Air Date: Week of September 9, 1994

San Diego County, California has experienced beach closings due to raw sewage outflow from Mexico. Reporter Bebe Crouse visits a prototype sewage plant which treats sewage as a resource rather than a problem. It's being offered as an alternative to a massive treatment plant, towards which the US Government is contributing half a billion dollars.

Transcript

CURWOOD: San Diego County in California has been plagued in recent years with beach closings stemming from untreated sewage that flows north from neighboring Tijuana, Mexico. US officials are working with their Mexican counterparts to build a massive sewage treatment plant to address the problem, but as Bebe Crouse reports from Mexico, there may be a more effective and more affordable way.

CROUSE: It's a brilliant blue sky day at Imperial Beach, a long stretch of sand just north of the Mexican border. But despite the weather, the beach is virtually empty. That's because the ocean here is unfit for swimming due to colIform contamination. Dave Schlesinger is director of San Diego's Metropolitan Waste Water Department.

SCHLESINGER: Last year, the summer of 1993, the beaches were quarantined for over 200 days, and now this is a major impact upon the tourism, the business of the coastal beach cities. But even more important than that, it's a health issue.

(Sound of running water and traffic)

CROUSE: Part of the problem is simply geography. At the boundary between Tijuana and San Diego, a broad coastal plain rises up into steep hills on the Mexican side. The water from those hills drains into the Tijuana River, which, oblivious to fences and customs agents, reaches the ocean on the US side of the border. And since perhaps 50% of the homes in Tijuana are not connected to sewers, much of what the river brings north is raw sewage.

JACOBS: This is Stewarts Drain, and this is what we call Stewarts Bridge, and this is a natural drainage from Mexico into the US. So when it rains...

CROUSE: Chuck Jacobs is an engineer with the International Boundary and Water Commission, the IBWC. And what he's pointing to is a stream of murky water flowing from beneath a busy street that skirts the Tijuana side of the international border. As the smelly rivulet dumps into the US, it's channeled toward a concrete pipe.

JACOBS: This pipe does not come to the US; it goes toward Mexico. This is one of our defensive works areas, and we collect the sewage, the minimal renegade flows that come across here.

CROUSE: Through a system of pipes and pumps, the IBWC tries to capture this so-called renegade sewage and send it back south to a Mexican sewage treatment plant. But that plant often operates at capacity. And when it rains, both it and the IBWC'S elaborate defenses break down and raw sewage spills into US waters. After years of haggling over the problem, both countries agreed to build a binational sewage treatment plant on the US side of the border, with an ocean outfall off the San Diego coast. And though it's still unclear how much Mexico will chip in, the US share of the project cost is nearly half a billion dollars.

DE LA PARRA: Government thinks that throwing money will be the solution to pollution.

CROUSE: Tijuana-based engineer Carlos De La Parra thinks that money could be better spent. For a fraction of what the big binational plant will cost, De La Parra's team has built a small scale alternative plant that not only treats Tijuana sewage but has the added benefit of reclaiming the water and using it to irrigate the city's drought-plagued hillsides.

(Sound of water sprinklers)

CROUSE: Instead of a centralized system in which sewage is pumped for miles, and at considerable cost, to a massive treatment plant, De La Parra advocates a series of smaller, less costly local plants like this prototype.

DE LA PARRA: This is raw sewage coming in.

CROUSE: This is a passive system of filters and clarifiers with virtually no moving parts and hardly any need for maintenance.

DE LA PARRA: It's very low technology. This is very low energy. Low cost. Reliability. This has never broken down in 2 years of operation. We must be breaking a record in terms of wastewater treatment plants in developing nations.

CROUSE: Aside from claiming the treated water, solid waste is composted and used at a small greenhouse and nursery on the site. And plans don't stop there.

(Footfalls on gravel, birdsong)

DE LA PARRA: These are the future wetlands.

CROUSE: Artificial wetlands will further cleanse the water to a level that De La Parra hopes will make it safe enough for swimming and showering. At the very least, the water could help reforest the barren city and stop severe erosion.

DE LA PARRA: The key question is, right at the start, is sewage a problem or is it a resource?

CROUSE: So far, the people dealing with Tijuana's sewage see it only as a problem. Washington and Mexico City have rejected the idea of reclamation as too expensive. But they're only looking at part of the balance sheet. It's the city of Tijuana that has to buy the water in this parched region, and De La Parra says they see the project differently.

DE LA PARRA: Because they have to pay the state to use the water to irrigate the urban greenery in the city. We can sell the water at half the price. That attracts their attention.

CROUSE: Calls to the city went unreturned but De La Parra says Tijuana's mayor has agreed to buy some of his reclaimed water. In a city whose population has quadrupled in a little more than a decade, the demand for both water and sewage treatment will only increase. And in time, De La Parra believes the city and Mexican government will come to see these small plants as a logical way to meet both those demands and help solve a problem with its neighbors in San Diego. For Living on Earth, this is Bebe Crouse in Tijuana, Mexico.