20230829Attachment A - 2021 - Depreciation Summary Schedule Total.pdf

Net Composite Net Composite
Survivor Salvage Study Remaining Survivor Salvage Study Remaining
DEPRECIABLE GROUP Curve %Rate Life Curve %Rate Life
(1)(2)(3)(4)(5)(2)(3)(4)(5)
ELECTRIC PLANT
STEAM PRODUCTION PLANT
310.30 REMOVING OTHER PROPERTY
KETTLE FALLS SQUARE 0 0.53 17.0 SQUARE 0 0.53 17.0
310.40 EASEMENTS, PERMITS
KETTLE FALLS SQUARE 0 5.60 17.0 SQUARE 0 5.60 17.0
311.00 STRUCTURES AND IMPROVEMENTS
KETTLE FALLS 75-S1.5 (5)1.38 16.4 75-S1.5 (5)1.38 16.4
COLSTRIP 3 AND COMMON - IDAHO 75-S1.5 (3)3.12 5.9 75-S1.5 (3)3.12 5.9
COLSTRIP 3 AND COMMON - WASHINGTON 75-S1.5 (3)3.81 4.0 75-S1.5 (3)3.81 4.0
COLSTRIP 4 - IDAHO 75-S1.5 (4)2.75 5.9 75-S1.5 (4)2.75 5.9
COLSTRIP 4 - WASHINGTON 75-S1.5 (4)4.14 4.0 75-S1.5 (4)4.14 4.0
311.10 STRUCTURES AND IMPROVEMENTS - LANDFILL
KETTLE FALLS 55-S3 0 1.05 15.9 55-S3 0 1.05 15.9
312.00 BOILER PLANT EQUIPMENT
KETTLE FALLS 55-R1 (5)2.62 15.6 55-R1 (5)2.62 15.6
COLSTRIP 3 AND COMMON - IDAHO 55-R1 (3)3.77 5.8 55-R1 (3)3.77 5.8
COLSTRIP 3 AND COMMON - WASHINGTON 55-R1 (3)4.26 3.9 55-R1 (3)4.26 3.9
COLSTRIP 4 - IDAHO 55-R1 (4)5.15 5.9 55-R1 (4)5.15 5.9
COLSTRIP 4 - WASHINGTON 55-R1 (4)7.25 3.9 55-R1 (4)7.25 3.9
313.00 ENGINES AND ENGINE-DRIVEN GENERATORS
COLSTRIP 3 AND COMMON - IDAHO 50-R2.5 (3)16.04 6.0 50-R2.5 (3)16.04 6.0
COLSTRIP 3 AND COMMON - WASHINGTON 50-R2.5 (3)23.02 4.0 50-R2.5 (3)23.02 4.0
COLSTRIP 4 - IDAHO 50-R2.5 (4)5.91 6.0 50-R2.5 (4)5.91 6.0
COLSTRIP 4 - WASHINGTON 50-R2.5 (4)- - 50-R2.5 (4)- -
314.00 TURBOGENERATORS
KETTLE FALLS 37-R0.5 (5)2.79 14.2 37-R0.5 (5)2.79 14.2
COLSTRIP 3 AND COMMON - IDAHO 37-R0.5 (3)4.29 5.7 37-R0.5 (3)4.29 5.7
COLSTRIP 3 AND COMMON - WASHINGTON 37-R0.5 (3)7.42 3.8 37-R0.5 (3)7.42 3.8
COLSTRIP 4 - IDAHO 37-R0.5 (4)7.49 5.7 37-R0.5 (4)7.49 5.7
COLSTRIP 4 - WASHINGTON 37-R0.5 (4)11.48 3.9 37-R0.5 (4)11.48 3.9
315.00 ACCESSORY ELECTRIC EQUIPMENT
KETTLE FALLS 50-S1 (5)3.13 15.3 50-S1 (5)3.13 15.3
COLSTRIP 3 AND COMMON - IDAHO 50-S1 (3)4.42 5.8 50-S1 (3)4.42 5.8
COLSTRIP 3 AND COMMON - WASHINGTON 50-S1 (3)6.15 3.9 50-S1 (3)6.15 3.9
COLSTRIP 4 - IDAHO 50-S1 (4)4.88 5.8 50-S1 (4)4.88 5.8
COLSTRIP 4 - WASHINGTON 50-S1 (4)6.74 3.9 50-S1 (4)6.74 3.9
316.00 MISCELLANEOUS POWER PLANT EQUIPMENT
KETTLE FALLS 60-R2 (5)1.52 15.5 60-R2 (5)1.52 15.5
COLSTRIP 3 AND COMMON - IDAHO 60-R2 (3)2.67 5.9 60-R2 (3)2.67 5.9
COLSTRIP 3 AND COMMON - WASHINGTON 60-R2 (3)4.47 4.0 60-R2 (3)4.47 4.0
COLSTRIP 4 - IDAHO 60-R2 (4)2.88 5.9 60-R2 (4)2.88 5.9
COLSTRIP 4 - WASHINGTON 60-R2 (4)4.87 3.9 60-R2 (4)4.87 3.9
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
Filed Study Rate Settlement Rate
ATTACHMENT A
Page 1 of 11
Net Composite Net Composite
Survivor Salvage Study Remaining Survivor Salvage Study Remaining
DEPRECIABLE GROUP Curve %Rate Life Curve %Rate Life
(1)(2)(3)(4)(5)(2)(3)(4)(5)
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
Filed Study Rate Settlement Rate
HYDRO PRODUCTION PLANT
330.10 ASSET AGREEMENT - SETTLEMENT
LITTLE FALLS 50-SQ 0 1.99 25.1 50-SQ 0 1.99 25.1
330.30 REMOVING PROPERTY OF OTHERS
LITTLE FALLS 100-R4 0 1.25 17.4 100-R4 0 1.25 17.4
LONG LAKE 100-R4 0 1.34 26.8 100-R4 0 1.34 26.8
SPOKANE UPPER FALLS 100-R4 0 0.85 16.0 100-R4 0 0.85 16.0
NINE MILE 100-R4 0 0.58 37.8 100-R4 0 0.58 37.8
POST FALLS 100-R4 0 1.38 19.7 100-R4 0 1.38 19.7
CABINET GORGE 100-R4 0 1.85 34.0 100-R4 0 1.85 34.0
NOXON RAPIDS 100-R4 0 1.74 39.2 100-R4 0 1.74 39.2
