20251223Exhibit 5.pdf

Intermountain Gas Company
Avoided Cost Model
2025 — 2030
INTEPAOUNTAIN `�'
GAS COMPANY
A Subsidiary of MDU Resources Group, Inc.
In the Community to Serve'
Exhibit No. 5

INTERMOUNTAIN GAS COMPANY
Avoided Cost by Year
Line Nominal Cost Real Percent Real Cost Present Avoided Cost
No. Year Per Therml'l Adjustment[2] Per Therm Value[3] Per Therm[4]
(a) (b) (c) (d) (e) (f)
1 2025 $ 0.59 $ 0.59 $ 0.57 $ 0.59
2 2026 0.79 29.50% 0.76 1.29 0.67
3 2027 0.80 -2.05% 0.74 1.98 0.70
4 2028 0.81 -2.76% 0.72 2.63 0.70
5 2029 0.81 -4.59% 0.69 3.23 0.70
6 2030 0.81 -3.65% 0.67 3.80 0.69
7 2031 0.83 -0.86% 0.66 4.35 0.69
8 2032 0.88 1.37% 0.67 4.89 0.69
9 2033 0.93 1.82% 0.68 5.43 0.69
10 2034 0.99 2.02% 0.69 5.96 0.69
11 2035 1.05 2.03% 0.71 6.49 0.69
12 2036 1.10 1.15% 0.72 7.01 0.69
13 2037 1.14 -0.80% 0.71 7.52 0.69
14 2038 1.19 0.94% 0.72 8.01 0.69
15 2039 1.26 1.66% 0.73 8.50 0.70
16 2040 1.36 3.37% 0.75 9.00 0.70
17 2041 1.41 0.08% 0.75 9.48 0.70
18 2042 1.50 2.08% 0.77 9.96 0.70
19 2043 1.57 0.96% 0.78 10.43 0.71
20 2044 1.70 3.69% 0.81 10.90 0.71
21 2045 1.80 2.31% 0.83 11.38 0.72
22 2046 1.89 0.56% 0.83 11.84 0.72
23 2047 1.97 0.56% 0.83 12.29 0.72
24 2048 2.06 0.56% 0.84 12.74 0.73
25 2049 2.16 0.57% 0.84 13.17 0.73
26 2050 2.26 0.57% 0.85 13.60 0.73
27 2051 2.36 0.57% 0.85 14.02 0.74
28 2052 2.47 0.57% 0.86 14.43 0.74
29 2053 2.58 0.57% 0.86 14.83 0.74
30 2054 2.70 0.57% 0.87 15.22 0.74
NOTES
I'] See Page 2, Column (e).
[21 The year over year percentage change in Column (b), adjusted by the inflation assumption on
Page 11, Line 4, Column (b).
[31 The cumulative present value of Column (d) is calculated using the real discount rate on
Page 11, Line 5, Column (b).
[41 Levelized avoided cost of Column (e) computed with the real discount rate on
Page 11, Line 5, Column (b).
2

INTERMOUNTAIN GAS COMPANY
Nominal Avoided Cost by Year
Line Commodity Variable Distribution Transportation Total
No. Year Cost['][2] Cost[3] Cost[4] Cost[5]
(a) (b) (c) (d) (e)
1 2025 $ 0.35 $ - $ 0.24 $ 0.59
2 2026 0.54 - 0.25 0.79
3 2027 0.55 - 0.26 0.80
4 2028 0.54 - 0.27 0.81
5 2029 0.53 - 0.28 0.81
6 2030 0.52 - 0.29 0.81
7 2031 0.53 - 0.30 0.83
8 2032 0.56 - 0.31 0.88
9 2033 0.60 - 0.33 0.93
10 2034 0.65 - 0.34 0.99
11 2035 0.69 - 0.35 1.05
12 2036 0.73 - 0.37 1.10
13 2037 0.75 - 0.38 1.14
14 2038 0.80 - 0.40 1.19
15 2039 0.85 - 0.41 1.26
16 2040 0.93 - 0.43 1.36
17 2041 0.96 - 0.45 1.41
18 2042 1.03 - 0.47 1.50
19 2043 1.09 - 0.48 1.57
20 2044 1.19 - 0.50 1.70
21 2045 1.28 - 0.52 1.80
22 2046 1.34 - 0.54 1.89
23 2047 1.41 - 0.57 1.97
24 2048 1.48 - 0.59 2.06
25 2049 1.55 - 0.61 2.16
26 2050 1.62 - 0.64 2.26
27 2051 1.70 - 0.66 2.36
28 2052 1.78 - 0.69 2.47
29 2053 1.87 - 0.72 2.58
30 2054 1.96 - 0.74 2.70
NOTES
See Pages 3-9, Column (f). Nominalized then divided by 10 to convert units from dekatherms
to therms.
[21 Annual growth after 2043 is tied to yearly percentage change of the prior period.
[31 Placeholder value of zero until a Variable Distribution Cost methodology is developed.
[41 See Page 10, Line 8, Column (d). Annual growth is tied to inflation assumption
from Page 11, Line 4, Column (b).
151 Sum of Columns (b)-(d).
3

