Drought Conditions in Utah During 1999-2002: A Historical Perspective Soda Springs Introduction 2001, to September 30, 2002): Colorado River Smiths Fork near RiverBear near Cisco, San Juan River near Bluff, and 114° IDAHO Lake Border, Wyoming ° 42° 109 Bear Green Virgin River at Virgin. At two other gages in “When the well is dry, we learn River WYOMING River Logan eastern Utah, Whiterocks River near Whiterocks the worth of water” - Ben Franklin, Bear Green River Evanston Ogden Flaming and Green River near Green River, 2002 was from Poor Richard’s Almanac, 1733 Web Gorge er R Reservoir Great Fork the second driest year on record. Streamflow iv Blacks Salt e r Lake Weber River near Oakley Jordan Salt in the Upper Colorado River Basin has been so River Utah’s weather is prone to extremes—from Lake D City u c h low that the water surface of Lake Powell is severe flooding to multiyear droughts. Five es neR Provo iv Whiterockse River White COLORADO predicted to be 80 feet below the fill level by Utah r major floods occurred during 1952, 1965, 1966, near Whiterocks Lake River r e January 2003 (Bureau of Reclamation, 2002). v 1983, and 1984, and six multiyear droughts i R P n The water level of Lake Powell is currently e NEVADA r occurred during 1896-1905, 1930-36, 1953-65, i e ce r R G iv (2003) low enough near Hite Marina (at the 1974-78 (U.S. Geological Survey, 1991), and UTAH er M u Green River upstream end of the lake) that much of the d more recently during 1988-93 and 1999-2002. Sevier r d at Green River e r y v e Lake i v R i C R r riverbed of the Colorado and Dirty Devil Rivers (Dry) r r e Colorado River The areal extent of floods generally is limited e ie e v v k Se near Cisco a e D i is exposed, as are the deltaic sediments that have B r in size from one to several watersheds, whereas F r ty re ve D River mont Ri e Beaver River v i been deposited since the lake began filling in l droughts generally affect most or all of the state. near Beaver R i v e r 1963 (fig. 2). Southern Utah, in particular the Virgin River a Esc lante Ri Colorado ve The adjacent states of Colorado, Arizona, drainage basin, began experiencing drought Cedar City r Sa iver and New Mexico also have been experiencing conditions during the winter of 1998-99. By n Rive n n R rgi r Jua Vi Virgin River near Virgin extreme drought conditions and the negative 2000, drought conditions were evident St George 37° San Juan River ARIZONA Lake near Bluff impacts that result. Record-sized forest fires throughout all of Utah. The current drought Powell during the summer of 2002 in Arizona and (1999-2002) is comparable in length and 0 20 40 60 MILES EXPLANATION 0 20 40 60 KILOMETERS Colorado were directly related to the extremely magnitude to previous droughts; however, with Streamflow-gaging station population growth and increased demand for Observation well dry conditions. water in Utah, the general effect is more severe. Figure 1. Location map of selected Precipitation During 2002, the fourth straight year of streamflow-gaging stations in Utah and Precipitation directly affects streamflow. nearly statewide drought conditions, some areas Wyoming. Under normal precipitation conditions, Utah of Utah experienced record-low streamflows. receives less precipitation than every other state Several record-low streamflows occurred in streamflow-gaging stations for comparison of except Nevada. Average annual precipitation at streams with records dating back to the 1900s. hydrologic conditions in Utah (fig. 1). Three of Salt Lake City is about 16.5 inches, and The U.S. Geological Survey (USGS) uses these gages registered new record-low annual precipitation statewide ranges from about 5 streamflow data from eight long-term streamflows for water year 2002 (October 1, Colorado State Route 95 bridge River Dirty Devil River Hite Exposed river delta Lake Powell Figure 2. Lake Powell near Hite, Utah, showing exposed channel of the Colorado and Dirty Devil Rivers, which are normally flooded by the lake, as well as the deltaic sediments that are deposited at the upper end of the lake; view to east in October 2002. U.S. Department of the Interior USGS Fact Sheet 037-03 U.S. Geological Survey April 2003 6 pressure ridges can dominate over the Western United States and push storm systems northward. These persistent high-pressure ridges result in 4 decreased snowfall in Utah mountain ranges (U.S. Geological Survey, 1991). Mountain 2 snowpacks have generally been below normal statewide since the winter of 1998-99, and Utah has experienced significant reductions in spring 0 runoff since 