Chloride threatens groundwater

Angie Hong

East Metro Water

Trying to follow a low-sodium diet? Perhaps you should cut back on the amount of water you’re drinking.

A recently published Minnesota Pollution Control Agency report says that one-third of the state’s wells had increased chloride concentrations, and 30 percent of metropolitan area wells had chloride concentrations above the standard set by the U.S. Environmental Protection Agency.

Chloride (salt) is naturally present in Minnesota’s groundwater due to weathering of rocks. It is also getting in through use of road salt, fertilizer and water-softening salt.

Salt has a devastating impact on fish: a teaspoon will contaminate five gallons of water.

Several Twin Cities lakes and streams have unhealthy levels of chloride, and now salt is reaching aquifers.

High chloride concentrations can be toxic to fish and aquatic life in groundwater-fed lakes, streams and wetlands, and makes our drinking water taste bad, too.

Most chloride in our water is a by-product of winter de-icing. We apply salt to roads, parking lots and sidewalks to melt snow and ice faster.

Unlike many pollutants, chloride does not break down in soil or water. Almost all the salt migrates to surface or groundwater resources.

In recent years, the Minnesota Pollution Control Agency has mounted a broad effort to educate state, county and municipal employees, as well as the general public, about the damaging effects of road salt.

MnDOT and many communities have modified their winter maintenance procedures. Hundreds of public works staff from across the state have received training to reduce salt usage by pre-treating roads when storms are forecasted, precisely measuring the application rate and targeting salt to areas that need it most — intersections, hills and curves. Some communities have retrofitted their fleets with GPS and pavement temperature sensors to help road crews target de-
icing efforts.

Yet our lakes, streams and groundwater get saltier by the year.

Two of the biggest challenges in reducing salt use include working with commercial properties and private contractors, and educating the general public about why they’re seeing less salt on many streets and highways.

Retailers who are afraid of getting stung by lawsuits often apply way more salt than is needed to make their parking lots safe, and many private contractors are paid per pound of salt applied, creating a disincentive to apply less.

Meanwhile, local municipalities are sensitive to complaints from residents that roads are slippery and unsafe.

It’s hard to care about water resources during the winter when roads are covered in snow and it’s a challenge getting to work. At the same time, however, fishing is a $1.58 billion industry in Minnesota, and 75 percent of Minnesotans rely on groundwater for drinking.

Cities that change their practices usually see cost savings. Citizens can do their part by driving more slowly and wearing appropriate footwear in order to reduce the need for salt.

The message is simple. Salt is bad for people and fish. Take it easy this winter and wear some boots so we don’t make our water any saltier.