California Ocean Plan: Developing Bacterial Water-Contact Standards

Abstract

The California Ocean Plan (Ocean Plan) sets bacterial water quality standards for ocean waters to ensure the protection of two beneficial uses: water contact recreation and shellfish harvesting. Water quality objectives contained in the Ocean Plan are incorporated into discharge permits issued by Regional Water Quality Control Boards. The first Ocean Plan, adopted in 1972, contained total and fecal coliform standards. Little has changed since then; an enterococcus monitoring requirement was added in 1990 at the United States Environmental Protection Agency's (USEPA) insistence that enterococcus is a superior indicator of human health effects in marine waters. The State Water Resources Control Board (SWRCB) staff began their review of the bacterial standards in 1992. Over the ten year review period, a several things have been done to investigate the question of how best to measure bacterial water quality in California marine. Some of the areas that have been addressed in this review are: does enterococcus monitoring provide additional useful information in waters beyond the beach? Do the various analytical methods used during routine monitoring provide results that are comparable? Is it possible to differentiate sources of fecal pollution? A review of discharger data compared the environmental fate of total coliform, fecal coliform, and enterococcus based on historic monitoring data. Results demonstrated that when fecal contamination is present, all three indicators respond similarly, and from a risk management perspective, enterococcus levels seem to add little to the information provided by the coliform data. Work on comparing analytical methods in fresh, estuarine and marine waters is ongoing. Preliminary results suggest differences in the methods; statistical analyses will be done to determine if the differences are sufficient to require the development of test-specific bacterial standards. The preliminary results also show(strongly samples from a pristine mountain river contain high concentrations of enterococcus but low concentrations of E. coli. And, based on the results from two SWRCB studies, it appears possible to differentiate sources of fecal pollution, but much more work is needed before any method can be viewed as reliable.