What is stormwater runoff?
Stormwater runoff occurs when precipitation from rain or snowmelt flows over the ground. Impervious surfaces like driveways, sidewalks, and streets prevent stormwater from naturally soaking into the ground.
How do urbanized areas affect water quality?
The porous and varied terrain of natural landscapes like forests, wetlands, and grasslands traps rainwater and snowmelt and allows them to filter slowly into the ground.
Why is stormwater runoff a problem?
Stormwater can pick up debris, chemicals, dirt, and other pollutants and flow into a storm sewer system or directly to a lake, stream, river, wetland, or coastal water. Anything that enters a storm sewer system is discharged untreated into the waterbodies we use for swimming, fishing, and providing drinking water.
- Clouds the water and makes it difficult or impossible for aquatic plants to grow.
- Can destroy aquatic habitats.
- Results in increased flooding due to reduced stream capacity.
- Excess nutrients can cause algae blooms:
- When algae die, they sink to the bottom and decompose in a process that removes oxygen from the water.
- Fish and other aquatic organisms can’t exist in water with low dissolved oxygen levels.
- Bacteria and other pathogens can wash into swimming areas and create health hazards, often making beach closures necessary.
- Debris washed into waterbodies can harm aquatic life like ducks, fish, turtles, and birds.
- Household hazardous wastes like insecticides, pesticides, paint, solvents, used motor oil, and other auto fluids can poison aquatic life. Land animals and people can become sick or die from eating diseased fish and shellfish or ingesting polluted water.
- Polluted stormwater often affects drinking water sources. This, in turn, can affect human health and increase drinking water treatment costs.
- Increased impervious area leads to a loss of infiltration which may cause profound groundwater changes. Although urbanization leads to increases in flooding during storm events, in many instances it results in lower stream flows during dry weather.
- Warm water runoff from streets, rooftops, and parking lots increases the temperature of streams which is harmful to aquatic life, including trout in NC.
What can I do to help?
For more information on local water quality programs and volunteer opportunities you can visit the following websites: