United States Environmental Protection       Office of Water          EPA-821-F-04-003
Agency                           4303T                February 2004

Final Regulations for Cooling Water Intake Structures
at Large Power Plants (Phase II)
On February 16, 2004, EPA established location, design, construction and capacity standards for
cooling water intake structures at large power plants.  The Clean Water Act calls for EPA to establish
the best technology available to protect fish, shellfish and other forms of aquatic life. The final rule
sets standards but provides flexibility by offering several alternatives for power plants to comply.


Section 316(b) of the Clean Water Act (CWA) requires EPA to ensure that the location, design,
construction, and capacity of cooling water intake structures reflect the best technology available to
protect aquatic organisms from being killed or injured by impingement (being pinned against screens
or other parts of a cooling water intake structure) or entrainment (being drawn into cooling water
systems and subjected to thermal, physical or chemical stresses).

EPA divided this rulemaking into three phases: Phase I for new facilities was completed in
December 2001.  This rule, Phase II, is for existing electric generating plants that use large amounts
of cooling water. Phase II addresses large existing power plants that are designed to withdraw 50
million gallons per day or more and that use at least 25 percent of their withdrawn water for cooling
purposes only. Scheduled for proposal in November 2004, Phase III will apply to electric generating
plants using smaller amounts of cooling water  and for other industrial sectors.

The withdrawal of cooling water removes billions of aquatic organisms from waters of the U.S. each
year, including fish, fish larvae and eggs, crustaceans, shellfish, sea turtles, marine mammals, and
many other forms of aquatic life. Most impacts are to early life stages offish and shellfish.

When the quantity of water withdrawn is large relative to the flow of the source waterbody, more
organisms will be affected. Intakes in coastal waters, estuaries, and tidal rivers tend to have greater
ecological impacts than those in freshwater lakes and offshore ocean intakes,  since these areas are
usually more biologically productive and have more aquatic organisms in early life stages.

Summary of the Final Rule

The final rule requires protection against these losses. For example, impingement requirements call
for the number of organisms pinned against parts of the intake structure to be  reduced by 80 to 95
percent from uncontrolled levels. Entrainment requirements call for the number of aquatic organisms
drawn into the cooling system to be reduced by 60 to  90 percent from uncontrolled levels. Large
power plants have flexibility to comply and to  ensure energy reliability. The rule provides several
compliance alternatives, such as using existing technologies, selecting additional fish protection
technologies (such as screens with fish return systems), and using restoration  measures.

Environmental Benefits and Costs

EPA conducted rigorous scientific and economic analyses to develop this rule. The Agency worked
with states, industry groups, and environmental organizations to determine, on a national basis, how
best to protect the aquatic life that are critical to the environment and to commercial and recreational
activities. EPA considered the costs and financial impacts to industry and its ability to produce
energy in developing flexible compliance alternatives. The rule will not interfere with the supply,
distribution, or use of energy produced by these power plants.

This rule protects more than 200 million pounds of aquatic organisms annually from death or injury
by cooling water intake structures. The  impingement and entrainment reduction benefits range from
$73 million to $83  million per year. These benefits are primarily from improvements to commercial
and recreational fishing. There are likely to be  other benefits, for example, more robust and
productive aquatic ecosystems, although these  are harder to quantify.  EPA estimates that this rule
affects about 550 facilities and costs about $400 million per year.

How to Get Additional Information

For more information, please call Debbi Hart at 202-566-6379 or send an email to
hart.debbi@epa.gov. You can also learn more about this final rule and other actions addressing
cooling water intake structures by visiting EPA's Internet web site at
http ://www. epa. gov/water science/316b.