Kane County staff detail sweeping stormwater ordinance updates on solar, wetlands and modeling; public review planned

Kane County staff told the county’s Stormwater Committee that they plan a set of proposed clarifications and additions to the countywide stormwater ordinance, including tighter technical guidance for solar arrays, a standard for modeling and changes to how wetland mitigation fees are set.

Jody Wallnick, director of environmental water resources for Kane County, said the ordinance dates to 2001 and was reorganized in 2019 to be more user friendly. “The 2019 revisions really reorganized the ordinance,” Wallnick said, and they included work with the Farm Bureau and other stakeholders to balance urban and rural requirements.

Why it matters: the changes would affect municipal permitting, developer costs and how communities evaluate flood risk and wetland impacts. Staff said the goal is clearer, more implementable standards while preserving local flexibility.

Staff summarized an audit of ordinance implementation across the county. Wallnick said all 25 certified communities responded to the audit: in 2024 the county recorded about 160 stormwater permits and 49 Category‑1 BMPs (infiltration trenches/rain gardens). Four communities reported coordinating downstream reviews with adjacent jurisdictions, and staff recorded one fee‑in‑lieu collection for wetland mitigation in 2024. “The total stormwater permits issued… is a 160,” Wallnick said.

Solar and BMPs: Anne Wilford, the county’s stormwater manager, described two linked proposals. First, maintain the 2019 best‑management‑practice (BMP) trigger requiring an infiltration or comparable BMP once new impervious area reaches 5,000 square feet. Second, add a definition for ground‑mounted solar as a form of “disconnected impervious” and require either row spacing/vegetation that demonstrably achieves an inch of infiltration between rows or an engineered BMP. “We would like to see an inch of water… infiltrate into the ground between each row of the panels,” Wilford said. Committee members asked about vegetation establishment and enforcement; staff said inspections are required and a notice of violation would be issued if sites erode or vegetation fails to meet permit conditions.

Modeling and rainfall data: Rob Linke, project engineer and wetland specialist, recommended removing obsolete modeling packages from the ordinance and referencing HEC‑RAS (including 2‑D 'rain on mesh' capability) for floodplain analysis, aligning county practice with FEMA. On rainfall data, staff proposed requiring Illinois State Water Survey Bulletin 75 for design while allowing communities to request Bulletin 76 scenario runs as an optional "what‑if" analysis to evaluate climate‑projection scenarios. Staff said the change to Bulletin 75 increases the local design storm by about one inch compared with older guidance.

Wetlands and mitigation: staff reported that mitigation‑bank credits are often unavailable and proposed a process to query local mitigation banks annually and publish a fee‑in‑lieu rate on January 1 so developers know the rate when credits are unavailable. In 2024 Kane County processed three wetland mitigation permits totaling roughly 0.82 acres (two mitigated with bank credits; one via a $32,000 fee‑in‑lieu), and staff reported about $2.2 million collected to date in wetland fee‑in‑lieu dollars and roughly $2.3 million spent on wetland creation projects.

Buffer and impact clarifications: staff proposed a mitigation pathway when buffers cannot be met — either a partial fee‑in‑lieu (one‑quarter of the wetland mitigation fee per acre) or enhancement of adjacent wetlands at a 1:1 ratio at the director’s discretion — and to expand the wetland‑impact definition to include non‑stormwater illicit discharges (for example, chemical spills) and the remediation disturbance they cause. Staff also clarified that low‑quality wetlands (floristic quality index, FQI, under 7) converted to a natural stormwater basin within the footprint may be treated differently for mitigation, but total impacts are summed and mitigation is required once impacts exceed 0.1 acres.

Process and next steps: staff said they will prepare a memo and marked‑up ordinance language, circulate it to certified communities, local engineers, FEMA and the Illinois Department of Natural Resources for a 45‑day review, and then host a public hearing before this committee. If approved by the committee, the ordinance language would be forwarded to the county board for adoption. Wallnick estimated a roughly three‑to‑four‑month schedule and said a public hearing could occur early to mid‑summer.

The committee did not vote on the ordinance language at the meeting; staff will return with the public‑comment results and any revised language at a later meeting.