For the first time since it was built in 1997, the South Bay International Wastewater Treatment Plant at the U.S.-Mexico border has met the standards set by the Environmental Protection Agency three months in a row, according to Steve Smullens of the International Boundary and Water Commission. With that accomplishment, 90 percent of Tijuana’s wastewater is now being treated to cleanliness standards equal to or higher than cities on the U.S. side of the border.

“It’s very good news,” said Dave Gibson, executive officer of the San Diego Regional Water Quality Control Board. “It’s an example of Tijuana’s growing commitment to the environment on both sides of the border. “

The border treatment plant’s final output is treated to secondary standards — cleaner than the city of San Diego’s, which fought for a waiver from the secondary requirement and treats only to advanced-primary standards. Once treated, the San Ysidro plant pumps effluent to the South Bay Ocean Outfall, about two miles offshore.

“The city of Tijuana is now producing cleaner wastewater day to day than the biggest U.S. city in the region,” Gibson said. “They’ve put a great deal of money and effort into it. Their lead agencies...put money into building and improving the plants in Tijuana.”

Most of Tijuana is served by four wastewater treatment plants. Two of those, Arturo Herrera and La Morita, which treat a total of 7 million gallons a day, produce “high quality” effluent — which is then pumped into the Tijuana River. The facility in the South Bay treats about 25 million gallons of wastewater a day.

The infrastructure in Tijuana wasn’t built with the backup pumps and bypass systems that most U.S. systems have, so working on the pipes can mean that the sewage is dumped into the Tijuana River. The last big sewage spills were in April — with 25 million gallons ending up in the Tijuana River — and in the U.S.

Last month, Tijuana gave notice to Imperial Beach, San Diego, the county, the water board, and other groups that 177,000 gallons of sewage were going to be released during a pipe repair. The response was immediate: No thanks.

“The pressure they felt made them back off from releasing it, and it didn’t happen,” border water commissioner Edward Drusina said at a citizens’ forum in Imperial Beach last week. “They are embracing a partnership with us.” Gibson agreed, pointing out that the U.S. has no jurisdiction or method to block the release of sewage in Mexico. Instead, he says, the growing relationships and cross-border investment are showing signs of improved sewage management.