*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 1 of 567

EO12866_Cooling Water Intakes_2040_AE95_Final_Preamble+Rule _20140519

ENVIRONMENTAL PROTECTION AGENCY

40 CFR Parts 122 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: 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 (mgd) of water from waters of the United States and use at least 

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 and provide
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 2 of 567

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 also responds to judicial remand of aspects of 

the previously promulgated Phase II and Phase III section 316(b) rules. In addition, EPA 

is also responding to an earlier judicial decision by removing from the previously

promulgated Phase I new facility rule a 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

web 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 

the internet and will be publicly available only in hardcopy form. Publicly available 

docket materials are available either electronically through www.regulations.gov or in 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 3 of 567

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 biological information, 

contact Tom Born at 202-566-1001; e-mail: born.tom@epa.gov. For additional economic 

information, contact Wendy Hoffman at 202–564–8794; e-mail: 

hoffman.wendy@epa.gov. For additional technical information, contact Paul Shriner at 

202–566–1076; e-mail: shriner.paul@epa.gov.

SUPPLEMENTARY INFORMATION:

What Facilities 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 

design intake flow (DIF) greater than 2 mgd. 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 subject to permit conditions implementing 

CWA section 316(b), developed by the NPDES Permit Director on a case-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
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 4 of 567

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 United 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 industry sectors of facilities subject to this final rule. This table is 

not intended to be exhaustive; facilities in other industries not listed in Exhibit 1 could 

also be regulated. The 4-digit NAICS industry sectors may include 6-digit NAICS 

industry sub-sectors with operations that are not dependent on cooling water.

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

Category

4-Digit NAICS

Industry 

Sectors

NAICS Definition

Federal, State and Local Government

Electric Power 

Industry

2211

Electric Power Generation, Transmission and 

Distribution

Industry

Electric Power 

Industry

2211

Electric Power 

Generation, 

Transmission and 

Distribution

Industry

Primary 

Manufacturing 

Industries

3112

Grain and Oilseed 

Milling
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 5 of 567

3113

Sugar and 

Confectionery 

Product 

Manufacturing

3121 Beverage Manufacturing

3221

Pulp, Paper, and 

Paperboard Mills

3222

Converted Paper 

Product 

Manufacturing

3241

Petroleum and Coal 

Products 

Manufacturing

3251 Basic Chemical Manufacturing

3252

Resin, Synthetic 

Rubber, and 

Artificial Synthetic 

Fibers and 

Filaments 

Manufacturing

3253

Pesticide, Fertilizer, 

and Other 

Agricultural 

Chemical 

Manufacturing

3254

Pharmaceutical and 

Medicine 

Manufacturing

3256

Soap, Cleaning 

Compound, and 

Toilet Preparation 

Manufacturing

3259

Other Chemical 

Product and 

Preparation 

Manufacturing

3311

Iron and Steel Mills 

and Ferroalloy 

Manufacturing
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 6 of 567

3312

Steel Product Manufacturing from Purchased 

Steel

3313

Alumina and 

Aluminum 

Production and 

Processing

Industry

Other 

Industries

1119 Other Crop Farming

2122 Metal Ore Mining

3133

Textile and Fabric 

Finishing and Fabric 

Coating Mills

3211

Sawmills and Wood 

Preservation

3314

Nonferrous Metal 

(except Aluminum) 

Production and 

Processing

3322

Cutlery and 

Handtool 

Manufacturing

3329 Other Fabricated Metal Product Manufacturing

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 persons listed for 

technical information in FOR FURTHER INFORMATION CONTACT.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 7 of 567

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.

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:
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 8 of 567

 Economic Analysis for the Final Section 316(b) Existing Facilities Rule (EPA821-R-14-001), referred to as the EA throughout. This document presents the 

analysis of compliance costs, economic 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-14-005), referred to as the BA throughout. This document examines cooling 

water intake structure impacts and regulatory benefits at the regional and national

levels.

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

Rule (EPA-821-R-14-002), referred to as the TDD 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.

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?
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 9 of 567

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

Final Rule?

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 Data Updates and Revisions to the Proposed Rule

A. Data Updates

B. Regulatory Approach and Compliance

C. New Units

VI. Basis for the Final Regulation

A. EPA’s Approach to BTA

B. Overview of Final Rule Requirements

C. Technologies Considered to Minimize Impingement and Entrainment

D. Technology Basis for Today’s Final Rule

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

I. Site-Specific Consideration of Entrainment Controls
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 10 of 567

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

Availability (NODAs)

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. Endangered 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 Will I Be Required to Keep?

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

K. Protection of Endangered and Threatened Species and Designated Critical Habitat

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 Impacts

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
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 11 of 567

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

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 (mgd) of water from waters 

of the United States and use at least 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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 12 of 567

(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 the restorationbased 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, 

 

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.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 13 of 567

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 

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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 14 of 567

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

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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 15 of 567

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 

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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 16 of 567

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. Closed-cycle cooling is a technology that recirculates cooling 

water, reducing withdrawals from surface waters. Closed-cycle cooling can reduce water 

withdrawals by at 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). Operators

who retrofit closed-cycle cooling systems have a financial incentive not to run their 

system in closed-cycle mode during summer months. Thus, decision making at facilities 

that use cooling water may not take society’s preferences for fish protection into account 

in their actions.

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. Directors may have required controls to 

meet state water quality standards, particularly with regard to temperature. Based 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

on aquatic organisms. 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 17 of 567

3. Costs and Benefits

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

complying with the final rule, accounting for both the existing CWIS unit provision and 

the new unit 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 site-specific 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 today’s final rule – including standards for both existing units

and new units at existing facilities – will achieve monetized benefits to society of $33

million and $29 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 by the 

Agency and described in the June 12, 2012 Notice of Data Availability (77 FR 34927
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 18 of 567

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

will reduce greenhouse gas (GHG) emissions by 9.3 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 $12 million to $13 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

provisions, EPA estimates that a substantial majority (86 percent) of electric generators

will incur compliance costs of less than 1 percent of revenue, indicating the minor impact 

of the rule on these facilities.

 

2 DCN refers to a document control number. An index of DCNs can be found in the docket for this action.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 19 of 567

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

regulated facilities. EPA estimates that 504 out of 509 facilities will incur costs less than 

one percent of revenue, five will incur costs between one and three percent, and none will 

incur costs greater than 3 percent. In addition, EPA estimates that no manufacturing

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 unit

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 unit

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 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 estimates, on average, 

across the United States, that the final rule will increase electricity production costs by

0.009 cents per kWh, causing an estimated 0.1 percent increase in average electricity 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 20 of 567

prices. The corresponding annual increase in electricity costs is approximately $1.03 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. In the course of their operations, electric power facilities 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 BTA for minimizing the adverse environmental 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. Jackson, No. 93 Civ. 

0314 (AGS). (For a more detailed discussion of the settlement agreement, see Section 

II.C.)
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 21 of 567

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

(design intake flow) of more than 2 mgd. 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-2 and I-3.

Exhibit I-2. 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-3. 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 and entrainment standards for 

new units at § 125.94(e)

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

Case-by-case BPJ permitting per § 125.90(b)
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 22 of 567

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 entrainment3does 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 

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 

 

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.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 23 of 567

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 facilities4that meet all 

following criteria:

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

 At least 25 percent of the water actually withdrawn – actual intake flow (AIF) – is 

used exclusively for cooling purposes.

 

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 owner or operator of the facility is required to do the activity.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 24 of 567

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 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. 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.

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

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

withdrawn exclusively for cooling purposes (on an actual intake flow basis) are subject to 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 25 of 567

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 powergenerating 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 70 percent of 

manufacturers and 87 percent of power-generating facilities that meet the first three 

criteria for applicability outlined above also use 25 percent or more of intake 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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 26 of 567

purposes – the Director must set appropriate requirements on a case-by-case basis, using 

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 caseby-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).

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 

 

5

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

cooling water intake structure.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 27 of 567

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 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 slightly revised the definition of cooling water intake structure from 

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

as the total physical structure and any associated constructed waterways used to 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 United 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 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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 28 of 567

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 

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 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, 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 29 of 567

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 

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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 30 of 567

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, 

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 a 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. As 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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 31 of 567

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 make-up 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 

subject to today’s rule. 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 created6for 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. Some of these impoundments may qualify for the waste treatment 

 

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. 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 32 of 567

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 addressed 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.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 33 of 567

EPA acknowledges that the point of compliance for facilities located on 

impoundments may also vary depending on where the facility withdraws from a water of 

the United States. Again, only cooling water systems with withdrawals 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 determine where 

within a facility’s cooling water intake structure 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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 34 of 567

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 

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 withdraw volumes of water for cooling that

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 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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 35 of 567

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 method 

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 years.7 Both of these methods are used in 

today’s rule.

Today’s final rule applies to facilities that have a total DIF of greater than 2 mgd

(see § 125.91).8 At a threshold of 2 mgd, today’s rule covers 99.8 percent of the total 

water withdrawals by utilities and other industrial sources (if the other criteria for 

coverage are met), which includes 70 percent of manufacturing facilities and 87 percent 

of electric generators. EPA also chose the greater than 2 mgd threshold because it was

consistent with the applicability criteria in the Phase I rule.10

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 

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 

 

7

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

average flows over the previous 5 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.

10 For more information, see 65 FR 49067, August 10, 2000.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 36 of 567

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 

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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 37 of 567

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 

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
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 38 of 567

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, 

co-location would be better determined by multiple CWIS facilities on the same 

waterbody, rather than distance. 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 39 of 567

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 Data, 

and Cooling Water Intake System Data. In addition, these facilities must submit 

additional facility-specific information including the selected impingement compliance 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 40 of 567

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 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) 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 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 

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 information that 

will allow the Director to verify its determination of whether it meets the 125 mgd AIF 

threshold.

 

11 The final rule allows 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.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 41 of 567

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

the entrainment study because this threshold will capture 90 percent of the actual flows 

but will apply to only 30 percent of existing facilities. Further, 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 two-thirds 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 as 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 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 

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 facility can physically withdraw water 

from a source waterbody (usually normalized to a daily rate in mgd). This also means that 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 42 of 567

a facility 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 

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 

 

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.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 43 of 567

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 

existing LNG facilities. LNG facilities that withdraw any volume of water for cooling 

purposes will be subject to site-specific, BPJ 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 Directors, on a case-by-case basis using BPJ, determine 

BTA for existing offshore oil and gas extraction facilities, existing offshore seafood 

processing facilities, and existing LNG terminals.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 44 of 567

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 those 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. Under today’s rule, 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 units newly constructed at an existing facility for the same 

general industrial operation, such units do constitute a new unit at existing facilities and, 

as such, are subject to today’s final rule.

On the basis of the public comments received on how to define “new unit,” EPA 

provides a clear definition for this term in the final rule. The definition for a new unit at 

an existing facility establishes a clear regulatory framework for both affected facilities 

and Directors. This definition captures facilities that are undergoing major construction 

projects involving the construction of a new stand-alone unit, while not discouraging 

upgrades. 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. 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 45 of 567

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

at existing facilities described below.

1. Electric Generators

The final rule defines a new unit at an existing facility as a newly built, standalone unit that is constructed at an existing facility and that does not meet the definition 

of a new facility. An existing unit that is repowered or undergoes significant 

modifications (such as where the turbine and condenser are replaced) is not considered a 

new unit. Exhibit I-4 below provides several examples and whether these hypothetical 

units will be defined as new or existing units.

Exhibit I-4. Examples of new and existing units at existing electric generation 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 intake structure

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 

2. Manufacturers

At manufacturing facilities that generate electricity onsite, the previous discussion 

of how to define new units at existing electric generating 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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 46 of 567

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

facilities. However, manufacturers may have opportunities to reuse cooling water that 

power plants do 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, 

It is not as easy to identify a similar conceptual approach for defining new 

manufacturing units at 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 generating units where the majority of cooling water comes from a single process 

source (the steam condenser), manufacturing units may include many separate noncontact or contact cooling water sources dispersed throughout the production processes 

 

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

recirculating system requirements but contact cooling water does nonetheless fall within the definition of 

cooling water at § 125.92.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 47 of 567

and the facility. Thus, a definition for manufacturing units must take into consideration a 

broader category of cooling water sources.

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. 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.

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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 48 of 567

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-5 below provides several examples of 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 new construction comprises a stand-alone unit. For the purposes of today’s 

final rule, the Director does not need to address whether the stand-alone unit is for the 

same 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 whether the 

construction results in a stand-alone unit.

Exhibit I-5. 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

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)

An existing unit is retired before or after a new unit is Replacement or upgrade of ancillary equipment (e.g., 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 49 of 567

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)

pumps, motors, HVAC, etc.)

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)

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 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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 50 of 567

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 

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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 51 of 567

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.

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 waterbody 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 waterbody 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 § 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 52 of 567

125.87(a), and at § 125.87(a)(2) incorrectly refer to § 122.21(r)(3) and are thus being 

corrected.

II. Legal Authority for and Background of the Final Regulation

A. Legal Authority

Today’s final rule is issued under the authority of Clean 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 its earlier rule establishing section 316(b) 

requirements for new facilities. Specifically, EPA is removing a provision that would 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 53 of 567

have allowed a restoration-based alternative for complying with performance standards as 

well as the associated monitoring and other requirements for demonstrating compliance.

C. Background

1. The Clean Water Act

a. General

The Federal Water Pollution Control Act, also known as the CWA, 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-six 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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 54 of 567

permits control the discharge of pollutants by requiring dischargers to meet technologybased and possibly water-quality-based effluent limitations. Under section 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 

 

17 For example, California policy addressing 19 coastal power plants would not affect the compliance costs 

of inland facilities.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 55 of 567

basis for discharge requirements in wastewater discharge permits. EPA develops these 

effluent limitations guidelines and standards for categories of industrial dischargers on 

the basis of the pollutants of concern discharged by the industry, 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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 56 of 567

water, in contrast to other provisions of the Act that regulate the discharge of pollutants 

into waters of the United States.

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 sections 304 and 306, section 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 sections 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 

 

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.”
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 57 of 567

sections in discerning what factors Congress intended EPA to consider in determining 

BTA.

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 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

 

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.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 58 of 567

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 

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.”).
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 59 of 567

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, 

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 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 nonwater quality environmental impact and energy requirements.” 33 U.S.C. 1316(b)(2)(B).

Similarly, CWA section 301 requires EPA, 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, while it shares some of the same words used in sections 301(b) and 306, its 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 60 of 567

language is different.20 These differences in the statutory descriptions, coupled with the 

brevity of section 316(b) itself, prompt EPA to examine the factors described in section 

301, 306 and, ultimately, section 304 where relevant in EPA’s determination of the “best 

technology available to minimize adverse environmental impact” of cooling water for

intake structures for existing facilities.

As 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 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 

 

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).
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 61 of 567

implementing sections 301, 304, as 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 sitespecific basis, where EPA has considered the costs of technologies in relation to the 

benefits of minimizing adverse environmental impact in establishing 316(b) 

requirements. 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. 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. 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. 

 

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, 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 62 of 567

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 

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 

 

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.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 63 of 567

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 

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
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 64 of 567

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 

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, 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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 65 of 567

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.

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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 66 of 567

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 consideration 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 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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 67 of 567

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, 

facilities that withdraw equal to or greater than 10 mgd 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 

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 had 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
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 68 of 567

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 waterbody 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 Section I above.

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
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 69 of 567

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

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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 70 of 567

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.

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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 71 of 567

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 

controls on the shoreline near the source waterbody (i.e., calculation baseline, for more 

details see Section 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 waterbody), rate of use 

(capacity utilization rate), and the proportion of the waterbody withdrawn.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 72 of 567

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 

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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 73 of 567

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 practicable 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 

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
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 74 of 567

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 did not select closed-cycle 

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 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.

 

23Rhode Island, Connecticut, Delaware, Massachusetts, New Jersey, and New York.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 75 of 567

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)).

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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 76 of 567

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, 

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
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 77 of 567

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 

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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 78 of 567

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 

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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 79 of 567

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 

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 industrial buildings, roadways, canals, 

impoundments, and other water storage or conveyance structures have been constructed 

 

24 Rapport, D. J., & Whitford, W. G. (1999). How Ecosystems Respond to Stress. BioScience, 49(3), 193-

203. See DCN 10-4871.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 80 of 567

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 

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 section 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., 

 

25 Abt Associates, Inc. (2010). Source Water Body Comparisons (Under Work Assignment 2-09, Task 4) 

(pp. 13). Cambridge, MA. See DCN 10-4504.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 81 of 567

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.

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.

