Engineers present stormwater master plan that prioritizes Isaac Walton Lake restoration and detention sites

Consulting engineers from Bolton & Mink presented the West Burlington stormwater infrastructure master plan, describing a model of the city’s watersheds, identified deficiencies and recommended prioritized projects to reduce flooding.

Ryan Bengur, water‑resources engineer leading the study, told the council the city has two primary watersheds and that one route drains through Lur’s Park under the concrete plant to Isaac Walton Lake. The plan identified undersized storm sewers, inadequate outlets and neighborhoods lacking branch sewers. Engineers highlighted seven larger capital opportunities including channel regrading in Lur’s Park to lower flow lines and multiple detention sites (examples cited: ~6 acre‑feet at Community Park, ~8.8 acre‑feet at the ABB/old GE area, ~10 acre‑feet at Pennington/Roar) that could reduce downstream flood peaks.

A central recommendation was restoration/dredging of Isaac Walton Lake and repair of a silted culvert under the railroad; the engineers said lowering lake elevations 3–5 feet and repairing the culvert would unlock benefits for other downstream projects. The consultants noted the culvert condition is complex because of railroad ownership and access constraints; they also described drainage‑district and other legal mechanisms that can be used to compel downstream improvements if necessary.

Engineers recommended pursuing FEMA hazard‑mitigation grant funding for lake design and dredging and moving forward with shovel‑ready detention projects that are relatively cost‑effective and eligible for state cost‑share when combined with public‑benefit elements (nutrient reduction, park improvements). They cautioned that upsizing storm sewer pipes and accompanying street and utility work substantially increases costs and recommended coordinating sewer upgrades during street projects to minimize incremental expense.

Council members asked whether proposed detention sites account for the new workforce‑housing development discussed earlier; staff and engineers said the study predated that project but noted preliminary conversations with developers and that drainage solutions can be adjusted as development plans are finalized.

The presentation concluded with next steps: coordinate with Des Moines County Conservation on lake work, develop FEMA grant applications and advance cost‑benefit analyses to qualify for funding, and move forward with detention projects and targeted storm‑sewer upgrades as funding and permitting allow.