Laserfiche WebLink
DRAFT DRAFT DRAFT <br />A. Current Management of Downstream Releases from McPhee Reservoir <br />Baseflow Management The current management objectives for release of <br />baseflow from McPhee are to provide enough water during the spring, summer, <br />and early fall months to maintain a healthy trout population below the dam. <br />Winter flow studies in the early 1990s indicated that habitat availability is <br />maintained by flows as low as 30 cfs. Provided that the fishery /baseflow pool is <br />full, flows greater than 30 cfs are preferentially released spring through fall to <br />maintain adequate summer temperatures. Releases of 30 cfs generally persist <br />from November through March. Spring flows ramp slowly April through June, <br />and peak annually in July and August to approximately 60 cfs to minimize <br />thermal stress to Coldwater species. Flow in September through October ramps <br />down to winter baseflow of 30 cfs, generally beginning sometime mid-October or <br />November, depending on water availability. In addition, a 12-hour fish stocking <br />release of 400 cfs (400 AF) is often scheduled annually near October 1, based <br />on fish availability. <br />Spill Management Spill management criteria apply to management of water <br />supplies excess to Project and other water demands in McPhee (the "spill <br />water"). Operations criteria that relate to spill management are presented below. <br />McPhee Operations Criteria (BOR, 2005): <br />• Fill the Reservoir when possible. <br />• Do not allow the reservoir to exceed elevation 6920.00 prior to the end of May <br />(this condition allows for 4 vertical feet of freeboard as flood control in the <br />event of rapid snowmelt after May 31 ). <br />• Manage releases to provide white water boating opportunities, when possible. <br />• Try to peak releases over the Memorial Day weekend. <br />• Manage releases in such as way that it is not necessary to use the <br />emergency spillway (fully utilize the selective level outlet works for ALL <br />managed spills). <br />• Provide a minimum of 2,000 cfs for seven days for channel maintenance. <br />• Try to limit releases to less than 4,000 cfs. <br />• Provide a minimum raftable release of 800 cfs as long as possible. <br />Managed spill releases end when reservoir inflows match the project demand. <br />The resulting hydrology over the last 20 years suggests that when there is a <br />large spill anticipated, there is often one occasion prior to June 1 when a large <br />quantity of water is released rapidly for a short period to ensure the flood <br />capacity restriction is maintained (maximum water surface elevation of 6920 ft <br />before June 1). The target for the maximum release is the Memorial Day <br />weekend. Although there is no provision for ramping flows noted above, when <br />flows are less than 800 cfs, ramping of no more than 200 cfs over a two day <br />period is usually maintained. <br />9/5/06 ~ <br />