In accordance with the Minnesota Wetland Conservation Act the wetland management plan must be based on watershed boundaries.
“To the extent practical and feasible, the comprehensive wetland protection and management plan should be based on watershed boundaries. The size of watershed addressed should not be larger than is appropriate to ensure that the wetland resources provided through replacement will effectively compensate for approved impacts. For local governments with multiple watersheds, a separate analysis should be completed for each watershed substantially within the local government's jurisdiction.”
Natural features, such as lakes and rivers, play a significant role in the County’s development patterns, land management and conservation. The Minnesota River forms the Blue Earth County’s irregular, northern border with Nicollet County. More than 99 percent of Blue Earth County is located in four major watersheds within the Minnesota River Basin. Blue Earth County Watersheds Map
The County contains the confluence of the Watonwan River with the Blue Earth River, the confluence of the Le Sueur River with the Blue Earth River, and the confluence of the Blue Earth River with the Minnesota River in Mankato.
The portion of Blue Earth County in each of the four watersheds and the portion of each watershed in Blue Earth County is shown in the following table.
The Le Sueur River watershed occupies 48 percent of the County, the greatest amount of land coverage in Blue Earth County. The Le Sueur River watershed contains a number of relatively large tributary streams including the Maple River, Cobb River, Little Cobb River, and Rice Creek.
At the regional and Minnesota River Basin scale, the Le Sueur, Watonwan, and Blue Earth River watersheds are often combined and collectively referred to as the “Greater Blue Earth River Watershed.” The three watersheds of the Greater Blue Earth River Watershed cover more than 75 percent of the County’s total land area.
The Middle Minnesota River Watershed occupies 25% of the land area in the county. The Middle Minnesota River watershed lies on either side of the confluence with the Blue Earth River at the bend in the Minnesota River, upstream and downstream of the City of Mankato.
Two-square miles in the northeast corner of the County drains east to the Cannon River watershed.
Source: Blue Earth County Comprehensive Water Management Plan