Leftover Road Salt Affecting Water Sources

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COLUMBIA - The harsh weather winter caused crews to spread roads and sidewalks with rock salt. Tuesday, researchers said the large amount of salt on the roads may be starting to affect human health.

Since late November 2013, the chloride levels have been spiked in Hinkson Creek due to the addition of salt on the roadways for safety purposes. EPA (Environmental Protection Agency) standards for drinking water is about 250 milligrams of chloride per liter. The receiving waters in the Columbia area have consistently had higher chloride levels since November 2013.

According to Jason Hubbart, Professor of Hydrology and Water Equality in the School of Natural Resources and Director of the Water Center for the MU College of Agriculture, Food, and Natural Resources, experts used to think of chloride as something that would easily filter in and out of water systems quickly, but recent studies have shown it can take months for chloride to wash out.

"This is particularly important for watersheds like Hinkson Creek where some of the current management strategies are to reduce the amount of runoff," Hubbart said.

The highest concentration of chloride levels recede during low flow so "dilution is the solution to pollution in this case because that increased flow helps to reduce the toxic levels," he said.

Hubbart said the spiked levels of chloride are common for the area in the winter season. The MU School of Natural Resources, Boone County and the City of Columbia have been working on improving policies and practices in Hinkson Creek.

"The issue is we need to find alternatives to road salts because we're talking about human health here and human safety. Human health goes with chloride in the water and human safety with 'do I go slip-sliding from the road," Hubbart said.

The goal, he said, is to restore Hinkson Creek to pre-developmental levels of creek life. Very high chloride levels affect living population for up to a year.