooling water intake structure that the Director deems 

appropriate, must develop for submission to the Director an Entrainment 

Characterization Study that includes a minimum of two years of entrainment 

monitoringdata collection. The Entrainment Characterization Study must include the 

following components: 

 (Ai) Entrainment MonitoringData Collection Method. IdentificationThe study 

should identify and documentation ofdocument the monitoringdata collection period and 

frequency. IdentificationThe study should identify and documentation ofdocument

organisms monitoredcollected to the lowest taxon possible of all life stages of fish and 

shellfish that are in the vicinity of the cooling water intake structure(s) and are 

susceptible to entrainment, including any other organisms identified by the Director, and 
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any species protected under Federal, State, or Tribal Lawlaw, including threatened or 

endangered species with a habitat range withinthat includes waters in the vicinity of the 

cooling water intake structure. Biological monitoringdata collection must be 

representative of the entrainment at the intakes subject to this provision. The owner or 

operator of the facility must identify and document how the location of the cooling water 

intake structure in the water bodywaterbody and the water column are accounted for by 

the monitoringdata collection locations; 

 (Bii) Biological Entrainment Characterization. Characterization of all life 

stages of fish, shellfish, and any species protected under Federal, State, or Tribal Lawlaw

(including threatened or endangered species), including a description of their abundance 

and their temporal and spatial characteristics in the vicinity of the cooling water intake 

structure(s), based on sufficient data to characterize annual, seasonal, and diel variations 

in entrainment, including but not limited to variations related to climate and weather 

differences, spawning, feeding, and water column migration. This characterization may 

include historical data that are representative of the current operation of yourthe facility 

and of biological conditions at the site. Identification of all life stages of fish and shellfish 

shallmust include identification of any surrogate species used, and identification of data 

representing both motile and non-motile life-stages of organisms; 

 (Ciii) Analysis and Supporting Documentation. Documentation of the current 

entrainment of all life stages of fish, shellfish, and any species protected under Federal, 

State, or Tribal Lawlaw (including threatened or endangered species). The documentation 

may include historical data that are representative of the current operation of yourthe
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facility and of biological conditions at the site. Entrainment monitoringdata to support 

the facility’s calculations must be collected during periods of representative operational 

flows for the cooling water intake structure, and the flows associated with the 

monitoringdata collection must be documented. The method used to determine latent 

mortality along with data for specific organism mortality or survival that is applied to 

other life-stages or species must be identified. The owner or operator of the facility must 

identify and document all assumptions and calculations used to determine the total 

entrainment and entrainment mortality for that facility together with all methods and 

quality assurance/quality control procedures for monitoringdata collection and data 

analysis. The proposed monitoringdata collection and data analysis methods must be 

appropriate for a quantitative survey. 

 (10) Comprehensive Technical Feasibility and Cost Evaluation Study. The 

owner or operator of an existing facility that withdraws greater than 125 mgd AIF must 

develop for submission to the Director an engineering study of the technical feasibility 

and incremental costs of candidate entrainment control technologies. In addition, the 

study must include the following: 

 (i) Technical feasibility. An evaluation of the technical feasibility of closedcycle recirculating systems (cooling towersas defined at 40 CFR 125.92(c), fine mesh 

screens with a mesh size of 2mm2 millimeters or smaller, and water reuse or alternate 

sources of cooling water. In addition, this study must include: 

 (A) A description of all technologies and operational measures considered 

(including alternative designs of closed-cycle recirculating systems such as natural draft 
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cooling towers, mechanical draft cooling towers, hybrid designs, and compact or multicell arrangements); 

 (B) A discussion of land availability, including an evaluation of adjacent land 

and acres potentially available due to generating unit retirements, production unit 

retirements, other buildings and equipment retirements, and potential for repurposing of 

areas devoted to ponds, coal piles, rail yards, transmission yards, and parking lots; 

 (C) A discussion of available sources of process water, grey water, waste water, 

reclaimed water, or other waters of appropriate quantity and quality for use as some or all 

of the cooling water needs of yourthe facility; and 

 (D) Documentation of factors other than cost that may make a candidate 

technology impractical or infeasible for further evaluation. 

 (ii) Other entrainment control technologies. An evaluation of additional 

technologies for reducing entrainment may be required by the Director. 

 (iii) Cost evaluations. The study must include engineering cost estimates of all 

technologies considered in paragraphs (r)(10)(i) and (ii) of this section. Facility costs 

must also be adjusted to estimate social costs. All costs must be presented as the net 

present value (NPV) and the corresponding annual value. Costs must be clearly labeled as 

compliance costs or social costs. YouThe applicant must separately discuss facility level 

compliance costs and social costs, and provide documentation for the followingas 

follows: 

 (A) Compliance costs are calculated as after-tax, while social costs are 

calculated as pre-tax. Compliance costs include the facility’s administrative costs, 
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including costs of permit application, while the social cost adjustment includes the 

Director’s administrative costs. Any outages, downtime, or other impacts to facility net 

revenue, are included in compliance costs, while only that portion of lost net revenue that 

does not accrue to other producers can be included in social costs. Social costs must also 

be discounted using social discount rates of 3 percent and 7 percent. Assumptions 

regarding depreciation schedules, tax rates, interest rates, discount rates and related 

assumptions must be identified; 

 (B) Costs and explanation of any additional facility modifications necessary to 

support construction and operation of technologies considered in paragraphs (r)(10)(i) 

and (ii) of this section, including but not limited to relocation of existing buildings or 

equipment, reinforcement or upgrading of existing equipment, and additional 

construction and operating permits. Assumptions regarding depreciation schedules, 

interest rates, discount rates, useful life of the technology considered, and any related 

assumptions must be identified; and 

 (C) Costs and explanation for addressing any non-water quality environmental 

and other impacts identified in paragraph (r)(12) of this section. The cost evaluation must 

include a discussion of all reasonable attempts to mitigate each of these impacts. 

 (11) Benefits Valuation Study. Unless waived by the Director, theThe owner or 

operator of an existing facility that withdraws greater than 125 mgd AIF must develop for 

submission to the Director an evaluation of the magnitude of benefits, both monetized 

and non-monetized, of the candidate entrainment reduction technologies and operational 

measures evaluated in paragraph (r)(10) andincluding using the entrainment 
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characterization study Entrainment Characterization Study completed in § 122.21(r)(9) of 

this section, including . Each category of benefits must be described narratively, and 

when possible, benefits should be quantified in physical or biological units and 

monetized using appropriate economic valuation methods. The benefits valuation study 

must include, but is not limited to, the following elements: 

 (i) Incremental changes in the numbers of individual fish and shellfish, for all 

life stages, lost due to impingement mortality and entrainment as defined in 40 CFR 

125.92, for all life stages of each exposed species; 

 (ii) IdentificationDescription of basis for any estimates of changes in the stock 

sizes or harvest levels of commercial and recreational fish or shellfish species or forage 

fish species; 

 (iii) Description of basis for any monetized or qualitatively assessed values you 

assigned to changes in the stock size or harvest levels of commercial and recreational 

species, forage fish, and recreational fish or shellfish species, forage fish, and to any other 

ecosystem or non -use benefits; 

 (iiiiv) A discussion of mitigation efforts completed prior to [INSERT 

EFFECTIVE DATEeffective date of FINAL RULEfinal rule] including how long they 

have been in effect and how effective they have been; 

 (iv) Identificationv) 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; 
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 (v) Estimatesvi) Discussion, with quantification and monetization, where 

possible, of any benefits resultingexpected to result from any reductions in thermal 

discharges from entrainment technologies. 

 (12) Non-water Quality Environmental and Other Impacts Study. The owner or 

operator of an existing facility that withdraws greater than 125 mgd AIF must develop for 

submission to the Director a detailed facility-specific discussion of the changes in nonwater quality environmental and other impacts attributed to each technology and 

operational measure considered in paragraph (r)(10) of this section, including both 

impacts increased and impacts decreased. The study must include the following: 

 (i) Estimates of changes to energy consumption, including but not limited to 

auxiliary power consumption and turbine backpressure energy penaltiespenalty; 

 (ii) Estimates of air pollutant emissions and of the human health and 

environmental impacts associated with such emissions; 

 (iii) Estimates of changes in noise; 

 (iv) A discussion of impacts to safety, including documentation of the potential 

for plumes, icing, and availability of emergency cooling water; 

 (v) A discussion of facility reliability, including but not limited to facility 

availability, production of steam, impacts to production based on process unit heating or 

cooling, and reliability due to cooling water availability; 

 (vi) Significant changes in consumption of water, including a facility-specific 

comparison of the evaporative losses of both once-through cooling and closed-cycle 
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recirculating systems, and documentation of impacts attributable to changes in water 

consumption; and

 (vii) A discussion of all reasonable attempts to mitigate each of these factors. 

 (13) Peer Review. If you arethe applicant is required to submit studies under § 

122.21(r)(10) to (r)(12), youthe applicant must conduct an external peer review of 

youreach report to be submitted with yourthe permit application. YouThe applicant must 

select peer reviewers and notify the Director in advance of the peer review. The Director 

may disapprove of a peer reviewer or require additional peer reviewers. The Director may 

confer with EPA, Federal, State and Tribal fish and wildlife management agencies with 

responsibility for fish and wildlife potentially affected by the cooling water intake 

structure, independent system operators, and state public utility regulatory agencies, to 

determine which peer review comments must be addressed. YouThe applicant must 

provide an explanation for any significant reviewer comments not accepted. Peer 

reviewers must have appropriate qualifications and their names and credentials must be 

included in the peer review report. 

 (14) New Units. YouThe applicant must identify the chosen compliance method 

for yourthe new unit. In addition, the owner or operator that selects the BTA standards 

for entrainment for new units at 40 CFR 125.94 (e)(2) as theirits route to compliance 

must submit information to demonstrate entrainment reductions equivalent to 90 percent 

or greater of the reduction that could be achieved through compliance with 40 CFR 

125.94(e)(1). The demonstration must include the entrainment characterization 

studyEntrainment Characterization Study at § 122.21(r)(9). In addition, if data specific to 
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your facility indicates that compliance with the requirements of § 125.94 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, or significant adverse impacts on local energy markets, 

you must submit all supporting data as part of § 122.21(r)(14). The Director may 

determine that additional data and information, including but not limited to additional 

monitoring, must be included as part of § 122.21(r)(14). 

