Urban Stormwater Program Overview
MDT's MS4 Stormwater Management Program

The Federal Water Pollution Control Act (the Clean Water Act) provides the basis for regulating the discharge of pollutants to waters of the United States through implementation of the National Pollutant Discharge Elimination System (NPDES), which is administered by the Environmental Protection Agency (EPA).

In 1974, the EPA delegated Montana authority to implement many CWA programs within the state. Through agencies and laws, Montana executes federal water quality guidelines, updating its delegated programs to reflect changes at the federal level [2002, EQC ]. The agency in Montana that is responsible for implementing these programs is the Department of Environmental Quality (DEQ), which they do through the Montana Pollutant Discharge Elimination System (MPDES).

At first the NPDES and MPDES programs primarily focused on regulating pollution discharged from point sources. However in 1987 Congress amended the CWA to include requirements for regulating stormwater discharges from municipal separate storm sewer systems (MS4's). This would be implemented in two phases: Phase I, implemented in 1990, regulated MS4's in large or medium cities generally with populations greater than 100,000. Phase II, implemented in 1990 at the federal level, regulates MS4's in "small" cities with populations of less than 100,000.

EPA Phase I and II requirements have been incorporated into the Administrative Rules of Montana (ARM), Title 17, Chapter 30, Subchapters 11, 12, and 13 . These rules became effective on February 14, 2003, and require small MS4's to obtain coverage under a stormwater discharge general permit.

In January 2005, the Montana Department of Environmental Quality (DEQ) issued a new general permit known as the Small Municipal Separate Storm Sewer System (MS4) permit. The permit is required for urban areas within the state of Montana that have storm sewer systems that serve a population of at least 10,000 people. Areas included in the permit are Billings, Missoula, Great Falls, Butte, Helena, Kalispell, and Bozeman. Cities, counties, universities, military bases, and the Montana Department of Transportation (MDT) are some of the entities required to obtain the permit for these areas. Under the permit, they are required to develop, implement, and enforce a Storm Water Management Program (SWMP) designed to reduce the discharge of pollutants from the Small MS4, to protect water quality, and to satisfy the appropriate water quality requirements of the Montana Water Quality Act.

This SWMP must include the development and implementation of Best Management Practices (BMPs) and measurable goals for the following six "minimum control measures":

  1. Public education and outreach on stormwater impacts;
  2. Public involvement/participation;
  3. Illicit discharge detection and elimination;
  4. Construction site stormwater runoff control;
  5. Post-construction stormwater management in new development and redevelopment; and,
  6. Pollution prevention and good housekeeping for municipal operations.

According to the permit, a small MS4 can work with the owners or operators of adjacent small MS4s in developing and implementing a shared SWMP in which each permittee is responsible for activities that are within their individual legal authorities and jurisdictional areas. MDT worked with the other governmental entities and reached agreements to share responsibilities and submit joint applications as co-permittees in six of the seven designated areas.

The application packages, including the SWMP proposals, were submitted to DEQ in 2003 in order to comply with the federal stormwater regulations. However, general permit coverage was not issued until mid-2006. MDT has reviewed their portion of the 7 SWMPs and developed an updated plan to ensure compliance with the now final General Permit. The intent of the new MDT program document is also to combine the elements of the previously separate MDT programs for the 7 designated urban areas into one consistent MDT program for each of the designated areas. This MDT SWMP is not intended to replace the shared SWMPs that are established with MDT co-permittees.

Elements of this MDT SWMP would modify/supplement the MDT portion of the shared SWMP in areas where MDT is a co-permittee and replace the SWMP in Helena. Several goals are intended:

  • Create consistency across the department which will promote a stronger program;
  • Eliminate redundancy of efforts in tracking similar information, but maintaining flexibility to work with co-permittee; and,
  • Simplify the process of program updating, review, documentation, and reporting.
  • A consistent program may also simplify future permitting of MDT discharges from designated urbanized areas in the state of Montana once the current permit expires.

In some of the designated Small MS4 areas, the co-permittee (e.g. the city government) has agreed to be the lead agency with MDT providing technical or financial support, and implementing limited BMPs or portions of the shared SWMP. Generally, MDT will be responsible for implementing and maintaining elements of the shared SWMPs in their own jurisdictional areas unless otherwise stipulated in the agreements between the co-permittee agencies.