20230222Attachment B.pdf

Avista’s Application to Revise its
Electric and Natural Gas Book
Depreciation Rates
Attachment B:
Depreciation Study Schedule
AVISTA CORPORATION
TABLE 1. SUMMARY OF ESTIMATED SURVIVOR CURVE, NET SALVAGE PERCENT, ORIGINAL COST, BOOK DEPRECIATION RESERVE AND
CALCULATED ANNUAL DEPRECIATION ACCRUALS RELATED TO ELECTRIC, GAS AND COMMON PLANT AS OF DECEMBER 31, 2021
PROBABLE NET ORIGINAL COST BOOK FUTURE CALCULATED COMPOSITE
RETIREMENT SURVIVIOR SALVAGE AS OF DEPRECIATION BOOK ANNUAL ACCRUAL REMAINING DEPRECIABLE GROUP DATE CURVE PERCENT DECEMBER 31, 2021 RESERVE ACCRUALS AMOUNT RATE LIFE(1)(2)(3)(4)(5)(6)(7)(8)(9)=(8)/(5)(10)=(7)/(8)
ELECTRIC PLANT
STEAM PRODUCTION PLANT
310.30 REMOVING OTHER PROPERTY
KETTLE FALLS 12-2038 SQUARE *0 138,174.50 125,750 12,424 731 0.53 17.0
310.40 EASEMENTS, PERMITS
KETTLE FALLS 12-2038 SQUARE *0 289,111.15 13,891 275,220 16,190 5.60 17.0
311.00 STRUCTURES AND IMPROVEMENTS
KETTLE FALLS 12-2038 75-S1.5 *(5)25,288,272.19 20,848,866 5,703,820 348,470 1.38 16.4 COLSTRIP 3 AND COMMON - IDAHO 12-2027 75-S1.5 *(3)20,152,736.08 17,033,081 3,724,237 628,559 3.12 5.9
COLSTRIP 3 AND COMMON - WASHINGTON 12-2025 75-S1.5 *(3)38,012,944.07 33,399,934 5,753,398 1,449,596 3.81 4.0
COLSTRIP 4 - IDAHO 12-2027 75-S1.5 *(4)18,776,415.30 16,470,119 3,057,353 516,203 2.75 5.9 COLSTRIP 4 - WASHINGTON 12-2025 75-S1.5 *(4)35,416,973.94 31,014,115 5,819,538 1,467,440 4.14 4.0
TOTAL ACCOUNT 311.00 137,647,341.58 118,766,116 24,058,346 4,410,268 3.20
311.10 STRUCTURES AND IMPROVEMENTS - LANDFILL KETTLE FALLS 12-2038 55-S3 *0 3,648,851.16 3,038,704 610,147 38,406 1.05 15.9
312.00 BOILER PLANT EQUIPMENT KETTLE FALLS 12-2038 55-R1 *(5)46,801,685.60 30,014,114 19,127,656 1,228,371 2.62 15.6
COLSTRIP 3 AND COMMON - IDAHO 12-2027 55-R1 *(3)30,424,801.13 24,656,421 6,681,124 1,145,757 3.77 5.8
COLSTRIP 3 AND COMMON - WASHINGTON 12-2025 55-R1 *(3)55,960,862.78 48,277,491 9,362,198 2,382,606 4.26 3.9 COLSTRIP 4 - IDAHO 12-2027 55-R1 *(4)21,565,585.25 15,930,270 6,497,938 1,110,174 5.15 5.9
COLSTRIP 4 - WASHINGTON 12-2025 55-R1 *(4)39,391,891.53 29,725,202 11,242,365 2,857,319 7.25 3.9
TOTAL ACCOUNT 312.00 194,144,826.29 148,603,498 52,911,281 8,724,227 4.49
313.00 ENGINES AND ENGINE-DRIVEN GENERATORS COLSTRIP 3 AND COMMON - IDAHO 12-2027 50-R2.5 *(3)175,460.65 12,394 168,331 28,150 16.04 6.0
COLSTRIP 3 AND COMMON - WASHINGTON 12-2025 50-R2.5 *(3)333,122.65 37,119 305,997 76,692 23.02 4.0 COLSTRIP 4 - IDAHO 12-2027 50-R2.5 *(4)11,394.29 7,824 4,026 673 5.91 6.0 COLSTRIP 4 - WASHINGTON 12-2025 50-R2.5 *(4)21,082.72 26,479 (4,553)0 - -
TOTAL ACCOUNT 313.00 541,060.31 83,816 473,801 105,515 19.50
314.00 TURBOGENERATORS KETTLE FALLS 12-2038 37-R0.5 *(5)18,632,088.90 12,184,298 7,379,396 519,785 2.79 14.2
COLSTRIP 3 AND COMMON - IDAHO 12-2027 37-R0.5 *(3)8,330,808.18 6,553,849 2,026,883 357,021 4.29 5.7
COLSTRIP 3 AND COMMON - WASHINGTON 12-2025 37-R0.5 *(3)15,714,353.74 11,703,630 4,482,154 1,166,375 7.42 3.8 COLSTRIP 4 - IDAHO 12-2027 37-R0.5 *(4)6,018,100.91 3,693,446 2,565,379 451,000 7.49 5.7
COLSTRIP 4 - WASHINGTON 12-2025 37-R0.5 *(4)11,361,051.53 6,781,484 5,034,010 1,304,756 11.48 3.9
TOTAL ACCOUNT 314.00 60,056,403.26 40,916,707 21,487,822 3,798,937 6.33
315.00 ACCESSORY ELECTRIC EQUIPMENT
KETTLE FALLS 12-2038 50-S1 *(5)12,596,049.01 7,191,500 6,034,352 393,987 3.13 15.3
COLSTRIP 3 AND COMMON - IDAHO 12-2027 50-S1 *(3)3,875,940.31 2,994,762 997,457 171,477 4.42 5.8 COLSTRIP 3 AND COMMON - WASHINGTON 12-2025 50-S1 *(3)7,383,244.12 5,822,711 1,782,030 453,740 6.15 3.9
COLSTRIP 4 - IDAHO 12-2027 50-S1 *(4)2,677,756.92 2,027,692 757,176 130,650 4.88 5.8
COLSTRIP 4 - WASHINGTON 12-2025 50-S1 *(4)4,986,641.55 3,872,925 1,313,182 335,999 6.74 3.9
TOTAL ACCOUNT 315.00 31,519,631.91 21,909,590 10,884,197 1,485,853 4.71
316.00 MISCELLANEOUS POWER PLANT EQUIPMENT
KETTLE FALLS 12-2038 60-R2 *(5)2,476,959.19 2,016,977 583,830 37,593 1.52 15.5 COLSTRIP 3 AND COMMON - IDAHO 12-2027 60-R2 *(3)3,492,590.38 3,046,999 550,369 93,305 2.67 5.9 COLSTRIP 3 AND COMMON - WASHINGTON 12-2025 60-R2 *(3)6,589,238.92 5,622,305 1,164,611 294,747 4.47 4.0
COLSTRIP 4 - IDAHO 12-2027 60-R2 *(4)1,574,284.71 1,370,875 266,381 45,390 2.88 5.9 COLSTRIP 4 - WASHINGTON 12-2025 60-R2 *(4)2,968,698.76 2,518,314 569,133 144,458 4.87 3.9
TOTAL ACCOUNT 316.00 17,101,771.96 14,575,471 3,134,324 615,493 3.60
TOTAL STEAM PRODUCTION PLANT 445,087,172.12 348,033,543 113,847,562 19,195,620 4.31
Attachment B - Depreciation Summary Schedule
Page 1 of 12
AVISTA CORPORATION
TABLE 1. SUMMARY OF ESTIMATED SURVIVOR CURVE, NET SALVAGE PERCENT, ORIGINAL COST, BOOK DEPRECIATION RESERVE AND
CALCULATED ANNUAL DEPRECIATION ACCRUALS RELATED TO ELECTRIC, GAS AND COMMON PLANT AS OF DECEMBER 31, 2021

PROBABLE NET ORIGINAL COST BOOK FUTURE CALCULATED COMPOSITE
RETIREMENT SURVIVIOR SALVAGE AS OF DEPRECIATION BOOK ANNUAL ACCRUAL REMAINING DEPRECIABLE GROUP DATE CURVE PERCENT DECEMBER 31, 2021 RESERVE ACCRUALS AMOUNT RATE LIFE(1)(2)(3)(4)(5)(6)(7)(8)(9)=(8)/(5)(10)=(7)/(8)

