The push to explore a potential Superfund designation for the Tijuana River Valley hit a snag Wednesday when the U.S. Environmental Protection Agency told San Diego County leaders that the federal agency’s priority is to control the flows of sewage and trash that spill over from Mexico. Investigating potential contamination in the border region was best left to the state, they said. Last week, the federal agency denied a petition to review whether a six-mile stretch of the lower river valley qualifies as a Superfund site, a determination it made based largely on data from 2018 and 2019. That data, collected by the U.S. Customs and Border Protection and the International Boundary and Water Commission, found concentrations of hazardous chemicals in water and sediment, but not at levels that exceeded the EPA’s regional screening levels for human health concerns. County Supervisor Terra Lawson-Remer, who spearheaded the October petition request, asked an EPA official on Wednesday why the federal agency would not take new samples given that pollution has worsened in recent years with the industrial growth in Tijuana. “I just feel like not taking the soil site samples is like an ostrich putting our head in the sand saying, ‘Oh, we don’t know (for) sure there’s a problem,” said Lawson-Remer. “I would love it if you guys came out and did these site studies and told us like, ‘Nope, it doesn’t qualify for a superfund site. … Then we would know it wasn’t as toxic as I fear.” Michael Montgomery, director of the EPA’s Superfund and Emergency Management Division, told the Board of Supervisors that “the highest priority” isn’t sampling, but rather plugging the volumes of untreated wastewater and trash that flood the river valley. “That’s really the answer here,” he said. “There’s also a valid argument that until you can reduce that transboundary sewage flow, it’s hard to really (set a level) on what … contamination might be in the sediments.” The EPA had also denied the petition because it did not identify a specific location to conduct sampling other than naming “the 6-mile stretch of the Lower Tijuana River Valley.” The area refers to the stretch of the Tijuana River that crosses the border, the river valley and estuary, and ultimately flows into the Pacific Ocean. This river portion has repeatedly failed to meet water quality standards because of the continuous volumes of pollution from Mexico. Montgomery said a six-mile stretch is “really large” to sample and could cost upwards of $100,000. “We just don’t have that type of money to look everywhere for everything,” he added. A better approach, Montgomery added, would be to have the state Department of Toxic Substances Control and the San Diego Regional Water Quality Control Board confirm the need for sampling and collect data, if necessary. The regional water board, which has the authority to address both hazardous substances and human waste under the Clean Water Act, last month approved a 183-page plan to reduce trash and indicator bacteria in the lower river valley, ultimately restoring water quality standards over the course of several years. The water board has also included the Tijuana River on the EPA’s Clean Water Act list of impaired waters. Imperial Beach Mayor Paloma Aguirre told supervisors during public comment that they should submit a new petition to the EPA, a move Montgomery welcomed. The board did not discuss whether they would send a request for a superfund designation in the future, but agreed to explore other possible options, including working with the regional waterboard.