 

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. Annual Review of 

Ecology & Systematics, 31, 481-531. See DCN 10-4880.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 82 of 567

C. Effects of CWIS on Aquatic Ecosystems

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 threatened 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 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,

approximately 5.4 percent of the estimated A1E population of the Southern New 

England/Massachusetts stock of winter flounder (Pseudopleuronectes americanus) is lost 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 83 of 567

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

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 

 

27 Northeast Fisheries Science Center (NEFSC) of the NOAA National Marine Fisheries Service. (2011). 

52nd Northeast Regional Stock Assessment Workshop (52nd SAW): Assessment Summary 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.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 84 of 567

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

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 

 

30 Abt Associates, Inc. (2010). Source Water Body Comparisons (Under Work Assignment 2-09, Task 4) 

(pp. 13). Cambridge, MA. See DCN 10-4504.

31 Abt Associates, Inc. (2009). Summary of Ecological Effects of Thermal Discharge (pp. 28). Cambridge, 

MA. See DCN 10-4505.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 85 of 567

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 industrial 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 

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 

 

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.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 86 of 567

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 regulated

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 

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 

 

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.

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.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 87 of 567

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 facilities can lead to localized areas of depressed fish 

and shellfish abundance. Industrial facilities (and the intake volume they represent) are 

located in a non-uniform manner along coastlines and rivers. 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.

 

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.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 88 of 567

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, 

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 

 

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.

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.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 89 of 567

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 these 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 show more than 20 percent of all 

facilities on inland waters 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 regulated facilities (approximated by CWIS 

 

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.

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.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 90 of 567

latitude and longitude) shows 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.

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

Facilities

The final rule requires that existing facilities 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; 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 91 of 567

(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 

[INSERT 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;

(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.

 

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.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 92 of 567

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 data collection demonstrating that the operation 

of the system of technologies, operational measures and best management 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 a 12-month impingement mortality performance of all life stages of fish and 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 93 of 567

shellfish of no more than 24 percent mortality, including latent mortality, for all nonfragile 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 12-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.

The owner or operator of an existing facility must meet the impingement 

mortality requirements as soon as practicable after issuance of a final permit establishing 

the entrainment requirements under § 125.94(d).

Today’s final rule also allows the Director, based on review of site-specific data, 

to conclude that a de minimis 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 Director 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 operating with a capacity utilization of less than 8 percent 

 

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.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 94 of 567

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 such

units, the rule does not prescribe a single nationally applicable entrainment performance 

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) 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, 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 95 of 567

new unit standards).

43 Under the new unit standards, 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 

unit standard. Under the alternative new unit 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 that 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 through flow reductions 

commensurate with the use of a closed-cycle 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.

The new unit entrainment standards do not apply to certain water withdrawals

including (1) cooling water used by manufacturing facilities for contact cooling purposes; 

(2) portions of those water withdrawals for auxiliary cooling uses totaling less than 2 

 

43 EPA expects that all new units will comply with these requirements through the installation of a closedcycle cooling system, which is one of the most effective technologies for reducing impingement and 

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.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 96 of 567

mgd; (3) any volume of cooling water withdrawals used exclusively for make-up water at 

existing closed-cycle recirculating systems;44 and (4) 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 the new unit 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 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).

 

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
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 97 of 567

D. 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, 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 

would result in a conflict with a safety requirement established by these 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.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 98 of 567

V. Summary of Data 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 (Notice of Data Availability) (77 FR 34315, June 11, 2012 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 

stating the amount of data to develop the proposed impingement mortality performance 

standard was too limited. EPA received more than 80 additional documents containing 

impingement and entrainment data. EPA reviewed these materials and 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, 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 99 of 567

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 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 for 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 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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 100 of 567

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 data would 

reflect only the effects of its improvements to the CWIS technology, and not be 

confounded by effects of data collection that are not caused by impingement. 

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. At proposal, EPA counted all fish that died at any 

time during the holding period. 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
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 101 of 567

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 12-6703.)

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 12-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 24 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 Section VI and Chapter 11 of the 

TDD.

EPA also reevaluated its approach to compliance monitoring for the impingement 

mortality performance standard. 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 irrespective of the 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 102 of 567

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 such, today’s final rule includes seven 

compliance alternatives, only one of which requires biological compliance monitoring.

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 gather

biological data at a minimum frequency of monthly for a period of two years in order to 

calculate their 12-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 frequency of at least monthly in order to calculate its

12-month average impingement mortality. The 12-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 compliance monitoring. Further, prior to a subsequent permit application, a 

facility could collect sufficient performance data to demonstrate to the satisfaction of the 

Director that its “systems of technologies” compliance alternative is BTA at that facility. 

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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 103 of 567

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 

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 recirculating 

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

compliance alternatives. To ensure that this technology will be consistent at all 

 

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. 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 104 of 567

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.

 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.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 105 of 567

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 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 seven compliance alternatives for

the impingement standard. One of these alternative 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 non-fragile 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 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 comply with the impingement mortality standard by employing one of the preapproved 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 annual monitoring and reporting costs

from approximately $47 million under the proposed rule to approximately $27 million

under the final rule. 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 106 of 567

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. Based on consideration of 

public comment, EPA decided not to employ the survey results for purposes of decisionmaking 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 requirements. 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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 107 of 567

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 compliance 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 appropriate. However, recognizing that for some 

sites technologies other than modified traveling screens may allow a facility to achieve 

the same level of performance, EPA has included compliance options that provide for 

more flexibility and allow consideration of the performance of combinations of 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 108 of 567

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 pre-approved 

and streamlined technologies include a closed-cycle recirculating system, existing 

offshore velocity cap, and maximum design intake velocity of 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 the 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 concluded that it is not appropriate to add conditions 

to the definition of closed-cycle cooling because water may be withdrawn 

for purposes of replenishing losses to a closed-cycle recirculating system 

other than those due to blowdown, drift, and evaporation from the cooling 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 109 of 567

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 thus meets 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 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 a

0.5 fps intake velocity achieves the IM standards. EPA’s record shows an 

intake 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 performance standard that is the goal for all 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 110 of 567

facilities. There are two ways to demonstrate compliance using intake 

velocity. First, an intake with a maximum design 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.

 Systems of Technologies to Meet the 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 

 

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. 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 111 of 567

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. 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 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.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 112 of 567

 Numeric IM Performance 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 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 

standard 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 

cooling systems comply with the IM standards. The proposed rule’s definition of “closedcycle 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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 113 of 567

chlorides in recirculated water relative to make-up water, and thus how well a system 

recycles intake water before replacing it with new withdrawals. This is not to be confused 

with cycles of flow, as some commenters appeared to do. 

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 

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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 114 of 567

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 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 system can generally be deemed 

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. 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 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 and 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 further recognizes that in certain unavoidable circumstances, these levels 

for COC or percent flow reduction might not be achievable at all facilities. Such 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 115 of 567

circumstances could include situations where water quality-based discharge limits might 

limit the concentration of a pollutant that is not readily treatable in the cooling tower 

blowdown or situations where varying source water quality could lead to unavoidable 

problems concerning scale formation, solids buildup, corrosion, or media fouling. Such 

facilities should demonstrate these circumstances to their Director and indicate the 

measures they have taken to minimize makeup flows. The Director will retain the 

discretion to conclude that the particular facility employs a closed-cycle recirculating 

system when the benchmarks are not met. 

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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 116 of 567

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 

requirements could be difficult to comply with, particularly where cooling systems 

employ impoundments or basins downstream of the initial intake structure. 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 and EPA made a number of adjustments to the rule to protect threatened and 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 117 of 567

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 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

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 

eight 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. In some cases, impingement compliance can be 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 118 of 567

attained with entrainment technologies. For example, the Director may determine that the 

installation of modified fine-mesh traveling screens and narrow-slot wedgewire screens 

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 practicable 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 mean a stand-alone unit at an 

existing facility the construction of which is commenced after the effective date of 

today’s final rule; consists of only a stand-alone unit constructed at an existing facility; 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 119 of 567

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, EPA has reevaluated the requirements for existing facilities under 

CWA section 316(b). As discussed above, EPA collected additional data and information 

to update its assessment of the efficacy of various technological measures for reducing 

IM&E and analyses prepared for the earlier rule-making efforts. EPA’s additional 

technical rigor provided a strengthened analysis of different technologies for reducing IM 

and their effectiveness. As a result of its revised assessments and further consideration of 

the factors affecting the availability of different technology in a wide range of settings, 

EPA has decided not to re-promulgate requirements for existing facilities that mirror 

those of the final Phase II rule. Further, 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 subject to section 316(b) in this rule (i.e., both those subject to the

Phase II rule and some of those subject to the Phase III rule). For a brief description of 

the final rule, see Section IV.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 120 of 567

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 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 with broad discretion in determining what is the “best” technology that is 

“available” for minimizing adverse environmental impact. As the Supreme Court has

further explained, under section 316(b), the “best” technology “available” may reflect a 

consideration of a number of factors and “best” does not necessarily mean the technology

that achieves the greatest reduction in environmental harm that the regulated universe can 

 

47 The factors specifically delineated in CWA sections 301 and 306 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).
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 121 of 567

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 must tailor regulations to 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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 122 of 567

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 final rule justify

its costs. For additional discussion, see Section VI below.

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 Section 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 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.

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, and then evaluated

costs associated with these technologies (including potential costs to facilities and 

households), and their economic impacts. EPA also reviewed the effectiveness of these 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 123 of 567

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 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, in the case of the BTA standard for 

impingement mortality, EPA based the standard on performance of well-operated

modified traveling screens with a fish handling and return system as defined more 

specifically by the rule. Under the BTA IM standard, a facility has a 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.

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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 124 of 567

modified traveling screens, and therefore will generally comply with the BTA 

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 

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 modified 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 

 

48 Or any of the IM compliance alternatives.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 125 of 567

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 the 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 comply with the BTA standard 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. As 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, 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(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 the 

regulatory definition on the commonly found features of modified traveling screens used 

in developing the BTA impingement mortality standard. 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 126 of 567

In addition, the final rule also provides a compliance option that would allow 

facilities the option of demonstrating to the Director on a site-specific basis, similar to the 

showing for modified traveling screens, that a system or combination of technical and 

operational measures will achieve the BTA standard for impingement mortality at a 

particular site. Using 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 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 site-specific basis 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 data 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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 127 of 567

application and rule requirements for biological data collection, including the Source 

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. 

Lastly, a facility may 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 existing 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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 128 of 567

submitted in the permit application, prescribes procedures that the Director must follow 

in decision making and factors that must be considered in determining what entrainment 

controls and associated requirements are BTA on a site-specific basis.

As previously noted, EPA looked at a number of factors in considering what 

national entrainment standard it should adopt. 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 this technology as the basis for a national BTA standard for

entrainment: land availability, air emissions, 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 section describes in detail the 

above considerations.

C. 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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 129 of 567

and municipal uses. 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 harnessed to 

a productive end and therefore view as waste heat.

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 Section III above.

For purposes of this rule, EPA is adopting the following conventions for defining

impingement and entrainment and mortality:

 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 

 

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.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 130 of 567

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 

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

 

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.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 131 of 567

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 or 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. 

Also see Chapter A7 of the Phase II Regional Studies Document (DCN 6-0003; EPAHQ-OW-2002-0049-1490).
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 132 of 567

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 

result in very high entrainment reductions by converting entrainment to impingement, but 

these impinged organisms may have an even lower likelihood of surviving impingement 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 133 of 567

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 

technologies are installed to collect and return organisms to the source water, allowing 

impingement to occur but possibly preventing impingement mortality.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 134 of 567

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 waterbody, 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 

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.

Sections 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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 135 of 567

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 

dissipating more heat), when fewer generating units are operating or when fuel is more 

 

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.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 136 of 567

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, many baseload generating units and continuously operated 

manufacturing processes will obtain limited 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 have 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 

to reduce entrainment, because entrainment often has a peak season, particularly during a 

 

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.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 137 of 567

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 periods, 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 recirculating 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 

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 

 

53 See DCN 10-6702 and its attachments for examples of spawning “seasons.”
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 138 of 567

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. The 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 

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 

 

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.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 139 of 567

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 

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

 

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.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 140 of 567

uses a once-through or closed-cycle recirculating 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.

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

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, 

 

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.).
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 141 of 567

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 

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 waterbody. Because the heat is transferred through evaporation, the 

amount of water withdrawn from the water source is greatly reduced, though not 

 

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.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 142 of 567

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 waterbody) for heat dissipation. 

When once-through cooling is used and withdrawals are a significant portion of the 

source waterbody, the return of heated water might contribute to greater evaporation from 

the waterbody relative to the waterbody’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 12-6673, including a comparison to 

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, 

 

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.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 143 of 567

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 

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 

facilities (these costs are now explicitly considered in the benefit-cost analysis; see 

 

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.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 144 of 567

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 

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 

 

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.

61 The construction and capital costs for dry cooling towers have been reported as four 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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 145 of 567

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 

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

 

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.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 146 of 567

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 impoundment

and then discharges the heated effluent back to the impoundment, 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). 

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 

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 traveling screens and cylindrical wedgewire screens. Not described in this 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 147 of 567

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

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
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 148 of 567

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 waterbody. (See Chapter 6 of the 

TDD for an illustration of these screens.)

When necessary conditions regarding placement in the waterbody 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 waterbody. The screen orientation allows 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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 149 of 567

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 waterbody’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 

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 

 

62 Note that this is entrainment exclusion and not necessarily related to the survival of entrainable 

organisms.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 150 of 567

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 

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 

 

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 as 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.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 151 of 567

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 

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.

 

65 A facility could also increase its intake velocity.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 152 of 567

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

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 

 

66 Barrier net mesh sizes vary, depending on the configuration, level of debris loading, species to be 

protected, and other factors.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 153 of 567

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 

them to the waterbody 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 

 

67 This facility ceased operations for reasons unrelated to any requirements or measures addressing cooling 

water intake impingement or entrainment.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 154 of 567

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 

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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 155 of 567

area in the source waterbody. 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, 

sometimes referred to as post-Fletcher modifications, show low levels of impingement 

mortality across a wide variety of 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.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 156 of 567

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 

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 

 

68 Others can be fitted with a cylindrical wedgewire screen, or might simply be an open pipe.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 157 of 567

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.

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 

 

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.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 158 of 567

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 

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 

 

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 DCN 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.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 159 of 567

withdrawals (water volumes) are large. 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. 

D. Technology Basis for Today’s Final Rule

As described above, EPA examined the full range of technologies that reduce 

impingement or entrainment or both. From an assessment of all factors, EPA identified 

one technology that is best technology available for minimizing the adverse impacts of 

impingement mortality at existing facilities: modified traveling screens with a fishfriendly fish return. EPA identified no single best technology that is available for 

minimizing entrainment at existing facilities for today’s final rule. For new units at 

existing facilities, EPA identified mechanical draft wet cooling systems as BTA for both

impingement and entrainment.

71

 

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.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 160 of 567

EPA did not identify any single technology or group of technology controls as the 

basis for establishing the national BTA standard for entrainment for existing units.

Instead, EPA has established a national BTA standard for entrainment for existing units

that requires determination of BTA entrainment requirements on a site-specific basis in a 

structured permitting setting. The framework for 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 BTA controls.

1. Alternative Impingement Mortality Standards for Existing Units

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 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 

 

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 impingement 

mortality performance 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.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 161 of 567

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 option for complying with the BTA impingement mortality

standard in today’s final rule, a facility may rely on any technology it chooses so long as 

it demonstrates through biological compliance monitoring that it achieves the required 12 

month impingement mortality performance standard73 that EPA calculated 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 12 

month percent mortality performance at § 125.94(c)(7) on data from facilities with 

traveling screens modified with features to improve the post-impingement 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 12 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. EPA established the 12 month percent mortality as 24

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 

 

73 In the record, EPA may also refer to this as the 12-month percent survival performance standard, % SPS, 

or the IM performance standard.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 162 of 567

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 

program, most recently for the pulp and paper industry category (40 CFR 430, 

promulgated in 1998). In these 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 12 month percent survival 

performance standard 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 

12 month impingement mortality performance standard by basing it 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 performance standard. Another four facilities 

demonstrated impingement mortality rates significantly greater than the performance 

standard of 24 percent, however, EPA notes these facilities were not required to optimize 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 163 of 567

their technology performance as part of their 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 12 month percent 

impingement mortality performance standard. By using the 12 month percent 

impingement mortality performance standard, EPA has ensured that the resulting 

performance 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 12 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 performance standard. EPA’s 

record includes approximately 250 total studies related to impingement (see TDD Exhibit 

11A-1).

