Officials said Monday inspectors found three gates and anchorage systems at the dam broken.
They say the damage won't cause additional flooding risk to downstream communities. However, a decrease in water depth of the pool between Marseilles Lock and Dam and the Dresden Island Lock and Dam could lead to a decrease in navigation depth of the Illinois River and impact its usage.
Mike Cox of the corps of engineers says the dam is considered critical to Illinois River operations.
The mishap occurred when river currents resulting from last week's heavy rains redirected the barges toward the dam. Three of the seven barges sunk.
Rushing water burst over areas where grass used to be, runoff from the DuPage River pouring over the I&M Canal and into the state park until it receded Friday afternoon. Homes along the canal were at high risk.
Casey Gallegos' front yard usually looks, well, like a yard. But not Friday.
"This is a river in the park you know, it's out of control," she said.
Gallegos and her neighbors were asked to leave Friday when the water was still rising. At around 4 p.m. they were allowed back in.
The canal has flooded before, but it's only ever reached this level, over 11 and a half feet, once before, in 1996.
"When the water gets behind that dam like in '96 the whole dam gives way and water takes a rush through here, like a small tsunami that comes through here," said Channahon Mayor Joe Cook.
Another major problem area is I-55, where there is still water over the freeway, and it's been closed between I-80 and Route 6 for hours causing gridlock throughout the area.
"We got a lot of cleanup to do, but one of the things were going to do is talk to the state, the IDR, the governor's office, talk to them about making this dam a more permanent structure and something we can really trust from here on out," Cook said.
Channahon is going to be eligible for federal money to get the area cleaned up. After the water recedes, the village will ask residents to volunteer to help with the clean up efforts.
Statement from Ingram Barge Company spokesman Keel Hunt:
"After speaking with the Marseilles Chief of Police and the head of Search and Rescue, we learned that prior to the barge incident, the city had already decided that the flooding would overtop the levees which in some places were experiencing partial failure and seepage which caused the city to plan for a partial evacuation. When the barge incident occurred, it was believed that the location of the barges above the dam would impede flow of the river through the dam and so the decision was made to accelerate the evacuation in the event that the already certain flooding would occur earlier than anticipated."
The Associated Press contributed to this report.