Oconomowoc council adopts tighter wellhead protection rules, limits stormwater chemicals

The Oconomowoc Common Council on Jan. 25 adopted ordinance 25-01074 to revise the city’s wellhead protection overlay area, adding new inventory, spill-containment and emergency-response requirements for hazardous chemicals and restricting chemical treatment of stormwater ponds to NSF 60–type products.

City staff described the changes as targeted protections for shallower, more transmissive aquifers that feed recently developed municipal wells. “The purpose, the goal of a wellhead protection program is to identify, manage and protect the land areas that contribute groundwater to our drinking wells,” said Scott Osborne, a city staff member involved in water-system planning.

The ordinance language, introduced at a public hearing Jan. 25 after a plan-commission recommendation, requires developers and site operators within defined wellhead protection areas to submit hazardous-chemical inventories, spill-containment measures and emergency-response plans and to secure review by the planning and utility departments before using approved chemical products on ponds or other on-site stormwater features. Staff told the council the rule will apply differently across wells: some protection areas are defined by a 1,200-foot radius while others use a time-of-travel method; staff noted the larger, older well areas previously protected by an earlier ordinance and said the new text adds safeguards for newer, shallow sand-and-gravel wells.

The wellhead changes were recommended by the plan commission on Jan. 8 and were presented to the council with staff summaries of the city’s water system and the ordinance’s intent. The council voted unanimously on a motion to adopt the ordinance and to waive further reading.

During the public hearing, residents asked how the limits would affect pond maintenance. Doug Kaiser, who lives near Pabst Farms and serves as secretary for his condominium association, said he was concerned that banning or limiting chemical treatments would leave neighborhood ponds choked with weeds. “If this, in fact, is going to change that to where we’re gonna have a pond that is just weeds going forward, I will tell you that a number of us will be very disappointed,” Kaiser said.

Staff responded that the ordinance allows use only of NSF-approved products for certain pond treatments and that staff and the city’s contracted pond companies are still searching for approved herbicide options to control cattails and other emergent plants without risking groundwater. City staff said mechanical removal and cutting are possible alternatives but are more labor-intensive and costly.

Council members pressed staff on enforcement and cross‑jurisdictional issues where wellhead areas extend outside city limits; staff said the city will rely on intergovernmental cooperation, public education and existing border agreements to encourage consistent protection in adjacent areas.

The ordinance text (25-01074) and staff presentation say the changes are intended to strengthen protection of the municipal water supply by adding inventories, containment and approved-product restrictions; staff said the plan commission gave a positive recommendation on Jan. 8. The council’s unanimous vote on Jan. 25 adopted the ordinance and waived further reading, sending the new requirements into effect as provided in the ordinance.

Councilors and staff said they will continue outreach to neighborhood associations, the Pabst Farms stormwater district and other stakeholders to explain the new requirements and to seek workable approaches for pond maintenance that protect drinking water.

Copies of the ordinance and the staff report are in the council packet; the plan commission recommendation is on file with city planning.