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Madison Water Utility is launching a multi-year study aimed at finding a way to mitigate road salt contamination at municipal Well 14 on University Avenue. Well 14 is a major source of water for Madison’s near west side, pumping more than 750 million gallons into the distribution system every year. Unfortunately, testing has shown dramatic increases of sodium and chloride (the components of salt) in water pumped from the 56 year-old well, particularly since 2000. Chloride levels alone have doubled at the well since that time.
Finding a solution to the issue will be costly and difficult. Madison Water Utility will likely begin by analyzing the well’s bore hole in an effort to see which areas below ground are contributing the most sodium chloride to water pumped from the well. From there, the utility will look at every available option -- from rebuilding part of the well in order to draw water from deeper in the aquifer to on-site desalination treatment to abandoning the well entirely.
While the chemicals that make up salt are not considered a health threat to most people, they do have an impact on water quality. Sodium levels at Well 14 are around 45 mg/L, and should be noted by people under severe, physician-ordered salt restrictions. Chloride, the component of salt that causes the “salty” taste, has been measured at the well at 125 mg/L, or 50 percent of the EPA’s secondary maximum contaminant level (SMCL) for the chemical. According to our current water quality policy, we must launch a remediation study if a contaminant reaches that 50 percent threshold. If current trends continue, Madison Water Utility projects that chloride levels will exceed the SMCL in about 17 years, at which time the water may be difficult to drink because of the salty taste.
Source of the salt
Every winter, about 140 tons of road salt are dumped on the two-mile stretch of University Ave. between Segoe Rd. and Allen Boulevard. However, research from the Wisconsin Geological Survey indicates that salt spread in the immediate area around Well 14 is only part of the problem. Salt put on roads, parking lots, sidewalks and driveways on the west side of Madison stretching all the way to West Towne Mall generally washes toward the Spring Harbor neighborhood and Well 14. Even if salt use was discontinued across that entire area of Madison tomorrow, there is already a large enough reservoir of sodium chloride in the ground around University Ave. that levels at Well 14 would likely continue to rise.
Road salt found in other wells
In less than 60 years, Well 14 has gone from a new well with high-quality water to one with a critical road salt contamination issue. As we look across the city, Madison Water Utility is concerned about what the next six decades could bring for other major wells. Well 11 on Dempsey Rd., Well 6 on University Ave., and Well 16 on Mineral Point Rd. all show increasing levels of sodium and chloride, albeit at much lower levels than Well 14 (see attachment). It’s possible that if nothing is done to decrease road salt use across our area, we will be looking at costly chloride mitigation efforts at some of those of wells and others in the coming decades.
“Rising levels of chloride in our groundwater and lakes should be a cause of concern to all of us,” says Madison Water Utility general manager Tom Heikkinen. “As a region, we are on an unsustainable path with respect to wintertime salt use and we need to figure out how to solve this problem now for the sake of future generations.”
Becoming a “Salt Wise” community
Madison Water Utility is a proud member of the Wisconsin Salt Wise Partnership, a coalition of city and county agencies, educators and environmental groups working to get the word out about responsible salt use. Sodium chloride isn’t just a groundwater issue. It’s accumulating in all bodies of water in the Madison metropolitan area, including Lake Monona, Lake Mendota, Lake Wingra, Starkweather Creek, Dunn’s Marsh, Cherokee Marsh, and Willow Creek. But even small changes can make a real difference in the amount of salt we use as a community and the impact we have on our environment. The attached Wisconsin Salt Wise press kit contains a list of experts who can provide more insight into the environmental damage caused by salt and what we as a community can do to help stop it.


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