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Yellowstone County, Montana
Public Works
Storm Water Management Program Contact Department
Frequently Asked Questions about Storm Water
What is storm water and storm water pollution?

As precipitation falls to the ground in the form of rain or snow, impervious surfaces such as driveways, roads, and parking lots prevent this precipitation from infiltrating into the ground, resulting in storm water runoff. This runoff eventually reaches local surface waters such as streams, creeks, rivers, and lakes. Impervious surfaces have various types of pollutants that can be carried to local waterways and make them unsafe for humans and wildlife.

Photo Courtesy of HDR
Photo Courtesy of HDR

What is a MS4 and a MS4 Program?

Yellowstone County owns and operates a Municipal Separate Storm Sewer System (MS4). A MS4 is a conveyance or system of conveyances that discharge storm water runoff to surface waters. To help manage and reduce storm water pollution, the Montana Department of Environmental Quality requires Yellowstone County to implement a MS4 Storm Water Management Program in accordance with the requirements described in the Montana MS4 General Permit. The Storm Water Management Program consists of six topics that need to be addressed:

  1. Public Education
  2. Public Outreach & Participation
  3. Illicit Discharge Detection & Elimination
  4. Construction Site Storm Water Management
  5. Post-Construction Storm Water Management
  6. Good Housekeeping/Pollution Prevention

Photo Courtesy of HDR
Swale Drywell
Photo Courtesy of HDR

A copy of the Montana MS4 General Permit is located below as well as a link to the Montana DEQ Storm Water Website.
Construction activities within Yellowstone County are required to comply with all applicable DEQ stormwater permitting requirements. The County is currently in the process of defining the specific additional construction stormwater permitting requirements required with the County's MS4 permit boundary.

Learn about Yellowstone County's Storm Water Management Program

Yellowstone County has developed a comprehensive document to address the six topics listed above. A link to the most recent version of the County's Storm Water Management Program, annual reports, and the County's Storm Sewer Inventory Map are provided below. The public is encouraged to review this information and to provide input by contacting the Public Works Department at
(406) 256-2735.

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Useful Links

The County has developed outreach materials to help spread awareness about storm water and storm water pollution prevention. Links to these materials are provided below and include recommendations for how you can help reduce storm water pollution.

Report Illegal Dumping

Illegal dumping takes place when any waste material is accidentally or purposely dumped into a surface water, gutter, or storm drain. Illegal dumping causes pollution and damages our local water ways. Examples of illegal dumping include:
  • Dumping household chemicals
  • Dumping vehicle fluids
  • Trash & debris
  • Sanitary waste water (sewage)
Photo Courtesy of HDR

To report illegal dumping of liquids or other materials into the storm drainage system in Yellowstone County, please contact the Public Works Department at (406) 256-2735.

Upcoming Events
  • Montana Fair Storm Water Booth (August 13-21, 2021- Billings)
  • SWPPP Administrator Training (These trainings are held throughout the year at a variety of locations and dates. Training schedules can be found externally at Altitude Training Associates and StormwaterOne websites)
  • Montana Storm Water Conference (May 3-5, 2021- Missoula)
  • Montana Contractors Association Annual Convention (January 27-29, 2021- Helena)
  • Billings Homebuilder's Association Meetings (These meetings are postponed until later notice due to COVID-19.)

General Comments or Complaints

Yellowstone County and the City of Billings work together to reduce storm water pollution while managing separate Storm Water Management Programs. If you would like to be involved with either of these programs or if you have any comments or complaints, please use the following procedures for contacting your local representative:
  • For residents not within City Limits, please contact the Yellowstone County Public Works Department at (406)-256-2735.
  • For residents within City Limits, visit the City of Billings storm water website for additional information