Officials reported a slow drop in Fox River water levels following its crest in McHenry County over the weekend, but the possibility of rain Monday could erase any progress made.

Roads closed by floodwaters in recent days remained closed Sunday as the water slowly receded.

When and where rain could hit Monday, possibly bringing the river back up to major flood stage, still was the question Sunday afternoon, according to the National Weather Service’s Chicago office.

If the rain, including potential thunderstorms, comes through early Monday, that could deplete the fuel they’d need to develop stronger storms later in the day, meteorologist Gino Izzi said.

Or, there could be isolated heavy rains throughout the day. “Where that exactly hits is not sure thing. If it is upstream of [the McHenry County] area, it could be problematic at this point,” Izzi said.

It’s possible those storms – if they develop – could go to central Illinois, he added, and not bring more water to the Fox Valley.

When, where, and how much rain could happen Monday might not be known until the early morning hours. “The spectrum of what is possible is pretty huge,” Izzi said. “The overnight shift, 3 or 4 a.m., will have a better feel. Mother nature will tilt her hand then.”

The river had crested on the Chain O’ Lakes, above the McHenry Dam and at the Algonquin Dam, according to the Illinois Department of Natural Resources.

McHenry County Emergency Management Director David Christensen said Sunday that “it’s a slow watch on receding waters.”

While much of the Fox River and Chain O’ Lakes still were in a flood warning, as of mid-morning Sunday, that warning had been reduced to moderate flood levels at the Algonquin Dam. As of 9:30 a.m. Sunday, the river was at 11.9 feet. Major flood stage is anything over 12 feet below the dam.

Despite the progress made in some areas of the Fox River, River Road in McHenry and Rawson Bridge Road in Cary still were closed because of flooding as of Sunday afternoon. An up-to-date map of road closures can be found on the McHenry County Emergency Management website.

That page, mchenrycountyil.gov/county-government/flood-headquarters, was posted Friday. It provides information on topics from why people should respect barricades and road closures to what to do with sandbags.

“Turn around, don’t drown when encountering flooded roads,” a NWS report reads. “Most flood deaths occur in vehicles.”

The McHenry County Department of Health said Friday that people should wear personal protective clothing and equipment when sorting debris from flooding.

Sand or sandbags that have been in contact with floodwater should not be reused in ways that involve human contact, such as in children’s play areas or gardening.