United States

At the federal level, the United States has two sets of water quality guidelines covering environmental protection and human health. The U.S. Environmental Protection Agency (EPA) Aquatic Life Criteria set recommended concentration limits for pollutants and other parameters in ambient water at levels not expected to pose a significant risk to aquatic species. They cover a wide range of substances and conditions, and are established under the Clean Water Act. Individual state and tribal governments may adopt them directly or use them as a starting point for developing their own standards suited to local conditions. The EPA 2012 Recreational Water Quality Criteria are recommended thresholds for protecting human health in coastal and freshwater bodies used for primary contact recreation, including swimming, wading, and water play. Based on epidemiological research linking fecal contamination to illness, they use two bacterial indicators, E. coli and freshwater, and enterococci for both fresh and marine water. As with the aquatic life criteria, states and tribes may adopt these recommendations or develop their own scientifically defensible standards. On the Water Rangers platform, we use both sets of guidelines to help communities interpret monitoring data collected at sites in the United States, whether the question is "is my water healthy?" or "is the water okay for swimming?"