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The South Bay International Wastewater Treatment Plant (SBIWTP)

What’s the most well-known problem that effects the U.S.-Mexico border between Tijuana and San Diego?

I can tell you in one word: SEWAGE

In 1887 Hart & Stern created the city of Tia Juana, which existed on both sides of the border at approximately the location of the San Ysidro Port of Entry. In 1891, however, a flood washed the city away. Most residents fled to 300 feet above sea level on exclusively the Mexican side in what today we know as the city of Tijuana.

Tijuana currently sits on a watershed and when rains hit the region, the sewage system capacity is exceeded and sewage flows downward into the flood plain and the Tijuana River Valley located on the U.S. side.

The issue of Tijuana sewage contaminating U.S. water supplies has existed at least since 1934 when the International Boundary Commission created a report on the problem. Here’s a fairly comprehensive history written by the International Boundary & Water Commission (IBWC).


Established in 1889, the IBWC is a small international organization that manages both the boundary monuments and the water rights along the U.S.-Mexico border. Their headquarters are in Texas and they have about 250 employees total.

Steve Smullen, Area Operations Manager, has worked in San Diego for seven years. An agricultural engineer who graduated from the University of Idaho, he  kindly gave me a tour of the IBWC’s Sanitation Plant, which was finished in 1997 with the intent of solving the wastewater & sewage problem between Tijuana and San Diego. The plant was built on a 75-acre sit at the international boundary and in the Tijuana River Valley where ranchers and farmers used to grow crops.

So what happened? Population growth, for one thing. Tijuana continues to grow and currently has a population of 1.6 million people. The city doesn’t have the funds to create the appropriate infrastructure, so as the city continues to grow, the sewage problem persists.

Nevertheless, the IBWC staff is able to provide treatment of 25 million gallons per day. Perhaps it’s not enough, but it’s also pretty darn impressive.


Steve Smullen gave me a fascinating tour of the South Bay International Wastewater Treatment Plant (SBIWTP), which I immediately realized came along with three facts:

1) It’s smelly. It is, after all, sewage. I would highly recommend you not chose this place for your birthday parties.

2) SBIWTP treats the sewage and then sends thebiosolids back to Mexico and the liquid wastes into the “outfall” to the Pacific Ocean. In the future, this could become recycled water for irrigating or even for drinking if the public would vote for a higher strength purification process, but for now this plant is solely focused on treating the sewage so that it does not contaminate our environment.

3) Finally, this sanitation treatment facility is not to be confused with the one right next door, the South Bay Water Reclamation Plant, which also sanitizes water and sends it out to the Pacific Ocean. Why is this important? Because Imperial Beach council member, Ed Spriggs, has brought to light that the South Bay has dual “outflow” going into the ocean area of the South Bay. That is, this treatment plant and the one adjacent to it both pour treated waste out into this neck of the ocean.

So ready for the stinky? I mean for the skinny? Tomorrow I’ll show you how this treatment facility works.

Address: 2225 Dairy Mart Road, San Ysidro

(See Part 2 of this story.)

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