Despite the overwhelming evidence that the 12 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 performance standard. EPA concluded that none of the alternatives were 

consistent with the need for facilities to demonstrate ongoing maintenance and operations 

 

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.”
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 164 of 567

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. Further, 

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 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 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 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 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 today’s final rule impingement performance 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 165 of 567

standard includes data that incorporate shellfish survival as part of the performance

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 12 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 12 month percent impingement mortality performance standard in the 

future. The 12 month percent impingement mortality performance standard requires that 

impingement mortality not exceed 24 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 Section 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 closed-cycle recirculating cooling 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 166 of 567

systems, a highly effective technology, because this technology is not available nationally

and therefore does not represent 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 Section VI.E.2 below 

and Chapter 6 of the TDD. EPA did not select the 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, 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 cycles-of-concentration, 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 167 of 567

respectively). These reductions in flow and the concurrent reductions in 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.

Under 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 comparable level to that achievable by

implementing a closed-cycle recirculating system as defined at § 125.92(c)(1).

 

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 recirculating system, as defined at § 125.92(c)(1).
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 168 of 567

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.

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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 169 of 567

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 

have auxiliary power consumption for fans. Therefore energy penalties and air 

emissions for tower operations can be minimized (though not eliminated). The 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 170 of 567

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.

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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 171 of 567

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.

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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 172 of 567

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 

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 closed-

 

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.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 173 of 567

cycle 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

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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 174 of 567

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. 

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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 175 of 567

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. 

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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 176 of 567

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 

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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 177 of 567

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 

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 

 

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.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 178 of 567

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 

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 

 

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. 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 179 of 567

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 

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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 180 of 567

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 

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.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 181 of 567

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 

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, 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 182 of 567

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 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. 

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.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 183 of 567

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. 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 

rule is based are available, feasible, demonstrated, and affordable for all regulated
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 184 of 567

facilities on a national basis. Moreover, EPA’s analysis showed that the difference in the 

total costs for the two options was nominal. Additionally, EPA notes that many facilities 

with a DIF under 50 mgd already use closed-cycle cooling and would have minimal 

burden under the final rule. 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.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 185 of 567

2. Proposal Option 2—Flexible Impingement 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. The constraints discussed above that are 

associated with retrofitting a large portion of the universe of affected facilities, led EPA 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 186 of 567

to conclude that requiring closed-cycle cooling on a uniform basis scale was not 

appropriate for a national regulation. 

EPA notes that it proposed multiple options that included closed-cycle, and 

solicited comment on all aspects of closed-cycle cooling. After fully considering all 

comments and data, EPA still finds closed-cycle cooling is not the “best technology

available for minimizing adverse environmental impact” required by section 316(b). 

Because of a combination of concerns over feasibility/availability, air emissions, and 

remaining useful life of the facility, EPA has rejected closed-cycle recirculating systems 

as the basis for national impingement and/or entrainment controls. Nor is EPA able to 

identify a subcategory for which these concerns no longer apply. 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 standards framework in today’s final rule will provide a consistent,

more efficient, and more effective approach 

than standards with an 

“off ramp.”
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 187 of 567

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 appropriate as 

BTA for entrainment.

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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 188 of 567

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).

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 manufacturing facilities) commented that EPA 

should adopt a site-specific approach to addressing impingement mortality, similar to that 

employed for entrainment. As a result, EPA also considered an approach that would have 

established both impingement mortality and entrainment requirements fully on a sitespecific 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, demonstrated, and 

affordable for facilities nationally. Because technologies are available, a fully sitespecific approach would place an unnecessary additional burden on state permitting 

resources. Moreover, the final impingement mortality standard includes several 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 189 of 567

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. 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 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 whose performance is comparable to or better than the technology

EPA concluded was the “best technology available” for impingement mortality

reductions: 

 Closed-cycle recirculating systems, defined at § 125.92(c)

 Existing offshore velocity caps, defined at § 125.92(v)
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 190 of 567

 Technologies that result in a design intake velocity less than or equal to 0.5 fps, 

including most modern cylindrical wedgewire screens

Although this rule leaves the BTA entrainment determination to the Director, with the 

possible BTA decisions ranging from no additional controls to closed-cycle recirculating 

systems plus additional controls as warranted, EPA expects that the Director, in the sitespecific 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.

G. Final Rule BTA Performance Standards 

The rule establishes the following BTA standards for Impingement Mortality and 

Entrainment: Impingement Mortality Standards at All Existing Units at Existing Facilities

that withdraw greater than 2 mgd DIF; an Entrainment Standard that requires site-specific 

entrainment controls determined by the Director for Existing Units at Existing Facilities

that withdraw over 2 mgd DIF; BTA standards for impingement mortality and

entrainment for new units at existing 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 provides 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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 191 of 567

technology available for impingement mortality reduction. But EPA is not requiring

compliance with the BTA impingement mortality standards only through monitoring data 

that 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 by employing any of seven alternatives, including monitored 

compliance with a numeric impingement mortality performance standard.

Based on its review of available data and information submitted by commenters, 

EPA identified a number of other technologies and operational measures that could 

achieve equivalent, or better, performance to the impingement mortality reductions 

achieved with modified traveling screens that may be available for some sites. Thus, the

final rule provides seven alternatives for complying with the BTA impingement mortality

standards. These include three compliance paths based on pre-approved technologies, and 

three compliance paths that offer a streamlined approach to compliance. EPA expects the 

majority of facilities will use one of these six options to comply with the BTA 

impingement mortality standards (see Exhibit VIII-1 for more information). 

The following pre-approved technologies will comply with today’s rule and are 

associated with minimal monitoring and reporting of operational and/or design 

parameters. These technologies are (the numbering reflects the numbering in §

125.94(c)): operating (1) a closed-cycle recirculating system; (2) a cooling water intake 

structure that EPA or the State NPDES permitting authority determines has a design

maximum through-screen intake velocity of 0.5 feet per second; or (4) an existing 

offshore velocity cap. The general intent behind a compliance path based on a pre-
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 192 of 567

approved technology is to provide a level of certainty to the regulated entity that they

would be deemed compliant with the relevant rule requirements by designing, installing, 

and operating the technology as specified in the regulation. The three pre-approved 

compliance alternatives are each based on a particular technology approach. The permit 

for each compliance alternative will necessarily include criteria, design standards, and 

operational conditions specific to the pre-approved technology. The compliance paths 

based on pre-approved technologies in today’s final rule include simplified permit 

application requirements (such as reduced or minimal study), documentation, or reduced

monitoring, and will therefore result in greatly simplified implementation. In today’s 

final rule, there are no biological compliance monitoring requirements for any of the 

three compliance paths based on pre-approved technologies. 

Under the 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 are (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 represents

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 BTA performance, a facility will need to conduct a two-year site-specific 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 193 of 567

study at the same time it conducts its source water characterization and Entrainment 

Characterization Study. This study must demonstrate that its modified traveling screens, 

or combination of technology controls and operational measures, have been adjusted and 

optimized so as to minimize impingement mortality. If the Director concludes that the 

facility has demonstrated optimized performance for its controls, the facility will have no 

subsequent biological monitoring and reporting requirements as compared to a facility

that complies using the impingement mortality performance standard. If the screens or 

other measures are not already installed, the Director may approve postponing the twoyear study to be conducted after the entrainment determination has been made. These 

three streamlined compliance alternatives are based on a technology or suite of 

technologies and practices with more variable performance, and as such necessitate some 

degree of study, in order to optimize technology performance for the 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 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 demonstrate 

compliance with the numeric impingement mortality performance standard through 

biological monitoring. Under this alternative, the owner or operator has the flexibility to 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 194 of 567

choose any technology, including a new or innovative technology, provided the 

compliance monitoring demonstrates the performance standard is achieved. 

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.

EPA does not have the data to determine precisely which impoundments are

serving as part of a closed-cycle recirculating system as defined at 40 CFR 125.92(c)(2). 

However, EPA is aware that some facilities have created their impoundments in a water 

of the U.S 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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 195 of 567

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 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 is including reductions in intake velocity as an alternative for complying

with the BTA impingement mortality standards through reduced intake velocity. A

facility choosing 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
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 196 of 567

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 facilities choosing this compliance 

alternative may not average intake velocity across multiple intakes.) In contrast to design 

flow above, a facility with an intake having a design through-screen intake velocity

greater than 0.5 fps may be operated at a reduced capacity and therefore may withdraw

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
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 197 of 567

A number of commenters stated that EPA should consider existing offshore 

intakes fitted with velocity caps to be pre-approved and complying with the BTA 

impingement mortality standards. Locating 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. These studies show that the impingement reduction performance of intakes 

submerged far offshore with velocity caps is dependent on site-specific conditions. The 

data show that solely locating an intake far offshore (i.e., without also employing a 

velocity cap) achieves a 60 to 73 percent reduction in impingement, and therefore does

not achieve impingement mortality reduction comparable to that of well-operated 

modified traveling screens. Similarly, the data also show 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, the combination of an existing intake located far offshore (i.e., 

approximately 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 12-

month average impingement mortality performance standard (alternative seven described 

 

85 The littoral zone extends from the shoreline to roughly the edge of the continental shelf.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 198 of 567

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 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 

 

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 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.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 199 of 567

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 

theperformance of its velocity caps is the best technology available for impingement 

reduction under the alternative found at § 122.95(c)(6). For more information, see DCN 

12-6601.

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 an option at §125.95(c)(5) for facilities that install 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 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 data collection, during which the facility will seek to 

optimize the technology performance to minimize impingement mortality. This study is 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 200 of 567

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, 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 

performance standard, by requiring facilities to study the conditions for optimized 

performance, many facilities will achieve impingement mortality reductions much greater 

than the 12-month average impingement mortality performance standard without 

significant additional investment. Biological data collection beyond this 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. If the Director 

concludes that the screens will achieve optimized performance, the Director will also 

incorporate operating conditions to ensure optimized performance as terms of the 

facility’s NPDES permit.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 201 of 567

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 

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 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 

 

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.

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.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 202 of 567

optimization study. As discussed earlier, the Director can establish interim measures as 

appropriate (40 CFR 125.94(b)). 

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 an approach where a single 

technology achieves the level of compliance necessary. Others may choose an approach 

of employing multiple technologies or operational measures, including reducing the 

number of organisms that are impinged or 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
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 203 of 567

 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 a BTA impingement mortality reduction performance at a particular 

site. As a result, EPA expects the reduction in impingement will be treated as an 

 

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.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 204 of 567

equivalent reduction in impingement mortality, and will therefore be considered by EPA 

or the State NPDES permitting authority in evaluating whether the chosen 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:
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 205 of 567

 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 data 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 

continues to operate below 24 percent of its intake capacity or continues to serve only 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 206 of 567

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. Comply with the Numeric Impingement Mortality Performance Standard

Facilities complying with the BTA impingement mortality standard by achieving

the numeric performance standard at § 125.94(c)(7) will perform monthly compliance 

monitoring to verify that the 12 month percent impingement mortality 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 Section 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 establishes a framework under 

which EPA or the State NPDES permitting authority must establish site-specific BTA 

entrainment requirements for each facility 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 34

percent reduction in total AEI. EPA 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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 207 of 567

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 site-specific analysis could be that the Director would 

determine that no other technologies beyond impingement controls are required for BTA

entrainment reductions, either because they are not feasible or because the social costs of 

additional control measures are not justified by the social benefits. 

In the case of site-specific entrainment controls for facilities withdrawing greater 

than 125 mgd AIF, the final rule requires facilities to also develop and submit an 

Entrainment 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. 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). 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 208 of 567

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 

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. 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 209 of 567

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 

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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 210 of 567

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 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;

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 VIII. The 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 211 of 567

final rule also requires peer review of the Comprehensive Technical Feasibility and Cost 

Evaluation Study, Benefits Valuation Study, and Non-Water 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 Federal, 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 

recirculating systems, fine-mesh screens with a mesh size of 2 mm or 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. The Director’s decision must include a written explanation that, at a minimum, 

includes 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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 212 of 567

feasibility of entrainment technology; (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 

thermal effects and water consumption.

In addition to the information required for development of impingement controls 

discussed above, the regulation also requires, in the case of facilities withdrawing greater 

than 125 mgd AIF, submission of certain other information for use in the site-specific

entrainment determination of BTA. The final rule also adds the permit application 

requirements at § 122.21(r) (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 above). 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 non-water quality environmental impacts of such controls, the 

monetized and nonmonetized benefits of such controls, and the presence of any

threatened and endangered species. 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, 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 213 of 567

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 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. 

H. Economic and Benefit Analysis for the Final Rule

1. Economic Justification for the Final Rule

Pursuant to the principles 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 $275 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 

652 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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 214 of 567

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 

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 which are not fully valued are often referred to as nonuse benefits – i.e., 

benefits that people derive apart from 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 was based on 

a species that represents less than one percent of adverse environmental impacts. EPA 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 215 of 567

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. EPA decided not to employ the survey results for 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 individuals 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 Other Options

As discussed above, EPA considered three other primary options before selecting 

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.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 216 of 567

Exhibit VI-1. Comparison of the primary options for 316(b) ($2011 millions at 2013, 3% discount rate)

Option Total Annualized Social Cost Monetized Benefits

Proposal Option 4 $251.8 $31.0

Final Rule $274.9 $32.8

Proposal Option 2 $3643.2 -$1542.6

I. 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 the best technology for reducing entrainment for a 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 217 of 567

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 the 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.

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 today’s rule but the existing requirements have been taken 

into account in costing..

For facilities that withdraw more than 125 mgd, the rule generally requires that 

the facility conduct an entrainment study as part of its permit application. The study will 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 218 of 567

indicate, at a minimum, the specific entrainment data 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. 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 entrainment 

study is important to provide corroboration of any through-facility 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 as 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, finemesh 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
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 219 of 567

 A discussion of the magnitude of water quality benefits, whether qualitative, 

quantitative or monetized, 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; 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 entrainment 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 entrainment study will identify species that might be entrained, and 

estimate their baseline entrainment rates given current entrainment controls. Moreover, 

the entrainment study will include information about the aquatic ecosystem effects of 

entrainment of species, 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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 220 of 567

will endeavor to identify high-quality examples of entrainment studies as they are 

completed, and post them to its website for this rule as a resource for study preparation.

EPA’s benefits estimates were based on an extrapolation of available literature on 

impingement and entrainment studies; the specific Entrainment 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 requirements 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 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 site-specific determinations when 

establishing entrainment controls.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 221 of 567

In the site-specific proceeding, the Director must 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 monetized, quantified, and qualitative 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 requires submission of 

additional information including, studies on entrainment at the facility, the costs and 

feasibility of control options, and information on the 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 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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 222 of 567

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 nonmonetized 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.

An aggregate evaluation of benefits (even if accurate) would not 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 flowweighted basis. Differences in species, life stages, and biological abundance across intake 

locations (even within a region) could lead to very different results for a site-specific 

analysis of a facility as compared to that facility’s share of national costs and benefits, 

even if the national results are, on average, accurate. A national assessment tends to mask 

variations in benefits and costs from different geographical locations for different 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.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 223 of 567

 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 ecological 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 factors that supported EPA’s determination not to establish a uniform national 

entrainment standard based on closed-cycle cooling. The Director also must base the 

determination about BTA controls on 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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 224 of 567

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.

This history illustrates the role that cost/benefit considerations have played. As 

early as 1977, EPA in a permitting decision and a General Counsel opinion 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 State 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. 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 this 

consideration to be applied at the permit level. This approach is consistent with the 

historical application of section 316(b) requirements 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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 225 of 567

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. As 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 analyzed possible additional costs associated with 

reductions in entrainment mortality that might result from the Directors’ determinations 

of site-specific BTA requirements. Because this process will play out over a number of 

years as Directors consider waterbody-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 are highly speculative. EPA is not presenting 

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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 226 of 567

required under the national BTA standard for entrainment. Without that refined 

information on a site-specific basis, EPA has no ability to predict Director decisionmaking 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 most effective technology for reducing entrainment, 

closed-cycle cooling, is not available to at least one quarter of all facilities because of 

geographic constraints, air permitting restrictions in a nonattainment area and remaining 

useful life of the facility. EPA has limited information on which facilities these are, 

despite the certainty that these 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 all 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.

 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 227 of 567

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 

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 (referred to as 

cooling ponds in the proposed rule). Commenters expressed confusion regarding the 

applicability of the proposed regulations because impoundments have both intakes from 

the impoundments and intakes that supply water to the impoundment. Many requested 

that EPA clarify that man-made impoundments, built to supply water for power plants, do 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 228 of 567

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 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 outside the scope of this rulemaking. However, today’s regulatory definition of 

closed-cycle 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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 229 of 567

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 

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 facilities 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.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 230 of 567

• 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.

• 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 includes the addition of a stand-alone unit that is constructed at an 

existing facility. 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 facilities 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 existing facility are subject to the requirements at 40 CFR 125.94(c) and 

(d).

