Employee Benefit Plans

The components of net periodic benefit costs, before allocation to the overhead pool, for Registrant’s pension plan, postretirement plan and the supplemental executive retirement plan ("SERP") for the three and nine months ended September 30, 2018 and 2017 are as follows:



	For The Three Months Ended September 30,
	Pension Benefits						Other Postretirement Benefits						SERP
(dollars in thousands)	2018			2017			2018			2017			2018		2017
Components of Net Periodic Benefits Cost:
Service cost	$	1,335		$	1,250		$	48		$	53		$	274	$	232
Interest cost	1,912			1,976			75			73			222		223
Expected return on plan assets	(2,793		)	(2,428		)	(123		)	(107		)	—		—
Amortization of prior service cost (benefit)	—			—			—			—			—		3
Amortization of actuarial (gain) loss	314			231			(212		)	(242		)	262		194
Net periodic pension cost under accounting standards	768			1,029			(212		)	(223		)	758		652
Regulatory adjustment — deferred	—			266			—			—			—		—
Total expense recognized, before surcharges and allocation to overhead pool	$	768		$	1,295		$	(212	)	$	(223	)	$	758	$	652



	For The Nine Months Ended September 30,
	Pension Benefits						Other Postretirement Benefits						SERP
(dollars in thousands)	2018			2017			2018			2017			2018		2017
Components of Net Periodic Benefits Cost:
Service cost	$	4,005		$	3,750		$	162		$	171		$	822	$	696
Interest cost	5,736			5,928			219			243			666		669
Expected return on plan assets	(8,379		)	(7,278		)	(369		)	(351		)	—		—
Amortization of prior service cost (benefit)	—			—			—			—			—		9
Amortization of actuarial (gain) loss	942			693			(576		)	(582		)	786		582
Net periodic pension cost under accounting standards	2,304			3,093			(564		)	(519		)	2,274		1,956
Regulatory adjustment — deferred	—			791			—			—			—		—
Total expense recognized, before surcharges and allocation to overhead pool	$	2,304		$	3,884		$	(564	)	$	(519	)	$	2,274	$	1,956

In accordance with new accounting guidance (Note 1), effective January 1, 2018, Registrant changed the financial statement presentation for the costs of its defined benefit pension plans and other retirement benefits. The components of net periodic benefits cost, other than the service cost component, have been included in the line item “Other, net” in Registrant's income statements. Prior period amounts have been reclassified on the income statements to conform to the current-period presentation.

During the nine months ended September 30, 2018, Registrant contributed $6.0 million to its pension plan.

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, 2018, GSWC had a $2.5 million over-collection in the two-way pension balancing accounts included as part of the pension regulatory asset (Note 3).