Stormwater retention ponds may not protect surface waters from road salt contamination

Stormwater retention ponds may not protect surface waters from road salt contamination.
Stormwater management practices are designed to intercept water runoff from roads and parking lots before pollutants reach surface waters.
Detaining runoff in retention ponds can reduce flooding, increase the amount of water that is absorbed into the ground, and allow pollutants to bind to sediments in the ponds or be absorbed by algae and plants instead of traveling to streams and wetlands where they may harm wildlife and human health.
The research team recently completed a study, published in Environmental Science and Technology, to determine how well current stormwater management practices mitigate the effects of road salts and how those salts might be impacting both the surface waters in streams and ponds, and the groundwater that many citizens using well systems rely on daily.
If the stormwater ponds were working effectively, Snodgrass explained, he and his team could test the groundwater between the ponds and streams and expect to find very little sodium chloride because it would have been retained in the ponds.
The researchers discovered that routing runoff contaminated with road salts to stormwater ponds actually resulted in plumes of highly contaminated groundwater moving from the ponds to streams.
If salt levels continue to increase in freshwater areas, many fish and amphibians will stop breeding and eventually die because their bodies cannot adjust to the change.
"Some counties are already reimbursing people for the costs associated with replacing contaminated water wells," he added.
Snodgrass and his team plan to continue researching how road salts and other chemicals affect wildlife and the environment, while other researchers are exploring the effectiveness of alternatives to road salts and their potential effects on the environment and human health.
"It’s a balance sheet we’re looking at between economics and the environment and human health," Snodgrass said.

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