Anytime it rains, a river of trash flows straight toward the ocean, spitting out at the mouth of the San Gabriel River.
The area between Long Beach and Seal Beach has long been a trouble spot as pollution from urban inland cities flows down the river and onto the beach and into the ocean where Orange County and Los Angeles County meet.
Seal Beach city officials have taken a key step to finding a solution, they said, voting this week to move forward with a memorandum of understanding with Los Angeles County to tackle the trash troubles.
At the same time, a consultant has finished a report exploring options and technologies, including cost estimates for innovative solutions.
Shane Silsby, CEO of Stantec Consulting Services Inc., detailed for council members at their recent meeting some of the area’s challenges and ideas that could help stop the trash before it flows down to the ocean.
In 2024, Councilmember Joe Kalmick and Assemblymember Diane Dixon joined forces to create a working group, hosting meetings about the issue, with a number of environmental groups and other cities joining the discussion.
The Stantec report says the amount of trash found at the shore has been trending upward in recent years. In 2021, an estimated 330 tons were reported, and by 2024, 461 tons of trash had to be removed.
The report, which also involved The Ocean Cleanup, a nonprofit that specializes in finding ocean trash solutions, identified several locations that could benefit from the adoption of various technologies, each ranked based on feasibility.
Ideas included installing screens at inlets, such as open channels, to stop trash from flowing, floating booms to corral trash, trash wheels and trash interceptor technologies.
Each trash mitigation location and device type evaluated was scored based on several criteria, including expected trash volume at the location, trash capture ability of the device, implementation complexity, operation and maintenance level of effort, land use considerations and environmental factors.
The use of trash interceptors with floating booms got the highest scores and would work best if placed between East 7th and 2nd streets and south of the 405 Freeway, the consultants said, however the lower height of the bridges in those areas could be an issue.
The trash interceptor, however, is also the most expensive option, according to their report. The estimated cost to install one could be $4 million to $7 million, with an annual maintenance and operating cost of $400,000 to $750,000.
The next best option would be the placement of floating booms and manual trash removal from the adjacent riverbank using an excavator or crane with a clamshell bucket.
Just the floating booms can cost anywhere from $2 million to $3.5 million.
Screens to prevent the trash from entering the system, on the other hand, range from $5,000 to $25,000, with annual maintenance costs between $50,000 to $75,000.
The study analyzed the pros and cons of each system and helped identify grants and funding sources that could become available.
The study also addresses issues such as environmental considerations, with extensive discussion around the sea turtles that call this waterway home. Meetings were held with the Aquarium of the Pacific, which has a program that rehabilitates and releases sea turtles in the area, Silsby said.
Efforts would be done with The Ocean Cleanup, Silsby said. And, Los Angeles County officials, if they sign the MOU, would agree to fund the operation and maintenance of the project, he said. The river runs through much of the county.
“The city of Seal Beach gets a project delivered to them at no material cost,” he said. “The expected benefits are cleaner beaches, protection of marine life, reduced maintenance costs, better water quality and more engagement with the community.”
Councilmember Patty Senecal said she was surprised to learn that trash doesn’t just go out to the ocean, but rather cycles back for several weeks with the tides, washing up and back out again.
“During those three weeks of trash in, trash out, people don’t want to use the beach, allow their kids in it or surf in it,” she said of the time after rainstorms. “You don’t know what’s out there and how much.”
“This is a great thing for us to be doing,” she said.
Senecal added she’s appreciative of the city’s maintenance crews and all the volunteers who regularly pick up the trash strewn on the beach.
Mayor Lisa Landau said she wondered if there would be participation from the other 60 cities that line the river’s inland watershed to help remove the trash before it washes to Seal Beach.
The watershed spans about 713 square miles across Los Angeles and Orange counties, draining a mix of urban, suburban, and open space land uses. The river runs roughly 75 miles from its headwaters in the San Gabriel Mountains to its outlet at the Pacific Ocean between the cities of Long Beach and Seal Beach.
There’s no mechanism now for asking other cities to pay their fair share, because costs are unknown and it is also unknown exactly where trash comes from, Silsby said.
The study identified some key contributors: urban runoff, freeway corridors, illegal dumping and encampments located near the river channel.
The consultant group is working with The Ocean Cleanup to install cameras with advanced technology at various locations, using AI to analyze volumes and materials, like whether the detritus is debris or plastics, to try and predict where it is coming from, Silsby said.