Unstoppable invasion: How did mussels sneak into California, despite decades of state shipping rules?

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After the recent discovery of a destructive mussel in the Sacramento-San Joaquin River Delta, some experts say California officials have failed to effectively enforce laws designed to protect waterways from invaders carried in ships’ ballast water. 

A state law enacted 20 years ago has required California officials to inspect 25% of incoming ships and sample their ballast water before it’s discharged into waterways. But the tests didn’t begin until two years ago — after standards for conducting them were finally set — and testing remains rare. State officials have sampled the ballast water of only 16 vessels out of the roughly 3,000 likely to have emptied their tanks nearshore. 

Experts say stronger regulations are needed, as well as better enforcement. 

“It’s not really a surprise that another invasive species showed up in the Delta,” said Karrigan Börk, a law professor and the interim director of the UC Davis Center for Watershed Sciences. “It’s likely to continue happening.”

Native to eastern Asia, the mussels — detected near the Port of Stockton, in a small San Joaquin Valley reservoir and several other Delta locations — were the first to be detected in North America. If the mollusc evades eradication efforts, it could spread over vast areas of California and beyond, crowd out native species and clog parts of the massive projects that export Delta water to cities and farms. 

Ted Lempert, a former Bay Area Assemblymember who authored a 1999 state law aimed at preventing ships from bringing invasive species into California, said state officials “apparently took their eyes off the ball.”  

“We were trying to get ahead of the game, so I’m really frustrated that after all these years some of the events we were trying to prevent have come to pass,” he said. 

But the prospect of an invasive species colonizing a new region frequented by ships “is a numbers game” that can happen even under the most rigorous regulations and enforcement, said Greg Ruiz, a marine ecologist with the Marine Invasions Research Laboratory at the Smithsonian Environmental Research Center. “This is not a failure in the system,” he said.

Ballast water is stored in tanks to stabilize vessels at sea. Often taken on at the port of departure and released at the port of arrival, it is a global vector of invasive species, including pathogens that cause human diseases.

“We were trying to get ahead of the game, so I’m really frustrated that after all these years some of the events we were trying to prevent have come to pass.”

Ted Lempert, former Bay Area Assemblymember

To address the threat to ecosystems and water supplies, the State Lands Commission, the U.S. Environmental Protection Agency and the U.S. Coast Guard enforce a suite of overlapping regulations. 

The goal of these state and federal rules is to reduce as much as possible the number of living organisms in discharged ballast water. Vessel operators can achieve this by exposing their ballast water to ultraviolet light, filtering it and treating it with chlorine, which is then removed before discharge. 

‘Highest standards in the world.’ But are they enforced?

About 1,500 ships a year entering California waters release ballast water, according to Chris Scianni, environmental program manager of the State Lands Commission’s Marine Invasive Species Program. To check for compliance, officials board and inspect nearly all of them, plus another thousand vessels prioritized for inspection for other reasons, Scianni said.

During these inspections, officers review ballast water logbooks and reporting forms, interview crew members, inspect water treatment equipment, and occasionally take water samples for testing. 

“We’re the only entity in the world that’s doing this right now,” Scianni said.

A 2003 state law declares that the State Lands Commission “shall take samples of ballast water, sediment, and biofouling from at least 25% of vessels” subject to invasive species regulations. But commission officials told CalMatters they interpret it to mean that 25% of ships must be inspected, with no specific requirements for sampling. 

Sampling for some ships began in 2023, after the commission enacted standards for how the tests are conducted. It’s a considerable endeavor: A cubic meter of water  — which weighs a metric ton — must be collected from a ship. It can take an hour to draw, and it must be done while the vessel is actively discharging. Hours more may pass before results are ready.  

Federal officials have their own ballast oversight program. It leans on a system of self-reporting by vessel operators — which critics consider a weak tool for ensuring compliance. An EPA spokesperson said the agency “can assess compliance with (the rules) either through a desk audit or an on-site inspection.”

