Determining the Effectiveness of Best Management Practices to Reduce Nutrient Loading from Cattle Grazed Pastures in Utah

The Utah Statewide Nonpoint Source Management Plan includes a list of recommended best management practices (BMPs) to reduce nonpoint source runoff pollution. These BMPs consist of management techniques and structural landscape designs for a variety of land uses. Here in Utah there is a lack of local data documenting the effects of agricultural BMPs to reduce nutrient runoff at a field scale. In this study, I evaluate structural BMPs designed specifically to reduce nitrogen and phosphorus levels from cattle grazing areas. Using a Before After Control Impact (BACI) design, I am collecting instream, surface, and groundwater samples to measure changes in nutrient loads resulting from a suite of BMPs implemented at a cattle grazing operation in Wallsburg, UT. ‘Before’ sampling began in April 2014 and occurred every other week through August 2014, BMPs are being implemented in September 2014, and then ‘after’ sampling will be conducted every other week from April 2015 to August 2015. I am running chemical analyses on the water samples for total phosphorus, dissolved total phosphorus, soluble reactive phosphorus, total nitrogen, dissolved total nitrogen, nitrate/nitrite, and ammonium. The results will be used towards development of locally relevant loading coefficients for theses various forms of nutrients, and also assess the success of BMPs in the intermountain west climate of Utah. Using the collected site data, I am also building a field scale, process-based model using the Soil and Water Analysis Tool (SWAT). This model will be used to determine nutrient loading coefficients for other sites within the Main Creek watershed, and also to verify nutrient loading reductions estimated in the Deer Creek Reservoir Total Maximum Daily Load (TMDL) study