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Property, Plant And Equipment (Tables)

12 Months Ended

Dec. 31, 2021

Property, Plant and Equipment [Abstract]

Net utility property consisted of the following as of December 31 (dollars in thousands):


	2021		2020
Utility plant in service	$	7,166,580	$	6,809,797
Construction work in progress		205,405		175,767
Total		7,371,985		6,985,564
Less: Accumulated depreciation and amortization		2,146,470		1,993,952
Total net utility property	$	5,225,515	$	4,991,612

Summary of Ratio of Depreciation to Average Depreciable Property and Average Service Lives for Utility Plan in Service

For utility operations, the ratio of depreciation provisions to average depreciable property was as follows for the years ended December 31:


	2021			2020			2019
Avista Utilities
Ratio of depreciation to average depreciable property		3.54	%		3.43	%		3.28	%
Alaska Electric Light and Power Company
Ratio of depreciation to average depreciable property		2.77	%		2.77	%		2.48	%

The average service lives for the following broad categories of utility plant in service are (in years):


	Avista Utilities		Alaska Electric Light and Power Company
Electric thermal/other production		26		42
Hydroelectric production		81		42
Electric transmission		50		43
Electric distribution		39		40
Natural gas distribution property		44	N/A
Other shorter-lived general plant		8		18

The gross balances of the major classifications of property, plant and equipment are detailed in the following table as of December 31 (dollars in thousands):


	2021		2020
Avista Utilities:
Electric production	$	1,494,371	$	1,457,497
Electric transmission		945,624		862,987
Electric distribution		2,093,937		1,978,868
Electric construction work-in-progress (CWIP) and other		424,733		384,372
Electric total		4,958,665		4,683,724
Natural gas underground storage		55,684		53,351
Natural gas distribution		1,356,477		1,282,563
Natural gas CWIP and other		87,852		83,644
Natural gas total		1,500,013		1,419,558
Common plant (including CWIP)		740,339		712,609
Total Avista Utilities		7,199,017		6,815,891
AEL&P:
Electric production		106,094		105,076
Electric transmission		22,691		22,419
Electric distribution		27,138		25,814
Electric CWIP and other		7,319		6,677
Electric total		163,242		159,986
Common plant		9,726		9,687
Total AEL&P		172,968		169,673
Total gross utility property		7,371,985		6,985,564
Other (1)		17,818		16,394
Total	$	7,389,803	$	7,001,958

(1)

Included in other property and investments-net and other non-current assets on the Consolidated Balance Sheets. Accumulated depreciation was $2.3 million as of December 31, 2021 and $2.2 million as of December 31, 2020 for the other businesses.