A function for the R programming language to recast garnet analyses into end-members: Revision and porting of Muhling and Griffin’s method

Agricultural pollution is a significant problem in North Dakota. Water quality in the Pipestem Creek watershed upstream of Pingree, North Dakota, USA, has been a major environmental concern amongst other adjacent watersheds within the region. The annualized agricultural non-point source (AnnAGNPS) model, a large-scale watershed model designed to predict sediment and nutrient loads, was used to evaluate non-point source pollution in a typical agricultural watershed. The best available data were assembled and used in the analysis. The model predicted runoff of 0.31 m3/s, compared to a measured value of 0.46 m3/s. A poor correlation was observed when comparing the modelʹs predicted nitrogen, phosphorus, and sediment with the observed counterparts. The modelʹs poor performance was most likely a result of the large size of the study area and the high variability in land use and management practices.