All municipal separate storm sewer systems (MS4s) in the state are regulated by the Minnesota Pollution Control Agency (MPCA). The MPCA authorizes discharges of stormwater under a permit for Dakota County and other MS4s.
The critical component of the permit is a 
Stormwater Pollution Prevention Plan (SWPPP). This outlines activities and becomes an enforceable part of the permit.
Dakota County continually seeks comments from the public as required by its permit. Please submit comments to environ@co.dakota.mn.us.
The Dakota County MS4 area is limited to the county road right-of-way in the urban area. This is reflectedthe county’s pollution prevention program. Because stormwater from county roads mixes with stormwater from cities, education and outreach involve partnerships with cities to ensure stormwater program goals are met.
Stormwater pollution prevention programs must have activities in six areas defined in the permit for MS4s called Minimum Control Measures (MCMs). The measures include:
1. Public Education and Outreach
Dakota County provides outreach through partnering organizations. This includes the Dakota County Soil and Water Conservation District (SWCD) and the Vermillion River Watershed Joint Powers Organization.
Example programs include Landscaping for Clean Water, a workshop to teach homeowners about raingardens, native gardens or stabilized shorelines, and a watershed model display for teachers to check out.
Educating the public on keeping leaves, dirt and trash out of storm drains is a high priority.
2. Public Participation and Involvement
Dakota County partners with cities, recruits volunteers to participate in monitoring wetlands in the Wetland Health Evaluation Program (WHEP).
3. Illicit Discharge Detection and Elimination
All MS4 permit holders are required to ensure that illicit discharges are not entering their storm sewers and reaching surface waters . Dakota County’s goal is to ensure that illicit discharges are not being routed to the county road catch basins and storm sewers.
Illicit discharges are any direct or indirect non-stormwater discharge to the storm sewer system. This excludes exempted activities like lawn irrigation, sump pump discharges and firefighting water. Exempt activities could vary by city.
Illicit discharges include illegal pipe connections draining to the storm sewers or dumping activities. For county roads, the most likely form is:
- Dumping of soils and sediment
- Dumping of concrete washout water and other building or construction materials
- Washing of leaf litter and bulk debris into storm sewer grates
If you see an illicit discharge, call 911 or contact the Minnesota Duty Officer at 800-422-0798. Concerns about stormwater on city roads and streets should be reported to the city.
4. Construction Site Stormwater Runoff Control
Dakota County must control runoff from construction sites and ensure that MPCA construction stormwater requirements are met. For its road construction projects, the county completes an internal site plan review of erosion and sediment controls and works with cities to ensure local and watershed requirements are met.
If you have concerns about stormwater runoff on Dakota County road projects in the MS4 area, call 952-891-7000 or report a roadway concern.
5. Post Construction Stormwater Management
Dakota County defers to local city and watershed requirements for post-construction stormwater management. Projects in the Dakota County MS4 area are designed with cities and watersheds to ensure long-term stormwater management requirements are met.
6. Pollution Prevention and Good Housekeeping for Municipal Operations
Dakota County Transportation manages street sweeping, road salt application and other maintenance activities. The county teaches maintenance professionals about stormwater pollution and improving maintenance techniques to minimize stormwater impacts.
Restoring Impaired Waters
Dakota County works with cities to address surface waters that do not meet water quality standards. When a body of water is designated impaired, the MPCA assigns each contributor a goal for reducing pollutants in stormwater. The county is committed to developing projects with cities to meet impaired waterbody goals.
For more information, visit MPCA’s Minnesota’s Impaired Waters List.