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Water quality in CDA Lake has improved in 30 years, but report warns recovery is far from over

Courtesy of Idaho State Parks

A new analysis says water quality in Coeur d’Alene Lake has improved over the last three decades. But the researchers who conducted the analysis have some worries about the future.

A century of metals mining in the watershed that feeds into Coeur d’Alene Lake exacted a massive price on the reservoir. Its waters were laden with cadmium, lead, zinc and arsenic. But changes in mining practices and an intensive environmental cleanup helped give the lake a new lease on life.

An analysis from the National Academies of Science, Engineering and Medicine studied water quality in the lake over a 30-year period. Researchers found the proportion of those toxic metals has fallen. Sam Luoma, one of the people who worked on the analysis, said that’s an impressive achievement.

But Luoma also cautioned the findings also hint at how climate change may shape the lake.

“Air temperatures are warming, by as much as 2.5 to 3 degrees Centigrade, it’s projected, by 2050,” Luoma said. “Surface water temperatures are following this, and are increasing. And there has been a decrease in snow-water equivalent in the past thirty years associated with these increasing temperatures. That could all affect inputs of metals and nutrients to the lake.”

Changes to the lake’s environment could also release some of the dangerous metals from lake-bottom sediments back into the water. The report’s authors say even after thirty years, Coeur d’Alene Lake’s revival hasn’t reached its apex; rather, they say it’s just beginning.

“There’s still a long way to go in terms of a full recovery of the lake,” Luoma said. “This is a problem that took a century to develop. It’s a complicated problem. And it will take time to clean it up.”

Brandon Hollingsworth is your All Things Considered host. He has served public radio audiences for nearly twenty years, primarily in reporting, hosting and interviewing. His previous ports-of-call were WUOT-FM in Knoxville, Tennessee, and Alabama Public Radio. His work has been heard nationally on Morning Edition, All Things Considered, Here and Now and NPR’s top-of-the-hour newscasts.