A study found high lead levels linger in parts of the La Crosse River Marsh, more than a half-century after a gun club stopped firing over the wetlands from Myrick Park.
While the contamination isn’t enough to warrant a cleanup or warnings about eating fish from the marsh, signs should be put up educating the public about the lead and advising they perhaps avoid fishing or walking out into certain sections where the concentrations are highest.
One particular lead hotspot is just off a culvert on the marsh “rabbit trail” that has been a common fishing site, said Colin Belby, an associate professor at the University of Wisconsin-La Crosse who helped launch the marsh lead study in 2010.
The study, funded with an U.S. Environmental Protection Agency grant and support from UW-L and the state Department of Natural Resources, focused on the waters just east and west of the trail from where it starts in Myrick Park to the split to the observation area and the pathway continuing north and west through the marsh. Surface soil samples were taken at almost 400 sites in those areas, along with 33 core samples.
The La Crosse Gun Club for almost 35 years did trap shooting over those pools before ending the practice in 1963. The research team found some core samples showed 50,000 pellets per square meter, still imbedded in the underwater soil.
The wet soils on the west sides of the trail had surface lead levels as high as 26,700 milligrams per kilogram, “well beyond” what qualifies as contaminated, Belby said.
Yet the levels did not rise to “impaired waterway” status that might have triggered dredging or other costly measures to remove or treat the contaminated soil, Belby said. A cleanup would conceivably cause more harm than good, he added, as the site likely would have to be drained to remove the lead-laden marsh sediment while trying to contain runoff; the contaminated soil would have to be disposed of as well.
The lead for now has shown little sign of spreading into the rest of the marsh. Tests on aquatic insects and vegetation did have higher but not alarming levels of lead, he said. More importantly, tests on the trail berm, where the public would be more likely to come in contact, came out relatively clean, Belby said.
He suggested continued monitoring and perhaps checking for effects on waterfowl and other birds that feed in the marsh, along with posting the educational signs.
The signs, too, could provide both history and a cautionary note about how actions in the marsh can have repercussions for generations to come.
“We all know,” council president Dick Swantz said, “what a precious resource the marsh is.”