Studying cross shelf transport processes near an ocean outfall: San Pedro Shelf, California

Beginning in July 1999 the Orange County Health Care Agency began to post and close large sections of beach located in the City of Huntington Beach, California due to bacterial contamination. Extensive studies to date have yet to definitively identify the source or sources for these bacteria. One proposed hypothesis is that the Orange County Sanitation District's (District) submerged, offshore wastewater plume is the source. The hypothesis states that during the summer when the water column is most stratified the wastewater plume was being transported toward shore whereupon it then interacted with a local electrical power generation station's intake and/or thermal discharge plume to cause the observed chronic shoreline microbiological contamination. In response to this hypothesis, the District implemented an intensive, multi-faceted, multi-agency research study during the spring to fall 2001 to study both high and low frequency cross-shelf oceanographic transport processes on the San Pedro Shelf that could bring the plume toward shore.