Investigating the impacts of best management practices on fecal indicator bacteria, Giardia spp., and Cryptosporidium spp. in stream water from California meadows

The loss in number and function of wet meadow ecosystems in California is often associated with reduced drought tolerance and impaired water quality in watersheds. This research focused on investigating the improvement of meadow health and water quality by implementing best management practices (BMPs), particularly wildlife-friendly, cattle-exclusion fencing (allowing passage of wildlife) along streams, in a multi-use riparian wet meadow system. This longitudinal study followed the concentration of fecal indicator bacteria and fecal pathogens in the stream water from 2017 through 2022. Total coliforms, Escherichia coli , Giardia cysts, Cryptosporidium oocysts, and hydrologic parameters were monitored. The impact of the cattle exclusion fencing was evaluated using mixed-effect negative binomial and logistic regression models. Using EPA Method 1623, the overall prevalence of exceeding water quality standards for E. coli , Giardia spp., and Cryptosporidium spp. in the stream surface waters was 12.9%, 17.7%, and 27.1%, respectively. When the cattle exclusion fencing was present in a downstream location, E. coli in stream samples was reduced by 28 organisms/100 ml . Furthermore, significantly fewer water samples exceeded the regulatory thresholds set by the California State Water Resources Control Board when exclusion fencing was present. No statistically significant association was detected between fencing and the presence of Giardia spp. or Cryptosporidium spp. The hydrologic data revealed that the valley floor held more water over time, which was released more slowly throughout the year. This indicates that the wet meadow function is recovering, and suggests that using BMPs, including wildlife-friendly cattle exclusion fencing, in a multi-use wet meadow ecosystem that includes ranching, can help improve surface water quality and ecosystem health. • Protozoal pathogens in streams were detected throughout 5 years of meadow restoration. • Cattle exclusion fencing was associated with reduced freshwater stream E. coli concentrations. • Stream E. coli concentrations decreased by 28 organisms/100 ml at riparian fencing locations. • Cattle exclusion fencing was associated with improved water quality in California meadows.