Little Rock Lake TMDL

lrl bluegreenalgae

In the summer of 2007, Little Rock Lake experienced a large blue-green algae bloom, raising the concerns of landowners in the area. Minnesota Pollution Control Agency (MPCA) staff conducted aire and water quality monitoring during the bloom. Algal toxin (microcystin) samples collected were determined to be at a "high health risk" level according to World Health Organization standards. Due to the severity of the algae bloom, Little Rock Lake was put on the draft 2008 Impaired Waters List. This benchmarked the start of the TMDL study.


This study addresses an excessive nutrient impairment in Little Rock Lake with a goal of quantifying the phosphorus reduction needed to meet Minnesota's water quality standards in accordance with section 303(d) of the Clean Water Act. Early in February 2012 the U.S. Environmental Protection Agency (EPA) approved the Little Rock Lake TMDL.

 Little Rock Lake and Creek Watershed Protection and Improvement Plan (TMDL Implementation Plan), February 2013


Little Rock Lake TMDL Final Report


lrlaerialLittle Rock Lake is impaired primarily by non-point pollutant sources. There are two individual permitted (point source) Concentrated Animal Feeeding Operations (CAFO), over 1,000 animal units, within the watershed; however, both permits are held to zero for phosphorus allowance. Regulated portions of Watab Township, the Minnesota Department of Transportation (MnDOT Outstate) and Benton County cover a small part of the watershed. These Municipal Separate Storm Sewer Systems (MS4s) received a wasteload allocation (WLA) of 0.5 kg/day. Construction stormwater has a WLA of 2 kg/year (0.008 kg/day).


A daily average nutrient load reduction of 13.2 kg/day (29.10 lb/day) would be required to meet Minnesota's water quality standard for shallow lakes in the North Central Hardwood Forest Ecoregion. Load reductions relative to the baseline range from 54 to 69% for the individual tributaries discharging directly into the lake. A combination of external and internal implementation strategies are recommended for the restoration of Little Rock Lake, beginning with emphasis on external sources. In 2013 an Implementation Plan was developed to address stressors and their sources for both the Little Rock Lake TMDL and Little Rock Creek TMDL.


Updates on lake monitoring and outreach activities can be found on the Lake Status page. For more information on the Little Rock Lake TMDL, please visit the MPCA's Little Rock Lake TMDL page.


Project Contacts

Gerry Maciej
 Benton Soil & Water Conservation District
14 2nd Avenue West
Foley, MN 56329
(320) 968-5300 Ext. 3

  • Overall project coordination/administration
  • Technical team and stakeholder coordination
  • Water quality monitoring and data collection
  • Transfer of data and reports to MPCA and Subcontractors
  • Execution of contracts for all non-Benton SWCD work elements
  • Conducting public outreach and education activities
  • Assisting MPCA in public notice and public hearings
  • Assisting MPCA in responding to comments


Maggie Leach
Minnesota Pollution Control Agency
7678 College Road, Suite 105
Brainerd, MN 56425
(218) 316-3895

  • Development of QAPP and equipment training
  • Assistance on equipment selection, setup, and flow monitoring
  • Equipment troubleshooting and maintenance
  • Development of rating curves
  • Assistance in determining water quality goals
  • Providing leadership to the public notification/hearing process
  • Assisting the Benton SWCD in responding to comments
  • Submission of final documents to EPA


Little Rock Watershed Stakeholder Committee

  • Joe Wollak
  • Donald Meyer
  • Bernie Thole, Benton SWCD Board Member
  • Marvin Stangl, Morrison SWCD Board Member
  • Ed Popp, Langola Township
  • Chuck Popp, Graham Township
  • Diane Wojtanowicz, Watab Township
  • Lawrence Thell, Mayhew Lake Township
  • Ray Sieben, Buckman Township
  • Robert Stuckmayer, Morrill Township
  • Jeff Tiemann, Bellevue Township
  • Guy Spence, Little Rock Lake Association
  • Ken Nodo, Mid-Minnesota Trout Unlimited
  • Rick Schlichting, East Central Irrigators Association
  • Brent Czech, New Heights Dairy
  • Helen McLennan, Morrison SWCD Manager