Glen Canyon Dam Power Generation

The EDF "Study" - Power Issues


The book "Glen Canyon", by Steven Hannon (Kokopelli Books 1997) has a cast of characters who set out to irreparably damage Glen Canyon dam by using a nuclear warhead. Mr. Hannon wasn't the first to come up with this idea. The Soviet Union's list of ICBM targets, which was made public several years ago, had the Page, Arizona area listed. So there have been (and probably still are) nuclear warheads with the coordinates of Page programmed into their guidance systems.

The strategic importance of having a "hydro" power plant tied to a large coal fired plant was not lost on our former Cold War enemies.

Between Glen Canyon dam and the Navajo Generating Station there is over 3,000 MW of generation available. The importance of this situation has been proven during several large scale outages in the Western U.S. during the last two decades. Glen Canyon dam has played a key role in getting the "Western Grid" back on line during each of these outages.


The maximum generation of Glen Canyon Dam is 1,356 MW. The Bureau of Reclamation controls the flow of water through the dam, and therefore the electrical output of the generators. Under the Grand Canyon Protection Act of 1992, an Environmental Impact Statement process was conducted that had participation of all interested parties--water, power, environmental, game and fish, Native American, etc. Under the Final Record of Decision of the EIS, a federal advisory committee was established - the Glen Canyon Adaptive Management Work Group. The Work Group makes recommendations to the Bureau on flows. It is this Work Group that sets the dispatch rules for Glen Canyon, following the requirements set out in the EIS Record of Decision.  Those requirements address the following range of needs:  water (irrigation & Central Arizona Project), power, beach building, critical wildlife habitat, endangered species, fish and game, Native American cultural sites, etc.  The dispatch rules do allow for Glen Canyon generation to respond somewhat to varying power needs, but the response is limited within a generation bandwidth specified by the Work Group.  The Work Group sets maximum ramp rates within an hour and over certain number of hours.Under current regulation the dam now generates between 500 and 900 MW on average during a year (depending on the snowpack upstream).


Glen Canyon Dam flows are dispatched based on electrical needs in Phoenix.

Glen Canyon Dam is the major generator for the Colorado River Storage Project (CRSP). Depending on the runoff during the year Glen Canyon provides 75-85% of the total CRSP generation.

CRSP power contracts are primarily with Rural Electric Co-ops, small municipalities, Native American reservations, and government facilities. The total number of customers is 174. Typical customers are; Raton, New Mexico; Beaver, Utah; Center, Colorado; the Navajo Tribal Utility Authority; and Ely, Nevada. Prior to the Rural Electrification Administration these customers did not have reliable electrical service. Investor owned electric utilities did not have any incentive to provide these customers service since the cost of the transmission and distribution lines required was significant and the potential for their usual profits was not there. Most of the CRSP customers are small rural entities with low per capita income levels. The WAPA power is less expensive than typical investor owned utility costs, but the pricing is based on covering operation and maintenance costs for the generation and transmission facilities, providing capital for irrigation projects in the West, and also paying back the U.S. Treasury for the cost of facilities' construction. This type of pricing is also the norm for areas serviced by the Tennessee Valley Authority (TVA), and the Bonneville Power Administration (BPA) among other REA customers.

Power does go to Phoenix through an agreement with the Salt River Project (SRP) which also operates the Navajo Generating Station. SRP owns significant portions of two coal fired plants in Colorado (Craig and Hayden). SRP dispatches (orders electrical output changes to) the coal plants, and then the power is traded with the Western Area Power Administration (WAPA) which supplies power from Glen Canyon to SRP. This agreement was made to save the millions of dollars it would have taken for both power suppliers to build new transmission lines. The coal fired unit's power goes to the WAPA customers in Colorado and Utah. The WAPA customers pay based on the WAPA rates, and the SRP customers pay based on the coal fired plants rates. As noted above, the flow fluctuations are based on the CRSP load, not the Phoenix electrical loads, and these fluctuations are limited by the requirements set out in the EIS Record of Decision.

Summary of CRSP customers Rocky Mountain customers Southwest customers CSC Customers


There is a huge surplus of generation in the Southwest.