330.31 TWIN CREEK CHANNEL RESTORATION
CABINET GORGE 100-R4 0 1.50 50.1 100-R4 0 1.50 50.1
330.40 LAND EASEMENTS
LITTLE FALLS 90-R4 0 - - 90-R4 0 - -
LONG LAKE 90-R4 0 0.12 22.4 90-R4 0 0.12 22.4
NINE MILE 90-R4 0 - - 90-R4 0 - -
POST FALLS 90-R4 0 1.04 36.3 90-R4 0 1.04 36.3
CABINET GORGE 90-R4 0 2.07 26.6 90-R4 0 2.07 26.6
NOXON RAPIDS 90-R4 0 1.55 54.2 90-R4 0 1.55 54.2
330.41 LAND EASEMENTS - CONSERVATION - HABITAT
CABINET GORGE 90-R4 0 1.77 50.3 90-R4 0 1.77 50.3
NOXON RAPIDS 90-R4 0 1.41 55.5 90-R4 0 1.41 55.5
331.00 STRUCTURES AND IMPROVEMENTS
MONROE STREET 110-R1.5 (7)1.83 46.4 110-R1.5 (7)1.83 46.4
LITTLE FALLS 110-R1.5 (5)2.32 36.3 110-R1.5 (5)2.32 36.3
LONG LAKE 110-R1.5 (6)2.69 32.3 110-R1.5 (6)2.69 32.3
SPOKANE UPPER FALLS 110-R1.5 (6)1.57 36.9 110-R1.5 (6)1.57 36.9
NINE MILE 110-R1.5 (4)2.51 37.1 110-R1.5 (4)2.51 37.1
POST FALLS 110-R1.5 (4)2.43 37.3 110-R1.5 (4)2.43 37.3
CABINET GORGE 110-R1.5 (13)1.91 46.5 110-R1.5 (13)1.91 46.5
NOXON RAPIDS 110-R1.5 (21)1.82 51.4 110-R1.5 (21)1.82 51.4
331.10 STRUCTURES AND IMPROVEMENTS - FISH AND WILDLIFE CONSERVATION
LONG LAKE 55-S2.5 (6)0.31 26.6 55-S2.5 (6)0.31 26.6
POST FALLS 55-S2.5 (4)1.63 37.2 55-S2.5 (4)1.63 37.2
CABINET GORGE 55-S2.5 (13)1.95 39.2 55-S2.5 (13)1.95 39.2
NOXON RAPIDS 55-S2.5 (21)2.46 44.8 55-S2.5 (21)2.46 44.8
331.20 STRUCTURES AND IMPROVEMENTS - RECREATION
MONROE STREET 50-R2.5 (7)2.38 38.0 50-R2.5 (7)2.38 38.0
LONG LAKE 50-R2.5 (6)2.69 30.8 50-R2.5 (6)2.69 30.8
SPOKANE UPPER FALLS 50-R2.5 (6)- - 50-R2.5 (6)- -
NINE MILE 50-R2.5 (4)2.34 34.8 50-R2.5 (4)2.34 34.8
POST FALLS 50-R2.5 (4)2.59 34.1 50-R2.5 (4)2.59 34.1
CABINET GORGE 50-R2.5 (13)2.29 40.2 50-R2.5 (13)2.29 40.2
NOXON RAPIDS 50-R2.5 (21)2.46 40.5 50-R2.5 (21)2.46 40.5
331.26 STRUCTURES AND IMPROVEMENTS - RECREATION INFORMATION AND EDUCATION
CABINET GORGE 50-R3 (13)1.69 38.6 50-R3 (13)1.69 38.6
NOXON RAPIDS 50-R3 (21)2.12 35.9 50-R3 (21)2.12 35.9
ATTACHMENT A
Page 2 of 11

Net Composite Net Composite
Survivor Salvage Study Remaining Survivor Salvage Study Remaining
DEPRECIABLE GROUP Curve %Rate Life Curve %Rate Life
(1)(2)(3)(4)(5)(2)(3)(4)(5)
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
Filed Study Rate Settlement Rate
332.00 RESERVOIRS, DAMS AND WATERWAYS
MONROE STREET 110-R1 (7)1.90 45.6 110-R1 (7)1.90 45.6
LITTLE FALLS 110-R1 (5)1.49 35.6 110-R1 (5)1.49 35.6
LONG LAKE 110-R1 (6)1.95 32.2 110-R1 (6)1.95 32.2
SPOKANE UPPER FALLS 110-R1 (6)1.78 36.3 110-R1 (6)1.78 36.3
NINE MILE 110-R1 (4)2.88 36.5 110-R1 (4)2.88 36.5
POST FALLS 110-R1 (4)2.33 36.6 110-R1 (4)2.33 36.6
CABINET GORGE 110-R1 (13)1.71 44.2 110-R1 (13)1.71 44.2
NOXON RAPIDS 110-R1 (21)1.70 47.6 110-R1 (21)1.70 47.6
332.10 RESERVOIRS, DAMS AND WATERWAYS - FISH AND WILDLIFE CONSERVATION
LONG LAKE 65-S1.5 (6)2.89 32.5 65-S1.5 (6)2.89 32.5
NINE MILE 65-S1.5 (4)2.54 36.7 65-S1.5 (4)2.54 36.7
POST FALLS 65-S1.5 (4)2.52 36.6 65-S1.5 (4)2.52 36.6
CABINET GORGE 65-S1.5 (13)2.05 41.8 65-S1.5 (13)2.05 41.8
NOXON RAPIDS 65-S1.5 (21)1.99 44.3 65-S1.5 (21)1.99 44.3
332.15 RESERVOIRS, DAMS AND WATERWAYS - FISH AND WILDLIFE CONSERVATION
NINE MILE 65-S1.5 (4)2.53 36.5 65-S1.5 (4)2.53 36.5
CABINET GORGE 65-S1.5 (13)2.14 42.5 65-S1.5 (13)2.14 42.5
NOXON RAPIDS 65-S1.5 (21)1.88 46.3 65-S1.5 (21)1.88 46.3
332.20 RESERVOIRS, DAMS AND WATERWAYS - RECREATION
LITTLE FALLS 65-S1.5 (5)1.16 29.4 65-S1.5 (5)1.16 29.4
LONG LAKE 65-S1.5 (6)0.33 27.7 65-S1.5 (6)0.33 27.7
