How the polluted Crow River is flooding the Mississippi

Cosmos, Minnesota – Carrie Jennings circulates around the South Fork Crow River like a water bug in the old one-seat canoe she bought years ago for $100, then pauses in the middle of the river to look out over the brown waters.

“This is insanely cloudy,” she muttered.

She’s come to check out this upper stretch of the Crow River as it begins its journey through agricultural country in central Minnesota to the Mississippi—showing how one small river can do so much damage.

The paddle comes as work begins on a new multi-county master water quality plan for the South Fork Crowe watershed under the state’s “one catchment, one plan” framework.

The stakes are high.

The Mississippi River, dear to the state, is clean as it appears in northern Minnesota and heads south. Then it meets the Crow River, the first major agricultural river to empty into, and its nutrient pollution doubles, state pollution officials say, adding phosphorous, nitrogen and sediment. You can see the water change at the intersection, some kayakers say.

The Minnesota Pollution Control Agency hung a greasy exclamation mark on the spot, near Dayton north of the Twin Cities, on its map of the top of the Mississippi.

Jennings, director of research and policy at the nonprofit Freshwater Association of St. Paul, points to some of the main reasons for this.

Large black plastic tubes protrude from the banks of the South Fork Crow River near Cosmos in Maker County, pouring water into them at nearly every bend. It’s tile drain water, coming from under the fields strewn with corn and soybeans here, about 80 miles west of where the crow joins the Mississippi.

An almost invisible network of pipes resembles an extensive underground highway system, draining water to maximize crop yield. The tile line drain carries agricultural chemicals—state pollution regulators say it’s the largest single source of nitrate in Mississippi, providing 43% of it.

Besides runoff, tile drainage also increases Crow volume. High flow streams hide in their banks, a dynamic only worsened by heavy rainfall due to climate change.

The scouring exposes the roots of enormous cottonwoods and other trees on the banks, many of which have fallen into the river. There should be a mixture of sand and gravel on the banks of the Crow River and downstream, Jennings said. Instead, there is thick black mud, like quicksand, that absorbs shoes.

Hollow riverbanks, as opposed to fields, were an increasing source of sediment in the Mississippi, she said. Still important, she said, dredging the topsoil from the fields, “the most massive increase was from non-field sources.”

Jennings said she expected to see brown water in the Minnesota River, the squalid agricultural river known to the state to the south, but not in the Crow River. And this is just the beginning of Crow. It only picks up more as it rolls downstream through heavy country like Renville County before joining the main Crow River at Rockford.

From there the crow runs into the Mississippi River, carrying its share of the pollution that drives the large, growing, oxygen-depleting “dead zone” of the Gulf of Mexico.

“If our farming system has been doing this in rivers yet in the watersheds of the Mississippi, imagine the cumulative damage by the time you get to the bay,” Jennings said. “This is not a mystery that needs to be solved. We know why these rivers are damaged and we know how to fix them.”

Agriculture is not the only source of crow pollution, but it is an important one. Sewage treatment plants and storm water runoff factor in the city. The bottom line is that the majority of the land in the Crow River watershed is used for agriculture, with cropping moving further north into Minnesota.

There are problems with agricultural practices such as the overuse of nitrogen fertilizers and manure, excessive drainage tiling with pipes that flow directly into ditches and streams, and over-plowing of the soil. East of the Cosmos, where Jennings row, the South Fork crow meanders naturally; Upstream is an abnormally straight farm drainage channel.

Because the Clean Water Act excludes sewage and runoff, environmental regulators rely on persuading farmers to voluntarily adopt best management practices: apply fertilizers more accurately, grow cover crops to capture more nitrogen in the soil and change tile drainage ports. One solution is to drain the tile water into a wet floor or sink first.

Such practices are still not prevalent. Change was slow. It could take decades, said MPCA’s watershed project manager Scott Lucas: “Lots of different things have to change.”

Large areas of each of the Crow’s main forks are still disabled for aquatic recreation or fish consumption, and for aquatic life such as insects. Pollution officials say that while there has been progress over the years in cutting phosphorous in the Mississippi River, there has been almost nothing to do with nitrate cutting.

Local farmers say they are aware of the problems and want to be good stewards of the land. But balancing conservation and production can be difficult when farm profit margins are poor. Changing established farming practices is difficult, said Joe Norman, a county technician for the Meeker County Soil & Water Conservation District.

However, the practices are slowly developing. For example, government programs have funded 81 wetland restorations in the South Fork Crow River watershed since 2004, according to state data. However, while they may benefit water quality, most are not the type designed to collect and treat tile drain runoff, said David Wall, an environmental research scientist at the Minnesota Pollution Control Agency.

Doug Adams, who farms 1,500 acres with his family near Cosmos, including land in South Fork Crowe, said he’s switched to strip tillage, disturbing the soil less and leaving plant debris on the surface for better soil cover. He said it has reduced its fertilizer use by 40%. It also keeps its surface soil in place and reduces runoff in the river, without changing its yield.

But shrinking his exchange system? Not an option. This spring, he said, was wet and late. The fields were flooded with water.

“I don’t know when we would be able to farm without the tiles,” Adams said.

Adams said he did not believe his court water was contaminated, and that he would not be afraid to drink it.

Cities, too, are making changes. Nearby, Hutchinson is embarking on a multimillion-dollar project to tackle the sediment and pollution that South Fork Crow carries into Lakes Otter and Campbell, two shallow lakes in the city. This means working with local landowners, supporting the banks of collapsing streams, restoring wetlands, and adding indigenous, buffer farms, among other things.

John Paulson, director of environmental regulation for the Hutchinson Project, said the Crow River’s impact on the Mississippi River is well known in the watershed world, but it’s hard to get people to care. Communities need to address the problem locally, where they can see it.

This is what Kandiyohi District did. It has just completed a decades-old project to restore wetlands in the large, drained prairie of the South Fork Crowe headwaters area near Willmar. More than a dozen families sold their permanent preservation facilities to the state to rebuild Lake Grass. Now carrying and filtering the farm’s drainage and Wilmar’s stormwater, Lauren Engleby, the Kandiyohe County Sanitation Manager, said. The large gate valve allows them to manage water levels.

Already, Engleby said, the frogs, turtles and birds are coming back. The waters of Grass Lake flow into Lake Wakanda and Little Kandiyohi Lake, which are weak lakes that are the official headwaters of the South Fork Crow River.

The real source of the river is the old Candy Mall parking lot in Wilmar, said Corey Nettleland, a DNR wildlife supervisor, who works in the area. The mall is built over a cow pasture made of drained wetland, and the parking lot pours into a large moat that extends into Grass Lake.

Engleby describes Grass Lake as a “big kidney” that is expected to significantly reduce nitrate, phosphorous, and sediment washing into the South Fork Crowe.

“That’s a big piece of the puzzle,” he said, “but it’s a very, very big puzzle.”

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