INTERMOUNTAIN GAS COMPANY
Commodity Cost
Line Heating Weighted Basin HDD HDD Commodity
No. Year Month Price Forecasti'l Weighf'l Factor[3] Cost
(a) (b) (c) (d) (e) (f)
1 2025 10 $ 2.18 3% $ 0.07
2 2025 11 4.08 8% 0.33
3 2025 12 4.83 16% 0.76
4 2025 1 4.27 19% 0.82
5 2025 2 3.63 16% 0.59
6 2025 3 3.38 15% 0.52
7 2025 4 1.76 10% 0.18
8 2025 5 1.35 7% 0.09
9 2025 6 1.88 4% 0.07
10 2025 7 2.64 1% 0.02
11 2025 8 3.25 0% 0.00
12 2025 9 3.05 1% 0.02 $ 3.47
13 2026 10 3.28 3% 0.11
14 2026 11 4.65 8% 0.38
15 2026 12 6.98 16% 1.10
16 2026 1 7.20 19% 1.38
17 2026 2 6.40 16% 1.04
18 2026 3 3.82 15% 0.59
19 2026 4 2.89 10% 0.29
20 2026 5 2.46 7% 0.17
21 2026 6 2.79 4% 0.10
22 2026 7 3.35 1% 0.03
23 2026 8 3.43 0% 0.00
24 2026 9 3.50 1% 0.02 $ 5.20
25 2027 10 3.61 3% 0.12
26 2027 11 4.75 8% 0.39
27 2027 12 6.81 16% 1.07
28 2027 1 7.09 19% 1.36
29 2027 2 5.83 16% 0.94
30 2027 3 3.60 15% 0.56
31 2027 4 2.76 10% 0.28
32 2027 5 2.67 7% 0.18
33 2027 6 2.78 4% 0.10
34 2027 7 3.34 1% 0.03
35 2027 8 3.42 0% 0.00
36 2027 9 3.45 1% 0.02 $ 5.05
NOTES
['I Weighted average price forecast for AECO, Sumas, and Rockies supply basins.
[21 Monthly HDD65 weighting. Based on a normal weather year.
[31 Column (c)times Column (d).
4

INTERMOUNTAIN GAS COMPANY
Commodity Cost
Line Heating Weighted Basin HDD HDD Commodity
No. Year Month Price Forecasti'l Weighf'l Factor[3] Cost
(a) (b) (c) (d) (e) (f)
1 2028 10 $ 3.26 3% $ 0.11
2 2028 11 4.80 8% 0.39
3 2028 12 6.59 16% 1.03
4 2028 1 6.55 19% 1.26
5 2028 2 5.54 16% 0.90
6 2028 3 3.38 15% 0.52
7 2028 4 2.82 10% 0.28
8 2028 5 2.81 7% 0.19
9 2028 6 2.91 4% 0.10
10 2028 7 3.35 1% 0.03
11 2028 8 3.43 0% 0.00
12 2028 9 3.46 1% 0.02 $ 4.84
13 2029 10 3.30 3% 0.11
14 2029 11 4.68 8% 0.38
15 2029 12 5.98 16% 0.94
16 2029 1 5.59 19% 1.07
17 2029 2 5.00 16% 0.81
18 2029 3 3.54 15% 0.55
19 2029 4 2.92 10% 0.29
20 2029 5 2.95 7% 0.20
21 2029 6 2.99 4% 0.11
22 2029 7 3.17 1% 0.03
23 2029 8 3.24 0% 0.00
24 2029 9 3.33 1% 0.02 $ 4.51
25 2030 10 3.45 3% 0.11
26 2030 11 4.78 8% 0.39
27 2030 12 5.18 16% 0.81
28 2030 1 4.96 19% 0.95
29 2030 2 4.35 16% 0.71
30 2030 3 3.88 15% 0.60
31 2030 4 3.08 10% 0.31
32 2030 5 3.12 7% 0.22
33 2030 6 3.10 4% 0.11
34 2030 7 3.19 1% 0.03
35 2030 8 3.26 0% 0.00
36 2030 9 3.39 1% 0.02 $ 4.26
NOTES
['I Weighted average price forecast for AECO, Sumas, and Rockies supply basins.
[21 Monthly HDD65 weighting. Based on a normal weather year.
[31 Column (c)times Column (d).
5

