9705

• UCREFRP Catalog Number: 9705
• Author: Green River Study Plan ad hoc Committee.
• Title: Study plan for the implementation and evaluation of flow and temperature recommendations for endangered fishes in the Green River downstream of Flaming Gorge Dam.
• USFW Year: 2007.
• USFW - Doc Type: Upper Colorado River Endangered Fish Recovery Program
• Copyright Material: NO

GREEN RIVER STUDY PLAN

9

February 2, 2007

1. Hydrology.- There were many uncertainties associated with the Flaming Gorge Dam
Hydrology Model that were dealt with through modeling assumptions detailed in the
FEIS.

2. Operational limitations for temperature of water released from the dam.-Reservoir
modeling showed that desired reservoir water temperatures for endangered fish are
available for release, when needed, through the Flaming Gorge Dam selective withdrawal
structure. However, release water is used to cool turbine bearings, and temperature
limitations associated with the bearings may, at times, limit the ability to release warmer
water.

3. Uncertainties associated with increased spillway use.-Increased spillway use from
releases to meet some flow and temperature recommendations may degrade the concrete
in the spillway and cause structural damage. Use of the spillway may need to be limited,
based on observed degradation of the concrete.

4. Fish response to flow and temperature recommendations.-As acknowledged in the flow
and temperature recommendations, response by native and nonnative fishes to
implementation of these recommendations is not known with certainty. Monitoring and
research will be necessary to evaluate fish response for specific life history aspects (e.g.,
reproduction, survival of young, recruitment to adults, etc.) and for population self-
sustainability. Because the endangered fish are long-lived species, it may require several
years to determine successful recruitment to the adult population.

5. Uncertainties associated with floodplain inundation.- The relationship of flow
magnitude/duration and area of floodplain inundation is not known with certainty. To
increase effectiveness of resolving these uncertainties, controlled experiments and
associated studies could be performed that capitalize on hydrologic conditions in a given
year and that address as many uncertainties as practicable in anyone year.

6. RiparianlVegetation.-Response by invasive riparian species, particularly plants, into the
floodplain is not known with certainty if the flow and temperature recommendations are
implemented.

. The ROD identified environmental commitments to clarify Reclamation's intentions in
establishing the process for implementing the flow and temperature recommendations. The
second and ninth environmental commitments of the ROD apply to the development of this
Study Plan.

· Environmental Commitment 2.-"The adaptive management process will rely on
ongoing or added Recovery Program activities for monitoring and studies to test the
outcomes of modifying the flows and release temperatures from Flaming Gorge Dam,
and will rely on the Flaming Gorge Working Group meetings for exchange of
information with the public. "