Many experts told CalMatters that the state and federal limits on how many organisms are allowed in discharged water are adequate but that enforcement is lacking. 

“We had the highest (ballast water management) standards in the world, but they were never actually enforced because the state couldn’t come up with a set of technologies to implement them,” said Ben Eichenberg, a staff attorney with the group SF Baykeeper.  

Ted Grosholz, a professor emeritus with the UC Davis Coastal and Marine Sciences Institute said “the standards are very exacting…The problem we have is compliance. How many ships coming in with ballast water can we really sample and verify? Enforcement officials can’t watch everyone.”

“The standards are very exacting…The problem we have is compliance. How many ships coming in with ballast water can we really sample and verify? Enforcement officials can’t watch everyone.”

Ted Grosholz, UC Davis Coastal and Marine Sciences Institute

Smithsonian’s Ruiz said state records show that all documented ballast discharges at the Port of Stockton since 2008 have followed state regulations.

Ships that discharge, however, occasionally remain uninspected as they enter a port. And some vessel operators may cheat, filling their ballast tanks with clean ocean water to pass off a faulty water treatment system as functional. Moreover, even treated ballast water can contain high levels of zooplankton. 

Ruiz, who has studied California’s data on ship arrival and locations of the mussels, said it’s probable the golden mussel entered the Delta at least a year ago and even possible that it’s been there for a decade or more, adding that “it could even have happened in the pre-treatment (of ballast water) era.”

Somehow, the creature slipped through the cracks and made itself a new home in what has been called one of the most invaded estuaries on the planet. 

It’s an outcome that Lempert as an assemblymember tried to prevent a quarter-century ago, when he authored the Ballast Water Management for Control of Non-indigenous Species Act. The law required incoming vessels to either retain their ballast water, drain it while simultaneously refilling with new water hundreds of miles out at sea, or use an “environmentally sound” treatment system. It tasked the California State Lands Commission with monitoring vessels for compliance. 

California has since enacted a complex system of regulations: In 2003, the Marine Invasive Species Act expanded the scope of Lempert’s legislation. Three years later, the Legislature required the commission to set limits on organism concentrations in ballast water; these “standards of performance” were implemented in 2022. While the standards allow minute levels of organisms in the water, the goal is “zero detectable living organisms” by 2040. 

Several federal laws also aim to protect U.S. waters from creatures like the golden mussel. 

Penalties for breaking ballast management rules have been modest. At the state level, violations have resulted in 24 fines in the past six years, totaling just over $1 million. Federal fines are rare, with just nine penalties issued amounting to about $714,000 in the EPA’s Pacific Southwest region since 2013.

Commission officials said “the frequency of noncompliant discharges … has dropped dramatically since our enforcement regulations (with penalties) were adopted in 2017.”

Can ballast water be sterilized?

California officials say achieving the law’s goal of zero organisms in ballast water discharged into waterways is infeasible. It would require a network of treatment plants at coastal ports, costing $1.45 billion over 30 years. The shipping industry would face another $2.17 billion in costs for installing systems capable of transferring ballast water to the floating treatment plants. 

But Eichenberg said some ships already use commercially available systems that consistently, and by a wide margin, outperform industry standards. He said the state’s failure to require that vessels use the most advanced treatment systems available — technology capable of nearly sterilizing ballast water — has culminated in the golden mussel’s arrival. 

“Something like this was bound to happen eventually,” he said.  

State and federal performance standards — modeled after international standards — limit the concentration of living zooplankton-sized organisms, like mussel larvae, in ballast water before discharge to 10 per cubic meter. For smaller organisms, allowances are higher. 

But even in ballast water that has undergone treatment in approved systems, zooplankton concentrations can be off-the-charts for reasons not always clear, according to Hugh MacIsaac, an aquatic invasive species researcher at the University of Windsor in Ontario, who has studied the spread of the golden mussel in South America and central China. 

Treating ballast water doesn’t necessarily work. A study in Shanghai found up to 23,000 zooplankton-sized organisms per cubic meter in the ballast water of half of ships sampled, MacIsaac said. 

