Water Quality, Contamination, and Wetlands in the Croton Watershed, New York, USA

The Croton Watershed (New York State, USA) is a semi-urban region that provides 10% of the drinking water for the City of New York. Nonpoint source contamination in the watershed is a major concern for managers because the water supply is currently unfiltered water. Results are reported from three synoptic studies of surface water quality from 98 wetland-containing sub-catchments in the Croton Watershed designed to broadly characterize, at a reconnaissance level, the geochemical controls on water quality, in particular as it relates to wetlands. Total dissolved organic carbon concentrations in surface waters draining wetlands correlated well (average R2 of 0.93) with standard Gelbstoff (g440) color measurements, although there is very little correlation between dissolved organic carbon concentrations and wetland areas in the sub-catchments. This may be a potential indication of other sources of colored organic material. Concentrations of dissolved sodium and chloride, while related to road length, stochiometrically had more chloride than expected for pure road-salt dissolution. This offset is likely due to cation exchange and sorbtion of sodium by wetlands in the Croton watershed. The results show contamination in the Croton hydrologic system that should addressed in ongoing management policies and decision-making.