Roads were closed and riverside subdivisions were flooded Friday afternoon as the Rock River continued to rise in the wake of heavy rain earlier in the week.
The National Weather Service predicted that the river would crest in Byron at just under 17 feet, the highest level ever recorded.
Ogle County Sheriff Michael Harn said Friday afternoon that some roads were under water and closed to traffic.
"The highway department closed River Road because of the high water at Rock River Terrace," he said. "Right now, we're just watching the roads."
Water was also across Ill. 2 just north of Byron under a railroad viaduct, but the road was still passable. Water also lapped at the edges of Kishwaukee Road just north of Ill. 72.
Several subdivisions near the river, including Irwin Acres, north of Oregon, Brooks Isle, south of Oregon, and the Murray Subdivision, near Grand Detour, were flooded with their access roads impassable, Harn said.
Evacuations haven't been necessary so far, he said.
"We're checking the subdivisions to make sure to make sure people are okay," he said. "Most of them are very experienced at what to do after being washed out year after year."
A large storm system brought 4 to 6 inches of rain across Ogle County April 17-18.
The heavy rains began in the early hours of April 17 and continued for more than 24 hours, swelling creeks and streams and flooding fields.
Tributaries of the Rock, like the Leaf River, Pine Creek, and Kyte Creek came out of their banks early April 18, but had receded somewhat by that night.
"The water along the tributaries is subsiding somewhat, but we still have concerns about wash-outs," Harn said.