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Drought 2002

Roger A. Pielke, Sr., State Climatologist, Colorado Climate Center
Reagan Waskom, Extension Water Resource Specialist, Colorado State University

The year 2002 was dry. The hot, cloudless summer of 2002 surprised many Coloradans with its relentless intensity — impacting all our lives to some degree. The three dry years preceding it had worried some, but passed unnoticed by many. Yet when our snowpack evaporated in May, reservoirs turned into dust bowls, and fires roared across the state, people started to wonder: could it get any worse?

With our complex monitoring equipment and computer analysis, this seems a simple question: was this Colorado's driest year in recorded history? The answer: it depends.

Science and Statistics
Scientists read drought's signature on the landscape through precipitation data, tree rings, soil moisture, and streamflow gauges. Historical records tell us how long other droughts have lasted, their severity, and where they hit the worst.

Certainly, in 2002 reservoir storage and river runoff were at record low levels. In a normal year, Colorado rivers carry an average of some 16 million acre feet (maf) of flowing water. According to the State Engineer's office, 2002 river flows plunged to 4 maf. Even with residential watering restrictions, farmers fallowing fields, and other water conservation measures across the state, some 6 maf of water had to be drained from the state's reservoirs just to keep taps flowing.

Snowmelt runoff is critical. Colorado receives over 80 percent of its water from spring snowmelt. Last year, by May 1 statewide snowpack was only 19 percent of average — a record low. At a time when the mountains usually release their moisture, huge bare patches devoid of snow sent water managers scurrying to recalculate their water supply predictions.

Scorching temperatures didn't help either. Above-average temperatures enhanced evaporation, snowmelt, and plant water uptake, exacerbating already dry conditions. The spring of 2002 saw the earliest recorded ice-off at Lake Granby and the earliest ever opening of Trail Ridge Road in Rocky Mountain National Park.

Precipitation throughout the rest of the summer was no less generous. Rainfall in June and July was little to zero in many areas of western Colorado. Eastern Colorado received some precipitation but it evaporated quickly with high temperatures. August saw precipitation levels still well below average statewide, although some areas of eastern Colorado received some respite with several heavy rains.

No doubt the 2002 drought was bad. Minimal snowpack, baking heat, and summer monsoons that never arrived, all made 2002 the driest year ever recorded for many areas around the state. But from a statewide perspective, it wasn't the worst we've ever seen.

Although the May 1 record low snowpack of 19 percent was much discussed, in reality it was not far below the previous record low snowpack measured on May 1, 1981, which was only 21 percent of average. Daytime temperatures were not as extreme as the Dust Bowl of the 1930s when southeastern Colorado recorded highs above 110°F. However, it is the record of total precipitation for the year that tells the interesting story.

According to state sources, total precipitation measurements collected across the state for the specific time period of September 2001 through August 2002 show that a majority, or some 60 percent of the representative monitoring stations selected, experienced their driest year ever recorded. However, evaluate the same data using the traditional water year calendar — October 2001 to September 2002 — and only 33 percent of those same sites reported their driest year on record.

Grand Lake, Meeker, Pueblo, Rocky Ford, and Akron all recorded their driest year ever. However, in the Grand Junction area, 2002 was only the 43rd driest ever. For Montrose it ranked 29th, Cheyenne Wells 9th, Kassler 6th, and 4th driest ever for Center and Leroy.

Although we do extract a certain amount of deep groundwater to supplement our need for municipal, agricultural, and other water uses, precipitation in the form of rain and snowfall provides the majority of the water the state uses: filling our reservoirs, sustaining our ecosystems, and making our rivers flow. What the 2002 climate record tells us is that we could have received less. Last year's precipitation deficit was not as extreme as it might be in the future or has been in the past.

Water Crisis
No matter how much precipitation falls within our state, another type of drought can still plunge the region into a water crisis. Called hydrologic drought, it occurs when demand exceeds supply.

Colorado's unprecedented population and development boom of the 1990s increased the state's population by some 30 percent. Lawns, golf courses, and swimming pools demanded more water.

In contrast, the farm economy stagnated. With input costs for tractors and equipment skyrocketing, intense international competition, and commodity prices that have not increased in real terms for the last 30 years, many farmers could ill afford expensive efficiency improvements to their irrigation systems. In many cases, it made better sense to sell their liquid gold to the cities.

These changes in Coloradan's land uses and lifestyles occurred during one of the longest periods of wet weather since the 1920s. From 1982 to 1997, Colorado enjoyed a string of wet springs and plentiful monsoons, while total water storage increased very little and water conservation received minimal attention.

Lulled into a sense of security by largely inexpensive and plentiful water supplies, the summer of 2002 shocked many Coloradans when they found their public swimming pools closed, their lawns and pastures brown and dusty, and their water rights so quickly reduced in priority by some of the most senior water rights in the state.

Wake Up Calls
With little water to go around, the state's prior appropriation system works cruelly well — prioritizing sparse surface water deliveries from senior to junior decrees. As water levels drop, a senior water right holder will 'call' for their water. Diversions by junior users are then reduced or shut down until the senior decree is fulfilled.

In river basins across the state, calls for reservoir releases began in April and May, when reservoirs are normally filling, not releasing. Water commissioners had to dust off some of their files as calls for water went back further in the priority system than recent memory. This ended the irrigation season early for all but the most senior diverters.

The most senior call on the South Platte River came from the 1865 Farmers Independent water right. It had not been necessary to call for this water since 1967. East of the Front Range, plains reservoirs used primarily for agricultural irrigation were virtually empty by the end of August.

In southwestern Colorado, Lemon and Vallecito reservoirs were drained by August to the point where no more water could be removed without pumping. Similarly, Denver chose to completely drain its Antero Reservoir to protect its water supply system.

