Spokane River Metals Island Complex

Contaminants from historic mining practices in Idaho’s Coeur d’Alene Basin washed downstream and settled in soil and sediment along some Spokane River beaches. 

The U.S. Environmental Protection Agency (EPA) conducted studies of the mining contaminants in the Coeur d’Alene Basin and began a wide-spread cleanup of the Bunker Hill Mining and Metallurgical Superfund Site. As part of the EPA study and studies Ecology conducted, nine beaches in Washington were cleaned up, including the Island Complex.

The Island Complex area is used for recreation and provides trails and access to the river from a parking lot near Exit 299 on I-90. The site is about 9.5 acres and is near river mile 95 about 1 mile west of the Idaho border. The northwest boundary is in the river, and the southeast boundary runs along the Centennial Trail and I-90.

The mining-related contaminants include arsenic, cadmium, lead, and zinc.

Ecology completed the cleanup in 2007:

• Erosion was reduced and contaminants isolated to limit human, wildlife, and fish exposure to metals contamination. 
• Sections of the Spokane River bank were stabilized to minimize re-distribution of contaminants. 
• A protective cap of soil and gravel was placed on certain trail areas and banks to prevent contact with contaminants. 
• Trail signs or boulders were installed as path guides. 
• A temporary irrigation system was installed along the bank of the channel for new trees and shrubs. 
• Trees and shrubs were planted along the bank of the back channel. 
• Existing footpaths were enhanced.

Ecology completed the first periodic review in 2022. The report is for all the Spokane River shoreline sites affected by mining contaminants. The purposes of the review are to evaluate site conditions about every five years when contaminants are capped and ensure the cleanup continues to protect human health and the environment.

The cleanups continue to protect human health and the environment from the capped contaminated sediments. However, contaminant concentrations have increased in some cases, and new contaminated sediments have been deposited on the caps. This likely means upstream sources are continuing to impact the river and could pose a risk to human health and the environment if they are not controlled.

We will continue monitoring to ensure that the sites continue to be safe for human health and the environment. A monitoring study evaluating sediments entering the site at the Washington-Idaho border would help assess the potential for recontamination.