TIJUANA, Mexico (KGTV) -- February's sewage spill in Tijuana that resulted in millions of gallons of wastewater washing onto San Diego's South Bay coastline prompting numerous complaints from nearby residents, may have gone unnoticed for several weeks, according to investigators at the International Boundary and Water Commission.
On Monday, the IBWC released a report that cites blocked or collapsed sewer pipes, and the heavy rains that overwhelmed the sewer systems caused an estimated 28 million gallons of wastewater to flow into the Tijuana River Valley, impacting both the U.S. and Mexico.
The report also found that "sanitary sewer overflows caused by above-normal rainfall may have begun as early as December 2016."
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South Bay residents are still reeling from the raw sewage that flowed through Imperial Beach along the Tijuana River for 17 days. It wasn’t until angry residents of Imperial Beach began to complain about the smell of polluted water before anything was officially reported.
In early reports, United States Environmental Protection Agency officials estimated that 230 million gallons of raw sewage spilled into the water, but the IBWC report says "the amount could not be precisely determined."
Miguel Lemus, man in charge of Tijuana’s water department, previously said the spill was only 9 million gallons and contained in four days.
According to the report, hydraulic work started on Feb. 1, the day a collector collapsed, and repairs were completed on Feb. 23.
The IBWC report "documents multiple challenges faced by the Tijuana utility (CESPT) when winter rains entered the city’s aged wastewater system and overwhelmed it, causing collectors to collapse and sanitary sewers to overflow."
"The utility attempted to contain sewage flows while making repairs by directing wastewater into other pipelines," the report says.
"The location of the broken sewer line is in the area just upstream of the confluence of the Alamar and Tijuana Rivers (Figure 2), approximately 6 miles (10 km) from the international boundary," the report says.
In addition to gathering facts surrounding the massive spill, the task force provided a list of recommendations on preventing and containing sewage-contaminated runoff.
“This report provides concrete recommendations to help us properly respond to and prevent transboundary spills. It also has some reasonable and effective ideas as to how to speed up notifications,” said U.S. Commissioner Edward Drusina. “The Commission is committed to partnering with other agencies to use the report’s findings to make improvements.”