Pollution of waters resulting from P runoff from agricultural land receiving long-term manure application continues to be one of the most serious threats to water quality in many regions in the US. Dietary manipulation to optimize P supply and intake and minimize P excretion in manure is one of the most valuable and cost-effective approaches in lowering potential P loss in watersheds that have animal farming as a significant agricultural component. This study examines P concentrations in diets fed on over 90 commercial farms in the Northeast and Mid-Atlantic regions. Samples were obtained four times a year (March, June, September, December) from 2002 to 2004, resulting in a total of 1168 feed samples which were analyzed for total P concentration along with other nutritional parameters. Mean dietary P concentrations fluctuated between 4.0 and 4.4 g kg-1 over the 12 sampling times. When grouped into three categories, 29-60% were in the adequate dietary P range (<4.0 g kg-1), 25-40% in the moderately high range (4.0 to -4.5 g kg-1), and 11-32% in the high range (>4.5 g kg-1). There were no consistent trends of increase or decrease over the 12 samplings. When examined individually, the vast majority of farms showed no consistent change, although sporadic increase or decrease occurred on many farms during the 3-yr period. While it is environmentally vital and practically feasible to prepare diets containing adequate but not excessive P, the results of this study suggest that no substantial differences occurred during the 3-yr span, that is, the majority of the farms were “doing business as usual”. Better incentives and management tools are needed if we are to take the advantage of ration formulation and dietary optimization for the purpose of lowering P surplus and reducing potential P losses on dairy farms.