Tuolumne River Report - U.S. Fish and Wildlife Service

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CHAPTER 3108Table 3-8. Wy 1970-1997 instream releases, and potential modifications to peak flows to improve geomorphic processes.Rank ofMaximum Number of Number of Instream instream Recommended Duration Additional waterdaily average days flows days flows release release additional of peak volume bypassingWater Year discharge (cfs) >3,000 cfs >5,500 cfs (Acre-ft) volume peak flow (cfs) flow (days) power plant (Acre-ft)*1970 7,000 20 13 729,000 9 8,000 3 22,0001971 2,490 0 0 346,000 01972 1,450 0 0 164,000 01973 1,370 0 0 165,000 01974 1,940 0 0 376,000 01975 3,080 2 0 561,000 01976 2,730 0 0 360,000 01977 224 0 0 67,000 01978 4,570 10 0 292,000 5,500 3 01979 3,650 36 0 657,000 10 5,500 3 01980 7,280 76 38 1,493,000 5 10,000 2 44,0001981 2,980 0 0 441,000 01982 8,150 113 49 1,718,000 4 10,000 2 44,0001983 10,400 288 118 3,465,000 1 12,000 1 69,0001984 8,010 130 14 1,376,000 6 10,000 2 44,0001985 2,820 0 0 376,000 01986 6,870 68 37 1,134,000 8 10,000 2 44,0001987 2,980 0 0 283,000 01988 588 0 0 78,000 01989 767 0 0 61,000 01990 861 0 0 85,000 01991 1,190 0 0 83,000 01992 1,150 0 0 81,000 01993 1,760 0 0 241,000 01994 3,080 1 0 187,000 01995 8,710 151 89 2,185,000 2 12,000 1 69,0001996 6,790 77 9 1,183,000 7 8,000 3 22,0001997 55,865 96 74 1,959,000 3 12,000 1 69,000TUOLUMNE RIVER TECHNICAL ADVISORY COMMITTEEHABITAT RESTORATION PLAN FOR THE LOWER TUOLUMNE RIVER CORRIDOR*assumes flows exceeding 5,500 cfs bypass power house, ascending hydrograph limb is 2,000 cfs/day, and receding hydrograph limb is 1,000 cfs/day.Also assumes that canals are not in operation at the time of release, so that streamflows equal New Don Pedro Dam release.
GEOMORPHIC AND RIPARIAN INVESTIGATIONS• If possible, extend the duration of flows in the5,500 cfs range for several days after the peakflow event to transport fine sediment downstreamand deposit onto contemporary floodplains(designed to inundate at 4,000 cfs to5,000 cfs).• Larger releases (e.g., 12,000 cfs) should be ofprogressively shorter duration due minimizecoarse sediment transport capacity and attenuatehigh flow peak magnitudes in downstreamurban areas. Initial suggestions for high flowduration for 8,000 cfs, 10,000 cfs, and 12,000cfs fluvial geomorphic releases are 3-day, 2-day,and 1-day duration respectively to minimizedownstream gravel flux while exceeding bedmobility thresholds (Figures 3-22 to 3-29).• Down-ramping rates should be at, or lower than,rates specified in the FSA and ACOE floodcontrol manual to minimize juvenile chinooksalmon stranding.• Years in which flood management releases arenecessary tend to come in multi-year sequences;therefore, in the first wet year after severalsequential dryer years, a larger flow should bereleased if feasible (e.g., 12,000 cfs) to reverseriparian seedling initiation on active channelalluvial deposits, reducing riparian encroachmentrisk.• The magnitude and duration of these flowsshould be re-evaluated continuously as part ofthe adaptive management program to evaluatewhether bed mobility, bedload transport, sandtransport, channel migration, and bed scourobjectives are being met.• Extremely wet years with extensive floodcontrol releases in the spring should target verygradual ramping rates to encourage riparianregeneration on contemporary floodplains.Ramping rates targeting natural Fremontcottonwood regeneration should be less than 3cm/day to allow their taproots to follow thedescending moist capillary fringe.These recommendations were developed to avoidinterference with water allocations contained inthe FERC Settlement Agreement, and to minimizeloss of power generation revenues whenbypass flows would normally occur. We suggestthat geomorphic and biological monitoringexperiments be developed and implemented (e.g.,impacts of flow magnitude and duration to reddscour and egg mortality) prior to each winterseason, in the event flood management releasesoccur. We recommend that the TRTAC closelymonitor whether flood flows are achieving fluvialgeomorphic and biological restoration objectives.The most significant potential shortcoming of theabove approach is long sequences of dryer years(1971-1977, 1987-1994) that allow riparianvegetation to initiate and establish on newlyrehabilitated reaches and newly deposited alluvialsurfaces.3.2.3. Constraints (sediment supply,floodway width, structuralencroachment)One result of the January 3, 1997 flood peak wasthe immediate perception that we needed to dosomething to prevent this from happening again.Some commonly suggested immediate solutionshave been more storage (more or bigger dams),levees, or purchasing more flood control space inexisting reservoirs. Out of this reactionary noiseemerged a solution that could benefit a variety ofneeds: increased floodway capacity to improveflood management and flood control flexibility.There are several primary considerations whenconsidering flood management solutions: maintainagricultural and municipal water supplies,providing flood control, protecting private andpublic property, ensuring human safety, positiveand negative impacts to the environment, andcost. Purchasing flood control space in NDPPprovides additional flood control protection, butreduces water supply, imposes a large cost to thepublic, and reduces environmental benefitsprovided by higher flood control releases.Constructing levees can contain floods, but theyoften provide a false-protection by allowingdevelopment behind them, and when they fail,flood damage increases. Additionally, the cost oflevee construction and maintenance is large andgreatly reduces the environmental quality of theriver corridor.A logical, long-term solution is to restore acontinuous floodway and meander corridor fromLa Grange downstream to the San Joaquin Riverthat provides flood conveyance up to 15,000 cfsupstream of Dry Creek and 20,000 cfs to the SanJoaquin River. This strategy is integral to restoringfluvial geomorphic processes to the TuolumneRiver, while at the same time reducing the risk ofcatastrophic floods (e.g., 1997 flood), greatlyimproves salmon habitat, provides property andhuman protection, preserves agricultural andmunicipal water supplies, and provides operatorsCHAPTER 3109
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Habitat Restoration Plan for theLow
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TUOLUMNE RIVER TECHNICAL ADVISORY C
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CHAPTER 226Table 2-5. Revised minim
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CHAPTER 2TUOLUMNE RIVER TECHNICAL A
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CHAPTER 2TUOLUMNE RIVER TECHNICAL A
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ADAPTIVE MANAGEMENT5. ADAPTIVE MANA
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ADAPTIVE MANAGEMENTmonitoring progr
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ADAPTIVE MANAGEMENTWILDLIFE POPULAT
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ADAPTIVE MANAGEMENT• Distribution
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REFERENCESREFERENCESAlderdice, D. F
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REFERENCESKjelson, M. A., P. F. Raq
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REFERENCESTID (Turlock Irrigation D
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APPENDIX AAPPENDIX AANNUAL HYDROGRA
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APPENDIX BAPPENDIX BTUOLUMNE RIVER
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VEGETATION SERIESNATURAL DIVERSITY
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VEGETATION SERIESNATURAL DIVERSITY
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Nature Conservancy Heritage Program
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215Scientific Name Common Name Loca
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APPENDIX BAPPENDIX B217
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Tuolumne River Report - U.S. Fish and Wildlife Service

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