The Minnesota Pollution Control Agency released four studies last week that list changes needed in water and land management to improve water quality throughout the 10 million-acre Minnesota River Basin.

One study that focuses on the Minnesota River and the greater Blue Earth River Basin calls for reducing sediment in the river by 50% by 2050. Main causes of sediment are bluff, ravine and streambank erosion and watershed runoff, according to the Total Maximum Daily Load report. Much of the annual sediment load occurs in the spring after snowmelt and during spring storms.

According to report authors, tile drainage, which alters basin hydrology, likely intensifies sediment erosion in near-channel areas. The agency also noted that flows have doubled in the Minnesota River over the last 80 years.

The other three TMDL studies focus on the Minnesota River-Mankato watershed, the lower Minnesota River watershed and the Watonwan River watershed. There also are Watershed Restoration and Protection Strategy reports on these regions.

MPCA will seek public comment on the reports through Sept. 20. In addition, the agency is holding an open house July 31 in Mankato for people interested in learning more about the studies and overall goals for the watershed. The open house will be from 4 to 7 p.m. at the Sibley Park Pavilion, 900 Park Lane.

Watershed work

In the TMDL study on the Minnesota River and Greater Blue Earth River basin, MPCA says the basin suffers from high turbidity, causing it to fail water quality standards that protect fish, insects and other aquatic life.

Sediment and other suspended materials in water can affect fauna by reducing visibility, clogging fish gills and smothering habitat. Sediment buildup affects navigation in the Minnesota River near the Twin Cities and threatens the long-term future of Lake Pepin.

Several stretches of streams in the Greater Blue Earth River also have bacteria levels high enough to violate the state water quality standard, indicating they are not suitable for swimming and other body-contact recreation. Restoring these streams will require reducing bacteria levels by 80% to 90%, MPCA says.

In other studies, MPCA says the Minnesota River-Mankato watershed, which is dominated by row crop agriculture, has water quality concerns regarding levels of sediment, bacteria, nutrients and chloride; the Watonwan River watershed has increased sediment levels due to erodible soils and higher river flows; and the Lower Minnesota watershed has elevated levels of nitrogen and phosphorus, and problems with excess sediment, bacteria and other contaminants.

MPCA Commissioner Laura Bishop said improving the Minnesota River’s water quality does not start or end with one community or industry. “Rather, it requires all of us to work together for the common good,” she said in a news release.

Farmers key in protecting water

Thom Petersen, commissioner of the Minnesota Department of Agriculture, says farmers are critical partners in local, regional and state efforts to protect water quality.

“Many farmers have implemented best management practices to keep soil on their land and out of water resources, including installing buffers and participating in the Ag Water Quality Certification Program,” he says. “To achieve additional water quality gains, we need more farmers and landowners to participate.”

Regarding runoff and sediment, Warren Formo, executive director of the Minnesota Agricultural Water Resource Center, notes that any increase in excess precipitation will cause runoff. However, he says modern drainage systems work on the landscape.

“We know that the first inch of rainfall, especially on dry soils, results in no runoff, but as soils become saturated, any additional rain can cause significant runoff,” he says. Ditch engineering and tile system design play key roles in handling peak flows.

“As aging drainage systems are being retrofitted, we can point to numerous examples in the Minnesota River Basin where a combination of additional tile combined with small water retention areas can provide the multiple benefits of reduced peak flows, cleaner water and more productive farms,” he says.

Learn more about the TMDL and WRAPS reports via the Minnesota River Basin portal on the MPCA website.

MPCA will respond to all comments received by the deadline. To ensure a response, include your name and contact information. The agency also will post all written comments and its responses on this website. Draft TMDL reports will be changed accordingly and sent to the EPA for final approval. MPCA will then implement TMDLs through wastewater and stormwater permits. WRAPS reports are approved by the MPCA Watershed Division director. WRAPS approval may take months, depending on number of comments received.