PART 125--CRITERIA AND STANDARDS FOR THE NATIONAL POLLUTANT 

DISCHARGE ELIMINATION SYSTEM 

4. The authority citation for part 125 continues to read as follows: 

AUTHORITY: The Clean Water Act, 33 U.S.C. 1251 et seq.; unless otherwise noted. 

Subpart I--[Amended] 

5. Section 125.84 is amended by: 

 a. Revising paragraph (c) introductory text; and 

 b. Revising paragraph (d)(1). 

The revised text reads as follows: 

§ 125.84 As an owner or operator of a new facility, what must I do to comply with 

this subpart? 

* * * * * 
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 (c) Track I requirements for new facilities that withdraw greater than 2 mgd 

and less than 10 mgd and that choose not to comply with paragraph (b) of this section.

You must comply with all the following requirements: 

* * * * * 

 (d) * * * 

 (1) You must demonstrate to the Director that the technologies employed will 

reduce the level of adverse environmental impact from your cooling water intake 

structures to a level comparable to that which you would achieve were you to implement 

the requirements of paragraphs (b)(1) and (2) of this section. This demonstration must 

include a showing that the impacts to fish and shellfish, including important forage and 

predator species, within the watershed will be comparable to those which would result if 

you were to implement the requirements of paragraphs (b)(1) and (2) of this section. The 

Director will consider information provided by any fishery management agency and may 

also consider data and information from other sources. 

* * * * * 

6. Section 125.86 is amended as follows: 

 a. Revise paragraph (a)(1)(ii). 

 b. Revise paragraph (b)(3) introductory text. 

 c. Revise paragraph (b)(4)(iii), leaving subparagraphs (A), (B)), and (C) 

unchanged. 

 d. Remove and reserve paragraph (c)(2)(ii). 

 e. Remove and reserve paragraph (c)(2)(iv)(C). 
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 f. Remove and reserve paragraph (c)(2)(iv)(D)(2). 

§ 125.86 As an owner or operator of a new facility, what must I collect and submit 

when I apply for my new or reissued NPDES permit? 

 (a) * * * 

 (1) * * * 

 (ii) The Track I requirements for new facilities that withdraw greater than 2 

mgd and less than 10 mgd in Sec. 125.84(c); 

* * * * * 

 (b) * * * 

 (3) Source waterbody flow information. You must submit to the Director the 

following information to demonstrate that your cooling water intake structure meets the 

flow requirements in Sec. 125.84(b)(3) or (c)(2). 

* * * * * 

 (4) * * * 

 (iii) The owner or operator of a new facility required to install design and 

construction technologies and/or operational measures must develop a plan which 

explains the technologies and measures selected; this plan shall be based on information 

collected for the Source Water Biological Baseline Characterization required by 40 CFR 

122.21(r)(4). Examples of appropriate technologies include, but are not limited to, 

wedgewire screens, fine mesh screens, fish handling and return systems, barrier nets, 

aquatic filter barrier systems, etc. Examples of appropriate operational measures include, 
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but are not limited to, seasonal shutdowns or reductions in flow, and continuous 

operations of screens, etc. The plan must contain the following information: 

* * * * * 

7. Section 125.87 is amended by revising paragraphs (a) introductory text and (a)(2) to 

read as follows: 

§ 125.87 As an owner or operator of a new facility, must I perform monitoring? 

* * * * * 

 (a) Biological monitoring. You must monitor both impingement and 

entrainment of the commercial, recreational, and forage base fish and shellfish species 

identified in either the Source Water Baseline Biological Characterization data required 

by 40 CFR 122.21(r)(4) or the Comprehensive Demonstration Study required by Sec. 

125.86(c)(2), depending on whether you chose to comply with Track I or Track II. The 

monitoring methods used must be consistent with those used for the Source Water 

Baseline Biological Characterization data required in 40 CFR 122.21(r)(4) or the 

Comprehensive Demonstration Study required by Sec. 125.86(c)(2). You must follow the 

monitoring frequencies identified below for at least two (2) years after the initial permit 

issuance. After that time, the Director may approve a request for less frequent sampling 

in the remaining years of the permit term and when the permit is reissued, if the Director 

determines the supporting data show that less frequent monitoring would still allow for 

the detection of any seasonal and daily variations in the species and numbers of 

individuals that are impinged or entrained. 

* * * * * 
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 (2) Entrainment sampling. You must collect samples at least biweekly to 

monitor entrainment rates (simple enumeration) for each species over a 24-hour period 

during the primary period of reproduction, larval recruitment, and peak abundance 

identified during the Source Water Baseline Biological Characterization required by 40 

CFR 122.21(r)(4) or the Comprehensive Demonstration Study required in Sec. 

125.86(c)(2). You must collect samples only when the cooling water intake structure is in 

operation. 

* * * * * 

8. Section 125.89 is amended by revising paragraphthe introductory text of paragraphs 

(a), (b)(1)(i) and (ii) to read as follows: 

§ 125.89 As the Director, what must I do to comply with the requirements of this 

subpart? 

 (a) Permit application. As the Director, you must review materials submitted by 

the applicant under 40 CFR 122.21(r)(4) and § 125.86 at the time of the initial permit 

application and before each permit renewal or reissuance. 

* * * * * 

 (b) * * * 

 (1) * * * 

 (i) If an owner or operator of a facility chooses Track I, you must review the 

Design and Construction Technology Plan required in Sec. 125.86(b)(4) to evaluate the 

suitability and feasibility of the technology proposed to minimize impingement mortality 

and entrainment of all life stages of fish and shellfish. In the first permit issued, you must 
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put a condition requiring the facility to reduce impingement mortality and entrainment 

commensurate with the implementation of the technologies in the permit. Under 

subsequent permits, the Director must review the performance of the technologies 

implemented and require additional or different design and construction technologies, if 

needed to minimize impingement mortality and entrainment of all life stages of fish and 

shellfish. In addition, you must consider whether more stringent conditions are 

reasonably necessary in accordance with Sec. 125.84(e). 

 (ii) If an owner or operator of a facility chooses Track II, you must review the 

information submitted with the Comprehensive Demonstration Study required in Sec. 

125.86(c)(2) and evaluate the suitability of the proposed design and construction 

technologies and operational measures to determine whether they will reduce both 

impingement mortality and entrainment of all life stages of fish and shellfish to 90 

percent or greater of the reduction that could be achieved through Track I. In addition, 

you must review the Verification Monitoring Plan in Sec. 125.86(c)(2)(iv)(D) and require 

that the proposed monitoring begin at the start of operations of the cooling water intake 

structure and continue for a sufficient period of time to demonstrate that the technologies 

and operational measures meet the requirements in Sec. 125.84(d)(1). Under subsequent 

permits, the Director must review the performance of the additional and/or different 

technologies or measures used and determine that they reduce the level of adverse 

environmental impact from the cooling water intake structures to a comparable level that 

the facility would achieve were it to implement the requirements of Sec. 125.84(b)(1) and 

(2). 
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* * * * * 

9. Section 125.90 is amended as follows:The suspension of 40 CFR 125.90(a), (c) and 

(d), and 125.91 through 125.99, published on July 9, 2007 (72 FR 37109) is lifted.

 a. The suspension of (a) through (c) published on July 9, 2007 (72 FR 37109) is 

lifted. 

 b. Remove and reserve paragraph (d). 

10. The suspension of 40 CFR 125.91 through 125.99, published on July 9, 2007 (72 FR 

37109) is lifted. 

11.10. Subpart J to part 125 is revised to read as follows: 

Subpart J--Requirements Applicable to Cooling Water Intake Structures for 

Existing Facilities Under Section 316(b) of the Clean Water Act 

Sec. 

125.90 Purpose of this subpart. 

125.91 Applicability. 

125.92 Special definitions. 

125.93 [Reserved.] 

125.94 As an owner or operator of an existing facility, what must I do to comply with this 

subpart? 

125.95 Permit application and supporting information requirements. 

125.96 Monitoring requirements. 

125.97 Other permit reporting and recordkeeping requirements. 

125.98 Director requirements. 
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125.99 [Reserved.] 

Subpart J--Requirements Applicable to Cooling Water Intake Structures for 

Existing Facilities Under Section 316(b) of the Clean Water Act 

§ 125.90 Purpose of this subpart. 

 (a) This subpart establishes the section 316(b) requirements that apply to 

cooling water intake structures at existing facilities that are subject to this subpart. These 

requirements include a number of components. These include standards for minimizing 

adverse environmental impact associated with the use of cooling water intake structures 

and required procedures (e.g., permit application requirements, information submission 

requirements) for establishing the appropriate technology requirements at certain 

specified facilities as well as required monitoring, reporting, and recordkeeping 

requirements to demonstrate compliance. In combination, these components represent the 

best technology available for minimizing adverse environmental impact associated with 

the use of cooling water intake structures at existing facilities. These requirements are to 

be established and implemented in National Pollutant Discharge Elimination System 

(NPDES) permits issued under authority of sections 301, 308, and 402 of the Clean 

Water Act (CWA). 

 (b) Cooling water intake structures not subject to requirements under § 125.94, 

et seq. of this Subpart or, Subpart I, or Subpart N of this part must meet requirements 

under section 316(b) of the CWA established by the Director on a case-by-case, best 

professional judgment (BPJ) basis. 
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 (c) Nothing in this subpart shall be construed to preclude or deny the right under 

section 510 of the CWA of any State or political subdivision of a State or any interstate 

agency under section 510 of the CWA to adopt or enforce any requirement with respect 

to control or abatement of pollution that is more stringent than those required by Federal 

law. 

 [NOTE: This regulation does not authorize take, as defined by the Endangered 

Species Act, 16 USC 1532(19). The U.S. Fish and Wildlife Service and National Marine 

Fisheries Service have determined that any impingement (including entrapment) or 

entrainment of Federally-listed species constitutes take. Such take may be authorized 

pursuant to the conditions of a permit issued under 16 U.S.C. 1539(a) or where consistent 

with an Incidental Take Statement contained in a Biological Opinion pursuant to 16 

U.S.C. 1536(o).] 

§ 125.91 Applicability. 

