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~ . . . Inputs in the July - October 2002 period the dam is operated at a constant 8,000 cfs following sediment inputs (or perhaps a low level, e.g. 5-9,000 cfs ROD flow) until January 2003. In January 2003 a BHBF ofIimited duration is conducted. This is followed by experimental (non MLFF) Load-Following flows for the duration of the non-native spawning and emergent/juvenile season (perhaps several months). Syring and summer 2003 operations would follow monthly volumes under the ROD. 'J;his hydrograph could be repeated in WY2003-04. f-r>O J-::>;~ or/) The BHBF to be released in January 2003 should have a magnitude of at least 10,000 cfs above peak powerplant discharge, or higher depending on lake elevation. A year with significllnt sediment inputs would be defined as an instantaneous discharge of 2,000 cfs or greater from the Paria River or an instantaneous discharge of 10,000 cfs or greater from the LCR during the period August I-October 31. C). Figure 3. This scenario represeJlts a year when there are no significant monsoonal sediment inputs but there are sediment inflows in winter. It also includes flows intended to benefit native fishes. If there are No Sediment Inputs in the July through October period the dam would be operated under nonnal ROD operations until December 2002. Beginning in January 2003 experimental (non MLFF) Load-Following for duration of non-native spawning and emer ent/'uvenile season erha several months) would unplemented. pring and summer operations would follow monthly volumes bnder-the-ReB;-Bnderihiln:ondition,-a-BHBF-wouid-occurifsignificantsand--- . inputs occurred during the winter/spring runoff period (e.g. LCR in Jan.-Feb. 1993). If sand inputs occur in winter/spring, then a BHBF would be released as soon as possible and in the same month that the sediment input(s) occur. The BHBF would have a magnitude of at least 10,000 cfs above peak: powerplant discharge, or higher depending on lake elevation. Hvdroe:raph see:ment rationale + The reduced-flow period (10.000 cfs or less) in August-December - is intended to provide some benefit to native juvenile fish, and conserve sediment in the main channel when significant tributary sediment supplies are introduced to the ecosystem. The potential advantage to native fish habitat would likely be marginal, and not accrue until year two under these recommendations. HI: Reduced-flows following sediment inputs reduce downstream transport while turbidity levels are elevated, such conditions provide some additional predator avoidance benefit to YOY native fishes. H2: Reduced flows in the August- October period do not decrease juvenile HBC mortality in the main channel of the Colorado River. H3: Reduced flows following sediment input does not conserve fine-sediment in the main channel. Version 1.2 - 2/15/02 4