Municipal Separate Storm Sewer System (MS4)

What Is an MS4?

An MS4, or Municipal Separate Storm Sewer System, is the network of storm drains, ditches, pipes, and other features that collect rainwater and runoff from streets, parking lots, and yards. Unlike the sanitary sewer system, water that enters an MS4 does not go to a treatment plant, it flows directly into local rivers and streams.

Why It Matters

Because stormwater runs off hard surfaces, it can pick up pollutants such as oil, fertilizer, litter, and sediment along the way. When this runoff goes untreated into waterways, it can harm fish, wildlife, and water quality.

The MS4 Program in West Virginia

West Virginia’s MS4 Program is regulated by the West Virginia Department of Environmental Protection (WVDEP) under the federal Clean Water Act. The goal is to reduce pollution in stormwater runoff and protect the state’s streams and rivers.

Cities, towns, counties, universities, and agencies such as the West Virginia Division of Highways (WVDOH) that operate MS4s are required to have a Stormwater Management Program (SWMP). These programs focus on public education, pollution prevention, and proper maintenance of stormwater systems.

How You Can Help

Never dump anything into storm drains.
Properly dispose of yard waste, oil, and chemicals.
Use fertilizers and pesticides sparingly.
Report any signs of illegal dumping or discharges.

Together, we can keep West Virginia’s waters clean and healthy!

Public Outreach

Click on the links below and scroll through the event flyer, social media post, and photo

Municipal Separate Storm Sewer System (MS4)