How much does stormwater pollution affect our waters?
States report that stormwater pollution (technically referred to as nonpoint source pollution) is the leading remaining cause of water quality problems. In fact, polluted stormwater runoff is a leading cause of impairment to the nearly 40 percent of surveyed U.S. water bodies which do not meet water quality standards. Common nonpoint source pollutants include sediment, soil, fertilizer and pet waste. The impacts of this type of pollution are subtle and progressive. The changes may be physical– an increase in water temperature and a decrease in clarity. Or they may be chemical- an increase in nutrient (nitrate and phosphorus) levels and a decrease in dissolved oxygen levels. It may take a decade or more for changes to become apparent. Slowly, there may be a decline in fish populations and lakes may fill up with sediment. Unfortunately, the effects of nonpoint source pollutants on specific waters vary and may not always be fully assessed. However, it is clear that nonpoint source polluta
