Phosphorus (P) enrichment of surface waters due to runoff from agricultural fields is a leading source of water quality impairment. Given the importance of agriculture to New York State's economy, it is critical to balance economic and environmental goals of farms, rural communities and public water resources. To reduce the risk of P runoff, New York State (NYS) released its P index in 2001. To assess the performance of the P index, two studies were conducted: (1) assessment of 30 dairy farms to determine distribution of P indices and their contributing factors on a whole-farm basis; and (2) determination of current statewide and county-based P-balances for New York State. For the first study, whole farm nutrient management plans were obtained. Farms ranged in size from 128 to 995 ha. For the second study, data from USDA-NASS AG Census and NYS Department of Agriculture and Markets were used to derive P inputs to cropland (manure production estimates and P fertilizer purchases) and P removal through harvested crops. Data were analyzed for 2002, 1997, and 1992. Preliminary results from the second study show P accumulations in several counties and indicate the impact of shifts in animal populations, fertilizer use and crop production on P balances. These budgets confirm a regional P imbalance in NYS. The current NYS P index is a best management practice that addresses immediate P allocation needs but it has limited use in addressing P accumulation and potential runoff/loss over the long term. For the long-term sustainability of the dairy sector and the environment, current best management practices need to be expanded to include source reduction and/or export of P.