 (a) The owner or operator of an existing facility, as defined in § 125.92,(k), is 

subject to the requirements at 125.94 et seq. of this subpart if: 

 (1) The facility is a point source; 

 (2) The facility uses or proposes to use one or more cooling water intake 

structures with a cumulative design intake flow (DIF) of greater than 2 million gallons 

per day (mgd) to withdraw water from waters of the United States; and 

 (3) Twenty-five percent or more of the water the facility withdraws on an actual 

intake flow basis is used exclusively for cooling purposes. 
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 (b) Use of a cooling water intake structure includes obtaining cooling water by 

any sort of 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 subparts I or J of this part, except as 

provided in paragraphs (c) and (d) of this section. An owner or operator of an existing 

facility may not circumvent these requirements by creating arrangements to receive 

cooling water from an entity that is not itself a facility subject to subparts I or J of this 

part. 

 (c) Obtaining cooling water from a public water system, using reclaimed water 

from wastewater treatment facilities or desalination plants, or recycling treated process 

wastewater effluent as cooling water does not constitute use of a cooling water intake 

structure for purposes of this subpart. The owner or operator of a facility using reclaimed 

water and discharging it must meet the effluent limitation standards that would have 

applied to the facility from which the reclaimed water is obtained.

 (d) This subpart does not apply to offshore seafood processing facilities, 

offshore liquefied natural gas terminals, and offshore oil and gas extraction facilities that 

are existing facilities as defined in § 125.92.(k). The owners and operators of such 

facilities must meet requirements established by the Director on a case-by-case, best 

professional judgment (BPJ) basis. 

§ 125.92 Special definitions. 

 In addition to the definitions provided in 40 CFR 122.2 of this chapter, the 

following special definitions apply to this subpart: 
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(a) Actual Intake Flow (AIF) means the average volume of water withdrawn on 

an annual basis by the cooling water intake structures over the past three years. After 

[INSERT DATEdate 5 YEARS AFTER EFFECTIVE DATEyears after effective 

date of the final rule], Actual Intake Flow means the average volume of water 

withdrawn on an annual basis by the cooling water intake structures over the previous 

five years. Actual intake flow is measured at a location within the cooling water intake 

structure that the Director deems appropriate. The calculation of actual intake flow 

includes days of zero flow. AIF does not include flows associated with emergency and 

fire suppression capacity. 

(b) All life stages of fish and shellfish means eggs, larvae, juveniles, and adults. 

It does not include members of the infraclass Cirripedia in the subphylum Crustacea 

(barnacles), green mussels (Perna viridis), or zebra mussels (Dreissena polymorpha). 

The Director may determine that all life stages of fish and shellfish does not include other 

specified nuisance species. 

(c) Closed-cycle recirculating system means a system designed and properly 

operated using minimized make-up and blowdown flows that withdraws water withdrawn 

from a natural or other water sourceof the United States to support contact or 

noncontactnon-contact cooling uses within a facility, or a system designed to include 

certain impoundments that are not themselves a waters of the United States. A closedcycle recirculating system passes cooling water through the condenser and other 

components of the cooling system and reuses the water for cooling multiple times. A 

closed
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 (1) Closed-cycle recirculating system may includeincludes a facility with wet, 

dry, or dryhybrid cooling towers, a system of impoundments that are not waters of the 

United States, or any combination thereof. A properly operated and maintained closedcycle recirculating system withdraws new source water (make-up 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 Director may determine a cooling system is a closed-cycle recirculating system if the 

facility demonstrates to the satisfaction of the Director that make-up water withdrawals 

attributed specifically to the cooling portion of the cooling system have been minimized.

In the case of a facility that uses make-up water from a freshwater source, a closed-cycle 

recirculating system can generally be found to minimize make-up 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. In the case of a facility that uses make-up water from a saltwater, brackish, or other 

source with a salinity of greater than 0.5 parts per thousand, a closed-cycle recirculating 

system can generally be found to minimize make-up and blowdown flows if it reduces 

actual intake flows (AIF) by 94.9 percent as compared to a once-through cooling system 

or if its cooling tower is operated at a minimum cycles of concentration of 1.5.

 (2) Closed-cycle recirculating system also includes a system with 

impoundments of waters of the U.S. where the impoundment was constructed prior to 

[INSERT effective date of the final rule] and created for the purpose of serving as part 
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of the cooling water system as documented in the project purpose statement for any 

required Clean Water Act section 404 permit obtained to construct the impoundment. In 

the case of an impoundment whose construction pre-dated the CWA requirement to 

obtain a section 404 permit, documentation of the project’s purpose must be 

demonstrated to the satisfaction of the Director. This documentation could be some other 

license or permit obtained to lawfully construct the impoundment for the purposes of a 

cooling water system, or other such evidence as the Director finds necessary. For 

impoundments constructed in uplands or not in waters of the United States, no 

documentation of a section 404 or other permit is required. 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 

Director may determine a cooling system is a closed-cycle recirculating system if the 

facility demonstrates to the satisfaction of the Director that make-up water withdrawals 

attributed specifically to the cooling portion of the cooling system have been minimized. 

 (d) Contact cooling water means water used for cooling which comes into 

direct contact with any raw material, product, or byproduct. Examples of contact cooling 

water may include but are not limited to quench water at iron and steel plantsfacilities, 

cooling water in a cracking unit, and cooling water directly added to food and agricultural 

products processing. 

(e) Cooling water means water used for contact or noncontactnon-contact

cooling, including water used for equipment cooling, evaporative cooling tower makeup, 

and dilution of effluent heat content. The intended use of the cooling water is to absorb 
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waste heat rejected from the process or processes used, or from auxiliary operations on 

the facility’s premises. 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 in 40 CFR§ 125.91(a)(3). 

(f) Cooling water intake structure means the total physical structure and any 

associated constructed waterways used to withdraw cooling water from waters of the 

United States. The cooling water intake structure extends from the point at which water is 

first withdrawn from waters of the surface water sourceUnited States up to, and including 

the intake pumps. 

(g) Design intake flow (DIF) means the value assigned during the cooling water 

intake structure design to the maximum instantaneous rate of flow of water the cooling 

water intake system is capable of withdrawing from a source waterbody. The 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. DIF 

does not include values associated with emergency and fire suppression capacity or 

redundant pumps (i.e., back-up pumps). 

Emergency purposes means to supply backup power resources during a crisis, 

natural catastrophe, extreme weather event, or when regular systems fail unexpectedly. 
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Emergency purposes does not include situations of high or peak electricity demand, or 

regular, frequent or seasonal generation of power. 

 (h) Entrainment means any life stages of fish and shellfish in the 

intake water flow entering and passing through a cooling water intake structure and into a 

cooling water system, including the condenser or heat exchanger. Entrainable organisms 

include any organisms potentially subject to entrainment. For purposes of this subpart, 

entrainment excludes those organisms that are collected or retained by a sieve with 

maximum opening dimension of 0.56 inches. Examples of sieves meeting this definition 

include but are not limited to a 3/8 inch square mesh, or a 1⁄2 by 1⁄4 inch mesh. A facility 

must use the same mesh size when counting entrainment as is used when counting 

impingement. 

(i) Entrainment mortality means death as a result of entrainment through the 

cooling water intake structure, or death as a result of exclusion from the cooling water 

intake structure by fine mesh screens or other protective devices intended to prevent the 

passage of entrainable organisms through the cooling water intake structure. 

(j) Entrapment means the condition where impingeable fish and shellfish lack 

the means to escape the cooling water intake. Entrapment includes but is not limited to: 

organisms caught in the bucket of a traveling screen and unable to reach a fish return; 

organisms caught in the forebay of a cooling water intake system without any means of 

being returned to the source waterbody without experiencing mortality; or cooling water 

intake systems where the velocities in the intake pipes or in any channels leading to the 
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forebay prevent organisms from being able to return to the source waterbody through the 

intake pipe or channel. 

(k) Existing facility means any facility that commenced construction as 

described in 40 CFR 122.29(b)(4) on or before January 17, 2002 (or July 17, 2006 for an 

offshore oil and gas extraction facility) and any modification of, or any addition of a unit 

at such a facility. A facility built adjacent to another facility would be a new facility 

while the original facility would remain as an exiting facility for purposes of this subpart. 

A facility cannot both be an existing facility and a new facility as defined at § 125.83. 

(l) Flow reduction means any modification to a cooling water intake structure or 

its operation that serves to reduce the volume of cooling water withdrawn. Examples 

include, but are not limited to, 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. 

(m) Fragile species means those species of fish and shellfish that are least likely 

to survive any form of impingement. For purposes of this subpart, fragile species are 

defined as those with an impingement survival rate of less than 30 percent, including but 

not limited to alewife, American shad, Atlantic herring, Atlantic long-finned squid, 

Atlantic menhaden, bay anchovy, blueback herring, bluefish, butterfish, gizzard shad, 

grey snapper, hickory shad, menhaden, rainbow smelt, round herring, and silver anchovy, 

and shad of the genus Alosa . 

High energy efficiency units means any unit that has a heat rate of 7000 

Btu/KWhnet higher heating value (HHV) basis or less, or has a thermal efficiency of 
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49% HHV basis or more. The thermal efficiency shall be calculated using the EPA 

[CHP] Total System Efficiency Metric. 

 (n) Impingement means the entrapment of any life stages of fish and 

shellfish on the outer part of an intake structure or against a screening device during 

periods of intake water withdrawal. For purposes of this subpart, impingement includes 

those organisms collected or retained on a sieve with maximum distance in the opening 

of 0.56 inches, and excludes those organisms that pass through the sieve. Examples of 

sieves meeting this definition include but are not limited to a 3/8 inch square mesh, or a 

1⁄2 by 1⁄4 inch mesh. This definition is intended to prevent the conversion of entrainable 

organisms to counts of impingement or impingement mortality. The owner or operator of 

a facility must use a sieve with the same mesh size when counting entrainment as is used 

when counting impingement. 

(o) Impingement mortality (IM) means death as a result of impingement or 

entrapment. Impingement mortality also includes organisms removed from their natural 

ecosystem and lacking the ability to escape the cooling water intake system, and thus 

subject to inevitable mortality. 

