URBAN STORMWATER RUNOFF

After rain, streets look cleaner – and that’s a problem, because stormwater  rushing over paved surfaces picks up  everything from oil to dirt and pesticides and then flows – either directly or via storm drains – into streams, rivers and lakes and ultimately to the ocean. This phenomenon is called nonpoint source pollution. The United States Environmental Protection Agency (EPA) considers nonpoint source pollution the third most significant cause of water quality impairment in the nation’s water bodies, surpassed only by agricultural runoff and industrial discharges.

The porous and varied terrain of natural landscape like forests, wetlands and grasslands trap rainwater and snowmelt and allow it to slowly filter into the ground. Runoff tends to reach receiving waters, such as lakes and streams, gradually and after some polluting material has been filtered out. In contrast, nonporous landscapes like roads, parking lots and buildings do not let runoff percolate into the ground. Water remains above the surface, accumulates and then runs off in large amounts.  

Cities install storm drain systems that quickly channel runoff from roads and other impervious surfaces. The runoff gathers speed once it enters the storm drain system and when it leaves the drain and empties into a stream, large volumes of quickly flowing runoff erode stream banks, damage streamside vegetation and widen channels. Negative results include lower water depths during non-storm periods, higher than normal water levels during wet weather periods, increased sediment loads, and higher water temperature levels. Native fish and other aquatic life cannot survive in urban streams severely impacted by urban runoff.

Urbanization also increases the variety and amount of pollutants transported to receiving waters. Sediment from new construction; oil, grease and toxic chemicals from motor vehicles; nutrients and pesticides from turf management and gardening; virus and bacteria from failing sewer systems; road salts and heavy metals are examples of pollutants generated in urban areas. Everyday activities such as driving and maintaining vehicles, maintaining lawns and parks, disposing of waste and even walking pets cover paved surfaces with various harmful materials that enter storm drains as untreated runoff.  Increased pollutant loads can harm fish and wildlife populations, kill native vegetation, foul drinking water supplies, and make recreational areas unsafe.

Together, these pollutants and the increased velocity and volume of runoff cause dramatic changes in hydrology and water quality, resulting in such problems as increased flooding, stream channel degradation, habitat loss, changes in water temperature, contamination of water resources, and increased erosion and sedimentation – all harmful to ecosystem functions, biological diversity, public health, recreation, economic activity and general community well-being.

Things You Can Do to Help.

·        Don’t wash down your driveway, sidewalk or entryway; use a broom and dispose of debris in a trash can.

·        Pick up pet waste immediately and dispose of it in a toilet or a trash can.

·        Carefully follow directions on pesticides, herbicides and fertilizer. Do not over use, and avoid washing these chemicals into catch basins and streets.

·        Maintain your car to avoid leaks. Put a mat under your car or use cat litter to absorb spills. 

·        Never pour cleaning materials or paint onto the ground or in the street.

·        Move your car off the street on street sweeping days.

·        Don’t put grease down your sink drains; pour it into a container and put it into a trash can. 

Every person must do their part to prevent urban run-off. To learn how you can help, do to the City’s website (www.lagunawooscity.org) and read the articles on water quality. Or, stop by city hall and pick up helpful information.

Remember, the ocean starts at your front door. Keep it Clean!