Ruiz, at the Smithsonian research center, said the study’s sample size of 17 ships is too small to be representative and that such high concentrations are abnormal in the United States. “We sample vessels here, and that’s not what we see coming into the U.S.,” he said. 

Ship operators have shifted radically in the past 20 years “from no management to a nearly complete use of open-ocean exchange to, now, an almost complete transition to ballast treatment technology,” Ruiz said.

Attention turns to federal rules

The federal government, not state agencies, will soon become the key player in ballast management. That’s because new EPA rules, which are likely at least 18 months away from full implementation, will preempt state regulations.

The new rules — which state officials will help enforce — will keep the existing standards for organism concentrations, but prevent states from implementing their own rules that exceed federal standards. For example, California’s goal of zero detectable organisms in ballast discharge will be nixed. 

Nicole Dobrosky, the State Lands Commission’s chief of environmental science, planning and management, said states can petition the federal government for changes to the rules. 

Shippers welcome the shift to national rules that align with international standards, said Jacqueline Moore, Long Beach-based vice president of the Pacific Merchant Shipping Association. 

“An international industry by nature, the maritime community always appreciates consistent standards across the board, and across the ocean in this case,” Moore said. “It’s much easier for everyone.”  

“We have the technical ability to efficiently remove or kill organisms that are trapped in a tank of water. For half a century federal law has required EPA to …protect the environment and public health — yet EPA still refuses to do so.”

Environmental groups in a letter to Biden

But the change of regulatory oversight concerns Marcie Keever, the oceans and vessels program director with Friends of the Earth. She said that to date the State Lands Commission has been the more active enforcer.

Preempting state laws with federal standards that she says are too weak “will essentially give the shipping industry a free pass to pollute…These shipping companies are self-reporting pollution instances, and no one is doing anything about it except for the state.”

In 1973, the EPA exempted ballast water from the Clean Water Act. Eventually forced by court rulings to comply with the act, the agency released its newest standards in October for limiting organism concentrations in ballast water.

Keever said the EPA is not setting the bar as high as it should. 

“We’re still basically at the same place we were at 20 years ago,” Keever said. “The EPA has never set what we see as the best available technology for ballast water discharges.”

More than 150 environmental groups made similar claims in a 2022 letter to President Joe Biden, arguing that the technology exists now to almost entirely sterilize ballast water. 

“[W]e have the technical ability to efficiently remove or kill organisms that are trapped in a tank of water,” they wrote. “For half a century federal law has required EPA to use that ability to protect the environment and public health — yet EPA still refuses to do so.”

The EPA disagrees with the criticism. Joshua Alexander, press officer with the agency’s Region 9 San Francisco office, told CalMatters that “the EPA concluded that these standards (in the new rules) are the most stringent ones that the available ballast water test data can support.”

Can anything stop the mussel invasion?

October’s discovery of the golden mussel in California is being treated urgently by state and federal officials.

The creatures have wreaked havoc on water supply and hydroelectric facilities in South America, and they are spreading rapidly through central China. In the Great Lakes, invasive zebra mussels cause $300 to $500 million in damages annually to power plants and other water infrastructure — the types of impacts officials in California hope to avoid. 

Tanya Veldhuizen, the Department of Water Resources’ special projects section manager, said officials are considering the use of chemicals to remove the creatures from pumps, intakes and pipelines of the massive State Water Project, which transports water to farms and cities.  

Several scientists told CalMatters that with most nonnative species, eradication is only possible early in the game — meaning management officials often have one shot at success.

Biologist Andrew Chang, who works at the Smithsonian research center’s Marin County field lab, noted an old adage in invasion ecology — containing the spread of a nonnative species is like trying to put toothpaste back into a tube. “The more time that passes, the process of putting the toothpaste back in the tube gets messier and messier,” Chang said.

University of Windsor’s MacIsaac thinks California may be on the cusp of an unstoppable mussel invasion. 

“This is an enormous problem for your state,” he said.