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<br />" . ' <br />I <br />RWC Water Supply Reliability <br /> 0 Bay Area Water Users Asstlcialìon, Interim Water Shortage Allocation Plan, July 2001. <br /> a Nicole M. SanQkul!a, P. E" Bay Area Water User¡¡ Association (BA WUA). <br />From this information! generated Exhibil 1 sbowing the current level of water slJpply relíabi!ity <br />for RWC, Because the future is unknown, reliability must be expr~sedin prob¡¡biiìstic terms <br />using the b~t infonnatíon avai!¡¡ble. It is importantto ,note that as part orlhe 1984 Master Water <br />Sales Contract RWC has a contracIua1 "water supply II$surance" ofl2,243 acre. feet per year <br />(AFY). However, this amolJnt1'elates to aJegal definition and not an absolute volume <br />guaranteed. In times of shortage, the SFPUC wi ) provîde less than thcassura!1c.e åS iJlustrâted in <br />Exhibit I. <br />Exhibit 1. SFPUC Water Supply Reliabillty <br /> (1) (2) (3) (4) (51 (6) <br /> Holch HetCIoy BAWUA RWC RWC Future <br /> By....m Demå"'~ Demand Doma/U! Allooou... HI"toricel Probability <br />Scenario culbàck Cutback CutbaCk AF"f Probliblll1y 2010 <br />1 0% 0.0% 0.0% >12.243 NA NA <br />2 - .11.4% -12.2% 11,!;S4 NA NA <br />3 -10% -12.0% -17.5% 10.891 7.6% 6.3% <br />4 -15% -16..2% -23,3% 10,124 NA 5.1% <br />5 .20% -23;6% -2U% 9.456 2.5% 2,5% <br />6 >.20% >-23.6% >-26,4% ~.456 0.0% 2.5% <br />{t¡ The ¡"...... We... Sltqtra¡¡e ~Iìon P1an 0!Id",.." ....,,~ .,.;do cut!>acks ",,1020%. <br />(21 VOIo"'P"'Vided Þy NIcoJ. Saooi<otlo, a.yAtee Wator U""A""cialion. <br />(3) s.ood On _.....l1mmN",*, SaodIWIio. updalo<! will> FY 1999100 and 200001 waler ""0. <br />(4) - on FY2OOOIO1 wa... ..._s. <br />(~)_ilyof__oOtQl~ng¡"agiY"'__0.hydn>liogylrom19211o1001i. <br /> Inlorm- lakonlrom A¡¡ure:z.s In SFP\!C WatorSoppl\' Moster Pf8r1. A¡¡ri1201llt <br /> 11'Ieprobabllily 010 5%"" 15% clllbs"... "'" addr"..... I\OricO """noel.. noI...DoòIo {NA . <br />(6) Fut\¡re probabilillOs buodcnlnlorpalal1o<toftlìo260....Wi MaD d"""'" .-In",""tor_. <br />Exhibit 1 showS that the ftt:quency and IIUIgnitude of water use cutbacks. From a statistical <br />perspective, ¡¡iverl currentcircUtnSlaIlccs in a given year there is a: <br /> 0 89.9% chance of no water shortage or 15% cutback. UnfortUnately, the SFPUC master <br /> plan did not identify the probability ora 5% cuthåck. For San FtaI1cÎS¡:o and most <br /> BA WUA agencies, a 5% system cutback will be a minor event met with voluntary <br /> conservation. FOr RWC, in conllJ$t, a 5% system cutback wiu lead to a 12.2% RWC <br /> cutback-a significant event requiring some active conservation intervenlio~, <br /> Page Z <br />