(p) Independent supplier means an entity, other than the regulated facility, that 

owns and operates its own cooling water intake structure and directly withdraws water 

from waters of the United States. The supplier provides the cooling water to other 

facilities for their use, but may itself also use a portion of the water. An entity that 

provides potable water to residential populations (e.g., public water system) is not a 

supplier for purposes of this subpart. 
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(q) Latent mortality 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. 

(r) Minimize means to reduce to the smallest amount, extent, or degree 

reasonably possible. 

(s) Modified traveling screen means a traveling water screen that incorporates 

measures protective of fish and shellfish, including but not limited to: screens with 

collection buckets or equivalent mechanisms designed to minimize turbulence to aquatic 

life; addition of a guard rail or barrier to prevent loss of fish from the collection system; 

replacement of screen panel materials with smooth woven mesh, drilled mesh, molded 

mesh, or similar materials that protect fish from descaling and other abrasive injury; 

continuous or near-continuous rotation of screens and operation of fish collection 

equipment to ensure any impinged organisms are recovered as soon as practical; a low 

pressure wash or gentle vacuum to remove fish prior to any high pressure spray to 

remove debris from the screens; and 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 re-impingement of the fish, or require a large vertical drop. The 

Director may approve of fish being returned to water sources other than the original 

source water., taking into account any recommendations from the Services with respect to 

endangered or threatened species. Examples of modified traveling screens include, but 
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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. 

(t) Moribund means dying; close to death. 

(u) New unit means addition of any operatinga new “stand-alone” unit at an 

existing facility where the construction of the new unit begins after [INSERT effective 

date of the final rule],] and that does not otherwise meet the definition of a new facility 

at § 125.83. New unit includes addition or is not otherwise already subject to Subpart I of 

any electric generatingthat section. A stand-alone unit that is a stand-aloneseparate unit 

constructed at an existing that is added to a facility. For purposes of this subpart, for 

either the same general industrial operation or another purpose. A new unit also includes 

any rebuilt, repowered or replacement electric generating unit where the turbine and 

condensermay have been replaced as part of the rebuilding, repowering or replacing, 

except in the case of high energy efficiency units. If the turbine and condenser are 

replaced at separate times after [INSERT effective date of the final rule], replacement 

of the second component is when the unit becomes a new unit under this definition. New 

unit also means any newly built production units or replacement production units where 

the majority of the waste heat-producing equipment that serves as sources of noncontactits own dedicated cooling water and the majority of the heat exchanging 

equipment that contributes heat to the non-contactintake structure, or the new unit may 

use an existing or modified cooling water are newly installed or replaced.intake structure. 

(v) Offshore velocity cap means a velocity cap located a minimum of 850800

feet from the shoreline and outside of the littoral zone.. A velocity cap is an open intake 
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designed to change the direction of water withdrawwithdrawal from vertical to 

horizontal, thereby creating horizontal velocity patterns that result in avoidance of the 

intake by fish and other aquatic organisms. For purposes of this subpart, the velocity cap 

must use bar screens or otherwise exclude marine mammals, sea turtles, and other large 

aquatic organisms. 

(w) Operational measure means a modification to any operation that serves to 

minimize impact to all life stages of fish and shellfish from the cooling water intake 

structure. Examples of operational measures include, but are not limited to, more 

frequent rotation of traveling screens, use of a low pressure wash to remove fish prior to 

any high pressure spray to remove debris, maintaining adequate volume of water in a fish 

return, and debris minimization measures such as air sparging of intake screens and/or 

other measures taken to maintain the design intake velocity. 

(x) Social benefits means the increase in social welfare that results from taking 

an action. Social benefits include private benefits and those benefits not taken into 

consideration by private decision makers in the actions they choose to take, including 

effects occurring in the future. Benefits valuation involves measuring the positive aspects 

of the actions taken, in monetary terms. The principle of willingness-to-pay 

(WTP)physical and biological effects on the environment from the actions taken. Benefits 

are generally treated one or more of three ways: a narrative containing a qualitative 

discussion of environmental effects, a quantified analysis expressed in physical or 

biological units, and a monetized benefits analysis in which dollar values are applied to 

quantified physical or biological units. The dollar values in a social benefits analysis are 
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based on the principle of willingness-to-pay (WTP), which captures monetary benefits by 

measuring what individuals are willing to forgo in order to enjoy a particular benefit.

Willingness-to-pay for nonuse values can be measured using benefits transfer or a stated 

preference survey.

(y) Social costs means costs estimated from the viewpoint of society, rather 

than individual stakeholders. Social cost represents the total burden imposed on the 

economy; it is the sum of all opportunity costs incurred associated with taking actions. 

These opportunity costs consist of the value lost to society of all the goods and services 

that will not be produced and consumed as a facility complies with permit requirements, 

and society reallocates resources away from other production activities and towards 

minimizing adverse environmental impacts. 

§ 125.93 Reserved. 

§ 125.94 As an owner or operator of an existing facility, what must I do to comply 

with this subpart? 

 (a) Applicable Best Technology Available for Minimizing Adverse 

Environmental Impact (BTA) standards. 

 (1) After December 31, 2016,On or after [INSERT effective date of final 

rule], the owner or operator of an existing facility with a cumulative design intake flow 

(DIF) greater than 2 mgd is subject to the BTA (best technology available) standards for 

impingement mortality standard under paragraph (c)), and the entrainment standard under 

paragraph (d) including any measures to protect Federally-listed threatened and 
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endangered species and designated critical habitat established under paragraph (g) of this 

section. 

 (2) Prior to December 31, 2016,[INSERT effective date of final rule], the 

owner or operator of an existing facility with a cumulative design intake flow (DIF) 

greater than 2 mgd is subject to site-specific impingement mortality and entrainment 

requirements as determined by the Director on a case-by-case Best Professional 

Judgment basis. The Director’s BTA determination may be based on consideration of 

some or all of the factors at § 125.98 (f)(2) and (3) and BTA Standard for Impingement 

Mortality atthe requirements of § 125.94(c). If the Director requires additional 

information to make the decision on what BTA requirements to include in the applicant’s 

permit for impingement mortality and entrainment, the Director should consider whether 

to require any of the information at §40 CFR 122.21(r). 

 (3) The owner or operator of a new unit at an is subject to the impingement 

mortality and entrainment standards under paragraph (e) for all cooling water intake 

flows used by the new unit. The remainder of the existing facility with a cumulative 

design intake flow (DIF) greater than 2 mgd is subject to the impingement mortality 

standard under paragraph (c)), and the entrainment standard under paragraph (ed) of this 

section. The entire existing facility including any new units is subject to any measures to 

protect Federally-listed threatened and endangered species and designated critical habitat 

established under paragraph (g) of this section.

 (b) Compliance with BTA standards.
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 (1) Aligning compliance deadlines for impingement mortality and entrainment 

requirements. (b) Compliance with BTA standards.

 (1) Aligning compliance deadlines for impingement mortality and entrainment 

requirements. After issuance of a final permit that establishes the entrainment 

requirements under § 125.94 (d), the owner or operator of an existing facility must 

comply with the impingement mortality standard in paragraph § 125.94 (c) as soon as 

practicable. The Director may establish interim compliance milestones in the permit.

possible. The Director may establish interim compliance milestones in the permit.

 (2) After issuance of a final permit establishing the entrainment requirements 

under § 125.94 (d), the owner or operator of an existing facility must comply with the 

entrainment standard as soon as possiblepracticable, based on a schedule of requirements 

established by the Director. The Director may establish interim compliance milestones in 

the permit.

 The Director may establish interim compliance milestones in the permit.

 (3) The owner or operator of a new unit at an existing facility must comply with 

the BTA standards in paragraphsat § 125.94 (c) and (e) with respect to the new unit upon 

commencement of the new unit’s operation.

 (c) BTA Standards for Impingement Mortality. 

 (c) BTA Standards for Impingement Mortality. The owner or operator of an 

existing facility or new unit at an existing facility must comply with one of the 

alternatives in (c)(1) through (c)(7) below, except as provided in (c)(10),11) or (c)(12) or 

(c)(13), when approved by the Director. Additionally, facilities In addition, a facility 
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may also be subject to the requirements of (c)(8), (c)(9), or (c)(11g) of this section asif

the Director determines applicable.requires such additional measures. 

 (1) Closed-cycle recirculating system. A facility must operate a closed-cycle 

recirculating system as defined at § 125.92.(c). In addition, you must monitor yourthe

actual intake flows at a minimum frequency of daily. YourThe monitoring must be 

representative of normal operating conditions, and must include measuring cooling water 

withdrawals, make-up water, and blow down volume. In lieu of daily intake flow 

monitoring, you may monitor your cycles of concentration at a minimum frequency of 

daily; or 

 (2) 0.5 Feet Per Second Through-Screen Design Velocity. A facility must 

operate a cooling water intake structure that has a maximum design through-screen intake 

velocity of 0.5 feet per second. The owner or operator of the facility must submit 

information to the Director that demonstrates that the maximum design intake velocity as 

water passes through the structural components of a screen measured perpendicular to the 

screen mesh does not exceed 0.5 feet per second. The maximum velocity limit must be 

achieved under all conditions, including during minimum ambient source water surface 

elevations (based on BPJ using hydrological data) and during periods of maximum head 

loss across the screens or other devices during normal operation of the intake structure; or 

 (3) 0.5 Feet Per Second Through-Screen Actual Velocity. A facility must 

operate a cooling water intake structure that has a maximum through-screen intake 

velocity of 0.5 feet per second. The owner or operator of the facility must submit 

information to the Director that demonstrates that the maximum intake velocity as water 
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passes through the structural components of a screen measured perpendicular to the 

screen mesh does not exceed 0.5 feet per second. The maximum velocity limit must be 

achieved under all conditions, including during minimum ambient source water surface 

elevations (based on best professional judgment using hydrological data) and during 

periods of maximum head loss across the screens or other devices during normal 

operation of the intake structure. The Director may authorize the owner or operator of the 

facility to exceed the 0.5 fps velocity standard at an intake for brief periods for the 

purpose of maintaining the cooling water intake system, such as backwashing the screen 

face. If the intake does not have a screen, the maximum intake velocity perpendicular to 

the opening of the intake must not exceed 0.5 feet per second during minimum ambient 

source water surface elevations. In addition, you must monitor yourthe velocity at the 

screen at a minimum frequency of daily. In lieu of velocity monitoring at the screen face, 

you may calculate the through-screen velocity using water flow, water depth, and the 

screen open areas; or 

 (4) Existing offshore velocity cap. A facility must operate an existing offshore 

velocity cap as defined at § 125.92(v) that was installed prior toon or before [INSERT 

effective date of rule]. Offshore velocity caps installed after [INSERT effective date of 

rule] must make either a demonstration under paragraph (6) or meet the performance 

standard under paragraph (7). In addition, you must monitor your intake flow at a 

minimum frequency of daily; or

 (5) Modified traveling screens. A facility must operate a modified traveling 

screen that the Director determines meets the definition at § 125.92(s) and that, after 
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review of the information required in the impingement technology performance 

optimization study at 40 CFR 122.21(r)(6)(i), the Director determines is the best 

technology available for impingement reduction at the site. As the basis for the Director’s 

determination, the owner or operator of the facility must demonstrate the technology has 

beenis or will be optimized to minimize impingement mortality of all non-fragile species. 

