The last time this much water fell this fast on Champaign-Urbana, it was free-swim time in Campustown.
Two days of storms on Aug. 11-12, 1993, dumped 6.88 inches of rain on parts of the city, sending the Boneyard Creek out of its banks, flooding basements across the city and creating the usual "lake" at Fourth and Green streets.
Since then, the city has built a huge detention basin to capture water overflowing the Boneyard Creek and encapsulated the stream as it runs through the campus area. It has built other detention ponds in southwest Champaign, taken control of the Phinney Branch drainage district, conducted a five-year inspection program to eliminate illegal sump-pump connections and embarked on a long-term plan to improve sewer lines and connections throughout the city.
Those measures apparently paid off this week when torrential storms Tuesday and Wednesday again deluged some Champaign-Urbana neighborhoods with more than 7 inches of rain, officials said.
To be sure, there were still plenty of flooded basements and intersections. The city of Champaign was swamped with calls from anxious homeowners, many of them north of Springfield Avenue and west of Prospect Avenue.
"You can think of it as rush-hour traffic for raindrops. They just can't get away fast enough," said Eleanor Blackmon, assistant city engineer in Champaign. "We had around 7 inches in two days, so that's a lot of rain to get out of the way."
But the huge Boneyard detention basin on Healey Street near Campustown did its job, she said. The water level in the basin greatly increased in 24 hours, from 15 feet to 39 feet, and – more important to business owners – no flooding was reported along Green Street.
Ten years ago, Blackmon said, "The Boneyard would have been out of its banks. You would have seen flooding in all the businesses that front on Green, and some that front on Healey. They probably would have had boats at Green and Fourth and Green and Third, or at least people wading in the water – which isn't a great idea."
Likewise, the Phinney Branch in southwest Champaign stayed within its banks, Blackmon said. The city paid the developer of the Ponds at Windsor subdivision to build extra detention ponds for the area, and a troublesome bridge at Hemlock Street was removed, she said. The timing of the storms also helped, with enough of a gap between downpours to allow water to recede, she said.
The biggest problems came in areas where the city hasn't gotten to planned drainage improvements, Blackmon said. The west fork of the Boneyard flooded parts of Market Street and other nearby roads, she said.
That area is slated for improvements similar to those completed in Campustown under the 20-year Boneyard Creek plan, she said.
And the northwest section of the city, which had the heaviest concentration of flooded basements, drains into the Copper Slough, which hasn't had a lot of capital improvements yet, she said.
The northern section of the two cities – the band between Interstates 72 and 74 – also got the most rain on Tuesday and Wednesday, said Jon Burroughs, climatologist at the Illinois State Water Survey's Midwest Regional Climate Center.
Though the official water survey gauge in south Champaign recorded 3.25 inches of rain during the 24 hours that ended at midnight Wednesday – itself a record for July 9 – unofficial numbers collected by the climate center's informal Boneyard Creek network showed wide variance across the city. Over the two days, Burroughs' gauge near Prospect and Bradley avenues showed 6.44 inches, WILL's had 7.13 inches and one in Mahomet topped 9 inches, he said.
"Most of the readings I found around town were 6 to 7 inches, so you're probably looking at a 25- or 50-year (storm)," he said.
High rivers may threaten crops
In the wake of the deluge, the National Weather Service at Lincoln has issued warnings about potential flooding in the state and in neighboring Indiana.
By tonight, one warning says, the Little Wabash River should be 1.4 feet above flood stage, and that will probably affect crops, said Illinois State Water Survey scientist Sally McConkey. McConkey said another warning predicts there will be minor flooding along the Sangamon River today, which will probably inundate the lowlands along Bridge Street in Monticello.
The Vermilion River's peak was expected to be short-lived. It was expected to crest at 4.6 feet above flood stage Thursday night but to fall below flood stage today.
"The flooding's going to be high, and it's going to be a problem for farmers, but it's a natural thing for rivers to rise out of the banks," McConkey said. "It's part of the process. That's why we try to keep people from building in flood plains. The Illinois River was really low earlier this year, but now it's rebounded, back to cresting three-tenths of a foot above flood stage."
Attica, Ind., is located near the banks of the Wabash River, which is carrying all the extra water deposited on fields in the state, up to about 15 inches in the past week in the Lafayette area.
Residents said they're hanging on even though the Wabash is running only about 3 feet below the U.S. 41 bridge that crosses the river heading for Williamsport, Ind.
"The water's way up, the sewage plant is having problems, and they were talking about closing the bridge, but now they're not going to," said deputy Attica city clerk Deanna Hutts.