Community mobilizes to clean up Lake Coeur d'Alene contamination

Two areas in Lake Coeur d’Alene were above lead background levels and 11 were above arsenic background levels across 32 sampled sites in the latest recreational screening of the lake.

Lake Coeur d’Alene sits inside the 1,500-square-mile Bunker Hill / Coeur d’Alene Basin Superfund site, which stretches across northern Idaho and into eastern Washington. The U.S. Environmental Protection Agency added the site to the National Priorities List in 1983 after years of heavy metal contamination and elevated blood lead levels in local children. Mining and milling in the Silver Valley began in the 1880s, and more than 60 million tons of metal-contaminated tailings had been discharged into rivers and waterways from 1880 to 1968. More than 100 million tons of mine waste, including 2.4 billion pounds of lead, were dispersed over thousands of acres.

A Sept. 3, 1973 baghouse fire at the Bunker Hill smelter in Kellogg followed a history of primary lead smelting there since 1917. Without proper filtration, emissions reached as high as 160 tons of particulate pollution a month, and researchers linked the fire to one of the worst childhood blood lead poisoning events in U.S. history. The smelter shut down in 1981. In 2011, EPA settled Hecla Mining Company’s Bunker Hill liabilities for $263.4 million plus interest.

Today, the cleanup effort is split among the state, the federal government and the Coeur d’Alene Tribe, with Lake Coeur d’Alene still serving as a major recreation and tourism asset and part of the tribe’s aboriginal homeland. Millions of tons of metals-laden sediment, including zinc, lead and cadmium, remain on the lake bottom, even though water quality improved from the mid-1970s as upstream mining tapered off, cleanup began and environmental rules tightened. Phosphorus levels have been rising again.

Governor Brad Little created the Coeur d’Alene Lake Advisory Committee in 2021 and set aside $2 million in Leading Idaho money to reduce phosphorus and improve water quality. Idaho later added $35 million in American Rescue Plan Act funds. The advisory committee asked for project ideas in August 2021, recommended funding for 19 projects and work on those projects continues through 2026.

DEQ’s 2025 recreational-area screening study, based on a 2022 National Academies recommendation, sampled 32 sites in summer 2024. All sites remained below cleanup action levels. Additional samples were collected in fall 2025 and reporting is still underway. The Coeur d’Alene Tribe judged the 2009 Lake Management Plan inadequate in 2018, and the state, tribe and EPA continue to discuss what further action is needed to manage hazardous wastes in lakebed sediments.