Storm effects on regional beach water quality along the southern California shoreline

Abstract

Two regional studies conducted during dry weather demonstrated that the Southern California Bight (SCB) shoreline has good water quality, except near areas that drain land-based runoff. Here, we repeat those regional studies 36 h after a rainstorm to assess the influence of runoff under high flow conditions. Two hundred and fifty-four shoreline sites between Santa Barbara, California and Ensenada, Mexico were sampled using a stratified-random sampling design with four strata: sandy beaches, rocky shoreline, shoreline adjacent to urban runoff outlets that flow intermittently, and shoreline adjacent to outlets that flow year-round. Each site was sampled for total coliforms, fecal coliforms (or E. coli), and enterococci. Sixty percent of the shoreline failed water quality standards after the storm compared to only 6% during dry weather. Failure of water quality standards increased to more than 90% for shoreline areas adjacent to urban runoff outlets. During dry weather, most water quality failures occurred for only one of the three bacterial indicators and concentrations were barely above State of California standards; following the storm, most failures were for multiple indicators and exceeded State of California standards by a large margin. The condition of the shoreline in Mexico and the United States was similar following rainfall, which was not the case during dry weather.

Real-Time PCR Quantification of Human Adenoviruses in Urban Rivers Indicates Genome Prevalence but Low Infectivity

“…Storm water and urban runoff are now recognized as major sources of coastal water pollution, as numerous studies suggest that shorelines receiving runoff fail to meet water quality standards (20,24,27,30,34). For example, a 90% increase in the frequency of violation of recreational water quality standards has been previously reported for shorelines adjacent to urban runoff outlets following rainstorms in Southern California Bight (30).…”

“…Southern California beaches have unquestionably become one of the most desired beach vacation spots in the world, attracting over 100 million visitors to the shoreline annually and offering recreational activities such as swimming, diving, yachting, surfing, snorkeling, windsurfing, and fishing. Correspondingly, an increase in the volume of domestic sewage discharge and urban runoff to the coastal ocean has become a major public health concern in southern California (21,30) and likewise nationwide.…”

Comparison of the presence and partitioning behavior of indicator organisms and Salmonella spp. in an urban watershed

“…Storm runoff can mobilize and transport fecal microorganisms from various nonpoint sources to receiving waters, resulting in elevated downstream microbial concentrations (Hunter et al 1992;Noble et al 2003;Kim et al 2005). Increased precipitation has also been linked to outbreaks of waterborne disease (MacKenzie et al 1994;Rose et al 2000;Gaffield et al 2003) and exposure to waters receiving stormwater discharges has been correlated with an elevated risk of illness (Haile et al 1999;Gaffield et al 2003).…”

Detection of Genetic Markers of Fecal Indicator Bacteria in Lake Michigan and Determination of Their Relationship to Escherichia coli Densities Using Standard Microbiological Methods

“…While progress has been made in identifying genetic markers that are useful for microbial-source tracking, few studies have evaluated how these markers vary temporally and spatially following contamination of surface waters (25), and even fewer studies have assessed their occurrence at beach sites (4,23). We assessed the prevalence of E. coli and total and human-and cow-specific Bacteroides genetic markers in surface waters of Lake Michigan impacted by multiple pollution sources following major storm events.…”