The Clean Water Act establishes three major steps for water quality protection.
States designate one or more beneficial uses for each water body or stream segment.
For waters designated as drinking water sources, human health criteria are used. Wildlife and habitat criteria standards are also applied in some cases. These are generally more stringent than those for drinking water, which are applied at the faucet after municipal treatment. Criteria are critical technical information about the effects of a specific pollutant on human health or aquatic life and specifies the maximum allowable concentrations which are protective of aquatic life or human health. Criteria are developed by EPA and are published as guides to states for the development of water quality standards.