Aerial view of sewage water spilling into Playa Blanca beach in the coast of Tijuana, Baja California state, Mexico on March 21, 2024. Tijuana's recreational beaches are among the most polluted in the northern coast of Mexico. (Photo by Guillermo Arias / AFP) (Photo by GUILLERMO ARIAS/AFP via Getty Images)
San Diego, California – A 1,000-foot-long floating trash boom, quietly installed just north of the U.S.-Mexico border last November, has intercepted over 500 tons of waste before it could reach California’s coast. For decades, the Tijuana River has carried trash and debris across the border during storms and flood events, fouling the Pacific Ocean and wetlands in San Diego County. But this new binational project may signal a shift in both approach and outcome.
Led by the nonprofit Alter Terra in collaboration with the Rural Community Assistance Corporation (RCAC), and supported by the U.S. Section of the International Boundary and Water Commission, the boom was designed to respond to the river’s volatile flows. In March, when a storm pushed water levels to nearly 13,000 cubic feet per second, the 1,200-foot structure — anchored by 360 feet of reinforced rigging — held firm.
“We controlled 100 percent of the trash that flowed across the border,” said Oscar Romo, executive director of Alter Terra. Romo, a longtime advocate for watershed resilience, credits the boom’s adaptive engineering and strategic placement. Suspended just above the riverbed, the structure rises and falls with the waterline, intercepting floating debris while letting sediment-laden water pass beneath.
That detail matters. Sediment continues to reach the U.S. side, largely due to unregulated dumping from construction sites in Tijuana. But drone surveys of the floodplain show a dramatic drop in trash accumulation across key collection zones. Gone are the piles of tires, plastic, and discarded furniture that once littered the estuary.
By volume, the captured debris is mostly plastics and Styrofoam — 41% and 25%, respectively — while heavier waste like organic trimmings and construction wood account for most of the total weight. The waste reflects a blend of everyday household refuse, illegal dumping, and runoff from densely populated upstream communities. Alongside cleanup, the boom is offering researchers new insight into the sources and patterns of pollution throughout the watershed.
Later this year, Alter Terra plans to temporarily remove parts of the boom to grade the riverbed and clear sediment and vegetation buildup. Afterward, the system will be reinstalled and potentially expanded. Already, other municipalities are paying attention — including Los Angeles, which is considering a similar approach to help manage waste in the L.A. River.
For now, the pilot project continues, supported by binational partnerships and field data. What was once seen as an intractable environmental problem is beginning to show signs of movement — not just in the water, but in the will to change what flows downstream.
