WESTERN STATES WATER NEWSLETTER 8/13/04

WATER RESOURCES
Drought

According to the August 10 Drought Monitor, scattered summer thunderstorms have brought little or no relief from the drought in the Western Rockies and Far West. Here are some excerpts from the report: “The so far anemic monsoon season continued across most of Arizona, western New Mexico, Utah, and western Colorado last week. A small part of north central Arizona and adjacent Utah were the only exception. In this area, fairly widespread rains of 1 to 4 inches were reported, resulting in an improvement to [severe hydrological drought] conditions. The only other area experiencing some improvement last week was the northern tier of Washington, where unseasonably heavy rains of 1 to 3 inches...” raised the assessment from moderate to abnormally dry agricultural and hydrological drought conditions east of the Cascades.
“Across the southern tier of the West, scattered 1 to 3 inch rains fell on the higher elevations of central Arizona and in adjacent parts of southeastern Arizona and southwestern New Mexico. These rains, however, were insufficient to improve the abnormally dry to extreme drought conditions assessed last week, given that this is typically a relatively wet time of year, and considering the magnitude of the region’s multi year precipitation deficits. In fact, a small area of deterioration (to extreme drought) was assessed in south central Arizona.”
“Rainfall was sparse across the remainder of the West, with little or none falling on areas from the lower northern Intermountain West southward through the Great Basin and southwestward across most of California. While dry weeks during summer in these regions are quite common, the persistence of low relative humidity, somewhat above normal temperatures, only spotty rains, and slow but consistent surface moisture loss for the last few months has led to increased fire danger and a westward expansion of abnormally dry to extreme drought conditions across California, southern Oregon, and Nevada.”
“Multi year precipitation deficits are very large in most locations from the Rockies westward to the southern California coast, the Sierra Nevada, and the Cascades. Only 64 to 75 percent of normal precipitation has fallen on a vast majority of this large region since early August 1999. This represents at least one typical year’s worth of precipitation missing over the course of the last 5 years, with deficits approaching typical 2 year totals in much of the Intermountain West and desert Southwest. The relatively recent persistence of below normal precipitation and humidity combined with above normal temperatures has not helped the situation, with reservoir storages declining at a rate exceeding the typical climatological decline since May 1, even considering the dry summers typically observed in most of the region, according to the Natural Resources Conservation Service.”
East of the Rockies, heavy rains (4 to 6 inches) doused parts of central and northeastern Colorado while moderate amounts (1 to 4 inches) were fairly widespread across southeastern Montana, areas near and north of the Black Hills, most of eastern and parts of central Colorado, and portions of northern and eastern New Mexico. Most of these areas experienced a significant improvement in drought classification, which now range from abnormally dry to severe. In addition, drought conditions were eliminated in part of extreme eastern New Mexico, southeastern Colorado, and extreme southwestern Kansas. Other sections in the High Plains and eastern Rockies did not receive as much precipitation, thus drought classifications were unchanged from last week.
Across the Great Plains, drought conditions in North Dakota, most of Nebraska, and adjacent parts of Kansas generally remained unchanged, but moderate rains of 1 to 3 inches brought some localized improvements and similar amounts led to measurable improvements in a large part of central South Dakota, where such totals occur less frequently than they do farther south. In contrast, significant rains again evaded southcentral Nebraska, where drought classifications generally worsened. The 3 month rainfall deficits in the Great Plains region total 1-4 inches less than normal for the southwestern quarter of North Dakota, southcentral South Dakota, and parts of northcentral and southeastern Nebraska, and long term deficits remain substantial in much of the area. Over the last 5 years, between 10 and 20 inches less than normal precipitation has fallen from south central South Dakota southward through northern Kansas, with 20 to 30 inch deficits observed in central Nebraska and adjacent areas. For the central tier of Nebraska and parts of northern Kansas, this represents more than a typical year’s worth of precipitation missed since early August 1999. Farther south, widespread moderate to heavy rains (1 to 4 inches) eliminated abnormally dry conditions across the Texas Panhandle and most of western Oklahoma, but abnormally dry conditions remain in central Oklahoma, where only light rains fell last week.
The current issue of Time Magazine carries an article entitled, “Why the West is Burning.” It notes the drought could “...easily turn 2004 into one of the West’s worst fire years on record.” The August 16 issue also states, “And no one knows when the drought will end. Scientists believe this dry spell, which has plagued a broad swath of the West since 1999, is more typical of the region than its 60 million inhabitants would care to admit.... Consider, for example, the 1922 compact that determines the allocation of water from the Colorado River. Scientists have shown, by studying tree rings and other historical evidence, that the allocation was based on water flows that were the highest they had been for more than 475 years. By contrast, the flows since 1999 rank among the lowest. As a result, Lake Powell, the giant reservoir created...by the Glen Canyon Dam, stands some 60% below capacity and seems destined to fall even lower. No wonder that states like Colorado -- whose rights to that water are trumped by the rights of California, Nevada and Arizona -- are anxiously bracing for a crisis.”
The article continues, “Caught off guard, political leaders and water-resource managers have been turning to scientists for help. What do researchers know about patterns of drought in North America? What do they think occurred in the mid-1990s when a big chunk of the West abruptly veered from wet to dry? And do they believe that the current shortfall in precipitation is just a temporary dry spell or an ominous realignment of the earth’s climate system?” The article goes on to discuss tree ring and paleoclimatology research, sea surface temperatures, El Niño, La Niña, climate models, global warming and future climate variability. Professor Douglas Kenney, University of Colorado, observes, “Everyone’s pretty clear that the earth’s getting warmer, but it’s unclear just what that means. It might mean a wetter future or a dryer future. It might even mean a wetter future with no net gain.” Dr. Philip Mote, a University of Washington climatologist states, “Drought is more than a precipitation deficit.” The problem is that “...you don’t have as much water as you’d like at a given point in time.” The article concludes, “The past is an imperfect lens through which to peer into the future, but looking backward provides a glimpse, at least, of the sorts of extended dry spells that those who live in this drought-prone region today should be prepared to endure.” (J. Madeleine Nash/Sage, Time Magazine, August 16, 2004)....