By Jorge Casuso

September 16, 2025 -- The water around the Pier is among the most polluted on the West Coast, and on Monday it turned pink.

The change had nothing to do with increased bacteria, but the pink dye could help scientists understand the water movements that contribute to a problem the City has spent millions of dollars to correct.

"The water containing the dye will carry the passive tracer wherever the current leads," said researchers from the UCLA Samueli School of Engineering, which is conducting the study funded by The Bay Foundation.

After releasing the "fluorescent rhodamine water tracer dye" near the breakwater, researchers will use monitors to track the temporary non-toxic dye that naturally disperses, having no impact on the ecosystem, researchers said.

Pink dye released into the water near the pier Monday
(Courtesy UCLA Coastal Flood Lab)

A major cause of the persistently high bacteria levels that prompts public health officials to consistently issue water quality advisories for the Pier is a breakwater constructed in 1934.

The remnants of the breakwater used to create what was once the Santa Monica Yacht Harbor have been damaged by decades of storms that have reduced it to a sliver of rocks that can still be seen during low tide.

“Although the breakwater was badly damaged and the elevation reduced, it still substantially impacts the coastal hydrodynamics and surrounding environment,” said Timu Gallien, an associate professor of engineering at UCLA Samueli who is the study’s principal investigator.

“For example, the breakwater protects the beach from large waves, keeping the beach wider that it would naturally be.”

Assistant professor Isabella Arzeno-Soltero, the study’s co-investigator, said that "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.”

In Heal the Bay's latest annual report released in May, the Pier was ranked as the second most polluted beach on the West Coast, topped only by Mexico's Playa Blanca, a beach contaminated by untreated sewage from the Tijuana region.

Nearly every year, the Pier receives F grades for water quality and consistently ranks near the top of Heal the Bay's notorious Beach Bummer list.

The Pier's consistent raking among the West Coast's most polluted beaches is largely due to debris from an estimated 10 million visitors a year, fecal matter from birds and its proximity to the Pico Kentor storm drain, which receives runoff that carries bacteria.

Over the past seven years, the City has spent more than $100 million to protect Santa Monica Bay and improve beach water quality by implementing measures that include upgrading stormwater capture systems and installing bird deterrent netting.

In its 2024-25 annual report, Heal the Bay noted that "inconsistent maintenance of the netting and urban runoff from the Pier remains a challenge," the report said.

"The limited effectiveness of current measures highlights the need for increased mediation," the report said.

City officials have noted that the Pier area included in the Beach Bummer listing encompasses only the ocean water 100 yards north and south of the Pier along the beach's 3-mile coastline.

The current project builds on a 2024 experiment by the UCLA Coastal Flood Lab and The Bay Foundation, "continuing efforts to study how the Santa Monica Breakwater influences ocean circulation and contributes to poor water quality."

The dye releases have been reviewed and approved by the city of Santa Monica, the California Coastal Commission and the U.S. Army Corps of Engineers.

Researchers were at the site during the experiments to share informational brochures and answer questions from the community.