The Director must include verifiable and enforceable permit conditions that ensure the 

technology will perform as demonstrated; or 

 (6) Systems of technologies as the BTA for impingement mortality. A facility 

must operate a system of technologies, management practices, and operational measures, 

that, after review of the information required in the impingement technology performance 

optimization study at 40 CFR 122.21(r)(6)(ii), the Director determines is the best 

technology available for impingement reduction at your cooling water intake structures. 

As the basis for the Director’s determination, the owner or operator of the facility must 

demonstrate the system of technology has been optimized to minimize impingement 

mortality of all non-fragile species. In addition, the Director’s decision will be informed 

by comparing the impingement mortality performance data under 40 CFR 

122.21(r)(6)(ii)(D) to the impingement mortality performance standard that would 

otherwise apply under paragraph (7). The Director must include verifiable and 

enforceable permit conditions that ensure the system of technologies will perform as 

demonstrated; or 

 (7) Impingement mortality performance standard. A facility must achieve an 

annuala 12-month impingement mortality performance standard of all life stages of fish 
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and shellfish of no more than 2524 percent mortality, including latent mortality, for all 

non-fragile species together that are collected or retained in a sieve with maximum 

opening dimension of 0.56 inches and kept for a holding period of 18 to 96 hours. The 

Director may, however, prescribe an alternative holding period. The annual average of 

impingement mortality is calculated as the sum of total impingement mortality for the 

previous 12 months divided by the sum of total impingement for the previous 12 months. 

The owner or operator of the facility must choose whether to demonstrate compliance 

with this requirement for the entire facility, or for each individual cooling water intake 

structure for which (c)(7) is the selected impingement mortality requirement. You must 

conduct biological monitoring at a minimum frequency of monthly to demonstrate your 

impingement mortality performance. Note: the annual impingement mortality 

performance standard does not authorize take of threatened or endangered species. The 

Director may require additional measures to protect threatened and endangered species, 

as provided in (c)(8) of this section;Each month, you must use all of the monitoring data 

collected during the previous 12 months to calculate the 12-month survival percentage. 

The 12-month impingement mortality performance standard is the total number of fish 

killed divided by the total number of fish impinged over the course of the entire 12 

months. The owner or operator of the facility must choose whether to demonstrate 

compliance with this requirement for the entire facility, or for each individual cooling 

water intake structure for which (c)(7) is the selected impingement mortality requirement. 
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 (8) Additional measures to protect threatened and endangered species. The 

Director may require additional measures as best technology available to minimize 

impingement mortality if the Director determines that your compliance with applicable 

requirements of this section would not protect threatened and endangered (T&E) species. 

Nothing in this subpart authorizes the take, as defined at 16 U.S.C. 1532(19), of 

threatened or endangered wildlife. Such take is prohibited unless it is exempted pursuant 

to 16 U.S.C. 1536(o) or permitted pursuant to 16 U.S.C. 1539(a). Absent such an 

exemption or permit, any facility operating under the authority of this subpart must not 

take threatened or endangered wildlife. Through coordination with the appropriate 

National Marine Fisheries Service or United States Fish and Wildlife Service office, the 

owner or operator of an existing facility without an exemption pursuant to 16 U.S.C. 

1536(o) or permit pursuant to 16 U.S.C. 1539(a) must select and implement additional 

design and construction technologies or operational measures for minimizing 

impingement mortality of fish and shellfish, where appropriate, if: 

 (i) There are threatened or endangered or otherwise protected federal, state, or 

tribal species, or critical habitat for these species, within the hydraulic zone of influence 

of the cooling water intake structure; or 

 (ii) Based on information submitted to the Director by any fishery management 

agency or other relevant information, there are migratory or sport or commercial species 

subject to impingement that pass through the hydraulic zone of influence of the cooling 

water intake structure; or 
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 (iii) It is determined by the Director, based on information submitted by any 

fishery management agencies or other relevant information, that the facility, after 

meeting the technology-based performance requirements in § 125.94(c) of this section, 

would still contribute unacceptable stress to the protected species, or critical habitat of 

those species. 

 (9) Additional measures for shellfish. The Director may require additional 

measures, such as seasonal deployment of barrier nets, to protect shellfish. (8) 

Additional measures for shellfish. The owner or operator must comply with any 

additional measures, such as seasonal deployment of barrier nets, established by the 

Director to protect shellfish. 

 (9) Additional measures for other species. The owner or operator must comply 

with any additional measures, established by the Director, to protect fragile species. 

 (10) Reuse of other water for cooling purposes. This impingement mortality 

standard does not apply to that portion of cooling water that is process water, gray water, 

waste water, reclaimed water, or other waters reused as cooling water in lieu of water 

obtained by marine, estuarine, or freshwater intakes. 

 (11) Additional measures for fragile species. The Director may require 

additional measures to protect fragile species. 

 (12) De minimis rate of impingement. In limited circumstances, rates of 

impingement may be so exceptionally low at a facility that additional impingement 

controls may not be justified. In such circumstances, theThe Director, based on review 
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of site-specific data submitted under 40 CFR 122.21(r) and where no threatened or 

endangered species may be present,), may conclude that the documented rate of 

impingement at the cooling water intake is so low that no additional controls are 

warranted. For threatened or endangered species, all unauthorized take is prohibited by 

the Endangered Species Act of 1973 (ESA; 7 U.S.C. § 136, 16 U.S.C.16 U.S.C. § 1531 et 

seq.). Notice of a determination that no additional impingement controls are warranted 

must be included in the draft or proposed permit and the Director’s response to all 

comments on this determination must be included in the record for the final permit. 

 (1312) Low capacity utilization power generating units used only in emergency 

circumstances.. If an existing facility has a cooling water intake structure used 

exclusively for one or more existing electric generating units, each with an annual 

average capacity utilization ratingrate of less than 8 percent for each of the previous 5 

years, and the generating units are used solely for emergency purposes, as defined at § 

125.92averaged over a 24-month block contiguous period, the owner or operator may 

request that the Director establishconsider less stringent requirements for impingement 

mortality for that cooling water intake structure. The Director may, based on review of 

site-specific data concerning cooling water system data under 40 CFR 122.21(r)(5), 

establish the BTA standards for impingement mortality for that cooling water intake 

structure that are less stringent than (c)(1) tothrough (c)(7) above. This provision does not 

apply to those electric generating units run when there is a high demand or peak demand 

for electricity, such as seasonally operated peaking units. 
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 (d) BTA standards for entrainment for existing facilities. The Director must 

establish BTA standards for entrainment for each intake on a site-specific basis. These 

standards must reflect the Director’s determination of the maximum reduction in 

entrainment warranted after consideration of the relevant factors as specified in § 125.98. 

The Director may also require periodic reporting on your progress towards installation 

and operation of site-specific entrainment controls. These reports may include updates on 

planning, design, and construction or other appropriate topics as required by the Director. 

If the Director determines that the site-specific BTA standard for entrainment under this 

paragraph requires performance equivalent to a closed-cycle recirculating system as 

defined at § 125.92,(c), then under § 125.94(c)(1) your facility will comply with the 

impingement mortality standard for that intake. Nothing in this subpart authorizes the 

take, as defined at 16 U.S.C. 1532(19), of threatened or endangered wildlife. Such take is 

prohibited unless it is exempted pursuant to 16 U.S.C. 1536(o) or permitted pursuant to 

16 U.S.C. 1539(a). Absent such an exemption or permit, any facility operating under the 

authority of this subpart must not take threatened or endangered wildlife. In addition, the 

owner or operator of an existing facility must select and implement design and 

construction technologies or operational measures for minimizing entrainment of 

entrainable life stages of fish and shellfish if: 

 (i) There are threatened or endangered or otherwise protected federal, state, or 

tribal species, or critical habitat for these species, within the hydraulic zone of influence 

of the cooling water intake structure; or 
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 (ii) Based on information submitted by any fishery management agency or other 

relevant information, there are or would be undesirable cumulative stressors affecting 

entrainable life stages of species and the Director determines that the facility, after 

meeting the entrainment standard of this section, would still contribute unacceptable 

stress to the protected species, or critical habitat of those species. 

 (e) BTA standards for impingement mortality and entrainment for new units at 

existing facilities. The owner or operator of a new unit at an existing facility must achieve 

the impingement mortality and entrainment standards provided in either paragraph (e)(1) 

or (e)(2) of this section, except as provided in paragraph (e)(34) of this section, for each 

cooling water intake structure used to provide cooling water to the new unit. 

 (1) Requirements for new units. The owner or operator of athe 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 for the new unit. 

 (2) Alternative requirements for new units. The owner or operator of a new unit 

at an existing facility must demonstrate to the Director that it will operate and maintain 

the technologies for the intake flow serving the new unit that and operational measures 

employed will reduce the level of adverse environmental impact from any cooling water 

intake structure used to supply cooling water to the new unit to a comparable level to that 

which would be achieved under § 125.94(e)(1). This demonstration must include a 

showing that the entrainment of all stages of fish and shellfish that pass a sieve with a 

maximum opening dimension of 0.56 inches. The owner or operator of a facility must 
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demonstrate entrainment reductionsreduction is equivalent to 90 percent or greater of the 

reduction that could be achieved through compliance with paragraph § 125.94(e)(1) of). 

In addition this section.demonstration must include a showing that the impacts to fish and 

shellfish, including important forage and predator species, within the watershed will be 

comparable to those which would result under the requirements of § 125.94(e)(1). 

