Northwest Natural Holding Co — Form 8-K

Northwest Natural Gas Company executed the Twenty-ninth Supplemental Indenture dated August 15, 2026, establishing two new bond series under its 1946 mortgage: (1) 5.62% Series due 2036, maturing September 3, 2036, and (2) 6.26% Series due 2056, maturing September 3, 2056. The indenture was entered with Deutsche Bank Trust Company Americas as trustee. Specific principal amounts for each series are not disclosed in this document; the filing is a form/framework establishing the terms, not a pricing announcement. Both series are fully registered, carry make-whole redemption premiums (calculated via Treasury spread + 0.50%), and secured by the company's Oregon and Washington utility properties under the original 1946 mortgage and prior supplements.