Friant Water Authority warns golden mussel infestation confined to lower Friant‑Kern Canal; $3 million treatment, dewatering planned

Friant Water Authority staff told the Tulare County Water Commission that invasive golden mussels discovered in California’s Delta have been found downstream in the lower reaches of the Friant‑Kern Canal and that the authority is taking a multi-pronged approach to control and monitoring.

"Golden mussels were discovered in the Delta October 2024," said Katie Duncan, senior water resources engineer for the Friant Water Authority. She said the authority first found mussels in the Friant‑Kern Canal in December 2025 and that current evidence suggests the infestation is isolated to about the lower 30 miles near the Kern County line.

Duncan described a golden‑mussel strategy focused on coordination with partner agencies (including Kern County Water Agency, Reclamation, state parks and the U.S. Army Corps of Engineers), control tools developed with consultant Dudek and expanded monitoring. "We're working with Dudek…to chemically treat golden mussels in the canal, develop a control plan, and fully assess the Friant‑Kern Canal," she said, and added the authority is preparing an MPDES permit to support treatment operations.

She emphasized the authority’s triennial dewatering as a critical management tool: "Dewatering for the Friant‑Kern Canal is what I'm calling our superpower," Duncan said, explaining that dewatering allows staff to desiccate mussels, inspect infrastructure, perform hot‑water washing and target chemical treatment where desiccation is not possible.

Duncan said the authority expects to budget at least $3,000,000 next year for continued chemical treatment and to "reset our canal" before moving toward sustained long‑term controls. She also warned that reverse‑flow operations and the Cross Valley Canal are the main vectors for reintroduction; the authority plans complementary treatments and, when permitted, injection copper treatment for water returning from the CVC. "It's not ideal. There's no guarantee it's a 100% kill," she said.

In question-and-answer exchanges, commissioners asked whether mussels have spread within infrastructure and whether treatment costs would fall to districts or growers. Duncan said the infestation appears to be getting denser in known areas and that cost‑recovery rules normally assign reverse‑flow operation costs to the districts that request that water, while other treatment and maintenance expenses are allocated among Friant contractors.

Duncan noted that several jurisdictions have declared emergencies (Kern County, San Joaquin County, Sacramento County and the city of Stockton) and advised the commission there is unlikely to be a single cure: "We're gonna be living with golden mussels for a long time," she said.

The commission asked staff to keep the item on future agendas, especially after the canal’s scheduled dewatering. Friant officials said they will coordinate updates with county staff.