Butcher Slough meanders through the Arcata Marsh & Wildlife Sanctuary, a popular natural area adjacent to Humboldt Bay. Shorebirds, ducks, herons, and egrets forage along the channel, making it a great place for bird-watching. What we can’t see is the toxic legacy of the timber industry, which left dioxins, metals, and other contaminants here and at many other mill sites around Humboldt Bay. Drone image by Oren Nardi, Jan. 2024. The reach of this waterway we call Butcher Slough is the tidally-influenced stretch of Jolly Giant Creek, which flows from its headwaters in the Arcata Community Forest, under Highway 101, through Shay Park and beneath downtown Arcata, where it has been “daylighted” in several places. It then traverses the Arcata Marsh and Wildlife Sanctuary, making its way into Humboldt Bay near Klopp Lake and the City’s Wastewater Treatment Facility.Until the mid-1940s, the Arcata Marsh and Wildlife Sanctuary was mostly salt marsh. In 1945, the first log deck was built on filled wetlands near the railroad tracks that ferried lumber to ships docked at the Arcata Wharf. The first sawmill was built in 1946 along South G Street where the Marsh Interpretive Center stands today. By 1950, several mills and a log pond had replaced the former wetlands (lower left). These mills eventually closed and were demolished in 1976, after which the property was donated to the State of California.Throughout the years that these mills operated, they used a wood preservative called pentachlorophenol (“PCP”). Freshly-sawn boards were dipped into vats or sprayed with PCP, which contained dioxins, various compounds now recognized as some of the most toxic, persistent chemicals ever manufactured. Throughout the mid-20th Century, industrial chemicals were often handled carelessly because their long-lasting effects on human health and the environment were not yet understood.Dioxins accumulate in fatty tissue and magnify in animals that eat higher up in the food web. They are known to cause cancer and birth defects, and are infamous as a component of Agent Orange, the aerial defoliant used by the U.S. military to clear vegetation during the Vietnam War. Most meat and dairy products contain low levels of dioxins, which are also produced by combustion of wood and fossil fuels. But the concentrations of these chemicals on former mills around Humboldt Bay can be very high – and we know what needs to be done to remediate soil and groundwater to protect the bay and its wildlife.In 1986, the City of Arcata received state funding to restore Butcher Slough. A new slough channel was dug through the spot where PCP was used at the former mill building (lower right). Shortly after restoration began, the use of PCP was prohibited with the exception of utility poles, which are still treated with it today. (Although long overdue, the good news is that the U.S. EPA recently announced it would phase out PCP entirely by 2027.)In 2006, Humboldt Bay was designated as “Impaired” by dioxins, raising awareness of the need to address dioxin sites that continue to impact the bay ecosystem. Humboldt Waterkeeper works to identify contaminated sites near the Bay and other waterways to ensure that they are cleaned up – or at the very least, to ensure that contamination isn’t unknowingly mobilized by development or left in place in restoration sites.In 2018, we sampled sediment from Butcher Slough and found high concentrations of dioxins. That led to the development of a 2021 grant proposal with the City of Arcata that secured $215,420 from the U.S. EPA Brownfields Program to assess contamination at the site. Extensive sampling was done in 2022, leading to recommendations for cleaning up the site. The City recently received $400,000 from the State to develop a cleanup plan, beginning with a community engagement that is being planned for later this year.
Cleanup of contamination in and around Butcher Slough has been a top priority for Humboldt Waterkeeper for many years. We are grateful to the City of Arcata, U.S. EPA, and the Department of Toxic Substance Control’s Equitable Community Revitalization Grant Program for recognizing the importance of restoring ecosystem health to Butcher Slough and Humboldt Bay.
