Le Sueur Watershed


HUC: 07020011

The Le Sueur Watershed is one of twelve major watersheds that make up the Minnesota River Basin.  It is located within Blue Earth, Faribault, Freeborn, Le Sueur, Steele, and Waseca counties in south central Minnesota.  There are twenty municipalities in the watershed with Waseca having the largest contributing population to the watershed.

GIS data provided by the MN DNR and LCC-GIS Office

GIS data provided by the MN DNR and LCC-GIS Office

The Le Sueur watershed is approximately 711,838 acres (1,112 square miles), subdivided into 86 minor watersheds.  The Le Sueur River flows north and west from Freeborn County 111 miles to its confluence with the Blue Earth River.  An extensive ditch and tile system contributes to water movement throughout the watershed.

Major resource concerns in the watershed are sediment and erosion control, drinking and source water protection, drainage management, waste management, and nutrients.

Land Use

Agriculture is the predominant land use within the watershed, accounting for approximately 87% of the land use, followed by grass/pasture/hay (4%), forest (1.5%), and lakes/wetlands (3%).  In general, two-year corn/soybean rotations (or corn-on-corn) comprise nearly 93% of the cropped lands within the watershed. Native vegetation in the area prior to settlement was primarily tall grass prairie throughout the watershed; part of the northern section of the watershed was mixed tall grass prairie and deciduous trees.

LandUseLe Sueur

GIS data provided by the MN DNR and MN Land Management Center



97% Private Landowners
3.3% State
0.12% Federal
0.06% County


Soils in the Le Sueur watershed are primarily loamy glacial till with scattered lacustrine areas, potholes, outwash and flood plains.  It was formed during the Wisconsin glaciation in Minnesota with glacial till deposited from the Des Moines lobe. The landscape is nearly level to gently undulating with relatively short slopes throughout much of the watershed and the most northern portions can be described as gently undulating to rolling with relatively short hills.

The western half of the watershed lies primarily in the Blue Earth Till Plain.  The landscape is a mixture of gently sloping (2-6%) well drained loamy soils and nearly level (0-2%) poorly drained loamy soils.  In this area of the watershed, there is extensive artificial drainage to remove ponded water from the more flat and depressional areas. There is a moderate potential for water erosion on nearly half the lands (46%) in this portion of the watershed.

Soils in the morainal complexes are usually loamy in texture and a majority of them are moderately steep and well drained, although roughly one-fourth of the tilled lands are nearly level and poorly drained that require artificial drainage.  Cropped lands in these boundary areas have a high potential for water erosion.

 glaciallobesfromUSGSThe eastern half of the watershed is a mixture of glacial lake plains, till plains, and moraines.  Portions of this half of the watershed are located in the “glacial” Minnesota Lake Plain.  Landscapes located in the lake plain can be characterized as nearly level with poorly drained or very poorly drained clayey or silty clay soils.  This area tends to have extensive subsurface and surface tiling.  58% if the eastern half generally has low water erosion potential because a majority of the lands are not bordered by streams, lakes, or drainage ditches.

 The western, eastern, and southern boundaries of the watershed are end moraines; various ground moraines are also in the eastern half of the watershed.  These moraines display an undulating to hilly landscape with slopes from 2-12%.


The drainage network is defined by the Le Sueur River and its major tributaries: Big Cobb River, Little Cobb River, Maple River, Rice Creek, Beauford Ditch; other smaller streams, public and private drainage systems, lakes, and wetlands complete the whole drainage network.  Total length of streams is 1,201 miles of which 703 miles are intermittent streams and 498 miles are perennial streams.

Major Rivers and Streams
Le Sueur
Big Cobb
Little Cobb
Rice Creek
Beauford Ditch

Major Lakes
Lake Elysian
St. Olaf

*More extensive lists of all rivers, streams, and lakes in the Le Sueur watershed can be found at the MRBDC website*

Water quality information:
Monitoring stations have been established on the Le Sueur River and some of the larger tributaries. Water quality data comes from a variety of sources, such as volunteers with the Citizen Stream Monitoring Program, USGS personnel, or MPCA personnel. You can find more information on water quality data from the MPCA interactive map. In general, of the three watersheds which make up the Greater Blue Earth River Basin, the Le Sueur River watershed, along with the Blue Earth watershed, contribute a majority of the total suspended solids (TSS) and total phosphorus (TP) load. The Le Sueur generates the highest yield of TSS of the three watersheds that make up the Greater Blue Earth River Basin.