INTERMOUNTAIN GAS COMPANY
Commodity Cost
Line Heating Weighted Basin HDD HDD Commodity
No. Year Month Price Forecasti'l Weighf'l Factor[3] Cost
(a) (b) (c) (d) (e) (f)
1 2031 10 $ 3.56 3% $ 0.11
2 2031 11 4.71 8% 0.38
3 2031 12 5.03 16% 0.79
4 2031 1 4.84 19% 0.93
5 2031 2 4.33 16% 0.70
6 2031 3 3.83 15% 0.59
7 2031 4 3.13 10% 0.31
8 2031 5 3.12 7% 0.22
9 2031 6 3.11 4% 0.11
10 2031 7 3.20 1% 0.03
11 2031 8 3.26 0% 0.00
12 2031 9 3.39 1% 0.02 $ 4.20
13 2032 10 3.58 3% 0.12
14 2032 11 4.69 8% 0.38
15 2032 12 5.05 16% 0.79
16 2032 1 4.99 19% 0.96
17 2032 2 4.48 16% 0.73
18 2032 3 3.96 15% 0.61
19 2032 4 3.20 10% 0.32
20 2032 5 3.18 7% 0.22
21 2032 6 3.17 4% 0.11
22 2032 7 3.25 1% 0.03
23 2032 8 3.33 0% 0.00
24 2032 9 3.47 1% 0.02 $ 4.29
25 2033 10 3.66 3% 0.12
26 2033 11 4.81 8% 0.39
27 2033 12 5.20 16% 0.82
28 2033 1 5.09 19% 0.98
29 2033 2 4.58 16% 0.74
30 2033 3 4.12 15% 0.64
31 2033 4 3.33 10% 0.33
32 2033 5 3.31 7% 0.23
33 2033 6 3.28 4% 0.12
34 2033 7 3.37 1% 0.03
35 2033 8 3.46 0% 0.00
36 2033 9 3.59 1% 0.02 $ 4.41
NOTES
['I Weighted average price forecast for AECO, Sumas, and Rockies supply basins.
[21 Monthly HDD65 weighting. Based on a normal weather year.
[31 Column (c)times Column (d).
6

INTERMOUNTAIN GAS COMPANY
Commodity Cost
Line Heating Weighted Basin HDD HDD Commodity
No. Year Month Price Forecasti'l Weighf'l Factor[3] Cost
(a) (b) (c) (d) (e) (f)
1 2034 10 $ 3.81 3% $ 0.12
2 2034 11 4.99 8% 0.41
3 2034 12 5.37 16% 0.84
4 2034 1 5.25 19% 1.01
5 2034 2 4.73 16% 0.77
6 2034 3 4.26 15% 0.66
7 2034 4 3.39 10% 0.34
8 2034 5 3.37 7% 0.23
9 2034 6 3.35 4% 0.12
10 2034 7 3.45 1% 0.03
11 2034 8 3.53 0% 0.00
12 2034 9 3.66 1% 0.02 $ 4.55
13 2035 10 3.83 3% 0.12
14 2035 11 5.08 8% 0.41
15 2035 12 5.47 16% 0.86
16 2035 1 5.43 19% 1.04
17 2035 2 4.90 16% 0.79
18 2035 3 4.46 15% 0.69
19 2035 4 3.51 10% 0.35
20 2035 5 3.46 7% 0.24
21 2035 6 3.43 4% 0.12
22 2035 7 3.55 1% 0.03
23 2035 8 3.64 0% 0.00
24 2035 9 3.77 1% 0.02 $ 4.69
25 2036 10 3.90 3% 0.13
26 2036 11 5.23 8% 0.43
27 2036 12 5.66 16% 0.89
28 2036 1 5.51 19% 1.06
29 2036 2 4.97 16% 0.80
30 2036 3 4.51 15% 0.70
31 2036 4 3.52 10% 0.35
32 2036 5 3.47 7% 0.24
33 2036 6 3.44 4% 0.12
34 2036 7 3.54 1% 0.03
35 2036 8 3.65 0% 0.00
36 2036 9 3.79 1% 0.02 $ 4.77
NOTES
['I Weighted average price forecast for AECO, Sumas, and Rockies supply basins.
[21 Monthly HDD65 weighting. Based on a normal weather year.
[31 Column (c)times Column (d).

