The mere mention of a snowflake in the seven-day forecast has the Washington region scrambling to stockpile food and toilet paper rations from the neighborhood grocery store. Our collective aversion to snow also places great pressure on local departments of transportation to vaporize every snowflake that touches a road surface.

However, the salt that gets spread on our roadways, driveways, parking lots, and sidewalks each winter is putting the quality of our drinking water at risk.

Salt pollution is a national problem

Every winter nationwide we dump more than 20 million tons of sodium chloride (salt) onto our roadways, parking lots, driveways, and sidewalks. Road salts are increasingly contributing to poor water quality in our streams, rivers, and lakes across the country.

According to the US Geological Survey (USGS), de-icing was the primary use of salt (46 percent) in 2008. By comparison, the entire food processing industry, agriculture, and direct consumption was less than 10 percent of the sodium chloride market in that same year.

While the corrosive impacts to road infrastructure and vehicles are well known, we are only recently learning more about the long term impacts to local water quality. Researchers at the University of Minnesota observed rising concentrations of chloride in streams and lakes around the state, and estimate that 70 percent of road salt applied around the Twin Cities remains in the watershed.

Salty water is toxic to humans. The saltier your water is, the more water your kidneys need to filter out the salt. This is why you can't drink seawater: filtering out the salt requires more water than you drink, so your kidney uses water from elsewhere in your body. You get more dehydrated with every drink you take, until you die.

Rising chloride concentrations in streams and lakes harm freshwater aquatic life and also have potential consequences for local drinking water supplies. Recent studies have even shown that exposure to this pollutant can have an effect on circadian rhythms in certain species, which may create a cascading effect on entire ecosystems.

Research is ongoing to determine if our own circadian rhythms could be affected by increased salinity levels in drinking water, which could lead to other health complications such as diabetes, obesity, heart disease, and depression.

Chloride concentrations increasing in our region, too

These water quality trends are also being observed here in the Washington region. Every winter 750,000 tons of road salt is dropped in the Potomac River watershed, which is the primary drinking water source for the region. Researchers have noticed chloride concentrations increasing in area streams and rivers. Fairfax Water and the Potomac River Basin Drinking Water Source Protection Partnership have identified road salt as an emerging concern for drinking water quality in the region.

We walk a fine line balancing public safety, environmental issues, and economic concerns during a snowstorm. Economic analysts estimate winter storms can cost cities and their surrounding suburbs hundreds of millions of dollars per storm when government offices are closed, transportation routes are impacted, and employees have difficulty getting to work.