Submitted to: BARC Poster Day
Publication Type: Abstract Only
Publication Acceptance Date: 4/6/2017
Publication Date: 4/26/2017
Citation: Kierzewski, R.A., Pachepsky, Y.A., Stocker, M., Mulbry Iii, W.W., Shelton, D.R. 2017. Temporal stability of Escherichia coli concentration patterns in two irrigation ponds in Maryland. BARC Poster Day. 28th Annual BARC Poster Day, Beltsville, MD on April 26, 2017.
Technical Abstract: Fecal contamination of water sources is an important water quality issue for agricultural irrigation ponds. Escherichia coli is a common microbial indicator used to evaluate recreational and irrigation water quality. We hypothesized that there is a temporally stable pattern of E.coli concentrations across ponds meaning that there are areas that always have higher than average concentrations of E.coli and areas that always contain lower than average E.coli concentrations. To test this we sampled two irrigation ponds in Maryland biweekly during the summer of 2016. Thirty-four locations were sampled in one pond and 22 locations were sampled across another pond. In conjunction with E.coli concentrations, chlorophyll a concentrations and environmental covariates- temperature, turbidity, pH, DO, and nutrient concentrations were measured. Temporal stability was assessed using mean relative differences, Spearman correlation coefficients, and calculating empirical orthogonal functions. Temporally stable patterns in E.coli concentrations were indicated by all three methods. Temporal stability was found for most of the environmental covariates. Larger relative mean differences in algae corresponded to smaller mean relative differences in E.coli concentrations. Locations where E.coli concentrations remain close to the median value for the pond may be used to characterize the overall water quality of the pond. The temporal stability pattern in E.coli concentrations of ponds indicates that water quality for irrigation may be affected by intake location in the pond.