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.
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.