Cooling Water Intakes

  • Cooling water intake and fish screen

  • Examples of cooling towers

Thousands of industrial facilities use large volumes of water from lakes, rivers, estuaries or oceans to cool their plants.

Cooling water intake structures cause adverse environmental impact by pulling large numbers of fish and shellfish or their eggs into a power plant's or factory's cooling system.
  • Organisms may be killed or injured by heat, physical stress, or by chemicals used to clean the cooling system.
  • Larger organisms may be killed or injured when they are trapped against screens at the front of an intake structure.

Section 316(b) of the Clean Water Act requires the EPA to issue regulations on the design and operation of intake structures, in order to minimize adverse impacts. 

Regulated Facilities

Regulated facilities have NPDES permits and are designed to withdraw at least 2 million gallons per day from waters of the U.S.
 
Many industrial sectors are affected. The sectors with the largest number of regulated facilities are:
  • Electric generating plants
  • Pulp and paper mills
  • Chemical manufacturing plants
  • Iron and steel manufacturing
  • Petroleum refineries
  • Food processing
  • Aluminum manufacturing
For precise definitions of coverage, see the regulations at 40 CFR 125.81, 125.91 and 125.131.

Regulations

The cooling water intake requirements are included in the NPDES permit regulations, 40 CFR Parts 122 & 125 (Subparts I, J, & N).

2014 - Existing Electric Generating Plants and Factories
Rulemaking History
Implementation Support
Contact Us to ask a question, provide feedback, or report a problem.
Last updated on March 19, 2025