The Water Quality Criteria for Intrastate, Interstate, and Coastal Water were created to embody both state and federal law. State law mandates the protection of public health and welfare and the present use of waters for public water supplies, propagation of fish and aquatic life and wildlife, recreational purposes, and agricultural, industrial, and other legitimate uses. The Federal Clean Water Act requires states to adopt water quality standards. The water quality standards for Mississippi's water are separated into 4 major components: designated uses, narrative "free forms", numeric criteria, and antidegredation provisions. Water quality criteria can include general narrative statements (narrative criteria) and specific numerical concentrations that are calculated to protect aquatic life and human health (numeric criteria). During each triennial review, the criteria are adjusted as needed to reflect changes in law and science. Designated uses are those uses specified in water quality standards for each water body or segment whether or not they are being attained. They take into consideration the use and value of water for public water supplies, protection and propagation of aquatic life, recreation in and on the water (such as swimming and boating), and protection of consumers of fish and shellfish. Mississippi waters are classified into the following uses: Public Water Supply, Shellfish Harvesting, Recreation, Fish and Wildlife, Ephemeral.