According to the MPCA website, the Le Sueur River watershed had the following water quality estimations:

2007-2009 Le Sueur – Average Loads, Concentrations and Yields






Flow Weighted Concentration (mg/L)





Load (tons/yr)





Yield (lbs/acre)





For further information check out the MPCA website here to see more water quality data.

Water quality standards have been developed for many pollutants, and often they arise due to human health concerns. They are developed by state and federal governments to indicate the extent of the pollution in a water body. This gives us threshold to determine when waters are impaired or not.  The following are several of the key water quality standards for rivers:


Fecal Coliform



Dissolved Oxygen

Total Phosphorus*


Water Quality Standard

200 CFU/100 mL

25 NTU

10 mg/L

5 mg/L


~60 mg/L

*There is no federal or state standard for phosphorus, often it is dependent upon and specific to the water body; The Minnesota River is estimated that a threshold of 0.26 mg/L is needed to reduce undesirable algal growth; EPA desired goal to prevent nuisance plant growth is 0.1 mg/L

Resource Concerns

Many of the waters in the Le Sueur watershed are on the MPCA impaired waters list.  The major concerns are aquatic recreation, aquatic consumption, and aquatic life caused by high levels of turbidity, nutrients, and bacteria.

Listed Stream/Reach


Affected Use

Cobb River: T104 R23W S34, south line to Little Cobb R

Turbidity, Fish IBI

Aquatic Life

Cobb River: T107 R26W S30, west line to Le Sueur R

E. coli, Turbidity

Aquatic Recreation, Aquatic Life

Le Sueur River: CD 6 to Cobb R

E. Coli, Turbidity

Aquatic Recreation, Aquatic Life

Le Sueur River: Cobb R to Maple R


Aquatic Life

Le Sueur River: Maple R to Blue Earth R

Acetochlor, Fecal Coliform*, Turbidity, Mercury, PCBs

Aquatic Life, Aquatic Consumption, Aquatic Life

Little Cobb River: Bull Run Cr to Cobb R

Fish IBI, DO, Fecal Coliform*, Turbidity, Mercury

Aquatic Life, Aquatic Recreation, Aquatic Consumption

Maple River: Minnesota Lk outlet to Rice Cr


Aquatic Life

Maple River: Rice Cr to Le Sueur R

Fecal Coliform*, Turbidity

Aquatic Life, Aquatic Recreation

Rice Creek: Headwaters to Maple R

Fish IBI, Turbidity

Aquatic Life

Unnamed creek (Little Beauford Ditch): Headwaters to Cobb R

Acetochlor, Fecal Coliform*, Turbidity, Mercury, PCBs

Aquatic Life, Aquatic Recreation, Aquatic Consumption

Listed Lake


Affected Use



Aquatic Consumption

Eagle: North


Aquatic Recreation



Aquatic Recreation


Nutrients/Eutrophication, Mercury*

Aquatic Recreation, Aquatic Consumption


Nutrients/Eutrophication, Mercury*

Aquatic Recreation, Aquatic Consumption

*Approved TMDL

Check out the MPCA Environmental Data Access for more information.

Soil Quality

Sheet and Rill erosion cause sediment delivery to water bodies and remove productive topsoil from agricultural areas. It also increases the potential for gully formation.

Wind erosion physically removes lighter, less dense soil constituents such as organic matter, clays, and silts. This removes the fertile part of the soil and can lower productivity.

Surface Water Quality

Excess nutrients, sediment, and bacteria in surface water bodies degrades water quality and affects aquatic life and recreation.

Groundwater Quality

Nutrients, organics, and animal and human waste pose potential water quality and health issues for groundwater from aging septic systems, feedlot runoff, agricultural runoff, and abandoned wells.

Links for more Information about the Le Sueur Watershed

MPCA Le Sueur Watershed
MRBDC Le Sueur Watershed
EPA Surf Your Watershed
MN DNR Watershed Assessment Tool

Reports and Publications concerning the watershed and/or basin

Le Sueur River Major Watershed Diagnostic Report
Le Sueur Rapid Watershed Assessment
Geomorphic evolution of the Le Sueur River, Minnesota, USA, and implications for current sediment loading
Minnesota River Basin 2010 Progress Report: Le Sueur River Watershed
Le Sueur River Watershed: Partners working to restore southern Minnesota River
Sources of suspended sediment in the Le Sueur River
An Integrated Sediment Budget for the Le Sueur River Basin, Final Report, June 2011
Le Sueur River Watershed Monitoring and Assessment Report
Le Sueur River Monitoring Station Information (2001)
Le Sueur Impaired Waters Map
Minnesota River Basin: Watonwan, Blue Earth, and Le Sueur River Watersheds