MPCA reports show need for dramatic reduction in soil entering rivers

The Minnesota River connecting with the Blue Earth River
The Minnesota River is seen connecting with the Blue Earth River, center, in Mankato. The MPCA said suspended sediment in the Minnesota and some other area rivers need to be cut by 50 percent to meet federal standards.
Alex Kolyer | MPR News 2011

By Tim Krohn, Mankato Free Press

The Minnesota River and three major watersheds in the region have problems that run wide and deep, from excess phosphorus, nutrients and other pollutants to major loads of sediment that are choking rivers with suspended solids.

The report calls for the need for a whopping 50 percent reduction in sediment going in the Minnesota River and greater Blue Earth River.

“It means widespread changes if we want to meet goals,” said Wayne Cords, Minnesota Pollution Control Agency regional manager in Mankato.

The MPCA Monday released reports that lay out the problems in the rivers and how far over federal standards the rivers are. It also points to strategies for reaching the standards.

After a 60-day public comment period, those reports will go to the federal Environmental Protection Agency for review and acceptance. A public open house to review the plan is July 31 at Sibley Park.

Muddy water flows over Minneopa Falls
Muddy water flows over Minneopa Falls. The MPCA said suspended sediment in the Minnesota and some other area rivers needs to be cut by 50 percent to meet federal standards.
Courtesy of MPCA

The MPCA said higher river flows aren’t just from increased precipitation. The river actually carries more water now per inch of rain than historically. Increased artificial farm drainage, reduced storage on the land (wetlands) and lack of perennial vegetation all contribute to higher flows. The result is erosion of fields and streambanks that send sediment into the water.

“The Minnesota River is a historical, cultural, economic and recreational asset for Minnesota,” MPCA Commissioner Laura Bishop said in a press release. “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.”

The studies also point to multiple water quality problems in the Watonwan River watershed, the middle Minnesota River watershed and the lower Minnesota watershed.

Streams in the Minnesota River and greater Blue Earth River basin suffer from high turbidity: Soil and other particles muddy the water so that it often fails to meet water quality standards that protect fish, insects and other aquatic life.

Reaching standards will require sweeping changes in agriculture. “The finger gets pointed at agriculture, but it’s not that they’re bad, it’s just that it’s the largest land use,” Cords said, noting 80 percent of the 10 million acres in the Minnesota River Basin is farmland.

He said the agency is often criticized by agriculture as “wanting to put everything into prairie.” But he said that’s not the case. “It will take widespread best practices across the basin.”

Kevin Paap, president of the Minnesota Farm Bureau, said farmers are working to adopt best practices.

“In agriculture, we’re all about continuous improvement. That’s why farmers are investing their own money and working with the university and other groups on what works on a full scale and continue to look at those new, innovative things. We have to make sure we’re all at the table.”

He said farmers know cover crops are good for the soil and keep it on the landscape but said it can be a challenge for corn and soybean farmers.

“The hard part in Minnesota is we have a short growing season and it can be hard to get those established. If we have trouble getting our crops off (in the fall), it’s hard to do cover crops,” Paap said. “Agriculture is looking at alternatives and how they’ll work.”

And he noted that in extremely wet years like this one, keeping water and soil on the landscape is more problematic.

“When the soil is so saturated already, the rain can’t soak in and it runs off.”

Voluntary efforts

While none of the area watersheds or Minnesota River meets standards in a variety or areas, the Clean Water Act does not generally allow for regulatory action against “nonpoint souce” pollution, which includes runoff and erosion. “Point source” pollutants — typically things like a pipe coming out of a factory or a city’s wastewater treatment plant — are regulated.

But states are required to develop programs to manage nonpoint source pollution and meet standards if they want to get certain federal funding.

Water quality samples
The photo shows tap water on the left, the goal for area rivers next, the average of current water clarity over a year and the far right shows the dirtiest water at a given time. The three jars on the right are filled with water taken from the Le Sueur River at different times of the year.
Photo courtesy of MPCA

Cords said the agency will continue to look for voluntary efforts to eventually reach goals. “Things have changed so much, the climate and how we’re taking water off the landscape. We need bigger changes to address it.”

He said for now, the biggest benefit would be increased cover crops on farm fields during each spring. Most of the sediment is delivered into the river in three to five melt or rain events in early spring, from the time snow melts until about mid June, Cords said. Once crops are up and rooted in the summer, they are better able to slow runoff and take up water after even heavier rains.

“If cover crops are there in the early spring, that helps a lot.” And, he said, cover crops and low tillage practices add organics to the soil, which makes soil healthier. “The sign of the healthiest soil is soil you don’t see because it’s always covered with vegetation.”

And more organics in soil traps more water without affecting crop growth. For every 1 percent of organics in soil, 1 inch of rain is held for long periods in the soil, he said.

Cords, who has a small farm where he grows mostly canning vegetables, has worked to add more ground cover, but he knows the earlier harvesting dates of those vegetables gives him more time to add a cover crop than corn and soybean farmers who harvest late in the year.

“Everyone has to find what works for them.” He said going on farm tours and reaching out to the University of Minnesota, Soil and Water Resource boards and other agencies that work with best practices can give farmers ideas they can use on their farms.

Cords said that even fairly small but widespread changes have a cumulative effect. Agriculture usually cites acceptable loss of topsoil on farmland, for example, at 5 tons per acre. That’s the loss of soil that is just the thickness of a dime, something unnoticeable. But Cords said, add that 5 tons per acre times the millions of acres in the basin, and it’s a big issue.

Cords said city dwellers, businesses and others also need to do what they can to reduce the problems. “It’s not just people who live along the river — it’s everyone.” Cities are required to manage their stormwater so it goes into the rivers slower. Businesses can try to reduce the size of impervious parking lots and add more vegetation. Individuals can collect water in rain barrels or plant rain gardens to capture more rain.

Public input

The MPCA is seeking public input on the reports from now until Sept. 20. Those comments will then be reviewed and possible changes made to the final reports before they are sent to the Environmental Protection Agency.

Cords said they encourage people to comment and to include ways to help meet the federal standards. He said the EPA demands “reasonable assurance” that the plans the state has put together will eventually allow water standards to be met.

“The progress early on will be slow, but we will get there,” Cords said. He said that early adopters of best practices have been adapting methods now that will be much more widely accepted as more learn about them.

Sediment and other suspended materials (referred to as total suspended solids or TSS) in water can affect fauna by reducing visibility, clogging gills and smothering habitat. Sediment buildup also affects navigation in the Minnesota River near the Twin Cities and threatens the long-term future of Lake Pepin.

Cords said particular attention will need to be paid to the Le Sueur and Blue Earth watersheds because they contribute so much of the sediment in the Minnesota River.

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