Runoff conditions in Utah for water year 2011

Abstract

In May 2011, the snowpack conditions in the mountains of central and northern Utah had emergency planners and water managers preparing for levels of runoff similar to the record year of 1983. The SNOwpack TELemetry (SNOTEL) records from the Natural Resources Conservation Service (NRCS) reported that the amount of water contained in the snowpack in May 2011 was greater than it was in either May of 1983 or 2005. Despite the above average snowpack,which lasted into the summer of 2011, runoff from snowmelt in 2011 did not create the widespread damage observed in 1983 and 2005. Cooler than normal temperatures resulted in slower snowmelt rates, which produced a prolonged and elevated runoff. Annual streamflow for water year 2011 was well above average, but few records of peak streamflow were set. The increase in water-surface elevation of Great Salt Lake was also above average. Ten streamgages in central and northern Utah, with records spanning greater than 20 years, have been selected to highlight the runoff conditions in Utah during water year 2011. Streamflow on the Duchesne River near Randlett, Utah, and on the Bear River near Utah-Wyoming state line is affected by several upstream diversions. These two streamgages were included in the analysis because their streamflow records have shown responses to spring snowmelt. The annual streamflow in all 10 of these streamgages was greater than 150 percent of average, and 3 streamgages set new records for total annual streamflow in water year 2011. One streamgage set a new peak streamflow record.