Stormwater 101

What is stormwater?

Impervious surfaces, such as rooftops, driveways, sidewalks, and roads prevent rainwater from soaking into the ground. When it rains on these hard surfaces rainwater becomes stormwater runoff which can carry harmful pollutants which have been left on land to downstream water bodies. Stormwater runoff may flow overland or be transported by a ditch or storm drain and discharged into a nearby waterway. The pollution we leave on the ground, such as pet waste, excess fertilizers, litter, gasoline, and oil, can end up in downstream water bodies. As a result, stormwater runoff is considered the greatest threat to water quality in the United States. In South Carolina more than 1,150 of our waterways have been classified as "impaired," which means they are too polluted or degraded to meet accepted water quality standards. As watershed stewards, we can all do our part to help protect clean water for current and future generations!

What causes stormwater pollution?

Stormwater becomes polluted when runoff flows over pollutants that have been left on the ground. Common sources of pollution include bacteria from pet waste and ill-maintained septic tank systems, sediment from construction sites and areas of bare soil, litter, pesticides, nutrients from excess fertilizers, improperly stored or disposed of household chemicals, oil from leaky automobiles, detergents from car washing, paint residues, and more. Properly disposing of waste and using best management practices (keep reading!) are excellent ways to prevent stormwater pollution.

What are stormwater BMPs?

Stormwater Best Management Practices (BMPs) include behaviors and structural installations that help to manage water quality and water quantity, reducing the amount of polluted stormwater runoff that enters our community water bodies. Learn more about BMPs in this section.

Stormwater in action