Project Tackles Toxic River Flowing Into U.S.

Beside a patch of plywood shacks south of downtown, a pipe disgorges a steady stream of raw sewage into a channel already brimming with waste.

The foul soup flows on into the New River, which swells further with waste picked up from shanty towns and businesses along its course north through town and into the United States. As it pours through a 35-foot gap in the border fence into Calexico, the river is pea green, swirling with dirty suds and incapable of sustaining much of anything beyond the lowest worm.

Long an ecological basket case and diplomatic headache, the waterway is the focus of a new effort by the United States and Mexico to halt chronic sewage spills in Mexicali that send as much as 25 million gallons a day across the border. The North American Development Bank, which finances improvements in drinking water, sewer and waste disposal systems along the border, recently announced that it is chipping in $20.6 million to cover more than a third of the cost of a citywide sewer overhaul during the next four years. That overhaul includes construction of a new treatment plant, expansion of another and replacement of 19 miles of crumbling sewer arteries.

No one is promising a complete answer to pollution in the New River. But authorities on both sides of the border are optimistic that the project will improve the health of the river.

“The goal is that no water arrives at the border without treatment,” said Luis Manuel Venegas, who heads special projects for the Baja California state agency that builds sewers and supplies drinking water in Mexicali.

The bacteria-laden sewage that flows across the border has for decades been a blight on Calexico, where impatient local leaders have begun calling for the New River to be enclosed inside a huge pipe to contain the stench as it winds through town. Skeptics say they have heard government pledges to solve the problem in years past but with few tangible results.

“I’ve crossed this New River for 28 years, and I’m tired of this. I think Calexico deserves to have a nice backyard,” said Luis Estrada, who works next to the river as supervisor of Calexico’s treatment plant and airport manager. He is pushing to put the waterway inside a pipe. “It’s time to start acting.”

Concerns north of the border over possible health threats have gained urgency as the flow of undocumented immigrants increases through the Imperial Valley. Many immigrants are using the river to sneak across the border, wading chest-deep in the foam to evade U.S. agents who won’t set foot in the mess.

Although no one has studied whether the migrants get sick, experts say a few drops of the polluted water can prompt a skin rash. To avoid the risk of contaminating others, immigrants arrested after being in the river are returned immediately across the border without going to the Border Patrol station for processing.

During the past two years, officials in Mexicali on their own have enclosed portions of the river closest to the border. The new $57-million joint sewer project is considered crucial as the city, with more than 170 foreign-owned assembly plants, grows as a hub for manufacturing and trade.

Some of the sewer construction is already underway. A new pumping station is close to completion next to the plywood-shack cluster south of downtown and one day will pump sewage through a new main to the planned treatment plant.

The installation of pipes and connections in this part of town will end the constant dumping of waste--a problem mirrored throughout Mexicali as the population has rocketed to nearly 800,000, overwhelming a creaky system that doesn’t even reach some of the newest colonias. The new projects are in addition to nearly $8 million already spent by the two countries on “quick fixes” to ailing sections since 1995.

As part of the binational effort, U.S. specialists are accompanying Mexican counterparts during monthly checks of the river near industrial sites, pumping plants and treatment lagoons around Mexicali. The cooperation reflects what one Calexico official said has been a “change in attitude” on the part of Mexican officials, who are more prone to repair broken pipes quickly. The development bank held out on providing the money--which comes from the U.S. government--for the fix-ups until Mexican sewer officials agreed to charge higher rates to pay for improved maintenance.

Much of the planned work is aimed at making up for what Victor Miramontes, the bank’s managing director, calls “25 to 30 years of inaction” in running the sewer system.

Just how that neglect has affected health is unclear. Studies have found unhealthful levels of bacteria and chemicals on the U.S. side, but Imperial County officials report no known outbreaks of disease. They note that the river’s notoriety and throat-catching stench keep local residents out. A recent federal study warned against eating fish caught miles from the border in Imperial County because of risks from a handful of chemicals, such as PCBs and mercury.

There is little chance of catching fish at the border--the dirtiest point. Monthly checks there by state engineers, who dip buckets while clad in white safety suits, two layers of gloves and face masks, consistently find the river nearly bereft of oxygen. A school of tilapia swimming in the channel where the Calexico treatment plant empties into the river not far away won’t enter the river; at top speed, they turn back as if hitting a glass wall.

“Very few things survive,” said state water resources engineer Jose Angel, looking over the river as bits of trash floated past.

No one imagines that shoring up Mexicali’s sewers will turn the New River pristine--or even close. Even before it arrives in Mexicali, the river carries pesticides and other wastes that run off the vast farms of the Mexicali Valley. “We’re not talking about a real river,” said Venegas.

The city’s fast growth rate means the system will be at capacity again within five years of the completion of the planned projects.

On top of the capacity shortage remains the problem of curbing illegal dumping of waste oil, solvents and other chemicals that make their way into the river from backyard shops and businesses. Only the most advanced factories are equipped to remove contaminants before washing wastes into the sewers. Environmental officials in the United States have begun talks with Mexican counterparts on how to expand so-called pre-treatment.

“Once we get these big pieces, other things become possible,” said Eugenia McNaughton, a scientist for the U.S. Environmental Protection Agency who has worked closely on the Mexicali projects. “It’s slow work.”

Helping the river in Mexico won’t improve it much miles downstream, where it is fed mainly by runoff from Imperial County farmland before arriving at the troubled Salton Sea 35 miles north of the border. Mexicali sewage accounts for 10% to 15% of what finally pours into the polluted lake, which itself is the focus of a sweeping rescue project. (A project to clean the New River near Brawley will use artificial marshes to filter out contaminants.)

Plugging Mexicali’s leaks, say environmental officials, may help persuade reluctant farmers on the U.S. side to shoulder their share of the river cleanup.

The growing thirst for water in Mexico could someday mean that the New River--an accident of turn-of-the-century engineering--no longer crosses the border. Among the ideas being mulled for the long term is to clean the river sufficiently for watering crops and using all that water in Mexico. That would dry up the river at the border, but farm runoff in Imperial County would assure a flow into the Salton Sea.

The planned sewer construction is “just the tip of the iceberg,” said Angel, the state water engineer. “But I’m optimistic.”