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Golden Mussel, California’s Newest Delta Invader, Is Likely Here To Stay – And Spread
WESTERN WATER NOTEBOOK: Aquatic hitchhiker adds to burden of invasive mussels challenging water agencies across the West

Image shows golden mussels clustered on a buoy, found during a survey in November 2024 at O'Neill Forebay at the foot of San Luis Reservoir in Merced County. The mussels were also discovered for the first time in North America last fall in the Sacramento-San Joaquin Delta and O'Neill Forebay. A new aquatic invader, the golden mussel, has penetrated California’s ecologically fragile Sacramento-San Joaquin Delta, the West Coast’s largest tidal estuary and the hub of the state’s vast water export system. While state officials say they’re working to keep this latest invasive species in check, they concede it may be a nearly impossible task: The golden mussel is in the Golden State to stay – and it is likely to spread.

Announcement

Registration Now Open for Popular Bay-Delta Tour in May; Water Summit Set for Oct. 1
Seats Filling Quickly for Water 101 Workshop and Central Valley Tour in April

Register today for the return of our Bay-Delta Tour May 7-9 as we venture into the most critical and controversial water region in California. Get a firsthand look at the state’s vital water hub and hear directly from experts on key issues affecting the Sacramento-San Joaquin Delta and San Francisco Bay.

The 720,000-acre network of islands and channels supports the state’s two large water systems – the State Water Project and the federal Central Valley Project – and together with the San Francisco Bay is an important ecological resource. You’ll learn firsthand how the drought is affecting water quality and supply that serves local farms, cities and habitat. Much of the water also heads south via canals and aqueducts to provide drinking water for more than 27 million Californians and irrigation to about 3 million acres of farmland that helps feed the nation.

Water News You Need to Know

Aquafornia news San Francisco Chronicle

Friday Top of the Scroll: When will the California storms end? Here’s when to expect sunshine to return

Scattered rain and mountain snow showers will continue across Northern and Central California on Friday morning. But stormy conditions will fade across California by the evening, giving way to generally quiet weather for the three-day holiday weekend. Continued showers could add up to an additional foot of snow in the Sierra Nevada above 5,000 feet, with the heaviest snowfall in the morning and midafternoon Friday. Travelers heading across the Sierra for the holiday weekend should prepare for winter driving conditions. In the Bay Area, rain showers will be more hit-or-miss than Thursday’s widespread precipitation. 

Other rain, snow and flood news:

Aquafornia news Los Angeles Times

Groundwater deep beneath L.A. area slow to recharge, study finds

The rainstorms that drenched Southern California two years ago weren’t enough to replenish deep underground aquifers that had been depleted by pumping over the last two decades, a new study has found. Stanford University scientists analyzed how the historic 2023 storms affected groundwater levels across Los Angeles and Orange counties. They found that while shallow aquifers rebounded, deeper aquifers more than 150 feet underground regained only about 25% of the water they had lost to pumping since 2006.

Other aquifer and reservoir news across the West:

Aquafornia news Water Education Foundation

Golden mussel, California’s newest Delta invader, is likely here to stay – and spread

A new aquatic invader, the golden mussel, has penetrated California’s ecologically fragile Sacramento-San Joaquin Delta, the West Coast’s largest tidal estuary and the hub of the state’s vast water export system. While state officials say they’re working to keep this latest invasive species in check, they concede it may be a nearly impossible task: The golden mussel is in the Golden State to stay – and it is likely to spread.

Other invasive species news:

Aquafornia news San Francisco Chronicle

Northern California river gets major dam removal deal

The push to remove two dams on Northern California’s Eel River, making it the longest free-flowing river in the state, took a step forward Thursday with a major agreement among clashing communities. The agreement, which unites local, state and tribal leaders behind the retirement of PG&E’s Potter Valley hydroelectric project and its two dams, promises “restorative justice” compensation for the region’s indigenous people and continued water exports to the Russian River basin, where the PG&E facility has long sent supplies. … Most fundamentally, it would raise river levels and give struggling salmon and other fish access to spawning habitat blocked by the dams for more than a century.

Related articles:

Online Water Encyclopedia

Wetlands

Sacramento National Wildlife RefugeWetlands are among the world’s most important and hardest-working ecosystems, rivaling rainforests and coral reefs in productivity. 

They produce high oxygen levels, filter water pollutants, sequester carbon, reduce flooding and erosion and recharge groundwater.

Bay-Delta Tour participants viewing the Bay Model

Bay Model

Operated by the U.S. Army Corps of Engineers, the Bay Model is a giant hydraulic replica of San Francisco Bay and the Sacramento-San Joaquin Delta. It is housed in a converted World II-era warehouse in Sausalito near San Francisco.

Hundreds of gallons of water are pumped through the three-dimensional, 1.5-acre model to simulate a tidal ebb and flow lasting 14 minutes.

Aquapedia background Colorado River Basin Map

Salton Sea

As part of the historic Colorado River Delta, the Salton Sea regularly filled and dried for thousands of years due to its elevation of 237 feet below sea level.

The most recent version of the Salton Sea was formed in 1905 when the Colorado River broke through a series of dikes and flooded the seabed for two years, creating California’s largest inland body of water. The Salton Sea, which is saltier than the Pacific Ocean, includes 130 miles of shoreline and is larger than Lake Tahoe

Lake Oroville shows the effects of drought in 2014.

Drought

Drought—an extended period of limited or no precipitation—is a fact of life in California and the West, with water resources following boom-and-bust patterns. During California’s 2012–2016 drought, much of the state experienced severe drought conditions: significantly less precipitation and snowpack, reduced streamflow and higher temperatures. Those same conditions reappeared early in 2021 prompting Gov. Gavin Newsom in May to declare drought emergencies in watersheds across 41 counties in California.