Surface water runoff from large livestock operations finds its way into streams, rivers, and ultimately the larger watershed area. In this paper, the model measures the nitrate concentrations in the upper North Bosque (Texas) watershed, which is a region of concentrated dairy operations. Using 15 months of daily data collected at 17 stream monitoring sites allows the authors to obtain optimal predictions of unknown nitrate concentration at all stream locations at any given time, along with a measure of their variability.