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It is reported that phosphorus level showed increasing trends in groundwater, river, spring water, and private drinking water wells in the Suwannee River Basin of Florida. Quantification and characterization of nutrients in groundwater at a dairy farm are necessary steps to provide fundamental data and knowledge for nutrient management. This paper was to investigate long-term temporal and spatial distribution of soluble reactive phosphorus (SRP) in groundwater at a dairy farm under actual production conditions. Twenty one monitoring wells were installed at different dairy farm components for monthly groundwater sampling from 2000 to 2007. Rotational grazing was conducted since 2004. The results indicated that large variability existed in temporal and spatial distribution of SRP in groundwater at different land uses. Yearly average SRP concentrations in the groundwater were high to 8 mg/L and 13 mg/L near lagoon and at drainage area, respectively. In contrast, average SRP concentrations in the whole research period were less than 1 mg/L in the groundwater at intensive area, pasture, and sprayfield areas of the dairy farm. In addition, data indicated that possibly, there was direct seepage of SRP from the unlined lagoon of dairy wastes to the groundwater. Therefore, it may be necessary to set up a lined lagoon to reduce potential SRP contamination to groundwater at a dairy farm on well drained sandy soils. Also, runoff should be collected in the lagoon rather than flowing into nearby surface water or infiltrating into the soil profile and leaching down to the underneath groundwater.