A mechanical breakdown and construction work at some U.S. sewage facilities allowed more than 2.1 million gallons of wastewater from Mexico to flood the Tijuana River Valley in San Diego County in early June.
Unlike most other spills of that size, it has prompted scant enforcement action by water-quality regulators and no cleanup.
The incident ranks as one of the county’s largest sewage-related accidents in the past decade, and one that likely would prompt hundreds of thousands of dollars in penalties if it was caused by a local agency.
A top regulator at the San Diego Regional Water Quality Control Board said he doesn’t plan to issue fines because the U.S. section of the International Boundary and Water Commission is exempt from them under the principle of sovereign immunity.
Federal facilities can deflect some environmental fines under a legal theory that is thought to have its roots in Britain. The policy shielded the king from being sued in his own courts. Congress has removed the waiver from various laws but not the Clean Water Act.
“We have one hand tied effectively behind our back,” said David Gibson, executive officer of the regional board.
Gibson said the investigation has been complicated because the discharge started in Mexico, where he has no authority.
The boundary commission took required steps to notify local agencies about the sewage spill in a report but didn’t try to recapture the liquid, Gibson said. He said it’s not clear what restoration steps the commission must take because it didn’t cause the spill.
“We are going to have a meeting with them to clarify roles and responsibilities, and coming out of that we will consider our compliance options,” he said.
Alternatives include issuing a cleanup order, but Gibson wouldn’t commit to a strategy before consulting with the commission.
He also said the overflow raised questions about the level of maintenance the federal agency must do at its sewage diversion structures.
“That is certainly one of those things we will address in black and white … in the next permit” issued for operating those facilities, Gibson said.
Commission spokeswoman Sally Spener said her agency took precautions to prevent the wastewater spill from reaching the river valley, but that its efforts were undermined by “unforeseeable circumstances.” Spener said the commission has not changed any policy or procedure because of the incident.
“I think that everyone who is involved with this understands that the true solution is to have improvements in the wastewater collection system in Mexico,” Spener said.
Other regulators said that is not the only issue.
“Even though the source is south of the border, it is bypassing U.S. taxpayer-funded infrastructure that was designed to capture that flow,” said Bart Christensen, a senior engineer for the State Water Resources Control Board in Sacramento who has spent 25 years working on wastewater issues in the San Diego-Tijuana region.
“If there were (millions of gallons) of sewage spilled anywhere else, you couldn’t say, ‘Well, gee. We were working on something, therefore our system was down,’ ” Christensen said.
South Bay conservationist Paloma Aguirre was planning a trash cleanup event for the nonprofit group Wildcoast in early June when she noticed sewage streaming through the Tijuana River Valley.
“It was black and there was a definite smell,” Aguirre said.
The source was uphill in Mexico, where an estimated 5 million gallons of sewage were released June 2 and 3 and then funneled to the United States through Smuggler’s Gulch.
On the U.S. side of the border, that region is sparsely populated by farmers and ranchers. Much of the nearby land is protected habitat for birds and other species.
Problems in Smuggler’s Gulch started the morning of June 2 after workers in Tijuana shut down the Matadero Pump Station to fix a broken sewage line, according to a report by the boundary commission.
The commission’s report said the Smuggler’s Gulch collector captured all the wastewater from Mexico until 4:30 p.m. At that point, the pumps couldn’t keep up and the sewage ran into the Tijuana River Valley until about 8 a.m. the next day, the report said.
Spener said one of the boundary commission’s pipes for shunting sewage to its nearby wastewater treatment plant was out of service at the time because another pipe was being placed underneath it during upgrades to the system. She said the project had been coordinated with officials in Mexico in hopes of avoiding problems.
“We waited to cut (the pipe) until we thought we were ‘all clear’ regarding potential spills,” Spener said. “We still had one line in service and we felt that would be adequate to handle any flows that came across” from Mexico.
She said the temporary system was working until a breaker on one pump kept tripping, forcing it out of action.
MAJOR SEWAGE SPILLS
Over the past decade, San Diego County has had several spills of more than 1 million gallons. The incidents include:
June 2010: A mainline break in Mexico released more than 2.1 million gallons of untreated wastewater into the Tijuana River Valley.
March-April 2007: A ruptured pipe spewed 7.3 million gallons of sewage into the Buena Vista Lagoon.
November 2004 to November 2006: At least 14 million gallons of sewage flowed undetected from Navy barracks into San Diego Bay.
October 2004: Wastewater and debris clogged the Point Loma treatment plant, sending 2.26 million gallons of sewage into the ocean.
February 2004: A blocked sewer line in Balboa Park caused 4.9 million gallons of sewage to flow into San Diego Bay.
August 2003: A line break led to a 1.5 million-gallon spill at a treatment plant operated by Oceanside.
April 2003: A line break caused a 1.2 million-gallon spill in the Rainbow Municipal Water District.
February 2001: A clogged sewer line caused Mission Bay to become contaminated with about 1.5 million gallons of sewage that had overflowed into Tecolote Creek.
September 2000: About 2.7 million gallons of sewage spilled from a Camp Pendleton housing complex into the Santa Margarita River estuary.
February 2000: A clogged sewer line along Alvarado Creek went undetected for a week, allowing 34 million gallons of sewage to flow into the San Diego River.