Urban stormwater is rain or snowmelt that flows over both impervious surfaces like driveways, sidewalks, and streets; and pervious surfaces like lawns and gardens. It picks up litter, toxic chemicals, dirt, and other pollutants as it runs off into a storm drain that discharges to an underground storm sewer system. Anything entering a storm drain is generally piped directly to the closest body of water, typically a creek, stream pond, lake or river, with no treatment in-between.
Quantity of Stormwater Runoff
Impervious surfaces generate runoff every time it rains. A typical city block generates nine times more runoff than a woodland area of the same size! The quantity of runoff from these areas quickly overwhelms natural channels and streams, often causing channel erosion, localized flooding and property damage.
What you can do to reduce runoff quantity....
- Collect runoff from your roof in a rain barrel or cistern.
- Direct your downspout towards a vegetated, pervious surface rather than your driveway or patio.
- Capture more runoff on your lot through native landscaping, rain gardens or soil quality restoration.
Quality of Stormwater Runoff
Surface pollutants such as automobile oil, grease, brake pad dust, sediment from construction sites, bacteria from animal waste, excess lawn care fertilizers and pesticides, as well as atmospheric deposition of phosphorus, nitrogen and other airborne pollutants are washed away in water. The initial flush of runoff can carry high concentrations of these pollutants to nearby drinking water supplies, waterways, beaches and properties. Pollution washed from the land surface by rainfall is called nonpoint source pollution.
What you can do to protect stormwater quality...
- The best way to protect stormwater runoff quality is to avoid polluting in the first place. Conserve and recycle resources such as newspapers, plastic containers, glass jars, and metal cans.
- Don’t dump hazardous substances such as used oil, household chemicals, yard fertilizer, or other wastes onto pavement or into storm drains.
- Practice picking up litter and disposing of leaves and yard waste properly.
- Prevent excess runoff of pesticides, fertilizers, and herbicides by using them properly and efficiently.
- Participate in local garbage and debris pickup days, and recycle household hazardous waste materials to prevent storm drain contamination.
- Encourage active citizen participation in stormwater protection and public group education on stormwater quality.
Questions? Call Public Works at (515) 223-6231.