NINE MILE 65-S1.5 (4)3.40 30.2 65-S1.5 (4)3.40 30.2
POST FALLS 65-S1.5 (4)2.94 31.5 65-S1.5 (4)2.94 31.5
CABINET GORGE 65-S1.5 (13)1.56 33.9 65-S1.5 (13)1.56 33.9
NOXON RAPIDS 65-S1.5 (21)2.29 36.2 65-S1.5 (21)2.29 36.2
333.00 TURBINES AND GENERATORS
MONROE STREET 70-S0 (7)2.13 38.1 70-S0 (7)2.13 38.1
LITTLE FALLS 70-S0 (5)2.54 34.2 70-S0 (5)2.54 34.2
LONG LAKE 70-S0 (6)0.26 29.0 70-S0 (6)0.26 29.0
SPOKANE UPPER FALLS 70-S0 (6)0.10 35.0 70-S0 (6)0.10 35.0
NINE MILE 70-S0 (4)3.17 34.5 70-S0 (4)3.17 34.5
POST FALLS 70-S0 (4)0.11 32.1 70-S0 (4)0.11 32.1
CABINET GORGE 70-S0 (13)2.34 39.5 70-S0 (13)2.34 39.5
NOXON RAPIDS 70-S0 (21)2.20 42.9 70-S0 (21)2.20 42.9
334.00 ACCESSORY ELECTRIC EQUIPMENT
MONROE STREET 40-S0.5 (7)3.74 26.6 40-S0.5 (7)3.74 26.6
LITTLE FALLS 40-S0.5 (5)2.99 28.6 40-S0.5 (5)2.99 28.6
LONG LAKE 40-S0.5 (6)1.60 27.2 40-S0.5 (6)1.60 27.2
SPOKANE UPPER FALLS 40-S0.5 (6)2.98 26.1 40-S0.5 (6)2.98 26.1
NINE MILE 40-S0.5 (4)3.31 28.4 40-S0.5 (4)3.31 28.4
POST FALLS 40-S0.5 (4)2.52 28.7 40-S0.5 (4)2.52 28.7
CABINET GORGE 40-S0.5 (13)2.71 33.1 40-S0.5 (13)2.71 33.1
NOXON RAPIDS 40-S0.5 (21)3.55 29.0 40-S0.5 (21)3.55 29.0
335.00 MISCELLANEOUS POWER PLANT EQUIPMENT
MONROE STREET 65-R1 (7)2.16 38.9 65-R1 (7)2.16 38.9
LITTLE FALLS 65-R1 (5)2.40 33.5 65-R1 (5)2.40 33.5
LONG LAKE 65-R1 (6)2.20 30.1 65-R1 (6)2.20 30.1
SPOKANE UPPER FALLS 65-R1 (6)2.03 32.1 65-R1 (6)2.03 32.1
NINE MILE 65-R1 (4)2.86 33.8 65-R1 (4)2.86 33.8
POST FALLS 65-R1 (4)2.54 34.2 65-R1 (4)2.54 34.2
CABINET GORGE 65-R1 (13)1.60 42.1 65-R1 (13)1.60 42.1
NOXON RAPIDS 65-R1 (21)1.75 42.4 65-R1 (21)1.75 42.4
335.10 MISCELLANEOUS POWER PLANT EQUIPMENT - FISH AND WILDLIFE CONSERVATION
CABINET GORGE 55-R3 (13)1.20 38.2 55-R3 (13)1.20 38.2
NOXON RAPIDS 55-R3 (21)1.16 34.9 55-R3 (21)1.16 34.9
335.15 MISCELLANEOUS POWER PLANT EQUIPMENT - FISH AND WILDLIFE CONSERVATION
LONG LAKE 55-R3 (6)3.12 32.9 55-R3 (6)3.12 32.9
POST FALLS 55-R3 (4)2.74 37.2 55-R3 (4)2.74 37.2
CABINET GORGE 55-R3 (13)2.37 45.4 55-R3 (13)2.37 45.4
NOXON RAPIDS 55-R3 (21)2.46 47.6 55-R3 (21)2.46 47.6
ATTACHMENT A
Page 3 of 11

Net Composite Net Composite
Survivor Salvage Study Remaining Survivor Salvage Study Remaining
DEPRECIABLE GROUP Curve %Rate Life Curve %Rate Life
(1)(2)(3)(4)(5)(2)(3)(4)(5)
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
Filed Study Rate Settlement Rate
335.20 MISCELLANEOUS POWER PLANT EQUIPMENT - RECREATION
LONG LAKE 55-R3 (6)3.18 33.0 55-R3 (6)3.18 33.0
NINE MILE 55-R3 (4)2.74 36.1 55-R3 (4)2.74 36.1
CABINET GORGE 55-R3 (13)1.44 43.9 55-R3 (13)1.44 43.9
NOXON RAPIDS 55-R3 (21)2.38 44.2 55-R3 (21)2.38 44.2
336.00 ROADS, RAILROADS AND BRIDGES
MONROE STREET 60-S2.5 (7)2.51 30.9 60-S2.5 (7)2.51 30.9
SPOKANE UPPER FALLS 60-S2.5 (6)2.48 36.8 60-S2.5 (6)2.48 36.8
NINE MILE 60-S2.5 (4)2.35 29.4 60-S2.5 (4)2.35 29.4
POST FALLS 60-S2.5 (4)2.52 37.6 60-S2.5 (4)2.52 37.6
CABINET GORGE 60-S2.5 (13)1.27 35.8 60-S2.5 (13)1.27 35.8
NOXON RAPIDS 60-S2.5 (21)2.25 29.9 60-S2.5 (21)2.25 29.9
OTHER PRODUCTION PLANT
341.00 STRUCTURES AND IMPROVEMENTS
KETTLE FALLS 55-R4 (1)3.81 16.9 55-R4 (1)3.81 16.9
NORTHEAST TURBINE 55-R4 (7)0.23 14.0 55-R4 (7)0.23 14.0
BOULDER PARK 55-R4 (1)2.63 20.6 55-R4 (1)2.63 20.6
RATHDRUM TURBINE 55-R4 (4)3.92 12.9 55-R4 (4)3.92 12.9
COYOTE SPRINGS 2 55-R4 (3)2.52 21.4 55-R4 (3)2.52 21.4
342.00 FUEL HOLDERS, PRODUCERS AND ACCESSORIES
KETTLE FALLS 55-R3 (1)1.35 16.3 55-R3 (1)1.35 16.3
NORTHEAST TURBINE 55-R3 (7)0.58 13.9 55-R3 (7)0.58 13.9
