Water quality focus expands beyond Seven Mile Creek to safeguard wells

Jul. 30—ST. PETER — Progress has been made but challenges remain for Seven Mile Creek, located in the county park between Mankato and St. Peter.

Since the late 1990s, the creek and the 24,000-acre watershed that feeds it have been intensely monitored and significant funding put in place for water quality improvement projects.

Eric Miller, watershed technician with Nicollet Soil & Water Conservation District, said the watershed was a focus for a number of reasons.

"The creek's important because it's focused around Seven Mile Creek County Park. It's such a well-known creek because of the park and it's easy access from Mankato and St. Peter."

The creek is also one of only a few designated trout streams in the region.

Much of the work has been done by the Seven Mile Creek Watershed Partnership, a coalition of 25 agriculture, conservation, community, business, and government groups led by Great River Greening and Nicollet SWCD.

Miller said the SWCD is starting to shift more attention to a couple of watersheds west of St. Peter in an effort to reduce nitrates and other farm chemicals from getting into shallow aquifers that supply much of St. Peter's drinking water.

Meanwhile, Great River Greening is continuing to work with area farmers to promote best management practices, such as cover crops and planting Kernza — the first perennial wheat — to help reduce the amount of nitrates getting into the aquifers.

Laura Triplett, associate professor in geology and environmental studies at Gustavus Adolphus College, has for years been monitoring the Seven Mile watershed.

She needs to gather this year's monitoring data to statistically determine if and how much things have improved.

"For the past three years we have really good data on nitrates, E.coli bacteria, suspended solids and total phosphorus. This is the last year I'm doing intense monitoring with this (MPCA) grant, and we can take the average of these four years of monitoring and compare it to four years of pretty intense monitoring done about 10 years ago."

Triplett said averages from several years of monitoring is needed because a variety of factors can skew the data from one year to the next. Last year, for example, there were many major rain events that increased the flow in the creek and erosion down bluffs, while this year there's been little rain to carry pollutants into the creek and Minnesota River.

Whatever the data ends up showing, Triplett is happy to see growing interest by farmers to improve their practices.

"I'm excited there are some farmers in the watershed who are really curious about their land and water and being proactive about trying new things. They know the way we were doing things 10 or 20 years ago were really bad for the river, for the streams, the trout. And it affects the wells they all rely on, with nitrates in the water," Triplett said.

"Whether the changes made at Seven Mile are enough yet we hope to answer, but it's at least a hopeful sign that there's energy and interest."

St. Peter's concerns

Many of the same groups working on Seven Mile, including Nicollet SWCD, also teamed up with St. Peter to create a drinking water supply management area on the rich farmland to the west of St. Peter.

"We've put some funding into ag land practices that reduce or trap some of those nutrients rather than flowing into the ditch and into outlets that flow down to the city of St. Peter wellhead area," Miller said.

He said water coming off the tens of thousands of acres of crop land moves down toward St. Peter in a sandplain. "Everything that comes off the ag landscape goes down into those shallow aquifers. Three of the nine wells the city has are in those shallow aquifers. They're easiest to get water from but water needs more treatment (because of nitrates) and costs residents more."