Timeline: 2009
Client/Partner: the University of California, Irvine – Prof. Stanley Grant
Study Location: City of Avalon
Role: Lab Manager
Background:
The City of Avalon, located on Catalina Island, is a recreational destination for boaters, fishermen, divers, beachgoers, and other ocean-oriented visitors. In 1999 the County of Los Angeles began testing Avalon Bay for fecal indicator bacteria in accordance with AB 411. These test results frequently exceeded California single-sample standards for fecal indicator bacteria in coastal bathing waters, and as a result beaches in Avalon have been frequently posted as unfit for swimming.
In response to these test results, a series of studies and mitigations efforts were undertaken. In 2000, Ms. Alison Davis in Jed Fuhrman’s laboratory at USC was hired to conduct a microbial source tracking study, to determine if there was evidence of human fecal pollution in Avalon Bay. This study, which was very small in scope, found no evidence of human viruses in Avalon Bay. Based on the results of this study, the City concluded that the fecal indicator bacteria problem in Avalon Bay was due to fecal material produced by birds, in particular pigeons.
Accordingly, the City focused on controlling bird populations in and around the City. In 2001, the City received a $500,000 grant from the State of California’s Clean Beaches Initiative to further investigate the water quality problem in Avalon Bay, and pursue mitigation measures.
This grant had three goals: 1) provide baseline monitoring information for water quality in Avalon Bay; 2) identify possible sources of fecal indicator bacteria in the Bay, 3) conduct microbial source tracking studies, and 4) characterize circulation in Avalon Bay.
Based on the study results, the City implemented the following mitigation measures:
a) Sewer mains and manholes in the first three blocks from the waterfront were slip-lined and sealed; this effort was completed in May, 2002.
b) Bird control measures were intensified; this ongoing effort was initiated in 2001.
c) Plumbing under the wharfs was repaired and a regular twice per year inspection program initiated.
d) Street wash down procedures were modified to prevent run-off.
e) Sewer laterals in the first three blocks from the waterfront were repaired and sealed; this effort was initiated in May 2005 and completed in November 2005.
Unfortunately, the mitigation measures described above did not result in substantial improvement in shoreline water quality, with the result that the main beach areas in Avalon Bay continue to be posted as unfit for swimming. Given the City’s substantial efforts to control contamination of the Bay from boats, dry weather runoff, bird droppings, and under wharf plumbing, attention has now focused on the possibility that sewage contaminated shallow groundwater is the primary cause of water quality impairment in Avalon Bay. In light of the above, the current Proposition 13 Clean Beaches Grant was funded to characterize the extent of
sewage-contaminated shallow groundwater; to conduct a pilot remediation study on sewage-contaminated shallow groundwater; to identify sources of fecal indicator bacteria (FIB) in ankle-
depth waters; and to improve sewer infrastructure.
UC Davis conducted laboratory analyses consistent with the MST monitoring plan outlined in the Work Plan for the Avalon Bay Water Quality Improvement Project.
Dr. Alexander Schriewer was responsible for the identification of fecal sources and human adenoviruses.