Municipal Separate Storm Sewer Systems (MS4)
Under the Alaska Pollutant Discharge Elimination System (APDES) stormwater program, operators of large, medium, and regulated small municipal separate storm sewer systems (MS4s) require authorization to discharge pollutants under an APDES permit and are issued individual permits.
A large MS4 is a system that is located in an area with a population of 250,000 or more. A medium MS4 is a system that is located in an area with a population between 100,000 - 249,999. Regulated small MS4s are defined as all small MS4s located in "urbanized areas" (UAs) as defined by the Bureau of the Census, and those small MS4s located outside of a UA that are designated by APDES permitting authority.
Alaska MS4 Permits
- Fairbanks, North Pole, UAF, ADOT&PF
- Fairbanks North Star Borough
- Fort Wainwright
- Municipality of Anchorage & ADOT&PF
- Port of Anchorage
- Joint Base Elmendorf-Richardson
All operators of regulated MS4s are required to:
- Obtain an APDES permit, and
- Develop a stormwater management program designed to prevent harmful pollutants from being washed by stormwater runoff into the MS4 (or from being dumped directly into the MS4), then discharged from the MS4 into local waterbodies
Stormwater management program should include measures to:
- Meet the standard of reducing pollutants to the Maximum Extent Practicable (MEP)
- Identify major outfalls and pollutant loadings
- Detect and eliminate non-stormwater discharges to the system
- Reduce pollutants in runoff from industrial, commercial, and residential areas
- Control stormwater discharges from new development and redevelopment areas
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