Reduce the Chloride: The Winter Salt Problem Nobody Talks About

Unlike sediment, which can settle out in grit chambers and wetlands, or phosphorus, which alum treatments can bind, dissolved chloride passes straight through the filters and restored shorelines that protect the lakes. Once it reaches the water it accumulates, and each winter adds more. The Minnesota Pollution Control Agency reports that chloride levels in Twin Cities lakes and streams have been climbing for years and that there is no practical way to remove it after it dissolves, which makes prevention the only real strategy.

The Minneapolis Park & Recreation Board samples chloride along with phosphorus, nitrogen and chlorophyll-a as part of its routine lake monitoring, and works with certified Smart Salting applicators to cut the amount spread on park property. At high enough concentrations, chloride harms the aquatic insects and fish the lakes support.

What makes salt unusual among lake pollutants is that the most effective response sits at the front step rather than with any agency. The MPCA's Smart Salting program trains plow drivers and private contractors to use far less salt without sacrificing winter safety, noting that just one teaspoon of salt permanently pollutes five gallons of water. The agency's guidance to residents is the same: shovel early, scatter salt sparingly and only where needed, and use sand instead when temperatures drop below 15 degrees, since most de-icers stop working in that range. For the neighborhoods ringing Lake of the Isles and Bde Maka Ska, a lighter hand with the salt bag is a rare lake problem a homeowner can act on directly.