Nitrate—the oxidized form of dissolved nitrogen— is the main source of nitrogen for plants. It occurs naturally in soil and dissipates when the soil is extensively farmed. Thus, nitrogen fertilizers are applied to replenish the soil. However, these nitrates can be toxic, especially when they enter the food chain via groundwater and surface water.
Stormwater runoff has emerged as a primary water quality issue. In urban areas, after long dry periods rainwater runoff can contain accumulations of pollutants. Stormwater does not go into the sewer. Instead, pollutants can be flushed into waterways with detrimental effects on the environment and water quality.
Water containing wastes – aka wastewater – from residential, commercial and industrial processes requires treatment to remove pollutants prior to discharge. After treatment, the water is suitable for nonconsumption (nonpotable) and even potable use.
Water quality in California is regulated by several state agencies, including the State Water Resources Control Board (State Water Board) and its nine regional boards, which enforce clean water laws and the Department of Public Health.
Water quality concerns are also often involved in disputes over water rights, particularly in situations involving endangered species or habitat.
