Maintaining or establishing strips of close-growing vegetation adjacent to water bodies is a practice that can reduce sediment, nutrient, and fecal coliform contents of runoff water reaching them. Limited information is available on concurrent release and transport of manure-borne phosphorus (P) and enterobacteria from grass-applied manure. Under simulated rain, a continuum of particle sizes, between 0.1 and 100 µm, was detected in runoff throughout the 90-min simulation. Higher correlations were found between bacterium concentrations, turbidity, and phytase-hydrolysable phosphorus, a fraction primarily associated with particulate manure, or the more-inclusive total bioactive P or total P than to the manure water-extractable P component in runoff. Determination of bioactive P in runoff may complement enterobacteria counts to confirm bacterial release and these results demonstrate the need to quantify manure-borne bacterium released to runoff while associated with organic P-containing manure particulates. Given the micrometer size range of suspended particles in runoff from grass strips, they may not be effectively filtered to reduce lateral transport of colloid-associated fecal bacteria and organic P.