西北天然气 2025年度报告

Form 11-K (Mark One)[X]ANNUAL REPORT PURSUANT TO SECTION 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 OR []TRANSITION REPORT PURSUANT TO SECTION 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934For the transition period from ___________ to____________ Commission file number 1-38681 A. Full title of the plan and the address of the plan, if different from that of the issuer named below: NORTHWEST NATURAL GAS COMPANYRETIREMENT K SAVINGS PLAN B. Name of issuer of the securities held pursuant to the plan and the address of its principal executive office: NORTHWEST NATURAL HOLDING COMPANY 250 SW Taylor StreetPortland, Oregon 97204 NORTHWEST NATURAL GAS COMPANYRETIREMENT K SAVINGS PLAN TABLE OF CONTENTS Table of Contents REPORT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM Plan Administrator and Plan ParticipantsNorthwest Natural Gas Company Retirement K Savings Plan Opinion on the financial statementsWe have audited the accompanying statements of net assets available for benefits of Northwest Natural Gas Company Retirement K Savings Plan (the “Plan”) as of December31, 2025 and 2024, the related statements of changes in netassets available for benefits for the years then ended, and the related notes (collectively referred to as the “financial Basis for opinionThese financial statements are the responsibility of the Plan’s management. Our responsibility is to express an opinion on the Plan’s financial statements based on our audits. We are a public accounting firm registered with the Public CompanyAccounting Oversight Board (United States) (“PCAOB”) and are required to be independent with respect to the Plan in We conducted our audits in accordance with the standards of the PCAOB. Those standards require that we plan andperform the audit to obtain reasonable assurance about whether the financial statements are free of materialmisstatement, whether due to error or fraud. The Plan is not required to have, nor were we engaged to perform, an auditof its internal control over financial reporting. As part of our audits we are required to obtain an understanding of internal Our audits included performing procedures to assess the risks of material misstatement of the financial statements,whether due to error or fraud, and performing procedures that respond to those risks. Such procedures includedexamining, on a test basis, evidence regarding the amounts and disclosures in the financial statements. Our audits also Supplemental informationThe supplemental schedule of the delinquent participant contributions for the year ended December31, 2025 and schedule of assets (held at end of year) as of December31, 2025 (“supplemental information”) has been subjected toaudit procedures performed in conjunction with the audit of the Plan’s financial statements. The supplemental informationis the responsibility of the Plan’s management. Our audit procedures included determining whether the supplementalinformation reconciles to the financial statements or the underlying accounting and other records, as applicable, and Philadelphia, PennsylvaniaJune25, 2026 NORTHWEST NATURAL GAS COMPANYRETIREMENT K SAVINGS PLAN NORTHWEST NATURAL GAS COMPANYRETIREMENT K SAVINGS PLAN STATEMENTS OF CHANGES IN NET ASSETS AVAILABLE FOR BENEFITS NORTHWEST NATURAL GAS COMPANYRETIREMENT K SAVINGS PLAN NOTES TO FINANCIAL STATEMENTSDecember 31, 2025 and 2024 1. DESCRIPTION OF PLAN The following description of the Northwest Natural Gas Company Retirement K Savings Plan (the Plan) provides onlygeneral information. Employees and Plan participants should refer to the Plan document and summary plan description fora more comprehensive description of the Plan’s provisions. GeneralThe Plan is a defined contribution plan covering substantially all employees of Northwest Natural Gas Company (NW Natural), SiEnergy Holding, LLC (SiEnergy, formerly Si Investment Co, LLC) and NW Natural Renewables Holdings, LLC(collectively, the Company). NW Natural and NW Natural Renewables Holdings, LLC are wholly-owned direct subsidiaries Effective January 7, 2025, Si Investment Co, LLC was added as an adopting affiliate of the Plan. The SiEnergy, L.P.401(k) Plan was terminated effective December 31, 2024. Beginning in 2025, eligible employees of Si Investment Co, LLCbecame eligible to participate in the Plan. Effective July 18, 2025, all references to Si Investment Co, LLC were updated to Eligibility rules and entry dates vary primarily based on type of contribution and employment classification (bargaining,non-bargaining, SiEnergy Employee, regular, temporary, and term). The Plan is subject to the provisions of the Employee NW Natural is the plan sponsor and administrator of the Plan. Fidelity Management Trust Company (Fidelity) is the Plan’strustee. Fidelity Workplace Services, LLC performs the recordkeeping duties of the Plan. ContributionsUnder the Plan, participants may elect to contribute, subject to Internal Revenue Code (Code) limitations, up to 50% o