Phosphorus concentration trends in the Saline River watershed, USA

Summary

Water quality data from nine monitoring stations in the Saline Valley Rural Clean Water Project area were analyzed to determine if agricultural “Best Management Practices” (BMP's) were reducing total phosphorus, soluble reactive phosphorus and available phosphorus concentrations in the watershed. Data from a pretreatment year and two progressive treatment years were compared, using a covariate analysis model to correct for differences in discharge between years. Significant decreases in phosphorus concentration from years 1 or 2 to year 3 occurred in 13 of the 27 comparisons while significant increases from years 1 or 2 to year 3 occurred in only two of the comparisons. Soluble reactive phosphorus showed the most significant decreases. However, large increases in row crop acreage from years 2 to 3 may masked the effectiveness of BMP's in reducing concentrations of sediment-bound phosphorus in the water.