Definitions for "Water quality standard"
The combination of a designated use and the maximum concentration of a pollutant which will protect that use for any given body of water. For example, in a trout stream, the concentration of iron should not exceed 1 mg/l.
A legally established state regulation consisting of three parts: (1) designated uses, (2) criteria, and (3) antidegradation policy.
Under the Clean Water Act, the states establish "water quality standards" based on guidelines issued by EPA. The state water quality standards set limits on the concentration of pollutants permitted in different categories of water depending on their designated use. In other words, states designate water bodies for particular uses – such as public drinking water, recreational, or agricultural use – and assign corresponding pollution limits to each category. State water quality standards must be approved by EPA.