HYDRO PRODUCTION PLANT
330.10 ASSET AGREEMENT - SETTLEMENT
LITTLE FALLS 12-2059 50-SQ 0 4,200,000.00 2,107,100 2,092,900 83,394 1.99 25.1
330.30 REMOVING PROPERTY OF OTHERS
LITTLE FALLS 12-2059 100-R4 *0 13,633.60 10,676 2,958 170 1.25 17.4 LONG LAKE 12-2055 100-R4 *0 171,079.55 109,434 61,645 2,296 1.34 26.8 SPOKANE UPPER FALLS 12-2060 100-R4 *0 63,563.76 54,920 8,644 541 0.85 16.0
NINE MILE 12-2060 100-R4 *0 9,936.75 7,747 2,190 58 0.58 37.8 POST FALLS 12-2060 100-R4 *0 23,166.89 16,851 6,316 320 1.38 19.7 CABINET GORGE 12-2072 100-R4 *0 6,783,236.89 2,524,159 4,259,077 125,202 1.85 34.0
NOXON RAPIDS 12-2079 100-R4 *0 29,413,621.64 9,332,647 20,080,975 512,637 1.74 39.2
TOTAL ACCOUNT 330.30 36,478,239.08 12,056,434 24,421,805 641,224 1.76
330.31 TWIN CREEK CHANNEL RESTORATION
CABINET GORGE 12-2072 100-R4 *0 242,033.02 60,609 181,424 3,623 1.50 50.1
330.40 LAND EASEMENTS
LITTLE FALLS 12-2059 90-R4 *0 3,626.67 3,627 0 0 - - LONG LAKE 12-2055 90-R4 *0 246,562.25 239,896 6,666 298 0.12 22.4 NINE MILE 12-2060 90-R4 *0 979.50 980 0 0 - -
POST FALLS 12-2060 90-R4 *0 2,708,437.11 1,684,647 1,023,791 28,210 1.04 36.3 CABINET GORGE 12-2072 90-R4 *0 365,924.35 165,075 200,850 7,563 2.07 26.6 NOXON RAPIDS 12-2079 90-R4 *0 80,869.91 13,105 67,765 1,251 1.55 54.2
TOTAL ACCOUNT 330.40 3,406,399.79 2,107,329 1,299,072 37,322 1.10
330.41 LAND EASEMENTS - CONSERVATION - HABITAT CABINET GORGE 12-2072 90-R4 *0 1,992,208.04 214,510 1,777,698 35,344 1.77 50.3
NOXON RAPIDS 12-2079 90-R4 *0 982,234.97 212,592 769,643 13,865 1.41 55.5
TOTAL ACCOUNT 330.41 2,974,443.01 427,102 2,547,341 49,209 1.65
331.00 STRUCTURES AND IMPROVEMENTS MONROE STREET 12-2072 110-R1.5 *(7)8,198,986.35 1,831,747 6,941,168 149,638 1.83 46.4
LITTLE FALLS 12-2059 110-R1.5 *(5)5,471,929.54 1,140,980 4,604,546 126,940 2.32 36.3 LONG LAKE 12-2055 110-R1.5 *(6)7,686,252.01 1,466,588 6,680,839 206,700 2.69 32.3
SPOKANE UPPER FALLS 12-2060 110-R1.5 *(6)1,114,579.61 535,115 646,339 17,502 1.57 36.9
NINE MILE 12-2060 110-R1.5 *(4)20,049,059.52 2,189,911 18,661,111 502,464 2.51 37.1 POST FALLS 12-2060 110-R1.5 *(4)6,751,666.16 899,754 6,121,978 164,159 2.43 37.3
CABINET GORGE 12-2072 110-R1.5 *(13)23,434,868.70 5,716,415 20,764,986 446,484 1.91 46.5
NOXON RAPIDS 12-2079 110-R1.5 *(21)21,487,759.85 5,899,734 20,100,455 391,349 1.82 51.4
TOTAL ACCOUNT 331.00 94,195,101.74 19,680,245 84,521,422 2,005,236 2.13
331.10 STRUCTURES AND IMPROVEMENTS - FISH AND WILDLIFE CONSERVATION
LONG LAKE 12-2055 55-S2.5 *(6)66,378.33 64,914 5,447 205 0.31 26.6 POST FALLS 12-2060 55-S2.5 *(4)6,181.09 2,673 3,756 101 1.63 37.2 CABINET GORGE 12-2072 55-S2.5 *(13)31,650.07 11,620 24,144 616 1.95 39.2
NOXON RAPIDS 12-2079 55-S2.5 *(21)1,090,121.07 115,486 1,203,561 26,836 2.46 44.8
TOTAL ACCOUNT 331.10 1,194,330.56 194,693 1,236,908 27,758 2.32
331.20 STRUCTURES AND IMPROVEMENTS - RECREATION
MONROE STREET 12-2072 50-R2.5 *(7)4,037,024.94 660,395 3,659,222 96,265 2.38 38.0
LONG LAKE 12-2055 50-R2.5 *(6)1,720,681.91 398,598 1,425,325 46,217 2.69 30.8 SPOKANE UPPER FALLS 12-2060 50-R2.5 *(6)5,979.70 6,401 (62)0 - -
NINE MILE 12-2060 50-R2.5 *(4)370,751.66 84,116 301,466 8,664 2.34 34.8 POST FALLS 12-2060 50-R2.5 *(4)901,178.74 142,194 795,032 23,316 2.59 34.1 CABINET GORGE 12-2072 50-R2.5 *(13)2,354,042.26 493,559 2,166,509 53,840 2.29 40.2
NOXON RAPIDS 12-2079 50-R2.5 *(21)2,332,309.51 502,199 2,319,895 57,343 2.46 40.5
TOTAL ACCOUNT 331.20 11,721,968.72 2,287,462 10,667,387 285,645 2.44
331.26 STRUCTURES AND IMPROVEMENTS - RECREATION INFORMATION AND EDUCATION
CABINET GORGE 12-2072 50-R3 *(13)37,910.91 18,077 24,763 642 1.69 38.6
NOXON RAPIDS 12-2079 50-R3 *(21)13,605.56 6,099 10,364 289 2.12 35.9
TOTAL ACCOUNT 331.26 51,516.47 24,175 35,127 931 1.81
Attachment B - Depreciation Summary Schedule
Page 2 of 12
AVISTA CORPORATION
TABLE 1. SUMMARY OF ESTIMATED SURVIVOR CURVE, NET SALVAGE PERCENT, ORIGINAL COST, BOOK DEPRECIATION RESERVE AND
CALCULATED ANNUAL DEPRECIATION ACCRUALS RELATED TO ELECTRIC, GAS AND COMMON PLANT AS OF DECEMBER 31, 2021

PROBABLE NET ORIGINAL COST BOOK FUTURE CALCULATED COMPOSITE
RETIREMENT SURVIVIOR SALVAGE AS OF DEPRECIATION BOOK ANNUAL ACCRUAL REMAINING DEPRECIABLE GROUP DATE CURVE PERCENT DECEMBER 31, 2021 RESERVE ACCRUALS AMOUNT RATE LIFE(1)(2)(3)(4)(5)(6)(7)(8)(9)=(8)/(5)(10)=(7)/(8)

332.00 RESERVOIRS, DAMS AND WATERWAYS MONROE STREET 12-2072 110-R1 *(7)9,972,019.53 2,029,327 8,640,734 189,652 1.90 45.6
LITTLE FALLS 12-2059 110-R1 *(5)6,379,552.46 3,299,976 3,398,554 95,345 1.49 35.6 LONG LAKE 12-2055 110-R1 *(6)37,694,874.97 16,270,701 23,685,866 734,546 1.95 32.2 SPOKANE UPPER FALLS 12-2060 110-R1 *(6)7,728,573.39 3,199,661 4,992,627 137,477 1.78 36.3
NINE MILE 12-2060 110-R1 *(4)30,792,771.90 (295,051)32,319,534 886,452 2.88 36.5 POST FALLS 12-2060 110-R1 *(4)24,355,870.11 4,596,675 20,733,430 566,650 2.33 36.6
CABINET GORGE 12-2072 110-R1 *(13)26,840,962.19 10,015,823 20,314,465 459,406 1.71 44.2
NOXON RAPIDS 12-2079 110-R1 *(21)32,600,317.91 13,096,439 26,349,945 553,701 1.70 47.6
TOTAL ACCOUNT 332.00 176,364,942.46 52,213,550 140,435,155 3,623,229 2.05
332.10 RESERVOIRS, DAMS AND WATERWAYS - FISH AND WILDLIFE CONSERVATION
LONG LAKE 12-2055 65-S1.5 *(6)83,780.62 10,152 78,655 2,420 2.89 32.5 NINE MILE 12-2060 65-S1.5 *(4)82,457.93 8,943 76,813 2,092 2.54 36.7 POST FALLS 12-2060 65-S1.5 *(4)1,369,247.82 159,865 1,264,152 34,494 2.52 36.6
CABINET GORGE 12-2072 65-S1.5 *(13)16,353,511.49 4,458,504 14,020,964 335,597 2.05 41.8 NOXON RAPIDS 12-2079 65-S1.5 *(21)2,333,225.37 765,480 2,057,722 46,458 1.99 44.3
TOTAL ACCOUNT 332.10 20,222,223.23 5,402,945 17,498,306 421,061 2.08
332.15 RESERVOIRS, DAMS AND WATERWAYS - FISH AND WILDLIFE CONSERVATION
NINE MILE 12-2060 65-S1.5 *(4)11,034.00 1,291 10,184 279 2.53 36.5 CABINET GORGE 12-2072 65-S1.5 *(13)1,494,661.03 333,197 1,355,770 31,929 2.14 42.5
NOXON RAPIDS 12-2079 65-S1.5 *(21)956,178.75 326,496 830,480 17,935 1.88 46.3
TOTAL ACCOUNT 332.15 2,461,873.78 660,984 2,196,434 50,143 2.04
332.20 RESERVOIRS, DAMS AND WATERWAYS - RECREATION LITTLE FALLS 12-2059 65-S1.5 *(5)14,365.60 10,198 4,886 166 1.16 29.4
LONG LAKE 12-2055 65-S1.5 *(6)105,639.43 102,370 9,608 347 0.33 27.7 NINE MILE 12-2060 65-S1.5 *(4)47,371.90 613 48,653 1,612 3.40 30.2 POST FALLS 12-2060 65-S1.5 *(4)338,870.45 39,247 313,179 9,946 2.94 31.5
CABINET GORGE 12-2072 65-S1.5 *(13)102,570.35 61,556 54,349 1,602 1.56 33.9 NOXON RAPIDS 12-2079 65-S1.5 *(21)67,068.92 25,675 55,478 1,534 2.29 36.2
TOTAL ACCOUNT 332.20 675,886.65 239,659 486,153 15,207 2.25
333.00 TURBINES AND GENERATORS
MONROE STREET 12-2072 70-S0 *(7)11,574,970.98 2,972,505 9,412,714 247,099 2.13 38.1 LITTLE FALLS 12-2059 70-S0 *(5)39,200,539.26 7,020,990 34,139,577 997,073 2.54 34.2
LONG LAKE 12-2055 70-S0 *(6)8,735,798.61 8,604,845 655,101 22,570 0.26 29.0 SPOKANE UPPER FALLS 12-2060 70-S0 *(6)1,181,041.97 1,209,744 42,161 1,203 0.10 35.0 NINE MILE 12-2060 70-S0 *(4)41,134,467.99 (2,102,188)44,882,034 1,302,488 3.17 34.5
POST FALLS 12-2060 70-S0 *(4)2,233,650.87 2,245,416 77,581 2,417 0.11 32.1 CABINET GORGE 12-2072 70-S0 *(13)46,869,962.84 9,665,042 43,298,016 1,096,192 2.34 39.5
NOXON RAPIDS 12-2079 70-S0 *(21)88,822,330.21 23,740,028 83,734,992 1,951,957 2.20 42.9
TOTAL ACCOUNT 333.00 239,752,762.73 53,356,382 216,242,176 5,620,999 2.34
334.00 ACCESSORY ELECTRIC EQUIPMENT MONROE STREET 12-2072 40-S0.5 *(7)3,034,242.49 226,273 3,020,367 113,418 3.74 26.6
LITTLE FALLS 12-2059 40-S0.5 *(5)13,963,868.82 2,732,501 11,929,561 417,552 2.99 28.6 LONG LAKE 12-2055 40-S0.5 *(6)4,504,041.49 2,817,339 1,956,945 71,987 1.60 27.2 SPOKANE UPPER FALLS 12-2060 40-S0.5 *(6)4,298,798.08 1,218,411 3,338,315 127,947 2.98 26.1
NINE MILE 12-2060 40-S0.5 *(4)18,580,449.17 1,839,520 17,484,147 614,603 3.31 28.4 POST FALLS 12-2060 40-S0.5 *(4)2,448,273.68 776,477 1,769,728 61,723 2.52 28.7 CABINET GORGE 12-2072 40-S0.5 *(13)17,382,299.74 4,054,954 15,587,045 471,285 2.71 33.1
NOXON RAPIDS 12-2079 40-S0.5 *(21)19,615,761.09 3,497,046 20,238,025 696,979 3.55 29.0
TOTAL ACCOUNT 334.00 83,827,734.56 17,162,521 75,324,133 2,575,494 3.07
335.00 MISCELLANEOUS POWER PLANT EQUIPMENT
MONROE STREET 12-2072 65-R1 *(7)33,563.70 7,685 28,228 726 2.16 38.9
LITTLE FALLS 12-2059 65-R1 *(5)548,948.45 133,983 442,413 13,202 2.40 33.5 LONG LAKE 12-2055 65-R1 *(6)811,545.53 321,442 538,796 17,878 2.20 30.1
SPOKANE UPPER FALLS 12-2060 65-R1 *(6)104,449.82 42,781 67,936 2,117 2.03 32.1 NINE MILE 12-2060 65-R1 *(4)1,022,150.57 72,764 990,272 29,267 2.86 33.8 POST FALLS 12-2060 65-R1 *(4)809,339.90 139,759 701,955 20,541 2.54 34.2
CABINET GORGE 12-2072 65-R1 *(13)5,320,035.05 2,441,410 3,570,229 84,871 1.60 42.1 NOXON RAPIDS 12-2079 65-R1 *(21)3,353,312.33 1,562,384 2,495,124 58,811 1.75 42.4
TOTAL ACCOUNT 335.00 12,003,345.35 4,722,209 8,834,953 227,413 1.89
Attachment B - Depreciation Summary Schedule
Page 3 of 12
AVISTA CORPORATION
TABLE 1. SUMMARY OF ESTIMATED SURVIVOR CURVE, NET SALVAGE PERCENT, ORIGINAL COST, BOOK DEPRECIATION RESERVE AND
CALCULATED ANNUAL DEPRECIATION ACCRUALS RELATED TO ELECTRIC, GAS AND COMMON PLANT AS OF DECEMBER 31, 2021