On the Arkansas River, historic low flow conditions created serious water supply challenges. In an unprecedented occurrence, a more senior water right called out the City of Pueblo's emergency drought reserve water supply dating from 1874.

In the Rio Grande Basin, Water Division Engineer Steve Vandiver issued nearly 500 emergency drilling permits for farms and residences where groundwater wells, some 150 years old, went dry. The Rio Grande Water Conservation District reported a drop of 750,000 acre feet in the unconfined aquifer in the past three years, with some wells falling as much as 35 feet during the summer.

For the first time ever, none of the major reservoirs on the mainstem of the Colorado River managed to fill. As a whole, the Colorado River Basin relied on numerous cooperative agreements to make it through the year. The Shoshone Power Plant near Glenwood Springs voluntarily let some water flow by its intake structures during the spring, West Slope municipalities donated water where possible, and ExxonMobil donated 5,000 acre-feet of stored water. To preserve as much upper basin storage as possible, the Colorado River Water Conservation District compensated Redlands Water and Power to reduce their summer hydroelectric diversions and cease their use of water for power generation during the winter months.

In the Gunnison Basin, the Uncompahgre Valley Water Users Association had to call for water from the Gunnison Tunnel, curtailing water use in the Upper Gunnison Basin. The last time this call had been placed was before construction of Blue Mesa Reservoir in the 1960s.

Hit Hard
The climate record tells us that for the majority of the state, dry conditions related to last year's precipitation deficit were extreme, but not as bad as they've been in the past. This statement is perhaps most troubling when considering how hard the 2002 drought hit the state's economy. Although drought-related losses continue to accumulate, the direct economic cost to Colorado of the 2002 drought alone is estimated at $1-1.5 billion.

Agriculture was the hardest hit, with dryland farmers and ranchers feeling the effects more than any other economic sector in the state. A $5.4 billion industry in the state, agriculture suffered approximately $500 million in direct losses last year. Dry land wheat growers lost $125 million alone as yields were less than half of average. Almost 30 percent of wheat plantings had to be abandoned as worthless. Irrigated corn production was down approximately 15 percent below average, while the dryland corn crop was almost a total loss. Hay yields were about 65 percent of the 10-year average.

High hay prices helped some, but crippled many. Feed for cattle became so expensive that many producers had no choice except to sell off their entire herd. Don Ament, Commissioner of Agriculture, estimated that 40-50 percent of breeding stock (more than 200,000 head) were sold or shipped out of state during 2002.

In the cities, the landscape and horticulture industry took the brunt of strict outdoor watering restrictions. Nurseries and landscape contractors suffered as many homeowners and businesses decided not to install new plantings. Colorado's ‘green industry’ is a $2.2 billion industry supplying some 40,000 jobs. Last year, turf industry representatives reported 50 percent lay-offs of seasonal employees and laborers. Denver's former mayor, Wellington Webb, stated that tree losses and replacement costs alone would exceed $500 million.

Tourism and recreation, typically an $8.5 billion industry in Colorado, suffered a 20—25 percent decline, as river flows slowed down to a trickle and fish struggled to survive. The rafting industry was particularly hard hit, with a 50 percent decline in total sales. Outfitter's businesses were down 45 percent, a projected $25 million impact, while fishing licenses were down by 93,000, translating into a $1 million loss to the Division of Wildlife.

Fire was undoubtedly the most visible and frightening aspect of the 2002 drought, with a record 4,612 wildfires burning 619,000 acres and roughly 1,000 structures. Fire suppression alone carried a $152 million price tag. Insurance and restoration costs are estimated at an additional $100 million.

Four of the five largest forest fires in recorded Colorado history occurred in 2002, with the record breaking 137,000 acre Hayman fire garnering the full attention of Denver residents last June. People caused so many wildfires in 2002 that for the first time in state history, the U.S. Forest Service and the Bureau of Land Management declared millions of acres of federal land off-limits to the public, while fire bans were enacted across the state.

Fish suffered as low flows caused higher stream temperatures and lower dissolved oxygen levels, putting additional stress on aquatic ecosystems. At Antero Reservoir, Division of Wildlife (DOW) officials salvaged over 10,400 trout and other fish species jeopardized by Denver Water's plans to drain the reservoir. Fish traps, seines, and electroshocking were used to capture fish for transport to nearby Elevenmile Reservoir.

In the Gunnison River above Blue Mesa Reservoir, low water levels threatened the seasonal spawning of kokanee salmon. Using five gallon buckets, DOW staff and volunteers transferred over 20,000 fish to waiting trucks which transported them to the Roaring Judy Fish Hatchery. Similar stories, including rescue of isolated populations of threatened and endangered native fish, abound through the state. Other stream reaches were not so lucky, and many fish and other aquatic life were lost due to low flows and high water temperatures.

Learning and Change
Although providing just a brief snapshot of the region's history, Coloradans have been collecting climate measurements of our frequent drought periods for more than 100 years. Some of the driest conditions statewide occurred in 1894, 1910-11, 1924-25, 1935, 1953, 1977, and now 2002.

The big droughts of the past prompted significant changes in water management, policy, land use, and economic growth. This drought will be no different, although it is too soon to declare the drought over, or how we have changed.

Clearly the dry year of 2002 was severe, but not unprecedented.

Historic river calls, startling economic costs, and significant environmental impacts reflect the stresses on our resources caused by ever increasing water demands. Near the limits of our natural supplies and legal entitlements, Coloradans are increasingly vulnerable to extreme drought cycles. And no matter how much precipitation falls within our state or how much groundwater we pump, when demand exceeds supply, we can still find ourselves in a water crisis.

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