A Single Golden Mussel Was Found in California in 2024. Now It Threatens Water for 27 Million People

Added: 2026-05-31

[00:00:01]It is a gray morning at the port of Stockton, California. October 17th, 2024. The Sacramento Sanwaqin Delta moves slow and muddy under a low ceiling of fog. Elizabeth Wells, a scientist with the California Department of Water Resources, is doing what she has done at this exact monitoring float for the better part of 2 years.

[00:00:25]She checks it, she photographs it, she moves on.

[00:00:30]This morning she does not move on.

[00:00:33]Attached to the underside of the float in a small cluster about the size of a half dollar are muscles she has never seen on this float before. Yellow gold, 2 cm long, striped, but not striped the way she knows.

[00:00:50]The month before, this float had been clean.

[00:00:54]She bags two specimens. She drives them to a lab.

[00:00:59]7 days later on October 23rd and 24th two independent laboratories UC Davis and the California Department of Food and Agriculture return the same answer.

[00:01:11]Limnoperna Fortuni, the golden muscle. It is the first time this species has ever been found in North America. And what Elizabeth Wells held in a small plastic bag that morning was, in [music] genetic terms, the front edge of an invasion 33 years in motion.

[00:01:31]It was here.

[00:01:36]The golden muscle is native to the freshwater lakes and rivers of China and Southeast Asia, Vietnam, Cambodia, Thailand, Korea, Indonesia. In its home range, it lives quietly under predation by fish that have been eating it for millions of years.

[00:02:20]In 1991, it escaped that home range. It turned up in the Rio de la Plata, the massive estuary system that drains southern Brazil, Paraguay, Uruguay, and northern Argentina. The likely vehicle was the same one that brought the zebra muscle to the Great Lakes 3 years earlier. the ballast tank of an international cargo ship.

[00:02:43][music] In the 33 years between 1991 and 2024, the golden muscle did to South America what the zebra muscle did to North America. It spread up rivers into reservoirs onto hydroelectric infrastructure into drinking water intakes and into ecosystems that had no defense against it. Then in October of 2024, it crossed an ocean.

[00:03:31]A note before we go further. Many of you watching know the zebra muscle and you know its close cousin, the quaga muscle, which arrived in the Great Lakes a year later in 1989 and has now replaced zebra muscles across much of the deep water.

[00:03:46]The golden muscle is not closely related to either one. It belongs to an entirely different family, closer in lineage to the marine blue muscle than to the dissonids. What it shares with zebra and quaga is one trait. It grows on hard surfaces in dense colonies [music] and it does not let go.

[00:04:08]But it does three other things zebra muscles cannot do. And those three things are why what arrived at the port of Stockton last October is not a repeat of 1988.

[00:04:20]It is something [music] worse.

[00:04:28]Before we talk about why, you need to know what is at the end of this pipeline. The Sacramento Sanwaqin Delta is the largest estuary on the west coast of the Americas. It is also the central hub of the California State Water Project, the network of canals and aqueducts that carries fresh water from the Delta South across the entire state to 27 million people and to 750,000 acres of farmland.

[00:04:57]Every drop of drinking water from San Jose to Los Angeles to San Diego in some way runs through this system. Every almond, walnut, tomato, and lettuce field in the central valley draws from it. The economic engine of the most populous state in the country sits at the end of this aqueduct.

[00:05:19]The golden muscle is now in the aqueduct. By July 2025, 9 months after Elizabeth Wells found her first specimen, golden muscles had been confirmed as far south as Riverside County, more than 400 m from the port of Stockton. They moved through the canal at the speed of the water itself.

[00:05:43]But the stakes do not stop at the California state line.

[00:05:50]If you live in Nevada, Arizona, Utah, or any of the western states that draw water from the Colorado River system, Lake Meade, Lake Powell, Lake Havsu, your reservoirs are connected by boats.

[00:06:12]The same trailered fishing boats that pull out of Lake Meade on Saturday morning launch in Lake Powell on Sunday afternoon. They carry between them every aquatic invasive species that any of those waters has ever held.

[00:06:29]Texas, Tennessee, Florida, the lower Mississippi.

[00:06:34]Every state with a reservoir, a marina, and a boat ramp is downstream of California in the only way that matters.

[00:06:42]The same boats travel between them.

[00:06:47]California is now under mandatory quarantine for boats moving between water bodies. Other states are watching, drafting their own rules, and counting the days.

[00:07:22]The first thing the golden muscle does that the zebra muscle cannot is this. It tolerates salt.

[00:07:30]For 36 years, scientists working on the zebra muscle invasion in the United States have relied on one specific biological limit. The zebra muscle cannot survive in water more than about 1/2 part per thousand salinity. It is a strict freshwater animal.

[00:07:49]Anywhere the river meets the ocean and the water turns brackish, the lower Hudson, the upper Chesapeake, [music] the broad mouths of the Mississippi, San Francisco Bay, Tampa Bay, the zebra muscle dies.

[00:08:04]That biological barrier is why 3/4 of America's coastal estuaries have stayed clear of the dryinned invasion for the last three decades.

[00:08:13]It is why the Chesapeake Bay still produces oysters. It is why Tampa is not Detroit.

[00:08:55]The golden muscle does not respect that barrier. Laboratory and field studies from South America have established the tolerance range. The golden muscle survives, breeds, and forms reefs in water salinities up to three parts per thousand. That is six times the limit of the zebra muscle. That number puts every brackish water estuary in the United States, every place a river meets the sea inside the survivable range.

[00:09:26]the Chesapeake Bay, the Hudson Estuary, Mobile Bay, the Gulf Coast of Florida, San Francisco Bay itself. The estuaries we thought were natural barriers are not barriers anymore.

