Water quality standards determine water quality requirements. The Clean Water Act, federal regulations and State Water Control Law protect the water quality of state waters and provide for the restoration of other waters to support reasonable public uses and the growth of aquatic life. The State Water Control Board follows the laws to maintain water quality standard laws in Virginia.

Water quality standards contain numeric limits for specific physical, chemical, biological or radiological characteristics of water. As not all requirements for water quality protection can be numerically defined, standards also include general and specific descriptions. These statements and numeric limits describe the water quality necessary to meet and maintain uses, such as swimming and other water-based recreation, public water supply, and the propagation and growth of aquatic life.

Virginia manages water quality of its streams, lakes, reservoirs and tidal waters though a continuing planning process managed by DEQ in cooperation with several state agencies, local governments, private organizations, industry, citizens and the federal government. Water quality standards are an integral part of this process.