Spokane River Metals Flora Road

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

Ecology completed cleanup work at the Flora Road site in 2009. A one foot cap of gravel material was placed over contaminated sediments along the Spokane River bank. Boulders moved during the construction were replaced. A portion of the access path from the Centennial Trail to the beach was enhanced with gravel material.   

Spring run-off in 2011 damaged portions of the protective cap that was placed over contaminated sediments. The 2012 project enhanced the previous work with an engineered cap that is designed to prevent future erosion.

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.