PROBABLE NET ORIGINAL COST BOOK FUTURE CALCULATED COMPOSITE
RETIREMENT SURVIVIOR SALVAGE AS OF DEPRECIATION BOOK ANNUAL ACCRUAL REMAINING DEPRECIABLE GROUP DATE CURVE PERCENT DECEMBER 31, 2021 RESERVE ACCRUALS AMOUNT RATE LIFE(1)(2)(3)(4)(5)(6)(7)(8)(9)=(8)/(5)(10)=(7)/(8)

335.10 MISCELLANEOUS POWER PLANT EQUIPMENT - FISH AND WILDLIFE CONSERVATION CABINET GORGE 12-2072 55-R3 *(13)117,435.81 78,870 53,833 1,409 1.20 38.2
NOXON RAPIDS 12-2079 55-R3 *(21)355,980.02 286,047 144,689 4,141 1.16 34.9
TOTAL ACCOUNT 335.10 473,415.83 364,916 198,522 5,550 1.17
335.15 MISCELLANEOUS POWER PLANT EQUIPMENT - FISH AND WILDLIFE CONSERVATION
LONG LAKE 12-2055 55-R3 *(6)14,592.13 472 14,996 456 3.12 32.9
POST FALLS 12-2060 55-R3 *(4)16,925.06 330 17,272 464 2.74 37.2 CABINET GORGE 12-2072 55-R3 *(13)246,707.66 12,982 265,798 5,852 2.37 45.4
NOXON RAPIDS 12-2079 55-R3 *(21)578,629.85 23,277 676,865 14,230 2.46 47.6
TOTAL ACCOUNT 335.15 856,854.70 37,061 974,931 21,002 2.45
335.20 MISCELLANEOUS POWER PLANT EQUIPMENT - RECREATION LONG LAKE 12-2055 55-R3 *(6)25,697.14 223 27,016 818 3.18 33.0
NINE MILE 12-2060 55-R3 *(4)18,741.21 956 18,535 514 2.74 36.1 CABINET GORGE 12-2072 55-R3 *(13)49,308.33 24,533 31,185 711 1.44 43.9 NOXON RAPIDS 12-2079 55-R3 *(21)45,388.32 7,091 47,829 1,082 2.38 44.2
TOTAL ACCOUNT 335.20 139,135.00 32,802 124,565 3,125 2.25
336.00 ROADS, RAILROADS AND BRIDGES MONROE STREET 12-2072 60-S2.5 *(7)50,448.44 14,745 39,235 1,268 2.51 30.9
SPOKANE UPPER FALLS 12-2060 60-S2.5 *(6)508,242.34 74,751 463,986 12,622 2.48 36.8
NINE MILE 12-2060 60-S2.5 *(4)594,870.06 207,948 410,717 13,969 2.35 29.4 POST FALLS 12-2060 60-S2.5 *(4)577,943.72 53,322 547,739 14,583 2.52 37.6
CABINET GORGE 12-2072 60-S2.5 *(13)1,671,012.58 1,128,034 760,210 21,248 1.27 35.8 NOXON RAPIDS 12-2079 60-S2.5 *(21)259,749.63 140,057 174,240 5,835 2.25 29.9
TOTAL ACCOUNT 336.00 3,662,266.77 1,618,856 2,396,127 69,525 1.90
TOTAL HYDRO PRODUCTION PLANT 694,904,473.45 174,757,033 591,714,841 15,767,090 2.27
OTHER PRODUCTION PLANT
341.00 STRUCTURES AND IMPROVEMENTS
KETTLE FALLS 12-2038 55-R4 *(1)9,028.80 3,289 5,830 344 3.81 16.9
NORTHEAST TURBINE 12-2035 55-R4 *(7)751,025.35 779,112 24,485 1,755 0.23 14.0 BOULDER PARK 12-2042 55-R4 *(1)1,273,891.95 598,553 688,078 33,476 2.63 20.6
RATHDRUM TURBINE 12-2034 55-R4 *(4)3,584,501.93 1,913,632 1,814,250 140,604 3.92 12.9
COYOTE SPRINGS 2 12-2043 55-R4 *(3)11,757,925.21 5,786,408 6,324,255 295,913 2.52 21.4
TOTAL ACCOUNT 341.00 17,376,373.24 9,080,994 8,856,898 472,092 2.72
342.00 FUEL HOLDERS, PRODUCERS AND ACCESSORIES
KETTLE FALLS 12-2038 55-R3 *(1)89,232.19 70,508 19,617 1,203 1.35 16.3 NORTHEAST TURBINE 12-2035 55-R3 *(7)36,896.84 36,512 2,967 213 0.58 13.9
BOULDER PARK 12-2042 55-R3 *(1)162,143.44 16,093 147,672 7,159 4.42 20.6
RATHDRUM TURBINE 12-2034 55-R3 *(4)1,695,808.40 1,003,620 760,021 59,745 3.52 12.7 LANCASTER 12-2040 55-R3 *(3)91,977.92 45,642 49,095 2,649 2.88 18.5
COYOTE SPRINGS 2 12-2043 55-R3 *(3)19,000,289.10 10,222,924 9,347,373 448,888 2.36 20.8
TOTAL ACCOUNT 342.00 21,076,347.89 11,395,299 10,326,745 519,857 2.47
343.00 PRIME MOVERS KETTLE FALLS 12-2038 60-S2 *(1)8,670,084.38 6,454,410 2,302,376 140,904 1.63 16.3
NORTHEAST TURBINE 12-2035 60-S2 *(7)9,058,274.22 9,314,957 377,397 27,757 0.31 13.6 BOULDER PARK 12-2042 60-S2 *(1)57,216.28 30,851 26,937 1,342 2.35 20.1 RATHDRUM TURBINE 12-2034 60-S2 *(4)3,658,328.03 2,999,013 805,648 63,599 1.74 12.7
TOTAL ACCOUNT 343.00 21,443,902.91 18,799,230 3,512,358 233,602 1.09
344.00 GENERATORS KETTLE FALLS 12-2038 50-R1 *(1)234,260.93 59,467 177,136 11,036 4.71 16.1
NORTHEAST TURBINE 12-2035 50-R1 *(7)2,856,667.42 2,692,182 364,453 27,540 0.96 13.2
BOULDER PARK 12-2042 50-R1 *(1)31,370,459.06 18,485,718 13,198,446 704,436 2.25 18.7 RATHDRUM TURBINE 12-2034 50-R1 *(4)51,202,472.43 29,047,819 24,202,753 1,975,711 3.86 12.3
LANCASTER 12-2040 50-R1 *(3)208,505.82 98,908 115,853 6,620 3.17 17.5 COYOTE SPRINGS 2 12-2043 50-R1 *(3)153,915,854.36 54,699,583 103,833,747 5,227,712 3.40 19.9
TOTAL ACCOUNT 344.00 239,788,220.02 105,083,676 141,892,388 7,953,055 3.32
Attachment B - Depreciation Summary Schedule
Page 4 of 12
AVISTA CORPORATION
TABLE 1. SUMMARY OF ESTIMATED SURVIVOR CURVE, NET SALVAGE PERCENT, ORIGINAL COST, BOOK DEPRECIATION RESERVE AND
CALCULATED ANNUAL DEPRECIATION ACCRUALS RELATED TO ELECTRIC, GAS AND COMMON PLANT AS OF DECEMBER 31, 2021

