Employee Benefit Plans

The components of net periodic benefit costs, before allocation to the overhead pool, for Registrant’s pension plan, postretirement plan and SERP for the three and nine months ended September 30, 2017 and 2016 are as follows:



	For The Three Months Ended September 30,
	Pension Benefits						Other Postretirement Benefits						SERP
(dollars in thousands)	2017			2016			2017			2016			2017		2016
Components of Net Periodic Benefits Cost:
Service cost	$	1,250		$	1,274		$	53		$	68		$	232	$	200
Interest cost	1,976			1,978			73			97			223		186
Expected return on plan assets	(2,428		)	(2,457		)	(107		)	(122		)	—		—
Amortization of prior service cost (benefit)	—			12			—			(9		)	3		6
Amortization of actuarial (gain) loss	231			228			(242		)	(150		)	194		73
Net periodic pension cost under accounting standards	1,029			1,035			(223		)	(116		)	652		465
Regulatory adjustment — deferred	266			221			—			—			—		—
Total expense recognized, before surcharges and allocation to overhead pool	$	1,295		$	1,256		$	(223	)	$	(116	)	$	652	$	465



	For The Nine Months Ended September 30,
	Pension Benefits						Other Postretirement Benefits						SERP
(dollars in thousands)	2017			2016			2017			2016			2017		2016
Components of Net Periodic Benefits Cost:
Service cost	$	3,750		$	3,822		$	171		$	204		$	696	$	600
Interest cost	5,928			5,934			243			291			669		558
Expected return on plan assets	(7,278		)	(7,377		)	(351		)	(366		)	—		—
Amortization of prior service cost (benefit)	—			36			—			(27		)	9		18
Amortization of actuarial (gain) loss	693			684			(582		)	(450		)	582		219
Net periodic pension cost under accounting standards	3,093			3,099			(519		)	(348		)	1,956		1,395
Regulatory adjustment — deferred	791			644			—			—			—		—
Total expense recognized, before surcharges and allocation to overhead pool	$	3,884		$	3,743		$	(519	)	$	(348	)	$	1,956	$	1,395

Registrant contributed $6.5 million to its pension plan during the nine months ended September 30, 2017.

Regulatory Adjustment:

As authorized by the CPUC in the most recent water and electric general rate case decisions, GSWC utilizes two-way balancing accounts for its water and electric regions and the general office to track differences between the forecasted annual pension expenses in rates or expected to be in rates and the actual annual expense recorded by GSWC in accordance with the accounting guidance for pension costs. As of September 30, 2017, GSWC had a total of $1.1 million over-collection in the two-way pension balancing accounts included as part of the pension regulatory asset (Note 2).