Engineers studying how the Kimball Street dam’s removal could affect Elgin’s water supply found lower Fox River water levels shouldn’t impact the intake system unless there’s extreme erosion.
But it’s difficult to know how much erosion would occur without further study, consultants told the Elgin City Council.
More data and models to forecast how the river erosion could occur will be developed under a contract amendment the council approved last week with Engineering Enterprises Inc. and the University of Illinois Department of Civil and Environmental Engineering. The additional work will cost the city $338,028.
“We have to get this right,” Councilman John Steffen said at the meeting. “We have to make sure we don’t jeopardize our water supply.”
Last year Elgin hired the engineering firm and the university as consultants to evaluate the U.S. Army Corps of Engineers’ Fox River Connectivity and Habitat Study, a draft report issued in 2023 that recommended nine dams along the Fox River be removed to restore the river’s natural flow and ecosystem.
The university used a “fixed bed” hydraulic model that showed the riverbed and channel will remain in place were the dam demolished.
However, consultants suggested creating a two-dimensional model that uses a “moveable bed” hydraulic model that predicts how the erosion would affect sediment movement and potential channel location changes over time, according to city documents.
The preliminary study found the water elevations would be high enough for the intake system to work, said Andrew Waratuke, principal research engineer with the U of I. A “saddle” north of the dam, a kind of natural dam, would help maintain the water elevation, he said.
A potential problem, however, is the Leo Nelson Riverside Water Plant’s intake system could become isolated from the rest of the river during low flow conditions at “the narrows,” Waratuke said. The “narrows” is where the river channel gets smaller; it’s located near the intake system.
Sediment could create a levy effect blocking the intake from the river, he said.
That potential problem could be addressed by adding six dikes to the area, engineers said. The embankments would be underwater and would not affect recreation on the river, they said.
Researchers will also expand the study area north to incorporate the effects of the Carpentersville dam removal last year. It may help provide some data about how sediment impacted the area, officials said.
In Carpentersville, the river was so low after the dam was taken out that some water and sewer lines were exposed. The village of Carpentersville temporarily covered the lines but needs a long-term solution that could cost millions to fix.
The new river study should be completed by next year, officials said.
As for the Army Corps’ recommendation on the dam removal, Water Director Nora Bertram said the timetable has changed. More evaluation is being done, and the agency wants to meet with municipalities before completing its amended report, she said.
“I’m thinking the schedule is probably going to be pushed out a little bit,” Bertram said.
The agency plans to ask communities in January for non-binding letters of support for dam removal, she said. The letters would only indicate interest and would not commit any municipality to having their dam taken out.
At this point, they think their new recommended plan will be ready in spring 2026 and approval completed by fall 2026, Bertram said. The Army Corps has said it will cover the cost of dam removal for communities that agree to it.
“We need to make our decision if we want to continue with them to remove the Kimball Street dam in January 2027,” she said.
Gloria Casas is a freelance reporter for The Courier-News.
