Threat of serious multi-year Colorado drought looms
February 10, 2003
Despite decent snowfall in Colorado's high country this winter, researchers from Colorado State University's Colorado Climate Center warned about the increasing threat of an exceptionally dry winter, extending Colorado's existing, two-year, state-wide drought into a prolonged, multi-year drought.
Consequently, the state's water managers and citizens should prepare for ongoing serious drought conditions at least throughout 2003, researchers warned.
"Following three years of drier-than-average conditions, the 2002 drought was serious in terms of low precipitation and diminished water supply, and while Colorado experienced very intense drought conditions during the last growing season, it was an average drought for most parts of the state," said Colorado State atmospheric science professor and state climatologist Roger Pielke Sr. "However, with the continuing lack of precipitation this winter, we are now recognizing that Colorado is entering into a serious multi-year drought," said Pielke.
CSU researchers said that the 20 years ending in 1999, during which Colorado experienced massive growth and a dramatic increase in municipal water demand, was the longest drought-free period in Colorado, and wetter-than-average based on historical data.
"We live in a semiarid region and are always on the edge of drought," said CSU climate center research climatologist Nolan Doesken. "Many people were lulled into complacency as a result of greater-than-average precipitation during the 1980s and 1990s," he said.
Pielke and Doesken suggested water conservation and water-use efficiency measures should be continued throughout the winter months. For the long term, the climatologists recommended that Colorado's water managers and communities work together to develop effective plans for long-term irrigation and municipal water use.
January 2003 proved to be one of the driest on record at several locations in Colorado, and many parts of the state witnessed warmer-than-average temperatures that promoted early snow melt and an increased rate of evaporation.
"Due to the current drought situation, and the state's water supplies already being so low, the lack of precipitation in January is making it even less likely that Colorado will quickly recover from the current drought," said Pielke. "Additionally, because of the cumulative effect from the 2002 drought, Colorado is at even more risk today than at this time last year," he pointed out.
Many of the effects of last year's drought will last several years, even if precipitation returns to average or above average for the remainder of 2003. The CSU climatologists suggested that making up the current water supply deficit in the next one to two years is unlikely.
Members of the state drought task force agree, and recently predicted that 2003 will be no better and might even be worse than 2002, meaning Colorado citizens will likely face continued water restrictions and potential wildfires due to parched conditions and timber-dry forests.
Snowpack shortfalls in early 2003
Colorado's snowpack is critical because it provides the majority of Colorado's year-round water supply, melting into rivers, streams and reservoirs.
The January Colorado Water Supply Outlook, performed by the U.S. Department of Agriculture's Natural Resources Conservation Service, indicated that a below-average snowpack was measured statewide for the sixth consecutive year. Dry soils and well-below-average reservoir storage across the state added to water concerns. Snowpack data collected through the NRCS network showed that Colorado's statewide snowpack was 85 percent of average on Jan. 1, 2003. On the bright side, snowpack was 131 percent of January 2002 snowpack.
Despite this, however, the NRCS noted that the carryover effects of the 2002 drought leaves the state "in a similar situation as last year at this time," and suggested that all feasible water conservation measures be considered.
Conditions worsened during January 2003 as the NRCS's Feb. 1, 2003 report noted sizeable decreases in snowpack percentages, leading to significantly less streamflow forecasts. The statewide snowpack percentage dropped to 71 percent of average. The NRCS reported that 140 percent of average snowfall for February and March 2003 would be needed to bring Colorado's snowpack to average by April 1, 2003.
Reservoir storage
According to CSU, Colorado's statewide reservoir storage has been below normal since September 2001. Statewide storage, reported the NRCS, was 52 percent of average as of Feb. 1 2003. The 2002 drought greatly impacted reservoir storage, and the NRCS said little hope remained for significant improvements in 2003.
Much of the precipitation that falls this winter, said CSU researchers, will be absorbed by the extremely dry soils and will replenish shallow aquifers before running into already low reservoirs.
According to the Colorado Division of Water Resources January 2003 water supply conditions update, stream flows continue to be significantly below average, and with snowpack also below average, stream flow forecasts are for a below-average runoff. The division suggested that it would be prudent for water users to at least make plans for another year of low runoff in 2003.
Climate history has shown that March through early June precipitation is often effective in a recovery from drought in several parts of the state. Optimists are also pinning their hopes on a little help from the ongoing El Niño event. But if the coming months do not provide several widespread, long-duration precipitation events, the drought will continue to worsen.
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