Mississippi River – Take a drink, then pass it on

In 1926, a survey of the metro Mississippi River between Minneapolis and Hastings found only two living fish. Today, the river is an award-winning bass fishery and home to 360 species of migratory birds.

What changed?

One hundred years ago, Pool 2 of the Mississippi River was nearly lifeless. Today, DNR biologists find 30 different species of fish, including giant flathead channel catfish.

In the late 1800s, the Mississippi River was a dumping ground for human sewage, garbage, and carcasses from the local slaughterhouses. Despite its highly polluted condition, the river was also the drinking water source for Minneapolis and St Paul. As a result, outbreaks of typhoid and cholera killed hundreds of people every year.

Eventually, in 1910, Minneapolis started treating its drinking water with chlorine. St. Paul eventually followed suit (though not until 1920!). This improvement helped to end typhoid and cholera but did nothing to improve the river itself.

Finally, in 1938, the Twin Cities built its first wastewater treatment plant on the Mississippi River and river water quality began to slowly improve. Later, with the passage of the Clean Water Act in 1972, the state and federal government began to regulate factories and industry discharging to the river as well.

1933: Sewage in the Mississippi River. Photo from Minnesota Pollution Control Agency

It is no exaggeration to say that wastewater treatment is a feat of human ingenuity and one of our most important 20th Century success stories. As the Mississippi River flows 2350 miles from Lake Itasca to the Gulf of Mexico, it passes through ten states and provides drinking water to fifty major cities.  In this way, we are continually passing water from one community to the next. St. Cloud is the first in line, drawing drinking water from the Mississippi, then cleaning and treating the resulting wastewater before it flows onward to Minneapolis and St Paul. Bizarre as it may be to contemplate, the very same molecules could flow through the bodies of people in Minnesota, Arkansas, and Louisiana.

Wastewater plants remove solids, treat to kill bacteria and viruses, and also filter water to reduce phosphorus levels in the effluent. Early on, stormwater and wastewater both flowed through the same pipes in Minneapolis and St. Paul. This caused problems during large rain storms, however, when the pipes would overflow and send untreated sewage straight to the river. Today, the Twin Cities is the only large city in the United States that has successfully separated all of its stormwater and wastewater, an accomplishment that has saved our area millions of dollars in regulatory compliance and reporting.

Wastewater treatment plants kill bacteria and remove phosphorus and pollutants before releasing water to lakes and rivers. Upgrading technology to remove chlorides and other emerging contaminants can be very expensive. (Photo of Western Lake Superior Sanitary District treatment facility in Duluth, MN)

Within Washington County, most communities send their wastewater to the Metro Treatment Plant in St Paul. In addition, 30,000 people in Stillwater and surrounding communities send their wastewater to the St Croix Valley Wastewater Treatment Plant in Oak Park Heights. It is the Met Council’s only wastewater treatment plant on the St Croix River. In addition, the Met Council operates the Eagles Point Plant in Cottage Grove, which serves 60,000 people.

Though wastewater treatment has improved dramatically over the years, there are a few pollutants that plants aren’t able to remove. These include chloride from water softener salts, pharmaceutical compounds, and microplastics. Until we develop better technology, you can help by reducing the amount of salt you use in your water softener, disposing of old and unused medicines at a drop-off facility, and purchasing a laundry ball to collect microfibers from fleece and other synthetic fabrics in your washing machine.

Washington County has free, anonymous drop-off sites for medications at government centers in Cottage Grove, Forest Lake, Hugo, Mahtomedi, Stillwater, and Woodbury: www.co.washington.mn.us/3029/Medication-Drop-Off

Today the Mississippi River support birds, fish and wildlife thanks to advances in wastewater treatment. View from Schaar’s Bluff in Dakota County.