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of the cumulative year evaluation results as a function of the cumulative number of operational years should be indicative of a significant change in some aspect of thc mctcorology and/or seeding procedure that atlccted seeding efTectiveness. The results of the cumulative year statistical evaluations fall into two groups. Group I consists of the three operational seeding programs, Lake Almanor, Upper American and Mokelumne Rivcr, that indicated strong positivc seeding effects throughout their period of operations being evaluated with an apparent downward trend in seeding cfTcctiveness during the lattcr part of the evaluation period, Group 2 consists of the four operational seeding programs. Kings River. Kcrn River, Kaweah River, and Eastern Sierra. that indicated \\'eak seeding etTects at the end of their period of opcrations being evaluated but exhibited strong secding efTects carlier in thcir period of opcrations. The result of the cumulative year statistical evaluation of the operational seeding programs Group 1 is shown in Figs, 3a. Also included in Figure 3a is the rcsult for another target in the Lakc Almanor ,..'atershed, the Feather River at OroviUc (f-TO), a gauging station that is dovmstream of FPR. The rccord length for FlO is longer than that for FPR, thereby allowing for a more complete picture of the time evolution of the seeding elTect in the Lake Almanor watershed. It can be seen from Figure 3a that the seeding cfTect at FTO is quite positive but not quite as positive as that at FPR; however, the time evolution of the seeding etlect is similar for both targets. Examination of thc time evolution of thc seeding eflect for FrO and MMF indicates that thcrc has been a slow but steady dccrease in seeding cfTcctiveness starting in the mid- to latc-1980s, Therc was no comparable target with suitable FNF data to verify that thc Upper American also cxperienced a similar decrcase in seeding clYectiveness. 25 ;;- '-- U 20 ~ w '" .s 15 "C . . "' " . 10 . >- . > '" . 5 ., S , u 0 1955 Upper American (SCU) Mokelumne (MMF) lake Aimanor (FPR) lake Almanor (FTO) 1965 1975 1985 1995 2005 Water Year Fig Ja. Tnc cumulative year seeding elTects for the Lake Almanor (FPR and FTO). Upper American (SCU). and Mokelumne River (M\1F) opcrational secding programs as a function of 41