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Currents of Change

Chloride in Lakes

Road Salt PilesWintertime road maintenance with salt and similar materials can harm freshwater habitat. A study of the Scituate Reservoir watershed by the U.S. Geological Survey (USGS) evaluated sources of sodium and chloride to the reservoir from 1999 to 2000. Sodium concentrations in the reservoir have been increasing, despite the use of reduced-sodium deicing materials on state roads in the watershed. The study concluded that deicing of state and local roads was the major source of sodium and chloride in the drainage basin, accounting for 67 percent of the 1,000 tons of sodium and 90 percent of the 2,300 tons of chloride introduced into the basin.

Sewer grate being corroded by road salt

University of Rhode Island Watershed Watch volunteers have monitored chloride in Rhode Island lakes since 1988. None of the results exceed state criteria for aquatic life (chloride concentrations of 860 milligrams per liter (mg/l) (acute effects), 230 mg/l (chronic)) but many locations show a trend of increasing concentration over time.

Road salt can harm lakes and other aquatic ecosystems by increasing the salinity of fresh waters. It also has corrosive effects on cars, sewer grates and roads. Many states are looking toward alternative methods of deicing that are
less corrosive and damaging to the environment.

Graph of chloride in lakes over time


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Water Quality Evaluation

Chloride in Lakes


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