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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 231 of 567

meet an alternative requirement at 40 CFR 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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 232 of 567

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 in the hundreds of billions, or is 1.9 billion on an age-one 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 233 of 567

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 the nonuse benefits 

transfer was based on a species that 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 respect to impingement

mortality, the rule provides seven compliance alternatives based on a set of widely used, 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 234 of 567

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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 235 of 567

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 proposed an impingement mortality 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 standards, some commenters interpreted the proposed rule as 

requiring this. EPA proposed impingement mortality standards that were expressed as a 

monthly average and a 12-month average. EPA recognizes, however, that some regulated 

entities might find a technology-based compliance option, rather than a performancebased approach, more attractive. Such an approach, particularly the specification of preapproved 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 technologies. Some commenters viewed the 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 236 of 567

proposed impingement mortality standard as overly 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 performance 

standard. Several industry stakeholders stated that, despite EPA’s best intentions, the 

proposed rule applied a one-size-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:

• Defining modified traveling screens as a pre-approved 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.

• Providing additional clarity on species of concern as it pertains to demonstrating 

compliance with the numeric impingement mortality performance standard.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 237 of 567

• Reevaluating the impingement mortality numerical 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 concerning how EPA determined the 

numeric impingement mortality performance standard. Additionally, see earlier

discussion 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:
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 238 of 567

• EPA should recognize the value of waterbody-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 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 waterbody-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 portions of days during a few months or 

less. Further, EPA found that some sites continue to withdraw water through their cooling 

water intake structure even when no power is being generated. 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 or operator may request that the Director establish 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 239 of 567

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)(3) states that mortality after passing the cooling 

water intake structure must be counted as 100 percent mortality unless you have 

demonstrated to the approval of the Director that the mortality for each species is less 

than 100 percent.

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 the

site-specific limitations at some facilities (e.g., blowdown water quality, scale, 

fouling problems).

• Cooling towers would result in significant adverse impacts from fine particulates, 

carbon dioxide emissions, evaporative water loss, and other issues.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 240 of 567

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 

or 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 most effective technology for reducing entrainment, EPA has 

not established BTA based on closed-cycle cooling because EPA concluded it was not 

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 requirements in terms of COC and comparable percentage flow reduction to qualify

as a closed-cycle recirculating system, 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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 241 of 567

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.

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.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 242 of 567

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 practicable. When the Director establishes a compliance schedule under § 125.94(d), 

the schedule must provide for compliance as soon as practicable. 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.

• 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
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 243 of 567

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.

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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 244 of 567

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-

6807). 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 12-6656.) 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 12-6656.) 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 

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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 245 of 567

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 IM compliance alternatives by either calculation or direct 

measurement. Compliance will be demonstrated through monitoring and reporting of 

actual or calculated intake velocities. Short-term exceedances of the velocity 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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 246 of 567

maximum velocity is not exceeded during minimum ambient source water surface 

elevations, as can be anticipated through best professional judgment 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 streamlined 

compliance alternatives in § 125.94 (c)(1) through (6) 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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 247 of 567

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)(11) 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 overly burdensome.

• Permit 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. Permit 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 

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 [INSERT date 45 months after 

effective date of final rule], the Director can delay submission requirements until such 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 248 of 567

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 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.

I. Endangered Species Act 

Some commenters argued that it is inappropriate to automatically treat T&E

species in a special category and provide for special consideration for them under the 

rule. These commenters asserted that EPA has no basis for incorporating ESA

requirements into the rule and addressing ESA species under the NPDES program; they

argued that the ESA operates independently. Other commenters argued that EPA has an
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 249 of 567

obligation under the ESA to consult with the Services if cooling water intake structures 

are likely to affect threatened or endangered species.

Response: EPA has addressed T&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). Section 7 of the Endangered Species Act states that “each 

Federal agency shall, in consultation with and with the assistance of [the services] insure

that any action authorized, funded, or carried out by [the agency]... is not likely to 

jeopardize the continued existence of any threatened or endangered species or result in 

the destruction or adverse modification of [designated critical] habitat.” Under CWA 

section 316(b), facilities subject to NPDES permitting that have cooling water intake 

structures are subject to BTA to minimize adverse environmental impacts. The final rule 

requires NPDES 316(b) permittees to identify all Federally-listed threatened and

endangered species and/or designated critical habitat that are or may be present in the 

action 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 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.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 250 of 567

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 

per second. For details about the scope and applicability of today’s final rule, see Section

I above.

Today’s final rule (as described in Section 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 and entrainment standards at § 125.94(e).
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 251 of 567

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 publication]. The 

requirements in this rule will then be implemented in NPDES permits as the permits are 

issued.

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 [INSERT date 45
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 252 of 567

months after effective date of final rule], under § 125.95 a facility may request that the 

Director waive 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. Third, in the case of permit proceedings begun prior to the effective date of 

today’s rule, and issued prior to [INSERT date 45 months after effective date of final 

rule], the Director should proceed. See §§ 125.95(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 submit 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 In 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

 

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.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 253 of 567

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). Fourth, in permit applications subsequent to the first 

permit issued under § 125.94(a)(1) with all 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 waterbody remain substantially unchanged since the 

previous application.93 See § 125.95(c). In addition to all of these flexibilities, today’s 

final rule gives advance notice to affected facilities about 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 

 

93 However, if conditions at the facility or in the waterbody 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.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 254 of 567

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, 

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
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 255 of 567

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 

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 so 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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 256 of 567

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). It would then be appropriate for the Director to

develop a schedule whereby the facility would proceed to design, construct, and 

implement its technologies for impingement mortality, for entrainment, or for both 

together should the same technology addresses both impacts. In this manner, the EPA has 

harmonized 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 practicable according to the schedule of requirements set by the 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 257 of 567

Director. The concept of 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 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 services to orderly, functioning markets. It is appropriate for the Director to

take this into account when establishing a deadline for compliance. Any 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 comply with the impingement mortality standard 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(h), to establish 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 258 of 567

interim BTA requirements in a facility’s schedule of requirements, for impingement 

mortality, entrainment, or both, where necessary on a site-specific basis.

In contrast to the proposed rule, today’s final rule does not include a requirement 

for compliance with the impingement mortality standards within eight years. EPA 

expects, however, that the final rule will generally result in compliance within a similar 

period of time. The combination of permit issuance, 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 that 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
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 259 of 567

may, under 40 CFR 122.21(g)(13), request additional information including any permit 

application requirements in § 122.21(r).

B. How Does 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

Data, impingement technology performance optimization study, Entrainment 

Characterization Study, and where applicable, entrainment 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'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 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 systemc 307 18%

Design velocity 362 21%

Actual velocity 226 13%

Existing offshore velocity capc10 1%

Modified traveling screens 488 29%

System of technologies 278 17%

Impingement Mortality Performance Standard 12 0.7%

De minimis **b **b

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. 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 260 of 567

b. EPA has not estimated which facilities will be determined to be “de minimis” under § 125.94(c)(11) 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 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 waterbody 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 corresponding 

biological performance evaluations would be conducted approximately every five years.

 

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.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 261 of 567

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) is described in more detail below. The final rule requires existing facilities to 

prepare and submit some 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)(5) 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).

All existing facilities are required to complete and submit permit application 

studies to describe the source waterbody (§ 122.21(r)(2)), cooling water intake structures 

(§ 122.21(r)(3)), characterize the biological community in the vicinity of the cooling 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 262 of 567

water intake structure (§ 122.21(r)(4)), cooling water system (§ 122.21(r)(5)), and 

operational status (§ 122.21(r)(8)). Facilities 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 

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 § 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 263 of 567

125.94(c)(1), (2), and (4) include pre-approved technologies, the owner or operator of a 

facility choosing one of these three 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 three 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 data collection that in most cases 

would occur during the same two year period of 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 three 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 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 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 

 

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.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 264 of 567

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.

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 § 122.21(r)(9), Entrainment Characterization Study; § 

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

Environmental and Other Impacts Assessment. As with the biological data collection

required of some facilities under § 122.21(r)(6), EPA expects biological data 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). EPA notes that facilities 

below the 125 mgd threshold are not automatically exempt from entrainment 

 

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.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 265 of 567

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); 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 data 

collection for the required Entrainment Characterization Study at § 122.21(r)(9). 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 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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 266 of 567

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, 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.

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 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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 267 of 567

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 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).

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
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 268 of 567

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 

Performance 

Standard

Yes Yes Yes Yes Yes Maybe Maybe Yes

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

Yes Yes Var.a Var.a Var.a Var.a Var.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, 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). The Director may find aspects of the permit application requirements to 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 269 of 567

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 

waterbody 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 waterbody type where each cooling water intake structure is located; 

identification and characterization of the source waterbody’s hydrological and 

geomorphological features, and the methods used to conduct any physical studies to 

determine the intake’s area of influence in the waterbody 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 

 

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.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 270 of 567

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 

submit a narrative description of the configuration of each of cooling water intake 

structure and where it is in the waterbody 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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 271 of 567

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 and those species most important in terms of significance to commercial 

and recreational fisheries. In addition, the applicant must 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. 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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 272 of 567

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 waterbody. The study area should 

include, at a minimum, the area of influence of the cooling water intake structure. 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 item (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 standards of the rule. The definition for 

“fragile species” at § 125.92 is a species of fish or shellfish that has an impingement 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 273 of 567

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 final rule. Further, EPA is providing examples, in the list of 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 are specifically identified in the TDD Chapter 11 as 

examples of species that may be, at the Director’s discretion, excluded from performance 

standards 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 die-off when 

the water temperature 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 mortality allows the Director to establish site-specific controls under §

125.94(c)(9) to address fragile species.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 274 of 567

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 

cooling water reused as process water, process water reused for cooling, and the use of 

gray water for cooling); description of reductions in total water withdrawals including 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 275 of 567

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 waterbody 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. 

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 standards. The facility must 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 276 of 567

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 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 data 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 

data 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 would require at least 

one year worth of 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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 277 of 567

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 data 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 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 

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 

 

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.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 278 of 567

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 level 

of performance for impingement mortality has 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 impingement 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 §

122.21(r)(6)(ii). The site-specific study must provide a description of the technologies, 

operational measures, or sampling 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 data collection, as just described.

The EPA is aware that it is possible for a facility to reduce its rate of 

impingement, but the same number of impinged fish die. This has the unintended 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 279 of 567

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 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 

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 waterbody. 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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 280 of 567

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 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 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 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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 281 of 567

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 

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, throughfacility entrainment survival (distinguished for eggs and larvae), entrainment analyses, or

 

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), (2) or (4). 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 282 of 567

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 

waterbody 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.

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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 283 of 567

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)(12) to 

document infrequently used power generating units that operate 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) 

through (c)(7). With respect to entrainment, the BTA for entrainment is determined by 

the Director for each site, and 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 data collection. EPA envisions the 

facility would extend 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 data 

collection period and frequency of entrainment characterization, and an identification of 

the organisms sampled to the lowest taxon possible. The data collection must be 

representative of the entrainment at each intake, and the study must document how the 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 284 of 567

location of the intake in the waterbody and the water column are accounted for. The study

must document the intake flows associated with the data collection. Consistent with the 

permit application requirements requiring biological data 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 with 

documentation regarding the continued relevance of the data. The study must include 

analysis of the 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 will 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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 285 of 567

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 2 mm or smaller, reuse of water or alternate 

sources of cooling water, and any other entrainment reduction technologies identified by 

the applicant or requested by the Director. 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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 286 of 567

within the facility or from other dischargers in the vicinity. 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 closedcycle system, the significant reduction in flow may make nearby alternative sources more 

feasible. This analysis should include an estimate of the cost to 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
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 287 of 567

a facility, but rather 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 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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 288 of 567

implementing each candidate technology while meeting all regulatory and operational 

requirements of the facility. 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 obtain peer 

review of the Comprehensive Technical Feasibility and Cost Evaluation Study, as 

described in Section 12.

10. § 122.21(r)(11) Benefits Valuation Study

The owner or operator of the facility must submit a detailed discussion of the 

benefits of the candidate entrainment reduction technologies evaluated in § 122.21(r)(10)

and using data in the Entrainment Characterization Study in § 122.21(r)(9). 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 for all exposed life stages, estimation of 

changes in stock and harvest levels of commercial and recreational 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

increased 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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 289 of 567

already completed and how these have affected fish abundance and ecosystem viability in 

the intake structure’s area of 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 Section 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 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.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 290 of 567

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 § 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 291 of 567

122.21(r)(9), because this data would be included in the Comprehensive Technical 

Feasibility and Cost Evaluation Study, Benefits Valuation Study, and Non-Water 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.

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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 292 of 567

complies with BTA standards for entrainment at § 125.94(e)(1) by reducing 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 Study at § 122.21(r)(9). The Director may determine 

additional data and information, including data collection, is necessary to make the 

demonstration.

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 

 

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)(1are 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.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 293 of 567

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 (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 data 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 [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 

application requirements. EPA notes that the Director has the discretion to require 

additional studies, data 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.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 294 of 567

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 

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 data 

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.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 295 of 567

In permit terms subsequent to the first permit issued under the final rule, the 

facility will re-submit the § 122.21(r) permit application studies, while the rule still 

includes two years of biological data 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 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 data 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 waterbody remain substantially unchanged since the previous 

permit application.

101 EPA expects the Director would assess the relevant previously

submitted information and determine whether 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.

 

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 

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.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 296 of 567

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 to 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.

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:

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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 297 of 567

and considered by the Director in making that determination, under § 125.98(g) 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 data collection

requirements, study requirements, and schedules in recently issued permits.

b. If the Director establishes a compliance schedule under § 125.94, the 

Director will establish a schedule that sets requirements as soon as 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) will be 

used, or could otherwise affect a facility’s choice of technology, to meet the 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 10-6860 for information on the approach 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 298 of 567

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.

c. The Director will review the permit application materials and studies 

submitted under § 122.21(r) and determine which entrainment controls are appropriate.

Factors that must be considered and factors that may be considered in making the 

determination are provided at § 125.98. The Director must 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 

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. 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). 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 299 of 567

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.

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 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, 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 300 of 567

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, etc.) minus any savings 

associated with downtime. If they are considered in the social costs analysis, downtime

costs must be adjusted to reflect production made up by other facilities or firms, 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 

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. EPA is 

using energy penalty to mean only 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 cost 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, 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 301 of 567

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 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, 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. 

This includes additional permitting or reporting expenses, or both. For social 

costs, the estimate should include the costs to the facility and those expected to be 

incurred by the Director.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 302 of 567

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 

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 categories, including

increased harvest for commercial fisheries, increased use values for recreational fisheries, 

and nonuse 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 nonuse values. Otherwise, nonuse values should be evaluated 

quantitatively and/or qualitatively. Quantitative analysis, even without monetization, can 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 303 of 567

be quite useful in evaluating nonuse 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 

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.

Nonuse benefits, which encompass existence and bequest values, include impacts 

in such areas as population resilience and support, nutrient cycling, natural species 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 304 of 567

assemblages, and ecosystem health and integrity. Nonuse 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 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. This

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, OMB

recommends that Federal 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 must be considered in

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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 305 of 567

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 should document the basis for such a determination and include it in 

the public notice for the draft permit.

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 three compliance alternatives 

based on pre-approved technologies or one of the three 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.

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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 306 of 567

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 

comment, and the Director’s response to any comment on this determination must be 

included in the record for the final permit. 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 data collection to 

demonstrate support for a de minimis level of impingement. In addition, EPA does not 

expect that a de minimis exemption would apply to facilities with no technology present 

other than trash racks, 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 for an aquatic life use, 

the waters are not attaining a designated use, and there would be more than minor 

detrimental effects on threatened or endangered species 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 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 each site, EPA concluded that 

specific regulatory language for de minimis entrainment was unnecessary.

5. Low Capacity Utilization Units
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 307 of 567

The Director may consider less stringent controls for intakes dedicated to low 

capacity utilization rate (CUR) power generating units. 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 averaged 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). When 

determining the permit’s IM requirements associated with the low CUR unit, the Director 

may consider, after conferring with any appropriate state co-regulators (such as public 

utility commissioners) and 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.

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:
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 308 of 567

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

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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 309 of 567

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). 

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), detailed biological data 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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 310 of 567

§ 125.95 (d) (i.e., permit application and supporting information requirements) and § 

125.96 (c) (i.e., additional monitoring requirements).

7. Nuclear Units

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 practicable 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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 311 of 567

because the specific method of compliance with the BTA standards for impingement 

mortality is tied to the determination of BTA requirements for entrainment. Further 

discussion of this alignment of compliance deadlines is provided in Section A. 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 need to submit (r)(9) through (13), if it exceeds 125 

mgd AIF and these requirements are not waived by the Director. The information still 

required at (r)(2) to (8) is considerably less burdensome. The monitoring must be 

representative of normal operating conditions, and must include measuring cooling water 

withdrawals, make-up water, and blowdown 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 closed-cycle cooling are not subject to biological 

compliance monitoring unless otherwise specified by the Director (see § 125.96(c)).
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 312 of 567

2. 0.5 Feet per Second 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 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 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.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 313 of 567

3. 0.5 Feet per Second Through-screen Actual Velocity

This method of compliance is similar to the design velocity alternative 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 area. 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.

