James Lynch
Analyst · Janney Montgomery Scott
Thank you, Marty. As Marty mentioned, our first quarter results benefited from the conclusion of our 2021 general rate case. Operating revenue for the quarter increased 106.5% to $270.7 million compared to the prior year first quarter revenue of $131.1 million. The implementation of 2 regulatory mechanisms authorized by the 2021 GRC decision had a significant impact on revenues with the Interim Rate Memorandum Account, or IRMA, adding $80.7 million and the Monterey-Style Water Revenue Mechanism, or M-WRAM, adding $31.7 million. Recorded IRMA and M-WRAM revenue included $70.2 million and $17.6 million, respectively, related to fiscal year 2023. Greg will walk us through the 2021 GRC decision later in the presentation.
The revenue increase also included $13.9 million related to the recognition of Water Revenue Adjustment Mechanism or WRAM revenue that was deferred in previous reporting periods.
First quarter 2024 operating expenses increased $192.9 million compared to the first quarter total operating expenses of $148.6 million. The $44.3 million increase was primarily driven by $9.2 million in higher water production costs associated with the company's new incremental cost balancing account, or ICBA, higher other operations expenses primarily due to $11.4 million in deferred costs associated with the recognized deferred WRAM revenue and a $21.2 million increase in income taxes related to higher pretax earnings.
Net interest expense increased 25.5% to $15 million during the first quarter as compared to $12 million for the first quarter of 2023. The increase was primarily due to higher short-term borrowing rates and higher balances on our outstanding lines of credit. Reported net income for the first quarter was $69.9 million, up nearly 415% compared to a loss of $22.2 million in the first quarter of 2023.
Turning to the earnings per share, first quarter 2024 earnings, diluted earnings per share, was $1.21 compared to first quarter 2023 loss of $0.40 per share. The significant increase in EPS was driven by resolution of our 2021 general rate case, coupled with rate increases and the reversal of previously deferred WRAM revenue. These increases were partially offset by increased expenses, including higher water production expenses related to the new ICBA regulatory mechanism, higher production expenses due to the reversal of WRAM related deferred production costs, and interest expense.
Turning to capital, we continue to make significant investments in our water utilities to help ensure the delivery of safe and reliable water service. We invested just under $110 million in capital improvements during the first quarter of 2024. This was an increase of approximately 34% over the first quarter of 2023. For the year, we anticipate making approximately $380 million in capital investments, which includes an estimated $20 million in developer funded projects.
Depreciation for the first quarter of 2024 was $32.8 million or approximately 30% of first quarter capital investment expenditures. The success of our capital investment strategy is reflected in our rate base growth. Our overall rate base grew to an estimated $2.2 billion by the end of 2023. This was an increase of 15.4% over 2022. Further, based on our current planned capital expenditures and subject to regulatory approval, we estimate the rate base will grow to $2.36 billion by the end of 2024 and $2.47 billion by the end of 2025.
Turning to dividends, at the beginning of the year, we increased the annual dividend 7.7% from $1.04 to $1.12 per share, which marks our 57th consecutive annual dividend increase. And yesterday, we declared a quarterly dividend of $0.28 per share for shareholders on record as of May 6, 2024. This is our 317th consecutive quarterly dividend.
We continue to maintain a strong liquidity position. As of March 31, 2024, the company maintained cash and cash equivalents of $88.3 million, of which $45.4 million was classified as restricted. Further, we had additional short-term borrowing capacity on our lines of credit of $320 million.
Lastly, we are pleased to report that subsequent to the end of the quarter, we received approximately $83 million under the state of California extended arrearage program. The program is designed to provide financial assistance to customers with past due balances that accrued during the COVID-19 pandemic. Marty will provide additional color on the program in a few minutes. With that, I'll turn the call over to Greg to give an update on our 2021 General Rate Case decision. Greg?