Upper Rio Grande Impact Assessment

Reclamation, in cooperation with Sandia Laboratories and the U.S. Army Corps of Engineers, has released the Upper Rio Grande Impact Assessment, an investigation of the current and potential future hydrologic impacts of climate change in the Upper Rio Grande Basin of Colorado and New Mexico. The study presents a detailed evaluation of the past, current, and future climate, hydrology, and water operations, and uses a suite of modeling tools, along with reasonable assumptions about future drivers of climatic changes, to project potential impacts associated with climate change on streamflow, water demand, and water operations. The report documents that, over the period 1971 through 2011, average temperatures in the Upper Rio Grande Basin have risen at just under 0.7°F per decade, approximately double the global rate. This study projects that temperatures will continue to rise, with a projected average temperature increase of 4°F to 6°F by 2100. Although modeling projects that total annual average precipitation in the basin will not change considerably, it projects that there will be changes in magnitude, timing, and variability of precipitation and river inflows. The study projects an overall decrease in water availability, with native Rio Grande supplies projected to decrease by an average of one-third, and imported San Juan-Chama Project supplies projected to decrease by an average of one-quarter. The model simulations consistently project decreasing snowpack, an earlier and smaller spring snowmelt runoff, and an increase in the frequency, intensity, and duration of both droughts and floods.