WSP03947

• File Number: 8220.101.09
• Description: Glen Canyon Dam/Lake Powell
• State: AZ
• Basin: Colorado Mainstem
• Date: 2/25/1999
• Author: USDOI-BOR
• Title: Implementation of Glen Canyon Dam Operations Biological Opinion-1998 Progress Review
• Water Supply Pro - Doc Type: Biological Opinion

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ELEMENT 1.A
Carry out a program of experimental flows, including high steady flows in the spring and low
steady flows in summer and fall during low water years, The RPA set forth a schedule for
development and implementation of low flows, Design of experimental flows and associated
studies were to be completed by October 1996, Unless the Service doubted the validity of the
study design or the ability of the flow to contribute to removal of jeopardy, the flows were to be
implemented in April 1997. The flows could begin even later in 1997, if good faith effort to make
sufficient progress were demonstrated, Absent sufficient progress, flows were to be
implemented in the spring of 1998.

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PROGRESS ELEMENT 1.A.
Although a release combining both high steady spring flows and low steady summer and fall
flows has not been realized, test of a high spring flow was completad in March, 1996. Research
during the 1996 experimental beach/habitat-building flow (BHBF) concluded that the 45,000 cfs
stage had the effect of filling in some retum channels, thus reducing backwater numbers.
Backwater numbers have also decreased since April 1996 due to deposition of sediment into the
retum channel and erosion of higher elevation reattachment bars.

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Timing, duration and magnitude of BHBFs, and effects on endangered species, are still subject
to speculation and require further testing and validation, In addition to achieving anticipated
benefits to humpback chub habitat, higher stage experimental BHBFs have been recommended
to test the precision of estimated stage-to-discharge relationships at terrestrial endangered
species sites, including Kanab ambersnail habitat at Vaseys Paradise, and the four historic
southwestem willow flycatcher nesting sites,

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A low flow study design has not been done, and the low flows have not been implemented, Low
steady flows were not implemented in 1998, as called for in the opinion, because the forecast
did not predict an 8,23 maf water year. The opinion recognizes that during moderate and high
release years, Reclamation shall operate Glen Canyon Dam according to requirements of the
Modified Low Fluctuating Flow (preferred) altemative, Progress is being made for planning for a
low flow, so that when an 8.23 maf release is projected, Reclamation can be prepared to
coordina1e with the other participants in the AMP and implement the test flow,

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Reclamation accepted the Service's recommended RPA in an April 6, 1995 response to the BO,
This letter of response indicated how Reclamation would implement the RPA. In this response,
Reclamation articulated that:

1) implementation of experimental flow are to be coordinated through the AMP;

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2) the flow experiments will include scientifically based peer reviewed criteria to measure
and evaluate their impacts on downstream resources; the research would be managed
and administered through the GCMRC; and that appropriate staff and funding levels
needed to be identified. This memorandum was distributed to all cooperating agencies
and interested parties.

In 1997, Reclamation contracted with SWCA, Inc, Environmental Consultants, to summarize and
evaluate known information about native and non-native fishes in Glen and Grand Canyons, The

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