INTERMOUNTAIN GAS COMPANY
Commodity Cost
Line Heating Weighted Basin HDD HDD Commodity
No. Year Month Price Forecasti'l Weighf'l Factor[3] Cost
(a) (b) (c) (d) (e) (f)
1 2037 10 $ 3.93 3% $ 0.13
2 2037 11 5.20 8% 0.42
3 2037 12 5.62 16% 0.88
4 2037 1 5.44 19% 1.04
5 2037 2 4.89 16% 0.79
6 2037 3 4.47 15% 0.69
7 2037 4 3.45 10% 0.35
8 2037 5 3.39 7% 0.24
9 2037 6 3.36 4% 0.12
10 2037 7 3.44 1% 0.03
11 2037 8 3.54 0% 0.00
12 2037 9 3.70 1% 0.02 $ 4.72
13 2038 10 3.88 3% 0.13
14 2038 11 5.18 8% 0.42
15 2038 12 5.59 16% 0.88
16 2038 1 5.58 19% 1.07
17 2038 2 4.99 16% 0.81
18 2038 3 4.53 15% 0.70
19 2038 4 3.58 10% 0.36
20 2038 5 3.48 7% 0.24
21 2038 6 3.43 4% 0.12
22 2038 7 3.51 1% 0.03
23 2038 8 3.62 0% 0.00
24 2038 9 3.80 1% 0.02 $ 4.78
25 2039 10 4.02 3% 0.13
26 2039 11 5.29 8% 0.43
27 2039 12 5.71 16% 0.90
28 2039 1 5.74 19% 1.10
29 2039 2 5.10 16% 0.83
30 2039 3 4.62 15% 0.71
31 2039 4 3.69 10% 0.37
32 2039 5 3.60 7% 0.25
33 2039 6 3.55 4% 0.12
34 2039 7 3.62 1% 0.03
35 2039 8 3.76 0% 0.00
36 2039 9 3.94 1% 0.02 $ 4.90
NOTES
['I Weighted average price forecast for AECO, Sumas, and Rockies supply basins.
[21 Monthly HDD65 weighting. Based on a normal weather year.
[31 Column (c)times Column (d).
8

INTERMOUNTAIN GAS COMPANY
Commodity Cost
Line Heating Weighted Basin HDD HDD Commodity
No. Year Month Price Forecasti'l Weighf'l Factor[3] Cost
(a) (b) (c) (d) (e) (f)
1 2040 10 $ 4.21 3% $ 0.14
2 2040 11 5.52 8% 0.45
3 2040 12 5.79 16% 0.91
4 2040 1 6.02 19% 1.16
5 2040 2 5.43 16% 0.88
6 2040 3 4.92 15% 0.76
7 2040 4 3.93 10% 0.39
8 2040 5 3.85 7% 0.27
9 2040 6 3.78 4% 0.13
10 2040 7 3.88 1% 0.04
11 2040 8 4.01 0% 0.00
12 2040 9 4.19 1% 0.02 $ 5.15
13 2041 10 4.44 3% 0.14
14 2041 11 5.82 8% 0.47
15 2041 12 6.04 16% 0.95
16 2041 1 5.90 19% 1.13
17 2041 2 5.33 16% 0.86
18 2041 3 4.82 15% 0.75
19 2041 4 3.88 10% 0.39
20 2041 5 3.81 7% 0.26
21 2041 6 3.75 4% 0.13
22 2041 7 3.84 1% 0.04
23 2041 8 3.98 0% 0.00
24 2041 9 4.15 1% 0.02 $ 5.15
25 2042 10 4.40 3% 0.14
26 2042 11 5.74 8% 0.47
27 2042 12 6.06 16% 0.95
28 2042 1 6.19 19% 1.19
29 2042 2 5.49 16% 0.89
30 2042 3 5.06 15% 0.78
31 2042 4 4.07 10% 0.41
32 2042 5 4.00 7% 0.28
33 2042 6 3.96 4% 0.14
34 2042 7 4.06 1% 0.04
35 2042 8 4.18 0% 0.00
36 2042 9 4.34 1% 0.02 $ 5.31
NOTES
['I Weighted average price forecast for AECO, Sumas, and Rockies supply basins.
[21 Monthly HDD65 weighting. Based on a normal weather year.
[31 Column (c)times Column (d).
9

