In an attempt to finally honor the 1994 recommendations of the Fish and Wildlife Service concerning the endangered native fish in Grand Canyon, the Bureau of Reclamation (BuRec) is considering constructing a mechanism to increase the water temperature released from Glen Canyon Dam.
The purpose of this modification is to warm the water sufficiently to stimulate the reproduction processes of these desert fish in Grand Canyon National Park. The proposed temperature control device (TCD) would provide a mechanism to draw water from near the surface of the reservoir where the water is consequently warmer. When the TCD was first proposed in 1999, concerns were raised by the scientific community about how non-native fish (for example, striped bass) from Lake Mead or Lake Powell reservoirs could affect newly hatched endangered fish.
Another concern is that the warmer water will alter the food base. Glen Canyon Dam has changed the river's natural warm-water food base into an exotic, cold-water food base. It will take time for the ecosystem to respond to the warmer water, which could cause subsequent food shortages for the endangered fish.
There are a total of eight vertical intake tubes that feed water to the generators at Glen Canyon Dam. It has been proposed that five of the eight tubes be retrofitted to include a total of three intakes on each tube, the main intake 230 feet down, another near the top of the reservoir, and the third in between. The total cost is estimated at 60 million dollars. Environmental review is moving forward with a final decision to be made around October of 2003. "We are confident that this experiment will work and I support this endeavor wholeheartedly," says Wayne Cook, executive director of the Upper Colorado River Commission. "The only way we will know that success can be achieved is to build the infrastructure and to see how the ecosystem responds. If it works, then the money was well spent." Concerned citizens who have been monitoring the efforts to save Grand Canyon's endangered fish are not convinced that such an adaptive mitigation plan will work satisfactorily. Says David Haskell, former science director of Grand Canyon National Park, "The water temperature leaving the dam is 30 degrees below optimal for successful reproduction of endangered humpback chub. It is highly unlikely that the TCD, as envisioned by BuRec, will be able to raise the water temperature enough to benefit the survival of the chub. The time needed to design, build and test this device will take several years–years the humpback chub may not have."
