EPA has signed a proposed rule designed to protect fish from being killed by cooling water intake structures at power plants and manufacturing facilities. The proposed rule, issued under section 316(b) of the Clean Water Act, addresses impingement (the trapping of fish against intake screens) and entrapment (the drawing of fish into cooling water systems). The proposed rule was mandated under a settlement agreement with Riverkeeper and other organizations, which agreement requires a final rule by July 27, 2012.

Under the proposed rule, existing facilities that withdraw at least 25 percent of their water exclusively for cooling purposes and have a design intake flow of greater than 2 million gallons per day would be required to reduce fish impingement. The facility owner or operator would be able to choose one of two options: monitoring to show that specified performance standards for impingement mortality of fish and shellfish have been met, or demonstrating to the permitting authority that the intake velocity meets specified design criteria.

For entrapment, the proposal would require that a site-specific determination be made based on local concerns and on the unique circumstances of each facility. Existing facilities that withdraw at least 125 million gallons per day would be required to conduct studies to help their permitting authority determine whether and what site-specific controls would be required to reduce the number of aquatic organisms sucked into cooling water systems. The decision process would require public input. EPA will accept comments on the proposed rule for 90 days after publication in the Federal Register.