Water pollution is fueling ocean acidification. Environmentalists urge California to act

Welcome to today’s edition of Boiling Point. I’m Ian James, a reporter on The Times climate and environment team, filling in for my colleague Sammy Roth.

As the burning of fossil fuels and other human activities continue to increase the levels of carbon dioxide in the atmosphere, the ocean is absorbing a large portion of the CO2, which is making seawater more acidic.

The changing water chemistry in the ocean has far-reaching effects for plankton, shellfish and the entire marine food web.

And here’s one important fact about ocean acidification: It’s not happening at the same rate everywhere.

The California coast is one of the regions of the world where ocean acidification is occurring the fastest. And researchers have found that local sources of pollution are part of the problem.

In particular, effluent discharged from coastal sewage treatment plants, which has high nitrogen levels from human waste, has been shown to significantly contribute to ocean acidification off the Southern California coast. These nitrogen-filled discharges also periodically contribute to algae blooms, leading to hypoxia, or oxygen-deprived water that is inhospitable for marine life.

Environmental advocates are concerned that these discharges are taking a severe toll on the ecosystem, and are urging state leaders to take steps to improve wastewater treatment to clean up the pollution.

A man walks on the San Gabriel River jetty in Long Beach in 2019.

(Luis Sinco / Los Angeles Times)

In a letter to Gov. Gavin Newsom and other state officials, leaders of 29 organizations called on the state to “act immediately and decisively to protect our ocean from the alarming occurrence of ocean acidification off the California coast.”

“Ocean acidification is gradually shifting the California coastline toward a more acidic, corrosive state, while hypoxia — or low dissolved oxygen levels — is making the ocean less habitable for organisms ranging from sea snails to crabs to fish,” the conservation advocates wrote. “The science is clear that coastal sewage treatment plant discharges of nutrients to the ocean are linked to ocean acidification and the loss of oxygen.”

In other words, California doesn’t yet have a plan for addressing the problem, and research shows the problem is getting worse.

The coalition of environmental groups, led by the California Coastkeeper Alliance and Natural Resources Defense Council, urged state water regulators to develop a policy for addressing ocean acidification and hypoxia — or OAH — and to begin setting standards to require the removal of nutrients from treated effluent that wastewater plants discharge into the ocean. They said this and other steps, as well as state funds, are urgently needed to stop an impending “environmental disaster” and prevent hot spots of acidification and oxygen-starved waters from worsening along the California coast.

“It’s not just coming from global climate change. It’s also coming from our land-based sources of pollution. And we can address that,” said Sean Bothwell, executive director of the California Coastkeeper Alliance.

By requiring wastewater facilities to upgrade systems to remove nitrogen from the streams of treated wastewater, Bothwell said, “it could have a large impact on protecting these areas and not exacerbating the problems of climate change.”

Such upgrades at wastewater treatment plants are expected to be costly. But Bothwell and other clean water advocates say the adoption of standards and improvements in treatment should happen now, while Southern California water agencies are moving forward with plans to build large wastewater recycling facilities to bolster the region’s water supplies.

“Water recycling with nutrient reduction, which can make Southern California’s water supply more reliable, can also help clean up our ocean waters,” Bothwell said.

Mark Gold, director of water scarcity solutions for the Natural Resources Defense Council, said designing water recycling facilities that also clean up discharges from Southern California’s large coastal sewage treatment plants “can provide the dual benefits of drought proof, reliable water supplies and nutrient load reductions that will greatly slow the pace of ocean acidification and hypoxia.”

“We’re already seeing the impacts on ocean acidification and hypoxia off of the West Coast today. This is not something that’s 20, 30 years down the line,” Gold said. “Every year that goes by is just another year of coastal water degradation and impacts on marine life. And so really time is of the essence to move forward on this, so we can start getting progress in the right direction.”

The stakes are high for the health of the coastal environment. Scientists have been seeing alarming signs of worsening ecological effects. When they examine shells collected off the coast, they’ve been finding that some are thinner and pitted — showing that the hard calcium carbonate is increasingly dissolving.

These changes can be difficult for people to directly observe. But the science has shown that the shifts are harming sea life.

In their letter, the coalition of environmental advocates wrote that “shell-forming organisms including Dungeness crab larvae and oysters are having a tougher time building their shells, and fish are experiencing behavioral changes that make them more vulnerable to predation.”

They said California’s hot spots have acidified to a point that some plankton — tiny marine snails called pteropods — and Dungeness crab larvae can suffer “shell dissolution,” in which the water becomes so acidic that it causes shells to dissolve. And the conditions have also deteriorated to a point that northern anchovies “don’t have enough oxygen to thrive in large swaths of southern California’s coastal waters.”

The effects are most pronounced off Southern California during the warmest months of the year, from August through October, when discharges from wastewater plants contribute to the formation of hot spots of acidification and oxygen-deprived water.

Scientists describe one of the effects as “habitat compression,” in which conditions in some waters become uninhabitable — not “dead zones” that kill fish, as exist in some other regions, but rather “sublethal” conditions that cause stress for animals. This sort of degraded conditions will drive an animal to swim away, if it can.

