La Crosse plans multi-year well overhauls following disinfection byproduct spike

La Crosse plans multi-year well overhauls following disinfection byproduct spikeElevated haloacetic acid levels have exposed severe aging in the Wisconsin city's groundwater infrastructure, prompting planned replacements for eight well casings that have exceeded their 50-year design life.

Recent water samples yielded HAA5 levels up to 151 ppm, well above the 60 ppm maximum contaminant level, caused by treatment chemicals interacting with natural biofilm.

The utility will launch a multi-year capital project to replace gravel packs and casings for eight of its ten wells, four of which are over 71 years old.

Chemical rehabilitation of Well 13 is slated for later this year, alongside exploratory test drilling for a new Well 27 this fall.

The city is proactively removing 200 lead goosenecks annually, anticipating that federal regulators may accelerate compliance timelines due to the city's reliance on natural mineral corrosion control.

A recent spike in disinfection byproducts has prompted the City of La Crosse Water Utility to launch a multi-year capital project to overhaul its aging groundwater wells. During an August 10, 2026, Board of Public Works meeting, a utility representative detailed how elevated haloacetic acid (HAA5) levels exposed critical vulnerabilities in the city's well casings and gravel packs. Recent water samples in 2025 yielded HAA5 levels of 120 and 151 parts per million (ppm), significantly exceeding the regulatory maximum contaminant level of 60 ppm. The utility noted that a shift in well utilization altered the system's equilibrium, causing treatment chemicals to interact with natural biofilm growth in the wells and mains. While immediate rebalancing has stabilized the system, the event revealed the need for structural restoration. Eight of the city's ten well casings have exceeded the industry standard lifespan of 50 years, with four surpassing 71 years of age. In response, the utility is preparing a multi-year capital project to replace the gravel packs and well casings for the eight identified wells to stabilize the subsurface environment. In the near term, the city has procured three contractor bids to chemically rehabilitate Well 13 later this year. An engineering consultant has developed a specific chemical targeting program to aggressively treat the well's unstable biofilm. The rehabilitation, which will also include rebuilding the well's motor, is expected to take three to four weeks depending on lead times. Additionally, exploratory test drilling for a new production well, Well 27, is scheduled for the fall of 2026 at a site near Emerson Elementary, pending final approval from the Department of Natural Resources. To further improve water quality, the utility has reinstated a legacy daytime flushing program utilizing turbidity meters. The spring 2026 event required a 10-person crew to flush 185.5 million gallons of water across 1,995 hydrants. The HAA5 spike also required careful monitoring of the city's lead and copper compliance. La Crosse relies on "platinorite"—a natural mineral scale—rather than chemical additives for corrosion control. Utility staff confirmed that despite the disinfection byproduct issues, recent monitoring showed the platinorite scale remains stable, with the second round of sampling returning 35 zero-detect results so far. The city is currently advancing a lead gooseneck replacement program launched in 2024, aiming to remove 200 of its roughly 1,700 remaining lead goosenecks annually. While the federal deadline for complete removal is 2037, utility staff noted that the EPA could require La Crosse to accelerate its timeline due to its reliance on natural corrosion control. Following the elimination of the lead goosenecks, the utility plans to target 6,303 service lines classified as Galvanized Requiring Replacement (GRR).