Shrinking snow piles are one of the first signs that spring is on the way. Over the long winter, these piles accumulate pollutants like road salt, sand, automotive oils, car exhaust, litter and pet waste. When spring thaw occurs, these contaminants can deteriorate water quality, impacting drinking water supplies, fisheries and wildlife.
Nonpoint source pollution, which includes snowmelt runoff, is the leading cause of water pollution in the country, according to the Environmental Protection Agency (EPA). Additional pollutants are picked up when snowmelt moves across land. Each substance can have harmful impacts on waterbodies.
Road salt
Salts like sodium chloride are used to de-ice roads, sidewalks and driveways during winter weather events. Road salts contaminate drinking water supplies, causing health concerns for people with high blood pressure. Additionally, high chloride levels are toxic for many types of wildlife. NEIWPCC maintains a Chloride Resources Clearinghouse to provide innovative and alternative chloride reduction strategies.
Automotive oils
Oil and automobile fluids accumulate on roadways and are plowed into snow piles. Eventually, when snowmelt occurs, these fluids may make their way into the water. They contain concentrations of heavy metal toxins that are harmful to human health, plants and wildlife. According to the EPA, one gallon of oil has the potential to contaminate up to 1 million gallons of freshwater.
Sand
Snow removal personnel often use sand to create a layer of traction on slippery roads, while waiting for road salts to take effect. Sand absorbs oils and other toxins found on roadways. When run off occurs, sand clogs catch basins and drainage pipes, making them less effective and in need of maintenance. Additionally, sand clouds the water and contributes to erosion.
Litter
Snow piles accumulate trash in several ways, including collection by plows during winter weather events; garbage blowing from trash receptacles during storms; and litter thrown from cars or pedestrians. Litter that gathers in snow storage locations should be promptly cleaned up after thawing occurs, to avoid it entering a waterway.
Pet waste
Pet waste also winds up in snow piles through runoff, plowing and improper disposal. As it decays, it lowers the oxygen level in the water and releases ammonia, which can kill fish. Pet waste adds nutrients to the water that encourage weed and algae growth. Additionally, it may contain harmful bacteria and parasites that make humans and animals sick.
Storing Snow to Reduce Contamination
Taking action before the snow begins falling can mitigate some of the harm caused by pollutants in snowmelt. Each state in the Northeast has regulations and guidance on how to properly store snow in a way that protects water supplies and waterbodies and minimizes threats to wetland ecosystems.
Snow dumping, which refers to the practice of relocating excess snow using front loaders and trucks, should occur in upland areas near flowing surface waters, which allow pollutants to dissipate prior to entering a waterway. Municipalities and businesses should estimate the amount of snow they anticipate receiving and identify proper storage locations in their community.
Snow storage should be avoided in areas that are considered ecologically vulnerable, such as wetlands, or in locations that contain public or private water supply wells, where groundwater contamination could occur. Additionally, maintaining a distance from high water marks and selecting vegetated areas can prevent and reduce flooding once thawing occurs.
Per regulations established in the federal Clean Water Act and Wetlands Protection Act, it is illegal to dispose of snow directly into the ocean or other surface waters. Temporary permits can be issued by each state, however, in the case of a snow emergency — such as the one that occurred in Massachusetts during 2015 — if snow cannot be safely stored otherwise.
In densely populated urban areas, snow storage is often a problem. Due to narrow streets, heavy traffic and limited open space, cities experience increased demand for snow removal and fewer storage spaces. As a result, snow is often piled on impervious surfaces like roads, sidewalks and parking lots. Unlike vegetated areas, which can filter out pollutants, snowmelt on impervious surfaces accumulates additional contaminants before reaching a storm drain or waterbody.
Cities can also experience flooding caused by snowmelt when the land surface is covered by cement or asphalt that cannot absorb water. This occurs when snowmelt happens rapidly or is combined with spring rains. For this reason, urban municipalities should take extra precautions to ensure that snow piles are kept far enough away from waterbodies prone to flooding.