Banned pesticides and industrial chemicals found flowing from Tijuana into San Diego February 13, 2019
There may be more in the sewage-tainted water that regularly spills over the border from Tijuana than many San Diegans realize.
The cross-border pollution also contains potentially dangerous industrial and agricultural chemicals, according to a draft report compiled by U.S. Customs and Border Protection that was circulated to officials throughout the region on Wednesday.
The agency has been conducting water-quality testing since early 2018 in the canyons that empty into the Tijuana River Valley, where agents regularly chase down illegal crossers.
Along with high levels of bacteria from human waste, the testing found carcinogenic chemicals — such as the banned pesticide DDT and dangerous industrial compounds, such as hexavalent chromium.
“This is some horrible stuff,” said Christopher Harris, who has worked as a border agent in San Diego for more than two decades and is the spokesman for the National Border Patrol Council Local 1613. “This is affecting not just the border agents, but everyone who recreates down there.”
A number of the agents have suffered chemical burns and rashes after coming in contact with the polluted water, Harris said. “You’ve created one giant chemical waste dump in the Tijuana River Valley.”
The extent of the pollution has yet to be fully documented. Levels for any one contaminant were not dramatically high, according to water quality officials. But the list contained more than two dozen potentially dangerous substances, from uranium to the internationally banned pesticide Aldrin.
“Just one chemical by itself maybe it’s OK, but all together that hasn’t been evaluated, said Helen Yu, a water resource control engineer with the San Diego Regional Water Quality Control Board.
“Mostly for human health it’s pathogens in human waste that are most concerning,” she added.
The testing included 42 water samples over six months in several locations, including Yogurt Canyon, Goat Canyon, Smuggler’s Gulch, Canyon del Sol and Stewart’s Drain.
The agency now plans to perform an additional six months of water testing and start taking soil samples.
Spurred, in part, by the findings, the U.S. section of the International Boundary and Water Commission, or IBWC, started its own testing regime in December.
IBWC is sampling water and soil quality in the river valley to assess whether there’s been a toxic build up over time.
While pathogens in human waste can be dangerous, the material degrades relatively quickly. By comparison, many of the cancer-linked chemicals found in the testing can persist in the environment for years and could require a cleanup effort.
IBWC plans to monitor conditions through November on both sides of the border in coordination with officials in Mexico. They hope to identify pollution hot spots, which could lead back to specific businesses and other potential sources.
“We’ll try to figure out what could be contributing, if it’s coming in with the untreated sewage or if it’s being dumped,”said Gilbert Anaya, division chief for the environmental management division of IBWC.
Canyons in the Tijuana River watershed drain into San Diego through a series of culverts beneath the border fence.
IBWC has a collection system that divert flows in the river valley’s major canyons, such as Goat Canyon and Smuggler’s Gulch. Much of the polluted flows are sent to the South Bay International Wastewater Treatment plant.
However, the capture basins are routinely overwhelmed, especially in wet weather.
The state of California has sued the Trump administration for a violation of the Clean Water Act over the spills in the canyons. The move is aimed at forcing the federal government to expand the canyon diversion system and fund wastewater upgrades in Tijuana.
Lawyers for the defense have argued that the government isn’t legally responsible for the renegade flows that escape their collection systems, pointing out that the situation would be significantly worse without its efforts in recent decades.
Imperial Beach, Chula Vista and the Port of San Diego filed a separate lawsuit in March, which also takes aim at the pollution that regularly flows through the Tijuana River.
The state’s complaint was filed in federal court in September on behalf of the regional water board in San Diego. State officials have suggested their legal argument is strongest when applied to just the canyon collectors.
Tijuana’s aging and limited sewer system has in recent years struggled to serve the region’s growing population. Progress has been made thanks to Mexican and U.S. infrastructure investments, but experts and government officials agree that much more needs to be done to keep water pollution from spilling over the border.