as the Guernsey Power Station reached substantial completion during the period. The $10.6 million increase in contract receivables during the period represented a use of cash, primarily due to GPS and TRC project billings and, as previously mentioned, the reclassification of project retentions related to the Guernsey Power Station. The increase in contract liabilities of $15.0 million represented a source of cash, primarily due to the net effect of the early phase of construction activities on a GPS project and post peak phase of certain APC projects. However, reductions in the combined level of accounts payables and accrued expenses in the amount of $26.9 million and the increase of other assets of $4.1 million, represented uses of cash during the period.
During the three months ended April 30, 2023, our primary source of cash from investing activities was the net maturities of our short-term investments, which consist entirely of CDs issued by the Bank, in the amount of $59.8 million. We used $30.4 million of these proceeds to invest in available-for-sale securities of U.S. Treasury notes. We also used $0.6 million to make capital expenditures.
For the three months ended April 30, 2023, we used $6.5 million cash in financing activities, including $3.7 million used to repurchase shares of common stock and $3.4 million used for the payment of regular cash dividends. We received proceeds from the exercise of stock options in the amount of $0.5 million, which represented a source of cash. As of April 30, 2023, there were no restrictions with respect to intercompany payments between the holding company, GPS, TRC, APC and SMC.
During the three months ended April 30, 2022, our balance of cash and cash equivalents decreased by a net amount of $158.2 million and our working capital decreased by $22.9 million to $261.3 million as of April 30, 2022. The net amount of cash used in operating activities for the three months ended April 30, 2022 was $39.7 million. Our net income for the period, adjusted favorably by the net amount of non-cash income and expense items, represented a source of cash in the total amount of $9.8 million. However, reductions in the balance of contract liabilities and the combined level of accounts payable and accrued expenses in the amounts of $20.9 million and $15.2 million, respectively, represented uses of cash. Both of these reductions related primarily to the decline in the construction activity of the Guernsey Power Station project. Likewise, the increases in the amounts of accounts receivable, contract assets, prepaid expenses and other assets, in the total of $13.3 million, represented uses of cash during the period.
During the three months ended April 30, 2022, we also used cash to increase the level of our short-term investments, which consisted entirely of CDs issued by the Bank, by $85.0 million. We also used $30.7 million cash in financing activities during the three months ended April 30, 2022, including $27.1 million used to repurchase shares of our common stock, and $3.7 million used for the payment of regular cash dividends.
At April 30, 2023, a portion of our balance of cash and cash equivalents was invested in certificates of deposit and money market funds with most of its net assets invested in cash, U.S. Treasury obligations and repurchase agreements secured by U.S. government obligations. The major portion of our domestic operating bank account balances are maintained with the Bank. We do maintain certain Euro-based bank accounts in Ireland and certain pound sterling-based bank accounts in the U.K. in support of the operations of APC.
In order to monitor the actual and necessary levels of liquidity for our business, we focus on net liquidity, or working capital, in addition to our cash balances. During the three months ended April 30, 2023, our net liquidity decreased by $3.6 million to $232.6 million as of April 30, 2023 from $236.2 million as of January 31, 2023, due primarily to common stock repurchases and the payment of cash dividends, partially offset by our net income for the period. As we have no debt service, as our fixed asset acquisitions in a reporting period are typically low, and as our net liquidity includes our short-term investments and available-for-sale U.S. Treasury notes, our levels of working capital are not subjected to the volatility that affects our levels of cash and cash equivalents.
During April 2021, we amended our Credit Agreement with the Bank which extended the expiration date of the Credit Agreement to May 31, 2024 and reduced the borrowing rate. On March 6, 2023, we entered into the Second Amendment to the Credit Agreement. The Second Amendment modified the Credit Agreement to, primarily, replace the interest pricing with a rate of SOFR plus 1.6% and add SOFR successor rate language. The Credit Agreement, as amended, includes the following features, among others: a lending commitment of $50.0 million including a revolving loan and an accordion feature which allows for an additional commitment amount of $10.0 million, subject to certain conditions. Additionally,