Combined sewer overflows are being identified as a potential source of sewage in the Little Calumet River. That shouldn't come as a big surprise.
Hammond Mayor Thomas McDermott Jr. said there's a difference of 2 million gallons between the sanitary outflow meter in Highland and Hammond's inflow meter near the Borman Expressway.
That's a big difference, especially when the issue is 2 million gallons of raw sewage leaking.
"We believe it seeps through the soil next to the levee wall on the north side and into the (Little Calumet) River," said Hammond City Engineer Stan Dostanti.
Hammond and Highland officials have said their meters have been calibrated.
But this is an issue bigger than a one-time leak, or perhaps a meter mix-up.
The issue is a reminder of the problem with combined sewer systems.*
Combined sewers, gathering both sewage and storm water runoff, were once all the rage, but now they are condemned as a source of contamination in our waterways.
Sewage treatment plants can't, and shouldn't be expected to, handle all that excess volume when a heavy storm hits.
"While it's not good to have any overflow, it's very common in Indiana," said Dan Goldblatt, spokesman for the Indiana Department of Environmental Management.
Of about 100 communities with combined sewer systems, "all but two or three communities at least have plans now to correct that problem," Goldblatt said.
Separating the sewers is a costly project. It involves ripping up streets and installing new sewers, then rebuilding the roads. And the sewers have to be routed to the right place, so sewage goes to the treatment plant and storm water goes to a legal drain that won't create flooding problems downstream.
Rebuilding sewer systems will take a long time to complete, primarily because of the expense, but it needs to be done. Raw sewage leaking into a waterway creates a health hazard. In fact, combined sewer overflows are one of the region's biggest environmental concerns.
And as the connection between Highland and Hammond shows, leaks can happen.
* This editorial has been changed from the original, to reflect that Highland's combined sewer system has been replaced by separate sanitary and storm water sewers.