All municipal separate storm sewer systems (MS4s) in the state of Minnesota are regulated by the Minnesota Pollution Control Agency (MPCA). The MPCA authorizes discharges of stormwater under a permit for Dakota County and other small MS4s. The critical component of the permit is a 
Stormwater Pollution Prevention Plan (SWPPP), which outlines activities and becomes an enforceable part of the permit.
Dakota County continually seeks comments from the public on the effectiveness of its SWPPP as required by its MS4 permit. Please submit comments, questions, or concerns 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 reflected in the reach and extent of the County’s pollution prevention program. However, because stormwater from County roads mixes with stormwater from cities, elements like education and outreach involve partnerships with cities to ensure stormwater program goals are met.
Stormwater pollution prevention programs are required to 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, including 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 on the County roads and throughout local communities is a high priority for Dakota County.
2. Public Participation/Involvement
Dakota County partners with cities, recruits volunteers to participate in monitoring wetlands in the Wetland Health Evaluation Program (WHEP), and engages citizens in an annual public meeting on the County MS4 program each spring.
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 potentially increasing pollution. Dakota County’s goal is to ensure that illicit discharges are not being routed to the County road catchbasins and storm sewers.
“Illicit discharges” are any direct or indirect non-stormwater discharge to the storm sewer system, excluding exempted activities. Exempted activities are typically waters like lawn irrigation, sump pump discharges, and firefighting water, but may vary by local ordinance. Illicit discharges include illegal pipe connections draining to the storm sewers or dumping activities. For County roads, the most likely form of illicit discharge is illegal dumping of soils and sediment, dumping of concrete washout water and other building or construction materials, or washing of leaf litter and bulk debris into the roads’ storm sewer grates.
For observed illicit discharges on County roads, such as active chemical or petroleum product spills and other emergencies, concerned residents should dial 911 or contact the Minnesota Duty Officer at 800-422-0798 if the party responsible for a spill is unable to do so. Concerns about stormwater on city roads and streets should be reported to the appropriate city authorities.
4. Construction Site Stormwater Runoff Control
Dakota County must put measures in place to control runoff from construction sites and ensure that MPCA construction stormwater requirements are met. For its road construction projects in the MS4 area, the County completes an internal site plan review of erosion and sediment controls and works with the city in which a project is located to ensure local and watershed requirements are met.
Concerns regarding stormwater runoff from construction activities on a Dakota County road project in the MS4 area can be reported to the Transportation Department at 952-891-7000 or through the report a roadway concern website.
5. Post Construction Stormwater Management
Similar to construction requirements, Dakota County defers to local city and watershed requirements for post-construction stormwater management. Projects in the Dakota County MS4 area are designed in collaboration with cities and watersheds to ensure long-term stormwater management requirements are met.
6. Pollution Prevention/Good Housekeeping for Municipal Operations
The Dakota County Transportation Department 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 collaborates with cities to address surface waters designated as impaired by the MPCA because they do not meet water quality standards. MPCA assigns each storm sewer contributor with drainage to an impaired waterbody a goal for reducing pollutants in stormwater. Dakota County is committed to developing projects with cities to meet impaired waterbody goals, particularly when they can be completed as part of County road projects.
Information on all impaired waters in Minnesota and links to maps of impaired water bodies are available on the MPCA’s Minnesota’s Impaired Waters List.