Developed land and its effect on stormwater runoff and management is a concern both within and outside of municipalities in the county. Concerns about the potential adverse effects of stormwater runoff on water quality include altered hydrology, pollutants in runoff and construction site runoff.

County Stormwater Pollution Prevention Program

The Municipal Separate Storm Sewer System (MS4) Program is mandated by federal regulations under the Clean Water Act.  The program has been delegated to the Minnesota Pollution Control Agency (MPCA) in Minnesota.  

MS4s are publicly owned or operated stormwater infrastructures, used solely for stormwater.  It includes curbs, ditches, culverts, stormwater ponds and storm sewer pipes.    The primary goal of the MS4 program is to improve water quality by reducing pollutants that enter these public systems and discharge into rivers, lakes and wetlands.  Common owners or operators of MS4s include counties, cities, townships and public institutions.  In Blue Earth County, the regulated MS4 communities include the cites of Mankato, Eagle Lake, and Skyline, Mankato Township, South Bend Township and Minnesota State University-Mankato as shown on the MPCA Mapping Tool.  

Construction Site Runoff Control

On December 12, 2017, the Blue Earth County Board of Commissioners adopted the MS4 - Construction Site Runoff Control Ordinance.  The Ordinance establishes standards and requirements for erosion, sediment and waste control measures to be taken during the development of and alterations to lands within the Blue Earth County MS4 area. It also establishes a Land Disturbance Permit and process to obtain the permit. 

Illicit Discharge Detection and Elimination 

On December 12, 2017, the Blue Earth County Board of Commissioners adopted the MS4- Illicit Discharge Detection and Elimination Ordinance.  The Ordinance regulates and prevents any non-stormwater or pollutants from being discharged into the stormwater drainage system as required by State and Federal law.