Efforts made to protect Seven Mile Creek

Natalie Rademacher, The Free Press, Mankato, Minn.
·3 min read

Mar. 17—ST. PETER — A group is helping farmers adopt practices that reduce the amount of runoff from fields that ends up in Seven Mile Creek.

The Seven Mile Creek Watershed Partnership, a coalition of conservation groups and government agencies, is working to communicate practices to farmers that help them as well as protect local water systems.

"It's finding that balance," said Brad Gordon, southern Minnesota program manager for Great River Greening.

Much of this work is funded through a Minnesota Pollution Control Agency grant that focuses on implementing better farming practices in the watershed and communicating the impacts on water quality.

Seven Mile Creek drains water from 24,000 acres of Nicollet County farmland through the county park and into the Minnesota River. The amount of water that flows from the farmland into the creek and the amount of fertilizer used on the land greatly impacts the quality of the creek's water.

Phosphorus and nitrogen, two primary nutrients in commercial fertilizers, can create algae blooms in the water. Some of these blooms can produce toxins that harm fish and even humans.

Members of the partnership have been working with local farmers to install systems that capture runoff and implement crops that better hold nutrients in the soil, reducing how much of the nutrients can end up in the creek.

One of these practices, called woodchip bioreactors, involves creating a trench filled with wood chips that captures nitrates from the water and converts it to nitrogen gas.

Another practice involves increasing the use of cover crops, such as Kernza. It is a perennial wheatgrass that has a deep root system. The deeper roots help capture carbon and hold water and nutrients in the soil, reducing how much runoff escapes a field and ends up in the creek.

Growing Kernza and other practices have been gaining traction in the area in the past few years, in large part because of the efforts from these groups to communicate with farmers.

"Some farmers in the watershed are really excited about trying new things," said Laura Triplett, a professor at Gustavus Adolphus College.

Triplett and students at Gustavus have been gathering data from Seven Mile Creek to determine if the increase in these practices is improving water quality. The research is in its third year of a four-year grant.

The efforts appear to be working: Nitrate levels in the water have gone down since hitting a peak in 2013.

"It's really encouraging. It seems like the work farmers are doing is trending in the right direction," Gordon said.

It can be difficult to track exactly how much of a difference the projects have made, though, because rainfall varies year to year.

Several large storms occurred during the past couple of years that have increased erosion and runoff ending up in the creek. There was a mega rain event in July last year that dumped up to 11 inches of rain on some parts of the region in fewer than 24 hours, according to the Department of Natural Resources.

The heavy rain from the storm caused soil loss for local farmers and Seven Mile Creek Park sustained heavy damage from the increase in water flowing through the creek.

"The devastation in the park was astounding," Triplett said.

She said her work didn't start out being about climate change, but the extreme weather is impacting the findings.

After big rain events, farmers need to drain excess water from the fields to protect their crops, but the problem is that the drainage ends up in the creek.

"These big events are pretty likely to stick around for years to come so it's good to get some of these practices installed to help buffer against these rain events," Gordon said.

The partnership is trying to prepare for this drastic weather by finding more ways to hold water back so these practices continue to help farmers and Seven Mile Creek.