Cooling Water Intakes

  • Cooling Water Intake Screens

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

    Explore rulemaking history

  • Implementation Materials for Regulators

    The EPA provides implementation materials to support permit writers, affected facilities and other interested stakeholders.

    Access regulatory support documents

Cooling water intake structures cause adverse environmental impacts

Intake structures pull large numbers of fish and shellfish or their eggs into a power plant's or factory's cooling system. Thousands of industrial facilities use large volumes of water from lakes, rivers, estuaries or oceans to cool their plants. 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.

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

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Last updated on June 13, 2025