[00:09:45]The second thing the golden muscle does is tolerate heat. The zebra muscle is a temperate zone animal. It thrives in cool water. It struggles in water above 30° C, about 86 F. That biological ceiling is the reason zebra muscles have spread aggressively across the Great Lakes and the upper Mississippi, but have moved slowly into the warm reservoirs of the American South.

[00:10:17]Texas reservoirs run hot in summer. Lake Travis, Lake Texoma, Falcon Lake.

[00:10:23]Florida lakes run hotter.

[00:10:28]Arizona's Colorado River impoundments, Lake Meade, Lake Havsu, Lake Mojave, can reach water temperatures the zebra muscle simply will not survive. This is the second reason the zebra muscle never finished colonizing the United States.

[00:10:44]The South was too warm.

[00:10:49]The golden muscle tolerates water up to 35° C, about 95° F, 5° higher than the zebra muscle's hard limit. That 5° shift opens every reservoir, [music] every river impoundment, and every irrigation lake in the southern half of the United States to invasion.

[00:11:12]The bass lakes in East Texas that were too warm for zebra muscle, they are not too warm for golden muscle. The Colorado River reservoirs in Arizona that have only been partly invaded by quagas, they are inside the golden muscles range. The Florida waterways that have never had a dryid invasion at all, they are inside the range too.

[00:11:40]If you fish anywhere in the southern United States, anywhere from the Carolas to the California Arizona line, the warm water refuge your reservoirs enjoyed for the last 36 years is gone.

[00:12:02]The third thing the golden muscle does is reproduce faster than anything we have on file in North American freshwater.

[00:12:09]A female zebra muscle releases roughly 1 million eggs over the course of one breeding season per year. That is the number that drove the invasion of the Great Lakes. The number that took a population from one accidental ballast dump in 1988 to colonization of all five Great Lakes by 1998.

[00:12:44]A female golden muscle releases approximately 1 million to 1 and a2 million eggs per spawning event. And golden muscles do not spawn once a year.

[00:12:54]In the warm waters of South America, they spawn multiple times per year, sometimes continuously across an extended warm season. The total annual reproductive output of a single golden muscle exceeds the zebra muscle by a factor of 2 to three. The larae, the velager stage, drift longer, settle on a wider range of substrates, and tolerate a wider range of water conditions during [music] the drift.

[00:13:28]The result is exponential population growth at a rate the zebra muscle could not match. Stack the three traits on top of each other. The golden muscle survives in salinity that excluded zebra muscles from coastal estuaries. It survives in water temperatures that excluded zebra muscles from the American South. And it reproduces two to three times faster than the zebra muscle did in its worst years.

[00:14:01]Whatever the zebra muscle has cost the United States, and we are still counting that bill at over 5 billion and over 1 billion every year in damages and control, the golden muscle will cost more in more places sooner.

[00:14:17]That is not a worst case projection. It is what the same species did over the last 33 years in South America.

[00:14:29]The Itypu Dam straddles the Piranha River and the border between Brazil and Paraguay. It is the second largest hydroelect electric facility on Earth.

[00:14:39]7.9 kilometers across. 20 generating units, roughly 80 million people in two countries depend on the electricity it produces.

[00:14:59]In 1998, the Golden Muscle reached the Yasirata Dam just upstream of Itipu.

[00:15:07]It's engineers immediately began a monitoring program for villagers and adults in the water column downstream.

[00:15:14]They have run that monitoring program continuously every year since 1998.

[00:15:24]They have spent millions of dollars annually on intake screen cleaning, on copper-based control treatments, on infrastructure modifications, on continuous biological monitoring. The largest hydroelectric facility in the Western Hemisphere cannot eliminate the muscle. It can only stay ahead of it.

[00:15:49][snorts] Argentine biologist Daniel Boltovskcoy who has studied the golden muscle for more than three decades from the University of Buenoses has been blunt in his published work. Once the golden muscle is established in a waterway, it does not go away. The only outcome available to managers is suppression.

[00:16:11]Indefinite, expensive, vigilant suppression.

[00:16:17]In 34 years of invasion, South America has not found an exception to that rule.

[00:16:33]Native South American fish, and there are about 50 species now documented as golden muscle predators, including the pipara and several large catfish, have taken 20 years to build into a measurable check on muscle populations.

[00:16:49]Even now, the best research suggests fish predation reduces muscle density by around 70% in zones where the fish complex is intact and protected. The North American Native Fish Complex has not had 20 years. It has had 14 months.

[00:17:16]It is a gray morning at the Port of Stockton, California, almost 18 months after Elizabeth Wells found a small cluster of golden yellow muscles on the underside of a monitoring float. The float is still there. It is no longer clean. It is no longer carrying one cluster.

[00:17:41]The muscles are now in three California counties, more than 400 m of state aqueduct, and an undisclosed number of inland reservoirs. The spread mapping has not yet caught up to mandatory boat inspections are now operating at 12 state launch ramps. The California Department of Fish and Wildlife has issued $1 million in grants to marinas. State biologists are working with the US Fish and Wildlife Service and the Bureau of Reclamation on a containment framework that is being drafted in real time, one outbreak update at a time.

[00:18:45]There is no bio control available. No specific predator, no specific pathogen, no species safe to release. There is only what we do. When the zebra muscle arrived in 1988, America took 36 years to watch it spread across 38 states. We spent $5 billion fighting it. We are still paying every line item on every water bill from Cleveland to Duth.

[00:19:46]The golden muscle has been in America for 14 months. It is already in three counties, one major aqueduct, and one of the largest water systems in the western United States. We have time to prepare.

[00:20:00]We do not have time to wait. The next 14 months will decide what kind of country we fish in for the next century.