Healthy river, healthy fish: Another record-breaking year for salmon returns on the Mokelumne River

Clements, CA – East Bay Municipal Utility District (EBMUD)’s partnership with state and federal natural resources agencies continues to yield great success on the Mokelumne River, where 17,474 Chinook salmon have migrated back to the Mokelumne River during the 2018 fall run. After record-breaking returns of nearly 20,000 salmon in 2017 -- the highest-ever recorded on the river since 1940 -- the 2018 returns were the third highest and are 326 percent of average, continuing a streak of high returns dating back to 2011.

Strong fish returns signal a healthy river system. The Mokelumne River supplies water to homes and farms in Amador, Calaveras, Alpine and San Joaquin counties and 1.4 million East Bay customers.

“The best news is the amount of natural spawning we are seeing. This year the in-river spawning population of 10,194 salmon resulted in a record 2,432 redds or nests,” said Jose Setka, EBMUD Manager of Fisheries and Wildlife. “To date, the number of naturally produced juveniles that have left the river is more than 2.8 million. The strategies we are implementing are working, and the Mokelumne River is a welcoming home where salmon can survive and thrive.”

Although the Mokelumne River is one of the smallest tributaries to the Delta contributing approximately 3 percent of flows into the Delta, its salmon population comprised approximately 43 percent of the commercial and 33 percent of the recreational catch off the coast of California. The Mokelumne River contribution to the ocean food web, the salmon industry and fishery businesses is significant, even as fishery returns in other parts of the Central Valley experience historical lows. 

“The Mokelumne hatchery is providing by far the most fish per capita to the ocean fisheries of any of the Central Valley hatcheries,” said John McManus, president of the Golden Gate Salmon Association. “We look forward to a time when the state allows EBMUD to capture and move naturally spawned salmon from the lower Mokelumne River to save them from being lost to the Delta pumps.”

 The fall returns are a result of efforts including:

  • moving the release location of hatchery fish to Jersey Point in the Delta to increase survival and reduce chances of fish straying to other rivers
  • releasing pulse flows in the fall to attract fish
  • restoring gravel habitat to encourage natural spawning
  • using tagging data to evaluate and improve hatchery release strategies such as transporting juvenile salmon by barge and feeding them a specialized diet to assist the fish in transferring from freshwater to seawater.

Engagement from a diverse group of stakeholders is the key to implementing management actions that lead to positive outcomes in the Mokelumne River. The fishery is prospering thanks to a collaborative partnership between EBMUD, United States Fish and Wildlife Service and the California Department of Fish and Wildlife. Other stakeholders within the Mokelumne watershed contributing to this sustained recovery include the National Marine Fisheries Service, North San Joaquin Water Conservation District, Woodbridge Irrigation District, landowners, and a number of environmental organizations.

“The success of the salmon returns this year offers proof that when good science meets collaboration, everybody wins,” said EBMUD Board President Marguerite Young. “This is a formula we will continue to use in the years to come.”

Less than a decade ago the Mokelumne River experienced one of the worst salmon returns on record. Looking ahead, overcoming the challenges of variability in weather conditions and water operation impacts in the Delta will be the focus of resource agency strategies to maximize salmon survival and protect the health of California’s fish and the Mokelumne River.

“By improving habitat, updating hatchery practices, better coordinating Delta operations and continuing scientific studies,” said Jose Setka, EBMUD Manager of Fisheries and Wildlife, “the Mokelumne River fish population will be model for recovery.”


Andrea Pook
Senior Public Information Representative