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No BS Visits the South Bay International Water Treatment Plant

Scrubbers, Scum Skimmers, and Cake.

These are the buzzwords that float (no pun intended) around the South Bay International Water Treatment Plant (SBIWTP).  

 On Saturday, May 30, 2015, the Surfrider Foundation San Diego County Chapter’s No Border Sewage Program (No BS) took 12 of its dedicated volunteers to the SBIWTP for a tour.  Steve Smullen, Area Operations Manager for the San Diego office of the International Boundary and Water Commission, graciously spent his Saturday morning talking to us about the facility and its role in the border sewage issue.

 We began our day in their conference room, inspecting a bird’s eye view photograph of the Tijuana San Diego area west of the San Ysidro Port of Entry and the numerous underground pipelines running to and from the many facilities within the vicinity - wastewater treatment plants, pump stations, and reclamation plants on both sides of the California/Mexico border. This vicinity also includes the South Bay Ocean Outfall, a pipe 11 feet in diameter and 19,000 feet long that extends into the Pacific Ocean and discharges treated wastewater after it leaves the SBIWTP.


As Steve led us through the facility grounds we saw many pumps, tanks, filters and other machinery.  He explained how there is a logical order to the plant’s layout. First, wastewater from Tijuana enters the treatment plant. As this happens, large particles and debris, sticks and rags, are removed with a screen and conveyor-belt-style contraption.  The water is then pumped into a series of settling tanks where primary solids are allowed to either settle at the bottom of the tank or float to the top where skimmers are used to scrape and dispose of them.  The wastewater is then sent to aeration basins where bacterial activity degrades pollutants further. This creates some additional solids, so the wastewater is resettled. Settled solids are removed by pumping, dewatered with filter presses, treated with quicklime and hauled to Mexico for disposal.


The tour was extremely interesting and informational - and Steve was on point answering all of the questions our volunteers could throw at him.  The mission of the No BS program is to eliminate trash, sediment, sewage and chemicals from entering our oceans - thus, our questions followed suite.  Why is the water so dirty to begin with? What causes overflows into the river? And what else can we do to help solve some of these issues?


So, why is the water so dirty to begin with?

As Steve explained, the Arturo Herrera and La Morita Wastewater Treatment Plants in Tijuana, produce treated water that is actually cleaner than the water produced at the SBIWTP.  The effluent from those treatment facilities is discharged to the Tijuana River. While there, it picks up more debris, sediment and sewage until it is removed from the river by the CILA Pump Station before entering the US. The CILA Pump Station conveys this water to the coast in Mexico where is discharged. .

What causes overflows into the river?

Many people are unaware that Tijuana does not have separate sewage and storm drain systems.  (View a Map of Tijuana’s Wastewater System here.)  When rain falls, their sewage system is surcharged and the CILA Pump Station’s screens get clogged. They cannot be cleaned and the pump station is unable to handle the large influx of water and sediment.  Because of this, the pumps are turned off until the flow in the river becomes low enough to clean their screens, remove sediment and manage the water again.

And what can we do to help solve some of these issues?

We urge you to stay educated on the issues, and spread the word.  Tell your friends and family how the trash, sediment and sewage in the Tijuana River often flows into the Pacific Ocean and causes beach closures in the South Bay Area.

Reach out to decision makers and politicians in your community and let them know where you stand on the issues.

And finally, volunteer!  Come to a cleanup or other event to get hands-on experience and be part of the change.  Don’t want to get dirty?  That’s ok too - there are plenty of other volunteer opportunities in a wide variety of tasks in the No BS program.

To bring our tour to a close, we stopped off at Wild Willow Farm & Education Center, a 6-acre working farm in the Tijuana River Valley. Wild Willow graciously hosted us for lunch and a tour of their beautiful grounds.  We look forward to revisiting farm Director Mel Lions and his crew to learn more about their San Diego Roots Sustainable Food Project later this year.

Read more about the Surfrider Foundation San Diego County’s No Border Sewage Program at, or email us at to get involved.