2000. Many Federal and State government agencies use the Palmer Drought Severity Index -2 INDEX VALUE (PDSI) to classify and assess long-term meteorological droughts (Hayes, 2002). The PDSI drought index responds to abnormally wet -4 or dry weather conditions and classifies the conditions on a scale from -6 to 6. On this scale, -6 -4.0 or less signifies extreme drought conditions and 4.0 or more signifies extremely wet conditions. Summarized data from the Utah 1895 1905 1915 1925 1935 1945 1955 1965 1975 1985 1995 2002 State University Climate Center in Logan, Utah Figure 3. Palmer Drought Severity Index for Utah, 1895-2002. (Donald Jensen, written commun., 2002), illustrates the variable nature of precipitation in inches on the Great Salt Lake Desert to about thunderstorms with moisture originating from Utah (fig. 3). On the basis of the PDSI 60 inches in the highest mountains (Butler and the Gulf of Mexico. classification scale, the droughts of 1988-93 and Marsell, 1972). Three types of moisture- Pacific frontal storms generally produce 1999-2002 are severe to extreme, but conditions producing weather systems generally account winter mountain snowpack, and the subsequent are not as dry as those during 1896-1905 (fig. for most precipitation in Utah: Pacific frontal spring snowmelt increases river flows and 3). systems, dissipating tropical storms, and summer reservoir levels. During some winters, high- 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 12,000 350 Colorado River near Cisco, UT Virgin River near Virgin, UT Average annual 10,000 1914-2002 average annual Average 300 1910-2002 average annual streamflow streamflow 5,297,000 acre-feet annual streamflow 144,000 acre-feet streamflow 250 8,000 No data 200 for this 6,000 period 150 4,000 100 2,000 50 0 0 200 250 Smith's Fork near Border, WY 175 Whiterocks River near Whiterocks, UT Average 200 1943-2002 average annual 150 1930-2002 average annual annual streamflow 139,500 acre-feet streamflow 81,900 acre-feet streamflow 125 150 100 75 100 Average annual 50 50 streamflow 25 0 0 10,000 350 Average Weber River near Oakley, UT Average Green River near Green River, UT 300 8,000 1906-2002 average annual annual 1905-2002 average annual annual streamflow 4,463,000 acre-feet streamflow 250 streamflow 158,500 acre-feet streamflow , IN THOUSANDS OF ACRE-FEET IN THOUSANDS OF , 6,000 200 4,000 150 100 2,000 50 0 0 5,000 100 STREAMFLOW San Juan River near Bluff, UT Beaver River near Beaver, UT Average 4,000 1916,1928,1930-2002 average annual 1915-2002 average annual annual Average streamflow 1,638,000 acre-feet 75 streamflow 37,680 acre-feet streamflow annual 3,000 streamflow 50 2,000 25 1,000 0 0 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 Figure 4. Relation of annual streamflow to average annual streamflow for the period of record. Table 1. Chronology of major and other memorable floods and droughts in Utah, 1884-2002 Flood or Date Area affected Remarks drought Flood July 4, 1884 Colorado River Probably snowmelt combined with rainfall. Drought 1896-1907 Statewide Regional. Flood Aug. 13, 1923 Tributaries to Great Salt Lake between Ogden and Salt Locally intense thunderstorms. Deaths, 7; damage, Lake City $300,000. Drought 1930-36 Statewide Regional. Flood Apr. 28-June 11, 1952 Strawberry, upper Price, upper San Rafael, Ogden, Weber, Melting of snowpack having maximum-of-record water Provo, and Jordan Rivers; Blacksmith and Spanish Fork; content for Apr. 1. Disaster declared. Deaths, 2; damage, upper Muddy and Chalk Creeks $8.4 million. Drought 1953-65 Statewide Regional. Flood June 16, 1963 Duchesne River Dam failure. Flood June 10-11, 1965 Ashley Creek and other streams between Manila and Three days of intense rainfall on thick snowpack above Vernal, and west of Manila altitude of 9,200 feet. Deaths, 7; damage, $814,000. Flood Dec. 6-7, 1966 Virgin and Santa Clara Rivers Four days of light to intense rainfall of as much as 12 inches. Damage, $1.4 million. Flood Aug. 1-2, 1968 Cottonwood Wash and other nearby tributaries to San Locally intense thunderstorms following 11 days of rainfall. Juan River Damage, $34,000. Flood Sept. 5-7, 1970 San Juan River and tributaries from McElmo Creek to Record-breaking rainfall. Deaths, 2; damage, $700,000. Chinle Creek Flood Aug. 27, 1972 Vernon Creek Locally intense thunderstorms. Drought 1974-78 Statewide Regional. Flood Apr. 10-June 25, 1983 Lower Duchesne and Jordan Rivers and tributaries Rapid melting of snowpack having maximum-of-record (including Spanish Fork); upper Price, Bear, Sevier, and water content for June 1.