Feds hope to improve environment in the Grand Canyon
By Summit Voice
SUMMIT COUNTY — Lake Powell, the key reservoir in the Colorado River system, ended the 2012 water year at just 57.5 percent of full and will continue to drop through the fall, with a steady release of about 8,000 cubic feet per second scheduled through October.
Despite the low-water year, the Bureau of Reclamation is considering implementing a high-flow regime in November, as part of an effort to mimic natural flood conditions on the great River considered essential for maintaining wildlife habitat and potentially reducing erosion of archaeological sites.
The high flows may also enhance riparian vegetation, maintain or increase camping opportunities, and improve the wilderness experience along the Colorado River in Grand Canyon National Park. The protocol is designed to take full advantage of sediment provided by tributaries of the Colorado River as a result of rainstorms and monsoons.
According to BuRec, preliminary sediment estimates appear favorable for a high flow experimental release to occur during the period of November 18 – 25, 2012 should sediment and other conditions warrant.
The total water release for the year from Lake Powell was about 9.46 million acre feet. The inflow during the peak April through July runoff season was just 2.06 million acre feet, which is 29 percent of average and the third-lowest April-to-July period on record, behind 1977 and 2002.
Lake Powell reached its peak for water year 2012 on June 3rd at 3636.90 feet (63.1 feet from full pool) and 15.640 maf (64.30 percent of capacity), respectively. The peak elevation in 2012 is 24 feet below the 2011 peak elevation of 3660.90 feet.
Interior Secretary Ken Salazar announced experimental high-flow regime last May as part of the Interior Department’s Glen Canyon Dam Adaptive Management Program, touted as “the most important experimental modification of operations of Arizona’s Glen Canyon Dam in over sixteen years.”
“We’ve gained tremendous knowledge about the unique resources of the Grand Canyon in the Colorado River downstream of Glen Canyon Dam over the past sixteen years,” Salazar said last May.
The first program establishes a long-term protocol for testing high-flow releases from Glen Canyon dam to determine whether multiple high flow events can be used to rebuild and conserve sandbars, beaches, and associated backwater habitats that have been destroyed or lost over the years of the dam’s construction and operation.
The high-flow releases build on previous experimental flow operations in 1996, 2004, and 2008 that helped resource managers create a flexible framework for experimental releases through 2020 to determine the optimal timing, duration, frequency of releases to maximize ecological and riparian benefits downstream in the Grand Canyon. For more information on the program, click here.
A second element of the program to improve the aquatic environment of the Colorado River below Glen Canyon Dam involves controlling non-native fish and protecting endangered native fish.
Conservation of native fish, particularly the endangered humpback chub, will be enhanced by reducing the threat of predation and competition from non-native fish and improving critical habitat, based on a final ruling issued by the U.S. Fish and Wildlife Service in 2011.
“Implementation of these two programs marks a huge step forward in integrating the management of a dam that’s critical to the delivery of water and power to millions of people in the Southwest with better conservation of the incredible values of the Grand Canyon,” Assistant Secretary for Water and Science Anne Castle said last spring. “We are refining our operations to reflect what we’ve learned and address the concerns expressed by several Native American tribes about the management of fish at locations honored as sacred sites by many of the tribes and pueblos.”
“The National Park Service is a strong supporter of high flow tests to help determine how best to rebuild and sustain the beaches and sand bars below Glen Canyon Dam. We appreciate the extensive collaboration required to develop these research programs which are critical to preserving the awesome resources and visitor experience along the Colorado River in Grand Canyon National Park,” said Jonathan B. Jarvis, Director of the National Park Service.
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