(TNS) - Even as parts of the Chicago area were cleaning up from torrential rains that deluged waterways, streets and basements, the worst could be yet to come for some areas as stormwater flowing from the north could bring record flooding in the coming days.



The Illinois Department of Natural Resources said Thursday that unprecedented water levels flowing downstream from Wisconsin are expected to cause problems on the Chain O' Lakes and the Fox River — even with no additional rainfall forecast until late Saturday at the earliest.



"Flooding of this magnitude has not been seen before," a statement from the department warned.



The Fox River in New Munster, Wis., was headed to an expected crest Thursday at 17.4 feet — more than 2 feet above its previous record, the IDNR said. It has estimated that the river will send 13,400 cubic feet of water per second into the Chain O' Lakes system by Friday — "higher than we've seen on the Chain."



In anticipation, the Chain O' Lakes was expected to be closed down by Friday morning — portions of the Fox were already shut down Thursday — and owners were asked to remove boats from the water where possible. The Fox Waterway Agency warned that levels could eclipse those seen during severe flooding in 2008 and 2013.



Dams along the Fox River in McHenry and Algonquin were also opened to allow some of the water to flow south before the peak is expected to hit Friday.



A similar scenario was playing out along the Des Plaines River, which exceeded flood stage Thursday and was expected to crest Friday night at 5 feet above flood stage in Gurnee and Lincolnshire, and 6 feet above flood levels in Des Plaines.



Parts of Lake County received more than 7 inches of rain in the past two days, county officials said.



Farther south in Cook County, the Des Plaines River was expected to peak just above flood stage Friday night in River Forest and Riverside. As of Thursday, officials in both towns were not anticipating significant problems but had plans in place if the forecast changes.



The Fox River in McHenry and Algonquin also began flooding and was expected to keep rising through the weekend, peaking in Algonquin at 3.5 feet above flood stage by Monday night, by National Weather Service estimates.



In Chicago, the north branch of the Chicago River rose to about 5 feet, below the flood stage of 7 feet, and was expected to drop.



Flooded areas generally dodged additional rains Thursday, and cooler, drier weather was forecast, with no more precipitation until at least Saturday night. But Lake County officials warned that "major flooding" could still get worse as water flows from Wisconsin.



Late Wednesday, Lake County Board Chairman Aaron Lawlor signed a proclamation declaring that the severe flooding had created a disaster. The state-of-emergency proclamation was sent to Gov. Bruce Rauner and the Illinois Emergency Management Agency, according to a news release from the county.



"The past 24 hours have been very challenging for the residents of Lake County as we respond to the flood," Lawler said. "Once the waters recede, recovery, cleanup and damage assessment will continue for weeks. It's important to remember we are all in this together."



Wisconsin Gov. Scott Walker also declared a state of emergency Thursday for the southern counties of Kenosha, Racine and Walworth. He traveled to Burlington, Wis., to survey the damage and called the Wisconsin National Guard to active duty as necessary to help local recovery efforts.



Downstream of Burlington in New Munster, William Glembocki, town chairman of Wheatland, said it was the worst flooding he'd ever seen, with hundreds of homes flooded. Roads were washed out, and Highway 50 was closed at the Fox River.



"We're in a world of hurt up here, but we're going to get through it," he said. "You guys in Illinois are gonna get it from us here soon."



Another casualty of the flooding was Northwestern Medicine Lake Forest Hospital, which had to shut down clinical operations late Wednesday because of a weather-related power outage.



Power was restored to the hospital Wednesday night, but the facility remained closed to clinical operations Thursday.



In total, 93 patients were transported from Lake Forest to Northwestern Memorial Hospital in Chicago and other local facilities, and it remained unclear late Thursday when normal operations would resume.



Many roads in Lake County remained closed by the flooding. Details are available at www.lakecountypassage.com.



The College of Lake County and Six Flags Great America in Gurnee were forced to shut down Wednesday because of the weather but reopened Thursday. Oakton Community College's main campus in Des Plaines remained closed Thursday.



The local American Red Cross chapter closed its Chicago shelter Thursday but kept open three shelters for flood victims in Grayslake, North Chicago and Round Lake Beach.



Only a few people stayed at the shelters overnight Wednesday, which volunteers took as a sign that the recovery is going well.



The agency is distributing cleanup kits that include industrial brooms, a mop and bucket, cleaners with bleach, cloths and a tarp.



For help, call 847-220-7495, or download the free Red Cross Flood App at http://www.redcross.org.



rmccoppin@chicagotribune.com



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