The EPA’s 2014 cooling water rule for existing power plants (40 C.F.R. pts. 122, 125) has survived challenges from both environmental and industry groups. The Second Circuit Court of Appeals upheld the contentious rule which allows for, among other things, case-by-case determinations of best technology available (BTA) required for minimizing adverse environmental impacts from cooling water intake structures (CWISs), finding that the rule was based on reasonable interpretations of applicable statutes and sufficiently supported by the factual record.

By way of background, once-through CWISs use tremendous volumes of surface water to dissipate heat from power plants. Fish trapped against the intake screens (impingement) or passing through the cooling water system (entrainment) can be injured or killed. Closed-cycle cooling systems use much less surface water and therefore impact fewer fish. Most existing power plants were built with once-through CWISs.

The rule allows for the Director of a state’s Clean Water Act permitting program to determine the BTA to limit entrainment on a site-specific basis. Environmental challengers argued that the rule should have identified closed-cycle cooling as the BTA. The Second Circuit disagreed, stating that the rule explains that closed-cycle cooling is infeasible at some existing facilities because of space constraints, emissions impacts arising from the additional energy requirements of closed cycle cooling, and the absence of net benefits associated with power plants nearing the end of their useful lives. Environmental challengers also argued that the cost of closed-cycle cooling should not have been considered in evaluating the best technology available. Again the Second Circuit disagreed, stating that EPA did not improperly consider costs, and that agencies are generally required to consider the costs and benefits of a regulation.

Regarding impingement, the rule identifies “modified traveling screens with a fish-friendly return” as the best technology available, rather than the closed-cycle cooling preferred by environmental challengers. Modified traveling screens are projected to achieve a 76% survival rate for impinged “non-fragile species.” Environmental challengers argued that the exclusion of fragile species was an arbitrary distinction. However, the Second Circuit accepted EPA’s “adequately supported” explanation that inclusion of fragile species masks the effectiveness of impingement technology, and that EPA’s data shows that mortality of fragile species depends on natural conditions rather than technology performance.

The Court also rejected a flurry of arguments relating to EPA’s site-specific process for evaluating impacts on endangered species, as well as the administrative law arguments advanced by industry challengers. Barring Supreme Court review, this decision marks the end of over 30 years of litigation regarding CWIS rules. Given the site-specific nature of the final rule, arguments previously used to challenge the sufficiency of the CWIS rules will likely now be used to challenge permits granted to existing power plants.