PROBABLE NET ORIGINAL COST BOOK FUTURE CALCULATED COMPOSITE
RETIREMENT SURVIVIOR SALVAGE AS OF DEPRECIATION BOOK ANNUAL ACCRUAL REMAINING DEPRECIABLE GROUP DATE CURVE PERCENT DECEMBER 31, 2021 RESERVE ACCRUALS AMOUNT RATE LIFE(1)(2)(3)(4)(5)(6)(7)(8)(9)=(8)/(5)(10)=(7)/(8)

344.01 GENERATORS - SOLAR CENTRAL OPERATIONS FACILITY 12-2029 25-S2.5 *(3)449,172.23 216,225 246,423 31,915 7.11 7.7
BOULDER PARK 12-2042 25-S2.5 *(1)22,481.62 1,845 20,861 1,200 5.34 17.4
TOTAL ACCOUNT 344.01 471,653.85 218,070 267,284 33,115 7.02
345.00 ACCESSORY ELECTRIC EQUIPMENT
KETTLE FALLS 12-2038 30-S0.5 *(1)538,522.64 12,753 531,155 33,547 6.23 15.8
NORTHEAST TURBINE 12-2035 30-S0.5 *(7)1,243,060.53 1,316,097 13,978 1,134 0.09 12.3 BOULDER PARK 12-2042 30-S0.5 *(1)924,803.36 227,080 706,971 40,640 4.39 17.4
RATHDRUM TURBINE 12-2034 30-S0.5 *(4)4,808,069.65 1,251,402 3,748,990 317,971 6.61 11.8
LANCASTER 12-2040 30-S0.5 *(3)308,080.38 22,741 294,581 17,099 5.55 17.2 COYOTE SPRINGS 2 12-2043 30-S0.5 *(3)17,886,372.01 11,301,510 7,121,453 439,978 2.46 16.2
TOTAL ACCOUNT 345.00 25,708,908.57 14,131,584 12,417,128 850,369 3.31
345.01 ACCESSORY ELECTRIC EQUIPMENT - SOLAR CENTRAL OPERATIONS FACILITY 12-2029 25-S2.5 *(3)33,209.41 11,701 22,505 2,961 8.92 7.6
346.00 MISCELLANEOUS POWER PLANT EQUIPMENT NORTHEAST TURBINE 12-2035 35-R2 *(7)398,997.44 416,493 10,434 799 0.20 13.1
BOULDER PARK 12-2042 35-R2 *(1)64,652.42 8,668 56,631 2,924 4.52 19.4
RATHDRUM TURBINE 12-2034 35-R2 *(4)249,472.21 75,249 184,202 14,867 5.96 12.4 COYOTE SPRINGS 2 12-2043 35-R2 *(3)935,172.62 240,666 722,562 41,025 4.39 17.6
TOTAL ACCOUNT 346.00 1,648,294.69 741,077 973,829 59,615 3.62
TOTAL OTHER PRODUCTION PLANT 327,546,910.58 159,461,630 178,269,135 10,124,666 3.09
TRANSMISSION PLANT
350.30 REMOVING PROPERTY OF OTHERS 80-R4 0 1,487,565.91 808,526 679,040 15,519 1.04 43.8
350.40 LAND RIGHTS 80-R4 0 21,370,166.35 6,109,257 15,260,909 252,654 1.18 60.4 352.00 STRUCTURES AND IMPROVEMENTS 65-S2 (15)30,958,188.58 7,747,582 27,854,334 545,668 1.76 51.0 353.00 STATION EQUIPMENT 46-R2 (10)354,761,236.38 95,101,385 295,135,975 8,298,195 2.34 35.6
354.00 TOWERS AND FIXTURES 80-R4 (10)17,278,383.79 10,901,411 8,104,811 189,191 1.09 42.8 355.00 POLES AND FIXTURES 60-R2.5 (40)333,668,354.17 77,105,789 390,029,907 8,017,633 2.40 48.6
356.00 OVERHEAD CONDUCTORS AND DEVICES 60-R3 (30)175,262,336.99 51,880,548 175,960,490 4,425,996 2.53 39.8
357.00 UNDERGROUND CONDUIT 60-R4 0 3,524,684.97 924,722 2,599,963 57,388 1.63 45.3 358.00 UNDERGROUND CONDUCTORS AND DEVICES 50-S3 0 7,295,386.96 881,892 6,413,495 152,088 2.08 42.2
359.00 ROADS AND TRAILS 75-R4 0 2,576,201.29 993,569 1,582,632 31,723 1.23 49.9
TOTAL TRANSMISSION PLANT 948,182,505.39 252,454,682 923,621,556 21,986,055 2.32
DISTRIBUTION PLANT
360.40 LAND - EASEMENTS 75-R4 0 3,919,239.32 387,325 3,531,915 52,468 1.34 67.3 361.00 STRUCTURES AND IMPROVEMENTS 63-S1 (15)28,833,810.29 8,187,808 24,971,074 497,230 1.72 50.2
362.00 STATION EQUIPMENT 43-R1.5 (10)162,535,477.01 46,837,456 131,951,569 4,194,733 2.58 31.5
364.00 POLES, TOWERS AND FIXTURES 63-R3 (60)497,678,991.49 138,251,042 658,035,344 13,408,462 2.69 49.1 365.00 OVERHEAD CONDUCTORS AND DEVICES 65-R3 (55)319,701,302.67 101,368,487 394,168,533 7,856,503 2.46 50.2
366.00 UNDERGROUND CONDUIT 65-S2.5 (25)144,282,581.99 44,284,515 136,068,713 2,626,090 1.82 51.8
367.00 UNDERGROUND CONDUCTORS AND DEVICES 40-S1.5 (25)252,143,399.05 127,247,806 187,931,443 6,132,115 2.43 30.6 368.00 LINE TRANSFORMERS 50-R2.5 (10)308,080,442.02 109,826,359 229,062,127 6,242,843 2.03 36.7
SERVICES369.10 OVERHEAD 70-R4 (35)66,511,466.03 33,730,790 56,059,690 1,103,488 1.66 50.8
369.20 UNDERGROUND - SPOKANE NETWORK 70-R4 (35)8,600,892.21 1,660,864 9,950,340 160,900 1.87 61.8 369.30 UNDERGROUND - OTHER 70-R4 (35)126,203,635.53 47,338,457 123,036,451 2,217,626 1.76 55.5
TOTAL SERVICES 201,315,993.77 82,730,111 189,046,481 3,482,014 1.73
METERS
370.10 IDAHO 12-2028 33-L1.5 (2)24,506,399.42 16,172,372 8,824,155 1,364,365 5.57 6.5 370.30 WASHINGTON STANDARD 12-L2.5 (2)1,027,480.24 296,841 751,189 80,758 7.86 9.3
370.40 WASHINGTON AMI 15-S2.5 (2)59,447,402.71 8,551,329 52,085,022 4,478,602 7.53 11.6
TOTAL METERS 84,981,282.37 25,020,541 61,660,366 5,923,725 6.97
371.00 INSTALLATIONS ON CUSTOMERS' PREMISES - CATALYST BUILDING 35-R3 0 604,986.51 23,632 581,354 17,318 2.86 33.6
ELECTRIC VEHICLE CHARGING STATION371.01 RESIDENTIAL 10-S3 0 2,572,461.22 717,097 1,855,364 279,501 10.87 6.6
371.02 MULTI-UNIT DWELLINGS 10-S3 0 165,896.47 106,800 59,097 12,655 7.63 4.7
TOTAL ELECTRIC VEHICLE CHARGING STATION 2,738,357.69 823,897 1,914,461 292,156 10.67
Attachment B - Depreciation Summary Schedule
Page 5 of 12
AVISTA CORPORATION
TABLE 1. SUMMARY OF ESTIMATED SURVIVOR CURVE, NET SALVAGE PERCENT, ORIGINAL COST, BOOK DEPRECIATION RESERVE AND
CALCULATED ANNUAL DEPRECIATION ACCRUALS RELATED TO ELECTRIC, GAS AND COMMON PLANT AS OF DECEMBER 31, 2021

PROBABLE NET ORIGINAL COST BOOK FUTURE CALCULATED COMPOSITE
RETIREMENT SURVIVIOR SALVAGE AS OF DEPRECIATION BOOK ANNUAL ACCRUAL REMAINING DEPRECIABLE GROUP DATE CURVE PERCENT DECEMBER 31, 2021 RESERVE ACCRUALS AMOUNT RATE LIFE(1)(2)(3)(4)(5)(6)(7)(8)(9)=(8)/(5)(10)=(7)/(8)

