The State Water Control Law mandates the protection of existing high-quality state waters and provides for the restoration of all other state waters so they will permit reasonable public uses and will support the growth of aquatic life. The adoption of water quality standards under Section 62.1-44.15(3a) of the law is one of the State Water Control Board's methods of accomplishing the law's purpose. This section also requires the water quality standards to be updated at least every three years.
The Clean Water Act 303(c) or 33 USC Chapter 26 Section 1313 also mandates the adoption of water quality standards and a review of the standards every three years.
The Federal Water Quality Standards Regulation 40 CFR 131 specifies minimum requirements for water quality standards.