True Left

America’s obsession with road salt is hurting freshwater ecosystems — and our drinking water
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Hintz’s findings reveal that human-induced salinization causes substantial die-off of zooplankton populations in lakes across North America. Zooplankton are tiny microorganisms that feed on bacteria and algae. Creatures higher up in the aquatic ecosystem food chains in turn eat the zooplankton.

Mortality increased even in lakes where chloride levels — indicators of salinization — are at or below acceptable thresholds according to U.S. and Canadian laws. Chloride is often combined with sodium to create the salt (NaCl) often used in deicing salts, so it is a good marker for determining how much salt is in water.

In more than 70 percent of the lake sites studied where significant zooplankton mortality occurred, chloride levels did not exceed the legal limit.
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Saltier lakes could potentially mean bad news for humans, too. We depend on freshwater ecosystems for our drinking water. The Great Lakes on the Canada-U.S. border provide drinking water for more than 40 million Americans.

“Once salts get into our freshwater supplies, it is difficult or in some cases impossible to get salt out, and high salt concentrations can persist for decades,” Hintz says.