Kaiser Mead NPL Site

Groundwater cleanup

Waste handling practices used by the Kaiser Aluminum Company from the 1940s to the late 1970s led to cyanide and fluoride contamination in part of the Spokane-Rathdrum Prairie Aquifer and the Little Spokane River. The groundwater plume is 145 feet below ground, 800 – 1,500 feet wide, and travels approximately 2.5 miles to the Little Spokane River. It then discharges into a series of springs.


A groundwater "pump and treat" extraction and treatment system required under a Consent Decree began operating in 2020 to address the contamination. This system:

• Extracts contaminated groundwater.
• Uses biological and physical treatment to remove cyanide and fluoride.
• Returns the treated water to the aquifer.

Other cleanup activities

There were other environmental problems on the rest of the former smelter site now owned by Spokane Recycling, LLC, which is a separate cleanup site. In 2020, the United States Environmental Protection Agency (EPA) conducted an emergency action to remove PCB-containing materials and other wastes.

Learn more about the EPA's work.

The former smelter produced aluminum at the Mead site for more than 50 years. The company went through closure and bankruptcy in the early 2000s.

Past groundwater cleanup actions

• In the late 1970s, Kaiser changed its waste handling practices and provided alternate water supplies for property owners whose wells were contaminated. The county put restrictions on new wells in the area.
• Wastes remaining on site were covered with an asphalt cap to keep rain and snow from leaching more contamination into groundwater.
• A series of investigations were conducted to understand the extent of contamination and evaluate the potential options to clean it up.

While these actions helped us understand the problem and control the risk posed by the site, monitoring showed that groundwater contamination continued. In 2019, we finalized a plan to help clean-up groundwater contamination by installing the groundwater extraction and treatment system.