June 9, 2004

The state of Colorado rode a climatological see-saw during March, April and May 2004 as the state remained far from recovering from multi-year drought conditions, according to climate experts at Colorado State University. March was one of the driest months in Colorado history, while above-average precipitation fell in April followed by several storms in early May.

Yet by mid-May, overall precipitation, according to state climatologist Roger Pielke, remained below average and high-country snowpack levels were low and quickly depleting, making water-use efficiency key as summer approached.

With Colorado in the seventh year of drought conditions, it remained unlikely the state would recover from the prolonged dry period this year.

Colorado would need unprecedented, almost unrealistic widespread amounts of rain to see a complete statewide recovery said Pielke. “Since the state is in a multi-year period with below-average precipitation, communities need to continue to be efficient in water use, a policy that should always be applied in this semi-arid state,” he said.

Warm weather during the first half of May resulted in early runoff and evaporation of some of the increased snowpack generated from April storms. On May 1, on a statewide basis, Colorado’s snowpack was boosted to 68 percent of average for the date (last year snowpack was 87 percent of average) and 78 percent of last year. By May 17, the snowpack had melted to 43 percent of average and 51 percent of last year, according to the U.S. Department of Agriculture’s Natural Resources Conservation Service.

The snowpack in the South Platte River Basin, a Denver water source, dropped from 65 percent of average on May 1 to 52 percent on May 17. In the Arkansas River Basin, where several other Front Range cities draw water, the snowpack dropped to 58 percent of average. The Colorado River Basin, which supplies states throughout the West, was reduced to 37 percent of average.

“Snowpack levels are important in Colorado because snowpack provides much of the water in the state’s rivers, streams and reservoirs. Eight major Colorado river systems also provide water to 10 western states,” said Pielke. “If Colorado does not receive additional significant summer rains and these snowpack levels continue to decrease at a rapid rate, the state could be facing serious late-summer drought conditions, including a heightened fire risk.”

Individual Colorado basin totals as of May 17 as reported by the NRCS follow.

Yampa and White Basin	36 percent of average	36 percent of 2003’s snowpack.
Colorado Basin	37 percent of average	32 percent of 2003’s snowpack
Gunnison Basin	56 percent of average	71 percent of 2003’s snowpack
San Juan, Animas, Dolores, San Miguel basins	60 percent of average	155 percent of 2003’s snowpack.
Rio Grande Basin	48 percent of average	164 percent of 2003’s snowpack
Arkansas Basin	58 percent of average	69 percent of 2003’s snowpack
South Platte Basin	52 percent of average	45 percent of 2003’s snowpack

Reservoir storage totals as reported by the NCRS varied throughout the state but overall were below average — yet well above where they were in May 2003. In early May 2004, statewide reservoir storage was 84 percent of average and 139 percent of the previous year.

Broken down by individual basin, reservoir storage totals follow.

Yampa and White Basin	97 percent of average	83 percent of 2003 storage
Colorado Basin	89 percent of average	211 percent of 2003 storage
Gunnison Basin	111 percent of average	135 percent of 2003 storage
San Juan, Animas, Dolores, San Miguel basins	85 percent of average	130 percent of 2003 storage
Rio Grande Basin	54 percent of average	91 percent of 2003 storage
Arkansas Basin	53 percent of average	120 percent of 2003 storage
South Platte Basin	81 percent of average	128 percent of 2003 storage

This article is based on a news release from Colorado State University.

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.