Amid the rain that fell during a heavy thunderstorm Wednesday, the stress was clear on the face of people filling sandbags at Fox Lake's street department.
"It's going to be pretty bad," Police Chief Mike Behan said as he wrapped a sandbag with wire and twisted it closed. "Let's hope (the rain) stops."
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But the time for hoping has passed for officials along the Des Plaines and Fox rivers, and the Chain O' Lakes who shifted to preparing for flooding in the coming days.
While volunteers in Fox Lake, Gurnee and some other Lake County towns filled, stacked and delivered sandbags, communities downstream in McHenry and Kane counties put their own flood plans into place.
High water levels, swift currents and floating debris forced the Illinois Department of Natural Resources to close the Chain O' Lakes and Fox River system from the Wisconsin line south to the Montgomery Dam because of unsafe boating conditions.
"If Wednesday's storm was indicative of where things will head this week, the flooding will be serious," said Kurt Woolford, chief engineer and flood response manager for the Lake County Stormwater Management Commission.
Woolford said Lake County emergency management officials will meet in Gurnee to try to determine the extent of flooding. But the biggest unknown factor is how much water will fall from a large storm system moving slowly over Illinois.
The National Weather Service initially expected it would produce about 3 inches of rain Wednesday into Thursday. But after a thunderstorm dumped more than an inch of rain and some hail across Lake County in a three-hour span, Woolford said the weather service upped the rainfall total to about 5 inches by the time the storm clears out Thursday night.
That would push water levels to 3.5 feet over flood stage on the Des Plaines River in Gurnee, and about 2 feet over flood stage in Fox Lake, Woolford said. Those totals would be similar to what was seen in Gurnee in 2007, and in Fox Lake in 2008, officials said.
"This storm spreads out to Oklahoma, and it looks like it will sweep slowly across Lake County," he said. "It's unclear at this point how much rain we will get."
Because of rising water, counties and communities have issued flash flood warnings along the Fox River.
Algonquin residents in the flood plain were told sandbags were available beginning at 3 p.m. Wednesday, at the Algonquin Wastewater Treatment Facility at 125 Wilbrandt St.
Kane County emergency management directors said anyone who experiences flooding in their area should call 9-1-1.
DuPage County Stormwater Management said the rain could raise water levels on Salt Creek and the West Branch DuPage River enough to warrant running the county's mechanically operated flood control facilities.
In Gurnee, recruits from Naval Station Great Lakes mixed with volunteers to help fill sandbags to try to hold back any water spilling over the Des Plaines River banks.
"We came out to fill a need," said Karen Shimer, who was with her daughter, Stephanie. "We got the call and just decided to help out."
No evacuations have been ordered along the Des Plaines or Fox rivers, or the Chain, officials said. In Fox Lake, Kings Island subdivision was blocked due to high water, and Knollwood Park subdivision had signs on the road warning people of high water. Both are flood-prone neighborhoods.
The eastbound lanes of Grand Avenue in Gurnee were closed late Wednesday between O'Plaine Road and First Street, and westbound traffic was restricted to one lane in that stretch due to a flash flood.
In Libertyville, the village staff has also begun filling sandbags as a precaution.
"We don't want to make people freak out, but we don't want people to ignore it, either. It's going to be a steady rise" in area waterways, Woolford said. "We just want people to be aware and prepare. Roads are kind of a big concern. We don't want people to drive through flooded roads."
• Daily Herald staff writer Mick Zawislak contributed to this report.