United States Environmental Protection Agency says The Grand Calumet River has the most problems of any river in the USA.  The Grand Calumet is located in Indiana-along Lake Michigan between Gary, IN and East Chicago, IL.
Post Tribune:

The interesting part in this article that caught my attention was The Grand Calumet and the Maumee have several similarities.   I believe reading that the sediment with problems runs about 8-12 inches deep in the Maumee.
While the Maumee has 42 (down from 44) combined sewer overflows (CSO’s) that average discharges 71 times per year, litterally spewing millions of gallons of toilet water into local rivers anually. Allen County is the only county that can have discharging residential septic systems. All other residential systems in the state use the soil to treat their wastewater and the effluent becomes groundwater (which may or may not recharge a stream somewhere down the line). Allen is the only county that can have a pipe from the systems to the stream and there are a lot of strings attached to that permit to be sure that the effluent that is going into the stream is clean -but oversight is always underfunded.
…a few highlights from the article that reflect our own waterways …
“Historically, industry and municipalities in the region used the river as a sewer for their waste. For about a century, steel mills and treatment plants have spewed untold amounts of heavy metals, pesticides, bacteria and pollutants that can cause cancer in humans into the river.”- both rivers
“Today, elevated levels of mercury, lead, cadmium and polychlorinated biphenyls lie buried in the Grand Cal to a depth of up to 11.5 feet below ground surface, according to the EPA. The river also has problems with oil and grease and too little oxygen. EPA estimates that the Grand Calumet River and Indiana Harbor and Ship Canal contain 5 million to 10 million cubic yards of contaminated sediment up to 20 feet deep.”
The Grand Calumet has 15 CSO’s discharging an extimated 11 billion gallons of raw wastewater into the harbor and river.  About 57% of that is discharged within 8 miles of Lake Michigan….contributing to E. coli and beach closings from bacteria.
Stormwater runoff and water leached out from 11 waste disposal and storage sites located within 0.2 miles of the river continue to degrade water quality.
Five Superfund sites, the most contaminated places in the nation, are located in the area. So are 423 hazardous waste sites. And more than 150 leaking underground storage petroleum tanks. Air pollution and contaminated groundwater also affect the river, EPA says.
Today, about 90 percent of the river consists of wastewater from industry and sewage from municipal treatment plants, EPA says.
When officials assess the health of a river, they judge it based on 14 possible “beneficial uses,” such as whether people can swim in the river or eat fish from it and whether the river has the variety of bugs that would be expected in similar places.
The Grand Calumet is the only river in the United States that’s impaired in all 14 possible ways, said Gary Gulezian, director of EPA’s Great Lakes National Program Office.
The Grand Calumet River and the Indiana Harbor Ship Canal were identified in 1987 as an “area of concern.”
“Until we address the legacy sediment, we won’t have a river that can restore itself and is safe for all, for the ecosystem and for human health,” said Dorreen Carey, director of the department of environment with the city of Gary. “But in the meantime, it’s always been my position there’s lots of things we can do to contribute to cleaning up the river.”
Stormwater runoff, NPDES & combined sewer overflows to the river need to be reduced.
– NPDES is a legal straight pipe discharge called a National Pollution Discharge Elimination System Permit – they need more oversight and fines for going over legal limits or spills.