Our Gem: Evaluating risk in Lake Coeur d’Alene recreational areas

The Coeur d’Alene River Basin, Lake Coeur d’Alene and the Spokane River are impacted by heavy metals from historic mining practices that began in the 1880s. This has resulted in the area being designated as an EPA National Priorities List (NPL) Site under the Comprehensive Environmental Response Compensation and Liability Act (CERCLA). The site was listed in 1983 and is known as the Bunker Hill Mining and Metallurgical Complex Superfund Site.

Although mining practices have evolved, in tandem with operations and their discharges being regulated to protect water quality, the Coeur d’Alene watershed continues to contend with the impacts of historic mining. 

Due to hazardous substances being released upstream and flowing downstream into Lake Coeur d’Alene, multiple studies have examined the water and sediments in Lake Coeur d’Alene. Collectively, studies have found that arsenic, cadmium, copper, lead, antimony and zinc, are present in sediments and water throughout the Coeur d’Alene River corridor, Lake Coeur d’Alene and downstream into Washington via the Spokane River, with some metals occurring in concentrations above natural background levels.

A 1998 study initiated by EPA, the Coeur d’Alene Tribe and Idaho Department of Health and Welfare focused on evaluating public shoreline recreation areas around the Coeur d’Alene Basin to determine if health risks from metals needed to be included in the ensuing Superfund remediation (aka cleanup) process. The study concluded that there were concerning levels of heavy metals at two Lake Coeur d’Alene locations – Harrison City Beach, where the Coeur d’Alene River empties into Lake Coeur d’Alene and Blackwell Island, where the lake outflows to the Spokane River. Harrison City Beach underwent cleanup by Union Pacific Railroad (UPRR) as part of the Trail of the Coeur d’Alenes Rails to Trails conversion and continues to be monitored by UPRR. Blackwell Island has not undergone remediation.

Today, as development and recreation have grown and time has passed, there is a need to reassess the potential presence of metals at both public and private recreational areas that may cause human health impacts. Per the Coeur d’Alene Lake Management Plan and the National Academy of Science’s “The Future of Water Quality in Coeur d’Alene Lake (2022),” the Idaho Department of Environmental Quality has launched an effort to develop and conduct a lake-focused risk-based evaluation of heavy metals exposure at recreational areas within the bounds of Lake Coeur d'Alene and Idaho portions of the Spokane River. These efforts are funded by Governor Little’s Leading Idaho initiative and encouraged by area residents.

In the summer of 2024, Alta Science & Engineering, in collaboration with DEQ, collected beach sediments, soils, and near-shore and open-water samples that will be used to conduct a human health risk-based evaluation. Samples were collected during the summer months to ensure they were representative of potential recreational exposure. The team diligently collected samples from 32 recreational sites, including popular beaches such as Cheamkwet Park, Sanders Beach, Tubbs Hill, Mica Bay, Harlow Point and Corbin Park. 

Samples collected were sent to a laboratory for analysis. Once the results are validated, they will be evaluated and compared to health-protective screening levels to characterize health risks. It is possible that potential risks, if any, may vary between recreation sites. 

Alta Science & Engineering will write a comprehensive risk evaluation report, anticipated to be published in early 2026. This evaluation will provide a current assessment of conditions that will enhance our understanding of metals impacts to sediment and water, identify areas of concern, and help prioritize next steps. The findings will ultimately allow our community to make informed decisions about how to protect our community and Our Gem, Lake Coeur d'Alene. 

In the meantime, families can protect themselves while recreating by eating before playing in beach areas, washing hands with soap and clean water before eating, and making sure children and pets are clean of beach sands/sediments before returning home. Make sure to eat on tabletops or other clean surfaces, such as a picnic blanket in grassy areas (not on the beach sand). For more information on playing clean in the Coeur d’Alene Basin, visit www.deq.idaho.gov/playclean. 

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The Our Gem Coeur d’Alene Lake Collaborative is a team of committed and passionate professionals working to preserve lake health and protect water quality by promoting community awareness of local water resources through education, outreach and stewardship. Our Gem includes local experts from the University of Idaho Coeur d’Alene and the Idaho Water Resources Research Institute, Coeur d’Alene Tribe, Idaho Department of Environmental Quality, Basin Environmental Improvement Project Commission, Kootenai County, Kootenai Environmental Alliance and the Coeur d’Alene Regional Chamber of Commerce.