Minnesota River Basin: Impaired waters, TMDLs and water quality
A water body is “impaired” if it does not meet one or more of the federal Clean Water Act’s water-quality standards. The Clean Water Act requires the Minnesota Pollution Control Agency to identify and restore impaired waters.
The primary tool for addressing impaired waters is a pollution reduction plan called a Total Maximum Daily Load, or TMDL. A TMDL is the maximum amount of a pollutant a water body can receive without violating water quality standards. The TMDL process identifies all sources of the pollutant and allocates necessary reductions among the various sources. These reduction strategies form the basis of an implementation plan. Implementation begins once the U.S. Environmental Protection Agency (EPA) approves a completed TMDL.
Several water quality studies are underway in the Minnesota River Basin and throughout the state. See the links below for additional information.
For more information about the statewide impaired waters program, including a list of project contacts, visit the MPCA impaired waters and TMDLs page.
TMDL projects underway in the Minnesota River Basin
Several TMDL projects are currently underway and in various stages of completion in the Minnesota River Basin. The projects highlighted below have additional information available. Information on the remaining projects is in development and will be posted to this site as soon as it becomes available.
- Blue Earth River TMDL: Fecal coliform – addresses 21 impaired reaches in the Blue Earth River watershed for fecal coliform.
- Blue Earth River TMDL: Turbidity – In process.
- High Island/Rush River TMDL: Bacteria – In process.
- Minnesota River Basin TMDL: Turbidity
This project addresses impairments on 18 reaches of the mainstem and the lower tributaries. The project area begins near Lac Qui Parle in western Minnesota and ends at the city of Jordan near the Twin Cities metropolitan area. Work on the project began in the spring of 2005. A draft TMDL Report is expected in 2008. Turbidity is caused by suspended and dissolved matter such as clay, silt, organic material, algae and color. Turbidity limits light penetration and inhibits healthy plant growth on the river bottom. It also affects aquatic organisms’ gill functions, ability to find food and spawning habitat.
- Pomme de Terre TMDL: Bacteria/Turbidity – In process.
- Redwood/Cottonwood Rivers TMDL: Bacteria – In process.
TMDL projects completed in the Minnesota River Basin
Carver-Bevens-Silver Creeks TMDL: Fecal coliform (approved by the EPA on March 14, 2007)
Chippewa River TMDL: Fecal coliform. This project addresses 10 impaired reaches for fecal coliform bacteria in the Chippewa River watershed.
- Minnesota River Lower TMDL: Low dissolved oxygen. This project addresses an impairment in the lower 22 miles of the river during low flow conditions. During low flows, excess phosphorus generates algal blooms. Eventually, the algae die off and decompose. The decomposition process creates a shortage of the dissolved oxygen needed to sustain aquatic life.
- Minnesota River Basin Phosphorus Permit: Wastewater treatment facilities contribute approximately two-thirds of the phosphorus to the lower Minnesota River during low flows. One step toward implementing the TMDL is the Minnesota River Basin General Phosphorus Permit – Phase I. The permit regulates phosphorus discharge from over 150 wastewater treatment facilities in the basin.
- Yellow Medicine (South Branch) — Fecal coliform. This project addresses an impairment in the downstream section of the River’s south branch.
For more information
For questions about the Minnesota River Basin, contact Basin Manager, Larry Gunderson, at 651-757-2400.