If you're looking for a place to go swimming or fishing, avoid southwestern Minnesota.

A new state study finds all of the lakes – and most of the streams – in the state's southwestern corner are too polluted for swimming or fishing.

The Minnesota Pollution Control Agency looked at four watersheds that are part of the Missouri River Basin and found only three streams of the 93 they studied were clean enough to fully support aquatic life. None of the lakes met that standard.

The waters occupy six counties in the southwestern corner of the state. That's an agricultural region and the MPCA says farming practices are the main culprit behind the sediment, nitrates, and bacteria that are polluting the rivers and lakes.

The agency says cleaning the waterways will take changes in agricultural methods. Recommendations in a summary of their study include limiting access of cattle to streams as a way to help stabilize stream banks and control sediment.

The report also called for more study of the water pollution, and said collaborating with landowners will be essential to keep the farm economy moving forward without neglecting water quality.

What rivers were studied?

Minnesota has 81 watersheds (find yours here) and the Pollution Control Agency studies the health of each in a 10-year rotation.

In 2014 the agency looked at the four that are southwest of the hills known as Buffalo Ridge and flow into the Missouri River rather than the Minnesota or the Red. Those are the watersheds of the Rock River, the Upper Big Sioux, the Lower Big Sioux, and the Little Sioux.

The full MPCA report is available here.

The agency has 15 tips for how to reduce nutrients in lakes and streams, including five suggestions for farmers, five for city dwellers, and five for everybody.