Revision as of 10:43, 25 May 2017

Summary

Natural, Historic, Economic, Regional, and Political Framework

7-1 Geography of the Colorado River Basin

The Colorado River is a 1,450-mile river with its headwaters in the Rocky Mountain National Park in Colorado. The Colorado River Basin drains an area of 246,000 square miles, including parts of seven U.S. states (“Basin States”) and two Mexican states.

Figure 1. Colorado River Basin. Source: https://www.usbr.gov/lc/region/programs/crbstudy.html

The Upper Basin refers to Colorado, New Mexico, Utah, Wyoming, and includes part of Arizona within and from which waters naturally drain into the Colorado River system above Lees Ferry. The Lower Basin includes Arizona, California, Nevada, and parts of the states of New Mexico and Utah within and from which waters naturally drain into the Colorado River system below Lees Ferry. Two thirds of the flow from the Colorado and its tributaries is used for irrigation, and the remaining third is used for urban supply, evaporates into the atmosphere, or provides water to vegetation along the river. In the Lower Basin, Arizona and California use the water for irrigation and domestic uses while Nevada uses the water only for domestic purposes. Today, the Basin supplies water to 17 million people in the Southwest and Mexico. The table below shows the allocation of water from the Colorado River Basin to the seven Basin States and Mexico.

Allocation of water from the Colorado River Basin to the seven Basin States and Mexico

7-2 Lake Powell and Lake Mead

In 1966, the 710-foot concrete arch of the Glen Canyon Dam formed Lake Powell, with a capacity of 27 MAF. This dam can provide up to 1,320 megawatts of hydroelectric power at the Glen Canyon Powerplant. In the U.S., Glen Canyon Dam is surpassed only by the Hoover Dam 300 miles away, which rises 726 feet. Hoover Dam, completed in 1936, formed Lake Mead, which is the largest reservoir in the U.S. with an estimated capacity of over 31 MAF.

7-3 Timeline of Key Events and Legislation {

Issues and Stakeholders

Low reservoir elevations caused by drought threaten water allocations. How can States prepare for low-elevation reservoir conditions?

Low reservoir elevations caused by drought threaten water allocations. How can States prepare for low-elevation reservoir conditions?

Low reservoir elevations caused by drought threaten water allocations. How can States prepare for low-elevation reservoir conditions?

Analysis, Synthesis, and Insight

No ASI articles have been added yet for this case

Key Questions

Transboundary Water Issues: What mechanisms beyond simple allocation can be incorporated into transboundary water agreements to add value and facilitate resolution?

The Interim Guidelines looked beyond allocation and provided additional mechanisms for the storage and delivery of water in Lake Mead to increase flexibility of meeting its water needs. Specifically, it incentivized conservation efforts and storage of unused allocations in Lake Mead to maintain its elevation via creation of a legal construct called “Intentionally Created Surplus” (ICS) water.

Transboundary Water Issues:

What kinds of water treaties or agreements between parties can provide sufficient structure and stability to ensure enforceability but also be flexible and adaptable given future uncertainties?

Framing a new agreement to include specific water allocations to parties under a variety of scenarios can ensure resilience of an agreement through uncertain futures. One expert described a “new era” of the Colorado River in which the future hydrology “cannot be reasonably estimated by simply using the available gauge record.” Basin States “acknowledged the potential for impacts due to climate change and increased hydrologic variability” and collaborated on scenario planning in response. The 2007 Interim Guidelines defined specific deliveries to each Basin at stepped storage elevations of the reservoirs. Cognizant of the highly uncertain water supply in the Basin, the Guidelines defined allocations which addressed surplus, normal, and shortage conditions. The Guidelines included further protection from shortage by giving the Secretary of the Interior the authority to take additional necessary actions at critical elevations to avoid Lower Basin shortage as the conditions approach thresholds.

Transboundary Water Issues: What mechanisms beyond simple allocation can be incorporated into transboundary water agreements to add value and facilitate resolution?

The Interim Guidelines looked beyond allocation and provided additional mechanisms for the storage and delivery of water in Lake Mead to increase flexibility of meeting its water needs. Specifically, it incentivized conservation efforts and storage of unused allocations in Lake Mead to maintain its elevation via creation of a legal construct called “Intentionally Created Surplus” (ICS) water.

Transboundary Water Issues:

What kinds of water treaties or agreements between parties can provide sufficient structure and stability to ensure enforceability but also be flexible and adaptable given future uncertainties?

Framing a new agreement to include specific water allocations to parties under a variety of scenarios can ensure resilience of an agreement through uncertain futures. One expert described a “new era” of the Colorado River in which the future hydrology “cannot be reasonably estimated by simply using the available gauge record.” Basin States “acknowledged the potential for impacts due to climate change and increased hydrologic variability” and collaborated on scenario planning in response. The 2007 Interim Guidelines defined specific deliveries to each Basin at stepped storage elevations of the reservoirs. Cognizant of the highly uncertain water supply in the Basin, the Guidelines defined allocations which addressed surplus, normal, and shortage conditions. The Guidelines included further protection from shortage by giving the Secretary of the Interior the authority to take additional necessary actions at critical elevations to avoid Lower Basin shortage as the conditions approach thresholds.