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  2. Water Quality Criteria

Basic Information on Water Quality Criteria

Using the latest scientific knowledge, the U.S. Environmental Protection Agency develops pollutant-specific criteria for determining whether surface water quality is healthy for people, aquatic life and aquatic-dependent wildlife. These criteria are national recommendations. State and authorized Tribal governments may adopt these criteria into their water quality standards regulations or use them as guidance in developing their own criteria.

Section 304 (a) (1) of the Clean Water Act (PDF) directs the EPA to develop these criteria.

On this page:
  • Aquatic Life Criteria
  • Biological Criteria
  • Human Health Criteria
  • Recreational Criteria

Aquatic Life Criteria

The EPA bases aquatic life criteria on how much of a chemical can be present in surface water before it is likely to harm plant and animal life. The EPA designs aquatic life criteria to protect both freshwater and saltwater organisms from short-term and long-term exposure.

Biological Criteria

Biological criteria are indications of how healthy water bodies based on how many and what kinds of organisms are present.

Human Health Criteria

Pollutants can harm people’s health when they drink water or eat seafood from contaminated surface water. The EPA scientists research how much of a specific chemical can be present in surface water before it is likely to harm human health. Based on this research, the EPA develops human health criteria.

Recreational Criteria

Bacteria and other pathogens (microbes) can make our recreational waters unhealthy for people. The EPA develops recreational criteria to determine when water is safe for recreational activities such as swimming.

Water Quality Criteria

  • Aquatic Life Criteria Table
  • Human Health Criteria Table
  • Human Health Toxics Criteria and Methods
  • Recreational Criteria and Methods
  • Aquatic Life Toxics Criteria and Methods
  • Nutrient Water Quality Criteria
  • Biological Water Quality Criteria
  • Other Aquatic Life Water Quality Resources
Contact Us about Water Quality Criteria
Contact Us to ask a question, provide feedback, or report a problem.
Last updated on September 24, 2024
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