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Mountains are highly successful. Tne evaluation results for the Lake Almanor. Uppcr American, Mokelumnc River, Kings River, Kern River, Kaweah River and Eastcrn Sierra operational secding programs suggest \vith grcat statistical confidence that seeding incrcascd the strcamflow in these watersheds by sii"..able amounts. Taking into account the fact thai the evaluation targets chosen to rcpresent these watershcds may not have been the locations best targeted by the sccding, it is possible that thc actual effects of seeding and their statistical support may be even larger than that presented in this papcr. d. It was found that the seeding effectiveness in the 7 watersheds has been decreasing since about 1990, give or take a year or two. e. It was found that the meteorological conditions upon which the seeding procedures used in the opcrational sceding programs have bcen changing so as to produce a general wanning of the stann cnvironment. It is speculated that this wanning may have rendercd the ground~releascd silver iodidc less and less effcctive over time, thereby contributing to the observcd decrease in seeding effcctiveness. It is spcculated that the gcneral ".:anning of the stoml environment may be a contributing factor to the decreasc in seeding eflt."Ctiveness since about 1990 but Ilot necessarily the only contributing factor. Furthcr study of this and other potential causes mentioncd earlier is necdcd to clarify and possibly correct thc problem, f. Morc in-depth physical studies should be conducted of this and other potcntial contributing factors to the dccrcase in secding eflectivcncss with the aim of making adjustments to the secding procedures. ifpossiblc, that restorc the seeding ctTectivencss ofthesc programs to thc sllccessfullcvels they achieved earlier. g. The findings in this papcr does not, by itselC constitute "scicntitic proof' that sccding of orographic clouds incrcases precipitation. snowpack and subsequcnt streamllow; however, they ccrtainly constitute "ample evidencc" to justify operational application of this sceding technology (Gars tang et. a!., 2005). The estimatcd ctTects of secding should be of considcrable value to the sponsors of the operational cloud seeding programs in detennining the past, present and futurc value of their cloud seeding operations according to risk critcria used in their business operations, As Boe et. al.(2004) state, ..... if a potential sponsor of a cloud sceding program, following careful delibcration, decided they had an 80% likelihood of obtaining a 10% increasc in prccipitation that would yield a benefit/cost ratio of 10/1, they would probably choose to support the program," According to Hcnderson (2003a) all increase in streamllO\v of only 1.5% in the Sierra Ncvada J\tountain \..'atcrsheds would yield a benefit/cost ratio of 1011. 9. Future work The results of this preliminary evaluation ofthc 7 operational cloud seeding programs in the Sierra Nevada Mountains of California provide inccntive to do more in-depth statistical and physical studies to \'alidate and extend the findings. One might suspect and qucstion the results of the evaluation of one operational program: however, thc results of the cvaluation of 7 operational programs showing consistently positive seeding effects is compelling and call not be ignored. The magnitude of thc increases in strcamflow due to secding suggcsted by this preliminary study are, howcver, largcr than one would expect from the results of pre....ious physical studies of the seedability of orographic clouds over the Sierra Nevada Mountains of California and of the problems encountered in the transport and dilTusion of the seeding material to thc right place and at the right time in the clouds (see. e,g.. ~Iarwit/. 1987: Reynolds and Dennis. 1986. Reynolds. 1988. Deshler et. a!., 1990, Reynolds. 1996). Consequently, new statistical and physical studies arc needed to clarify the results and to resolve the uncertainties, 47