Rainfall effects on beach water quality in southern California are large enough that county health departments typically issue warnings for the public to avoid recreational water contact for 3 days following a storm. To enhance the scientific foundation for these preemptive public health warnings, we examined the relationship between rainfall and beach indicator bacteria concentrations using 5 years of fecal coliform data taken daily at 20 sites in southern California. There was a countrywide increase in ocean bacterial concentrations associated with almost all storms larger than 6 mm and with every storm larger than 25 mm. Only for storms less than 2.5 mm was there no observable rainfall effect. Bacterial concentrations remained elevated for 5 days following a storm, although they generally returned to levels below state water quality standards within 3 days. The length of the antecedent dry period had a minimal effect on this relationship, probably reflecting a quickly developed equilibrium between the decay of older fecal material and the introduction of new fecal material to the landscape.
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Research Article|June 01 2003
Relationship between rainfall and beach bacterial concentrations on Santa Monica Bay beaches
Drew Ackerman
Drew Ackerman
1Southern California Coastal Water Research Project, 7171 Fenwick Lane, Westminster, CA 92683, USA
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Stephen B. Weisberg
Stephen B. Weisberg
1Southern California Coastal Water Research Project, 7171 Fenwick Lane, Westminster, CA 92683, USA
Tel.: +1 (714) 372-9203 Fax: +1 (714) 894-9699; E-mail: stevew@sccwrp.org
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J Water Health (2003) 1 (2): 85-89.
Citation
Drew Ackerman, Stephen B. Weisberg; Relationship between rainfall and beach bacterial concentrations on Santa Monica Bay beaches. J Water Health 1 June 2003; 1 (2): 85–89. doi: https://doi.org/10.2166/wh.2003.0010
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