Santa Monica’s waves have turned a bright pink. How can the dye job improve water quality?
-
Click here to listen to this article - Share via
See more from the L.A. Times in Google Search. Set us as preferred
- Bright pink dye released into Santa Monica Bay over the next two weeks will help researchers study how circulation could be affecting water quality.
- Santa Monica Pier routinely ranks among California’s dirtiest beaches despite ongoing city efforts to improve water conditions.
Over the next two weeks, surfers and beachgoers in Santa Monica may spot waves that have a pink, fluorescent hue — but officials say not to worry.
The luminous, pink color spreading across the Santa Monica Bay is from a temporary, nontoxic dye that researchers are using to study how ocean circulation might contribute to the bay’s poor water quality.
The project kicked off Monday morning, as researchers with UCLA and the Bay Foundation discharged the first of four batches of the pink dye near the Santa Monica Pier.
For the record:
4:37 p.m. Sept. 15, 2025An earlier version of this article referred to Heal the Bay being involved in the project. The organization is the Bay Foundation.
“By following where the dye goes, we will better understand how the breakwater changes the environment around it, providing insight into Santa Monica beach’s poor water quality,” Isabella Arzeno-Soltero, an assistant professor of civil and environmental engineering at UCLA and a researcher on the project, said in a statement.
Although the pink dye on Monday didn’t appear to create many “bright pink waves,” as researchers warned might be the case, additional bouts of the fluorescent rhodamine water tracer dye will be released later this month.
For decades, surf camps and schools have been a mainstay of local beaches across Santa Monica Bay, but concerns over pollutants from the Palisades fire are hurting business.
But the fact that the dye seemed to dissipate quickly Monday didn’t mean the first phase won’t lead to important data, said Gabriela Carr, a researcher in the project and doctoral student at UCLA’s Samueli School of Engineering.
“It was a big success today,” Carr said. “The dye is pink but it’s also fluorescent, so that’s kind of our main tracker.”
A boat with “finely tuned fluorescent monitors” would remain in the bay for 24 hours, Carr said, and at least 10 additional trackers will remain attached to buoys through the end of the month, when additional dye drops will occur.
The study is intended to help researchers understand how the manmade breakwater that was built in the 1930s in Santa Monica Bay, often visible during low tide, might hurt water circulation and, therefore, water quality. Santa Monica Pier routinely tops the yearly list of the state’s dirtiest beaches by environmental nonprofit Heal the Bay, which tests waters up and down the California coast for fecal bacteria, which can harm beachgoers.
The break in the Santa Monica Bay was constructed to create a marina, but storms and time damaged it beyond effectiveness, though remnants of the rocky break still affect the water flow, researchers said.
A flock of brown pelicans was released back into the wild near the Huntington Beach Pier. They had been nursed back to health after being sickened by a toxic algal bloom.
“It still substantially impacts the coastal hydrodynamics and surrounding environment,” Timu Gallien, an associate professor of civil and environmental engineering at UCLA and a lead researcher in the study, said in a statement. “For example, the breakwater protects the beach from large waves, keeping the beach wider than it would naturally be.”
Santa Monica Mayor Lana Negrete watched the first deployment Monday morning and said she was hopeful this research could help her city finally get off the list of “beach bummers.” The city has partnered with the UCLA Samueli School of Engineering and the Bay Foundation on the project.
“We’re trying to see if the circulation of the water is so poor that that’s creating the concentrated pollution 100 yards north and south of the pier,” Negrete said. “We don’t want to keep ending up on the beach bummer list — it’s a bummer!”
She said this is one of many projects to help researchers understand and combat water quality issues, including a relatively new advanced water treatment facility and a sand dune restoration project.
“This is all working in tandem,” Negrete said. “The whole ecosystem is important.”
The researchers did not include in their announcement what remedies might be recommended if the breakwaters are determined to be responsible for, or a factor in, the poor water quality. That would probably be a multifaceted decision involving city and environmental leaders.
Heal the Bay has released its annual report card on California beaches. The dirtiest include one in L.A. County and four in San Diego County.
Although this is the first time the dye has been used in the Santa Monica Bay, UCLA researchers said the coloring has been used for many years in other waterways, explaining that it disperses naturally and poses no risk to people, animals or vegetation.
Carr said there may be more pink visible next week when the team performs another surface-level drop of the dye, but probably not as much when they do two deep-water drops later this month.
Still, the pinkifying of the bay might not be much of a spectacle despite signs that were plastered all around the Santa Monica Pier area that scream: “Why is the water pink?”
Carr said the team wanted to be sure the public did not become alarmed if the pink color was spotted.
The next surface-level dye deployment will occur sometime Sept. 22–24, and the last underwater deployment will be Sept. 30, Carr said.
More From the Los Angeles Times
Podcasts
Kim, an attorney and former San Francisco supervisor, is running against State Sen. Benjamin Allen for the role of running California’s long-beleaguered Department of Insurance. In this episode she talks to Rebuilding L.A. host Kate Cagle about why she should get the job.
The Hillside Strangler murders terrorized Los Angeles in the late 1970s. The killers were a pair of sadistic cousins. One confessed. The other was set to stand trial—until L.A. prosecutors flinched.
Hosts Fidel Martínez and Suzy Exposito sit down with Puerto Rican rapper and composer Álvaro Díaz, fresh off the release of OMAKASE — his third album, a genre-defying concept record that debuted at number one globally on Spotify and is charting in 16 Latin American countries.
