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

29

February 2, 2007

Hypotheses to Be Evaluated and Information Needs to Be Filled

· Flow and stage at which floodplains with levee breaches become sufficiently inundated
(U6).

· Frequency of floodplain inundation relative to the hydrologic cycle (A5).

· Persistence of floodplains after peak flows recede (U7).

· Rates of sediment deposition and erosion in breaches and floodplain depressions (U15).

· Entrainment and retention of larvae as a function of physical characteristics of
floodplains (U9).

· Temporal relationships between drifting larvae and hydrology needed to entrain larvae in
floodplains (U1O).

· Area of terrace and depression floodplains at different flows (U5).

· Benefits of lower peak flows for longer duration vs. higher peak flow for a shorter
duration for a given volume (U14).

Implementation

· Ongoing Project Cap 6 rz/entr.-A final report for bead and larvae entrainment studies is
due at the end of 2007 (FY 2008).

· Ongoing Project 851- Sediment monitoringfinal report is due in FY2008.

· New Start.-A synthesis report that summarizes and integrates all physical and biological
floodplain inundation and entrainment studies should be started in FY 2008 and
completed in FY 2009. The results of this synthesis should be used to determine the need
for additional studies.

3: Continue annual monitoring of razorback sucker larvae in the mainstem,
and synthesize existing information on drift and its relationship to flows and
other environmental conditions.

Description

Annual larval monitoring provides useful information relevant to a variety of ongoing
studies and for evaluating the effects of flow recommendations. By determining the presence of
larvae in the system and correlating that with the connection of floodplain nursery habitats to the
mainstem, it may be possible to develop dam operational strategies that optimize larval
entrainment. This evaluation, should, among other things, assess the possibilities for meeting the
goals of the flow recommendations for larval entrainment at various peak flows.