Santa Monica beachgoers may notice pink waves over the next two weeks, but officials stress there is no need for concern. It is the work of the non-toxic dye used by University of California, Los Angeles (UCLA) scientists and the Bay Foundation to study how ocean movement affects the long-standing issue of poor water quality.
The project is part of a broader effort to understand how pollution spreads along Los Angeles County’s coast and to develop strategies to make local beaches cleaner and safer for swimmers. Researchers hope the experiment will give scientists and city leaders new insights into how currents and tides influence water quality near one of California’s most popular beaches.
The first round of dye was deployed on Monday morning near the Santa Monica Pier, which consistently ranks among California’s dirtiest beaches despite city efforts to improve conditions. For years, Santa Monica has struggled with stormwater runoff, bacterial buildup and debris from nearby urban areas entering the ocean. These issues worsen after rainstorms, when pollutants from the city streets are washed directly into the bay.
Researchers say the temporary coloring, known as rhodamine water tracer dye, will help track how currents move pollutants around the bay. The dye, which is fluorescent pink, has been used in environmental studies across the world and is safe for marine life and the public.
“By tracking where the dye goes, we’ll get a better idea of how the breakwater affects the environment around it, which will help us understand why Santa Monica beach has such bad water quality,” said Isabella Arzeno-Soltero, an assistant professor of civil and environmental engineering at UCLA.
“It was a big success today,” said UCLA doctoral candidate Gabriela Carr, who contributed to the project. “It’s pink—the dye—but it’s also fluorescent, so that’s pretty much our principal tracker.”
The study focused on the Santa Monica breakwater, a rocky structure built in the 1930s for a marina that was never completed. Though damaged over time, the structure still alters wave patterns and water circulation in ways that may trap pollutants near the pier. Scientists believe limited water flow around the breakwater could be a major factor behind Santa Monica’s persistent pollution issues, and removing or modifying the structure could improve circulation.
City leaders hope the research will provide solutions to Santa Monica’s longstanding pollution challenges. They believe understanding how water moves around the breakwater will help guide future environmental projects.
“We’re trying to see if the circulation of the water is so poor that it is creating the concentrated pollution 100 yards north and south of the pier. We don’t want to keep ending up on the beach.”
Said Mayor Lana Negrete, who attended the first dye deployment.
Santa Monica has already invested in stormwater capture systems, advanced water treatment and dune restoration. Negrete emphasized that this new study is one of several initiatives aimed at restoring water quality.
The next surface-level dye release was scheduled for Sept. 22-24, with the final underwater deployment planned for Sept. 30. Officials expect preliminary results by mid-October and hope the date will guide future coastal management policies, ensuring Santa Monica’s waters become cleaner for both residents and tourists.