Glen Canyon Dam Adaptive Management Program WY 2000 Low Steady Summer Flow Randy Peterson, BOR Barry D. Gold, GCMRC A Test of Concept

1995 Biological Opinion Program of experimental flows (high steady spring and low steady rest of year) during low water years Evaluate feasibility of temperature modification of dam releases Help develop Little Colorado River management plan Sponsor rackorback sucker workshop Establish second spawning aggregation of humpback chub downstream of Glen Canyon Dam

Test of experimental flow RPA contained in 1995 Biological Opinion (what, where, when and how to measure). Simulate the aspects of the seasonal pattern of the natural hydrograph to benefit native fish. Provide stable low-velocity near shore habitat and increased water temperature. Included monitoring of sediment storage & transport budget. Purposes of LSSF

LSSF Hydrograph

Grand Canyon Monitoring and Research Center Science Integration Meeting To Discuss the Test of Low Summer Steady Flows April 11, 2000

Planning and Implementation Request by USBR in February 2000 for LSSF study plan. Study Planning - Development of hypotheses, proposed plan and budget Feb. - May Implementation of studies begun in mid-March 2000, some field work continuing through Majority of reports on LSSF due by 12/31/00. Contracting process ongoing. Reiterates need for “lead time” to plan subsequent tests. Trip permitting process greatly accelerated by NPS.

Grand Canyon Monitoring and Research Center Steady flows (i.e., 8,000 cfs) will provide consistently available low-velocity near shoreline habitats. Water temperature will increase during summer steady flows both longitudinally and in and along near shoreline habitats, and 8,000 cfs flow provide greater warming than higher discharges. Productivity (primary and secondary) is enhanced by steady flows and food availability is sufficient to compensate for the increased energetic demands of younger faster growing fish. Assumptions Underlying Endangered Fish Research Flows

Grand Canyon Monitoring and Research Center Steady flows stabilize habitats used and will benefit young fish survivorship. Hydrology that simulates the seasonal patterns of the natural hydrograph benefits native fish more than non-native fish. Predator-prey and competitive interactions between non- native and native fish will not offset the positive effects on native fish derived from the increased availability of suitable habitat for rearing. Assumptions Underlying Endangered Fish Research Flows (continued)

Grand Canyon Monitoring and Research Center Impounding tributary mouths, primarily the LCR, retains larvae and immediate post-larvae allowing them sufficient growth to survive when they enter the mainstem in the summer and find increased suitable habitat. A spike flow of 31,000 cfs for 4 days in spring will create suitable habitat and displace non-native fish, and a spike flow of 31,000 cfs for 4 days in fall will disadvantage non-native fish relative to native fish. Assumptions Underlying Endangered Fish Research Flows (continued)

Grand Canyon Monitoring and Research Center The science plan for WY 2000 low summer steady flows was primarily designed to provide data concerning system-wide or local patterns and responses of resources to low steady flows. The Executive summary for the science plan is in your Program. Four areas of emphasis were included in this plan: physical variables, biotic habitat, primary productivity, and fish response. Two additional areas of study were proposed: effects on Lake Powell water quality, and sediment storage and sediment budgeting. Goals of Low Summer Steady Flow Science Plan

Grand Canyon Monitoring and Research Center The science plan Executive Summary has the almost two dozen Hypotheses that we planned to test through the Low Steady Summer Flow experiment. Now it is time to turn the program over to the scientists and to listen and learn how our understanding of the Colorado River ecosystem has changed through these activities. I expect their to be a rich exchange of ideas over the next day and a half. The challenge will be to synthesize and integrate this new knowledge and use it in an adaptive management context. Hypotheses to be Tested

“We few, we brave few, into the breach …” THANKS to everyone for their efforts to plan and implement this experiment and now to report on their results!!!