BOULDER PARK 55-R3 (1)4.42 20.6 55-R3 (1)4.42 20.6
RATHDRUM TURBINE 55-R3 (4)3.52 12.7 55-R3 (4)3.52 12.7
LANCASTER 55-R3 (3)2.88 18.5 55-R3 (3)2.88 18.5
COYOTE SPRINGS 2 55-R3 (3)2.36 20.8 55-R3 (3)2.36 20.8
343.00 PRIME MOVERS
KETTLE FALLS 60-S2 (1)1.63 16.3 60-S2 (1)1.63 16.3
NORTHEAST TURBINE 60-S2 (7)0.31 13.6 60-S2 (7)0.31 13.6
BOULDER PARK 60-S2 (1)2.35 20.1 60-S2 (1)2.35 20.1
RATHDRUM TURBINE 60-S2 (4)1.74 12.7 60-S2 (4)1.74 12.7
344.00 GENERATORS
KETTLE FALLS 50-R1 (1)4.71 16.1 50-R1 (1)4.71 16.1
NORTHEAST TURBINE 50-R1 (7)0.96 13.2 50-R1 (7)0.96 13.2
BOULDER PARK 50-R1 (1)2.25 18.7 50-R1 (1)2.25 18.7
RATHDRUM TURBINE 50-R1 (4)3.86 12.3 50-R1 (4)3.86 12.3
LANCASTER 50-R1 (3)3.17 17.5 50-R1 (3)3.17 17.5
COYOTE SPRINGS 2 50-R1 (3)3.40 19.9 50-R1 (3)3.40 19.9
344.01 GENERATORS - SOLAR
CENTRAL OPERATIONS FACILITY 25-S2.5 (3)7.11 7.7 25-S2.5 (3)7.11 7.7
BOULDER PARK 25-S2.5 (1)5.34 17.4 25-S2.5 (1)5.34 17.4
345.00 ACCESSORY ELECTRIC EQUIPMENT
KETTLE FALLS 30-S0.5 (1)6.23 15.8 30-S0.5 (1)6.23 15.8
NORTHEAST TURBINE 30-S0.5 (7)0.09 12.3 30-S0.5 (7)0.09 12.3
BOULDER PARK 30-S0.5 (1)4.39 17.4 30-S0.5 (1)4.39 17.4
RATHDRUM TURBINE 30-S0.5 (4)6.61 11.8 30-S0.5 (4)6.61 11.8
LANCASTER 30-S0.5 (3)5.55 17.2 30-S0.5 (3)5.55 17.2
COYOTE SPRINGS 2 30-S0.5 (3)2.46 16.2 30-S0.5 (3)2.46 16.2
ATTACHMENT A
Page 4 of 11

Net Composite Net Composite
Survivor Salvage Study Remaining Survivor Salvage Study Remaining
DEPRECIABLE GROUP Curve %Rate Life Curve %Rate Life
(1)(2)(3)(4)(5)(2)(3)(4)(5)
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
Filed Study Rate Settlement Rate
345.01 ACCESSORY ELECTRIC EQUIPMENT - SOLAR
CENTRAL OPERATIONS FACILITY 25-S2.5 (3)8.92 7.6 25-S2.5 (3)8.92 7.6
346.00 MISCELLANEOUS POWER PLANT EQUIPMENT
NORTHEAST TURBINE 35-R2 (7)0.20 13.1 35-R2 (7)0.20 13.1
BOULDER PARK 35-R2 (1)4.52 19.4 35-R2 (1)4.52 19.4
RATHDRUM TURBINE 35-R2 (4)5.96 12.4 35-R2 (4)5.96 12.4
COYOTE SPRINGS 2 35-R2 (3)4.39 17.6 35-R2 (3)4.39 17.6
TRANSMISSION PLANT
350.30 REMOVING PROPERTY OF OTHERS 80-R4 0 1.04 43.8 80-R4 0 1.04 43.8
350.40 LAND RIGHTS 80-R4 0 1.18 60.4 80-R4 0 1.18 60.4
352.00 STRUCTURES AND IMPROVEMENTS 65-S2 (15)1.76 51.0 65-S2 (15)1.76 51.0
353.00 STATION EQUIPMENT 46-R2 (10)2.34 35.6 46-R2 (10)2.34 35.6
354.00 TOWERS AND FIXTURES 80-R4 (10)1.09 42.8 80-R4 (10)1.09 42.8
355.00 POLES AND FIXTURES 60-R2.5 (40)2.40 48.6 60-R2.5 (40)2.40 48.6
356.00 OVERHEAD CONDUCTORS AND DEVICES 60-R3 (30)2.53 39.8 60-R3 (30)2.53 39.8
357.00 UNDERGROUND CONDUIT 60-R4 0 1.63 45.3 60-R4 0 1.63 45.3
358.00 UNDERGROUND CONDUCTORS AND DEVICES 50-S3 0 2.08 42.2 50-S3 0 2.08 42.2
359.00 ROADS AND TRAILS 75-R4 0 1.23 49.9 75-R4 0 1.23 49.9
DISTRIBUTION PLANT
ID S - Idaho Settlement
360.40 LAND - EASEMENTS 75-R4 0 1.34 67.3 75-R4 0 1.34 67.3
361.00 STRUCTURES AND IMPROVEMENTS 63-S1 (15)1.72 50.2 63-S1 (15)1.72 50.2
362.00 STATION EQUIPMENT ((1) ID Settlement)43-R1.5 (10)2.58 31.5 44-R1.5 (5)2.32 32.9 ID S
364.00 POLES, TOWERS AND FIXTURES 63-R3 (60)2.69 49.1 63-R3 (50)2.48 49.4 ID S
365.00 OVERHEAD CONDUCTORS AND DEVICES 65-R3 (55)2.46 50.2 65-R3 (55)2.46 50.2 ID S
366.00 UNDERGROUND CONDUIT 65-S2.5 (25)1.82 51.8 70-S2 (25)1.65 57.1 ID S
367.00 UNDERGROUND CONDUCTORS AND DEVICES 40-S1.5 (25)2.43 30.6 2.43
368.00 LINE TRANSFORMERS 50-R2.5 (10)2.03 36.7 50-R2.5 (5)1.86 37.2 ID S(1) 362.00 Station Equipment - change to 362.00 EDID only. No change to EDAN. ID Allocated EDAN 362.00 excluded.
