By: Mackenzie Consoer
Lake Pepin is distinct from its surroundings, but not isolated from them. Water quality is intimately tied to land use in most of Minnesota and parts of Wisconsin, North Dakota, South Dakota, and Iowa. Despite 80-90% of the incoming sediment and phosphorus coming from the Minnesota River Basin (MRB), local efforts are still critical to the overall health of Lake Pepin and its tributaries. Fortunately, local tributaries are relatively healthy and, despite comparably low impact on Lake Pepin, stakeholders on both sides of the lake are taking aggressive actions to improve water quality even more.
The Minnesota Pollution Control Agency (MPCA) monitoring and assessment work has determined that the small local tributaries into Lake Pepin (Hay Creek, Bullard Creek, Wells Creek, Gilbert Creek, and Miller Creek) meet water quality standards for suspended solids, phosphorus, and nitrogen. The biological indices for fish and invertebrates were high and continue to support recreational trout fishing. While impaired for e-coli, which is common throughout southern Minnesota, the tributaries are overall thriving ecosystems.
Unfortunately, there is a lack of baseline monitoring data for the Wisconsin tributaries (Isabelle Creek, Rush River, Bogus Creek, and Pine Creek), but water conditions are certain to see improvements from recent mitigation efforts.
Despite healthy tributaries, it is important to strive for continued improvement. The tributaries do account for about 2% of the Lake Pepin sediment loading, with the majority occurring during 1-3 large events every year.
“In the summer, when you have big rainfalls, the tributaries will deliver sediment to Lake Pepin and the turbidity plumes are obvious to see,” says Rob Burdis of the Lake City MN DNR. The Upper Mississippi TMDL study, sets forth a 20% sediment reduction goal from local tributaries as part of the comprehensive plan to improve Lake Pepin. Local stakeholders are clearly taking this reduction challenge seriously and becoming a model for water stewardship across the broader region.
Since 2015, the Pierce County Land Conservation Department (PCLCD), partnering with the Natural Resource Conservation Service (NRCS) within the U.S. Department of Agriculture (USDA) in Wisconsin, has used a $1.5 million USDA-NRCS grant to help farmers in the Rush River Watershed implement hundreds of conservation projects. Cover crops have been popular due to a growing awareness of their agricultural and environmental benefits. Plus, farmers can experiment with them because there are very limited detrimental impacts. Cover crops act as natural weed control, reduce fertilizer demands, and improve overall soil health. Instead of bare fields this spring, farmers appreciated the green landscape blanketed with vegetation protecting against storm erosion. Local interest is so high that the Rush River Watershed project has been awarded more grant money to meet demand.
“There is no silver bullet in anything, but cover crops have the potential to make a big difference,” says Rod Webb, director of PCLCD, “It is exciting to see what’s happening throughout the country right now.”
In Minnesota, the Goodhue Soil and Water Conservation District (SWCD) is also working with farmers to align agricultural and ecological goals. Cover crops, crop rotation, and reduced tillage are becoming normal practices as more farmers experience benefits first hand. While producers with animals have been using them for years, cover crops are recently experiencing widespread adoption within corn and soybean fields as well. One landowner in Goodhue County planted 600 acres of cover crops last fall and his fields experienced significant runoff reductions during spring storms this year. Beau Kennedy, from the Goodhue SWCD, describes how mitigation is gaining popularity: “We’ve reached a tipping point. In 10 years, cover crops in combination with conservation tillage practices might be the norm.”
Of course, Minnesota stakeholders are also busy ensuring compliance with the 2015 State Buffer Law, which mandates 16.5 ft. buffers along all public ditches and 50 ft. buffers along all streambanks. As of this summer, Goodhue County had 60-80% buffer compliance. Most farmers, however, have been eager to work with their local SWCD to ensure compliance and recognize the value of streambank stabilization. Many are finding additional benefits to buffers by planting hay and alfalfa for grazing cattle.
Southeast Minnesota also contends with karst topography, essentially geological swiss cheese, in which large underground tunnels and caves form as water dissolves natural limestone. Karst formations can increase drainage, and create vulnerabilities for groundwater contamination. It exacerbates the land-water connection and demands extra vigilance from land managers. A Goodhue County famer was recently surprised by a sinkhole, 20 ft deep and the length of a city bus, that suddenly appeared in his field.
The steep terrain, with widespread ravines and bluffs, also makes the area particularly susceptible to large and erosive gullies. Farmers often seek assistance from the SWCD once gullies start interfering with agricultural operations. The Goodhue SWCD is using their drainage assessment maps to acquire Clean Water Funds for earthen dams that provide structural mitigation against erosive gullies. Water is stored behind the dam and then released slowly through the drainage pipe, which allows sediment to settle and mediates outgoing flows to be less erosive. In some cases, the projects can be approved and completed in only a few days and reduce peak flow stormwater discharge by 80-90%.
Bruce Kohlberg, a farmer in Hay Creek watershed, was excited to show off his new natural dam and describe how it has reduced erosion, protected his road, expanded land use options, and improved local water resources. He states, “I’m so grateful that the SCWDs are here to help landowners like me”. Meanwhile, the public should be grateful for farmers like Bruce because mitigation projects like his also help protect public infrastructure vulnerable to impacts from high flow events.
The Goodhue SWCD prioritizes dam construction in watersheds that have limited water storage (not many dams) and requires sound conservation tillage practices in upland fields to be eligible. By implementing erosion reduction strategies in their fields, farmers alleviate stress on dams, maximize sediment reduction, and extend the life of the project. Justin Watkins, from the Minnesota Pollution Control Agency (MPCA) says, “In working with the SWCDs, they made it clear through their prioritization that they don’t want to do extensive in-stream work, like stream restoration, in subwatersheds that don’t have sufficient upland treatment first. It is important to realize the best order to things.”
Rob Webb from PCLCD agrees, “We absolutely have to have both. However, if we are not implementing conservation practices on the lands draining into the streams, it’s not a good investment of dollars to try to increase habitat around streambanks.”
It takes decades to see mitigation outcomes, especially those taking place across a large scale and within dramatically altered watersheds. As Shawn Giblin with the WI DNR points out, “The Minnesota River is a heavy lift. You can’t just flip the switch. It takes time.” At some point, large-scale changes, including those to our economic systems, will likely be necessary to make the changes that are necessary.
In the meantime, Watkins from MPCA encourages us forward, saying, “You really have to think of non-point issues as a campaign. In Minnesota, things like the Buffer Rule and CREP [Conservation Reserve Enhancement Program] are really important developments that we need to appreciate and support. We don’t want to cut funding or dial back. We just need to keep at it.”
All and all, the road to improving Lake Pepin water quality seems to be uphill both ways. Good thing local stakeholders seem to have hardy hiking boots. With a problem this big, every step counts.