By Christopher Peterson,
executive director
Glen Canyon Institute

A common response to the continuing drought in the West is one of alarm over water supply and the Colorado River. People have been worried about the increasingly dysfunctional Law of the River for decades. The single biggest problem with the whole water delivery system is that the Colorado River is incredibly over-allocated.

On a river that delivers an average of 13 million acre-feet (MAF) annually, compacts and agreements have legally allocated 16.5 MAF annually. Further restricting water delivery capacity, Lake Powell Reservoir and Lake Mead Reservoir combined lose more than 2 MAF annually to evaporation and bank seepage.

As water usage across the basin has grown with the population, water managers have known and expected this current "crisis" for years. The article in the Post relayed some of the drought-imposed urgency for dealing with the situation, yet neglected some key components to the complex Law of the River that should be considered when looking at the role Glen Canyon Dam plays in Colorado River water management.

First, it is important to expound on the rolling 10-year requirement built into the 1922 Compact that the Post article briefly touched on. The signers of the Compact essentially divided the water of the Colorado River between the upper and lower basins.

They recognized that the Colorado River had high and low years, so instead of requiring annual downstream deliveries by the upper basin, they based the delivery requirements on a rolling 10-year average. So, the legal requirement is 75 MAF every 10 years. The bureau's current "bookkeeping" policy to release a minimum of 8.23 MAF annually takes into account 7.5 plus the upper basin‚s 0.73 MAF Mexican water treaty requirement.

The Bureau of Reclamation justifies Glen Canyon Dam with its current policy of delivering 8.23 MAF annually. They'll tell you that with only 6 MAF of water coming down the Colorado River this year, the upper basin would default on its Law of the River requirements without the "insurance" of Lake Powell reservoir.

The Bureau will, however, neglect to mention that the huge amount of water that came downstream in the late 1990s was the "insurance" the signers of the 1922 Compact built into the Law of the River. In fact, the 1922 Compact and subsequent legislation and policy have identified the process to deal with water shortages.

The Bureau of Reclamation's own records show that the Colorado River has met the Compact's requirements as far back as the records were kept (1906) – without needing Lake Powell. That's right, the Colorado River has delivered the required amount of water downstream to the lower basin states in every single 10-year period without relying upon the "insurance" that Lake Powell's water storage is intended to give.

In essence, Lake Powell has never once been used to meet the water delivery requirements. In fact, Lake Powell actually makes it more difficult for the upper basin to meet its downstream delivery requirements.

Lake Powell loses nearly 1 MAF of upper basin to evaporation and bank seepage annually. That is enough to meet the needs of the city of Los Angeles every single year. In fact, based on the Bureau's records, the chances that the upper basin wouldn't be able to meet its downstream delivery requirement with Lake Powell is 1:1000. However, without Glen Canyon Dam, and its wasted 1 MAF annually, the chances fall dramatically to 1:30,000.

When looking at the water delivery system in the West, the temporary nature of Glen Canyon Dam is rarely considered. In pursuit of a sustainable water supply for generations in the future, it is irresponsible to neglect the role of sedimentation in the management of the Colorado River over the next century.

As one of the muddiest rivers in the world, the Colorado River delivers approximately 100 million tons of sediment into Lake Powell reservoir every year. That's the equivalent of 30,000 dumptruck loads every single day.

The recent article cited Powell reservoir's storage capacity at 24.3 MAF, but neglected to mention that more than 3 MAF of sediment has decreased the storage capacity by 9 percent in 40 years, and the deposits in the reservoir continue to grow. The sediment deposits are projected to render the dam unsafe within 100 years. This pesky side effect of storing water behind Glen Canyon Dam has yet to be carefully studied. It seems like it may be a good idea to learn more about this growing problem.

In reality, the Bureau of Reclamation has done remarkably little to study the impacts of Glen Canyon Dam on the water delivery system of the Colorado River. While the Grand Canyon Protection Act required studies on downstream ecological impacts of the dam in Grand Canyon, the overall Colorado River system has never been scrutinized for efficiency.

With wide agreement that the Law of the River is outdated and dysfunctional, and with the drought further stressing the broken water delivery system in the West, it is time to study how to make the system more efficient and sustainable.

Every single gallon of Colorado River must be publicly scrutinized and a plan to "fix" the broken water delivery system and achieve a sustainable water supply must be initiated now.

A Colorado River system-wide Environmental Impact Statement should be undertaken immediately to force the current wasteful water management policies to be carefully examined and improved.