SERVICES
369.10 OVERHEAD 70-R4 (35)1.66 50.8 70-R2.5 (5)0.96 56.4 ID S
369.20 UNDERGROUND - SPOKANE NETWORK 70-R4 (35)1.87 61.8 75-R3 (5)1.26 68.1 ID S
369.30 UNDERGROUND - OTHER 70-R4 (35)1.76 55.5 75-R3 (5)1.05 63.4 ID S
METERS
370.10 IDAHO 33-L1.5 (2)5.57 6.5 33-L1.5 (2)5.57 6.5
370.30 WASHINGTON STANDARD 12-L2.5 (2)7.86 9.3 12-L2.5 (2)7.86 9.3
370.40 WASHINGTON AMI 15-S2.5 (2)7.53 11.6 15-S2.5 (2)7.53 11.6
371.00 INSTALLATIONS ON CUSTOMERS' PREMISES - CATALYST BUILDING35-R3 0 2.86 33.6 35-R3 0 2.86 33.6
ELECTRIC VEHICLE CHARGING STATION
371.01 RESIDENTIAL 10-S3 0 10.87 6.6 10-S3 0 10.87 6.6
371.02 MULTI-UNIT DWELLINGS 10-S3 0 7.63 4.7 10-S3 0 7.63 4.7
STREET LIGHTING AND SIGNAL SYSTEMS
373.10 MERCURY VAPOR 33-S1 (15)0.78 16.1 34-S1 (5)0.13 20.7 ID S
373.20 UNDERGROUND CONDUCTOR 33-S1 (15)2.70 24.8 34-S1 (5)2.11 26.9 ID S
373.30 DECORATIVE AND METAL STANDARDS 33-S1 (15)3.10 24.8 34-S1 (5)2.51 26.6 ID S
373.40 HIGH PRESSURE SODIUM VAPOR 33-S1 (15)3.75 25.0 34-S1 (5)3.20 26.1 ID S
373.50 LED 33-S1 (15)3.26 28.8 34-S1 (5)2.81 29.8 ID S
ATTACHMENT A
Page 5 of 11

Net Composite Net Composite
Survivor Salvage Study Remaining Survivor Salvage Study Remaining
DEPRECIABLE GROUP Curve %Rate Life Curve %Rate Life
(1)(2)(3)(4)(5)(2)(3)(4)(5)
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
Filed Study Rate Settlement Rate
GENERAL PLANT
390.10 STRUCTURES AND IMPROVEMENTS - COMPANY 50-S1 (5)2.06 44.5 50-S1 (5)2.06 44.5
OFFICE FURNITURE AND EQUIPMENT
391.00 FURNITURE AND EQUIPMENT 15-SQ 0 6.67 14.0 15-SQ 0 6.67 14.0
391.10 COMPUTER HARDWARE 5-SQ 0 20.00 3.1 5-SQ 0 20.00 3.1
391.12 COMPUTER HARDWARE - AMI 5-SQ 0 20.00 2.5 5-SQ 0 20.00 2.5
TRANSPORTATION EQUIPMENT
392.20 LIGHT TRUCKS 14-L2.5 10 4.17 9.1 14-L2.5 10 4.17 9.1
392.30 MEDIUM TRUCKS 17-L2.5 10 3.81 12.5 17-L2.5 10 3.81 12.5
392.40 HEAVY TRUCKS 20-R4 10 3.94 14.2 20-R4 10 3.94 14.2
392.50 OTHER 16-L2 10 4.73 10.6 16-L2 10 4.73 10.6
393.00 STORES EQUIPMENT 25-SQ 0 4.00 14.2 25-SQ 0 4.00 14.2
TOOLS, SHOP AND GARAGE EQUIPMENT
394.00 TOOLS, SHOP AND GARAGE EQUIPMENT 20-SQ 0 5.00 14.2 20-SQ 0 5.00 14.2
394.10 ELECTRIC VEHICLE CHARGER 10-S2.5 0 9.51 5.0 10-S2.5 0 9.51 5.0
LABORATORY EQUIPMENT
395.00 LABORATORY EQUIPMENT 15-SQ 0 6.67 12.5 15-SQ 0 6.67 12.5
395.12 LABORATORY EQUIPMENT - AMI 15-SQ 0 6.67 11.5 15-SQ 0 6.67 11.5
POWER OPERATED EQUIPMENT
396.30 MEDIUM TRUCKS 16-L2 0 3.66 7.3 16-L2 0 3.66 7.3
396.40 HEAVY TRUCKS 24-S1 0 1.88 14.1 24-S1 0 1.88 14.1
396.50 OTHER 16-S0 0 4.84 11.0 16-S0 0 4.84 11.0
COMMUNICATION EQUIPMENT
397.00 COMMUNICATION EQUIPMENT 15-SQ 0 6.67 6.9 15-SQ 0 6.67 6.9
397.50 SUB INTEGRATION 15-SQ 0 6.67 12.2 15-SQ 0 6.67 12.2
397.60 DISTRIBUTION 15-SQ 0 6.67 13.9 15-SQ 0 6.67 13.9
398.00 MISCELLANEOUS EQUIPMENT 10-SQ 0 10.00 5.3 10-SQ 0 10.00 5.3
ATTACHMENT A
Page 6 of 11

Net Composite Net Composite
Survivor Salvage Study Remaining Survivor Salvage Study Remaining
DEPRECIABLE GROUP Curve %Rate Life Curve %Rate Life
(1)(2)(3)(4)(5)(2)(3)(4)(5)
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
Filed Study Rate Settlement Rate
GAS PLANT - WASHINGTON AND IDAHO
NATURAL GAS STORAGE AND PROCESSING PLANT
350.20 RIGHTS OF WAY 65-R4 0 1.21 44.5 65-R4 0 1.21 44.5
STRUCTURES AND IMPROVEMENTS
351.10 STRUCTURES AND IMPROVEMENTS 55-R2.5 (5)1.60 45.5 55-R2.5 (5)1.60 45.5
351.20 COMPRESSOR STATION 55-R2.5 (5)1.17 24.1 55-R2.5 (5)1.17 24.1
351.30 MEASURING AND REGULATING STATION 55-R2.5 (5)1.11 24.1 55-R2.5 (5)1.11 24.1
351.40 OFFICE 55-R2.5 (5)1.32 29.4 55-R2.5 (5)1.32 29.4
WELLS
352.00 STORAGE WELLS 60-R4 0 1.47 43.2 60-R4 0 1.47 43.2
352.20 RESERVOIRS 50-R4 0 1.90 26.8 50-R4 0 1.90 26.8
352.30 NON-RECOVERABLE GAS 50-R4 0 0.85 32.3 50-R4 0 0.85 32.3
353.00 LINES 65-R4 0 1.50 45.3 65-R4 0 1.50 45.3
354.00 COMPRESSOR STATION EQUIPMENT 55-R4 0 1.77 40.9 55-R4 0 1.77 40.9
355.00 MEASURING AND REGULATING EQUIPMENT 35-R3 0 1.24 34.1 35-R3 0 1.24 34.1
356.00 PURIFICATION EQUIPMENT 35-S2.5 0 1.58 16.3 35-S2.5 0 1.58 16.3
357.00 OTHER EQUIPMENT 45-R2 0 1.72 34.6 45-R2 0 1.72 34.6
DISTRIBUTION PLANT
374.40 LAND - EASEMENTS 60-R4 0 1.70 54.0 60-R4 0 1.70 54.0
375.00 STRUCTURES AND IMPROVEMENTS 45-R2 0 2.36 34.5 45-R2 0 2.36 34.5
376.00 MAINS ((2) - ID Settlement)55-R3 (20)2.10 42.9 55-R3 (15)1.96 42.9 ID S
378.00 MEASURING AND REGULATING EQUIPMENT - GENERAL 32-R2 (15)4.03 20.4 32-R2 (10)3.77 20.4 ID S
379.00 MEASURING AND REGULATING EQUIPMENT - CITY GATE 37-S0.5 (15)3.16 26.0 37-S0.5 (10)2.96 26.0 ID S
380.00 SERVICES 52-R3 (25)2.21 40.8 52-R3 (20)2.07 40.8 ID S(2) 376.00 Mains - change to 376.00 EDID only. No change to EDAN. ID Allocated EDAN 376.00 excluded.
