Employee Benefit Plans

The components of net periodic benefit costs for Registrant’s pension plan, postretirement plan and SERP for the three months ended March 31, 2019 and 2018 were as follows:



	For The Three Months Ended March 31,
	Pension Benefits						Other Postretirement Benefits						SERP
(dollars in thousands)	2019			2018			2019			2018			2019		2018
Components of Net Periodic Benefits Cost:
Service cost	$	1,234		$	1,401		$	53		$	57		$	298	$	274
Interest cost	2,131			1,921			80			72			267		222
Expected return on plan assets	(2,593		)	(2,791		)	(112		)	(123		)	—		—
Amortization of prior service cost (benefit)	109			—			—			—			—		—
Amortization of actuarial (gain) loss	359			345			(150		)	(182		)	118		262
Total expense recognized, before surcharges and allocation to overhead pool	$	1,240		$	876		$	(129	)	$	(176	)	$	683	$	758

Registrant expects to contribute, at least, approximately $3.6 million to its pension plan during 2019.

As authorized by the CPUC in the 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 March 31, 2019, GSWC had a total of $3.1 million over-collection in the two-way pension balancing accounts included as part of the pension regulatory asset (Note 3).