The city of Arcata flushes with pride!

“People are eating picnic lunches, enjoying the view of the bay and the marshes, and spotting the wildlife without ever realizing that they are smack in the middle of a wastewater treatment facility.” 

Arcata has a unique — and award-winning — approach to wastewater treatment. The bayside city uses oxidation ponds and freshwater marshes to clean wastewater through a mostly natural process involving bacteria, plants, and sunlight. Moreover, the treatment marshes don’t just clean the city’s wastewater. Known as the Arcata Marsh and Wildlife Sanctuary, the marshes cover more than 300 acres, providing bike paths, hiking trails, and scenic picnicking opportunities for residents, as well as a refuge for 300 species of birds. 

“We flush with pride!” Arcata City Manager Karen Diemer chuckled. “The city of Arcata’s treatment system is a great reuse of wastewater, providing residents and visitors a place to appreciate nature and open space in an urban setting, attracting several hundred users every day, participating in a wide variety of activities like walking, cycling, bird watching, dog walking, and picnicking.”

With the facility's once groundbreaking equipment deteriorating, officials have developed a two-phase project that replaces the 50-year-old parts and addresses new challenges. Phase 1 of the $64 million improvement project focuses on replacing parts, upgrading the treatment pond, and transitioning from chlorine disinfection to ultraviolet disinfection, removing the last part of the process that involves chemical treatment of the water. 

Phase 2 includes additional marsh and pond rehabilitation and the installation of an oxidation ditch — another pioneering process that uses the concept of the wetland system but in a highly enriched environment to speed up water treatment. The second phase also addresses the worrisome impact of climate change and the resulting rising of the bay.

“We are following the science and basing our planning on the measurement of the bay’s hightide over time,” said Diemer. “The bay will eventually reclaim our marsh treatment ponds, and so we are currently building one and planning for two oxidation ditches that will clean the water faster and more efficiently, so the outlying marshes could be phased out if and when they are no longer available.” 

The wastewater treatment improvement project — funded by a mixture of grants and loans — started in 2020 and is scheduled to be completed in 2025. The project is the city’s most expensive infrastructure project. “The second most expensive project was when we built the first one, says Diemer.”

The pandemic made crystal clear to both city officials and Arcata residents that investments in public and open spaces are invaluable. “The Arcata wastewater treatment and wildlife sanctuary averages over 300 people a day and that doubled during the pandemic,” noted Diemer. “People are eating picnic lunches, enjoying the view of the bay and the marshes, and spotting the wildlife without ever realizing that they are smack in the middle of a wastewater treatment facility. Even, if you don’t see the value right away, these spaces are the spaces people want to live in and thrive.”

A longer version of this story, which includes more information about the city’s sewage process, originally appeared in the July edition of Western City.   

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