Protect Our Rivers Blog

Steven Mercurio is Professor of Biology and Coordinator of the Toxicology Emphasis at Minnesota State University in the Department of Biological Sciences in Mankato, MN. His research interests are Environmental Toxicology and the effects of obesity on the toxicity of medications.

I have had a first-hand view of the Minnesota River since coming to Minnesota State University, located at the bend in the river at Mankato. It was a clear river in pre-settler times and had many wetlands to mitigate flooding. Since those times, though, the area has been converted into an intensive agricultural landscape and economy. We benefit financially from the crops grown in the region, but also have the negative consequences of poor stewardship of the lands and waters.

Dr. Beth Proctor, Coordinator of the Environmental Science Program, and I were invited to join the Minnesota River Assessment Project by Henry Quade, founder of the Water Resources Center at Minnesota State, with researchers from government and other higher education institutions with an interest in the Minnesota River and how it became the major polluter of the Mississippi River as it empties at St. Paul. Also, the sediment of Lake Pepin that is filling in that lake and creating an unintended “Minnesota River treatment facility” out of the lake is a major consequence of a lack of erosion control. These are the reasons that the Minnesota River Assessment was performed – to aid St. Paul in reducing pollution from the Minnesota River and to create healthier waters that might attract more recreational use of our valued surface waters in Minnesota. 

We found nutrient inputs from fertilizers that were being used in southern Minnesota and Northern Iowa in the final report of 1993. The Blue Earth River as it entered the Minnesota River was clearly a problem. My role was to look for persistent industrial chemicals, PCBs from old transformers, that had made their way into the fish populations. My research team of graduate students and undergraduates found significant levels of PCBs in the fish and biochemical signs that the fish livers had indeed been impacted by the presence of those PCBs (liver metabolism changes).

Since that time, many of us at the university have gone time and again to the river to check for pesticides, nutrients, and other pollutants in the Minnesota River Watershed. We wish the original intention of a major cleanup had been achieved, but now we see the effects of changing to an increased corn agriculture with more land in production that is truly marginal at best (including phosphorus-containing waste water from corn ethanol plants located on or near the Minnesota River). The liver toxicity of cyanobacteria (blue-green algae) due to microcystins is also becoming more of an issue for local lakes and the river. Many are also still using the river valley as a dumping ground for old tires, etc.

Although the City of Mankato is using the riverfront more, with the development of an amphitheater park downtown (as well as Sibley Park and the Land of Memories Park), the Minnesota River continues to be a challenge. It is of interest to us who drink from the taps in Mankato as well, as a portion of that water comes from shallow wells under the bed of the Blue Earth River. The methemoglobin research done by the National Institutes of Health picked this area as one of its sites of interest, as high nitrate/nitrite levels in agricultural wells (and certain municipal water supplies) cause fetuses and babies to oxidize the hemoglobin in their blood, making them less able to use oxygen from the air (methemoglobin does not bind oxygen).

It is important to be able to have an agricultural economy, safe drinking water, ability to fish and eat fish out of the river, and have other recreational uses of the Minnesota River as our heritage as Minnesotans without concern about our children’s health, our health, etc. I still enjoy sampling with students at the river and seeing the eagles nesting and other wildlife in and around the river. The natural beauty of the river valley is a spiritual resource to many who canoe or walk along stretches of the river and it is something we should be doing more to protect.