ABSTRACT: The water quality objective of the New York State Model Implementation Program (MIP) was to reduce phosphorus (P) loading to the Cannonsville Reservoir, a eutrophic impoundment on the West Branch of the Delaware River that supplies drinking water to New York City. The MIP focused on controlling P losses from animal waste sources in the rural watershed, particularly dairy barnyards. Results indicated that runoff from the West Branch watershed during the winter-spring period accounted for more than 80% of the annual loading of dissolved and total P to the reservoir. Reductions in barnyard P losses of 50% to 90% were shown to be achievable using practices that reduced the volume of runoff from these areas. However, the contribution of P from barnyard runoff was substantially less than that from manure-spread cropland in the budget for annual losses of dissolved and total P in the West Branch watershed. Manure spreading schedules that guide the location and timing of spreading had the potential to reduce P loading from the studied subwatershed by as much as 35% in the absence of short-term or long-term manure storage systems. Because treatment of cropland was given only limited attention by the MIP, P loading reduction attributable to the program as well as the response of the reservoir9s water quality were negligible.