381.00 METERS
IDAHO 35-R1 (3)2.76 25.2 35-R1 (3)2.76 25.2
WASHINGTON 35-R1 (3)3.10 27.0 35-R1 (3)3.10 27.0
WASHINGTON AMI 15-S2.5 (3)7.47 11.9 15-S2.5 (3)7.47 11.9
385.00 INDUSTRIAL MEASURING AND REGULATING STATION EQUIPMENT65-R2.5 (15)1.45 51.6 65-R2.5 (10)1.35 51.6 ID S
GENERAL PLANT
389.42 LAND EASEMENTS 50-R3 0 2.03 46.1 50-R3 0 2.03 46.1
390.10 STRUCTURES AND IMPROVEMENTS - COMPANY 30-R3 (5)3.54 26.3 30-R3 (5)3.54 26.3
391.10 OFFICE FURNITURE AND EQUIPMENT - COMPUTER HARDWARE5-SQ 0 20.00 2.6 5-SQ 0 20.00 2.6
TRANSPORTATION EQUIPMENT
392.20 LIGHT TRUCKS 14-L2.5 10 2.33 11.1 14-L2.5 10 2.33 11.1
392.30 MEDIUM TRUCKS 17-L2.5 10 2.04 13.5 17-L2.5 10 2.04 13.5
392.40 HEAVY TRUCKS 20-R4 10 2.80 15.1 20-R4 10 2.80 15.1
392.50 OTHER 16-L2 10 4.08 10.9 16-L2 10 4.08 10.9
393.00 STORES EQUIPMENT 25-SQ 0 4.00 20.1 25-SQ 0 4.00 20.1
394.00 TOOLS, SHOP AND GARAGE EQUIPMENT 20-SQ 0 5.00 11.8 20-SQ 0 5.00 11.8
395.00 LABORATORY EQUIPMENT 15-SQ 0 6.67 9.3 15-SQ 0 6.67 9.3
395.12 LABORATORY EQUIPMENT - AMI 15-SQ 0 6.67 11.5 15-SQ 0 6.67 11.5
POWER OPERATED EQUIPMENT
396.40 HEAVY TRUCKS 24-S1 0 0.51 14.8 24-S1 0 0.51 14.8
396.50 OTHER 16-S0 0 2.92 11.4 16-S0 0 2.92 11.4
ATTACHMENT A
Page 7 of 11

Net Composite Net Composite
Survivor Salvage Study Remaining Survivor Salvage Study Remaining
DEPRECIABLE GROUP Curve %Rate Life Curve %Rate Life
(1)(2)(3)(4)(5)(2)(3)(4)(5)
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
Filed Study Rate Settlement Rate
397.00 COMMUNICATION EQUIPMENT
FULLY ACCRUED FULLY ACCRUED - - FULLY ACCRUED - -
AMORTIZED 15-SQ 0 6.67 8.2 15-SQ 0 6.67 8.2
397.12 COMMUNICATION EQUIPMENT - AMI 15-SQ 0 6.67 11.5 15-SQ 0 6.67 11.5
GAS PLANT - ALLOCATED ALL
391.10 OFFICE FURNITURE AND EQUIPMENT - COMPUTER HARDWARE5-SQ 0 20.00 2.1 5-SQ 0 20.00 2.1
TRANSPORTATION EQUIPMENT
392.20 LIGHT TRUCKS 14-L2.5 10 6.29 12.5 14-L2.5 10 6.29 12.5
392.50 OTHER 16-L2 10 5.96 12.6 16-L2 10 5.96 12.6
394.00 TOOLS, SHOP AND GARAGE EQUIPMENT 20-SQ 0 5.00 13.9 20-SQ 0 5.00 13.9
395.00 LABORATORY EQUIPMENT 15-SQ 0 6.67 8.1 15-SQ 0 6.67 8.1
397.00 COMMUNICATION EQUIPMENT 15-SQ 0 6.67 8.5 15-SQ 0 6.67 8.5
GAS PLANT - OREGON
NATURAL GAS STORAGE AND PROCESSING PLANT
350.20 RIGHTS OF WAY 65-R4 0 1.79 53.8 65-R4 0 1.79 53.8
STRUCTURES AND IMPROVEMENTS
351.10 STRUCTURES AND IMPROVEMENTS 55-R2.5 (5)2.21 46.1 55-R2.5 (5)2.21 46.1
351.20 COMPRESSOR STATION 55-R2.5 (5)1.89 43.6 55-R2.5 (5)1.89 43.6
351.40 OFFICE 55-R2.5 (5)1.74 53.0 55-R2.5 (5)1.74 53.0
WELLS
352.00 STORAGE WELLS 60-R4 0 1.73 48.6 65-R2.5 0 1.55 48.6 OR S
352.20 RESERVOIRS 50-R4 0 2.03 39.4 50-R4 0 2.03 39.4
352.30 NON-RECOVERABLE GAS 50-R4 0 1.95 37.6 50-R4 0 1.95 37.6
353.00 LINES 65-R4 0 1.63 54.1 65-R4 0 1.63 54.1
354.00 COMPRESSOR STATION EQUIPMENT 55-R4 0 1.83 42.3 55-R2 0 1.76 42.3 OR S
355.00 MEASURING AND REGULATING EQUIPMENT 35-R3 0 1.09 34.2 35-R3 0 1.09 34.2
356.00 PURIFICATION EQUIPMENT 35-S2.5 0 3.77 25.6 35-S2.5 0 3.77 25.6
357.00 OTHER EQUIPMENT 45-R2 0 2.09 42.1 45-R2 0 2.09 42.1
DISTRIBUTION PLANT
374.40 LAND - EASEMENTS 60-R4 0 1.67 52.6 60-R4 0 1.67 52.6
375.00 STRUCTURES AND IMPROVEMENTS 45-R2 0 2.56 33.3 45-R2 0 2.56 33.3
376.00 MAINS 55-R3 (20)2.11 43.2 57-R3 (17)1.94 43.2 OR S
378.00 MEASURING AND REGULATING EQUIPMENT - GENERAL 32-R2 (15)4.02 22.4 32-R2 (15)4.02 22.4
379.00 MEASURING AND REGULATING EQUIPMENT - CITY GATE 37-S0.5 (15)3.22 30.1 37-S0.5 (15)3.22 30.1
380.00 SERVICES 52-R3 (25)2.15 41.2 54-R3 (23)1.99 41.2 OR S
381.00 METERS 35-R1 (3)3.34 26.0 35-R1 (3)3.34 26.0
385.00 INDUSTRIAL MEASURING AND REGULATING STATION EQUIPMENT65-R2.5 (15)1.44 55.4 65-R2.5 (15)1.44 55.4
387.00 OTHER EQUIPMENT 18-SQ 0 - - 18-SQ 0 - -
