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Washtenaw County Stormwater Permit

What is stormwater?

Stormwater is the result of rainfall or snowmelt that flows over our lawns, streets, parking lots, and buildings. This water runs into storm drains and ditches and then directly into lakes, streams, and rivers, carrying the pollutants it picks up along the way.

Why should we care about stormwater?

As stormwater flows over lawns, driveways, parking lots and construction sites it is picking up pollutants such as: fertilizers, oil, yard waste, litter, animal waste, and anything else along the way. The storm drain system then transports these pollutants into the nearest lake, stream or river.  These pollutants may cause algae blooms, increased temperature, or contribute to the degradation of lakes, streams and rivers.

County Stormwater Permit

Water quality is paramount in Washtenaw County.  The county is situated within six different watersheds.  We are largely located within the Huron River Watershed, but portions of the county are within the Rouge River, Raisin River, North Branch Swan Creek, Stony Creek and Grand River watersheds.

Washtenaw County is one of several Huron River Partners working collaboratively on implementing several of the permit requirements. The collaborative approach is designed to accomplish stormwater quality improvements and provide an added benefit of cost sharing for some stormwater controls.  The partners include the City of Ann Arbor, City of Ypsilanti, Eastern Michigan University, Pittsfield Charter Township, City of Dexter, Ypsilanti Charter Township, and the Washtenaw County Road Commission.

Phase II Storm Water Regulations

In 1999, the EPA established the Phase II regulations to reduce the impact of pollution that was being created by increased development.  The permit was created to preserve, protect and improve the water resources from polluted stormwater runoff.  regulations require stormwater discharges from/>Municipal Separate Storm Sewer Systems (MS4) within the designated urbanized area, which are areas with populations greater than 10,000,Tree with web to obtain a permit from the Michigan Department of Natural Resources and Environment.  For a map of the designated urbanized areas in Washtenaw County, please click here.  The Washtenaw County Water Resources Commissioner’s Office administers the National Pollution Discharge Elimination System (NPDES) MS4 permit on behalf of Washtenaw County.  A copy of our latest report can be found below.

Per federal and state regulations, the MS4 permit requires urban communities to address both the amount of runoff and the pollution carried by that runoff that is deposited, untreated, into surface waters.  Under this permit, the county must comply with several requirements, which, if implemented, should result in a significant reduction in pollutants discharged to receiving waters.  The required components of the permit include:

Watershed Management Plan

The Middle Huron River Watershed Management Plan was developed in 1994, and was updated in 2000 and again in 2008. The plan outlines strategies to protect sensitive natural areas, mitigate impacts of existing point and non-point source pollution, and restore degraded areas in the Middle Huron Watershed. 

Stormwater Management Plan (SWMP)

The Stormwater Management Plan details the specific actions watershed partners will implement to meet the permit requirements. The SWMP has seven main pieces.

  1. Total Maximum Daily Load (TMDL): Municipalities must identify and prioritize actions to reduce pollutants in stormwater discharges to make progress toward meeting water quality standards.
  2. Public Education Program (PEP): Municipalities must develop a program to promote, publicize, and facilitate educational materials and activities on stormwater and pollution prevention. This plan was developed and will be implemented in partnership with other permitted communities in the watershed.
  3. Illicit Discharge Elimination Program (IDEP): Municipalities must develop a plan with mechanisms designed to locate and eliminate discharges into storm sewer from sources other than stormwater.
  4. Post Construction Stormwater Management: Municipalities must have a program requiring new and redevelopment projects to implement on-site controls that will reduce pollutant loads in stormwater runoff.
  5. Construction Stormwater Controls: Municipalities must have a regulatory mechanism in place for erosion and sediment control, as well as best management practices (BMPs) for preventing or reducing other pollutants associated with construction activity.
  6. Pollution Prevention and Good Housekeeping Practices for Municipal Operations: Municipalities must have an operation and maintenance program to prevent or reduce pollutant runoff from municipal operations.
  7. Public Participation Program (PPP):  Municipalities must have a program to facilitate the involvement of the Municipalities in the watershed and the general public in the revision of SWMPs.

Additional information

If you would like additional information regarding the Washtenaw County Stormwater Permit, please contact Heather Rice ( at 734-222-6833.

2017 Stormwater Permit Report

2015 Stormwater Permit Report

2013 Stormwater Permit Report

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