NORTHWEST NATURAL GAS CO

(a) Evaluation of Disclosure Controls and Procedures

NW Holdings and NW Natural management, under the supervision and with the participation of the Chief Executive Officer and Chief Financial Officer, completed an evaluation of the effectiveness of the design and operation of disclosure controls and procedures (as defined in Rules 13a-15(e) and 15d-15(e) of the Securities Exchange Act of 1934, as amended (the Exchange Act)). Based upon this evaluation, the Chief Executive Officer and Chief Financial Officer of each registrant have concluded that, as of the end of the period covered by this report, disclosure controls and procedures were effective to ensure that information required to be disclosed by each such registrant and included in reports filed or submitted under the Exchange Act is recorded, processed, summarized, and reported within the time periods specified in the Securities and Exchange Commission (SEC) rules and forms and that such information is accumulated and communicated to management of each registrant, including the Chief Executive Officer and Chief Financial Officer, as appropriate to allow timely decisions regarding required disclosure.

(b) Changes in Internal Control Over Financial Reporting

NW Holdings and NW Natural management are responsible for establishing and maintaining adequate internal control over financial reporting, as such term is defined in Exchange Act Rule 13a-15(f).

There were no changes in NW Holdings' or NW Natural's internal control over financial reporting during the quarter ended December 31, 2025 that have materially affected, or are reasonably likely to materially affect, internal control over financial reporting for NW Holdings and NW Natural, except as noted below.

Management has excluded SiEnergy Operating, LLC (SiEnergy) from its assessment of internal control over financial reporting as of December 31, 2025 as it was acquired by the Company in a purchase business combination during 2025. Total assets and total net sales of SiEnergy excluded from management's assessment of internal control over financial reporting represent approximately 9.6% and 5.1%, respectively, of the related consolidated financial statement amounts as of and for the year ended December 31, 2025. This exclusion is in accordance with the guidelines established by the Securities and Exchange Commission.

The statements contained in Exhibit 31.1, Exhibit 31.2, Exhibit 31.3, and Exhibit 31.4 should be considered in light of, and read together with, the information set forth in this Item 9A.