Horsburgh, J. S., D. K. Stevens, D. G. Tarboton, N. O. Mesner, A. Spackman Jones, and S. Gurrero (2009) Monitoring data collected within the Little Bear River Experimental Watershed, Utah, USA, Utah State University.
Utah State University is conducting continuous monitoring within the Little Bear River watershed of northern Utah, USA to investiage the use of surrogate measures such as turbidity in creating high frequency load estimates for constituents that cannot be measured continuously.
Discharge, Water Quality, Pollutant Loads, Continuous Data, Surrogate Measures, Oxygen Dynamics, Hydrochemical Response
We are examining short-term variability in discharge, water quality, and pollutant loading within the Little Bear River, which drains a mixed agricultural, range, and forested watershed in northern Utah, USA. Within the Little Bear, extensive hydrologic modification for agricultural irrigation has taken place, and both point and nonpoint pollutant sources have contributed to water quality degradation. High frequency discharge and water quality data (temperature, dissolved oxygen, pH, specific conductance, and turbidity) have been collected at seven sites located throughout the watershed and that represent the range of conditions, from relatively pristine in the upper portion of the watershed to highly impacted by hydrologic modification and pollutant loading near the river’s mouth. Periodic and storm event samples for phosphorus and total suspended solids (TSS) have also been collected at each of the sites, and synthetic time series of phosphorus and TSS concentrations have been constructed at two sites using surrogate relationships between continuously measured turbidity and periodically measured phosphorus and TSS concentrations. We are examining the site-to-site variability in hydrologic and hydrochemical response, including the magnitude and timing of phosphorus and TSS loads, with changes in both spatial and temporal scale and are investigating: 1) the structure and function of the Little Bear River watershed; 2) the effect of land use and hydrologic modification on water quality; and 3) the application of high frequency data versus conventional monitoring data for water quality assessment
The Little Bear River in northern Utah, United States is typical of many semi-arid watersheds in the western United States where stream discharge is dominated by spring snowmelt runoff and where extensive hydrologic modification for agricultural diversion has taken place. The Little Bear River is a part of the larger Bear River system and terminates at Cutler Reservoir, a shallow, eutrophic reservoir built on the mainstem of the Bear River, which ultimately drains to the Great Salt Lake. The Little Bear River watershed encompasses approximately 740 km2 of primarily agricultural and forest lands. Approximately 70% is grazing land and forest, 19% is irrigated cropland and 7% is dry cropland. The area is experiencing rapid population growth, with a 32% increase in population between 1990 and 2000. Elevation in the watershed ranges from 1,340 m to over 2,700 m and most of the annual precipitation falls as snow at higher elevations, with occasional summer storms. A reservoir traps high mountain runoff in the East Fork, and another reservoir is located below the confluence of the branches of the river. In both cases, these reservoirs release water during the summer irrigation season, which generally spans from mid April to late September, to satisfy agricultural diversions that essentially dewater portions of the river below the reservoirs during much of the irrigation season.
The Little Bear River watershed of northern Utah, USA. Seven stream monitoring sites have been installed at sites located throughout the watershed, along with 4 continuous weather and soil monitoring stations.
Data collection began with turbidity and discharge at two stream monitoring sites in the summer of 2005. Five additional stream monitoring sites and two weather stations were installed during the summer of 2007. Periodic and storm event samples for total phosphorus and total suspended solids began at two sites in 2005. Sample collection continues now at all seven stream sites with weekly samples during runoff periods and biweekly samples during base flow periods. Two additional weather stations were installed during the summer of 2009 (for a total of 4), along with soil moisture sensors at each of the 4 weather stations.