DOI to Continue High Flow Experiments at Glen Canyon Dam
The Department of the Interior will undertake an experimental initiative to improve the management of Glen Canyon Dam and the Colorado River as it flows through Grand Canyon National Park, Secretary of the Interior Ken Salazar announced recently during the Colorado River Water Users Association conference.
“We must find a way to protect one of the world’s most treasured landscapes – the Grand Canyon – while meeting water and clean energy needs in the face of climate change,” Salazar said in a video message to the water users’ meeting at Caesar’s Palace in Las Vegas. Salazar was participating in the global climate change conference in Copenhagen.
“Today, I am directing the development of a protocol for conducting additional High Flow Experiments at the Dam,” Salazar said. “These experimental high flows [like the one in 2008] send sediment downstream to rebuild sandbars, beaches and backwaters. The rebuilt areas provide key wildlife habitat, enhance the aquatic food base, protect archeological sites, and create additional camping opportunities in the canyon.”
“We’ve put in place a comprehensive science program designed to figure out the complex processes at work downstream of Glen Canyon Dam, so that we can get better at managing the river for the benefit of all the various resources at stake,” Assistant Secretary Anne Castle explained in a follow-up speech to the Las Vegas audience. “We can make [high flow releases of short duration] without affecting the overall amounts of water required to be released from Lake Powell by the 2007 interim guidelines and the Law of the River.”
“We will engage all our partners in this effort – from federal agencies and tribes to local and state governments and other stakeholders,” Salazar said. “We also recognize the need for additional experimental and management actions to protect the resources of Grand Canyon National Park, and these efforts will be implemented through the Glen Canyon Dam Adaptive Management Program.”
Because Glen Canyon Dam traps approximately 90 percent of the sand once available to maintain Grand Canyon sandbars, high flows are a good tool to rebuild these important resources. The new protocol will allow for high flows to occur when Colorado River tributaries below the dam produce sufficient sediment to meet a threshold, or “trigger.” Timing of high flows would depend not only on sediment inputs from tributaries, but also other environmental considerations such as impacts to the Lees Ferry trout fishery and riparian vegetation.
The new protocol also will protect the interests of those relying on the Colorado River, as the water released during the high flow will not change the annual amount of water to be released to downstream users from Glen Canyon Dam. That water flows downriver to Lake Mead for use by the Lower Colorado River Basin States and the Republic of Mexico.
The most recent High Flow Experiment at Glen Canyon Dam was conducted in March 2008. During the experiment, the Bureau of Reclamation released water from both the power plant and the bypass tubes to a maximum amount of approximately 41,000 cubic feet per second for about 60 hours.
Preliminary results of the 2008 experiment show a robust sandbar building response and sandbar development throughout the river corridor. However, considerable erosion occurred following the experiment. Research on the effects of the 2008 event on a range of resources—including native fish, vegetation, the Lees Ferry trout fishery, and more—will be completed by the U.S. Geological Survey in January 2010 and this additional information will be taken into consideration in the development of the new protocol.