Perhaps the most serious threat to the Bay ecosystem is the presence of numerous contaminated industrial facilities and properties. For several decades timber companies used the fungicide pentachlorophenol ("penta") to preserve lumber at their mills. Penta is itself a potent carcinogen, but, more importantly, commercial-grade penta contains dioxin. As it is one of the most sinister reproductive and developmental toxins on the planet, there is no safe level of exposure to dioxin. In addition, the chemicals were often applied sloppily, using massive dip tanks and spray operations, and nearly all mills that treated wood are now contaminated with dioxin. Because it is so persistent in the environment, dioxin continues to be discharged from these mills into local streams, rivers, and into Humboldt Bay.

The former Simpson Plywood Mill in Eureka and an adjacent drainage swale that discharges directly into Humboldt Bay was heavily contaminated by dioxins and furans. Through Humboldt Baykeeper’s Toxic Initiative, this ongoing threat to Humboldt Bay was identified, and is currently undergoing clean up activities to eliminate this source of dioxin. 

At left: hazardous waste contractors remove contaminated soil adjacent to the Eureka waterfront site where plywood was sprayed with a pentachlorophenol mixture that contaminated the wetland channel.  Superfund levels of dioxin were found in the channel, which is hydrologically connected to Humboldt Bay and Palco Marsh.



Photo: Pulp mill on the Samoa Peninsula.

Humboldt Baykeeper watchdogs projects and proposals around the Bay, advocating for dioxin analysis in all projects that involve the disturbance of Humboldt Bay sediments. This advocacy work prevents backsliding on the strides we have made to develop broad-based awareness and understanding of the contamination issues that impact Humboldt Bay.  

Other sources of dioxin contamination also exist, including two former pulp mills which continue to be potential sources of contamination.

For more information on our Toxics Initiative and Enforcement Program, click HERE