Biological Stream Survey of Lower Esopus Creek, Catskill Mountains, New York

Spillovers and releases from the Ashokan Reservoir into the Lower Esopus Creek have been observed to increase discharge, water level, and turbidity. Concerns about these effects on drinking water quality and stream ecology have spurred debate between the New York City Department of Environmental Protection (NYC DEP) and citizens living within the Esopus Creek watershed. This study was designed to assess Lower Esopus Creek health, compare current conditions to those in 2007, and identify controlling factors in benthic macroinvertebrate (BMI) distribution. Samples were collected, twice in July, at seven sites below the reservoir, six sites along Lower Esopus Creek and one on Sawkill creek (a tributary to Esopus Creek). Data was collected under both normal flow conditions and after a storm event. BMI and water samples were collected at each site. The BMI samples were collected, stored, and evaluated according to the 2009 New York State Department of Environmental Conservation (NYS DEC) protocol for Biological Monitoring of Surface Waters in New York State. Physical habitat and water chemistry parameters were also measured in the field. During this sampling period, the same methods were used at seven sites in the Stony Clove Creek and its tributaries. Non-parametric tests were used for analysis due to the small sample size and non-random nature of the sampling. The results showed no significant differences in BMI populations between normal and high flow conditions, or between 2007 and 2011. BMI population, total dissolved solids (TDS), turbidity, current, and dissolved oxygen (DO) were not significantly correlated to distance downstream from the reservoir. BMI population was significantly correlated to TDS and DO, but was not significantly correlated to turbidity. There are no significant longitudinal trends in Lower Esopus Creek; therefore stream ecology is probably more affected by local conditions than by impoundment effects from the Ashokan Reservoir.