[Submitted for publication]
Microbial indicators of marine recreational water quality in Maui, Hawai`i: Assessing waterbody impairment in relation to known pollution sources
Mailea R. Miller-Pierce and Neil A. Rhoads
Abstract: The Hawai`i Department of Health uses the fecal indicator bacteria (FIB) enterococcus (ENT) to evaluate recreational water quality and risks to human health. ENT can originate from non-human sources requiring the informal use of Clostridium perfringens (CP) as a secondary microbial indicator; however, no official state standards exist for CP. The distribution of values from ~16,000 ENT samples collected between 1989-2016, were used to establish a new and corresponding set of standards for ~14,000 CP samples. At 73 coastal sites on Maui, FIB concentrations were compared to water quality standards to investigate whether exceedances were more frequent near wastewater reclamation facilities (WWRF) and on-site disposal systems (OSDS, i.e. cesspools and septic systems). Sites of concern were identified based on FIB impairment and degradation of water quality over time; at many sites, concentrations have steadily increased over the last 27 years. Significant bivariate relationships between FIB occurred at 62% of sites.