By Jim Newton, Lake County News-Sun, September 17, 2019
Residents crowded in to see a presentation Tuesday on reported increases in rain strength and frequency in Lake County and the region, as well as a projected long-term continuation of that pattern and what it might mean for the future.
The coincidence that Grand Avenue, a major route through Gurnee, was closed due to flooding less than a mile from where the meeting was held was lost on no one. Lake County Board member Steve Carlson, one of the organizers of the event, noted that some attendees had to take alternate routes to reach the presentation at Warren-Newport Library.
Grand Avenue was opened to traffic again at about 2 p.m., according to village officials.
The Lake County Stormwater Management Commission hosted the presentation, which was initiated prior to the most recent heavy rains by a group that included Carlson, Lake County Board Chair Sandy Hart, Gurnee Mayor Krysti Kovarik and stormwater management officials.
Commision Chief Engineer Kurt Woolford said that according to projections by the Illinois State Water Survey, “13-inch rainstorms in the late century will be our norm.”
The commonly referenced “hundred-year storm” is a term used to describe a rainfall event so heavy that over a 24-hour-period, it should theoretically happen only 1% of the time, officials said.
For the past 20 years, the threshold has been defined as 6.5 or more inches of rain in a 24-hour period. In response to documented rainfall increases, the State Water Survey has updated that threshold for a 100-year storm to 8.5 inches, Stormwater Commission Executive Director Michael Warner said.
Three 100-year storms have occurred in Lake County in just the past 11 years, Warner said, occurring in 2017, 2013 and 2008.
Woolford said projection models show continued increased rainfall in Lake County’s future, and that new development regulations taking the increased stormwater into consideration will be adopted next year, including an increase in the required size of storm detention ponds and storm sewers for new developments in Lake County.
“We don’t want 200 new homes flooding down the road,” Woolford added.
“The planet is getting a little bit warmer, and when air warms up, it gets more humid,” Warner said, adding that our air has become 7% more humid slowly since 1750, but the impacts are now becoming obvious.
“We’re getting more rain,” Warner said.
Warner added there has been a larger occurrence of “extraordinary” storm events recently, and rainfall data shows a steady if bumpy increase in rain from 1900 to 2015 and beyond.
While officials study data and work on regulations to address the weather pattern changes, homeowners affected by flooding can improve their situation both inside and outside of their homes, Woolford said.
Among the improvements suggested by Woolford were extensions to gutter downspouts and sump pump pipes, which he said should both be used to deposit water further away from a residence. Many homes have foundations surrounded by gravel, Woolford said, and sealing those areas is another way to keep water out, as well as the use of special floor drains, landscaping and barriers to protect homes.
Literature was available for residents to take with information on home projects that can help avoid sandbagging in the future, as well as information on flood insurance, which officials said is subsidized by the Federal Emergency Management Agency and should be obtained by homeowners through their regular insurance company, officials said.
For the worst-case scenario — repeatedly flooded homes — the agency’s home buyout program is also an option. Under that program, the county purchases and razes flood-prone homes, replacing them with green open space to help retain water.
Warner said most homeowners who have taken advantage of the program move to new locations in Lake County.
Warner said the county has already purchased more than 200 homes and converted them to green space, and has received grant funding for an additional 12 home buyouts.
Another impact of increasing rains is increasing mosquitoes, said Michael Adam, senior biologist for the Lake County Health Department.
Adam told the audience that the bad news is several batches of mosquitoes are expected to hatch as a result of flooding this fall before cold water shuts them down. The good news, he said, is that the most common mosquitoes to hatch after heavy rains are floodwater mosquitoes, which don’t carry serious diseases such as West Nile virus, but he added there could be an increase in more dangerous mosquitoes as well.
More information on increasing rainfall impact is available on the Stormwater Management Agency website, lakecountyil.gov/4185.