STREET LIGHTING AND SIGNAL SYSTEMS373.10 MERCURY VAPOR 33-S1 (15)4,542,176.93 4,650,479 573,024 35,580 0.78 16.1
373.20 UNDERGROUND CONDUCTOR 33-S1 (15)5,767,344.92 2,775,261 3,857,186 155,806 2.70 24.8 373.30 DECORATIVE AND METAL STANDARDS 33-S1 (15)17,164,120.57 6,550,001 13,188,737 531,748 3.10 24.8 373.40 HIGH PRESSURE SODIUM VAPOR 33-S1 (15)29,524,179.93 6,331,375 27,621,432 1,106,794 3.75 25.0
373.50 LED 33-S1 (15)17,970,693.09 3,792,058 16,874,239 586,057 3.26 28.8
TOTAL STREET LIGHTING AND SIGNAL SYSTEMS 74,968,515.44 24,099,174 62,114,618 2,415,985 3.22
TOTAL DISTRIBUTION PLANT 2,081,784,379.62 709,088,152 2,081,037,998 53,141,642 2.55
GENERAL PLANT
390.10 STRUCTURES AND IMPROVEMENTS - COMPANY 50-S1 (5)17,871,784.76 2,401,202 16,364,172 368,082 2.06 44.5
OFFICE FURNITURE AND EQUIPMENT
391.00 FURNITURE AND EQUIPMENT 15-SQ 0 33,038.66 2,141 30,898 2,203 6.67 14.0 391.10 COMPUTER HARDWARE 5-SQ 0 1,636,374.28 613,250 1,023,124 327,303 20.00 3.1
391.12 COMPUTER HARDWARE - AMI 5-SQ 0 326,249.47 163,115 163,134 65,254 20.00 2.5
TOTAL OFFICE FURNITURE AND EQUIPMENT 1,995,662.41 778,506 1,217,156 394,760 19.78
TRANSPORTATION EQUIPMENT
392.20 LIGHT TRUCKS 14-L2.5 10 8,069,708.69 4,208,989 3,053,749 336,680 4.17 9.1
392.30 MEDIUM TRUCKS 17-L2.5 10 25,968,428.69 11,001,930 12,369,656 990,508 3.81 12.5 392.40 HEAVY TRUCKS 20-R4 10 12,764,812.10 4,325,582 7,162,749 503,016 3.94 14.2
392.50 OTHER 16-L2 10 8,290,921.49 3,317,405 4,144,424 392,099 4.73 10.6
TOTAL TRANSPORTATION EQUIPMENT 55,093,870.97 22,853,905 26,730,578 2,222,303 4.03
393.00 STORES EQUIPMENT 25-SQ 0 472,783.36 203,758 269,025 18,912 4.00 14.2
TOOLS, SHOP AND GARAGE EQUIPMENT394.00 TOOLS, SHOP AND GARAGE EQUIPMENT 20-SQ 0 7,396,275.89 2,134,054 5,262,222 369,582 5.00 14.2 394.10 ELECTRIC VEHICLE CHARGER 10-S2.5 0 117,230.09 61,134 56,096 11,147 9.51 5.0
TOTAL TOOLS, SHOP AND GARAGE EQUIPMENT 7,513,505.98 2,195,188 5,318,318 380,729 5.07
LABORATORY EQUIPMENT
395.00 LABORATORY EQUIPMENT 15-SQ 0 2,901,500.20 485,994 2,415,506 193,434 6.67 12.5
395.12 LABORATORY EQUIPMENT - AMI 15-SQ 0 253,883.45 58,519 195,364 16,935 6.67 11.5
TOTAL LABORATORY EQUIPMENT 3,155,383.65 544,513 2,610,870 210,369 6.67
POWER OPERATED EQUIPMENT396.30 MEDIUM TRUCKS 16-L2 0 4,329,903.21 3,171,982 1,157,921 158,345 3.66 7.3 396.40 HEAVY TRUCKS 24-S1 0 21,869,320.06 16,077,964 5,791,356 411,472 1.88 14.1
396.50 OTHER 16-S0 0 4,057,267.11 1,894,977 2,162,290 196,355 4.84 11.0
TOTAL POWER OPERATED EQUIPMENT 30,256,490.38 21,144,923 9,111,567 766,172 2.53
COMMUNICATION EQUIPMENT
397.00 COMMUNICATION EQUIPMENT 15-SQ 0 46,103,096.93 24,744,035 21,359,062 3,075,067 6.67 6.9
397.50 SUB INTEGRATION 15-SQ 0 3,537,825.37 655,984 2,881,841 235,914 6.67 12.2 397.60 DISTRIBUTION 15-SQ 0 563,964.48 41,387 522,577 37,616 6.67 13.9
TOTAL COMMUNCATION EQUIPMENT 50,204,886.78 25,441,406 24,763,480 3,348,597 6.67
398.00 MISCELLANEOUS EQUIPMENT 10-SQ 0 288,548.57 135,498 153,051 28,842 10.00 5.3
TOTAL GENERAL PLANT 166,852,916.86 75,698,901 86,538,217 7,738,766 4.64
TOTAL DEPRECIABLE ELECTRIC PLANT 4,664,358,358.02 1,719,493,940 3,975,029,309 127,953,839 2.74
Attachment B - Depreciation Summary Schedule
Page 6 of 12
AVISTA CORPORATION
TABLE 1. SUMMARY OF ESTIMATED SURVIVOR CURVE, NET SALVAGE PERCENT, ORIGINAL COST, BOOK DEPRECIATION RESERVE AND
CALCULATED ANNUAL DEPRECIATION ACCRUALS RELATED TO ELECTRIC, GAS AND COMMON PLANT AS OF DECEMBER 31, 2021

PROBABLE NET ORIGINAL COST BOOK FUTURE CALCULATED COMPOSITE
RETIREMENT SURVIVIOR SALVAGE AS OF DEPRECIATION BOOK ANNUAL ACCRUAL REMAINING DEPRECIABLE GROUP DATE CURVE PERCENT DECEMBER 31, 2021 RESERVE ACCRUALS AMOUNT RATE LIFE(1)(2)(3)(4)(5)(6)(7)(8)(9)=(8)/(5)(10)=(7)/(8)

GAS PLANT - WASHINGTON AND IDAHO
NATURAL GAS STORAGE AND PROCESSING PLANT
350.20 RIGHTS OF WAY 65-R4 0 66,073.04 30,538 35,535 798 1.21 44.5
STRUCTURES AND IMPROVEMENTS351.10 STRUCTURES AND IMPROVEMENTS 55-R2.5 (5)1,934,672.05 617,856 1,413,550 31,045 1.60 45.5
351.20 COMPRESSOR STATION 55-R2.5 (5)275,254.53 211,229 77,789 3,234 1.17 24.1 351.30 MEASURING AND REGULATING STATION 55-R2.5 (5)52,850.07 41,396 14,096 586 1.11 24.1
351.40 OFFICE 55-R2.5 (5)171,892.07 113,487 67,000 2,276 1.32 29.4
TOTAL STRUCTURES AND IMPROVEMENTS 2,434,668.72 983,968 1,572,435 37,141 1.53
WELLS352.00 STORAGE WELLS 60-R4 0 17,514,187.79 6,392,534 11,121,654 257,465 1.47 43.2
352.20 RESERVOIRS 50-R4 0 203,330.47 100,040 103,290 3,858 1.90 26.8
352.30 NON-RECOVERABLE GAS 50-R4 0 5,359,690.41 3,880,450 1,479,240 45,788 0.85 32.3
TOTAL WELLS 23,077,208.67 10,373,024 12,704,184 307,111 1.33
353.00 LINES 65-R4 0 2,059,776.77 658,349 1,401,428 30,912 1.50 45.3
354.00 COMPRESSOR STATION EQUIPMENT 55-R4 0 14,950,425.57 4,095,122 10,855,304 265,347 1.77 40.9 355.00 MEASURING AND REGULATING EQUIPMENT 35-R3 0 1,559,281.17 900,020 659,261 19,345 1.24 34.1
356.00 PURIFICATION EQUIPMENT 35-S2.5 0 545,142.76 404,807 140,336 8,593 1.58 16.3
357.00 OTHER EQUIPMENT 45-R2 0 2,572,899.06 1,040,300 1,532,599 44,316 1.72 34.6
TOTAL NATURAL GAS STORAGE AND PROCESSING PLANT 47,265,475.76 18,486,129 28,901,082 713,563 1.51
DISTRIBUTION PLANT
374.40 LAND - EASEMENTS 60-R4 0 668,024.19 55,211 612,813 11,343 1.70 54.0
375.00 STRUCTURES AND IMPROVEMENTS 45-R2 0 1,575,588.81 291,324 1,284,265 37,193 2.36 34.5
376.00 MAINS 55-R3 (20)437,133,268.15 130,648,846 393,911,076 9,190,399 2.10 42.9 378.00 MEASURING AND REGULATING EQUIPMENT - GENERAL 32-R2 (15)7,132,736.23 2,326,349 5,876,298 287,503 4.03 20.4
379.00 MEASURING AND REGULATING EQUIPMENT - CITY GATE 37-S0.5 (15)6,602,678.34 2,162,723 5,430,357 208,581 3.16 26.0
380.00 SERVICES 52-R3 (25)321,283,115.49 111,465,916 290,137,978 7,115,867 2.21 40.8
381.00 METERS
IDAHO 35-R1 (3)31,937,722.14 10,715,075 22,180,779 881,397 2.76 25.2 WASHINGTON 35-R1 (3)52,741,984.87 10,165,030 44,159,214 1,636,498 3.10 27.0
WASHINGTON AMI 15-S2.5 (3)26,583,363.26 3,768,633 23,612,231 1,986,240 7.47 11.9
TOTAL METERS 111,263,070.27 24,648,738 89,952,224 4,504,135 4.05
385.00 INDUSTRIAL MEASURING AND REGULATING STATION EQUIPMENT 65-R2.5 (15)4,095,769.59 1,637,452 3,072,683 59,548 1.45 51.6
TOTAL DISTRIBUTION PLANT 889,754,251.07 273,236,558 790,277,694 21,414,569 2.41
GENERAL PLANT
389.42 LAND EASEMENTS 50-R3 0 2,368.16 153 2,215 48 2.03 46.1
390.10 STRUCTURES AND IMPROVEMENTS - COMPANY 30-R3 (5)25,396,990.63 3,026,959 23,639,881 899,941 3.54 26.3 391.10 OFFICE FURNITURE AND EQUIPMENT - COMPUTER HARDWARE 5-SQ 0 143,319.84 68,080 75,240 28,668 20.00 2.6
TRANSPORTATION EQUIPMENT 392.20 LIGHT TRUCKS 14-L2.5 10 6,096,666.67 3,906,438 1,580,562 141,994 2.33 11.1
392.30 MEDIUM TRUCKS 17-L2.5 10 4,873,010.27 3,042,040 1,343,669 99,522 2.04 13.5 392.40 HEAVY TRUCKS 20-R4 10 3,098,038.40 1,477,241 1,310,993 86,722 2.80 15.1 392.50 OTHER 16-L2 10 1,680,103.22 764,833 747,260 68,600 4.08 10.9
TOTAL TRANSPORTATION EQUIPMENT 15,747,818.56 9,190,553 4,982,484 396,838 2.52
393.00 STORES EQUIPMENT 25-SQ 0 222,353.15 43,386 178,967 8,895 4.00 20.1 394.00 TOOLS, SHOP AND GARAGE EQUIPMENT 20-SQ 0 3,414,564.99 1,408,340 2,006,225 170,613 5.00 11.8
395.00 LABORATORY EQUIPMENT 15-SQ 0 160,329.45 60,441 99,889 10,690 6.67 9.3
395.12 LABORATORY EQUIPMENT - AMI 15-SQ 0 40,840.58 9,510 31,331 2,724 6.67 11.5
POWER OPERATED EQUIPMENT
396.40 HEAVY TRUCKS 24-S1 0 2,250,127.78 2,078,213 171,915 11,584 0.51 14.8 396.50 OTHER 16-S0 0 1,979,057.51 1,321,527 657,531 57,753 2.92 11.4
TOTAL POWER OPERATED EQUIPMENT 4,229,185.29 3,399,739 829,446 69,337 1.64
Attachment B - Depreciation Summary Schedule
Page 7 of 12
AVISTA CORPORATION
TABLE 1. SUMMARY OF ESTIMATED SURVIVOR CURVE, NET SALVAGE PERCENT, ORIGINAL COST, BOOK DEPRECIATION RESERVE AND
CALCULATED ANNUAL DEPRECIATION ACCRUALS RELATED TO ELECTRIC, GAS AND COMMON PLANT AS OF DECEMBER 31, 2021