 (3) This standard does not apply to: 

 (i) Process water, gray water, waste water, reclaimed water, or other waters 

reused as cooling water in lieu of water obtained by marine, estuarine, or freshwater 

intakes; 

 (ii) Cooling water used by manufacturing facilities for contact cooling purposes; 

 (iii) Portions of those water withdrawals for auxiliary plant cooling uses 

comprising less than two mgd of the facility’s flow; and 

 (iv) Any quantity of emergency back-up water flows. 

 (4) The Director may establish alternative requirements if the data specific to 

the facility indicate that compliance with the requirements of paragraphs (e)(1) or (2) of 

this section 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, or significant adverse impacts on local 

energy markets; 

 (i) The alternative requirements must achieve a level of performance as close as 

practicable to the requirements of paragraphs (e)(1) or (2) of this section; 
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 (ii) The alternative requirements will ensure compliance with other provisions 

of the Clean Water Act and other federal statutes, including, where applicable, the 

Endangered Species Act which prohibits the take of threatened and endangered species, 

unless it is authorized by an Incidental Take Statement (50 CFR 402.14(i)) or a Section 

10 permit (50 CFR 222.307) issued by the Fish and Wildlife Service or the National 

Marine Fisheries Service, and any applicable requirement of state law; 

 (iii) The burden is on the owner or operator of the facility requesting the 

alternative requirement to demonstrate that alternative requirements should be authorized 

for the new unit.

 (5) In addition, the (4) The owner or operator of a new unit at an existing facility 

must select and implement design and construction technologies or operational measures 

for minimizing entrainment of entrainable life stages of fish and shellfish if: 

 (i) There are threatened or endangered or otherwise protected federal, state, or 

tribal species, or critical habitat for these species, within the hydraulic zone of influence 

of the cooling water intake structure; or 

 (ii) Based on information submittedcomply with any alternative requirements 

established by any fishery management agency or other relevant information, there are or 

would be undesirable cumulative stressors affecting entrainable life stages of species and 

the Director determines that the facility, after meeting the entrainment standard of this 

section, would still contribute unacceptable stresspursuant to the protected species or 

critical habitat of those species.§ 125.98(b)(7). 
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 (65) For cooling water flows excluded by paragraph (e)(3) of this section, the 

Director may establish additional BTA standards for impingement mortality and 

entrainment on a site-specific basis. 

 (f) Nuclear facilities. If the owner or operator of a nuclear facility demonstrates 

to the Director, upon the Director’s consultation with the Nuclear Regulatory 

Commission, the Department of Energy, or the Naval Nuclear Propulsion Program, that 

compliance with this subpart would result in a conflict with a safety requirement 

established by the Commission, the Department, or the Program, the Director must make 

a site-specific determination of best technology available for minimizing adverse 

environmental impact that would not result in a conflict with the Commission’s, the 

Department’s, or the Program’s safety requirement. 

 (g (g) Additional measures to protect Federally-listed threatened and 

endangered species and designated critical habitat. The Director may establish in the 

permit additional control measures, monitoring requirements, and reporting requirements 

that are designed to minimize incidental take, reduce or remove more than minor 

detrimental effects to Federally-listed species and designated critical habitat, or avoid 

jeopardizing Federally-listed species or destroying or adversely modifying designated 

critical habitat (e.g., prey base). Such control measures, monitoring requirements, and 

reporting requirements may include measures or requirements identified by an 

appropriate Field Office of the U.S. Fish and Wildlife Service and/or Regional Office of 

the National Marine Fisheries Service during the 60 day review period pursuant to § 

125.98(h) or the public notice and comment period pursuant to 40 CFR 124.10. Where 
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established in the permit by the Director, the owner or operator must implement any such 

requirements. 

 (h) Interim BTA requirements. An owner or operator of a facility may be subject 

to interim BTA requirements established by the Director in the permit on a site-specific 

basis. 

 (hi) More stringent standards. The Director must establish more stringent 

requirements as best technology available for minimizing adverse environmental impact 

if the Director determines that your compliance with the applicable requirements of this 

section would not meet the requirements of applicable State or Tribal law, including 

compliance with applicable water quality standards (including designated uses, criteria, 

and antidegradation requirements), Tribal law, or other Federal law (including but not 

limited to the Endangered Species Act, Marine Mammal Protection Act, Coastal Zone 

Management Act, and the Magnuson-Stevens Fishery Conservation and Management 

Act).). (j) The owner or operator of a facility subject to this subpart must:

 (i) The owner or operator of a facility subject to this subpart must: 

 (1) Submit and retain permit application and supporting information as 

specified in § 125.95; 

 (2) Conduct compliance monitoring as specified in § 125.96; and 

 (3) Report information and data and keep records as specified in § 125.97. 

§ 125.95 Permit application and supporting information requirements. 

(a) Permit application submittal timeframe for existing facilities. 
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(1) The owner or operator of a facility subject to this subpart applying for 

reissuance of awhose currently effective permit expiringexpires after December 31, 

2016,[INSERT date 45 months after effective date of the final rule], must submit to 

the Director the information required in the applicable provisions of 40 CFR 122.21(r) to 

the Director no later than 180 days before the current permit expires.when applying for a 

subsequent permit (consistent with the owner or operator’s duty to reapply pursuant to 40 

CFR 122.21(d)).

(2) The owner or operator of a facility subject to this subpart applying for 

reissuance of a whose currently effective permit expiringexpires prior to or on December 

31, 2016,[INSERT date 45 months after effective date of the final rule], may request 

the Director to establish an alternate schedule for the submission of the information 

required in 40 CFR 122.21(r).) when applying for a subsequent permit (consistent with 

the owner or operator’s duty to reapply pursuant to 40 CFR 122.21(d)). If the owner or 

operator of the facility demonstrates that it could not develop the required information by 

the applicable date for submission, the Director must establish an alternate schedule for 

submission of the required information. 

(3) The Director may 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.

If the manmade lake or reservoir contains Federally-listed threatened and endangered 

species, or is designated critical habitat, such a waiver shall not be granted.
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 (b) Permit application submittal timeframe for new units. For the owner or 

operator of any new unit at an existing facility subject to this subpart: 

 (1) If you choose to comply withYou must submit the entrainment standards 

under § 125.94(e)(1), you must update the information required in 40 CFR 122.21(r)(2), 

(r)(3), (r)(4), (r)(5), applicable provisions of (r)(6), and (r)(8) specific to) for the new unit

and must submit to the Director no later than 180 days before the planned 

commencement of cooling water withdrawals for the operation of the new unit. If you 

have already submitted the required information in your previous permit application, you 

may choose to submit an update to the required information.

 (2) If you choose to comply with the entrainment standards under § 

125.94(e)(2), you must submit 40 CFR 122.21(r)(9) to (r)(13) no later than 180 days 

before the planned commencement of cooling water withdrawals for the operation of the 

new unit. 

 (c) Subsequent permit applications. (2) The owner or operator is encouraged 

to submit their permit applications well in advance of the 180 day requirement to avoid 

delay. 

 (c) Permit applications. After the initial submission of the 40 CFR 122.21(r) 

permit application studies after [INSERT effective date of final rule], 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 current source water, intake structure, 
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cooling water system, and operating conditions. AnyAny habitat designated as critical or

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 potential for a substantial change that must be addressed by the 

owner/operator in subsequent permit applications, unless the facility received an 

exemption pursuant to 16 U.S.C. 1536(o) or permitteda permit pursuant to 16 U.S.C. 

1539(a) or it was determined that there is no reasonable expectation of take. The owner or 

operator of a facility must submit its request for reduced cooling water intake structure 

and waterbody application information to the Director at least two years and six months 

prior to the expiration of its NPDES permit. The owner or operator’s request must 

identify each element in this subsection that it determines has not substantially changed 

since the previous permit application and the basis for the determination. The Director 

has the discretion to accept or reject any part of the request. 

 (d) The Director has the discretion to request additional information to 

supplement the permit application process, including inspection of thea request to inspect 

a facility. 

 (e) Permit application records. The owner or operator of a facility must keep 

records of all submissions that are part of its permit application until the subsequent 

permit is issued to document compliance with the requirements of this section. If the 

Director approves a request for reduced permit application studies under § 125.95(a) or 

(c) or § 125.98(g), the owner or operator of a facility must keep records of all 
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submissions that are part of the previous permit application until the subsequent permit is 

issued. 

 (f) In addition, in developing its permit application, the owner or operator of an 

existing facility or new unit at an existing facility must, based on readily available 

information at the time of the permit application, instead of the information required at § 

122.21(r)(4)(vi) identify all Federally-listed threatened and endangered species and/or 

designated critical habitat that are or may be present in the action area. 

 (g) Certification. The owner or operator of a facility must certify that its permit 

application is true, accurate and complete pursuant to § 122.22(d). 

§ 125.96 Monitoring requirements. 

 (a) Monitoring requirements for impingement mortality for existing facilities.

The Director may establish monitoring requirements in addition to those specified at § 

125.94(c), including, for example, biological monitoring, intake velocity and flow 

measurements. If the Director establishes such monitoring, the specific protocols will be 

determined by the Director. 

(b) Monitoring requirements for entrainment for existing unitsfacilities. 

Monitoring requirements for entrainment will be determined by the Director on a sitespecific basis, as appropriate, to meet requirements under § 125.94(d). 

 (c) Additional monitoring requirements for existing unitsfacilities. The Director 

may require additional monitoring for impingement or entrainment including, but not 

limited to, the following: 
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 (1) The Director may require additional monitoring if there are changes in 

operating conditions at the facility or in the source water bodywaterbody that warrant a 

re-examination of the operational conditions identified at 40 CFR 122.21(r). 

 (2) The Director may require additional monitoring for species not subject to 

the BTA requirements for impingement mortality at § 125.95(c). Such monitoring 

requirements will be determined by the Director on a site-specific basis. 

 (d) Monitoring requirements for new units. at existing facilities. Monitoring is 

required to demonstrate compliance with the requirements of § 125.94(c) and § 

125.94(e). 

