The Department of Interior last week announced plans to release an
experimental high flow from behind Glen Canyon Dam to help recover
endangered fish and other resources downstream in Grand Canyon National
Park.
Federal officials hope the surge, which will mimic historic, pre-dam
flows on the Colorado River, will deliver sediment downstream and
rebuild eroded beaches. Beaches and sandbars provide crucial habitat
for wildlife and create backwaters for native fish, including the
endangered humpback chub. The accumulation of sand also helps protect
archaeological sites.
The Bureau of Reclamation, which manages the dam, conducted a similar experiment in 2004 (Land Letter,
Dec. 2, 2004). The new experiment, announced Jan. 17, will build on the
information gleaned from the 2004 experiment and another in 1996, said
John Hamill, head of the U.S. Geological Survey's Grand Canyon
Monitoring and Research Center. This time, there is an influx of sand
in the Colorado River system, which will be carried by the high flows
released from the dam.
"Given the current amount of sand
in the system, we have a tremendous opportunity to learn more about
whether high flows can be used to improve important natural, cultural,
and recreational resources in Glen and Grand canyons," Hamill said.
If
the secretary of the Interior Department approves the plan, Reclamation
will send 41,000 cubic feet per second of water surging down the
Colorado River through the Grand Canyon for about two-and-a-half days.
That is more than twice the amount of water typically released from the
dam; since 1996, releases have ranged between 8,000 and 20,000 cubic
feet per second.
The effects of the high flows,
tentatively scheduled to begin March 4, will be studied by a cadre of
federal scientists. The experiment will "provide the valuable
information needed to protect the resources within Grand Canyon
National Park," said Steve Martin, superintendent of Grand Canyon
National Park.
Under the Grand Canyon Protection Act,
Reclamation must make sure operations are conducted in a way that
protects Grand Canyon resources.
Larry Walkoviak of
Reclamation said the experiment will not increase the overall amount of
water released over the course of the 2008 water year. Monthly releases
later in the year will be lower to make up for the higher flows in
March, he said.
Criticisms
But critics say the experiment is not enough to help the park's resources, which have suffered because of the dam.
"This is a half measure," said John Weisheit, conservation director
for Living Rivers. "Unless they do it every year, it's not going to
work."
And the amount of sediment flowing in from the
Paria River and other tributaries is insufficient to make up for the
dam's restriction of sediment in the Colorado River itself, he added.
Dam managers estimate that 92 percent of the sediment that would be
carried downstream by an undammed river is blocked by Glen Canyon Dam.
"They
seriously need to start looking at other alternatives, which are
sediment augmentation and decommissioning," Weisheit said.
Augmentation
would involve trucking or piping sediment around the dam, an option
that has been discussed but never tried, partly due to its exorbitant
expense. Decommissioning would involve breaching or removing the dam, a
controversial option Living Rivers has advocated for years but
Reclamation and power interests oppose.
In December, environmental groups filed suit against Reclamation over the agency's normal operation of the dam (Land Letter,
Dec. 13). The groups argue that a 1994 biological opinion from the U.S
Fish and Wildlife Service requires the agency to release high flows in
the spring and low flows in the summer and fall to benefit the chub.
Currently, Reclamation releases low, fluctuating flows throughout the
year.
A final decision on the experimental flow proposal is expected in late February.
April Reese writes from Santa Fe, N.M.
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