BRIDGEPORT — As Northwest Side residents were ferried from their flooded homes after the Chicago River’s North Branch crested the riverbanks, the scene was more subdued on the South Side.
That’s because the man-made engineering systems keeping water levels of the South Branch at bay functioned properly, experts said.
It all starts up north.
Portions of the river in northern suburbs that feed into the North Branch are natural systems that aren’t controlled by locks in the North Channel, or they're on a separate stormwater system that's not a part of the Deep Tunnel, a still incomplete system of 109 miles of underground tunnels built for pollution and flood control.
The Deep Tunnel quickly reached capacity, and the northern portions of the river absorbed torrential rains and headed south.
"By the time it gets down to Albany Park, the river itself is essentially saturated,” said John Quail, director of watershed planning with Friends of the Chicago River.
"There's not a lot of room in river fore more water...and it’s all exacerbated because it’s a swamp we’re built on,” Quail said.
North Branch water flow measurements in Niles captured by the U.S. Geological Survey pegged the water flow as somewhere near 4,000 cubic feet per second, Quail said. A typical flow is about 130 cubic square feet per second, according to USGS data.
At the Bridgeport Art Center, situated on the east bank of the South Branch, workers in the galleries and studios expressed relief. The basement of the massive facility flooded in June 2010 after heavy summer rains and damaged documents and art work.
Gina Hutchings, an artist and Web design company owner who’s organized river cleanups, said the water levels had risen a few feet but there wasn’t a threat a flooding.
While inventory may have been spared this time, Hutchings said there were groups of wildlife outside the building affected by the rising waters.