Abstract
Factors that control water quality at recreational beaches are complex and generally poorly understood. This has led to a gap in policies written to address water quality. The objectives of the current study were to evaluate beach management and beach geomorphology, the influence of infrastructure improvements, and the role of unregulated nutrient inputs on recreational beach water quality, in an effort to inform decisions made by policy-makers. To evaluate these objectives three studies were conducted. These included 1) a study of beach management policies and fecal indicator bacteria (FIB)s to evaluate whether beaches characterized by a set of management policies are associated with lower FIB levels, 2) a study of the impacts of multiple septic to sewer conversion project improvements on FIBs over a large scale, and 3) a study of correlations between chlorophyll (measure of cyanobacteria biomass) and enterococci with nutrients, and of influence of the water’s source. In all of the studies, we assessed the impact of natural characteristics (geomorphology, geology, current/flow/tides, weather and environmental conditions). Laboratory, statistical, spatial, and temporal analyses were used to evaluate relationships between indicators of microbial water quality and anthropogenic impact in terms of the ways in which humans actually use the beach for recreation, as well as demands made on the environment due to infrastructure. We hypothesized that human use and, therefore, the policies that govern this use, would have both harmful and beneficial impacts on FIBs at recreational beaches. Results in the first study indicated that low enterococci exceedances were associated with open coast beaches, sparse human densities, low densities of dogs and birds, bird management policies, low densities of seaweed, beach renourishment, beaches that charge access fees, beaches that employ lifeguards, beaches without nearby marinas, and those that manage storm water. In the second study, we found that conversion from septic tanks to sewer systems does lower FIBs at nearby recreational beaches, but to observe trends from routine monitoring data, measures are to be aggregated across large time (17 year) and spatial scales (15 km). Trends can be altered by extreme weather events. In the third study, we found that cyanobacteria and enterococci at recreational beaches near rivers respond in similar ways to available nutrients (specifically nitrogen and phosphate), regardless of a connection to Lake Okeechobee. We also found that extreme weather conditions, such as hurricanes, can influence cyanobacteria and enterococci, indicating that both untreated runoff and lake water contribute to blooms and exceedances. In conclusion, we found that scientific understanding of the local environment, both natural and anthropogenic, is very important to understanding water quality. Collaboration among the agencies, appropriate funding, and knowledge of the capabilities of existing and proposed infrastructure should also be written into policy. Along with this, policies should reflect knowledge of the local community’s economic needs, expectations for use of local resources/ecosystem services, and the gaps in public scientific understanding of the local environment.