Changes in water and land management are needed across the Minnesota River Basin for the state’s namesake river to improve in water quality, as well as streams and lakes throughout the 10 million acres of the basin, according to four studies released today by the Minnesota Pollution Control Agency (MPCA) and local partners.
Learn more about the studies and overall goals for the watershed at an open house on Wednesday, July 31, from 4-7 p.m., at the Sibley Park Pavilion, 900 Park Lane, Mankato.
The studies, funded by the Legacy Amendment, determined the Total Maximum Daily Load (TMDL) or the maximum amount of a pollutant that a water body can accept and still meet water quality standards. The standards are designed to make sure waters are fishable and swimmable.
Goal: Reduce sediment in river by 50 percent by 2030
One study concerns the major portion of the Minnesota River, focusing on Total Suspended Solids or sediment and other particles that cloud the water. The study calls for decreasing sediment in the river by 50 percent. The Minnesota River basin is a naturally vulnerable system with erodible soils, but some practices such as artificial drainage worsen the situation by bringing too much water at too fast a rate into the system.
Increasing flows are a major factor in the Minnesota River basin, accelerating erosion of river banks, reducing water quality and threatening infrastructure. In the last 80 years, flows have doubled in the Minnesota River.
It isn’t just an increase in precipitation causing increased flow; the river actually carries more water now per inch of rain than historically. Increased artificial drainage, reduced storage on the land (wetlands) and lack of perennial vegetation all contribute to higher flows. The end result is erosion of fields and streambanks that send sediment into the water.
The muddy water then makes it hard for fish and other aquatic species to breathe, find food and reproduce. The sediment is also filling in the Lower Minnesota River and even Lake Pepin downstream at a much faster rate than before European settlement – and intensive farming – of the basin.
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