vvEPA Environmental Protection
United States	Office of Water EPA-821-F-14-001
Environmental Protection
Agency	www.epa.gov	May 2014
Final Regulations to Establish Requirements for Cooling Water
Intake Structures at Existing Facilities
EPA has finalized standards under the Clean
Water Act to follow through on a settlement
agreement with environmental groups
whereby EPA agreed to issue regulations to
reduce injury and death of fish and other
aquatic life caused by cooling water intake
structures at existing power plants and
factories. These facilities pull in large
volumes of cooling water from lakes, rivers,
estuaries or oceans to cool their machinery.
By setting flexible technology standards,
EPA's common sense regulations will greatly
reduce damage to ecosystems while
accommodating site-specific circumstances
and providing cost- effective options.
This rule covers an estimated 1,065 existing
facilities that each withdraw at least 2 million
gallons per day of cooling water. EPA
estimates that 521 of these facilities are
manufacturers, and the other 544 are power
plants. The technologies required under the
rule have been in use for several decades and
have already been implemented at over 40
percent of facilities subject to this rule.
Section 316(b) of the Clean Water Act
requires that National Pollutant Discharge
Elimination System (NPDES) permits for
facilities with cooling water intake structures
ensure that the location, design, construction,
and capacity of the structures reflect the best
technology available to minimize harmful
impacts on the environment. The withdrawal
of cooling water by facilities removes billions
of aquatic organisms from waters of the
United States each year, including fish, larvae
and eggs, crustaceans, shellfish, sea turtles,
marine mammals and other aquatic life. Most
impacts are to early life stages of fish and
shellfish through impingement (being pinned
against cooling water intake structures) and
entrainment (being drawn into cooling water
systems and affected by heat, chemicals or
physical stress).
Rulemaking History
Under a 1995 consent decree with
environmental organizations, EPA divided the
section 316(b) rulemaking into three phases.
All new facilities except offshore oil and gas
exploration facilities were addressed in Phase
I in December 2001; all new offshore oil and
gas exploration facilities were later addressed
in June 2006 as part of Phase III. This final
rule also removes a portion of the Phase I rule
to comply with court rulings.
Existing large electric-generating facilities
were addressed in Phase II in February 2004.
Existing small electric-generating and all
manufacturing facilities were addressed in
Phase III (June 2006). However, Phase II and
the existing facility portion of Phase III were
remanded to EPA for reconsideration as a
result of legal proceedings. This final rule
combines these remands into one rule, and
provides a holistic approach to protecting
aquatic life impacted by cooling water
Any facility not covered by these national
rules will continue to be subject to section
316(b) requirements set by the EPA, state or
territorial NPDES Permitting Director on a
case-by-case, best professional judgment

Summary of the Rule
There are three main components to the final
First, existing facilities that withdraw at least
25 percent of their water from an adjacent
waterbody exclusively for cooling purposes
and have a design intake flow of greater than
2 million gallons per day (MGD) are required
to reduce fish impingement under the final
regulations. To ensure flexibility, the owner
or operator of the facility will be able to
choose one of seven options for meeting best
technology available requirements for
reducing impingement.
Second, existing facilities that withdraw very
large amounts of water—at least 125 million
gallons per day—are required to conduct
studies to help their permitting authority
determine whether and what site-specific
controls, if any, would be required to reduce
the number of aquatic organisms entrained by
cooling water systems. This decision process
would include public input.
Third, new units that add electrical generation
capacity at an existing facility are required to
add technology that achieves one of two
alternatives under the national BTA standards
for entrainment for new units at existing
facilities. Under the first alternative new unit
entrainment standard, the owner or operator
of a facility must reduce actual intake flow
(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. Under the second
alternative new units entrainment standard,
the owner or operator of a facility must
demonstrate to the Director that it has
installed, and will operate and maintain,
technological or other control measures for
each intake at the new unit that achieves a
prescribed reduction in entrainment mortality
of all stages of fish and shellfish that pass
through a sieve with a maximum opening
dimension of 0.56 inches.
For More Information
Please contact Paul Shriner by email at
shriner.paul@epa.gov or by telephone at
202-566-1076. You can also learn more
about this rule by visiting EPA's website at: