Trying to follow a low-sodium diet? Perhaps you should cut back on the amount of water you’re drinking. The Minnesota Pollution Control Agency recently published a report, The Condition of Minnesota’s Groundwater, 2007-2011, and readers will be shocked to learn that one-third of wells across the state have increased in chloride concentrations and 30% of wells in the Twin Cities Metropolitan Area had chloride concentrations greater than the chronic water-quality standard set by the US Environmental Protection Agency. Will our state’s groundwater reserves become the next Salton Sea?
Chloride (salt) is naturally present in Minnesota’s groundwater due to weathering of rocks. However, it is also getting into the groundwater through use of road salt, as well as fertilizer and water softening salt. Chloride has a devastating impact on fish (only one teaspoon of salt is enough to contaminate five gallons of water) and water monitoring has already found several lakes and streams in the Twin Cities area with unhealthy levels of chloride. Now it appears that this salt is reaching groundwater aquifers as well. 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.
The majority of chloride in our water is a byproduct of winter de-icing. We apply salt to roads, parking lots and sidewalks to help the snow and ice melt faster. Unlike many pollutants, however, chloride does not break down in soil or water, meaning almost all of this salt eventually migrates to surface or groundwater resources.
In recent years, the Minnesota Pollution Control Agency has mounted a state-wide effort to educate state, county and municipal employees, as well as the general public, about the damaging effects of road salt. The Minnesota Department of Transportation has modified winter maintenance procedures and many metro area communities have as well. MDOT and Fortin Consulting have provided training for hundreds of public works staff from across the state on how to reduce salt usage by pre-treating roads when storms are forecasted, precisely measuring the rate of salt and chemical application, and targeting salt to the areas that need it the most – intersections, hills and curves. In addition, some of our local communities have retrofitted their fleets with GPS and pavement temperature sensors to help road crews target deicing efforts.
Unfortunately, however, our lakes, streams and groundwater continue to 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 slip and fall 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 the roads are covered in snow and just getting to work is a challenge. At the same time, however, fishing is a $1.58 billion industry in Minnesota (MN DNR, 2013) and 75% of Minnesotans rely on groundwater for drinking. The Pollution Control Agency and local watershed management organizations continue to offer trainings for public staff and private contractors on ways to reduce salt use during the winter, while still maintaining safe sidewalks, parking lots and roads. Cities that attend these trainings and change their practices usually see cost-savings in addition to protecting their local water resources. Most people don’t use very much salt on their own sidewalks and driveways, but folks at the city and state level hope citizens do their part as well by following some common-sense precautions during the winter, such as driving slower and wearing appropriate foot ware, in order to reduce the need for salt.
The message is simple. Salt is bad for people and fish. Take it easy on the roads this winter and wear some boots so we don’t make our water any saltier.
To learn more about the MPCA Road Salt Education efforts, visit: www.pca.state.mn.us/index.php/about-mpca/mpca-events-and-training/road-salt-education-program.html.