Cedar River watershed: Keep the projects coming to keep reducing pollutants

Contact: Cathy Rofshus, 507-206-2608

Landowners and producers are working voluntarily to reduce pollutants in the Cedar River and its tributaries in southern Minnesota. And more of those practices are needed to help streams and lakes in the watershed, according to two draft studies by local partners and the Minnesota Pollution Control Agency. The MPCA invites comments on the studies through April 3.

Over the past decade, projects on farms and throughout small drainage areas have helped to reduce erosion and improve water quality.

One such project, led by the Cedar River Watershed District, consists of two areas to temporarily hold back stormwater that would normally flush pollutants to Dobbins Creek, a tributary to the Cedar River. Known as “Dobbins 1,” the $1.5 million project took more than two years to plan and involves multiple landowners.

“It’s our biggest one yet,” Tim Ruzek said of the project. He serves as the water planner and outreach coordinator for the watershed district and the Mower County Soil and Water Conservation District.
After a big rainfall, two earthen dams will detain stormwater over more than 50 acres — larger than Austin’s East Side Lake — helping improve water quality and reduce flooding. The project is expected to reduce peak flood flows by 82 percent immediately downstream from its structures, keeping about 134 tons of sediment and 218 pounds of phosphorus per year out of Dobbins Creek.

Additional projects will help address the major issues in the Cedar River watershed identified by the studies: Excessive levels of sediment, bacteria and nutrients. High levels of these pollutants can hurt aquatic life and recreation like fishing and swimming.

The studies also identified these additional stressors, often related to elevated pollutant levels, to fish and bug populations:

  • Lack of habitat
  • Low dissolved oxygen
  • Changes in stream flows

In addition, nitrogen is a growing concern in this watershed. Monitoring shows a significant increase in nitrogen levels in both the long-term and short-term. The Cedar River in Minnesota has some of the highest nitrogen concentrations in the state. Nitrogen levels are a priority concern because nitrogen can make water unsafe for drinking, and harms aquatic life.

The studies also looked at Geneva Lake in Freeborn County, a headwaters lake and the only naturally occurring lake left in the watershed. The study determined that phosphorus, the nutrient that grows algae, needs to decrease by about 13 percent for the lake to meet standards.

While strategies will differ across the watershed according to land and water characteristics, several common strategies would help improve water quality throughout the Cedar watershed, including:

  • Improve soil health through better management of nutrients in fertilizer and manure, reduced tillage, and growing cover crops. Better soil health would help reduce erosion and runoff from fields.
  • Control water within fields through controlled drainage practices and alternatives to drainage such as water storage areas.
  • Control water below fields by restoring wetlands, installing water and sediment basins, and managing channels and culverts.
  • Improve habitat by restoring streams to natural meanders, planting and maintaining buffers, and designing ditches to account for water quality.
  • Managing stormwater in urban areas.
  • Upgrading rural septic systems.

Because most of the land in this watershed is used for agriculture, that is where most of the strategies need to be implemented. For example, fertilizer management is a key strategy to reduce levels of nitrogen leaching from cropland to water resources.

Open for comment are the Total Maximum Daily Load (TMDL) study and the Watershed Restoration and Protection Strategies (WRAPS) report. They are companion documents that quantify pollutant levels, identify pollution sources, propose ways to return water quality to an acceptable level and describe protection strategies to ensure continued high quality water resources.

The documents are available on the MPCA's Cedar River Watershed webpage.

Comments on the draft reports should be sent to Bill Thompson, MPCA project manager, 18 Wood Lake Drive S.E., Rochester, MN 55904; or by email, bill.thompson@state.mn.us. For more information, call him at 507-206-2627. Comments must be received by 4:30 p.m. on April 3.

Written comments must include a statement of your interest in the report (specify which report, WRAPS or TMDL), a statement of the action you wish the MPCA to take, including specific references to sections of the draft report you believe should be changed, and specific reasons for your position.