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<br />Proposed Fall 1997 Release from Glen C.ulVon Dam <br /> <br />October 6. 1997 <br /> <br />f <br />; <br />; <br />\ <br />r <br />" <br /> <br />,i <br /> <br />inflows, but it will take the available Paria sediment with it. Fashioning a :-day release at ~. <br />powerplant capacity is expected to save the sediment and accomplish the required water release at <br />the same time, The only other option is to choose not to do the test, bypass the opportunity, and <br />lose the sediment downstream. <br /> <br />Q: How did Reclamation determine there's extra water available to push this sediment with? <br /> <br />A: The following is from the Draft 1998 AOP: "During water year 1998. releases greater than the <br />minimum release objective of8,23 maflikely will be made to avoid anticipated spills and/or to <br />equalize the storage between Lakes Powell and Mead. Und'er the most probably inflow <br />conditions, releases of 10,95 mafwould be made... The maximum probable inflow '5 3 maf) <br />would require releases of about 25,000 cfs for a lengthy period of time." <br /> <br />Q: What if we fail to take action? <br /> <br />A: Mark Anderson of the USGS explained that the data shows that the sediment from the Paria <br />will be pushed out of the area should the maintenance flow not be done. This would result in a <br />lost opportunity to deposit the sediment and keep it nearer where it will be needed in the future. <br />Timing the release to occur as planned is important to avoid loss of the accumulated sedin1ent <br />from the Paria to downstream reaches of the river channel, beyond the beaches that are intended <br />to be influenced. <br /> <br />Q: Isn't this type of habitat maintenance flow or beachlhabitat building flow already addressed in <br />the GCD EIS and Record of Decision? <br /> <br />A: Not exactly, The proposed flow does not precisely fit the definition for either of tpose flows, <br />but it contains elements of both. Habitat maintenance flows are defined in the operating criteria <br />for GCD as "steady releases within powerplant capacity not to exceed 14 days in Marcn, although <br />other months will be considered under the Adaptive Management Program, These flows will not <br />be scheduled when projected storage in Lake Powell on January I is greater than 19;000,000 <br />acre-feet." Because the storage in Lake Powell on January I, 1997 was over 19 maf, habitat <br />maintenance flows cannot be scheduled during the 1997 water year. BeachIBabitat Building <br />Flows are defined in the operating criteria as "controlled floods to occur as steady flows not to <br />exceed 45,000 cfs, duration not to exceed 14 days...utilizing reservoir releases in excess of <br />powerplant capacity required for dam safety purposes." Because the proposed flows are <br />projected to be at powerplant capacity, they are not appropriately defined as beach/habitat <br />building flows and that is not the intent anyway. <br /> <br />Q: What does the GCD EIS say about these types of flows? <br /> <br />A: The EIS Record of Decision placed a cap of25,000 cfs on releases from GCD, with <br />authorized exceptions allowed to accomodate emergencies, habitat maintenance flows, <br /> <br />2 <br /> <br />p. <br /> <br />" <br /> <br />:.: <br />i~ <br />'~ <br />~; <br />" <br /> <br />,,' <br /> <br />:... <br /> <br />i.... <br /> <br />. i". <br /> <br />,. <br />!):. <br />k- <br />1.)': <br />:~": <br />;!.~. <br />. , <br />(<.. <br /> <br />,.. <br />~ <br />'~., <br />l".: <br />~~ <br />r~~ <br />~ <br />''< <br />~:~ <br />