 (1) The Director may establish monitoring requirements for impingement, 

impingement mortality, and entrainment of the commercial, recreational, and forage base 

fish and shellfish species identified in addition tothe Source Water Baseline Biological 

Characterization data required by 40 CFR 122.21(r)(4). Monitoring methods used must 

be consistent with those specified at § 125.94(c), including,used for example, biological 

monitoring, intake velocity and flow measurements.the Source Water Baseline Biological 

Characterization at 40 CFR 122.21(r)(4). If the Director establishes such monitoring, the 

requirements, the frequency of monitoring and specific protocols will be determined by 

the Director. 

 (2) If your facility is subject to the requirements of § 125.94(e)(1) or (2), the 

frequency of flow monitoring and velocity monitoring must be daily and must be 

representative of normal operating conditions. Flow monitoring must include measuring 
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cooling water withdrawals, make-up water, and blowdown volume. The Director may 

require additional monitoring necessary to demonstrate compliance with § 125.94(e). 

 (3) If your facility is subject to the requirements of § 125.94(e)(2), you must 

continue to monitor to demonstrate achievement of reductions commensurate with a 

closed-cycle recirculating system. You must monitor entrainable organisms at a 

proximity to the intake that is representative of the entrainable organisms in the absence 

of the intake structure. You must also monitor the latent entrainment mortality in front of 

the intake structure. 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. Monitoring must be 

representative of the cooling water intake when the structure is in operation. In addition, 

sufficient samples must be collected to allow for calculation of annual average 

entrainment levels of all life stages of fish and shellfish. Specific monitoring protocols 

and frequency of monitoring will be determined by the Director. You 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 thea subsequent permit is 

reissued. The monitoring must measure the total count of entrainable organisms or 

density of organisms, unless the Director approves of a different metric for such 

measurements. In addition, you must monitor the AIF for each intake. The AIF must be 

measured at the same time as the samples of entrainable organisms are collected. The 
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Director may require additional monitoring necessary to demonstrate compliance with § 

125.94(e). 

 (4) The Director may require additional monitoring for impingement or 

entrainment at the cooling water intake structure used by a new unit including, but not 

limited to, the following: 

 (i) The Director may require additional monitoring if there are changes in 

operating conditions at the facility or in the source water bodywaterbody that warrant a 

re-examination of the operational conditions identified at 40 CFR 122.21(r). 

 (ii) The Director may require additional monitoring for species not subject to 

the BTA requirements for impingement mortality at § 125.95(c). Such monitoring 

requirements will be determined by the Director on a site-specific basis. 

 (e) Visual or remote inspections. You must either conduct visual inspections or 

employ remote monitoring devices during the period the cooling water intake structure is 

in operation. You must conduct such inspections at least weekly to ensure that any 

technologies operated to comply with § 125.94 are maintained and operated to function 

as designed. including those installed to protect Federally-listed threatened or endangered 

species or designated critical habitat. The Director may establish alternative procedures if 

this requirement is not feasible (e.g., an offshore intake, velocity cap, or during periods of 

inclement weather). 

 (f) Request for reduced monitoring. For facilities that are subject to § 

125.94(c)(7),) and where the facility’s cooling water intake structure does not directly or 

indirectly affect Federally-listed threatened and endangered species, or designated 
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critical habitat, the owner or operator of the facility may request the Director to 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 § 125.94(c). 

 (g) Additional monitoring related to Federally-listed threatened and endangered 

species and designated critical habitat at existing facilities. Where the Director requires 

additional measures to protect Federally-listed threatened or endangered species or 

designated critical habitat pursuant to § 125.94(g), the Director shall require monitoring 

associated with those measures. 

§ 125.97 Other permit reporting and recordkeeping requirements. 

 The owner or operator of an existing facility subject to this subpart is required 

to submit to the Director the following information: 

 (a) Monitoring reports. You must include with your Discharge Monitoring 

Reports (DMRs) (or equivalent State reports) and results of all monitoring, 

demonstrations, and other information required by yourthe permit sufficient to determine 

compliance with the permit conditions and requirements established under § 125.94. 

 (b) Status reports. You must submit any statusAny reports required by the 

Director under § 125.94(d).. 

 (c) Annual certification statement and report. You must submit anAn annual 

certification statement signed by the responsible corporate officer as defined in 40 CFR 

403.12(l) or § 122.22 subject to the following: 
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 (1) If the information contained in the previous year’s annual certification is 

still pertinent, you may simply state as such in a letter to the Director and the letter, along 

with any applicable data submission requirements specified in this section shall constitute 

the annual certification. 

 (2) If you have substantially modified operation of any unit at your facility that 

impacts cooling water withdrawals or operation of your cooling water intake structures, 

you must provide a summary of those changes in the report. In addition, you must submit 

revisions to the information required at § 122.21(r) in your next permit application.

 (d) Permit reporting records retention. your report. In addition, you must 

submit revisions to the information required at § 122.21(r) in your next permit 

application.

 (d) Permit reporting records retention. You must keep recordsRecords of all 

submissions that are part of the permit reporting requirements of this section must be 

retained until the subsequent permit is issued. In addition, the Director may require 

supplemental recordkeeping such as compliance monitoring under § 125.96, 

supplemental data collection under §40 CFR 122.21, additional monitoring or data 

collection under § 125.95. 

 (e) Reporting. The Director has the discretion to require additional 

supplemental permit reporting when necessary to establish permit compliance and may 

provide for periodic inspection of the facility. The Director may require additional 

supplemental reporting including but not limited to the records required under § 

125.97(d). 
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 (f) Records of Director’s Determination of BTA for Entrainment. You must 

keep allAll records supporting the Director’s Determination of BTA for Entrainment 

under § 125.98(f) or (g) must be retained until such time as the Director revises the 

Determination of BTA for Entrainment in yourthe permit. 

 (g) Additional reporting requirements related to Federally-listed threatened and 

endangered species or designated critical habitat. Where the Director requires additional 

measures to protect Federally-listed threatened or endangered species or critical habitat 

pursuant to § 125.94(g), the Director shall require reporting associated with those 

measures. 

§ 125.98 Director requirements. 

 (a) Permit application. The Director must review the materials submitted by the 

applicant under §40 CFR 122.21(r) for completeness pursuant to 40 CFR 122.21(e) at the 

time of initial permit application and before each permit renewal or reissuance. The 

Director may waive submission of the information at 122.21(r)(11) if the Director 

chooses not to consider benefits in relation to costs in entrainment BTA decision 

making.any application for a subsequent permit. 

(b) Permitting requirements. (b) Permitting requirements. Section 

316(b) requirements are implemented through an NPDES permit. Based on the 

information submitted in the permit application, the Director must determine the 

requirements and conditions to include in the permit. 

 (1) Such permits, including permits with alternative requirements under 

paragraph (7), must include the following language as a permit condition: “Nothing in 
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this permit authorizes take for the purposes of a facility’s compliance with the 

Endangered Species Act.” 

 (2) In the case of any permit issued after December 31, 2016,[INSERT date 45 

months after effective date of the final rule], at a minimum, the permit must include 

conditions to implement and ensure compliance with the impingement mortality standard 

at § 125.94(c) and the entrainment standard at § 125.94(d) that ), including any measures 

to protect Federally-listed threatened and endangered species and designated critical 

habitat required by the Director determines applies to the facility.. In addition, the permit 

must include conditions, management practices and operational measures necessary to 

ensure proper operation of any technology used to comply with the impingement 

mortality standard at § 125.94(c) and the entrainment standard at § 125.94(d). Pursuant 

to § 125.94(g), the permit may include additional control measures, monitoring 

requirements, and reporting requirements that are designed to minimize incidental take, 

reduce or remove more than minor detrimental effects to Federally-listed species and 

designated critical habitat, or avoid jeopardizing Federally-listed species or destroying or 

adversely modifying designated critical habitat (e.g. prey base). Such control measures, 

monitoring requirements, and reporting requirements may include measures or 

requirements identified by the U.S. Fish and Wildlife Service and/or the National Marine 

Fisheries Service during the 60 day review period pursuant to § 125.98(h) or the public 

notice and comment period pursuant to 40 CFR 124.10. The Director may include 

additional permit requirements if:
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 (2) (i) Based on information submitted to the Director by any fishery 

management agency or other relevant information, there are migratory or sport or 

commercial species subject to entrainment that may be directly or indirectly affected by 

the cooling water intake structure; or 

 (ii) It is determined by the Director, based on information submitted by any 

fishery management agencies or other relevant information, that operation of the facility, 

after meeting the entrainment standard of this section, would still result in undesirable 

cumulative stressors to Federally-listed and proposed, threatened and endangered species, 

and designated and proposed critical habitat. 

 (3) At a minimum, the permit must require the permittee to perform the 

monitoring monitor as required at § 125.94 and § 125.96. 

 (34) At a minimum, the permit must require the permittee to report and keep 

the records specified at § 125.97. 

 (45) After [INSERT effective date of the final rule], in the case of any permit 

issued before December 31, 2016[INSERT date 45 months after effective date of the 

final rule] for which the Director, pursuant to § 125.95(a)(2), has established an alternate 

schedule for submission of the information required by 40 CFR 122.21(r), the Director 

may include permit conditions to ensure that, for any subsequent permit, the Director will 

have all the information required by 40 CFR 122.21(r) necessary to establish 

impingement mortality and entrainment BTA requirements under § 125.94(c) and (d). In 

addition, the Director must establish interim BTA requirements in the permit based on the 
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Director’s best professional judgment on a site-specific basis in accordance with § 

125.90(b) and §40 CFR 401.14. 

(5 (6) In the case of any permit issued after [INSERT effective date of the 

final rule], and applied for before [INSERT effective date of the final rule], the 

Director may include permit conditions to ensure that the Director will have all the 

information under 40 CFR 122.21(r) necessary to establish impingement mortality and 

entrainment BTA requirements under § 125.94(c) and (d) for the subsequent permit. The 

Director must establish interim BTA requirements in the permit on a site-specific basis 

based on the Director’s best professional judgment on a site-specific basis in accordance 

with § 125.90(b) and §40 CFR 401.14. 

 (7) For new units at existing facilities, the Director may establish alternative 

requirements if the data specific to the facility indicate that compliance with the 

requirements of paragraphs (e)(1) or (2) of § 125.94 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, or significant adverse impacts on local energy markets: 

 (i) The alternative requirements must achieve a level of performance as close as 

practicable to the requirements of paragraph (e)(1) of § 125.94; 

 (ii) The alternative requirements must ensure compliance with these regulations, 

other provisions of the Clean Water Act, and State and Tribal law; 
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 (iii) The burden is on the owner or operator of the facility requesting the 

alternative requirement to demonstrate that alternative requirements should be authorized 

for the new unit.

