Fecal indicator bacteria, or FIB, sometimes found in the Malibu Lagoon and coastal ocean waters of Malibu may not be the result of human waste contamination, according to preliminary results of a new U.S. Geological Survey study.
The water quality study by the USGS was partially funded by the city, and is among four other studies contracted by the city to dispute the assertions by the Los Angeles Regional Water Quality Control Board that Malibu septic systems are the cause of bacterial contamination of the local watershed.
Malibu City Councilmember Jefferson Wagner said the results of the study vindicate the city’s argument that human waste is not the primary cause of contamination in the Malibu Lagoon and surrounding areas.
“We’ve pretty much called it like it is,” Wagner said.
The water board issued a controversial ban in September 2010 against septic systems in the central and eastern area of Malibu, which the state water board later upheld after the city appealed the ban.
Though the results of the study indicate that the regional water board was mistaken in the logic underlying the septic ban, Wagner said they would not affect the city’s plans to build a central wastewater treatment facility in the Civic Center area as demanded by the regional water board.
The wastewater treatment facility “will still be an asset,” Wagner said, “and I think it’s something we need to do.”
Malibu City Manager Jim Thorsen has been conducting negotiations with regional water board Executive Officer Sam Unger for four months on a two-phase approach to wastewater treatment in the area. A preliminary agreement announced by Thorsen in March would require commercial properties in the Civic Center to cease using septic systems by 2015 and share the cost of building a central wastewater treatment facility, estimated to be anywhere from $32 million to $52 million. Although not finalized, residential properties would be required to cease using septic systems by 2019.
Tests show that FIB concentrations routinely exceed U.S. Environmental Protection Agency public health standards for marine recreational water in Malibu Lagoon and occasionally exceed those standards at several Malibu beaches.
According to preliminary results of the study, scientists suspect possible sources of FIB to the ocean are kelp accumulated on the beach, discharge from Malibu Lagoon to the ocean, or movement of water from the lagoon through the sand berm separating the lagoon from the ocean. Scientists hope to know the exact source of the FIB to the near-shore ocean and the Malibu Lagoon once the study is complete.
The study utilized a combination of isotopic, microbiological, and chemical techniques. Isotopic techniques identified the source of water and identified when groundwater discharge to the lagoon and ocean were occurring. Microbiological techniques used DNA and other biogeochemical compounds to determine if organisms associated with human waste were present in groundwater, Malibu Lagoon, and the near-shore ocean. Chemical techniques used compounds associated with human use such as cholesterol, cosmetics, and plasticizers to determine if water had a history of human use.
“Data collected for this study indicate that fecal indicator bacteria and human-specific Bacteroides, an indication of human fecal material, are high in samples from within onsite wastewater-treatment systems; however, they are generally absent in samples from wells, even though many of the sampled wells contain water having a wastewater history,” Dr. John Izbicki, Research Hydrologist for the USGS, said.
Each year, more than 550 million people visit California’s public beaches. To protect beach-goers from exposure to waterborne disease, California state law requires water-quality monitoring for FIB, such as enterococci and Escherichia coli, at beaches having more than 50,000 yearly visitors. FIB are used to assess the microbiological quality of water because, although not typically disease causing, they are correlated with the occurrence of certain waterborne diseases.
For more information, a new USGS Open-File Report titled “Distribution of Fecal Indicator Bacteria along the Malibu, California, Coastlineâ” is available at USGS.gov