Under today’s final rule, the Director may authorize the facility to exceed the low 

velocity compliance alternative for brief periods for the purpose of maintaining the 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 314 of 567

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 800 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 and

trigger an avoidance response by fish and other aquatic organisms. Intake flow must be 

monitored at a minimum frequency of daily. This information will 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 would 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 Standard).
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 315 of 567

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 consistently be able to meet the impingement mortality performance 

standard. If EPA were to simply set a performance standard based on the numeric 

performance levels achievable by modified traveling screens, a facility would have to 

conduct continual biological monitoring to demonstrate compliance. A far more efficient 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 316 of 567

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 data collection and studies required in the 

permit application at § 122.21(r)(4) and (6)(i), including an impingement technology 

performance optimization study. Biological data collection should follow the sampling

protocols described in section7 below.

The optimized operation documented by the impingement technology 

performance optimization study will result in more than just meeting the impingement 

mortality standard, and results in a facility achieving the best possible performance.102

The biological data 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 condition to assure proper functioning of 

the technology. As long as the permit conditions are met, the EPA does not expect any

 

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 

performance 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.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 317 of 567

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 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 data 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 the facility’s system to a once-through cooling system 

with a traveling screen whose point of withdrawal from the surface water source is 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 318 of 567

located at the shoreline of the source waterbody. 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 data collection

demonstrating the rate of impingement resulting from the system. For this demonstration, 

data collection must be conducted no less frequently than monthly. The Director may

establish more frequent data 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 data collection demonstrating the level of impingement mortality the optimized 

system achieves. Biological data collection must be representative of the impingement 

and the impingement mortality at the intakes and should follow the sampling protocols 

described in section 7 below. The impingement technology performance optimization 

study must provide a description of any sampling approach used in measuring 

impingement mortality, including a taxonomic identification to the lowest taxon possible 

of all organisms to be sampled; 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 waterbody and the water column are accounted for in the 

sampling locations. EPA requires the entrapment of organisms, as 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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 319 of 567

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

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 

 

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.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 320 of 567

Director’s decision will be informed by comparing the impingement mortality data under 

§ 122.21(r)(6)(ii) to the impingement mortality performance 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 

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 

 

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.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 321 of 567

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 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 data 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 

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)
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 322 of 567

= (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 

technology for all facilities. EPA expects a facility will use the required two years’ worth

of monthly biological data collection and studies to conduct a similar analysis for each 

month. The minimum required data collection and studies will result in annual average 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 323 of 567

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 standard at § 125.94(c)(7) by

demonstrating a 12-month average mortality of 24 percent or less. The 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 nonfragile organisms that are collected or retained on sieve with a maximum spacing of 0.56 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 324 of 567

inches (i.e., that are impinged [I]), and the number that die 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(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 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 12-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 over 

the same 12 months, as shown by the following equation:

%  = 





 × 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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 325 of 567

monthly (or more frequently) and reporting that data in their discharge monitoring 

reports, facilities are not required to meet a monthly impingement mortality 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 12-month average performance standard, it will be deemed to be in

compliance with the 12-month average performance 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 waterbody. However, for ease of sampling and 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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 326 of 567

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 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 

 

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.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 327 of 567

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 performance 

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 

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.

 

108 For a discussion of how EPA has changed its view of screen mesh size, see Section 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; 

the performance standard may be applied differently at facilities with smaller mesh size. Therefore, these 

standards 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.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 328 of 567

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 waterbody 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 waterbody and any changes in the biology of the 

waterbody. 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 data 

collection to the minimum required by the permit application at § 122.21(r) and any 

monitoring the Director determines to be appropriate for verifying permit operating 

conditions.

8. 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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 329 of 567

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

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.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 330 of 567

G. What Monitoring is Required for Entrainment?

Where 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(h), and any more stringent standards under § 125.94(i).

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 

Section F. Such measures will be used to document that the facility has minimized makeup and blowdown flows.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 331 of 567

For facilities complying under § 125.94(e)(2), the frequency of monitoring will be 

determined by the Director and 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 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 12-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 a 12-month average can be calculated.

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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 332 of 567

for calculating impingement must be the same sieve used for calculating entrainment, so 

all organisms are 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 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 recirculating system (ECCRS) 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:

ECCRS = (EB) × (100 – 97.5) ÷ 100

The resulting value, ECCRS, 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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 333 of 567

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 × 106organisms per day

The maximum entrainment mortality for a closed-cycle cooling system is thus

ECCRS = (EB) × (100 – 97.5) ÷ 100

= (48 × 106organisms per day) × (100 – 97.5) ÷ 100

= 1.2 × 106organisms 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

= (48 × 106organisms per day) × (100 – (97.5 x .9)) ÷ 100

= 5.88 × 106organisms per day.

 

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).”
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 334 of 567

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 (h), and any more stringent standards under § 125.94(i).

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 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).

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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 335 of 567

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 125.97(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(b) 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, 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 

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.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 336 of 567

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 section 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 Will 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 

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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 337 of 567

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.

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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 338 of 567

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. Protection of Endangered and Threatened Species and Designated Critical 

Habitat

1. Existing 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 

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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 339 of 567

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. 

2. EPA’s 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. 1535(a)(2). In the case of any Federal agency action subject to 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 340 of 567

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. 

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. 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 341 of 567

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 

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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 342 of 567

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 

permit requirements and conditions. EPA noted that its existing NPDES permitting 

regulations reference a number of Federal laws that might apply to Federally-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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 343 of 567

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 

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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 344 of 567

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 

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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 345 of 567

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 

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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 346 of 567

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 

of its CWA authority to object to a permit where EPA finds that issuance of 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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 347 of 567

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 

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 (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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 348 of 567

minor changes, as described in the Services’ regulations and Handbook, EPA does not 

expect that installation of closed-cycle 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.

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 

Federally-listed threatened and endangered species. In addition, under § 125.96(g) 

(additional monitoring requirements) and § 125.97(g) (additional reporting 

requirements),where the Director requires additional measures to 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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 349 of 567

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 Services 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 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. 

EPA’s commitment to coordinate effectively with the Services includes following 

the procedures in section IX.A.6 and 7 of the MOA:

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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 350 of 567

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 

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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 351 of 567

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)).

The grounds for EPA’s exercise of its discretionary authority to object to State or 

Tribal permits are described in the NPDES regulations at 40 C.F.R. § 123.44. 

These include that the proposed permit fails 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 demonstrate that the permit 

will ensure compliance with applicable requirements. See 40 C.F.R. § 

123.44(c)(1). 

If EPA objects 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 not 

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 structures. Moreover, section 316(b) of the CWA accords EPA 

broad authority to protect waters of the United States from adverse environmental 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 352 of 567

impacts associated with cooling water intake structures, including adverse effects to 

Federally-listed 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, 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 and endangered 

species and critical habitat and include appropriate protections in NPDES permits, insures 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 353 of 567

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.

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. 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. 

IX. Cost Development and Economic Impact Analysis

This section summarizes EPA’s analysis of the social cost and economic impact 

for three regulatory options. In addition to today’s rule, referred to as the Final Rule, EPA 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 354 of 567

analyzed two other options similar to those options at proposal (see section VI.D Other 

Options Considered for Today’s Final Regulation for more context). The regulatory

options can be described as follows:

 Final Rule: Flexible impingement mortality performance standard for 

existing units based on modified traveling screens with fish returns for all 

facilities with DIF greater than 2 mgd, closed-cycle cooling or its 

equivalent for new units for impingement and entrainment, and a national 

BTA standard that requires a site 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 DIF greater than 2 mgd, and 

closed-cycle cooling or its equivalent for new units; and 

 Proposal Option 4: Flexible impingement mortality limitations based on 

modified traveling screens for all facilities with DIF 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 for

impingement mortality controls at facilities with flow less than or equal to 

50 mgd.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 355 of 567

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

In estimating the total cost 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, will not incur costs to retrofit new 

technologies. These facilities, including those in New York and California, will still incur 

permitting costs. EPA has established that existing closed-cycle recirculating systems 

will comply with the impingement BTA requirements.

For the economic analysis, 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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 356 of 567

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 regulated 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.

In the economic analysis, EPA accounted for these costs on an as-incurred basis. 

They are reported 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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 357 of 567

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 

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.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 358 of 567

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 

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 Section 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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 359 of 567

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 

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 

 

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.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 360 of 567

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 

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 

 

112

 A refinery, for example, may have dozens of heat exchange processes throughout the facility, including 

a mix of wet and dry non-contact cooling equipment. 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 361 of 567

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 12-6650 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.

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 

 

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.

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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 362 of 567

VI of this preamble, a facility may also comply with impingement mortality requirements 

by meeting a low velocity compliance 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 compliance 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 of the intakes as a cost component for 

the “systems” approach to compliance with the IM standards.

EPA also analyzed the costs of those options associated with entrainment 

requirements based on wet cooling systems. 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 

 

technologies may also be capable of meeting the final rule requirements; however, these technologies are 

not available at all facilities.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 363 of 567

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 

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 facilities and 15 years for nuclear facilities, 

 

116 Nuclear Energy Institute reported average length of outage from 2003 to 2009.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 364 of 567

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 

installation downtime for retrofitting to closed-cycle cooling for non-nuclear electric 

generators is 4 weeks. This total downtime allows for the tie-in of the closed-cycle 

system to the existing cooling water system. The refueling outage downtime, the safetysensitive 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 

 

117 EPA’s data shows that facilities have an average of 4 to 5 bays.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 365 of 567

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 energy 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 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 closed-cycle 

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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 366 of 567

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.

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 method 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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 367 of 567

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 6. 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 Chapters 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 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.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 368 of 567

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 three groups for 316(b) compliance purposes: 1) subject to the Phase I 

rule,119 2) 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 3) subject to today’s 

rule and projected to incur compliance costs. Exhibit IX-1 presents the estimated total 

new capacity and the estimated capacity for new stand-alone units.

Exhibit IX-1

Fuel Type

Total Including Phase I Existing Facility New Units Only

New Capacity Stand-Alone

MW MW

Fossil Fuel 295 80

Combined Cycle 3,264 147

Total 3,559 227

 

118 Capacity increases include considerations for fuel type. 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 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 these data EPA assumed that 75

percent to 90 percent of new units will be designed with a closed-cycle recirculating cooling system 

regardless of the requirements of today’s rule. See DCN 12-6672. As a result, this category of new capacity 

was not assigned any compliance costs.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 369 of 567

Costs for closed-cycle cooling are assigned to a portion of new stand-alone units, as 

shown the generating capacities in Exhibit IX-3.

Exhibit IX-3

Fuel Type

Annual Only 24-year Total Only

Stand-Alone Stand-Alone

MW MW

Fossil Fuel 8 191

Combined Cycle 15 353

Total 23 544

EPA then estimated the total costs for the third 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 unit provisions of today’s rule. These costs include capital121 and O&M costs, as 

 

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.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 370 of 567

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

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 facilities with multiple industrial processes, leads EPA to 

conclude that facilities installing new units at existing manufacturers will comply with 

the new unit 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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 371 of 567

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.

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 the

Federal government to administer the rule. These costs are the opportunity costs to 

 

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.

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. 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 372 of 567

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

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 assumes 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 technologyinstallation 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 

 

124 EPA conducted the cost and economic impact analyses on a calendar-year basis. For these analyses, 

EPA used calendar year 2013 as the promulgation year of today’s rule and 2014 as the first postpromulgation 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.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 373 of 567

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

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 

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 reinstallation 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

 

125 For this analysis, EPA assumed that the last year of technology installation for all regulated facilities

under any of the regulatory options—i.e., 2030—is also the first year of steady-state compliance with 

regulatory requirements.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 374 of 567

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. 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 analyzed costs 

incurred by State and Federal governments for administering the regulation on a yearexplicit 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 $272

million for the existing unit provision of today’s rule, $252 million for Proposal Option 4, 

and $3,643 million for Proposal Option 2. At the 7 percent discount rate, these costs are 

$295 million for today’s rule, $272 million for Proposal Option 4, and $3,583 million for 

Proposal Option 2.126 See the EA (Chapter 7) for an explanation of why the annualized 

 

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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 375 of 567

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 facilities (as opposed to administrative costs estimated

for States and the 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).

Compliance costs estimated for electric generators account for the largest 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

 

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.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 376 of 567

million, $0.4 million under Proposal Option 4, and $6 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 $0.4 million under Proposal 

Option 2.128 EPA’s analysis found a similar profile of per facility costs using the 7 

percent discount rate (see EA Chapter 7 for additional detail). EPA’s estimate of Federal 

and State government costs for administering this rule is small in relation to the estimated 

direct cost of regulatory compliance. EPA estimates $1 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 $202.9 $203.7 $3,413.3

Manufacturers $47.8 $67.7 $229.2

Total Direct Compliance Cost $250.7 $271.4 $3,642.5

State and Federal Administrative Costs $1.0 $1.0 $0.7

Total Social Costs $251.8 $272.4 $3,643.2

Using 7 percent discount rate

Direct Compliance Cost:

Electric Generators $219.2 $220.0 $3,339.3

 

127 Calculated by dividing direct compliance costs for each type of facility by the total of 544 electric 

generators subject to today’s rule on the basis of facility count-based weights (see EA Appendix H).

128 Calculated using the total of 521 manufacturers subject to today’s rule on the basis of technical weights 

(see EA Appendix H).
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 377 of 567

Proposal Option 4 Final Rule Proposal Option 2

Manufacturers $51.9 $74.2 $243.0

Total Direct Compliance Cost $271.1 $294.3 $3,582.3

State and Federal Administrative Costs $1.0 $1.0 $0.7

Total Social Costs $272.1 $295.3 $3,583.0

a Cost estimates exclude costs associated with baseline closure facilities.

EPA also estimated the cost for installing closed-cycle recirculating 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 unit provision of the final rule will result in an 

annualized cost of $2.5 million and $2.0 million using 3 percent and 7 percent discount 

rates, respectively, including compliance costs to facilities and administrative costs to

States and Federal government.

The Agency estimated that at a 3 percent discount rate, the total social cost of the 

final rule, including the existing and new unit provisions, will be $275 million. At a 7 

percent discount rate, this cost is $297 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 $2.5 $2.0

Existing Units $272.4 $295.3

Existing and New Units $274.9 $297.3

a Cost estimates exclude costs associated with baseline closure facilities.

b Values may not add due to rounding.

D. Economic Impacts

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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 378 of 567

conducted separate analyses for electric generators and manufacturers 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 used compliance cost estimates from the EPA 

engineering analysis (see TDD 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 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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 379 of 567

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.

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

i. 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 

 

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 assumed either to have already retired their steam operations or expected to do so in the 

future.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 380 of 567

cost-to-revenue thresholds of 1 and 3 percent to categorize facilities according the 

potential economic impact of the rule. EPA concludes that facilities incurring costs below 

1 percent of revenue will not face significant economic impacts, while facilities with 

costs of at least 1 percent but less than 3 percent of revenue have a chance of facing 

economic impacts, and 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, 86 percent of regulated facilities will incur compliance costs of less than 1 

percent of revenue. Under Proposal Option 4, 87 percent of regulated facilities would 

also incur costs of less than 1 percent of revenue. EPA estimates that Proposal Option 2 

would result in 42 percent of facilities incurring costs exceeding 1 percent of revenue, 

and 43 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 4 475 87.4% 35 6.5% 31 5.7%

Final Rule 470 86.5% 40 7.4% 31 5.7%

Proposal Option 2 228 41.9% 79 14.5% 235 43.2%

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 339 facilities (542 on a weighted basis). For more 

information on facility sample weights see EA Appendix H.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 381 of 567

ii. 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 are 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) facility-level weights, but 

without entity-level weights and (2) 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 

approaches. EPA estimates that between 123 and 159 entities own regulated facilities. 

Further, the Agency estimates that between 91 and 94 percent of parent entities will incur 

annualized costs of less than 1 percent of revenues under the final rule. This finding also 

holds under the two other options EPA considered, with between 91 and 94 percent of 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 382 of 567

entities incurring costs of less than 1 percent of revenue under Proposal Option 4 and 

between 70 and 78 percent under Proposal Option 2.