 (8) The Director may require additional measures such as seasonal deployment 

of barrier nets, to protect shellfish. 

 (c) Compliance schedule. When the Director establishes a schedule of 

requirements under § 125.94(b), the schedule must provide for compliance with § 

125.94(c) and (d) as soon as possiblepracticable. When establishing a schedule for 

electric power generating facilities, the Director should consider measures to maintain 

adequate energy reliability and necessary grid reserve capacity during any facility outage. 

These may include establishing a staggered schedule for multiple facilities serving the 

same localities. The Director may confer with independent system operators and state 

public utility regulatory agencies when establishing a schedule for electric power 

generating facilities. The Director may determine that extenuating circumstances (e.g., 

lengthy scheduled outages, future production schedules) warrant establishing a different 

compliance date for any manufacturing facility. 

 (d) Supplemental Technologies and Monitoring. The Director may require 

additional technologies for protection of fragile species, and may require additional 

monitoring of species of fish and shellfish not already required under § 125.95(c). The 

Director may consider data submitted by other interested parties. The Director may also 

require additional study and monitoring if a threatened or endangered species has been 

identified in the vicinity of the intake. 
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 (e) Impingement technology performance optimization study. If theThe owner 

or operator of a facility that chooses to comply with § 125.94(c)(5) or (6), the Director 

may find that the) must demonstrate in its impingement technology performance 

optimization study does not demonstrate that the operation of its impingement reduction 

technology has been optimized to minimize impingement mortality. If the Director 

concludes that the study does not establish that the proposed technology is the best 

technology available for impingement reduction for the site, she must determine other 

impingement reduction controls for the facility. The Director will notify the U.S. Fish and 

Wildlife Service and National Marine Fisheries Service in instances where threatened or 

endangered of non-fragile species are identified in the study during the public notice 

period in accordance with § 124.10.. The Director may request further monitoringdata 

collection and information as part of the impingement technology performance 

optimization study, including extending the study period beyond two years. The Director 

may also consider previously collected biological monitoring data and performance 

reviews as part of the study. The Director must include in the permit those operational 

measures and BMPs identified in the study and deemed as necessary by the Director to 

verifiable and enforceable permit conditions that ensure optimized operation of the 

modified traveling screens or other systems of technologies. will perform as 

demonstrated. The Director may waive all or part of the Impingementimpingement

technology performance optimization study at 40 CFR 122CFR122.21(r)(6) after the first 

permit cycle wherein the permiteepermittee is deemed in compliance with 124125.94(c). 
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 (f) Site-specific entrainment requirements. The Director must establish sitespecific requirements for entrainment after reviewing the information submitted under 40 

CFR 122.21(r) and § 125.95. These entrainment requirements must reflect the Director’s 

determination of the maximum reduction in entrainment warranted after consideration of 

factors relevant for determining the best technology available for minimizing adverse 

environmental impact at each facility. These entrainment requirements may also reflect 

any control measures to reduce entrainment of Federally-listed threatened and 

endangered species and designated critical habitat (e.g. prey base). The Director may 

reject an otherwise available technology as a basis for entrainment requirements if the 

Director determines there are unacceptable adverse impacts that cannot be 

mitigated.including impingement, entrainment, or other adverse effects to Federallylisted threatened or endangered species or designated critical habitat. Prior to any permit 

reissuance after December 31, 2016,[INSERT date 45 months after effective date of 

final rule], the Director must review the performance of the facility’s installed 

entrainment technology to determine whether it continues to meet the requirements of § 

125.94(d). 

 (1) The Director must provide a written explanation of the proposed 

entrainment determination in the fact sheet or statement of basis for the proposed permit 

under 40 CFR 124.7 or 124.8. The written explanation must describe why the Director 

has rejected any [entrainment] control technologies or measures that perform better than 

the selected technologies or measures, and must reflect consideration of all reasonable 
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attempts to mitigate any adverse impacts of otherwise available better performing 

entrainment technologies. 

 (2) The proposed determination in the fact sheet or statement of basis must be 

based on consideration of any additional information required by the Director at § 

125.98(i) and the following factors listed below. The weight given to each factor is 

within the extentDirector’s discretion based upon the applicant submitted information 

under 40 CFR 122.21(r), and in subsequent permit cycles, § 125.96 and § 

125.97:circumstances of each facility. 

 (i) Numbers and types of organisms entrained;, including, specifically, the 

numbers and species (or lowest taxonomic classification possible) of Federally-listed, 

threatened and endangered species, and designated critical habitat (e.g., prey base);

 (ii) Impact of changes in particulate emissions or other pollutants associated 

with entrainment technologies; 

 (iii) Land availability inasmuch as it relates to the feasibility of entrainment 

technology; and

 (iv) Remaining useful plant life; and 

 (v) Quantified and qualitative social benefits and costs of available entrainment 

technologies when such information on both benefits and costs is of sufficient rigor to 

make a decision. 

 (3) The proposed determination in the fact sheet or statement of basis may be 

based on consideration of the following factors to the extent the applicant submitted 

information under 40 CFR 122.21(r) on these factors: 
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 (i) Entrainment impacts on the waterbody; 

 (ii) Thermal discharge impacts; 

 (iii) Credit for unit retirementsreductions in flow associated with the retirement 

of units occurring within the ten years preceding [INSERT effective date of the final 

rule]; 

 (iv) Impacts on the reliability of energy delivery within the immediate area; 

 (v) Impacts on water consumption; and 

 (vvi) Availability of process water, gray water, waste water, reclaimed water, or 

other waters of appropriate quantity and quality for reuse as cooling water. 

 (4) In addition, the proposed determination in the fact sheet or statement of 

basis may be based on consideration of other relevant factors, including the quantified 

and qualitative social benefits and costs of available entrainment technologies, including 

ecological benefits and benefits to threatened and endangered species so long as the 

applicant has submitted the information specified in § 122.21(r)(10), (11) and (13). (4)

If all technologies considered have social costs not justified by the social benefits, or 

have unacceptable adverse impacts that cannot be mitigated, the Director may determine 

that no additional control requirements are necessary beyond what the facility is already 

doing. The Director may reject an otherwise available technology as a BTA 

standardsstandard for entrainment if the social costs are not justified by the social 

benefits. The Director may not reject an otherwise available technology as a basis for 

entrainment requirements based on a comparison of social costs and social benefits if the 

information on benefits is inadequate or has been waived by the Director. 
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 (5) If the applicant is subject to 40 CFR 122.21(r)(1)(ii)(B) but does not submit 

all the application information required by 40 CFR 122.21(r)(1)(ii)(B) , the Director 

must base the site-specific BTA impingement mortality and entrainment requirement on 

the performance achieved by a closed-cycle recirculating system. 

 (6) In instances where the Director determines that no additional control 

requirements are necessary for a given facility and the facility has been identified as 

likely having more than minor detrimental effects or contributing unacceptable stress to 

threatened or endangered species, the Director may coordinate with the U.S. Fish and 

Wildlife Service and National Marine Fisheries Service to in the selection of additional 

technologies or operational measures for the facility. These additional requirements in no 

way authorize take, as defined at 16 U.S.C. 1532(19), as such take is prohibited unless it 

is exempted pursuant to 16 U.S.C. 1536(o) or permitted pursuant to 16 U.S.C. 1539(a). 

 (g) Ongoing permitting proceedings. In the case of permit proceedings begun 

prior to [INSERT effective date of the final rule] whenever the Director has determined 

that the information already submitted by the owner or operator of the facility is 

sufficient, the Director may proceed with a determination of BTA standards for 

impingement mortality and entrainment without requiring the owner or operator of the 

facility to submit the information required in 40 CFR 122.21(r). The Director’s BTA 

determination may be based on some or all of the factors in (f)(2) and (3) and the BTA 

standards for impingement mortality at § 125.95(c). In making the decision on whether to 

require additional information from the applicant, and what BTA requirements to include 

in the applicant’s permit for impingement mortality and site-specific entrainment, the 
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Director should consider whether any of the information at 40 CFR 122.21(r) is 

necessary. 

 (h) The Director must transmit all permit applications for facilities subject to 

Subpart J to the appropriate Field Office of the U.S. Fish and Wildlife Service and/or 

Regional Office of the National Marine Fisheries Service upon receipt for a 60 day 

review prior to public notice of the draft or proposed permit. The Director shall provide 

the public notice and publican opportunity to comment period as required under 40 CFR 

124.10. and must submit a copy of the fact sheet or statement of basis (for EPA-issued 

permits), the permit application (if any) and the draft permit (if any) to the appropriate 

Field Office of the. Fish and Wildlife Service and/or Regional Office of the National 

Marine Fisheries Service. This includes notice of specific cooling water intake structure 

requirements at 124.10(d)(1)(ix) and notice of the draft permit. ),notice of the draft 

permit, and any specific information the Director has about threatened or endangered 

species and critical habitat that are or may be present in the action area, including any 

proposed control measures and monitoring and reporting requirements for such species 

and habitat.

 (i) Additional information. In implementing the Director’s responsibilities under 

the provisions of this subpart, the Director is authorized to inspect the facility and to 

request additional information needed by the Director for determining permit conditions 

and requirements., including any additional information from the facility recommended 

by the Services upon review of the permit application under paragraph (h). 
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 (j) In no event may any determination by the Director concerning applicable 

BTA standards authorizeNothing in this subpart authorizes the take, as defined at 16 

U.S.C. 1532(19), of threatened or endangered species of fish or wildlife. Such take is 

prohibited under the Endangered Species Act unless it is exempted pursuant to 16 U.S.C. 

1536(o) or permitted pursuant to 16 U.S.C. 1539(a). or harm to a listed critical habitat 

Absent such exemption or permit, any facility operating under the authority of this 

regulation must not take threatened or endangered wildlife. 

 (k) The Director must submit at least annually to the appropriate EPA Regional 

Office facilities’ annual reports submitted pursuant to § 125.97(g), for compilation and 

transmittal to the Services. 

§ 125.99 [Reserved]