OR S - Oregon Settlement
GENERAL PLANT
390.10 STRUCTURES AND IMPROVEMENTS - COMPANY 30-R3 (5)3.37 17.2 30-R3 (5)3.37 17.2
391.10 OFFICE FURNITURE AND EQUIPMENT - COMPUTER HARDWARE5-SQ 0 20.00 2.5 5-SQ 0 20.00 2.5
TRANSPORTATION EQUIPMENT
392.20 LIGHT TRUCKS 14-L2.5 10 5.50 9.3 14-L2.5 10 5.50 9.3
392.30 MEDIUM TRUCKS 17-L2.5 10 2.90 12.3 17-L2.5 10 2.90 12.3
392.50 OTHER 16-L2 10 5.85 12.3 16-L2 10 5.85 12.3
ATTACHMENT A
Page 8 of 11

Net Composite Net Composite
Survivor Salvage Study Remaining Survivor Salvage Study Remaining
DEPRECIABLE GROUP Curve %Rate Life Curve %Rate Life
(1)(2)(3)(4)(5)(2)(3)(4)(5)
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
Filed Study Rate Settlement Rate
393.00 STORES EQUIPMENT 25-SQ 0 4.00 4.6 25-SQ 0 4.00 4.6
394.00 TOOLS, SHOP AND GARAGE EQUIPMENT 20-SQ 0 5.00 9.4 20-SQ 0 5.00 9.4
395.00 LABORATORY EQUIPMENT 15-SQ 0 6.67 12.5 15-SQ 0 6.67 12.5
396.50 POWER OPERATED EQUIPMENT - OTHER 16-S0 0 - - 16-S0 0 - -
397.00 COMMUNICATION EQUIPMENT 15-SQ 0 6.67 6.8 15-SQ 0 6.67 6.8
398.00 MISCELLANEOUS EQUIPMENT
FULLY ACCRUED FULLY ACCRUED - - FULLY ACCRUED - -
AMORTIZED 10-SQ 0 10.00 9.5 10-SQ 0 10.00 9.5
COMMON PLANT
LAND AND LAND RIGHTS
389.30 REMOVING PROPERTY OF OTHERS 65-R4 0 1.67 55.6 65-R4 0 1.67 55.6
389.40 LAND EASEMENTS 65-R4 0 1.26 57.6 65-R4 0 1.26 57.6
390.10 STRUCTURES AND IMPROVEMENTS - COMPANY 50-R2 (10)2.45 41.0 50-R2 (10)2.45 41.0
OFFICE FURNITURE AND EQUIPMENT
391.00 OFFICE FURNITURE AND EQUIPMENT 15-SQ 0 6.67 8.4 15-SQ 0 6.67 8.4
391.10 COMPUTER HARDWARE
FULLY ACCRUED FULLY ACCRUED - - FULLY ACCRUED - -
AMORTIZED 5-SQ 0 20.00 2.4 5-SQ 0 20.00 2.4
391.12 COMPUTER HARDWARE - AMI 5-SQ 0 20.00 1.6 5-SQ 0 20.00 1.6
391.13 COMPUTER HARDWARE - MDM 5-SQ 0 20.00 1.0 5-SQ 0 20.00 1.0
TRANSPORTATION EQUIPMENT
392.10 AUTOS 11-S2.5 10 - - 11-S2.5 10 - -
392.20 LIGHT TRUCKS 14-L2.5 10 1.87 11.2 14-L2.5 10 1.87 11.2
392.30 MEDIUM TRUCKS 17-L2.5 10 1.62 13.9 17-L2.5 10 1.62 13.9
392.40 HEAVY TRUCKS 20-R4 10 6.00 14.0 20-R4 10 6.00 14.0
392.50 OTHER 16-L2 10 2.28 12.8 16-L2 10 2.28 12.8
392.60 AIRPLANE 12-S1.5 30 1.36 8.7 12-S1.5 30 1.36 8.7
393.00 STORES EQUIPMENT 25-SQ 0 4.00 18.1 25-SQ 0 4.00 18.1
394.00 TOOLS, SHOP AND GARAGE EQUIPMENT 20-SQ 0 5.00 12.3 20-SQ 0 5.00 12.3
395.00 LABORATORY EQUIPMENT 15-SQ 0 6.67 10.1 15-SQ 0 6.67 10.1
POWER OPERATED EQUIPMENT
396.30 MEDIUM TRUCKS 16-L2 0 - - 16-L2 0 - -
396.50 OTHER 16-S0 0 3.24 8.9 16-S0 0 3.24 8.9
COMMUNICATION EQUIPMENT
397.00 COMMUNICATION EQUIPMENT 15-SQ 0 6.67 9.9 15-SQ 0 6.67 9.9
397.12 AMI 15-SQ 0 6.67 11.7 15-SQ 0 6.67 11.7
397.20 PORTABLE 10-SQ 0 10.00 3.7 10-SQ 0 10.00 3.7
398.00 MISCELLANEOUS EQUIPMENT 10-SQ 0 10.00 4.3 10-SQ 0 10.00 4.3
TOTAL RESERVE FOR AMORTIZATION - ELECTRIC PLANT (5-Year Amortization as-filed and agreed to in settlement)
RESERVE ADJUSTMENT FOR AMORTIZATION - GAS PLANT - WASHINGTON AND IDAHO
391.10 OFFICE FURNITURE AND EQUIPMENT - COMPUTER HARDWARE
393.00 STORES EQUIPMENT
394.00 TOOLS, SHOP AND GARAGE EQUIPMENT
395.00 LABORATORY EQUIPMENT
395.12 LABORATORY EQUIPMENT - AMI
397.00 COMMUNICATION EQUIPMENT
397.12 COMMUNICATION EQUIPMENT - AMI
TOTAL RESERVE FOR AMORTIZATION - GAS PLANT - WASHINGTON AND IDAHO (5-Year Amortization as-filed and agreed to in settlement)
RESERVE ADJUSTMENT FOR AMORTIZATION - GAS PLANT - ALLOCATED ALL
391.10 OFFICE FURNITURE AND EQUIPMENT - COMPUTER HARDWARE
394.00 TOOLS, SHOP AND GARAGE EQUIPMENT
395.00 LABORATORY EQUIPMENT
397.00 COMMUNICATION EQUIPMENT
TOTAL RESERVE FOR AMORTIZATION - GAS PLANT - ALLOCATED ALL
ATTACHMENT A
Page 9 of 11

Net Composite Net Composite
Survivor Salvage Study Remaining Survivor Salvage Study Remaining
