The Upper Colorado River Basin is experiencing a protracted multi-year drought which began in October 1999. Lake Powell was essentially full during the summer of 1999 with reservoir storage at 97 percent of capacity. However, it became evident with the low precipitation totals of October, November and December, at only 30 percent of average, that the stage was set for the first year of low runoff which occurred in 2000.

Inflow to Lake Powell provides a useful barometer of drought conditions in the Colorado River Basin. In the late 1990’s, inflow to Lake Powell was above average and the lake stayed full from 1995 through 1999. As late as September 1999, Lake Powell was still 95 percent full. Inflow into Lake Powell from water years 2000 through 2004 was about half of what is considered average. The 2002 inflow was the lowest ever recorded since Lake Powell began filling in 1963.

Lake Powell reached a low elevation on April 8, 2005 at 3,555 feet (145 feet from full pool), with reservoir storage at 33 percent of live capacity. The last time Lake Powell had been this low was in May 1969. Through the spring and early summer of 2005, the water surface elevation increased reaching a peak elevation of 3,608.4 feet on July 14, 2005.

Hydrologic conditions in the Colorado River Basin improved in water year 2005 (October 2004 through September 2005). The elevation of Lake Powell increased by 31 feet and water storage in Lake Powell increased by 2.77 million acre-feet. Unregulated inflow to Lake Powell in water year 2005 was 105 percent of average. Unfortunately in 2006, drier conditions resumed in the Colorado River Basin. Unregulated inflow to Lake Powell in water year 2006 was only 73 percent of average. Over the past seven years, (2000 through 2006, inclusive) inflow to Lake Powell has been below average in all but one year (2005). While drought conditions eased in 2005, below average inflow in 2006 and the projected below average inflow in 2007demonstrate the protracted nature of the drought in the Colorado River Basin.

Current Conditions and Projections - APRIL 2008

Hydrologic conditions above Lake Powell have dried out somewhat during March.  Precipitation in the Upper Colorado River Basin was 65 percent of average in March 2008 and is now 112 percent of average for the water year as of April 7, 2008.  As of April 7, 2008 the snowpack conditions above Lake Powell are 116 percent of average.  The climate outlook for the Upper Colorado River Basin indicates that the next three months will likely have below normal precipitation and above normal temperatures.

Inflow to Lake Powell is currently 14,500 cfs (April 6, 2008). Total unregulated inflow to Lake Powell so far in water year 2008 (October through March) is 86 percent of average with March measured at 88 percent of average.

Forecasted April through July unregulated inflow to Lake Powell in 2008 is 9.7 million acre-feet, 122 percent of average (April final forecast).  Typically by April 1st, the snow accumulation season is nearly complete in the Upper Colorado River Basin.  Snowpack levels, on average, peak by about April 10th.

The current elevation of Lake Powell (March 2, 2008) is 3,590.5 feet, 109.5 feet from full pool elevation of 3,700 feet. Reservoir storage is currently 10.86 million acre-feet, or 44 percent of capacity. The water surface elevation of Lake Powell is now near its seasonal low. In April, anticipated snowmelt runoff will cause the water surface elevation to begin to increase. Under the current inflow forecast, Lake Powell would reach a peak elevation of about 3639 feet in July 2008. The peak elevation for Lake Powell in 2007 was 3,611.7 feet.

How Lake Powell Functions

It is important to understand that to provide for the water and power needs of the Southwest, Lake Powell functions essentially as a bank account of water that is drawn upon in times of drought. In 1922, the Colorado River Basin States signed the historic Colorado River Compact. Under the Compact, the states of Colorado, Utah, New Mexico and Wyoming received an entitlement to use 7.5 million acre-feet (MAF)of Colorado River water per year. The Compact also requires that these states deliver 75 MAF over any ten-year period at Lee Ferry (16 river miles below Glen Canyon Dam) for use by the downstream states of Arizona, California, and Nevada. Without the bank account of water stored in Lake Powell, water users in Colorado, Utah, New Mexico and Wyoming might have to curtail uses during periods of drought to meet this delivery requirement. Instead, storage in Lake Powell is used resulting in lower storage levels during periods of drought. The system is designed to function this way, and it is working well. There have been water shortages caused by the drought in the Upper Colorado River Basin the past five years (particularly in 2002), but water users above Lake Powell have not had to curtail use to meet deliveries to water users in the Lower Colorado River.

The Colorado River system of reservoirs was designed to protect against drought. Inevitably however, there are impacts associated with droughts, particularly when the drought is severe as is the current drought. While most marinas remain open, reservoir recreation has been impacted as well as downstream whitewater rafting. Additionally, there have been water shortages to water users in the Upper Colorado River Basin in the past five years, (particularly in areas where there is limited reservoir storage), and power generation has also been affected.

No one can say with certainty when this drought will end. River flow records of the Colorado River Basin reveal significant variability during multi-year periods of above and below average river flows. Inevitably, there will be a shift to wetter hydrologic conditions with an end to this drought and a recovery to water storage in Lake Powell.

Drought is a normal part of natural climate variations. There is nothing unusual about the occurrence of a drought, which should not be confused with aridity. Droughts are merely temporary abnormalities determined by deficient precipitation and depend on the area in question. In one area of the world a drought may be a week without rain, while in drier parts of world like the American Southwest, it might be an annual rainfall deficit of less than four inches.

A drought is also defined by its effect on the intended use of the water. Often, the the impacts of a drought are exacerbated because of increasing demands on a limited supply of water. Recent well documented droughts around the world have resulted in significant economic and environmental impacts.

Droughts have occurred frequently throughout history. Whether or not a drought exists is determined by comparison with “normal” hydrology for an area. Normal is defined as a long-term average of highs and lows, which may include droughts and extremely wet periods. No single year will ever be normal due to the shear complexity of weather patterns. Because the occurrence of a drought affects this average, the definition of normal for the American Southwest, will be altered for the next several decades.