Coastal Bacteria and Stormwater Runoff

The significant health issues correlated with urban stormwater runoff discharged into coastal waters is of prominent concern within the Orange County coastal zone of southern California because it is one of the most developed areas in the United States, and consequently, it produces some of the most highly polluted runoff. This study focuses on the improvements observed within Huntington and Newport beaches, since they have an unfortunate history of human illness related to their contaminated waters. A study by Given (2006) et al.,revealed the unhealthy effect these waters had on more than five million people who swam at the two beaches from 1998 to 2000—it showed record of about 36,000 cases of stomach ailment and 38,000 cases of respiratory, eye and ear infections caused by exposure to the polluted waters. Fortunately, water conditions within the area have displayed improvement. An initial increase of fecal bacteria concentrations was observed between the years of 2000 to 2005 (indicating poor water quality); however, bacteriological concentrations decreased during the period between 2005 and 2010 (indicating improved water quality). Lim and Jeong (2012) discovered that the stormwater runoff from the surrounding urban watershed is a primary source of fecal pollution in Orange County Beaches, so they inquired that efforts to improve water quality and protect beach-goers from pollution will likely have greater efficacy during wet weather periods than any other time of year. In addition, the study identified the effect of alongshore surf zone current on fecal pollution caused by coastal waves; moreover, their analysis elucidated methods to improve public health protection through management that is in compliance with coastal water quality standards.—Genevieve Heger
Lim, S., Jeong, Y. 2012. Decadal Trend of Coastal Water Quality in Orange County Beaches and Management Efficacy at Improving Public Health Protection. Journal of Environmental Science and Engineering A. 1: 967-979

Lim and Jeong conducted an extensive study of the water quality conditions at Huntington and Newport beaches. The site was divided into four stations (two per beach), and each was analyzed for concentrations of fecal indicating bacteria(FIB)–total coliform (TC), fecal coliform (FC), and enterococci bacteria (ENT)–between the decade of 2000 to 2010. The bacteriological data was analyzed using a defined substrate test known as IDEXX Colilert-18, and Enterolert. Empirical Orthogonal Functions (EOF) analyses in addition to periodogram analyses (using Matlab computer program) were also carried out for each of the three FIB. The precipitation records for the local area were obtained from a rain gauge at John Wayne Airport in the City of Santa Ana, which is approximately 23 kilometers northeast of the study site. Lifeguards kept record of wave conditions, including both direction and height of breaking waves (twice per day, once at 7:00 and again at 14:00 local time).
Lim and Jeong concluded that TC concentrations were significantly correlated with rainfall, while FC and ENT concentrations were somewhat correlated. It was also observed that all FIB concentrations were above average during the January-February-March period (i.e. winter months), which is when most rain falls in southern California. This observations correlates with their discovery that the coastal area exhibits an annual return period. Lastly, they found through observation of wave conditions, that contaminants are transported parallel to shore by wave-driven currents, in a direction (upcoast or downcoast) controlled by the approaching wave field. Lim and Jeong’s discoveries suggest a prospect for further water quality improvement.
Reference:
Given, S, Pendleton, L.H., Boehm, A.B.  2006. Regional public health cost estimates of contaminated coastal waters: A case study of gastroenteritis at southern California beaches, Environmental Science and Technology. 40: 4851-4858.

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