The initial report by the U.S. International Boundary and Water Commission told of a 212,000-gallon spill from Mexico into the Tijuana River channel.
But four days after the incident occurred, the group Monday issued a rare retraction.
The flow "was the result of a U.S. discharge," Steve Smullen, San Diego operations manager for the commission, said in an email. The commission is the U.S. branch of a binational agency charged with monitoring and reporting any renegade flows into the Tijuana River channel.
The great majority of such spills have come from Mexico, an issue that has caused concern in recent months in San Diego County. The incidents have led to closed beaches, as the water often carries sewage and other contaminants from Tijuana into San Diego and eventually the Pacific Ocean.
In an interview Monday, Smullen said: "I kind of jumped the gun" by sending out the initial report of the spill, which occurred during the early morning hours of Aug. 23.
The flow did not come from Mexico, but emanated from the San Ysidro Port of Entry, which is undergoing a massive reconstruction. The San Diego Regional Quality Control Board issued a permit to the U.S. General Services Administration to discharge water into the channel as they "try to maintain ground water low enough to where they can do their excavation," Smullen said.
The GSA, which is overseeing the project, has been treating any water that is discharged into the river, as stipulated in its permit, Smullen said.
Smullen said that before issuing any reports of spills, he normally checks with the commission's Mexican branch. Although his staff was aware that the spill did not come from Mexico, Smullen said, "I wasn't informed about it, so I made an assumption, and it was not a good thing to do in this case."