Large Municipal Separate Storm Sewer Systems

As urbanization progresses and municipalities expand, there is a need to manage and mitigate the effects of urban runoff. When stormwater drains off of roads, sidewalks, driveways, parking lots, etc. it can carry sediment, debris, and other pollutants that can harm aquatic life, lakes, streams, wetlands, and reduce water quality. Municipal separate storm sewer systems (MS4) are a system of conveyances that are designed and used to collect or convey stormwater and then discharge the stormwater untreated into local water bodies. Per 40 Code of Federal Regulations (CFR) §122.26, discharges from an MS4 serving a population of 100,000 or more and road systems owned by states that discharge to water of the United States require a stormwater permit. Large MS4s are located in an urban area with 250,000 people or more. There are 3 Large MS4s in Nevada, and they are: 

• Las Vegas Valley - Permit NV0021911 that authorizes stormwater discharges into receiving waters of the United States within the Cities of Henderson, Las Vegas and North Las Vegas, and Clark County that are located within the Las Vegas Valley.
  • Las Vegas Valley MS4 Permit
  • Las Vegas Valley MS4 Permit Fact Sheet
• Truckee Meadows - Permit NVS000001 that authorizes stormwater discharges into receiving water of the United States within the Cities of Reno and Sparks, and Washoe County that are located within the Truckee Meadows.
  • Truckee Meadows MS4 Permit
  • Truckee Meadows MS4 Permit Fact Sheet
• Nevada Department of Transportation (NDOT) - Permit NV0023329 that covers state and interstate highways and their right-of-ways within the jurisdictional boundary of NDOT served by, or otherwise contributing to discharges into receiving waters of the United States from MS4s owned or operated by NDOT.
  • NDOT MS4 Permit
  • NDOT MS4 Permit Fact Sheet

External Links

• EPA Stormwater Program
• Truckee Meadows Regional Stormwater Quality Management Program
• Las Vegas Valley Stormwater Quality Management Committee
• NDOT's Stormwater Management Program