DEPRECIABLE GROUP Curve %Rate Life Curve %Rate Life
(1)(2)(3)(4)(5)(2)(3)(4)(5)
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
Filed Study Rate Settlement Rate
RESERVE ADJUSTMENT FOR AMORTIZATION - GAS PLANT - OREGON
391.10 OFFICE FURNITURE AND EQUIPMENT - COMPUTER HARDWARE
393.00 STORES EQUIPMENT
394.00 TOOLS, SHOP AND GARAGE EQUIPMENT
395.00 LABORATORY EQUIPMENT
397.00 COMMUNICATION EQUIPMENT
398.00 MISCELLANEOUS EQUIPMENT
TOTAL RESERVE FOR AMORTIZATION - GAS PLANT - OREGON (5-Year Amortization as-filed and agreed to in settlement)
RESERVE ADJUSTMENT FOR AMORTIZATION - COMMON PLANT
391.00 OFFICE FURNITURE AND EQUIPMENT - OFFICE FURNITURE AND EQUIPMENT
391.10 OFFICE FURNITURE AND EQUIPMENT - COMPUTER HARDWARE
391.12 OFFICE FURNITURE AND EQUIPMENT - COMPUTER HARDWARE - AMI
391.13 OFFICE FURNITURE AND EQUIPMENT - COMPUTER HARDWARE - MDM
393.00 STORES EQUIPMENT
394.00 TOOLS, SHOP AND GARAGE EQUIPMENT
395.00 LABORATORY EQUIPMENT
397.00 COMMUNICATION EQUIPMENT
397.12 COMMUNICATION EQUIPMENT - AMI
397.20 COMMUNICATION EQUIPMENT - PORTABLE
398.00 MISCELLANEOUS EQUIPMENT
TOTAL RESERVE FOR AMORTIZATION - COMMON PLANT (5-Year Amortization as-filed and agreed to in settlement)
TOTAL DEPRECIABLE ELECTRIC, GAS AND COMMON PLANT
AMORTIZABLE AND LAND - ELECTRIC PLANT
302.00 FRANCHISES AND CONSENTS
303.00 MISCELLANEOUS INTANGIBLE PLANT
303.10 MISCELLANEOUS INTANGIBLE PLANT - SOFTWARE - 5 YEAR LIFE
303.13 MISCELLANEOUS INTANGIBLE PLANT - SAAS - 5 YEAR LIFE
303.35 MISCELLANEOUS INTANGIBLE PLANT - SPOKANE RIVER
310.20 LAND
317.00 ARO
330.20 LAND
330.21 LAND - CONSERVATION - HABITAT
330.22 LAND
330.25 LAND - CONSERVATION - FISHERIES
330.45 LAND
340.20 LAND
347.00 ARO
350.20 RIGHTS OF WAY
360.11 LAND HELD FOR FUTURE USE
360.20 LAND
360.50 LAND - EASEMENTS
370.30 METERS - WASHINGTON STANDARD - RESERVE ADJUSTMENT
389.20 LAND
390.20 STRUCTURES AND IMPROVEMENTS - LEASEHOLD
TOTAL AMORTIZABLE AND LAND - ELECTRIC PLANT
AMORTIZABLE AND LAND - GAS PLANT - WASHINGTON AND IDAHO
303.00 MISCELLANEOUS INTANGIBLE PLANT
350.10 LAND
374.20 LAND
381.00 METERS - WASHINGTON - RESERVE ADJUSTMENT
389.20 LAND
TOTAL AMORTIZABLE AND LAND - GAS PLANT - WASHINGTON AND IDAHO
AMORTIZABLE AND LAND - GAS PLANT - ALLOCATED ALL
303.10 MISCELLANEOUS INTANGIBLE PLANT - SOFTWARE - 5 YEAR LIFE
350.10 LAND
TOTAL AMORTIZABLE AND LAND - GAS PLANT - ALLOCATED ALL
ATTACHMENT A
Page 10 of 11

Net Composite Net Composite
Survivor Salvage Study Remaining Survivor Salvage Study Remaining
DEPRECIABLE GROUP Curve %Rate Life Curve %Rate Life
(1)(2)(3)(4)(5)(2)(3)(4)(5)
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
Filed Study Rate Settlement Rate
AMORTIZABLE AND LAND - GAS PLANT - OREGON
303.00 MISCELLANEOUS INTANGIBLE PLANT
304.00 LAND
350.10 LAND
374.20 LAND
389.20 LAND
TOTAL AMORTIZABLE AND LAND - GAS PLANT - OREGON
AMORTIZABLE AND LAND - COMMON PLANT
303.00 MISCELLANEOUS INTANGIBLE PLANT
303.10 MISCELLANEOUS INTANGIBLE PLANT - SOFTWARE - 2 YEAR LIFE
303.10 MISCELLANEOUS INTANGIBLE PLANT - SOFTWARE - 3 YEAR LIFE
303.10 MISCELLANEOUS INTANGIBLE PLANT - SOFTWARE - 5 YEAR LIFE
303.11 MISCELLANEOUS INTANGIBLE PLANT - SOFTWARE - 15 YEAR LIFE (COMPASS)
303.12 MISCELLANEOUS INTANGIBLE PLANT - SOFTWARE - 12.5 YEAR LIFE (MDM)
303.13 MISCELLANEOUS INTANGIBLE PLANT - SAAS - 2 YEAR LIFE
303.13 MISCELLANEOUS INTANGIBLE PLANT - SAAS - 3 YEAR LIFE
303.13 MISCELLANEOUS INTANGIBLE PLANT - SAAS - 5 YEAR LIFE
389.20 LAND
TOTAL AMORTIZABLE AND LAND - COMMON PLANT
TOTAL ELECTRIC, GAS AND COMMON PLANT
*LIFE SPAN PROCEDURE WAS USED. CURVE SHOWN IS INTERIM SURVIVOR CURVE.
**5-YEAR AMORTIZATION OF RESERVE RELATED TO AMORTIZATION ACCOUNTING.
ATTACHMENT A
Page 11 of 11