Cannonsville Reservoir

Cannonsville Reservoir, built in 1967 as part of the Delaware System of the New York City water supply, is the largest of 19 reservoirs in the entire NYC system.  The Cannonsville watershed covers 455 mi2 (1178 km2) and contains the largest agriculture land cover (19% of the catchment area) of all reservoirs in the system.  After significant investment and implementation of point- and non-point source pollution reduction programs, Cannonsville has seen a decline in both total phosphorus and Trophic State Index. Currently, Cannonsville’s water quality is in the mesotrophic range based on Carlson’s Trophic State Index derived from chlorophyll a measurements. Recent research in the Cannonsville basin, a headwater reservoir with a water residence time of about 4 months, is focused on understanding carbon sources and how they translate into disinfection by-product formation potential. http://www.nyc.gov/html/dep/html/watershed_protection/cannonsville.shtml