For decades, state and local officials have looked the other way when it comes to addressing water quality issues threatening Lake Coeur d’Alene. Hopefully, with help from the National Academy of Sciences and $2 million in state funding, Lake Coeur d’Alene might be at the beginning of its road to recovery.

Millions of tons of toxic metals are trapped in the sediment at the bottom of Lake Coeur d’Alene due to legacy mining operations in the Silver Valley. The water chemistry of the lake is able to hold the metals in place within the sediments, keeping the toxic metals from doing any damage. If, however, the water chemistry were to change, the metals could be released from the sediment into the lake water. 

Recently, there has been an increase in the amount of phosphorus and nitrogen pollution entering the lake from failing septic systems and land development. If concentrations of phosphorus and nitrogen in Lake Coeur d’Alene get too high, the water chemistry can change and the toxic metals trapped in the sediment at the bottom of the lake could be mobilized into the water through a complex chemical process. 

The Coeur d’Alene Tribe and the Idaho Department of Environmental Quality drafted a Lake Management Plan to reduce new sources of phosphorus and nitrogen when there were first signs that these pollutants were increasing. That was several years ago. The plan fell short because it was strictly voluntary. In 2019, the Tribe formally withdrew from the plan due to its inability to actually improve water quality. 

With phosphorus and nitrogen levels continuing to rise, DEQ, the Environmental Protection Agency, Kootenai County, and the Coeur d’Alene Tribe have sought assistance from the National Academy of Sciences. They have asked NAS to look at these trends and provide recommendations to address the issue.

Additionally, Idaho Governor Brad Little is proposing $2 million to pay for projects that reduce phosphorus and nitrogen pollution in Lake Coeur d’Alene

With actions like these from local, state, and federal officials, the Idaho Conservation League hopes that kicking the can down the road will finally stop and a clean-up of the iconic northern Idaho lake will happen soon. 


If interested in learning more about the goals of the NAS study on Lake Coeur d’Alene, you can attend one of the upcoming public information sessions found here!