Title:         Desert Dust Impacts on Snowmelt and Hydrology in the
        Upper Colorado River Basin

            ABSTRACT

The Colorado River provides water to 27 million people in seven states and two countries but is overallocated by more than 10% of the river’s historical mean. Climate models project runoff losses of 7–20% from the basin in this century due to human-induced climate change. Recent work has shown that decreased snow albedo from anthropogenic disturbance-induced dust loading to the CO mountains shortens the duration of snow cover by several weeks, and advances peak runoff at Lees Ferry, Arizona by an average of 3 weeks.  Increases in evapotranspiration from earlier exposure of vegetation and soils decreases annual runoff by more than 1.0 billion cubic meters or ~5% of the annual average. This prior work was based on observed dust loadings during 2003-2008, however 2009 and 2010 saw unprecedented levels of dust loading on snowpacks in the Upper Colorado River basin on the order of 5 times the 2003-2008 loading. This presentation will provide an overview of dust impacts on the snow energy balance, resulting effects on snowmelt and basin hydrology, and some new results examining the hydrologic impact of extreme dust years such as 2009/2010 and interactions with projected regional warming.