DIAGNOSTIC ASSESSMENT OF WARNER CREEK, CATSKILL MOUNTAINS, NY - THREE YEARS OF STUDENT CONDUCTED RESEARCH: CONCLUSIONS AND IMPLICATIONS

The New York City (NYC) water supply is currently unfiltered and largely sourced in the Catskill Mountains of New York State. The Catskill System, comprising Ashokan and Schoharie Reservoirs supplies up to 40% of the approximately 1 billion gpd delivered to NYC. This system is subject to periodic episodes of excessive turbidity originating from stream erosion into Pleistocene glacial deposits. Stream gage analysis for Esopus Creek (principal stream in the Ashokan Reservoir watershed) shows a clear trend in increasing frequency of very high flow events, starting in the 1980s. The increased turbidity conditions are assumed to be a water quality indicator of fluvial geomorphic response to a changing hydrologic regime. SUNY New Paltz and NYC Dept of Environmental Protection collaborated on a 3 year research project conducted by undergraduate students to assess and evaluate the geomorphic response of Warner Creek, a 12.5km long tributary stream in the Esopus Creek watershed.

During the summers of 2010-2012, eight students assessed Warner Creek through a combination of investigation techniques with the intent to diagnose the stream’s geomorphic condition following three years with high magnitude floods. The primary technique was annually repeated stream feature inventories for 3 km of the lower reaches to the confluence with Stony Clove Creek. Geomorphic features were mapped with GPS and ArcGIS. This created a time series of geomorphic feature maps that were then analyzed for changes and trends. Quantifiable changes in the distribution of large woody debris, migration of headcuts, and increases in bank and bed erosion, as well as depositional features document the channel’s response to a period of extreme hydrologic conditions, including Tropical Storm Irene flooding. Several other techniques were used in conjunction with the stream feature inventories: temperature profiling, suspended sediment fingerprinting, repeat cross section and longitudinal profile surveys, bankfull hydraulic geometry assessment, and stream corridor geologic mapping. The three year study has produced important findings that have stream management implications in a watershed that has chronic turbidity conditions.