| Schedule of Line of Credit Facilities |
The following table summarizes the outstanding revolving credit facilities of the Company and its subsidiaries:
| | | | | | | | | | | | | | | | | | | | | | | | | | | | Company | Debt-to-Total Capitalization Ratio at June 30, 2026 | Provisions for Increased Borrowings, up to a maximum of: | Facility
Limit | Amount Outstanding at June 30, 2026 | Amount Outstanding at June 30, 2025 | Amount Outstanding at December 31, 2025 | Letters of Credit at June 30, 2026 | Expiration
Date | | | | (In millions) | | | | | Montana-Dakota Utilities Co. | 51 | % | $ | 250.0 | | $ | 200.0 | | $ | 82.0 | | $ | 43.3 | | $ | 132.0 | | $ | — | | 12/11/30 | | Cascade Natural Gas Corporation | 49 | % | $ | 225.0 | | $ | 175.0 | | $ | 108.3 | | $ | 14.0 | | $ | 96.5 | | $ | 2.2 | | 12/11/30 | | Intermountain Gas Company | 53 | % | $ | 225.0 | | $ | 175.0 | | $ | 77.9 | | $ | 86.8 | | $ | 67.3 | | $ | — | | 12/11/30 | | MDU Resources Group, Inc. | 47 | % | $ | 250.0 | | $ | 200.0 | | $ | 45.0 | | $ | — | | $ | 32.9 | | $ | 1.0 | | 12/11/30 |
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| Schedule of Long-Term Debt Outstanding |
Long-term debt outstanding was as follows: | | | | | | | | | | | | | | | | Weighted Average Interest Rate at June 30, 2026 | June 30, 2026 | June 30, 2025 | December 31, 2025 | | | (In thousands) | | Senior Notes due on dates ranging from July 15, 2026 to June 15, 2062 | 4.83 | % | $ | 2,110,000 | | $ | 1,947,000 | | $ | 2,010,000 | | | Credit agreements due on December 11, 2030 | 5.27 | % | 231,150 | | 100,800 | | 196,700 | | | Term Loan Agreements due on dates ranging from January 31, 2027 to March 31, 2039 | 4.04 | % | 126,900 | | 61,600 | | 310,900 | | | Commercial paper supported by revolving credit agreement | 4.06 | % | 82,000 | | 43,300 | | 132,000 | | | Medium-Term Notes due on dates ranging from September 15, 2027 to March 16, 2029 | 7.32 | % | 35,000 | | 35,000 | | 35,000 | | | Other notes due on November 30, 2038 | 6.00 | % | 321 | | 338 | | 329 | | | Less unamortized debt issuance costs | | 8,214 | | 6,103 | | 8,074 | | | | | | | | Total long-term debt | | 2,577,157 | | 2,181,935 | | 2,676,855 | | | Less current maturities | | 4,700 | | 136,700 | | 144,700 | | | Net long-term debt | | $ | 2,572,457 | | $ | 2,045,235 | | $ | 2,532,155 | |
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