New State Study Aims to Protect Drinking Water for 88,000 People

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Jennifer Kalt, Director


More than a decade after declaring an “Imminent and Substantial Endangerment” to public health from contaminated groundwater moving toward Mad River, the State Department of Toxic Substances Control (DTSC) is finally resuming work to determine the extent of the dioxin plume and to plan next steps to protect the region’s drinking water.

The site is in the unincorporated community of Glendale (near Blue Lake), approximately  one mile upstream of the drinking water supplies for nearly 90,000 people in the Humboldt Bay area. This includes Arcata, Eureka, McKinleyville, Blue Lake, and the Samoa Peninsula. 

DTSC consultants recently sampled groundwater and surface water on the site to identify how far contamination has spread toward Mad River from the former McNamara & Peepe Lumber Mill. The results will inform next steps to prevent toxic chemicals from reaching Mad River. The mill’s contaminants include the wood preservative pentachlorophenol (known as PCP or penta), which was banned in the 1980s for most uses due to high concentrations of dioxins – some of the most toxic and persistent chemicals ever manufactured.

This study comes two years after the DTSC decertified the 1998 cleanup, which involved “capping” the hotspot with concrete in an effort to prevent rainwater from mobilizing toxic chemicals further into groundwater and/or into Mad River. The cap failure is linked to a 15-foot rise in groundwater elevation, which has brought groundwater into contact with contaminated soil below the cap. This rise in groundwater is likely the result of the 2002 closure of an on-site well that the mill had pumped for decades. 

DTSC took responsibility for the cleanup in the 1990s, when the current landowner, Blue Lake Forest Products, filed for bankruptcy protection. McNamara & Peepe had previously also filed for bankruptcy protection, leaving the State to manage the toxic byproducts of these for-profit ventures.

In 2005, high levels of PCP were detected beyond the cap, moving toward an unnamed tributary of Hall Creek, a salmon-bearing stream that flows into Mad River. The 2008 ‘Imminent and Substantial Endangerment Determination’ declared that a response action was necessary because a release or threatened release of a hazardous substance may cause an imminent and substantial endangerment to public health, welfare, or the environment.

Since 2008, sampling was conducted and reports written, but it wasn’t until 2018 that DTSC decided the cap had failed to contain the contamination. A new cleanup plan, expected in 2019, was delayed to March 2021. Groundwater and surface water sampling in the next few months will help identify next steps. This move by the State follows two years of correspondence by the Humboldt Bay Municipal Water District urging the DTSC to sample in preparation for implementing a renewed clean-up plan for the toxic contamination at the site.

The Water District’s General Manager, John Friedenbach said, “We have been monitoring this site and DTSC for decades. Given the failure of DTSC’s Remedial Action Plan, we have increased our pressure on DTSC to design and implement a viable cleanup plan to safeguard the water supply for the Humboldt County residents that we serve.”

We will be reviewing the sampling results as well as DTSC’s plans for cleaning up and containing the contamination before it reaches Mad River. Working with Baykeeper’s scientific experts, Humboldt Bay Municipal Water District, Blue Lake Rancheria, Glendale residents, and others, we will keep the public informed while ensuring that our drinking water and the environment receive the best possible protections from degradation by these legacy pollutants.

More information is available at DTSC’s EnviroStor database at


Humboldt Bay Tours

Local bird lover Amaya Bechler has been guiding Baykeeper’s free, COVID-safe tours on the Eureka Waterfront and Hikshari’ Trails since July 2020. On March 7, we had the pleasure of seeing two Townsend’s warblers “gleaning” (foraging insects) in a Monterey cypress tree at Halvorsen Park. Many thanks to Amaya for sharing her enthusiasm and knowledge of birds, and to the California Coastal Conservancy for funding our Bay Tours program.