Mississippi River: Wildlife making a comeback, but please don't swim

The newest State of the River report shows big increases in agricultural pollutants.

The newest State of the River report shows big increases in agricultural pollutants. Tom Reiter

A million people in the Twin Cities drink water pumped from the mighty Mississippi River, and more than 50,000 Minnesota kids play in it every year. 

At the same time, bacteria from manure runoff and sewer overflows keeps building in certain sections of the river, and the native fish are showing high levels of toxic chemicals.

In 2012, the National Park Service and the Friends of the Mississippi River came up with the first “State of the River” report to take the temperature of the river’s health. It inspired a number of changes, such as closing the Upper St. Anthony Lock to slow the spread of invasive carp and banning things like coal tar sealants statewide.

Four years later, the second State of the River report found that although wildlife like bald eagles, mussels, and fish are on the rise, so are pollutants like bacteria (which comes from human and animal feces), nitrate (cropland runoff), and chloride (deicing salt).

As a result, many parts of the river are unswimmable. From Dayton to St. Paul, disease-carrying bacterial concentrations are too high for truly safe contact, and folks are advised to keep even their dogs from splashing in since drinking that water could make them sick. From Inver Grove Heights onward, however, the Mississippi is safe to play in.

When it comes to eating the fish, the state Pollution Control Agency says it should be safe as long as people eat only the smaller, leaner species, and just a little bit at a time. There’s enough mercury in black bass, for example, to be an issue if it’s eaten more than once a week. Common carp holds so many PCBs -- industrial chemicals that cause reproductive, nervous, and immune problems -- that it should only be eaten once a month at most.

And that’s only in the stretches of the Mississippi lying outside of the Twin Cities. There’s not much data available on the toxicity of the fish found between the St. Anthony Falls and Minnehaha Creek, though study author Lark Weller of the National Park Service says she probably wouldn’t fear eating fish that came out of the urban river, were she not a vegetarian.