Updated 2:50 p.m. to include information from Mark McPherson and 5:25 p.m. to include comment from WiLDCOAST.
A broken sewer line in Mexico caused a two million gallon sewage spill Tuesday, County of San Diego Department of Environmental Health officials announced Wednesday.
The spill occurred at noon and persisted until midnight and flowed into the Tijuana River.
Shoreline from the U.S.-Mexico border to the end of Seacoast Drive have been closed since March 17 and will continue until county health officials deem the water safe for human contact.
Further north, beaches near the Imperial Beach pier and Silver Strand State Beach have not been closed as a result of the spill.
Though the SCCOOS plume tracker shows flow from the river heading north, local lifeguards said they were instructed by county health officials to take down beach closure signs Tuesday after potentially sewage contaminated water from the river .
The plume tracker is one piece of a puzzle, said Mark McPherson, who heads the county's water quality public health body. Currents are heading slightly south, he said, and so sewage seems to be "collecting outside the [river] mouth."
Other factors taken into account include water sample results, strength of river flow, surface conditions, what the water looks like and observations by local lifeguards.
"We aren't going to close them unless conditions change, but as of right now, looking at surface conditions along with current, we're going to keep them open for right now," he said.
, the Imperial Beach based conversation and environmental group, said the spill was a good example of .
"Accidents happen, but there are concrete measure and specific infrastructure upgrades that can be made to reduce the risk of sewage spills and polluted beaches," said Paloma Aguirre with WiLDCOAST.
"We can no longer afford to continue to jeopardize the health of ocean users, our tourism economy, and the brand new because of the accidental release of sewage,” she said.