INTERMOUNTAIN GAS COMPANY
Commodity Cost
Line Heating Weighted Basin HDD HDD Commodity
No. Year Month Price Forecasti'l Weighf'l Factor[3] Cost
(a) (b) (c) (d) (e) (f)
1 2043 10 $ 4.61 3% $ 0.15
2 2043 11 5.84 8% 0.48
3 2043 12 6.13 16% 0.96
4 2043 1 6.24 19% 1.20
5 2043 2 5.60 16% 0.91
6 2043 3 5.12 15% 0.79
7 2043 4 4.11 10% 0.41
8 2043 5 4.06 7% 0.28
9 2043 6 4.03 4% 0.14
10 2043 7 4.12 1% 0.04
11 2043 8 4.26 0% 0.00
12 2043 9 4.40 1% 0.02 $ 5.39
13 2044 10 4.61 3% 0.15
14 2044 11 6.04 8% 0.49
15 2044 12 6.30 16% 0.99
16 2044 1 6.59 19% 1.26
17 2044 2 5.96 16% 0.97
18 2044 3 5.46 15% 0.84
19 2044 4 4.40 10% 0.44
20 2044 5 4.36 7% 0.30
21 2044 6 4.34 4% 0.15
22 2044 7 4.46 1% 0.04
23 2044 8 4.60 0% 0.00
24 2044 9 4.73 1% 0.03 $ 5.67
25 2045 10 4.90 3% 0.16
26 2045 11 6.24 8% 0.51
27 2045 12 6.63 16% 1.04
28 2045 1 6.79 19% 1.30
29 2045 2 6.09 16% 0.99
30 2045 3 5.58 15% 0.86
31 2045 4 4.54 10% 0.46
32 2045 5 4.50 7% 0.31
33 2045 6 4.47 4% 0.16
34 2045 7 4.61 1% 0.04
35 2045 8 4.75 0% 0.00
36 2045 9 4.88 1% 0.03 $ 5.86
NOTES
['I Weighted average price forecast for AECO, Sumas, and Rockies supply basins.
[21 Monthly HDD65 weighting. Based on a normal weather year.
[31 Column (c)times Column (d).
10

INTERMOUNTAIN GAS COMPANY
Avoided Gas Transportation Cost
Line Combined
No. Description IRS GS-1 IRS and GS-1
(a) (b) (c) (d)
1 Gas Transportation Costsill $ 59,611,488 $ 26,143,833 $ 85,755,321
2 Estimated Sales Volumes (10/1/24 - 9/30/25)i21 309,638,180 148,909,066 458,547,246
3 IRS and GS-1 Combined Gas Transportation Cost per Therm $ 0.18702
4 Incremental Gas Transportation Costs[31 $ 4,410,921 $ 1,934,498 $ 6,345,419
5 Normalized Sales Volumes (1/1/23- 12/31/23)[41 297,081,494 145,207,928 442,289,422
6 IRS and GS-1 Combined Gas Transportation Cost per Therm $ 0.01435
7 Gas Transportation Costi5l $ 0.03790
8 Total IRS and GS-1 Combined Gas Transportation Cost per Therm $ 0.23927
NOTES
['I See Case No. INT-G-22-04, Exhibit No. 6, Line 21, Columns (e) and (f).
[21 See Case No. INT-G-22-04, Exhibit No. 6, Line 22, Columns (e) and (f).
[31 See Case No. INT-G-22-04, Exhibit No. 5, the sum of Lines 1-20, Columns (i)and (j).
141 See Case No. INT-G-22-04, Exhibit No. 5, Line 24, Columns (i) and (j).
[51 See Case No. INT-G-22-04, Workpaper No. 8, Page 1.
11

INTERMOUNTAIN GAS COMPANY
Discount Rate
Line
No. Description Value Ratio Weighting W/Tax benefit
(a) (b) (c) (d) (e)
1 Debf'l 4.94% 50% 2.50% 1.98% [21
2 Equityl'l 9.50% 50% 4.80% 4.80%
3 Weighted Average Cost of Capital 6.78%
4 Inflation Assumption 3.99%
5 Real Discount Rate 2.68%
NOTES
['I Costs and weightings from Case No. INT-G-16-02, Order No. 33757.
[21 Tax benefit adjusts for 21% federal tax.
12