EPA Issues Proposed Rule for Cooling Water Intake Structures

At Existing Facilities

EPA recently released proposed regulations governing cooling water intake structures (CWIS) for existing power plants and manufacturing facilities under the Clean Water Act (CWA). The proposed rule impacts an estimated 1,200 facilities nation-wide, or “over half the water withdrawals in the entire nation.” EPA is accepting comments on the proposal through July 19, 2011.

The proposed rule covers CWIS at existing power-generating, manufacturing, and industrial facilities that: (1) withdraw more that 2 million gallons of water per day; (2) use at least 25% of that water exclusively for cooling purposes; and (3) have a National Pollution Elimination Discharge System (“NPDES”) permit or are required to apply for one. The proposal has three major components: (1) impingement requirements; (2) entrainment requirements; and (3) new units at existing facilities.

Impingement Requirements


The rule imposes a mortality threshold for impingement – i.e., an upper limit on how many aquatic creatures may be killed by being pinned against a facility’s CWIS screens. The proposal designates “traveling fish screens,” combined with a system to return fish captured from the screens, as the best performing technology that will allow facilities to achieve the mortality threshold.

Entrainment Requirements

EPA’s proposal does not designate a specific BTA technology to control entrainment – i.e., death resulting from being sucked into the cooling mechanisms; rather, the rule preserves the status quo by allowing the permitting authority to establish entrainment controls for each facility on a site-specific basis. EPA rejected suggestions to designate “closed cycle cooling technology” as the BTA under § 316(b), even though EPA concluded that closed cycle technology would result in the greatest reduction of entrainment mortality.

The Center supports the proposed rule, however we would have preferred that EPA designate wedgewire screens as BTA technology.  We particularly support that EPA rejected closed cycle cooling technology because such a rule would have led to the closure of many needed facilities. (Marten Law, 6/8/2011)