Exhibit IX-7. Entity-level cost-to-revenue analysis resultsb

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 4 123 112 91.1% 3 2.4% 0 0.0% 8 6.5%

Final Rule 123 112 91.1% 3 2.4% 0 0.0% 8 6.5%

Proposal Option 2 123 86 69.9% 17 13.8% 12 9.8% 8 6.5%

Using Entity-Level Weights

Proposal Option 4 159 150 94.2% 0 0.0% 0 0.0% 9 5.8%

Final Rule 159 150 94.2% 0 0.0% 0 0.0% 9 5.8%

Proposal Option 2 159 124 78.1% 18 11.6% 7 4.4% 9 5.8%

a EPA was unable to determine revenues for 8 parent entities (9 weighted).

b This analysis assumes no cost pass-through to electricity consumers.

b. 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, these 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 from the perspective of electricity

consumers. Facilities that are merchant providers can pass along costs only to the degree 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 383 of 567

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 passthrough 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.a.1, should not be combined. EPA 

conducted this analysis for 544 electric generators.

i. 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.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 384 of 567

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 unit provision of the final rule, 

annualized compliance costs (in cents per kWh sales) range from nearly $0.00 in the 

WECC region to $0.040 in the HICC region. EPA reached the same findings for Proposal 

Option 4. Under Proposal Option 2, costs range from $0.00 in the WECC region to 

$0.351 in the HICC region. On average, across the United States, the final rule and 

Proposal Option 4 result in a cost of $0.009 per kWh, while Proposal Option 2 results in a 

higher cost of $0.155 per kWh.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 385 of 567

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 0.014 0.014 0.171

HICC 0.040 0.040 0.351

MRO 0.010 0.010 0.174

NPCC 0.008 0.008 0.126

RFC 0.011 0.011 0.200

SERC 0.013 0.013 0.219

SPP 0.009 0.009 0.078

TRE 0.008 0.008 0.206

WECC 0.000 0.000 0.000

United States 0.009 0.009 0.155

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.

ii. 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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 386 of 567

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 unit provision of the final rule, 

the average annual cost per residential household varies across NERC regions, ranging 

from $0.01 in WECC to $2.82 in HICC. EPA reached the same findings 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 $31.72 in SERC. EPA 

estimated that on average, for a typical U.S. household, the final rule will result in an 

annual cost of $1.03 in higher electricity rates per household. EPA estimates that this cost 

would be $1.03 per household under Proposal Option 4 and $17.23 per household under 

Proposal Option 2.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 387 of 567

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 $1.91 $1.91 $23.15

HICC $2.82 $2.82 $24.61

MRO $0.99 $1.02 $18.10

NPCC $0.61 $0.62 $9.52

RFC $1.10 $1.10 $20.64

SERC $1.96 $1.96 $31.72

SPP $1.30 $1.30 $10.71

TRE $1.15 $1.15 $30.59

WECC $0.01 $0.01 $0.01 

United States $1.03 $1.03 $17.23

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 owner 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.

c. Barrier-to-Development Analysis – New Unit Provision of the Final Rule
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 388 of 567

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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 389 of 567

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 the analyses for the previous 316(b) regulations, including the proposed rule,

EPA used the Integrated Planning Model (IPM®),

132 a comprehensive electricity market 

optimization model, to assess the economic impact of regulatory options within the 

context of regional and national electricity markets. 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 

units in supplying power to the electric transmission grid. Increases in electricity

production costs and potential reductions in electricity output at regulated facilities – due 

to the temporary shutdown of existing electric generating units during technology

 

132 Developed by ICF, Inc.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 390 of 567

installation – 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 regulated 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.

The 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 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

 

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.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 391 of 567

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 

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 

 

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

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 392 of 567

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 

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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 393 of 567

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 

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, 

 

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.

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.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 394 of 567

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 

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 

 

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.

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***

Page 395 of 567

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 

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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 396 of 567

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 

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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 397 of 567

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 

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. For three out of eight NERC regions, electricity prices decline slightly

 

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.

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 398 of 567

– by no more than $0.05 per MWh (0.1 percent) in TRE. Electricity prices increase in the 

remaining five NERC regions, with the largest increase, $0.29 per MWh (0.4 percent), 

occurring in NPCC. These very small estimated changes in electricity prices are 

essentially within the analytic “noise” of the electricity market modeling system.

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)

Net Changes in Early 

Retirements

Changes in Variable Costs Changes in Total Costs

GW

% of 

Total 

Baseline

Capacity 

$2011/MWh % of Baseline Mill 2011$

% of 

Baseline

FRCC 68 0 0.30% -$0.03 -0.10% $51 0.30%

MRO 76 0 0.00% $0.01 0.10% $62 0.40%

NPCC 73 0 0.50% $0.00 0.00% $28 0.20%

RFC 237 0 0.10% $0.01 0.00% $157 0.30%

SERC 274 0 0.10% $0.02 0.10% $182 0.30%

SPP 59 -1 -1.50% $0.02 0.10% $31 0.30%

TRE 98 1 0.80% -$0.01 0.00% $48 0.30%

WECC 220 0 0.00% $0.00 0.00% $9 0.00%

Total 1,106 1 0.10% $0.00 0.00% $568 0.30%
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 399 of 567

a FRCC (Florida Reliability Coordinating Council), MRO (Midwest Reliability Organization), NPCC (Northeast Power Coordination Council), RFC (Re

SERC (Southeastern Electricity Reliability Council), SPP (Southwest Power Pool), TRE (Texas Reliability Entity), and WECC (Western Electricity C

Exhibit IX-11. Impact of the 

Final Rule on New Capacity 

(GW), at the Year 2030

Capacity Type

Base

line 

Valu

e Final Rule

Value Difference

% 

Cha

nge

Coal 

Stea

m

0 0 0 NA

Combined Cycle

7

5

76 1 0.8%

Combustion 

Turbine

6 6 0

0

.

0

%

Hydro 0 0 0 NA

Nuclear 0 0 0 NA

O/G Steam 0 0 0 NA

Other NonSteama2

5

25 0

0

.

1

%

Other Steamb 9 9 0 0.0%

Total

1

1

4

1

1

5

1 0.5%

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 non-fossil 

waste.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 400 of 567

Impact 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) 

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. 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 401 of 567

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 

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.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 402 of 567

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%

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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 403 of 567

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 Utilizationa1 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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 404 of 567

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%
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 405 of 567

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.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 406 of 567

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 standalone 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-15, EPA 

divided the after-tax, annualized compliance cost by facility-level revenue. Under the 

final rule, EPA found that of 500 Primary Manufacturing Industry facilities, 496 incur 

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

and none incur costs greater than 3 percent. For the nine Other Industries facilities, EPA 

estimated that eight facilities would incur costs less than one percent and one would incur 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 407 of 567

costs between one and three percent of revenue. For Proposal Option 4, all Primary

Manufacturing Industry facilities (500 facilities) and Other Industry facilities (nine

facilities) incur costs less than one percent of revenue. Under Proposal Option 2, 491

Primary Manufacturing Industry facilities incur costs less than one percent and nine

facilities incur costs between one and three percent, while seven Other Industry facilities 

incur costs less than one percent, one facility incurs costs between one and three percent, 

and one facility incurs costs greater than three percent.

Exhibit IX-15. Facility-level cost-to-revenue analysis results

Option

Number of facilities with a cost-to-revenue ratio ofa

<1%

≥1

and <3%

≥3%

Primary manufacturing industries

Proposal Option 4

500 0 0

Final Rule

496 4 0

Proposal Option 2

491 9 0

Other industries

Proposal Option 4

9 0 0

Final Rule

8 1 0

Proposal Option 2

7 1 1

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.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 408 of 567

For the second analysis, EPA assessed how compliance costs would likely affect 

financial performance and condition of the 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 

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.

 

147 This is a sample-weighted estimate of the number of manufacturers, 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 manufacturers is similar in concept to the cash flow 

analysis conducted for electric generators through the IPM analysis.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 409 of 567

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. If 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-16 presents the results from the severe-impact and moderate-impact 

analyses. EPA estimated that no facilities would be at risk of closure as a result of the 

final rule and that 12 facilities could 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 moderate 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 where there is some 

market power and barriers to entry. Thus, these tests present worst case scenario results.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 410 of 567

Exhibit IX-16. Facility impacts and compliance costs for manufacturersd

Proposed Option 4 Final Rule

Proposed Option 

2

c

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 

regulated 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 regulated facility. 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 electric 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 411 of 567

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. 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 

regulated 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-17 presents the results from the entity-level analysis for these two 

cases. EPA estimated that between 120 and 337 entities own 521 regulated facilities. 

Under the final rule, between 90 and 95 percent of all entities are estimated to incur 

compliance costs of less than 1 percent of revenue. This is true also for Proposal Option 

2. Under Proposal Option 4, more entities are expected to incur compliance costs of less 

than 1 percent of revenue (between 94 and 96 percent of all entities).

Exhibit IX-17. Entity-level 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%

# % # % # % # %

 

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.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 412 of 567

Case 1: Lower bound estimate of number of entities that own regulated 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 regulated 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 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

Manufacturing Industries, including Aluminum, Chemicals and Allied Products, Food 

and Kindred Products, Paper and Allied Products, Petroleum Refining, and Steel 

Manufacturing.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 413 of 567

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 

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, 

 

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***

Page 414 of 567

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 

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.

 

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). 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 415 of 567

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 

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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 416 of 567

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 

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 

 

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.

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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 417 of 567

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. 

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.

 

role of market mechanisms in dispatching production of electricity across generating units. See Chapter 2A

of the EA for additional discussion.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 418 of 567

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 waterbody. 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 

impingement and entrainment.155 By reducing impingement mortality and entrainment, 

 

155 See the discussion in Section III on entrainment mortality data and assumptions.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 419 of 567

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, 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 from a series of regional studies representing a range of waterbody 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 

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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 420 of 567

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 section 316(b) industry 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 regulated electric generators, EPA used information from 656 

regulated electric generating facilities that responded to the section 316(b) industry

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 regulated facilities have 

a DIF of at least 2 mgd. EPA estimated regional benefits from the sample of facilities for 

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.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 421 of 567

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 

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, 

 

156 Benefits associated with changes in greenhouse gas emissions were estimated for the nation as whole.

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.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 422 of 567

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.

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 566 107.56 18.06 125.62

Mid-Atlantic 46 24.69 0.07 24.76

Gulf of Mexico 22 10.14 0.05 10.18

North Atlantic 21 5.93 0.00 5.93

South Atlantic 12 5.91 0.05 5.96
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 423 of 567

All Regions 738 181.12 18.46 199.58

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 develop

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.

b Recirculating facilities are facilities with closed-cycle cooling or impoundments that qualify as closed-cycle cooling. Nonrecirculating facilities include facilities with CWIS classified as once-through. 

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 98 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 

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.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 424 of 567

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 

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 

 

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.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 425 of 567

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 

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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 426 of 567

model

159 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.

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 

 

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.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 427 of 567

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 State 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

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 

 

161 Indirect losses account for about 10 percent of commercial and recreational harvest reductions at 

baseline.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 428 of 567

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 

waterbody 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 

from 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. 

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
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 429 of 567

Proposal Option 4

Final Rule – Existing 

Units

Proposal Option 2

Individuals (millions)

IM 419.9 441.3 511.9 568.6

E 399.8 1,693.9 335,447.6 497,316.3

IM&E 819.7 2,135.2 335,959.4 497,884.8

Age-One Equivalents (millions)

IM 612.8 647.5 748.2 824.2

E 1.4 4.5 889.3 1,106.7

IM&E 614.2 652.0 1,637.5 1,931.0

Forgone Fishery Yield (million lbs)

IM 12.6 13.3 15.4 16.9

E 0.0 0.1 35.7 52.9

IM&E 12.6 13.4 51.1 69.8

Production Forgone (million lbs)

IM 129.7 136.5 157.2 174.8

E 0.5 2.4 337.0 451.8

IM&E 130.3 138.9 494.2 626.6

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 standards 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 unit 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. 

Thus, although essential to maintain ecosystem function, the vast majority of biomass 

moving through food webs does not reach higher trophic levels associated with 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 430 of 567

commercial and recreational species and harvest. Instead, the biomass of prey species is 

metabolized and used for predator locomotion, 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 819.7 2,135.2 335,959.4 497,884.8

Forage Species 607.9 1,423.6 224,323.1 325,069.1

Commercial & Recreational Species 211.8 711.5 111,636.3 172,815.8

Commercial & Recreational Harvest 

(millions of fish)

16.1 17.1 44.7 54.0

Lost Individuals with Direct Use Value 1.97% 0.80% 0.01% 0.01%
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 431 of 567

(%)

Age-One Equivalents (millions)

All Species 614.2 652.0 1,637.5 1,931.0

Forage Species 528.2 560.8 1,258.7 1,459.7

Commercial & Recreational Species 85.9 91.2 378.8 471.3

Commercial & Recreational Harvest 

(millions of fish)

16.1 17.1 44.7 54.0

A1E Losses with Direct Use Value (%) 2.63% 2.62% 2.73% 2.80%

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 standards 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 unit 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 establishes entrainment requirements 

for all new stand-alone units at existing facilities. EPA could not directly apply the 

extrapolation methodology used for existing units because facility-specific information 

was not available for new units. 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 unit requirement is summarized in 

Exhibit X-4.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 432 of 567

Exhibit X-4. Annual 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 867.2

Forage Species 566.1

Commercial and Recreational Species 301.1

Commercial and Recreational Harvest (millions of fish) 0.1

Lost Individuals with Direct Use Value (%) 0.01%

Age-One Equivalents (millions)

All Species 2.3

Forage Species 1.7

Commercial and Recreational Species 0.7

Commercial and Recreational Harvest (millions of fish) 0.1

A1E Losses with Direct Use Value (%) 2.87%

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.

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 

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
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 433 of 567

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. 

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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 434 of 567

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 nonuse value. The 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 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 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 

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 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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 435 of 567

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 options 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 

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 EA document for the final existing facilities rule for details on EPA’s 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 436 of 567

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.

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):
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 437 of 567

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 

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 $18 million using a 3 percent discount rate and $14 million using a 7 

percent discount rate. Annual recreational fishing benefits for other options considered 

range from $17 to $43 million using a 3 percent discount rate and $13 million to $30

million using a 7 percent discount rate.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 438 of 567

Exhibit X-5. Annual recreational fishing benefits from eliminating or reducing IM&E at existing units 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 6.1 17.1 12.6

Final Rule – Existing 

Units

6.5 18.2 13.5

Proposal Option 2 20.5 43.0 29.5

Baseline 25.3 78.8 72.0

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 standards 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. 

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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 439 of 567

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.

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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 440 of 567

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 $0.9 million to $3.9 million using a 3 percent discount rate and $0.7 million to $2.7

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 units at 

existing facilities for the final rule and other options considered

Regulatory option a

Increased harvest 3% discount rate 7% discount rate

(million lbs) (million 2011$) (million 2011$)

Proposal Option 4 5.3 0.9 0.7

Final Rule – Existing 

Units

5.7 0.9 0.7

Proposal Option 2 14.0 3.9 2.7

Baseline 17.3 8.0 7.2

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 standards 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.

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 individuals may not use a 

particular waterbody for recreation or fishing, individuals nevertheless may value 

improvements in that waterbody. To quantitatively assess the ecological gains from the 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 441 of 567

final rule and other options considered, EPA took both 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 regulatory options for the North Atlantic and MidAtlantic 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 estimate total values (including both use and 

nonuse values), in general, are benefits transfer or to conduct a stated preference survey. 

There are many studies in the environmental economics literature that quantify benefits 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 442 of 567

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. Nonuse 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 

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.

 

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.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 443 of 567

Estimating 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

(e.g., effects on catchable fish, public access, and observable wildlife). The remaining 

welfare effect—derived purely from effects on forage fish with 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 version 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 

 

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.

165Op cit..
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 444 of 567

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, 

early life stages of recreational and commercial species may be eaten by other 

organisms and therefore have nonuse values.

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 

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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 445 of 567

assuming that the population structure of the current 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 million using a 3 percent discount rate 

and $0.8 million using a 7 percent discount rate. For other options considered, annualized 

nonuse benefits range from $0.3 to $51 million using a 3 percent discount rate and $0.3 to 

$37 million using a 7 percent discount rate.

Exhibit X-7. Annual nonuse benefits from eliminating or reducing IM&E at existing units 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 0.8

Proposal Option 2 4.78 4.18% 51.1 37.3

Baseline 6.23 5.44% 99.1 96.9

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 standards 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. Stated Preference Survey

EPA conducted a stated preference survey to calculate benefits associated with 

minimizing adverse impacts to aquatic ecosystems from cooling water intakes. Refer to 

Sections VI.F.1 and X.D.1 for additional discussion of the stated preference survey. EPA 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 446 of 567

did not rely on the results of its stated preference survey in estimating the benefits of 

today’s rule. 

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.

