On May 19, 2014, U.S. EPA promulgated final regulations that established requirements for cooling water intakes at existing power plants and industrial facilities. After almost 20 years of attempting to adopt rules under Section 316(b) of the Clean Water Act, U.S. EPA's new regulations, which apply to existing facilities that withdraw more than 2 million gallons of water per day from waters of the United States and use at least 25% of that water for cooling purposes, require affected facilities to implement one of seven options intended to minimize potential adverse environmental impacts (primarily impingement and entrainment). The facilities are not allowed, on their own initiative, to select one of these seven options. Instead, the permitting authority (U.S. EPA or the state) will evaluate specific information provided by the regulated facility and then select the appropriate technology from the seven options. It is important to note that the regulators must consider whether the benefits justify the costs and it might be the case that no controls are necessary if the costs are not justified by the benefits.

The rule (which is 559 pages and accompanied by a 339-page biological opinion from U.S. Fish and Wildlife Service), is the culmination of litigation by several environmental groups and six states that challenged final regulations setting national performance standards in 2004. After several years of litigation, U.S. EPA entered into a settlement agreement pursuant to which it agreed to promulgate final regulations in 2014. Early indications are that industry is generally satisfied with the final rule; environmental groups, however, including the Natural Resources Defense Council have already announced their intention to file a court challenge to the rule. One can only wonder whether it will be another decade before these regulations are truly finalized.