Road salt being used on Madison’s west side has contaminated a well with sodium and chloride, and may require a very expensive solution, according to the Madison Water Utility.
The utility said the amount of chloride, which causes water to have a “salty” taste, has been measured at Well 14 at 125 mg/L, or 50 percent of the EPA’s secondary maximum contaminant level for the chemical.
In addition, the amount of sodium levels at Well 14 are around 45 mg/L, which is higher than the recommended limit for people on salt-restricted diets.
Water utility officials said there have been dramatic increases in the amount of sodium and chloride at the well since 2000. Chloride levels have doubled since then.
Officials said road salt is likely to blame for the rising levels. About 140 tons of road salt is used on University Avenue between Segoe Road and Allen Boulevard.
However, officials from the Wisconsin Geological Survey said salt spread in the area on parking lots, sidewalks and driveways on the west side also plays a role.
"We always monitor salt levels in all our wells. We have one well that is higher than the rest," Tom Heikkinen, Madison Water Utility manager, said of Well 14.
Officials said even if salt use was stopped across the west side of Madison, there is already a large amount of sodium chloride in the ground around University Avenue that would continue to make levels rise.
"It's totally human induced we have an expectation of safe pavement during the winter time and that's great for safety, but we have to figure out how we're going to reduce our use of salt for the sake of our drinking water and our lakes and streams," Heikkinen said.
The utility will start analyzing the area around the well to see which areas below ground are causing the most sodium chloride to get into the water pumped from the well. Once that is determined, the utility will look at all options, from rebuilding part of the well to bring water from deeper in the aquifer to adding desalination treatment to abandoning the well completely.