The evening sun reflects of dioxin contaminated mud at low tide on Dec. 1 at the Arcata Bay shoreline | Photo by Jen Kelly
The evening sun reflects of dioxin contaminated mud at low tide on Dec. 1 at the Arcata Bay shoreline | Photo by Jen Kelly

Climate change puts the heat on clean up of dioxin hotspot

Vice Mayor alerts City Council to Arcata Bay Shoreline dioxin threat

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Vice Mayor alerts City Council to Arcata Bay Shoreline dioxin threat

City Council Vice Mayor Paul Patino said he intends to pull the approval of the Wastewater Treatment Facility Plan and Plant Improvement Project from the items scheduled to be rubber stamped by the city council.

The $60 million investment is a response to the threat of sea level rise which involves enlarging levees around the Arcata Wastewater Treatment Facility. Patino is calling on the council to further discuss the project after he learned the mud around the bay shoreline of the wastewater facility has the highest levels of dioxin ever discovered in Humboldt Bay sediments.

“I don’t see how you could mess with that area without it affecting that dioxin,” Patino said. “I think we need to get clear here.”

Dioxin can cause birth defects, cancer and organ failure. It is known to undergo bioaccumulation, meaning it increases in toxicity as it moves up the food chain from plants to predators. It was widely used from the 1940s to the 1980s before the EPA started regulating its use.

Patino raised particular concern with the staff report in the council packet where it states, “This project would involve enlarging the levee surrounding the majority of the outer perimeter of the Arcata Wastewater Treatment Facility (AWTF) by increasing the levee’s height and volume.”

The Arcata City Council is faced with the choice to approve the final application for the project, or first investigate the dangers of the dioxin believed to be largely the result of pentachlorophenol used during historic lumber mill operations up Jolly Giant Creek several blocks south of the town square.

The city is only now beginning to grapple with the impact the very high levels of dioxin have on plans to increase the height and volume of dikes around the marsh wastewater treatment facility and prepare for rising sea level already beginning as a result of climate change, and sea-level rise could complicate cleaning the dioxin.

“Disturbingly, the site near the Arcata Marsh was found to have the highest levels of dioxin ever documented in Humboldt Bay sediments to date (38 parts per trillion),” wrote Jennifer Kalt, director of Humboldt Baykeeper in the report New Dioxin Data: Good News, Bad News.

Kalt said she learned of the high dioxin levels from the report 2015 Feasibility Study: Beneficial Reuse of Dredged Materials for Tidal Marsh Restoration and Sea Level Rise Adaptation in Humboldt Bay, California.

The dioxin hotspot extends from the end of Butcher’s Slough, where Jolly Giant Creek hits the bay several blocks south of the plaza, to over 2,000 feet on either side along the bay shoreline: around the wastewater treatment facility on one side, and around the main Arcata Marsh parking lot and boat launch on the other side.

While Kalt acknowledged that many mills have existed along Jolly Giant Creek, she said, “We do know that Little Lake Industries was one source [of the contamination] because the city got a Brownfield grant…and found it around where the mill used to be.”

The council signed off on a grant application in October for $300,000 to clean up the Little Lake Industries property 17 years after pentachlorophenol was first discovered in levels exceeding federal benchmarks. The Environmental Protection Agency identified high levels of pentachlorophenol onsite in their 2003 report South I Street Mill Reuse Project, Arcata, California, Targeted Brownfields Site Assessment Phase II Investigation, Final Report.

Aldaron Laird is an environmental planner that specializes in sea level rise vulnerability assessments for Humboldt Bay.

“With rising water elevations [the dikes] could be overtopped maybe as early as 2050…on a monthly basis…We really only have 20 to 40 years to relocate all of that utility and transportation infrastructure to higher ground before it is inundated,” Laird said.

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