Abstract
Microbial water quality can be an important indicator for human health risks at recreational beaches. It is used globally for monitoring and public advisories. Historical data sets for recreational beaches, including swim advisories, have resulted from water quality monitoring programs. These historical data sets have the potential to provide insight into longer-term changes at recreational use sites and better inform health advisories. This study investigates the relationship between counts of the fecal indicator bacteria (FIB) enterococci and tidal cycles at seven recreational sites in Biscayne Bay using historical monitoring data collected by Miami Waterkeeper. Samples were taken at the seven sites from January 2018-January 2020 and analyzed in the lab for the most probable number (MPN) of enterococci. We find insufficient evidence to suggest a relationship between microbial water quality and ebb or flood tide at any of the sites, as well as insufficient evidence to suggest any significant difference between microbial water quality at the different sites. The limitations of our study using this historical monitoring data, in the context of other research, suggest that modifications to data collection protocols could benefit future long-term studies at these sites without compromising short-term advisories.