Why icy weather could mean flooding

Freezing temperatures predicted for later this week could cause ice dams on the Fox River and flooding in Kane County, state officials said Monday.

As high water flows from the north, the area of concern is near the Northwest Tollway bridge in the Elgin and Dundee area, said Illinois Department of Natural Resources water hydraulist Rita Lee.

"We are trying to move as much water down river as possible in front of these ice dams and before the deep freeze hits," Lee said. "We have a couple of days of warmer weather and hopefully, we can get most of this water moved."

When flowing water meets ice dams, the water will move sideways over the river banks and onto land, she said.

"We slow down the flows when the ice dams start, but there is a lot of water up north that needs to move somewhere," Lee said. "We are doing what we can to avoid the problems."

Officials in Lake and McHenry counties are watching rising water levels on the river and Chain O' Lakes north of the Algonquin Dam. They say those levels should begin to recede without any additional rain.

"We're not really nervous at this point, but we are monitoring the water levels and keeping a close eye on it," said Ed Lescher, head of Fox Lake's Emergency Services Disaster Agency. "We are checking the lower subdivisions and have sandbags available in case it there's a problem."

According to the United States Geological Survey, Fox Lake and the rest of the Chain system is about 6 inches below flood stage, and water levels on the Fox River from Johnsburg through the McHenry Lock and Dam and to Algonquin are at flood stage.

Water levels in New Munster, Wis., topped out at 2 feet over flood stage Thursday evening and started dropping Saturday. Water levels on the Chain reached their highest point early Monday morning.

The National Weather Service predicts the next chance of precipitation is Wednesday night into Thursday morning, when there is a 50 percent chance of snow.

On average, the Chain rises and falls depending on the amount of precipitation across the entire watershed system.

The Fox Watershed starts as the Fox River near Milwaukee and runs south to the Illinois River.

Depending on how saturated the ground is, 1 inch of precipitation could add 1 to 6 inches to the Fox River. Should the Fox River rise north of the Chain, then the Chain will rise when the water makes it way south.

The Chain and Fox started rising last week due to heavy rainfall this month, coupled with melting snow.