Water Supply and Lake Powell

Lake Powell Reservoir: A Failed Solution

Lake Powell Reservoir was justified to Congress in the 1950s as the perfect solution to uncertainty of water supply for the growing Southwest. It was to be the “silver bullet”, providing an insurance policy for the upper basin states’ water delivery responsibility, regulating floods, and being a “cash register” hydropower dam to pay for building dozens of other dams and irrigation projects upstream in the Colorado’s watershed. After forty years, it is clear that Lake Powell Reservoir is far from the perfect solution to water supply problems in the West. It looses a significant amount of water annually to evaporation and seepage (nearly 1 Million acre-feet annually), generates an insignificant amount of hydropower, is unsafe, has all but destroyed the natural biological resources and processes in Glen and Grand Canyons, while imposing significant long-term costs on the public (due to rapid sedimentation) including loss of endangered species, cultural resources, and ecological balance of the Grand Canyon. However, the most devastating impact of Lake Powell’s development has been the false sense of water security to both the Upper and Lower Basin States. This fallacy has resulted in unsustainable growth and development. The idea of a centralized water and electricity system has simply proven to be unsustainable.

Lake Powell: Unnecessary for Water Delivery

Glen Canyon Dam was built for the primary purpose of water storage to ensure delivery of water to the Lower Basin and protect the water dowery of the Upper Basin States. The upper basin is required to deliver 8.23 million acre-feet (MAF) of Colorado River water to the lower basin and Mexico every year. This amount is a combination of water required for delivery to the Lower Basin from the 1922 Compact and the Upper Basins portion of the amount of water due to Mexico annually.

The writers of the 1922 Colorado River Compact recognized the dynamic nature of the Colorado River and based the requirement on a ten-year average to allow for annual fluctuations. The earliest official government flow records from 1906-2003, demonstrate that without Glen Canyon Dam, the upper basin would have been able to deliver the Compact required 75 MAF to the lower basin and Mexico in every single ten-year period on the record.

The Bureau’s Impractical Policy

The Bureau of Reclamation's current policy requires that 1/10 of the ten-year requirement must be delivered every year, despite the clear intent of the 1922 Compact. By adapting a management policy following the Compact's original ten-year requirement, the need for water storage in Glen Canyon would virtually disappear. Since only a negligible amount of water is withdrawn from Lake Powell, Lake Mead could regulate and store water for the use of the Lower Basin and Mexico. In fact, the lower basin has already figured out a number of options for storing its own water including natural aquifers, off-stream storage facilities and water banking.

Lake Powell: A Huge Water Waster

Due to its high desert location and huge surface area, Lake Powell loses an average of 860,000 AF of water annually to evaporation and bank seepage. Glen Canyon Dam is unnecessary and counterproductive to the water storage and delivery purposes for which it was built. Each year, enough water is wasted by the dam to supply the entire City of Los Angeles. That’s three times Nevada’s annual allotment and enough to supply the Salt Lake Valley for five years. It essentially serves as a water meter to measure the upper basin’s delivery to the lower basin, however it is a “leaky faucet” which makes delivering that water more difficult for the upper basin.

  · Lake Powell loses more than 6% of the Colorado River's annual flow -- more than three times Nevada's annual allotment.
  · Since completion of the Dam, more than 34 MAF of Lake Powell water has been lost to evaporation and bank storage.
  · The water lost is Upper Basin water: Glen Canyon Dam actually makes it more difficult to fulfill the delivery requirement of 82.3 MAF of water to the Lower Basin.


Based upon the Bureau’s own historical flow data (1906-2002), with water wasting Powell reservoir, there is a 1:1000 chance the Upper Basin would be unable to deliver the required 82.3 MAF of water. Without the water loss at Lake Powell, the odds decrease to 1:30,000.
 

The Economic Perspective

As the demand for water in the Southwest steadily grows, the utility of a reservoir that wastes nearly 1 MAF every year is suspect. In San Diego water prices, based upon the price used in the ongoing negotiations for the sale of Colorado River water by the Imperial Irrigation District to San Diego, the water lost at Lake Powell each year is worth $225 million dollars. The fair market value of the water wasted by Glen Canyon Dam is far greater than the net income from the sale of electricity produced by the dam; essentially, the "fuel" costs more than the product being produced. Since 1963, more than 34 MAF of water has been lost from Lake Powell; worth about 9 billion dollars.

A Broken Western Water Delivery System

When the Colorado River Compact was signed in 1922, the estimates of average river flow were based upon unusually wet years and water rights were distributed for non-existent water. Estimating the annual river flow at 17 million acrefeet (maf), the signers decided to play it safe and divide 15 maf among the upper and lower basins. Twenty years later, a treaty with Mexico obligated another 1.5 maf for delivery to Mexico.

More than eighty years since the Compact was signed, the average annual flow has proven to be closer to 13.5 maf. Losing another 1 maf of water at Powell reservoir and 1.5 maf of water at Mead reservoir, leaving an annual average of 11 maf of water to satisfy 16.5 maf of water allocations. The Western water delivery system is broken and it is only a matter of time before it fails completely.

Drought & Climate Change

Complicating water supply issues in the West, recent scientific studies predict the water supply in the West to be reduced drastically over the next few decades. By 2050, University of Washington scientists predict the flow of the Colorado River to decline by one third. Five years into the worst drought in centuries, many scientists who have been studying tree ring evidence say the West is actually experiencing a return to normal drier climate conditions.

In reality we may be reentering a low water period that has not been seen for the last 500 years. As climate models predict that Colorado River water supply will continue to decrease, it is imperative for the sustainability of the West that our current inefficient water delivery plumbing system be carefully scrutinized. As the most destructive and least useful, “leaky” water project ever built, Glen Canyon Dam is unsustainable and the weakest link in the outdated system. It is the duty of water managers in the West to secure a sustainable system for a sustainable society in the West.

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