An estimated 352,000 pounds of lead washed into Lake Coeur d’Alene on Jan. 18 after flooding related to a rain-on-snow event. That’s the weight equivalent of 70 Dodge Ram 1500 pickups – and the highest volume of lead recorded in a 24-hour period since major flooding in February 1996.
Greg Clark, a U.S. Geological Survey hydrologist, attributed high lead concentrations to a rapid rise in the Coeur d’Alene River caused by pounding rains and melting snow. At Harrison, where the river empties into Lake Coeur d’Alene, the Jan. 18 flows averaged 19,000 cubic feet per second.
“We haven’t seen those kinds of flows in quite a while,” said Clark, associate director of the Idaho Water Science Center in Boise. “We end up with a lot of metals – lead in particular – transported to the lake during those types of events.”
The lead is the legacy of 140 years of hard-rock mining in the Coeur d’Alene River’s headwaters. Government officials said the January data demonstrates the complexity of mine Superfund cleanup.
“There’s so much lead in that upper basin,” said Ed Moreen, a program manager for the U.S. Environmental Protection Agency. “It’s going to continue to get picked up and redistributed into Lake Coeur d’Alene until we can do something about it.” (read more)
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