Committee leans toward removing Fox River dam with culvert to preserve mill race flow

The Committee of the Whole reviewed an IDNR study of possible changes to the Fox River dam and discussed next steps, including a public input meeting coordinated with the Illinois Department of Natural Resources and the Fox Valley Park District.

Staff told the committee the IDNR favors full dam removal to restore river ecology and reduce safety risks, but the village has asked the agency to analyze a compromise: alternative six, which removes the dam and installs a culvert to maintain reduced flow into the mill race. "The Illinois Department of Natural Resources' goal is full dam removal because for them that creates ecosystem balance," staff said, but added that option six would preserve water in the mill race albeit at lower depth and flow.

Technical modeling presented at the meeting showed current depths of about 7 feet at a measurement point behind the dam; after removal, depths at that point could drop to something under two feet in normal conditions and to about half a foot in low‑water periods. The culvert option preserves some flow to the mill race but reduces flows — staff estimated that in low flow the mill race might receive 30–40% of current low‑flow volumes and median flows might drop roughly 20 percent.

Cost estimates shown by staff put full removal at roughly $2.6 million (state funding would cover most costs) and the culvert option about $400,000–$425,000 more; local costs would likely be limited to easements or small property acquisition (staff estimated local share near $33,000). Staff also said that a local agreement with the Fox Valley Park District and an intergovernmental agreement with the state would be required to advance a culvert option and preserve the mill race.

Trustees expressed support for alternative six — "keep the culvert, remove the dam" — citing drowning hazards below the dam and the Carpentersville example where removal produced visible shoreline and new vegetation. Staff warned the board that the state retains ownership of the dam and could remove it on its own timetable; "the state could always choose to remove the dam on their own should they want to," staff said, underscoring the need to engage the Park District and clarify local responsibilities if the village wants to preserve the mill race.

What’s next: staff said they would contact the Fox Valley Park District, schedule a public input meeting with the IDNR if the board wants to continue the study, return results to the committee after public feedback and then, if desired, draft any intergovernmental agreements and engineering tasks necessary for the state to bid construction.