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Le Sueur River Watershed Overview
 

• The Le Sueur River watershed is one of the highest contributors of nutrient and sediment pollutants in Minnesota.
   

• Because of the extensive changes to hydrology in the watershed, mainly drainage to facilitate agriculture and development, restoration of water bodies will hinge on holding back water and other ways to mitigate hydrologic changes.
   

• The Le Sueur River’s flow has roughly doubled over the past 60 years, partly because of increased precipitation but much of the higher flow is due to tiling and crop changes. This higher flow has led to higher erosion of bluffs, streambanks and ravines, resulting in high levels of sediment in the river. 
   

• Field erosion is also a major contributor of sediment, especially under high intensity rain events before crops are fully developed. 
   

• Other stressors in the watershed include lack of habitat for fish and macroinvertebrates; high nutrient levels that can cause algal blooms; and high turbidity levels that hurt aquatic life, recreation and aesthetics.
   

• Madison, Elysian, Eagle, Lura and Freeborn lakes are impaired due to excessive phosphorus that causes algal blooms and other problems.
   

• Sections of the Little Cobb River, Le Sueur River, Boot Creek, Cobb River, Rice Creek and County Ditch 3 are impaired due to bacteria levels or low dissolved oxygen levels. Significant reductions are needed in nutrient and bacteria levels for these waters to meet standards.
   

• Water quality in Minnesota has declined over many decades. While restoration activities continue, new problems develop, such as converting land to intensive cropping that negatively impacts water quality. The perpetual challenge is to make improvements and keep up with new problems. Consequently, it may take decades to fully restore impaired waters.
   

(Source: MPCA Le Sueur River Watershed Restoration and Protection Strategy)

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Land Use

Like most of southern Minnesota, land use in the watershed is mainly agriculture, covering approximately 83% of the area with an additional 4% consisting of grass, pasture, and hay ground. With approximately 1,800 farms in the area, the typical crops are corn, and soybeans with 93% of cropland being on a two year crop rotation (USDA, Rapid Watershed Assessment: Le Sueur). Small grains, hay, and grassland/pasture make up the remaining 7%. Residential and commercial development make up 6.5%, with wetlands and open water making up the rest. Nearly 97% of the land within the watershed is privately owned. There are approximately 780 registered feedlots located within the Watershed. All counties within the watershed are delegated to administer the Minnesota Pollution Control Agency (MPCA) Feedlot Program. Land use in the Le Sueur River Watershed has changed substantially since European settlement in the 1860s. Artificial drainage and tillage transformed natural native prairies and hardwood forests to agriculture land. These changes to hydrology left the area with an extensive ditch and tile system, both private and public. 

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Topography, Soils & Geology

Approximately 16,000 years ago the Des Moines lobe glacier covered the watershed. The retreat of the glacier left Lake Agassiz in its place in northwestern Minnesota, eastern South Dakota, and Canada. Eventually the River Warren was created at an outlet of Lake Agassiz, carving the Minnesota River Valley. From this valley, all tributaries, including those within the watershed, were formed. Soils in the watershed are primarily loamy glacial till with a high percentage of clay and silt. Course textured soils are located mainly in the lower reaches of the Le Sueur, Maple and Cobb Rivers. Geology is primarily glacial lake sediments to the west with ground moraine and stagnation moraine to the east, and minimal areas of outwash and alluvium. A county geologic atlas is completed for Blue Earth County and in progress for Waseca and Freeborn counties.

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Population
The total population of the watershed is approximately 37,000 (estimated from 2010 U.S. census data) and contains several rural cities including: Eagle Lake, Mapleton, New Richland, Wells, and small portions of Waseca and Mankato.
 

Largest Cities - Population:
Eagle Lake - 2,422

Wells - 2,343

Janesville - 2,256

Mapleton - 1,756

New Richland - 1,203