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Managing Stormwater: A Leading Cause of Pollution

Managing Stormwater: A Leading Cause of Pollution

Protecting waters from polluted stormwater runoff

Believe it or not: Stormwater is a leading cause of water pollution.

When it rains or snows, the water flows on the ground, runs off solid (impervious) surfaces collecting pollutants (such as oil, pesticides, sediments, bacteria, and other pollutants) that are on those surfaces, and carries them into our waterways. This “runoff” can make our waterways an unhealthy place to live, work, and play. Untreated stormwater runoff entering our streams can result in the contamination of our drinking water supplies; prohibitions on swimming, fishing or boating uses; injury or death to aquatic plants and animals; dangers to public health; and increased flooding.

In many places, this stormwater runoff is conveyed through distinct sewer pipes that bypass the wastewater treatment plants and discharge the polluted runoff directly into our streams and lakes. This system is known as a “municipal separate storm sewer system” or MS4.

In addition to the damage to water quality from MS4s, local governments spend millions of dollars each year trying to rectify the damage to public and private property caused by uncontrolled stormwater runoff. This damage includes repairs to roads, culverts, water, sewer line washouts, flooded homes and yards, the removal of deposited sediment and debris on properties and roads, and repairs of damage to bridges.

Luckily, there are laws out there that protect our waters from polluted stormwater runoff. For example, stormwater from “urbanized (define here what that means) areas”, which are densely settled area that have population of at least 50,000 as designated by the U.S. Census Bureau, is controlled through a National Pollutant Discharge Elimination System (NPDES) permit under the federal Clean Water Act. Under the NPDES program, the Environmental Protection Agency began issuing Municipal Separate Storm Sewer System (MS4) permits almost 30 years ago.

In order to obtain coverage under an MS4 permit, permittees, including municipalities, must implement a Stormwater Management Plan (“SWMP”). These SWMPs must include the development and implementation of “six minimum measures” that prevent or reduce stormwater pollution to the maximum extent possible. The six minimum control measures are:
1. Public Education and Outreach on Stormwater Impacts
2. Public Involvement/Participation
3. Illicit Discharge Detection and Elimination (IDDE)
4. Construction Site Stormwater Runoff Control
5. Post-Construction Stormwater Management (PCSM)
6. Pollution Prevention/Good Housekeeping