Fecal pollution in coastal waters: Sources, transport, and public notification

The coastal zone is the unique environment where ocean meets land, and an important ecological, economic, and recreational resource. Urbanization of the ocean's coastline has significantly increased the flow of toxic contaminants and pathogenic microorganisms into the coastal zone. Coastal waters have many beneficial uses and they are a transport medium and a final repository for all manner of human waste. The latter inexorably diminishes the former, as evidenced by a wide spectrum of coastal ills, which threaten human health in manifold ways. In the U.S., public coastal beaches are increasingly off-limits due to elevated levels of fecal pollution and other contaminants. Mitigating this pollution, and communicating to the public health risk it poses is complicated by the high degree of complexity of coastal systems. Much of this complexity is associated with the spatial and temporal variability of the relevant physicochemical, biological, and oceanographic processes. These research challenges have not been well addressed historically, despite the obvious societal importance of a healthy coastline.; In this dissertation, I will examine the performance of public notification procedures for coastal water quality in California, and propose an alternative approach that is significantly less error prone. To identify the location, magnitude, and timing of fecal pollution sources along the shoreline, I describe a mass budget analysis for calculating pollutant loads into the surf by utilizing shoreline-monitoring data. The approach is tested on high frequency water quality data collected by the Orange County Sanitation District during the summer of 2001. The mass budget analysis reveals that fecal pollution at this site appears to originate from two coastal outlets and shoreward of a thermal outfall. I then describe the third investigation that specifically addresses the coastal water quality impact of fecal pollution from one or more tidal outlets. Based on field observations of dye experiment and long-shore transport in the surf zone at Huntington Beach, a mathematical model of shoreline water quality is developed and tested on high frequency monitoring data collected at the Santa Ana River and Talbert Marsh outlets, and in the adjacent surf zone. Finally, I develop a mathematical approach for converting measurements of pollutant concentration at the inlet and outlet of tidal saltwater marshes into information about whether the marsh is a net source or a sink of pollution. The latter model is tested against measurements of fecal pollution at the inlet and outlet of the Talbert marsh that drains into the surf zone at Huntington State Beach.; The methodologies described in this dissertation are quite general, and therefore should be applicable to a wide array of pollutants and coastal settings.