PROBABLE NET ORIGINAL COST BOOK FUTURE CALCULATED COMPOSITE
RETIREMENT SURVIVIOR SALVAGE AS OF DEPRECIATION BOOK ANNUAL ACCRUAL REMAINING DEPRECIABLE GROUP DATE CURVE PERCENT DECEMBER 31, 2021 RESERVE ACCRUALS AMOUNT RATE LIFE(1)(2)(3)(4)(5)(6)(7)(8)(9)=(8)/(5)(10)=(7)/(8)

397.00 COMMUNICATION EQUIPMENT FULLY ACCRUED FULLY ACCRUED 29.12 29 0 0 - -
AMORTIZED 15-SQ 0 884,115.45 400,850 483,265 59,001 6.67 8.2
TOTAL COMMUNICATION EQUIPMENT 884,144.57 400,879 483,265 59,001 6.67
397.12 COMMUNICATION EQUIPMENT - AMI 15-SQ 0 19,942.47 4,649 15,293 1,330 6.67 11.5
TOTAL GENERAL PLANT 50,261,857.69 17,612,689 32,344,236 1,648,085 3.28
TOTAL GAS PLANT - WASHINGTON AND IDAHO 987,281,584.52 309,335,376 851,523,012 23,776,217 2.41
GAS PLANT - ALLOCATED ALL
391.10 OFFICE FURNITURE AND EQUIPMENT - COMPUTER HARDWARE 5-SQ 0 333,341.25 195,625 137,716 66,655 20.00 2.1
TRANSPORTATION EQUIPMENT 392.20 LIGHT TRUCKS 14-L2.5 10 50,237.38 5,687 39,527 3,160 6.29 12.5 392.50 OTHER 16-L2 10 46,950.20 6,893 35,362 2,798 5.96 12.6
TOTAL TRANSPORTATION EQUIPMENT 97,187.58 12,580 74,889 5,958 6.13
394.00 TOOLS, SHOP AND GARAGE EQUIPMENT 20-SQ 0 5,671,193.25 1,743,687 3,927,506 283,456 5.00 13.9 395.00 LABORATORY EQUIPMENT 15-SQ 0 233,215.60 106,892 126,324 15,546 6.67 8.1
397.00 COMMUNICATION EQUIPMENT 15-SQ 0 282,919.85 123,150 159,770 18,869 6.67 8.5
TOTAL GAS PLANT - ALLOCATED ALL 6,617,857.53 2,181,934 4,426,205 390,484 5.90
GAS PLANT - OREGON
NATURAL GAS STORAGE AND PROCESSING PLANT
350.20 RIGHTS OF WAY 65-R4 0 668.75 24 645 12 1.79 53.8
STRUCTURES AND IMPROVEMENTS351.10 STRUCTURES AND IMPROVEMENTS 55-R2.5 (5)24,172.36 740 24,641 534 2.21 46.1
351.20 COMPRESSOR STATION 55-R2.5 (5)264.37 60 218 5 1.89 43.6
351.40 OFFICE 55-R2.5 (5)109,010.23 14,174 100,286 1,892 1.74 53.0
TOTAL STRUCTURES AND IMPROVEMENTS 133,446.96 14,974 125,145 2,431 1.82
WELLS
352.00 STORAGE WELLS 60-R4 0 1,429,957.69 225,365 1,204,593 24,801 1.73 48.6 352.20 RESERVOIRS 50-R4 0 1,464,161.54 289,164 1,174,998 29,786 2.03 39.4 352.30 NON-RECOVERABLE GAS 50-R4 0 450,620.15 119,553 331,067 8,806 1.95 37.6
TOTAL WELLS 3,344,739.38 634,081 2,710,658 63,393 1.90
353.00 LINES 65-R4 0 170,744.96 20,080 150,665 2,787 1.63 54.1 354.00 COMPRESSOR STATION EQUIPMENT 55-R4 0 3,235,659.23 737,036 2,498,624 59,068 1.83 42.3
355.00 MEASURING AND REGULATING EQUIPMENT 35-R3 0 151,373.35 95,213 56,160 1,643 1.09 34.2
356.00 PURIFICATION EQUIPMENT 35-S2.5 0 15,105.70 543 14,562 569 3.77 25.6 357.00 OTHER EQUIPMENT 45-R2 0 128,959.60 15,368 113,592 2,696 2.09 42.1
TOTAL NATURAL GAS STORAGE AND PROCESSING PLANT 7,180,697.93 1,517,319 5,670,051 132,599 1.85
DISTRIBUTION PLANT
374.40 LAND - EASEMENTS 60-R4 0 609,830.41 74,603 535,228 10,174 1.67 52.6
375.00 STRUCTURES AND IMPROVEMENTS 45-R2 0 671,976.30 97,332 574,644 17,232 2.56 33.3 376.00 MAINS 55-R3 (20)269,917,387.93 78,205,577 245,695,289 5,693,794 2.11 43.2
378.00 MEASURING AND REGULATING EQUIPMENT - GENERAL 32-R2 (15)6,117,036.85 1,525,043 5,509,549 245,758 4.02 22.4
379.00 MEASURING AND REGULATING EQUIPMENT - CITY GATE 37-S0.5 (15)3,349,996.01 608,442 3,244,054 107,754 3.22 30.1 380.00 SERVICES 52-R3 (25)130,250,005.03 47,528,304 115,284,202 2,796,194 2.15 41.2
381.00 METERS 35-R1 (3)55,834,070.65 9,053,002 48,456,091 1,864,518 3.34 26.0
385.00 INDUSTRIAL MEASURING AND REGULATING STATION EQUIPMENT 65-R2.5 (15)2,476,547.94 871,753 1,976,277 35,678 1.44 55.4 387.00 OTHER EQUIPMENT 18-SQ 0 539.29 539 0 0 - -
TOTAL DISTRIBUTION PLANT 469,227,390.41 137,964,595 421,275,334 10,771,102 2.30
Attachment B - Depreciation Summary Schedule
Page 8 of 12
AVISTA CORPORATION
TABLE 1. SUMMARY OF ESTIMATED SURVIVOR CURVE, NET SALVAGE PERCENT, ORIGINAL COST, BOOK DEPRECIATION RESERVE AND
CALCULATED ANNUAL DEPRECIATION ACCRUALS RELATED TO ELECTRIC, GAS AND COMMON PLANT AS OF DECEMBER 31, 2021

PROBABLE NET ORIGINAL COST BOOK FUTURE CALCULATED COMPOSITE
RETIREMENT SURVIVIOR SALVAGE AS OF DEPRECIATION BOOK ANNUAL ACCRUAL REMAINING DEPRECIABLE GROUP DATE CURVE PERCENT DECEMBER 31, 2021 RESERVE ACCRUALS AMOUNT RATE LIFE(1)(2)(3)(4)(5)(6)(7)(8)(9)=(8)/(5)(10)=(7)/(8)

