The loss of agricultural chemicals in runoff from agricultural land is a major cause of poor surface water quality in the United State. Scientists (NRCS) developed a technique to estimate the impact of agricultural watersheds on natural water resources. The objective of this study was to apply this technique on the Wagon Train (WT) watershed to predict loss of alkaline earth elements (Ca, Mg, Ba, and Sr) by runoff from soils, and to estimate elements loading into WT reservoir. The predicted losses of Ca, Mg, Ba, and Sr by runoff were 67.5, 19.9, 0.17, and 0.05 kg/ha/yr, respectively. These data give a total annual loss of 262.1 Mg Ca, and 77.1 mega gram Mg for the entire watershed and could be considered as the annual loading for WT reservoir. Lower values were predicted for Ba and Sr. The total annual loss was  668 kg for Ba and 186 kg for Sr and could represent the annual loading for the reservoir. The predicted Ca, Mg, and Ba concentrations in runoff were in good agreement with those observed in water samples collected weekly from the main watershed's stream. However, the predicted Sr concentration in runoff was much lesser than that observed in the stream water. Subsurface seepage into the stream might contribute to the high Sr concentration observed in the stream water. We concluded that the technique could provide a reasonable estimation of  Ca, Mg, and Ba losses in runoff from agricultural watersheds and loading into surface water bodies.