Recent research has shown that during late summer, large portions of the waters off Southern California are rendered unsuitable for marine life. The areas with degraded habitats have been shown to reach, on average, 20% of the water vertically in about one-fourth of the area of the Southern California Bight — the curved coastline from Point Conception to the San Diego area — and extending up to 50 miles offshore.

Gold has been deeply involved in efforts to address ocean acidification and hypoxia for years. He previously served as Newsom’s deputy secretary for oceans and coastal policy and executive director of the Ocean Protection Council.

Gold said scientific research has expanded tremendously over the last decade and has revealed that the scale of the problem is far larger than had been predicted.

“This isn’t just near shore. This is to 50 miles offshore, the other side of the Channel Islands,” Gold said.

Gold had initially expected research would demonstrate that increasing CO2 levels in the atmosphere were the dominant driver of acidification and hypoxia. But he said he has been surprised by the growing body of research showing that nutrient-laden water released by sewage treatment plants is having a significant effect.

“What we see here in Southern California,” he said, “is greatly exacerbated by the discharges from the large sewage treatment plants.”

In one recent study, scientists at the Southern California Coastal Water Research Project and UCLA used a model to estimate how reductions in nitrogen from wastewater treatment facilities would affect the changes in seawater and habitats, and found that algae formation, acidification and oxygen loss would decline progressively with reductions in nitrogen, while habitats would improve.

The latest findings point to a need for the state to move quickly, Gold said.

“We have water quality conditions that are acidifying, and we’re seeing low oxygen, and it’s covering an area far larger than anyone would have predicted. And so it’s important for the state to pull together all of this information and come up with management recommendations to slow the pace of degradation as soon as possible,” Gold said.

The scale of the problem, he said, is “larger than any impact I’ve seen on local coastal waters in my 35 years of working on ocean issues.”

People walk along the shore in Seal Beach in 2022.

(Gary Coronado / Los Angeles Times)

In response, state officials said they are advancing efforts to protect coastal waters.

Jenn Eckerle, deputy secretary for oceans and coastal policy at the California Natural Resources Agency, said ocean acidification and hypoxia “present serious threats to California’s coastal and marine ecosystems and the coastal communities and economies that rely on them.”

Eckerle, who is also executive director of the Ocean Protection Council, said the council is supporting the development of policies through investments in modeling and monitoring to better understand the effects and potential responses.

“The State of California is committed to addressing land-based nutrient pollution,” Eckerle said in an email. She said the Ocean Protection Council’s officials are in “active discussions” with the State Water Resources Control Board about “potential management measures to address this issue.”

The environmental advocates said in their letter that the state water board has recognized the need to set water quality standards to prevent acidification hot spots, but has “made minimal progress due to insufficient resources.”

They urged state leaders to budget $2.8 million and set a deadline for the state water board to develop a water quality goal.

The state water board has said developing a policy for addressing ocean acidification and hypoxia is one of the agency’s top priorities this year.

“Our take on it is we’re very concerned,” said Karen Mogus, the state water board’s chief deputy director. “It is important, and we have a role in setting policy that will help to alleviate the problem.”

Mogus said that with the model-based research in Southern California indicating discharges from wastewater plants are significant contributors, “we have knobs that we can turn to control sources through our regulatory programs.”

This can be done through an amendment to the state’s ocean water quality plan limiting the levels of nitrogen in discharges, Mogus said, and the agency is in an initial stage of “scoping possible options for what those standards would look like.”

Developing a standard would involve a lengthy public process and the eventual adoption of regulations by the state water board. The U.S. Environmental Protection Agency would also have a role in approving the new standards under the federal Clean Water Act.

“This one is going to be very controversial, because what it could mean is very expensive upgrades to wastewater treatment plants,” Mogus said.

She said state regulators also plan to gather information about the feasibility of treatment processes.

The development of advanced water recycling plants wouldn’t necessarily eliminate the problem, because plants still would need to dispose of highly concentrated brine.

“There’s quite a bit of technical investigation that needs to go along with this, so that we can put in place a policy that is feasible and based on the current technologies that are available,” Mogus said.

Bothwell, Gold and other environmental advocates are urging state regulators to expedite their efforts to determine what level of treatment is needed to protect marine life and to adopt regulations to meet that goal.

The coalition of environmental groups — which also includes Heal the Bay, Los Angeles Waterkeeper and the Sierra Club — said in their letter that given the coast’s vital importance to Californians, “now is the time for bold, decisive action.”

They said in addition to cleaning up coastal pollution, efforts to curb carbon emissions are essential.

“Hopefully, we can get a handle on climate change, and we can come up with other ways to address acidification internationally,” Bothwell said. “But at the very least, I think what we can do is buy ourselves time, particularly off our coast, to make it not worse than the rest of the ocean.”

This is the latest edition of Boiling Point, an email newsletter about climate change and the environment in California and the American West. You can sign up for Boiling Point here. And for more climate and environment news, follow @ByIanJames and @Sammy_Roth on X.