An environmental group says the Chicago River is one of the most endangered rivers in the country. American Rivers says public health is at risk because local water officials don’t disinfect sewer water before discharging it.

Ann Alexander is a lawyer with the Natural Resources Defense Council in Chicago. “Chicago has known for 100 years about the need to clean up sewage, because it’s why we reversed the Chicago River to begin with, to keep that out of Lake Michigan,” Alexander said at a Tuesday press conference. “The fact is we can’t have a world-class city like Chicago with a third-world river running through the heart of it.”

The Environmental Protection Agency is demanding that the Chicago River be made clean enough to swim in. But local water officials say that would cost billions. They also say swimming would be dangerous due to commercial boat traffic.

A state board could consider a new water quality standard later this week.