Consequently, the 316(b) regulation will help preserve threatened and endangered 

species.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 447 of 567

a. Qualitative Assessment of Impingement Mortality and Entrainment Impacts on

T&E Species

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 regulated 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-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.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 448 of 567

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

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. In addition to documented species-level instances of T&E 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 449 of 567

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 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-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-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 State 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 

 

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.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 450 of 567

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 7,930.1 8,245.4 15,659.7 18,841.4

Pallid Sturgeon 65.4 67.6 78.0 89.5

Topeka Shiner 2,910.9 3,009.8 3,471.9 3,984.9

Total 10,906.4 11,322.8 19,209.5 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 

standards 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-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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 451 of 567

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 

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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 452 of 567

benefits for T&E species with quantified impingement mortality and entrainment of $0.4

million using a 3 percent discount rate and $0.3 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 $0.3 to $0.5 million using a 7 percent discount rate.

Exhibit X-10. Annual use benefits from eliminating or reducing IM&E of T&E species at existing units of 

existing facilities for 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 7,995.5 0.4 0.3

Final Rule – Existing 

Units

8,313.0 0.4 0.3

Proposal Option 2 15,737.7 0.7 0.5

Baseline 18,930.9 1.2 1.3

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 standards 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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 453 of 567

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.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 454 of 567

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 using discount rates of 3 percent and 7 percent, 

respectively. EPA is presenting these estimates only to demonstrate the potential range 

 

173 Ibid.

174 U.S. Fish and Wildlife Service (USFWS) (2010c). "North Florida Ecological Services Office: 

Loggerhead Sea Turtle (Caretta )." Available at 

http://www.fws.gov/northflorida/seaturtles/turtle%20factsheets/loggerhead-sea-turtle.htm.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 455 of 567

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 

were $593 million during fiscal year 2011 just on protection of those Federallylisted T&E species that have habitat overlapping cooling water intake structures.

This accounted for 68 percent of the $869 million spent on fish, marine reptiles, 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 456 of 567

crustaceans, corals, clams, aquatic snails and marine mammals listed under the 

Endangered Species Act.175

 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.

 

175 U.S. Fish and Wildlife Service. 2012. Federal and State Endangered and Threatened Species 

Expenditures. Fiscal Year 2011.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 457 of 567

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 benefit to consider when assessing appropriate 

technologies to reduce the effects of cooling water intakes. The installation of 

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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 458 of 567

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 

often extend several miles downstream from outfalls, thermal discharges may impair 

efforts to restore and protect the waterbody. 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 waterbody 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.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 459 of 567

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 decreases or increases, respectively for Proposal Option 4 and Final 

Rule or Proposal Option 2, in energy requirements at regulated facilities under the final 

rule and other options considered. 

EPA’s estimates of changes in CO2 emissions were based on results from the 

electricity market analysis using IPM.

176 For electric generators, EPA estimated the 

change in CO2 resulting from the 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 from the energy penalty and auxiliary energy requirement. For 

compliance technology installation downtime at manufacturers, EPA assumed no change 

in carbon emissions as the short-term replacement of energy by electric power generating 

 

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.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 460 of 567

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 2013 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

Working Group on Social Cost of Carbon. The Agency used the Working+ 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 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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 461 of 567

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 $12 million. Using a 7 percent discount rate, 

annualized benefits under final rule for existing units are $13 million.

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 12.4 13.4

Final Rule – Existing 

Units

12.4 13.4

Proposal Option 2 -1,643.1 -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 

unit 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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 462 of 567

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 unit requirements. Monetized benefits are -$0.2 million 

discounted at 3 percent and -$0.1 million discounted at 7 percent.

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

0.0 0.0 0.1 0.0 -0.3 -0.2

7% discount rate (millions 2011$)

Final Rule 

- New 

Units

0.0 0.0 0.0 0.0 -0.2 -0.1

a

IM&E Effects: Final Rule – New Units - entrainment requirements for all stand-alone facilities 

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 Work 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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 463 of 567

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 

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 Northeast 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 $33 million using a 

3 percent discount rate and $29 million using a 7 percent discount rate. EPA was not able 

to fully monetize the benefits for the final rule. Thus, the estimates represent a 

conservative (i.e., low) estimate of total regulatory benefits of the final rule.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 464 of 567

Exhibit X-13. 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 

Carbonc Total

3% discount rate (millions 2011$)

Final Rule 

– Existing 

Units

18.2 0.9 1.0 0.4 12.4 33.0

Final Rule 

– New 

Units

0.0 0.0 0.1 0.0 -0.3 -0.2

Final Rule 

(Existing 

Units + 

New Units)

18.3 0.9 1.1 0.4 12.1 32.8

7% discount rate (millions 2011$)

Final Rule 

– Existing 

Units

13.5 0.7 0.8 0.3 13.4 28.7

Final Rule 

– New 

Units

0.0 0.0 0.1 0.0 -0.2 -0.1

Final Rule 

(Existing 

Units + 

New Units)

13.5 0.7 0.9 0.3 13.2 28.6

a

IM&E Effects: Final Rule–Existing Units = impingement mortality standards 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. 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 465 of 567

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 

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.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 466 of 567

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 structures

at regulated 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 transfer for a species that represents 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, the results for the proposed 

 

177 U.S. EPA. 2011. Environmental and Economic Benefits Analysis for the Proposed Section 316(b) 

Existing Facilities Rule.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 467 of 567

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 8 of the EA. A copy of the 

EA is available in the docket for this action, and the analysis is briefly summarized here.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 468 of 567

Exhibit XI-1 (drawn from Chapter 8 of the EA) provides the results of the benefitcost analysis.

178 Placeholders for option-specific non-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 IX.E of this preamble and Chapter 9 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 $251.8 $31.0 + BP4

Final Rule $274.9 $32.8 + BFR

Proposal Option 2 $3,643.2 -$1,542.6+ 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. 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 469 of 567

a Social costs and benefits were annualized over 51 years and discounted using 3 percent rate.

b Total social costs include compliance costs to facilities and government administrative costs. See EA Chapter 7.

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 will 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 commence after publication of the draft 

ICR. The information collection requirements are not enforceable until they are approved 

by OMB.

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 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).
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 470 of 567

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 facility

and new unit at an existing facility to prepare and submit information as part of the 

facility’s NPDES permit application. A detailed list of required data items is provided 

below.

EPA estimates an average annual burden of 634,596 hours for the final rule’s

information collection requirements. Of this total, EPA estimates that 1,068 regulated 

facilities will incur an annual average 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 review, 

oversight, and administration of the rule, of 6,930 hours, or an annual average of 147

hours per permitting authority. Slight differences in calculations are due to rounding.

The corresponding estimate of costs other than labor (labor and non-labor 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 $8.5

million. Non-labor costs include activities such as capital costs for sampling equipment, 

remote monitoring devices, laboratory services, photocopying, and the purchase of 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 471 of 567

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. 

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 Section VIII in the preamble.

 Source Water Physical Data (§ 122.21(r)(2))

 Cooling Water Intake Structure Data (§ 122.21(r)(3))

 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))

 Non-Water Quality and Other Environmental Impacts Study (§ 122.21(r)(12))
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 472 of 567

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 are 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 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).

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. 

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.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 473 of 567

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 were designated using employment size thresholds 

specific to each 6-digit NAICS code. 

 For government entities other than Federal or State governments, small 

entities are those with a population of fewer than 50,000.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 474 of 567

 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
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 475 of 567

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 31 and 52 small entities own electric generators that 

are subject to the rule. They represent approximately 25 to 32 percent of entities that own 

electric generators (see Exhibit XI-3).

Exhibit XI-3. Number of entities that own electric generators, by ownership type

Ownership typea

Using facility-level weights Using entity-level weightsb

Total Small % Small Total Small % Small

Cooperative 13 11 84.6% 21 18 85.7%

Federal 1 0 0.0% 1 0 0.0%

Investor-owned 57 6 10.5% 60 7 11.7%

Municipality 19 7 36.8% 38 19 50.0%

Nonutility 26 7 26.9% 30 8 26.7%

Other Political Subdivision 4 0 0.0% 6 0 0.0%

State 3 0 0.0% 3 0 0.0%

All Entity Types 123 31 25.2% 159 52 32.7%
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 476 of 567

a State and Federal 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 

NAICS code NAICS description SBA size standard

111930 Sugarcane Farming $0.75 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
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 477 of 567

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

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
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 478 of 567

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

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 find either 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 479 of 567

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 

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 Industries, representing approximately 16

percent of all entities that own regulated facilities in these industries (see Exhibit XI5).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%
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 480 of 567

Steel 13 1 7.7% 32 2 5.2%

Multiple Industriesa 4 0 0.0% 14 0 0.0%

Primary Manufacturing Industriesb

– Total

110 17 15.5% 327 52 16.0%

a These are small entities that own regulated facilities from multiple industries.

b 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

EPA estimates that between 48 and 104 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 assumed 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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 481 of 567

economic impacts. EPA assumed that entities incurring costs of at least 3 percent of 

revenue have a higher likelihood of 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 no small entities would potentially incur a 

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. The 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 482 of 567

corresponding percentages of small entities are 4 to 13 percent at the 1 percent threshold, 

and zero to 2 percent at the 3 percent threshold. 

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 seven, overall, with three 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 one, overall, 

with no small entities in 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 13 percent, overall, 10 percent for electric 

generators, and 18 percent for manufacturers. At the 3 percent threshold, the maximum

percentage values are 2 percent, overall, zero 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.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 483 of 567

Exhibit XI-6. Estimated cost-to-revenue impact for small entities that own facilities subject to the regulation

Regulated 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 0 to 3 0% to 

10%

0 0%

Manufacturersd 3 to 4 8% to 

18%

0 to 1 0% to 

6%

Electric Generators and Manufacturersd 3 to 7 4% to 

13%

0 to 1 0% to 

2%

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 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 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 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, I certify that the final rule will not have “a 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 Federal agencies, unless otherwise prohibited by law, to assess the effects of 

their regulatory actions on State, local, and Tribal governments and the private sector. 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 484 of 567

Today’s rule contains a Federal mandate that may result in expenditures by 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 11 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 

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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 485 of 567

assumption of no technology installation for facilities with impoundments.

181 The 

existing and new unit provisions of today’s rule are expected to have total annualized pretax (social) costs of $274.9 million. These costs include direct costs incurred by facilities 

and implementation costs incurred by Federal, State, and local governments. The

monetized use and nonuse benefits of the final rule, accounting for the existing and new 

unit provisions, are estimated to be $32.8 million.182 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 8 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 

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.

 

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 generated partial estimates of nonuse benefits for resource 

changes for a species that represents less than one percent of adverse environmental impacts s.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 486 of 567

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 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 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
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 487 of 567

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, from impingement mortality technology at all 

facilities with a DIF of greater than 50 mgd, to 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. EPA 

selected a flexible approach for the final rule from among the options considered; it 

allows consideration of costs and benefits on a site-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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 488 of 567

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 are less than those estimated for facilities 

owned by large government entities, or owned by small or large non-government entities. 

EPA interprets these findings to indicate that the final rule will not 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
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 489 of 567

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-owned electric 

generators, by Size of Governmenta

Entity Type Large Small

Tota

l

Municipality 29 19 48

State Government 6 0 6

Other Political Subdivision 10 1 11

Tribal Government 0 0 0

Total 45 20 65

a Counts of explicitly and implicitly analyzed electric generators; these are not 

weighted estimates. For details, see EA Appendix H.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 490 of 567

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 unit provision of the final rule, EPA estimates that small 

government entities will incur a total annualized cost of $2.6 million, compared to the 

total cost of $8.6 million incurred by large government entities and $8.5 million incurred 

by small private entities. On a per facility basis, EPA estimates that a facility owned by a 

small government entity will on average incur a cost of $0.2 million with a maximum of 

$0.5 million. The Agency estimates that for a facility owned by large government entity, 

the average cost of the existing provision of the final rule will be $0.2 million per facility

with a maximum of $1.3 million, while for a facility owned by a small private entity the 

average cost will be $0.2 million per facility with a maximum of $1.4 million.

183 Again, 

overall, EPA concludes that the compliance requirements of the existing unit 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 11.

 

183 Excluding Federal government entities and regulated facilities they own.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 491 of 567

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 facility

d

Maximum 

facility coste

Final Rule

Government (excluding 

Federal) Small

16 $2.6 $0.2 $0.5

Large

37 $8.6 $0.2 $1.3

Privateb

Small

53 $8.5 $0.2 $1.4

Large

423 $184.3 $0.4 $5.0

All Facilitiesc 544 $220 $0.4 $5.0

aFacility 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.

bFacility counts and cost estimates reported for the private sector include facilities owned by rural electric cooperatives.

cFacility counts and cost estimates reported for All Facilities include facilities owned by the Federal government and costs 

estimated for these facilities.

dEPA calculated average cost per facility using the total number of regulated facilities owned by entities in a given ownership 

category.

eReflects 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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 492 of 567

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) initial

permit issuance activities; (3) annual activities, including monitoring, reporting and 

recordkeeping; and (4) non-annually recurring permit-related activities. Exhibit XI-9

presents total annualized costs for each type of administrative activity. EPA estimates 

that State and local government entities will incur annualized costs of $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

Initial Permit Issuance Activities

$0.2 $0.2 $0.4

Annual Monitoring, Reporting and 

Recordkeeping Activities

$0.2 $0.2 $0.5

Non-Annually Recurring Permit-Related 

Activitiesb

$0.0b $0.0 $0.1

Total

$0.5 $0.4 $0.9

a Costs associated with start-up activities are estimated for both electric generators and manufacturers; these costs are less 

 

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 Federal entities 

in the UMRA analysis.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 493 of 567

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 Federal 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.

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 StateFederal 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 Federal

and State governments.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 494 of 567

EPA estimates an average annual burden of $0.9 million, for State and local 

governments to collectively administer the existing unit 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 554

regulated facilities that are owned by State or local government entities; the Agency

estimates that under the existing unit provision of the final rule these facilities will incur 

an average annual compliance cost of approximately $0.2 million per facility.

186 Because 

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 Tribal implications, as specified in E.O. 13175 (65 FR 

67249, November 9, 2000). It would not have substantial direct effects on Tribal

governments, on the relationship between the Federal government and the Tribes, or the 

distribution of power and responsibilities between the Federal 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 Tribal governments 

are authorized pursuant to CWA section 402(b) to implement the NPDES program. In 

 

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.

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 7 and 11).
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 495 of 567

addition, EPA’s analyses show that Tribal 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 

requirements for cooling water intake structures to protect the 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, the Agency anticipates

that today’s rule may have a significant adverse effect on the supply, distribution, or use 

of energy, thus requiring EPA to include a Statement 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 final rule. Based on that analysis, described in 

Section IX(D)(1)(d) of this preamble (Assessment of the Impacts in the Context of 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 496 of 567

Electricity Markets) and in more detail in Chapter 6 of the EA report, EPA finds that the 

compliance requirements of the final rule may affect the electric power sector in ways 

that would constitute a significant adverse effect under E.O. 13211, and 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 

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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 497 of 567

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.

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 Federal executive policy

on environmental justice. Its main provision directs Federal 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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 498 of 567

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 less 

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 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 

 

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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 499 of 567

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 12).

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 

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.

 

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.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 500 of 567

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.

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, 60 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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 501 of 567

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 BA Chapter 8.

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 major 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].

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
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 502 of 567

Environmental protection, Cooling water intake structure, Reporting and recordkeeping 

requirements, Waste treatment and disposal, Water pollution control.

Dated: 

_____________________

Gina 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.

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. Adding paragraphs (r)(4)(ix) through (r)(4)(xii), replacing paragraph (r)(5), 

and adding paragraphs and (r)(6) through (r)(14).
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 503 of 567

§ 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)(xii)) 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), (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. The owner or operator of an existing facility defined 

at 40 CFR 125.92(k) must submit to the Director for review the information required 

under paragraphs (r)(2) 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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 504 of 567

(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) (9), (10), (11), (12), 

and (13) of this section. 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). 

(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), (5), (8), (14) and applicable provisions of paragraphs (r)(4), (6) and 

(7). Requests for and approvals of alternative requirements sought under 40 CFR 

125.94(e)(2) or 125.98(b)(7)of this chapter must be submitted with the 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), 

(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. Requests for alternative requirements under 40 CFR
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 505 of 567

125.94(e)(2) or 125.98(b)(7) of this chapter must be submitted with 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.

* * * * *

(4) * * *
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 506 of 567

(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.

(xi) For the owner or operator of an existing facility, a list of fragile species, as 

defined at 40 CFR 125.92(m), at the facility. The 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 are from an existing intake.

(xii) For the owner or operator of an existing facility that has obtained 

incidental take exemption or authorization for its cooling water intake structure(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.

