What’s in the River: Agricultural and yard runoff
Algae continues to bloom in the River Raisin near downtown Manchester
by Claire Pajka
Fertilizers contain added phosphorus and nitrogen to help plants grow, but unfortunately these nutrients don’t have the same positive effect on rivers that they do on fields. While they may help crops grow, if these fertilizers get into water, they can not only disrupt the natural balance of the ecosystem, but cause extreme growth and buildup of algae, some of which may even be toxic.
The River Raisin faces pollution from vastly different sources, as it runs through both urban industrial and rural agricultural areas. Unlike the PCBs and heavy metals contaminating the river from factories and industrial sources, nitrogen and phosphorous pollution comes largely from agricultural and yard runoff.
As a tributary to Lake Erie, pollution going into the River Raisin has effects on a grand scale, and the river was once a major contributor to the massive algal blooms the lake has seen since around the 1990s. Through conservation farming initiatives, the river has been able to lower its fertilizer output and lessen its hand in the creation of these toxic algal blooms. Microcystin, a toxin in certain blooms, can cause adverse health effects ranging from skin rashes and nausea to liver and kidney damage. Additionally, microcystin cannot be filtered out of water, and past blooms on Lake Erie have resulted in major shut-downs of water supplies, such as in Toledo, Ohio in 2014. In addition to toxicity and unsightliness, algal blooms can cause the water to be hypoxic – a condition where the water is so depleted of oxygen that it cannot sustain life – leading to major declines in fish and aquatic wildlife populations.
On the EPA Area of Concern website, the River Raisin has a list of significant environmental degradation types, called Beneficial Use Impairments. One of the BUIs, excessive algae and eutrophication, was removed from the list in 2013 after clean-up and monitoring determined that the Raisin had significantly improved that aspect of the environment’s health.
Farmers in Southeastern Michigan and the River Raisin watershed play a crucial role in protecting the water, and organizations like Farmer-Led Watershed Conservation (FLWC) have helped provide resources to farmers to make conservation practices more accessible. Katie Goplerud-Smith, from the River Raisin Watershed Council and FLWC, says that she understands that “some of these conservation practices won’t yield results immediately, which is why some farmers might be skeptical of trying them. The past few years have been financially tough for farmers, and it’s understandable that they might hesitate trying certain conservation practices. But the overall long-term effects of using these conservation practices does improve soil health and water quality. It may take time to rebuild the soil nutrients and structure because it was farmed conventionally for so long, but if a farmer is able to stick with their conservation practices, it will improve soil health for future generations to farm and continue to keep water in our rivers and lakes healthier.” These best management practices for conservation farming, such as using cover crops, conservation tillage, filter strips, and sediment management, can be found on the FLWC website here.
While the River Raisin has seen successes in decreasing algal blooms, the threat still remains with over-fertilizing and fertilizing before rainstorms. In addition to fertilizers themselves, yard clippings that flow into waterways and decompose also add nutrients that can lead to algal blooms. By avoiding fertilizers altogether or using organic slow-release fertilizers responsibly – as well as making sure that yard waste such as grass clippings don’t make their way into waterways – you can help lessen the burden of nitrogen and phosphorous in the River Raisin.
To learn more about the region’s big polluters and pollutants, keep an eye out for the What’s in the River? article series over the next few weeks.
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