Association of Urban Runoff with Coastal Water Quality in Orange County, California

Abstract

The associations between storm events, urban runoff, and coastal water quality have not been well investigated. A temporal and spatial analysis of 2 years of data was conducted to determine associations between urban river discharge and indicator bacteria levels for Southern California beaches and evaluate the contribution of anomalous precipitation to the association. Data show beaches next to rivers had the highest bacterial levels in both wet and dry seasons. Bacterial levels rose substantially across all sites during wet months, and river discharge and bacterial levels were all highest during the winter with the most rainfall. Precipitation was significantly associated (Spearman rank bivariate correlation, P Ͻ 0.01) with water discharged from the rivers. River discharge was significantly associated with bacterial levels at 20 out of 22 beaches, with the strongest associations at sites next to rivers. The results indicate that urban river discharge is a primary source of Southern California's coastal water pollution and, as a result, swimming at beaches near rivers may pose a significant public health risk. The strong association found between precipitation and water pollution may be relevant to studies of potential health effects associated with climate change. Water Environ. Res., 74, 82 (2002).

Genomic island genes in a coastal marine Synechococcus strain confer enhanced tolerance to copper and oxidative stress

“…Increased runoff, a deeper mixed layer and decreased temperature can lead to an increase in many environmental stressors (that is, anthropogenic toxins, fecal bacteria (Dwight et al, 2002)) and an increase in dynamic conditions. So while copper might not be the driver of this trend, the more important point is that a genomic island gene that is known to confer stress tolerance in cultures is more abundant in the winter months, when many different environmental stressors are increasing, irrespective of seasonal variability in the main group, in which the gene has been found.…”

Microbiological evaluation of fecal bacterial composition from surface water through aquifer sand material

“…Part of the Santa Ana River continues to flow and empties into the Pacific Ocean near Huntington Beach. In southern California, it is well recognized that a major cause of bacterial pollution of coastal waters is urban runoff in rivers/channels and storm drains that discharge into the ocean (Dwight et al 2002;Reeves et al 2004). In a recent paper enumerating enterococci in marine and intertidal sediments (Ferguson et al 2005) for this may be inactivation of indicator bacteria by UV radiation in the filtration.…”

Enterococci in the Environment

“…In large bodies of water, such as the upper Chesapeake Bay, more than 80% of indicator organisms, including fecal streptococci and fecal coliforms, were found to be associated with suspended sediments (282). Such processes are often mediated by mechanical disturbances during recreational activities (7), hydrometeorological events (including high-flow, wind, and erosional conditions [116,175,274,312] and river outfalls [98,249]), as well as dredging operations (134,135). Collectively, such events can increase FIB densities in the water even in the absence of any significant human inputs.…”