ATTACHMENT A: Worst Case Scenario Summary This scenario is intended to represent assumptions with a combined 1 in 100 probability of occurring. • • • Climate change is at the worst end of consideration: -6 weeks peak, 50% combined flow and ET impacts; Weighted average demand growth rate is 1.2%, resulting in a 2065 treated water demand of approximately 6,320 acre-feet; Flow adjustment factors are at their expected values; Total Shortages Below are the shortages to Aspen and instream flows, relative to Aspen’s annual treated water demand Annual Shortages 12,000 10,000 6,000 4,000 2,000 Hydrologic year Annual shortage to Aspen Annual instream flow shortage Aspen's estimated demand 1994 1993 1992 1991 1990 1989 1988 1987 1986 1985 1984 1983 1982 1981 1980 1979 1978 1977 1976 1975 1974 1973 1972 1971 1970 Acre-feet 8,000 Municipal Shortages Municipal and Industrial (M&I) water refers to the portion of Aspen’s water system that is diverted to supply its residential, commercial and industrial customer needs. Assuming M&I is the higher priority and instream flows take the first “hit”, there are still M&I shortages in 19 of 25 years, with 4 of those years with shortages of 1,000 acre-feet or more Number of years with M&I shortages Number of years M&I shortage exceeds 100 acre-feet Number of years M&I shortage exceeds 1000 acre-feet Number of years M&I shortage exceeds 2000 acre-feet Number of years M&I shortage exceeds 3000 acre-feet Number of years M&I shortage exceeds 5000 acre-feet 19 15 4 1 0 0 Instream Flows The following graphic summarizes instream flow levels that either meet or fall below instream flow decrees, over the 1970 to 1994 hydrologic period of record. The combined flows of Castle and Maroon Creek should total 27.3 cfs to meet instream flow levels (13.3 cfs for Castle Creek; 14.0 cfs for Maroon Creek). Impacts to the creeks increase in severity with darkening colors. KEY <=0 Combined 0.01-5 Castle/Maroon 5.01-10 Flow 10.01-15 in 15.01-20 CFS 20.01-27.3 CY Wk WY Wk 1969 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 Jan Feb Mar Apr May Jun Jul Aug Sep 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 1 3 17 16 17 16 14 14 15 16 19 26 34 46 59 87 ## ## ## ## ## ## ## ## ## 67 98 94 60 38 21 14 14 13 8 16 10 35 46 29 16 15 18 18 20 19 19 19 19 18 20 23 30 46 79 ## ## ## ## ## ## ## ## ## 60 80 ## 79 56 47 37 21 19 13 9 15 19 19 7 3 -1 4 15 16 17 16 15 14 15 15 18 24 36 59 87 ## ## ## ## ## ## ## ## ## ## ## 48 17 7 -4 -9 ## -4 -6 -6 -7 -7 1 -3 -0 -3 -0 15 18 15 14 13 12 12 11 14 19 25 40 59 87 ## ## ## ## ## ## ## ## 74 ## 54 ## 69 55 41 23 29 30 18 14 10 9 6 -0 -2 2 17 16 16 15 14 13 12 13 14 19 28 42 66 99 ## ## ## ## ## ## ## ## 94 ## 95 44 21 1 1 -3 -0 -0 -6 ## ## ## ## ## ## -8 16 14 14 14 14 14 14 13 16 22 26 42 55 86 ## ## ## ## ## ## ## 75 84 60 37 54 ## ## 97 47 42 29 22 14 7 7 6 2 -3 -1 15 14 15 14 13 13 15 15 18 23 32 48 70 ## ## ## ## ## ## ## ## ## ## 77 27 19 20 7 2 -3 4 -1 -4 -5 -6 -6 -8 -9 -5 1 12 12 11 11 10 9 9 10 11 15 21 34 52 82 ## ## ## ## ## ## 88 ## 75 14 ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## 8 8 8 8 7 7 8 9 10 14 19 31 48 75 ## ## ## ## ## ## ## ## ## ## ## 85 53 51 47 22 19 6 2 -6 -8 -4 -7 -9 ## -7 10 10 10 10 10 10 10 11 13 18 25 39 58 85 ## ## ## ## ## ## ## ## ## ## 77 ## 92 73 71 63 47 36 39 20 9 7 -1 -4 -5 -1 14 13 14 13 13 13 14 15 17 22 29 44 60 87 ## ## ## ## ## ## ## ## ## ## ## 94 68 48 27 19 21 14 14 8 7 9 14 2 -1 4 19 18 16 14 13 12 11 12 14 18 24 37 54 82 ## ## ## ## ## ## ## ## ## 80 18 -1 -3 -8 ## ## ## ## ## ## ## -5 -5 -8 ## -5 6 7 9 14 14 14 14 16 19 22 30 40 58 86 ## ## ## ## ## ## ## ## ## ## 83 86 73 59 58 65 69 42 38 25 17 18 17 20 22 24 18 17 18 18 17 16 16 17 19 25 34 51 73 ## ## ## ## ## ## ## ## ## ## 95 ## ## ## ## 79 60 93 88 59 44 38 29 12 6 3 9 21 20 18 19 20 19 20 21 22 26 33 53 80 ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## 94 69 69 64 54 43 30 26 23 26 32 30 29 29 28 27 27 26 27 33 44 65 87 ## ## ## ## ## ## ## ## ## ## ## ## 92 90 73 59 44 49 42 25 18 16 24 19 19 13 16 24 24 23 23 22 21 21 22 24 32 46 72 ## ## ## ## ## ## ## ## ## ## ## ## ## 99 ## 71 57 42 39 36 33 42 35 28 29 21 21 23 24 23 21 19 18 18 19 18 20 31 36 56 73 ## ## ## ## ## ## ## ## ## ## ## 56 23 20 10 6 13 23 23 14 21 6 6 -1 -3 -5 0 18 18 17 15 16 17 17 19 24 29 35 58 91 ## ## ## ## ## ## ## ## ## ## 82 46 24 9 -7 ## ## -0 -5 -8 -7 -7 -6 -3 -3 -5 -1 14 14 15 16 16 15 16 18 18 20 31 47 76 ## ## ## ## ## ## ## ## ## ## 82 60 31 36 22 4 19 20 8 4 -5 -9 -6 -8 -7 -7 -3 9 10 9 9 10 11 11 13 18 21 28 44 71 ## ## ## ## ## ## ## ## ## ## ## 67 38 20 11 -5 -9 -7 ## -7 ## ## -9 ## -8 ## -1 13 13 12 10 11 11 12 11 13 18 23 36 53 ## ## ## ## ## ## ## ## ## ## ## 93 44 47 32 19 10 13 6 1 -4 -4 3 9 4 -2 7 16 15 16 14 14 15 15 16 18 21 31 49 75 ## ## ## ## ## ## ## ## ## 71 65 51 34 29 26 11 15 10 14 7 9 10 8 -2 2 0 3 18 19 20 19 19 19 20 22 25 30 40 60 98 ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## 72 56 70 66 46 39 31 31 22 14 8 10 20 18 19 17 14 16 16 17 19 22 28 40 58 83 ## ## ## ## ## ## ## ## ## ## 89 34 17 2 -5 -7 1 -0 -1 -7 -7 2 -5 -6 -8 Oct 41 42 2 3 1 14 13 25 1 16 2 23 -1 12 -8 7 -2 13 -2 11 ## 0 -9 5 -3 12 2 17 -6 10 17 29 7 21 23 33 18 28 20 32 -1 14 -4 9 -6 8 -1 12 2 14 0 14 10 24 43 4 13 24 15 20 11 8 12 9 0 6 12 15 9 25 19 32 26 29 14 7 6 11 12 13 21 44 5 21 31 23 25 19 18 20 17 9 14 20 23 18 31 28 37 34 37 24 16 14 19 21 23 29 45 6 20 30 22 23 19 17 19 15 8 14 20 22 17 28 27 35 32 33 23 15 14 18 20 22 27 Nov 46 47 7 8 19 18 27 25 20 19 20 19 17 17 17 17 18 17 14 13 7 7 14 13 17 15 20 18 15 14 24 23 25 23 34 32 29 29 30 28 19 16 16 16 13 13 16 15 19 19 20 18 25 23 48 9 17 24 19 18 16 17 16 13 7 13 14 19 14 22 22 31 29 27 16 15 13 14 19 17 22 49 10 16 22 17 16 15 17 16 13 6 11 14 18 12 20 21 30 26 26 15 13 12 14 18 17 21 Dec 50 51 11 12 15 15 21 21 16 15 17 16 15 14 16 15 15 15 13 12 7 6 12 12 12 12 18 17 12 11 19 19 20 19 30 29 24 24 24 23 14 17 14 14 11 10 16 12 16 17 17 17 19 17 52 13 14 19 15 16 15 15 15 12 7 11 13 18 7 17 20 30 23 22 16 14 9 12 16 18 19