City Stormwater Program

What is Stormwater?Combination-Storm-Water-Inlet 1


Typical City Storm Drain Stormwater is water from precipitation that flows across the ground and pavement when it rains, snows or ice melts. The water seeps into the ground or drains into what we call storm sewers. These are the drains you see at street corners or at low points on the sides of your streets.
Collectively, the draining water is called stormwater runoff and is a concern to us in commercial and industrial sites, as well as your neighborhood, because of the pollutants it carries. 

Stormwater is not treated once it enters the city storm sewers, therefore all of the untreated stormwater flows into the Yellowstone River.

Yellowstone River Intakes and Outfalls

NOTE: Map file is very large and takes several minutes to load

According to the 1996 National Water Quality Inventory, stormwater runoff is a leading source of water pollution. Stormwater runoff can harm surface waters such as rivers, lakes, and streams which in turn cause or contribute to water quality standards being exceeded.

Stormwater runoff can change natural hydrologic patterns, accelerate stream flows, destroy aquatic habitats, and elevate pollutant concentrations and loadings. Development substantially increases impervious surfaces thereby increasing runoff from city streets, driveways, parking lots, and sidewalks, on which pollutants from human activities settle.

Common pollutants in runoff include pesticides, fertilizers, oils, metals, pathogens, salt, sediment, litter and other debris are transported via stormwater and discharged - untreated - to water resources through storm sewer systems.

Municipal Separate Storm Sewer System (MS4)

The City of Billings is and MS4 co-permittee with Montana Department of Transportation.  The City also has a MS4 partnership with Yellowstone County.  The MS4 General Permit requires permittees to develop, implement, and enforce a Stormwater Management Program (SWMP). The SWMP shall be designed to reduce the discharge of pollutants from the permitted MS4 to the Maximum Extent Practicable (MEP), to protect water quality, and satisfy the appropriate water quality requirements of the Montana Water Quality Act. The SWMP must include Best Management Practices (BMP), control techniques, good standard engineering practices, and other provision necessary to control pollutants. 


The City of Billings Stormwater Program consists of BMPs from the following categories:

  • Construction Site Stormwater Runoff Control
  • Post Construction Stormwater Management for New and Redevelopement
  • Public Education and Outreach
  • Public Participation and Involvement
  • Illicit Discharge Detection and Elimination
  • Pollution Prevention for Municipal Operations
MS4 General Permit


baby geese from ospreynest 002 (2).jpgBest Management Practices (BMPs)
The EPA defines a BMP as a "technique, measure or structural control that is used for a given set of conditions to manage the quantity and improve the quality of stormwater runoff in the most cost-effective manner.” BMPs are used to control stormwater runoff, sediment control, and soil stabilization, as well as management decisions to prevent or reduce nonpoint source pollution.  BMPs are required construction practices for commercial, industrial and residential construction, no matter how big or small the project. Below are commercial and residential handbooks to help determine the types of BMPs necessary for your project. 

These handbooks are also available at the Building Department located on the 4th floor of the Library at 510 West Broadway or at the Public Works Department located at the Depot on 2224 Montana Avenue.

Residential Stormwater Handbook
Commercial Stormwater Handbook

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