GENERAL PLANT
390.10 STRUCTURES AND IMPROVEMENTS - COMPANY 30-R3 (5)4,111,073.85 1,937,601 2,379,026 138,479 3.37 17.2
391.10 OFFICE FURNITURE AND EQUIPMENT - COMPUTER HARDWARE 5-SQ 0 12,222.51 6,111 6,112 2,445 20.00 2.5
TRANSPORTATION EQUIPMENT
392.20 LIGHT TRUCKS 14-L2.5 10 3,285,771.20 1,271,000 1,686,194 180,854 5.50 9.3 392.30 MEDIUM TRUCKS 17-L2.5 10 1,181,335.73 642,544 420,659 34,201 2.90 12.3 392.50 OTHER 16-L2 10 230,653.00 41,739 165,849 13,500 5.85 12.3
TOTAL TRANSPORTATION EQUIPMENT 4,697,759.93 1,955,283 2,272,702 228,555 4.87
393.00 STORES EQUIPMENT 25-SQ 0 20,791.82 17,010 3,782 831 4.00 4.6 394.00 TOOLS, SHOP AND GARAGE EQUIPMENT 20-SQ 0 962,772.04 512,505 450,267 48,105 5.00 9.4
395.00 LABORATORY EQUIPMENT 15-SQ 0 18,586.31 3,104 15,483 1,239 6.67 12.5
396.50 POWER OPERATED EQUIPMENT - OTHER 16-S0 0 43,833.95 44,378 (544)0 - - 397.00 COMMUNICATION EQUIPMENT 15-SQ 0 766,396.89 417,995 348,402 51,090 6.67 6.8
398.00 MISCELLANEOUS EQUIPMENT FULLY ACCRUED FULLY ACCRUED 2,367.16 2,367 0 0 - -
AMORTIZED 10-SQ 0 6,732.60 338 6,395 673 10.00 9.5
TOTAL MISCELLANEOUS EQUIPMENT 9,099.76 2,705 6,395 673 7.40
TOTAL GENERAL PLANT 10,642,537.06 4,896,692 5,481,625 471,417 4.43
TOTAL GAS PLANT - OREGON 487,050,625.40 144,378,605 432,427,010 11,375,118 2.34
TOTAL DEPRECIABLE GAS PLANT 1,480,950,067.45 455,895,915 1,288,376,227 35,541,819 2.40
COMMON PLANT
LAND AND LAND RIGHTS
389.30 REMOVING PROPERTY OF OTHERS 65-R4 0 3,623,332.00 269,423 3,353,909 60,342 1.67 55.6 389.40 LAND EASEMENTS 65-R4 0 139,115.16 38,188 100,928 1,752 1.26 57.6
TOTAL LAND AND LAND RIGHTS 3,762,447.16 307,610 3,454,837 62,094 1.65
390.10 STRUCTURES AND IMPROVEMENTS - COMPANY 50-R2 (10)159,324,485.81 14,881,363 160,375,571 3,907,317 2.45 41.0
OFFICE FURNITURE AND EQUIPMENT
391.00 OFFICE FURNITURE AND EQUIPMENT 15-SQ 0 18,575,154.04 8,200,041 10,375,113 1,238,375 6.67 8.4
391.10 COMPUTER HARDWARE
FULLY ACCRUED FULLY ACCRUED 491,370.77 491,371 0 0 - - AMORTIZED 5-SQ 0 60,938,463.23 31,980,000 28,958,463 12,188,335 20.00 2.4
TOTAL COMPUTER HARDWARE 61,429,834.00 32,471,371 28,958,463 12,188,335 19.84
391.12 COMPUTER HARDWARE - AMI 5-SQ 0 4,963,598.74 3,366,842 1,596,757 992,720 20.00 1.6 391.13 COMPUTER HARDWARE - MDM 5-SQ 0 2,637,348.63 2,110,000 527,349 527,349 20.00 1.0
TOTAL OFFICE FURNITURE AND EQUIPMENT 87,605,935.41 46,148,254 41,457,682 14,946,779 17.06
TRANSPORTATION EQUIPMENT
392.10 AUTOS 11-S2.5 10 84,739.91 124,957 (48,691)0 - - 392.20 LIGHT TRUCKS 14-L2.5 10 4,591,051.25 3,174,966 956,980 85,627 1.87 11.2
392.30 MEDIUM TRUCKS 17-L2.5 10 1,580,580.40 1,068,461 354,061 25,537 1.62 13.9
392.40 HEAVY TRUCKS 20-R4 10 426,366.29 25,177 358,552 25,584 6.00 14.0 392.50 OTHER 16-L2 10 1,115,851.05 679,047 325,219 25,415 2.28 12.8
392.60 AIRPLANE 12-S1.5 30 6,566,805.81 3,824,370 772,394 89,088 1.36 8.7
TOTAL TRANSPORTATION EQUIPMENT 14,365,394.71 8,896,979 2,718,515 251,251 1.75
393.00 STORES EQUIPMENT 25-SQ 0 5,342,387.50 1,472,196 3,870,192 213,648 4.00 18.1 394.00 TOOLS, SHOP AND GARAGE EQUIPMENT 20-SQ 0 16,889,163.44 6,491,747 10,397,417 844,203 5.00 12.3
395.00 LABORATORY EQUIPMENT 15-SQ 0 1,507,790.94 489,589 1,018,202 100,503 6.67 10.1
POWER OPERATED EQUIPMENT
396.30 MEDIUM TRUCKS 16-L2 0 59,501.89 59,502 0 0 - - 396.50 OTHER 16-S0 0 1,930,686.55 1,371,845 558,842 62,577 3.24 8.9
TOTAL POWER OPERATED EQUIPMENT 1,990,188.44 1,431,347 558,842 62,577 3.14
Attachment B - Depreciation Summary Schedule
Page 9 of 12
AVISTA CORPORATION
TABLE 1. SUMMARY OF ESTIMATED SURVIVOR CURVE, NET SALVAGE PERCENT, ORIGINAL COST, BOOK DEPRECIATION RESERVE AND
CALCULATED ANNUAL DEPRECIATION ACCRUALS RELATED TO ELECTRIC, GAS AND COMMON PLANT AS OF DECEMBER 31, 2021

PROBABLE NET ORIGINAL COST BOOK FUTURE CALCULATED COMPOSITE
RETIREMENT SURVIVIOR SALVAGE AS OF DEPRECIATION BOOK ANNUAL ACCRUAL REMAINING DEPRECIABLE GROUP DATE CURVE PERCENT DECEMBER 31, 2021 RESERVE ACCRUALS AMOUNT RATE LIFE(1)(2)(3)(4)(5)(6)(7)(8)(9)=(8)/(5)(10)=(7)/(8)

COMMUNICATION EQUIPMENT397.00 COMMUNICATION EQUIPMENT 15-SQ 0 93,404,872.21 31,936,150 61,468,722 6,228,381 6.67 9.9
397.12 AMI 15-SQ 0 7,530,512.10 1,631,234 5,899,278 502,392 6.67 11.7 397.20 PORTABLE 10-SQ 0 3,516,923.10 2,199,421 1,317,502 351,560 10.00 3.7
TOTAL COMMUNICATION EQUIPMENT 104,452,307.41 35,766,806 68,685,502 7,082,333 6.78
398.00 MISCELLANEOUS EQUIPMENT 10-SQ 0 707,381.78 402,250 305,132 70,744 10.00 4.3
TOTAL DEPRECIABLE COMMON PLANT 395,947,482.60 116,288,140 292,841,892 27,541,449 6.96
RESERVE ADJUSTMENT FOR AMORTIZATION - ELECTRIC PLANT
391.00 OFFICE FURNITURE AND EQUIPMENT (120)24 **
391.10 OFFICE FURNITURE AND EQUIPMENT - COMPUTER HARDWARE 222,255 (44,451)**
391.12 OFFICE FURNITURE AND EQUIPMENT - COMPUTER HARDWARE (54,649)10,930 **
393.00 STORES EQUIPMENT (33,298)6,660 **
394.00 TOOLS, SHOP AND GARAGE EQUIPMENT (117,000)23,400 **
395.00 LABORATORY EQUIPMENT 286,400 (57,280)**
395.12 LABORATORY EQUIPMENT - AMI 40,100 (8,020)**397.00 COMMUNICATION EQUIPMENT (1,610,000)322,000 **397.50 COMMUNICATION EQUIPMENT - SUB INTEGRATION (284,000)56,800 **
397.60 COMMUNICATION EQUIPMENT - DISTRIBUTION (8,452)1,690 **
398.00 MISCELLANEOUS EQUIPMENT 4,865 (973)**
TOTAL RESERVE FOR AMORTIZATION - ELECTRIC PLANT (1,553,899)310,780
RESERVE ADJUSTMENT FOR AMORTIZATION - GAS PLANT - WASHINGTON AND IDAHO
391.10 OFFICE FURNITURE AND EQUIPMENT - COMPUTER HARDWARE 161,492 (32,298)**393.00 STORES EQUIPMENT (3,250)650 **
394.00 TOOLS, SHOP AND GARAGE EQUIPMENT (67,400)13,480 **
395.00 LABORATORY EQUIPMENT 19,568 (3,914)**
395.12 LABORATORY EQUIPMENT - AMI (320)64 **
397.00 COMMUNICATION EQUIPMENT (98,015)19,603 **
397.12 COMMUNICATION EQUIPMENT - AMI (730)146 **
TOTAL RESERVE FOR AMORTIZATION - GAS PLANT - WASHINGTON AND IDAHO 11,345 (2,269)
RESERVE ADJUSTMENT FOR AMORTIZATION - GAS PLANT - ALLOCATED ALL
391.10 OFFICE FURNITURE AND EQUIPMENT - COMPUTER HARDWARE (23,872)4,774 **
394.00 TOOLS, SHOP AND GARAGE EQUIPMENT 163,400 (32,680)**
395.00 LABORATORY EQUIPMENT 1,450 (290)**
397.00 COMMUNICATION EQUIPMENT (22,870)4,574 **
TOTAL RESERVE FOR AMORTIZATION - GAS PLANT - ALLOCATED ALL 118,108 (23,622)
RESERVE ADJUSTMENT FOR AMORTIZATION - GAS PLANT - OREGON
391.10 OFFICE FURNITURE AND EQUIPMENT - COMPUTER HARDWARE (39)8 **
393.00 STORES EQUIPMENT (2,540)508 **
394.00 TOOLS, SHOP AND GARAGE EQUIPMENT 136,761 (27,352)**
395.00 LABORATORY EQUIPMENT (39)8 **397.00 COMMUNICATION EQUIPMENT 274,597 (54,919)**398.00 MISCELLANEOUS EQUIPMENT (825)165 **
TOTAL RESERVE FOR AMORTIZATION - GAS PLANT - OREGON 407,915 (81,582)
Attachment B - Depreciation Summary Schedule
Page 10 of 12
AVISTA CORPORATION
TABLE 1. SUMMARY OF ESTIMATED SURVIVOR CURVE, NET SALVAGE PERCENT, ORIGINAL COST, BOOK DEPRECIATION RESERVE AND
CALCULATED ANNUAL DEPRECIATION ACCRUALS RELATED TO ELECTRIC, GAS AND COMMON PLANT AS OF DECEMBER 31, 2021

