Catherine Ashcraft

This paper was written as part of continuing studies of bacteria levels in tributaries of the Quinnipiac River, conducted at the Yale School of Forestry and Environmental Studies. Samples were collected from 9 sites on Sodom Brook’s mainstem, and from 2 of its tributaries. E.coli and fecal coliform data were collected for each site, in addition to temperature and pH. The sites were sampled during both stormflows and dryflows. A stream reach was identified with high bacteria levels for subsampling. This reach was subsampled once during a stormflow and a baseflow. Analyses of the bacteria data are presented with an emphasis on how flow relatiosnhips affect water quality assessment. A positive correlation seems to exist between E.coli and FC during dry flows, but no fixed ratio relating them is apprent from wet flow data. Data demonstrate that Sodom Brook regularly exceeds water quality standards for both E.coli and fecal coliform throughout its length. A much larger percent of exceedances occur during wet flows than dry flows. Conversely, a larger percent of the samples meeting water quality standards were taken during dryflows. This suggests that an accurate assessment of water quality requires a monitoring strategy that incorporates samples from both flows.