While during much of the year there is more than enough generation in the Southwest to take care of customer loads, when it gets to July and August this surplus disappears. The North American Electrical Reliability Council has projected an August 1998 margin (available generation over peak customer load) for Arizona, New Mexico, and Southern Nevada of 14.3%. They begin to get concerned about system reliability when the margin is below 12%. The national average margin for August is 18.1%. Even when the "Rocky Mountain" area (Colorado, Utah, Idaho, and Montana - more area than the EDF study addresses) is included the margin is still only 16.5% (still below the national average). Glen Canyon Dam's available generation capability of 1,356 MW represents 25% of the margin for the total area. Without Glen Canyon Dam's generation the margin drops to 12%, or the point where system reliability is questionable. See note at the bottom of the page. As of July 1, 1998 this assumption became comical.

This leads us to:


In a report prepared by Spreck Rosenkrans of the Environmental Defense Fund (EDF) it is stated that "The total loss of hydropower generation as a result of draining Lake Powell is projected to be 4551 GWh/year, about 3% of the 166,249 GWh generated in the four state area (Colorado, Utah, Arizona, and New Mexico) where most of Glen Canyon Dam's power is consumed."

This statistic has shown up in newspaper articles, and Daniel Beard's speeches and press releases. While Mr. Rosekrans is considered an expert in river hydrology by both sides of this debate concerning draining Lake Powell, he has used this statistic for electrical generation that has little pertinence to the debate.

First, over 20% of the generation in the four states mentioned is owned by utilities in Southern California and Texas, not to mention the excess energy sales that are made by utilities in these four states to the "Black Hole" of electrical consumption that is Southern California. So the 3% number itself is incorrect. But as stated above average power consumption means little compared to peak power requirements, making average generation statistics irrelevant to the importance of a generating facility.

There are two pertinent statistics - the first as noted above - During peak load conditions, Glen Canyon Dam capability represents 25% of the capacity margin for the Rocky Mountain States, and the South West (excluding California). Without Glen Canyon dam the margin would drop to 12%, or the level where system reliability is in question. This is compounded by the fact that a large portion of the margin is produced by large coal fired units which have inherent reliability problems compared to hyro power generating units.

The second pertinent statistic was provided by the Colorado River Storage Project Customer Service Center - Glen Canyon Dam provides approximately 20% of the power used by the CRSP customers.

This means that to meet peak loads during the summer months additional generating capacity would have to be built. The new capacity would probably be Natural Gas fired generation (with the accompanying increase in CO2 into the atmosphere). During off peak times the power would be made up using the next lowest cost generation sources compared to hydro power - coal fired plants.

The report also fails to recognize the strategic importance of hydro-generation units in getting the "grid" back in service. A hydro unit can provide power in a matter of minutes, where a large coal fired unit can take hours or days to get back to full load and requires a significant amount of power from an off site source (preferably a hydro power generator).


We have a new record! "Generation Critical Status" for this year began on June 25, 1999!

As of last year the following was the case.....

The Navajo Generating Station as well as the majority of the significant generating units in the Southwest were put on "Generation Critical Status" on July 1, 1998. This is the earliest this has occurred. On October 13, 1998 a"Generation Critical Status" was also declared. This is latest that this has occurred. The following is the message sent to the SRP generating units when this occurs:

This term indicates a condition where SRP currently has adequate capacity to
meet customer demand and operating reserve requirements. However, if a major
generating resource were lost, SRP might not be able to find sufficient capacity to replace it.

When a "CAPACITY CRITICAL" condition is in effect, all generating stations should:

1. Stop any maintenance that could jeopardize the availability of any on line
or standby unit.
2. Review procedures to reduce non-critical auxiliary load.

So much for the "surplus of power" that the EDF study and and other sources have made available to the media!


Last Years event (this year will probably be worse).

Proof of the lack of "surplus power" (Summer 1998 outages in the States which receive Glen Canyon Dam Power):

July 17, 1998 - Denver experiences "rolling blackouts"

Return to Home Page