Connecticut often has long, cold, messy winters. During the 2012-2013 season, more than 75 inches of snow fell in the Mansfield area. What’s worse than having to deal with all that snow? Professor Gary Robbins in the Department of Natural Resources and the Environment says it’s the detrimental effect it has on our water.
The Connecticut Department of Transportation (DOT) relies on the use of salt to de-ice the roads to facilitate motor vehicle travel. During the 2010-2011 winter season, the DOT used roughly 2,300 tons of calcium chloride and a staggering 179,000 tons of sodium chloride. That amount of salt is enough to contaminate approximately 175,000,000 gallons of water each year at Connecticut’s maximum permitted contaminant level for chloride of 250 ppm (parts per million).
How does the salt get into our water? Salt is applied to the roads to convert the snow and ice into a liquid form. The majority of this road salt does not soak into the ground but rather flows as storm water discharged into streams. A fraction of the meltwater soaks into the ground and raises the salinity of the groundwater. The amount of saline water that seeps into the ground is determined by several factors, including the permeability of the surrounding soil, nearby vegetation and local topography.
The meltwater affects the aquifers, underground bodies of permeable rock that contain and transmit groundwater. The aquifers are also a main water source for private and public water supplies, thus introducing the high salinity to drinking water. In some places in Connecticut, the salinity level of the local water has already surpassed the state limit.
Researchers like Robbins have been looking into the long-term effects of this continued salt use. Robbins and his colleagues have just concluded a study that examines changes in Connecticut water quality over the last hundred years. The data show a correlation between road salting and an overall increase in groundwater salt concentrations. Since the 1940s, the salinity concentration of groundwater has increased, on average, by a factor of ten, and in some areas of the state over a hundred times. It is believed that this increase is due mostly to the increase in salt usage; there appears to be a strong correlation between the amount of salt used on the roads and the increased concentration in the groundwater.
So what will happen to our water in the future, with continued salt use? Robbins says the issue comes down to balancing salt usage and reducing storm water. Drivers need snow and ice removed from the roads, but using salt may be putting more saline storm water into the ground, affecting drinking water. Additionally, runoff discharged into streams could have detrimental effects on the organisms living in those streams.
“To me, that, plus contaminating water wells, is the real concern of the whole issue,” says Robbins.
By Francesca Crivello