Glen Ellyn studies ways to limit Lake Ellyn flooding

A consultant recommends that the length of Lake Ellyn's weir -- a device that influences how fast water can leave the lake -- be extended to help mitigate flooding there during major storm events. Daily Herald File Photo

A consultant's report recommends changes to Lake Ellyn in Glen Ellyn that would increase the man-made lake's capacity and could reduce the potential of flooding during storms.

But the recommendations still won't completely prevent the lake from overflowing, officials say.

The lake, located north of the village's downtown, holds stormwater for roughly a one-square-mile area, and discharges it through underground pipes to nearby Perry's Pond and the East Branch of the DuPage River.

The conclusions of the hydrologic and hydraulic study by RHMG Engineers were released this week after the village and park district commissioned the Mundelein-based engineering firm to look at lake capacity issues last August. They've sought solutions to lake overflows after major storms in July 2010 and September 2008 left the nearby park, roads and some houses flooded.

Already, two of the consultant's recommendations have been implemented, since there was no cost involved. They are:

• Lowering the lake's normal water level from 707.5 feet to 707 feet, which would allow an additional 4.5 acre feet of storage. It also wouldn't impact recreational use of the lake.

• Removing the restrictor plate on an outlet pipe that would increase the discharge rate from 23 cubic feet per second to 37 cubic feet per second.

A third change, to increase the length of the lake's weir -- a device that influences how fast water can leave the lake early on in a storm event -- would cost about $152,000 and require the approval of the village and park district boards.

Two other changes -- to raise the lake's high water level and to expand the footprint of the lake -- were discussed but ultimately determined not to be feasible, said Bill Rickert, president of RHMG Engineers.

In the case of the first, it could lead to the boathouse being flooded, as well as Duchon Field at Glenbard West High School and nearby roads.

In the second case, park land and mature trees could be impacted, while little increase in additional storage volume would be achieved.

Since the lake was dredged and expanded in 1991, the amount of water that comes into it has increased. The recommended changes "reboot the lake, in a sense, to meet its original design intent" in being able to detain stormwater from so-called "100-year" floods, said Bob Minix, the village's professional engineer.

But even if modifications are made to the lake, it still won't be able to contain a "48-hour critical duration" storm event, Rickert said.

Joe Sinopoli, a nearby resident to the lake, said the consultant's recommendations are helpful, though they might not solve all the issues. He said he is confident that local officials are doing everything they can to mitigate flooding.

"I think everyone is pleased that there are some solutions now in place and other ideas are being discussed. That's very positive," Sinopoli said. "I think most of the residents in the area are hoping the village does even more. When we bought our houses, no one thought a lake two or three blocks away was gonna come down our street."

The consultant, who presented the report to the village board this week, is expected to meet with the park district board May 15. Minix said the village, park district and consultant will discuss next steps after that point.