According to researchers at the Colorado Climate Center at Colorado State University, the state could witness water shortages this year unlike anything residents have experienced in 25 years.
The state’s lowest snowpack accumulations in decades preceded by several years of below-average precipitation followed by a dry spring contributed to this year’s lower than normal reservoir storage, low stream flows and extremely dry soils. The summer’s monsoon moisture could help reduce short-term needs but will not likely have a large impact on Colorado’s drought situation.
"What really stands out with this year’s drought are the extremely low snowpack levels combined with the lack of reservoir storage in several basins," said state climatologist and professor of atmospheric sciences Roger Pielke Sr. "It will take an exceptionally wet summer to make much of an impact on this year’s drought."
By June, only two of the state’s 86 measurement sites had snow remaining, leaving Colorado’s statewide snowpack at 2 percent of average. Snowpack across most of the state melted during the later half of May, approximately two months earlier than usual. In many parts of the state the snow melt was absorbed by dry ground before making it to streams. Snow melt was also hampered by windy days and low humidities resulting in a substantial loss of water to sublimation.
According to the Natural Resources Conservation Service, May marked the ninth consecutive month of below average precipitation leaving statewide totals at 34 percent of average. Southwestern Colorado continues to report the lowest precipitation accumulations.
Early water demands, along with below average inflows, contributed to a substantial decrease in Colorado’s reservoir storage over the last month. Statewide storage decreased from 86 percent of average on May 1 to 73 percent of average on June 1. The combined San Juan, Animas, Dolores and San Miguel basins reported the lowest average storage at 57 percent. Other basins with below average storage include the Rio Grande at 64 percent, the Arkansas at 66 percent and the Colorado at 69 percent. The state’s best storage is in the Gunnison basin which is reporting 95 percent of average.
According to the Colorado Division of Water Resources, reservoirs are also being used earlier than average this year to meet irrigation demands. Some reservoirs could be empty by the end of the summer without significant summer rainstorms.
A dry May brought additional decreases to the already low streamflow forecasts across Colorado. According to the Colorado Drought Task Force, statewide streamflow forecasts include extremely below average (25 percent to 50 percent of normal) for the majority of northern and central Colorado river basins, and exceptionally below average (0 percent to 25 percent of normal) for the remainder of central Colorado and most of southern Colorado.
The lowest streamflow forecasts are in the San Juan River Basin with projected inflow into Navajo Reservoir at 9 percent of average. Forecasts along the Dolores, Mancos, Rio Grande and lower Arkansas tributaries remain only in the teens for percentage forecast. The state’s best outlook is in the tributaries of the upper Colorado River and the northern tributaries of the South Platte River where forecasts call for volumes of 40 percent to 47 percent of average.
According to the NOAA Climate Prediction Center’s U.S. Seasonal Drought Outlook report updated June 13, dry weather pushed fire indices into the very high to extreme range throughout Colorado. NOAA reports that all of Colorado is in a drought.
"The most dramatic and visible evidence of drought for forested areas was realized and put on national and international display," said Nolan Doesken, research associate at the Colorado Climate Center. "The rapid spread of the fires last week was indeed indicative of the widespread drought conditions that we face."
The Colorado Climate Center, housed in Colorado State University’s Department of Atmospheric Science, provides information and expertise on weather and climate patterns for the state of Colorado. Pielke and Doesken issue mid-month Colorado drought advisories throughout the spring and summer in conjunction with the center’s new Web site at http://ccc.atmos.colostate.edu that provides access to current drought, weather and other climate data.