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<br />Upper Basin Reservoirs
<br />Fontenelle Reservoir
<br />[Green River]
<br />
<br />N.ltr Vo.r 1883
<br />rhe water year 1983 plan of operation for
<br />:'ontanelle Reaarvolr was formulated In
<br />espof'rseto evidence of Increased seepage
<br />.bserved along the left abutment of the dam
<br />nth. fal' of 1982. Starting In mid-September
<br />IOd continuing through October 1982, the
<br />'W'ster surface elevation was drawn down 11
<br />eet to elevation 6495 feet In order to Initiate
<br />In Intensive drilling and test program to
<br />IW8stlgate the cause and to determine what
<br />emedlal actions were reQuired. During this
<br />Isrlod of rapId drawdown, maximum average
<br />ally releases reached 10,000 cts.
<br />
<br />.0 ensure safe operation of the dam, 8
<br />eclslon was made to restrict the maximum
<br />rater surface elevation In water year 1983 to
<br />,496 toot, 10 fe.t belOW the spillway crest.
<br />hrough the remaInder of winter and spring,
<br />1e water surface waB graduallY lowered to
<br />.Ievatlon 6476 taet by April 20, 1983.
<br />Ithough the April through JulY runoH above
<br />=ontenelle ReservoIr was 1,239,000 acre--feet,
<br />lpproxlmately 142 percent of average, the
<br />eservolr was maintained below water surface
<br />,Ievatlon 6496 teet, except for 3 day. during
<br />he peak Inflow.
<br />
<br />~axlmum water surface elevation of the
<br />!servolr reached 6497 feet wlttl a content 01
<br />74,500 acre-teer on June14, 1983. Peak
<br />,tlow ot 11 ,770 cts oGCurred on June13 1983
<br />urlng this period the maximum averag'e .
<br />illy outflow from the reservoir was 9,130 cfs.
<br />
<br />early July 1983, a decision was made, based
<br />)on preliminary geologic Information, to
<br />lYer the water surface elevation to 6482 feet
<br />order to accelerate the testing program.
<br />Ithln 2 weeks, the water surface was
<br />Nered 'rom elevation 8495 te.t to 6482 teet.
<br />iring this period, ma)(lmum average dally
<br />'Charge reached 12,150 cts, stltll ,000 cts
<br />,8 than the safe channel capacity below the
<br />m. The water surface elevatIon remained at
<br />near elevation 6482 teet throughout the
<br />nalnder of the water year.
<br />
<br />total of 2,029,000 acre-feet was released
<br />ough the reservoir during water year 1983,
<br />hI ,011 ,000 acre-teet bYP88slng the
<br />'ierplant.
<br />
<br />
<br />W.llr V..r 1984
<br />At the beginning ot water y.ar 1984,
<br />Fontenelle Reservoir was at water surface
<br />elevation of 6482 feet, with a water storage
<br />content of 177 ,000 acre-feet. The t.stlng and
<br />monitoring program will continue through
<br />water year 1984. Preliminary results of these
<br />Investigations are expected by January 1984.
<br />Final results with recommendatIons for
<br />necessary remedial action are due by August
<br />1984.
<br />
<br />Due to the extensive monitoring network, the
<br />dam can be operated safely to supply
<br />downstream water needa. However, the
<br />reservoir wIll be operated at reduced levels,
<br />between water surface elevatIons 6475 feet
<br />and 6482 feet. The reseryolr will be gradually
<br />drawn down to elevation 6475 feet prior to the
<br />spring runoff, and will then be allowed to rlae
<br />to elevation 8482 feet during the peak ot the
<br />runoff. The r&servolr will be maintained at or
<br />near this elevatIon through the remainder of
<br />the water year.
<br />
<br />The maxImum release from the reservo\r wIH
<br />be primarily dependent on the magnltuda ot
<br />the runoff. It the runo" la In the upper decile,
<br />the peak outflow Is expected to be
<br />approximately 9,000 ct.. An upper quartile
<br />runoff would result In a peak outflow of
<br />approximately 7 ,500 cfs. With an average
<br />runott, the anticIpated peak outflow Is 8,000
<br />cfs. Assuming a lower quartile runoff, or less,
<br />the outflow will probably be no greater than
<br />4,500 cf..
<br />
<br />Fontenelle I Active Storage.
<br />
<br />Reservoir (Acre-Feef)
<br />
<br />Maximum Storage 344,834
<br />Rated Head 233789
<br />Minimum Power 194:962
<br />Surface Area (Full) 8058 Acres
<br />Reservoir Length
<br />(Full) 18 Miles
<br />
<br />Power Plant
<br />Number at Units
<br />Total Capacity
<br />
<br />Chart 1
<br />EI.(Fl.)
<br />6506
<br />6491
<br />6485
<br />
<br />1
<br />10,000 Kilowatts
<br />
<br />.~~awng~&1~U::e 563 acre-reel 01 dead storage
<br />
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