PROBABLE NET ORIGINAL COST BOOK FUTURE CALCULATED COMPOSITE
RETIREMENT SURVIVIOR SALVAGE AS OF DEPRECIATION BOOK ANNUAL ACCRUAL REMAINING DEPRECIABLE GROUP DATE CURVE PERCENT DECEMBER 31, 2021 RESERVE ACCRUALS AMOUNT RATE LIFE(1)(2)(3)(4)(5)(6)(7)(8)(9)=(8)/(5)(10)=(7)/(8)

RESERVE ADJUSTMENT FOR AMORTIZATION - COMMON PLANT
391.00 OFFICE FURNITURE AND EQUIPMENT - OFFICE FURNITURE AND EQUIPMENT 4,290,000 (858,000)**391.10 OFFICE FURNITURE AND EQUIPMENT - COMPUTER HARDWARE 9,461,027 (1,892,205)**391.12 OFFICE FURNITURE AND EQUIPMENT - COMPUTER HARDWARE - AMI (249,166)49,833 **
391.13 OFFICE FURNITURE AND EQUIPMENT - COMPUTER HARDWARE - MDM 346,129 (69,226)**
393.00 STORES EQUIPMENT 134,000 (26,800)**
394.00 TOOLS, SHOP AND GARAGE EQUIPMENT 137,000 (27,400)**
395.00 LABORATORY EQUIPMENT 236,500 (47,300)**
397.00 COMMUNICATION EQUIPMENT (8,500,000)1,700,000 **
397.12 COMMUNICATION EQUIPMENT - AMI (438,789)87,758 **397.20 COMMUNICATION EQUIPMENT - PORTABLE 1,511,650 (302,330)**398.00 MISCELLANEOUS EQUIPMENT 301,442 (60,288)**
TOTAL RESERVE FOR AMORTIZATION - COMMON PLANT 7,229,793 (1,445,958)
TOTAL DEPRECIABLE ELECTRIC, GAS AND COMMON PLANT 6,541,255,908.07 2,297,891,258 5,556,247,428 189,794,456 2.90
AMORTIZABLE AND LAND - ELECTRIC PLANT
302.00 FRANCHISES AND CONSENTS 46,749,053.98 15,137,411
303.00 MISCELLANEOUS INTANGIBLE PLANT 7,494,383.92 2,004,315303.10 MISCELLANEOUS INTANGIBLE PLANT - SOFTWARE - 5 YEAR LIFE 26,547,593.96 12,553,034
303.13 MISCELLANEOUS INTANGIBLE PLANT - SAAS - 5 YEAR LIFE 1,768,920.12 189,115303.35 MISCELLANEOUS INTANGIBLE PLANT - SPOKANE RIVER 4,470,355.82 642,365310.20 LAND 3,430,297.19
317.00 ARO 15,536,252.10 2,787,806330.20 LAND 6,980,599.56
330.21 LAND - CONSERVATION - HABITAT 5,989,376.79
330.22 LAND 1,328,873.64 (79,240)330.25 LAND - CONSERVATION - FISHERIES 4,113,031.49
330.45 LAND 175,981.22
340.20 LAND 905,167.67347.00 ARO 351,681.62 104,106
350.20 RIGHTS OF WAY 7,208,600.59360.11 LAND HELD FOR FUTURE USE 9,544,433.56360.20 LAND 8,945,301.21
360.50 LAND - EASEMENTS 367,850.00370.30 METERS - WASHINGTON STANDARD - RESERVE ADJUSTMENT (20,369,298)389.20 LAND 885,665.10
390.20 STRUCTURES AND IMPROVEMENTS - LEASEHOLD 2,359,388.70 747,563
TOTAL AMORTIZABLE AND LAND - ELECTRIC PLANT 155,152,808.24 13,717,176
AMORTIZABLE AND LAND - GAS PLANT - WASHINGTON AND IDAHO
303.00 MISCELLANEOUS INTANGIBLE PLANT 1,794,111.29 436,894
350.10 LAND 413,240.40
374.20 LAND 88,594.70381.00 METERS - WASHINGTON - RESERVE ADJUSTMENT (4,107,087)
389.20 LAND 3,071,016.65
TOTAL AMORTIZABLE AND LAND - GAS PLANT - WASHINGTON AND IDAHO 5,366,963.04 (3,670,193)
AMORTIZABLE AND LAND - GAS PLANT - ALLOCATED ALL
303.10 MISCELLANEOUS INTANGIBLE PLANT - SOFTWARE - 5 YEAR LIFE 450,194.49 177,509
350.10 LAND 899,489.94
TOTAL AMORTIZABLE AND LAND - GAS PLANT - ALLOCATED ALL 1,349,684.43 177,509
AMORTIZABLE AND LAND - GAS PLANT - OREGON
303.00 MISCELLANEOUS INTANGIBLE PLANT 425,950.62 120,960304.00 LAND 59,923.87
350.10 LAND 784.49374.20 LAND 217,817.94389.20 LAND 845,516.91
TOTAL AMORTIZABLE AND LAND - GAS PLANT - OREGON 1,549,993.83 120,960
Attachment B - Depreciation Summary Schedule
Page 11 of 12
AVISTA CORPORATION
TABLE 1. SUMMARY OF ESTIMATED SURVIVOR CURVE, NET SALVAGE PERCENT, ORIGINAL COST, BOOK DEPRECIATION RESERVE AND
CALCULATED ANNUAL DEPRECIATION ACCRUALS RELATED TO ELECTRIC, GAS AND COMMON PLANT AS OF DECEMBER 31, 2021

PROBABLE NET ORIGINAL COST BOOK FUTURE CALCULATED COMPOSITE
RETIREMENT SURVIVIOR SALVAGE AS OF DEPRECIATION BOOK ANNUAL ACCRUAL REMAINING DEPRECIABLE GROUP DATE CURVE PERCENT DECEMBER 31, 2021 RESERVE ACCRUALS AMOUNT RATE LIFE(1)(2)(3)(4)(5)(6)(7)(8)(9)=(8)/(5)(10)=(7)/(8)

AMORTIZABLE AND LAND - COMMON PLANT
303.00 MISCELLANEOUS INTANGIBLE PLANT 6,416,550.79 4,759,832
303.10 MISCELLANEOUS INTANGIBLE PLANT - SOFTWARE - 2 YEAR LIFE 321,950.47 57,006 303.10 MISCELLANEOUS INTANGIBLE PLANT - SOFTWARE - 3 YEAR LIFE 7,429,923.59 576,601 303.10 MISCELLANEOUS INTANGIBLE PLANT - SOFTWARE - 5 YEAR LIFE 174,435,158.14 94,998,734
303.11 MISCELLANEOUS INTANGIBLE PLANT - SOFTWARE - 15 YEAR LIFE (COMPASS)100,831,203.22 47,502,940
303.12 MISCELLANEOUS INTANGIBLE PLANT - SOFTWARE - 12.5 YEAR LIFE (MDM)30,329,509.30 10,189,359
303.13 MISCELLANEOUS INTANGIBLE PLANT - SAAS - 2 YEAR LIFE 67,095.71 18,582
303.13 MISCELLANEOUS INTANGIBLE PLANT - SAAS - 3 YEAR LIFE 595,584.50 56,688
303.13 MISCELLANEOUS INTANGIBLE PLANT - SAAS - 5 YEAR LIFE 6,554,460.92 496,413
389.20 LAND 10,148,559.81
TOTAL AMORTIZABLE AND LAND - COMMON PLANT 337,129,996.45 158,656,155
TOTAL ELECTRIC, GAS AND COMMON PLANT 7,041,805,354.06 2,466,892,865
*LIFE SPAN PROCEDURE WAS USED. CURVE SHOWN IS INTERIM SURVIVOR CURVE.**5-YEAR AMORTIZATION OF RESERVE RELATED TO AMORTIZATION ACCOUNTING.
NOTE: FUTURE ADDITIONS FOR IDAHO AMI METERS WILL USE A RATE OF 7.03% BASED ON A 15-S2.5 SURVIVOR CURVE AND (2) NET SALVAGE PERCENT.
Attachment B - Depreciation Summary Schedule
Page 12 of 12