(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:
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 507 of 567

(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; the 

proportion of design intake flow for contact cooling, non-contact cooling, and process 

uses; 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; a description of 

reductions in total water withdrawals including cooling water intake flow reductions 

already achieved through minimized process water withdrawals; 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; 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) Description of 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.

(6) Chosen Method(s) of Compliance with Impingement Mortality Standard. 

The owner or operator of the facility must identify the chosen compliance method for the

entire facility; alternatively, the applicant must identify the chosen compliance method 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 508 of 567

for each cooling water intake structure at 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 the applicant chooses to comply with 40 CFR 125.94(c)(5), subject 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 data collection

measuring the reduction in impingement mortality achieved by the modified traveling 

screens as defined at 40 CFR 125.92(s) and demonstrating that the operation has been 

optimized to minimize impingement mortality. A complete description of the modified

traveling screens and associated equipment must be included, including, for example, 

type of mesh, mesh slot size, pressure sprays and fish return mechanisms. A description 

of any biological data collection and data collection approach used in measuring 

impingement mortality must be included:

(A) Collecting data no less frequently than monthly. The Director may establish 

more frequent data collection;

(B) Biological data 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 

collected;
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 509 of 567

(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 the facility entraps fish or shellfish, a count of entrapment, as defined at 

40 CFR 125.92(j), as impingement mortality; and

(G) The percent impingement mortality reflecting optimized operation of the

modified traveling screen and all supporting calculations.

(ii) If the applicant chooses to comply with 40 CFR 125.94(c)(6), the

impingement technology performance optimization study must include biological data

measuring the reduction in impingement mortality achieved by operation of the system of 

technologies, operational measures and best management practices, and demonstrating 

that operation of the 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, credit for intake location, and 

behavioral deterrent systems. The applicant must document how each system element 

contributes to the system’s performance. The applicant must include a minimum of two 

years of biological data measuring the reduction in impingement mortality achieved by 

the system. The applicant must also include a description of any sampling or data 

collection approach used in measuring the rate of impingement, impingement mortality, 

or flow reductions.

(A) Rate of Impingement. If the demonstration relies in part on a credit for 

reductions in the rate of impingement in the system, the applicant must provide an 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 510 of 567

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. The submission of studies more than 10 years old must include

an explanation of why the data are still relevant and representative of conditions at the

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 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 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. In addition, the applicant must include two years of 

biological data collection demonstrating the rate of impingement resulting from the

system. For this demonstration, the applicant must collect data no less frequently than 

monthly. The Director may establish more frequent data collection.

(B) Impingement Mortality. If the demonstration relies in part on a credit for 

reductions in impingement mortality already obtained at the facility, the applicant must 

include two years of biological data collection demonstrating the level of impingement 

mortality the system is capable of achieving. The applicant must submit any relevant 

supporting documentation, including previously collected biological data, performance 

reviews, and previously conducted performance studies not already submitted to the 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 511 of 567

Director. The applicant must provide a description of any sampling or data collection

approach used in measuring impingement mortality. In addition, for this demonstration 

the applicant must:

(1) Collect data no less frequently than monthly. The Director may establish 

more frequent data collection;

(2) Conduct biological data collection that is representative of the impingement 

and the impingement mortality at an intake subject to this provision. In addition, the 

applicant must describe how the location of the cooling water intake structure in the 

waterbody and the water column are accounted for in the points of data collection;

(3) Include a taxonomic identification to the lowest taxon possible of all 

organisms to be collected;

(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 the facility entraps fish or shellfish, a count of the entrapment, as defined 

at 40 CFR 125.92(j), as impingement mortality.

(C) Flow reduction. If the demonstration relies in part on flow reduction to 

reduce impingement, the applicant must include two years of intake flows, measured 

daily, as part of the demonstration, and describe the extent to which flow reductions are 

seasonal or intermittent. The applicant must document how the flow reduction results in 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 512 of 567

reduced impingement. In addition, the applicant must describe how the reduction in 

impingement has reduced impingement mortality.

(D) Total system performance. The applicant must document the percent 

impingement mortality reflecting optimized operation of the total system of technologies, 

operational measures, and best management practices and all supporting calculations. The

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-facility 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 

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. In the case of 

studies more than 10 years old, the applicant must explain why the data are still relevant 

and representative of conditions at the 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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 513 of 567

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 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 process 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 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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 514 of 567

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 data 

collection. The Entrainment Characterization Study must include the following 

components:

(i) Entrainment Data Collection Method. The study should identify and 

document the data collection period and frequency. The study should identify and 

document organisms collected 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 organisms identified by the Director, and any 

species protected under Federal, State, or Tribal law, including threatened or endangered 

species with a habitat range that includes waters in the vicinity of the cooling water 

intake structure. Biological data 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 waterbody and 

the water column are accounted for by the data collection locations;

(ii) Biological Entrainment Characterization. Characterization of all life stages 

of fish, shellfish, and any species protected under Federal, State, or Tribal law (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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 515 of 567

differences, spawning, feeding, and water column migration. This characterization may

include historical data that are representative of the current operation of the facility and of 

biological conditions at the site. Identification of all life stages of fish and shellfish must

include identification of any surrogate species used, and identification of data 

representing both motile and non-motile life-stages of organisms;

(iii) 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 law (including threatened or endangered species). The documentation 

may include historical data that are representative of the current operation of the facility

and of biological conditions at the site. Entrainment data 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 data 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 for that facility

together with all methods and quality assurance/quality control procedures for data 

collection and data analysis. The proposed data 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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 516 of 567

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 as defined at 40 CFR 125.92(c), fine mesh screens with a 

mesh size of 2 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 

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 the 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. 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 517 of 567

(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. The applicant must separately discuss facility level 

compliance costs and social costs, and provide documentation as 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, 

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
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 518 of 567

(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. The 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 benefits of the candidate entrainment reduction technologies and 

operational measures evaluated in paragraph (r)(10) including using the Entrainment 

Characterization Study completed in § 122.21(r)(9) of this section. 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 lost due 

to impingement mortality and entrainment as defined in 40 CFR 125.92, for all life stages 

of each exposed species;

(ii) Description 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 values assigned to changes in the 

stock size or harvest levels of commercial and recreational fish or shellfish species, 

forage fish, and to any other ecosystem or non use benefits;
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 519 of 567

(iv) A discussion of mitigation efforts completed prior to [INSERT effective 

date of final rule] including how long they have been in effect and how effective they

have been;

(v) 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;

(vi) Discussion, with quantification and monetization, where possible, of any

benefits expected 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 penalty;

(ii) Estimates of air pollutant emissions and of the human health and 

environmental impacts associated with such emissions;

(iii) Estimates of changes in noise;
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 520 of 567

(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 

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 the applicant is required to submit studies under §

122.21(r)(10) to (r)(12), the applicant must conduct an external peer review of each

report to be submitted with the permit application. The 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. The 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.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 521 of 567

(14) New Units. The applicant must identify the chosen compliance method for 

the new unit. In addition, the owner or operator that selects the BTA standards for new 

units at 40 CFR 125.94 (e)(2) as its 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 Study at § 122.21(r)(9). In 

addition, if data specific to 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 

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
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 522 of 567

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?

* * * * *

(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).
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 523 of 567

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).

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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 524 of 567

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, 

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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 525 of 567

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.

* * * * *

(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 the 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) * * *
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 526 of 567

(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 

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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 527 of 567

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).

* * * * *

9. 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.

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.

125.99 [Reserved.]
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 528 of 567

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 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 the Clean Water Act (CWA).

(b) Cooling water intake structures not subject to requirements under § 125.94, 

et seq. of this Subpart, 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.

(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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 529 of 567

agency to adopt or enforce any requirement with respect to control or abatement of 

pollution that is more stringent than 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.

(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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 530 of 567

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.

(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:

(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 date 5 years 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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 531 of 567

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 withdrawn from a water of the 

United States to support contact or non-contact cooling uses within a facility, or a system 

designed to include certain impoundments. A closed-cycle recirculating system passes 

cooling water through the condenser and other components of the cooling system and 

reuses the water for cooling multiple times. 

(1) Closed-cycle recirculating system includes a facility with wet, dry, or hybrid

cooling towers, a system of impoundments that are not waters of the United States, or any

combination thereof. A properly operated and maintained closed-cycle recirculating 

system withdraws new source water (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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 532 of 567

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.

(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 

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 facilities, cooling water in a 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 533 of 567

cracking unit, and cooling water directly added to food and agricultural products 

processing.

(e) Cooling water means water used for contact or non-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 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 § 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 United 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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 534 of 567

does not include values associated with emergency and fire suppression capacity or 

redundant pumps (i.e., back-up pumps).

(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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 535 of 567

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.

(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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 536 of 567

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. 

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.

(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.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 537 of 567

(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 

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 a new “stand-alone” unit at an existing facility where 

construction of the new unit begins after [INSERT effective date of the final rule] and 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 538 of 567

that does not otherwise meet the definition of a new facility at § 125.83 or is not 

otherwise already subject to Subpart I of that section. A stand-alone unit is a separate unit 

that is added to a facility for either the same general industrial operation or another 

purpose. 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. 

(v) Offshore velocity cap means a velocity cap located a minimum of 800 feet

from the shoreline. A velocity cap is an open intake designed to change the direction of 

water withdrawal 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 physical and 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 539 of 567

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 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) 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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 540 of 567

subject to the BTA (best technology available) standards for impingement mortality

under paragraph (c), and entrainment under paragraph (d) including any measures to 

protect Federally-listed threatened and endangered species and designated critical habitat 

established under paragraph (g) of this section.

(2) Prior to [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 the 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 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 is subject to the impingement 

mortality standard under paragraph (c), and the entrainment standard under paragraph (d) 

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.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 541 of 567

(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.

(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 practicable, based on a schedule of requirements 

established by the Director. 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 at § 125.94 (e) with respect to the new unit upon commencement of 

the new unit’s operation.

(c) BTA Standards for Impingement Mortality.

The owner or operator of an existing facility must comply with one of the alternatives in 

(c)(1) through (c)(7) below, except as provided in (c)(11) or (c)(12), when approved by 

the Director. In addition, a facility may also be subject to the requirements of (c)(8), 

(c)(9), or (g) of this section if the Director requires such additional measures.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 542 of 567

(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 the actual 

intake flows at a minimum frequency of daily. The 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 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 

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 must be 

achieved under all conditions, including during minimum ambient source water surface 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 543 of 567

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 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 the 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 on 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 

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 is or 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 544 of 567

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 a 12-

month impingement mortality performance standard of all life stages of fish and shellfish 

of no more than 24 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. You must conduct biological 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 545 of 567

monitoring at a minimum frequency of monthly to demonstrate your impingement 

mortality performance. 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.

(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) De minimis rate of impingement. In limited circumstances, rates of 

impingement may be so low at a facility that additional impingement controls may not be 

justified. The Director, based on review of site-specific data submitted under 40 CFR 

122.21(r), may conclude that the documented rate of impingement at the cooling water 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 546 of 567

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 (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.

(12) Low capacity utilization power generating units. If an existing facility has 

a cooling water intake structure used for one or more existing electric generating units,

each with an annual average capacity utilization rate of less than 8 percent averaged over 

a 24-month block contiguous period, the owner or operator may request the Director 

consider 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) through (c)(7) above.

(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. 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 547 of 567

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.

(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)(4) 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 the facility must 

reduce the design intake flow for the new unit, at a minimum, to a level commensurate 

with that which can be attained by the use of a closed-cycle recirculating system for the 

same level of cooling 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 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 under § 125.94(e)(1). This 

demonstration must include a showing that the entrainment reduction is equivalent to 90 

percent or greater of the reduction that could be achieved through compliance with § 

125.94(e)(1). In addition this demonstration must include a showing that the impacts to 

fish and shellfish, including important forage and predator species, within the watershed 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 548 of 567

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 owner or operator of a facility must comply with any alternative 

requirements established by the Director pursuant to § 125.98(b)(7). 

(5) 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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 549 of 567

environmental impact that would not result in a conflict with the Commission’s, the 

Department’s, or the Program’s safety requirement.

(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 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.

(i) More stringent standards. The Director must establish more stringent 

requirements as best technology available for minimizing adverse environmental impact 

if the Director determines that 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, 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 550 of 567

and antidegradation requirements). (j) 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.

(1) The owner or operator of a facility subject to this subpart whose currently

effective permit expires after [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) 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 whose currently

effective permit expires prior to or on [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.
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 551 of 567

(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.

(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) You must submit the information required in 40 CFR 122.21(r) for the new 

unit 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) 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, 

cooling water system, and operating conditions. Any habitat designated as critical or

species listed as threatened or endangered after issuance of the current permit whose 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 552 of 567

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. 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, including a 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 

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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 553 of 567

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 facilities. Monitoring 

requirements for entrainment will be determined by the Director on a site-specific basis, 

as appropriate, to meet requirements under § 125.94(d).

(c) Additional monitoring requirements for existing facilities. The Director may

require additional monitoring for impingement or entrainment including, but not limited 

to, the following:

(1) The Director may require additional monitoring if there are changes in 

operating conditions at the facility or in the source waterbody that warrant a reexamination of the operational conditions identified at 40 CFR 122.21(r).
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 554 of 567

(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(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 the Source Water Baseline Biological 

Characterization data required by 40 CFR 122.21(r)(4). Monitoring methods used must 

be consistent with those used for the Source Water Baseline Biological Characterization 

at 40 CFR 122.21(r)(4). If the Director establishes such monitoring 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 

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

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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 555 of 567

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 a 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 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 waterbody that warrant a reexamination of the operational conditions identified at 40 CFR 122.21(r).
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 556 of 567

(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 

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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 557 of 567

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. Discharge Monitoring Reports (DMRs) (or equivalent 

State reports) and results of all monitoring, demonstrations, and other information 

required by the permit sufficient to determine compliance with the permit conditions and 

requirements established under § 125.94. 

(b) Status reports. Any reports required by the Director under § 125.94.

(c) Annual certification statement and report. An annual certification statement 

signed by the responsible corporate officer as defined in § 122.22 subject to the 

following:

(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. 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 558 of 567

Records 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 reporting 

when necessary to establish permit compliance and may provide for periodic inspection 

of the facility. The Director may require additional reporting including but not limited to 

the records required under § 125.97(d). 

(f) Records of Director’s Determination of BTA for Entrainment. All 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 the 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 any application for a subsequent permit. 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 559 of 567

(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 

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 [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), including any measures to protect 

Federally-listed threatened and endangered species and designated critical habitat 

required by the Director. 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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 560 of 567

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:

(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 monitor as required 

at § 125.94 and § 125.96.

(4) At a minimum, the permit must require the permittee to report and keep the 

records specified at § 125.97.

(5) After [INSERT effective date of the final rule], in the case of any permit 

issued before [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
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 561 of 567

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 Director’s best 

professional judgment on a site-specific basis in accordance with § 125.90(b) and 40 CFR

401.14. 

(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 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;
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 562 of 567

(ii) The alternative requirements must ensure compliance with these regulations, 

other provisions of the Clean Water Act, and State and Tribal 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.

(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 practicable. 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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 563 of 567

require additional study and monitoring if a threatened or endangered species has been 

identified in the vicinity of the intake.

(e) Impingement technology performance optimization study. The owner or 

operator of a facility that chooses to comply with § 125.94(c)(5) or (6) must demonstrate 

in its impingement technology performance optimization study that the operation of its 

impingement reduction technology has been optimized to minimize impingement 

mortality of non-fragile species. The Director may request further data 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 data and performance reviews as part of the study. The 

Director must include in the permit verifiable and enforceable permit conditions that

ensure the modified traveling screens or other systems of technologies will perform as 

demonstrated. The Director may waive all or part of the impingement technology 

performance optimization study at 40 CFR122.21(r)(6) after the first permit cycle

wherein the permittee is deemed in compliance with 125.94(c).

(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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 564 of 567

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 including impingement, 

entrainment, or other adverse effects to Federally-listed threatened or endangered species

or designated critical habitat. Prior to any permit reissuance after [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 

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 Director’s discretion based upon the 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);
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 565 of 567

(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;

(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:

(i) Entrainment impacts on the waterbody;

(ii) Thermal discharge impacts;

(iii) Credit for reductions 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

(vi) Availability of process water, gray water, waste water, reclaimed water, or 

other waters of appropriate quantity and quality for reuse as cooling water.

(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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 566 of 567

is already doing. The Director may reject an otherwise available technology as a BTA 

standard for entrainment if the social costs are not justified by the social benefits.

(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 

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 an opportunity to comment 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 
*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 567 of 567

Service. This includes notice of specific cooling water intake structure requirements at 

124.10(d)(1)(ix),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). 

(j) Nothing 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). 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]