Chemicals from former lumber mills found in high concentrations
Chemical leftovers from Humboldt County’s once booming timber industry could create costly delays for two Arcata projects near its marsh and wildlife sanctuary.
One project seeks to construct a dog park at the old Little Lake Industries lumber mill site on South I Street. The other would reuse dredged soils from the bay to create a buffer to protect city properties from sea level rise.
However, recent tests of Humboldt Bay sediment along the marsh found a “hot spot” of harmful compounds known as dioxins, according to Humboldt Baykeeper Director Jennifer Kalt. Dioxins are found in a wood preservative once used by many of the nearly 100 mill sites near Humboldt Bay, which had either spilled or had been dumped into the bay over the decades, Kalt said. “It was so toxic that it was restricted in the late 1980s,” Kalt said. “It’s only allowed now to be used on power poles.”
Finding a source
The dioxin levels found in the city’s tests in July 2015 were nearly 10 times the concentration deemed safe for exposure.
Due to the historic lumber mill activity along the bay, Arcata Environmental Services Director Mark Andre said it’s too early to determine the source of the dioxins. The city has hired an environmental consulting agency to find the sources and assess their impacts before proceeding with any of the projects, Andre said.
“There were many mills that drained toward where we did the sampling,” he said. “There were probably a dozen potential historic sources of dioxin that could have been a contributing factor. I’m not surprised that there is some level of dioxins found in the bay mud there.”
The city has been working to redevelop the mill site for some time now, with the latest proposal seeking the creation of a dog park.
Arcata Dog Park Working Group member Pamela Brown said she met with Arcata City Manager Karen Diemer at the beginning of the month to discuss the dioxin issue.
“It’s not a major concern because we really don’t know if it’s an issue for a dog park,” Brown said. “There is different level of concern depending on how the land is used. It was our understanding a year ago that this was dealt with and not an issue.”
At the same time, the city is seeking to build a buffer near the marsh to protect vulnerable city facilities like the wastewater treatment plant from the impacts of sea level rise. The city received an $86,000 grant from the California Coastal Conservancy in 2014 to design and permit the project, which would create 22 acres of protective salt marshes on the bay side of the rock levees that currently surround the marsh.
The sediment tests were conducted as part of this project as the city is seeking to use dredged bay mud to create the new marshes, Andre said. As to whether the high chemical concentrations in the soils will jeopardize the project, Andre said it would not and that much more research must be done to determine the source of the chemicals.
The former site of the Little Lake Industries mill between the Arcata Marsh and Samoa Boulevard is a noteworthy candidate for being the source of a dioxin “hot spot” found in bay mud near the southern side of the marsh last July.
“We’re going to ask our consultants to look at that closely before we proceed,” Andre said. “... I don’t think you can infer (the dioxin) came from Little Lake.”
Kalt said that the proximity of the Little Lake Industries mill to the marsh as well as the historically high levels of dioxin found at the site make it a noteworthy candidate.
Arcata purchased the old mill property in 2001 and conducted site analyses in 2004, which included data on dioxin concentrations. The two samples tested at the site showed dioxin levels that were over 100 times higher and 1,000 times higher than the safe exposure levels.
“This indicates that there is a dioxin issue at the site that may require further consideration before development,” the 2004 report states.
These results were surprising for Kalt.
“Much to my shock and dismay, the city detected dioxin there in 2004 and put the records on the shelf and didn’t do anything about it,” Kalt said.
Should it come to a point where Arcata will need to rid the Little Lake mill property of dioxins, Kalt said it will be an expensive process.
However, she said the benefits to the environment and to human health outweigh the costs. If consumed, dioxin can cause cancer and reproductive defects.
Kalt said dioxin can be produced by several other sources, including the combustion of fossil fuels. “The reality is that dioxin is fairly ubiquitous in the environment,” she said.
On the North Coast, dioxin contamination is most notably caused by lumber mills, Kalt said, which failed to prevent its wood preservatives from draining into the bay or intentionally dumped it there. The California Water Resources Control Board listed Humboldt Bay as an impaired water body in 2006 because of the presence of dioxins.
While dioxins can only break down over generations of time, Kalt said that does not mean there are not ways to remove them.
Humboldt Baykeeper and the Californians for Alternatives to Toxics sued the Simpson Timber Company in 2006 after tests at the company’s plywood mill near the Del Norte Street pier in Eureka showed very high concentrations of dioxins.
The case settled in 2008 with Simpson agreeing to remove several tons of contaminated soils, which was estimated to cost about $500,000.
The cleanup paid off in Kalt’s view, who said recent tests conducted at the Simpson Timber Co. site two weeks ago detected no dioxins.