PUBLIC NOTICE NOTICE OF FILING OF THE ENVIRONMENTAL MANAGEMENT AND CONSTRUCTION PLAN FOR THE NATIONAL GRID BEAVER RIVER - PORTER 115 kV TRANSMISSION REBUILD PROJECT BEAVER RIVER SUBSTATION Case No. 25-T-0178 - Petition of Niagara Mohawk Power Corporation d/b/a National Grid for a Certificate of Environmental Compatibility and Public Need, Pursuant to Article VII, for the Reconstruction of Approximately 60.32 Miles of 115kV Transmission Line from New Beaver River Substation in the Town of Croghan, Lewis County, to the Porter Substation in the Town of Marcy, Oneida County. On or about May 26, 2026, Niagara Mohawk Power Corporation d/b/a National Grid ("National Grid") intends to file with the Public Service Commission (the "Commission") a proposed Environmental Management and Construction Plan for the Beaver River Substation (the "Beaver River Substation EM&CP"), which is part of the Beaver River - Porter 115 kV Transmission Rebuild Project (the "Project"). The Beaver River Substation EM&CP focuses on construction of the proposed Beaver River Substation in the Town of Croghan, New York. The Project is National Grid's proposal to rebuild several circuits, which when combined, will provide two (2) new 115 kilovolt ("kV") transmission lines between the new Beaver River Substation in the Town of Croghan, Lewis County, to the existing Porter Substation in the Town of Marcy, Oneida County for a distance of approximately 60.32 miles, as well as the construction of the new Beaver River Substation in the Town of Croghan, Oneida County, and the construction of the new Gulf Road Substation in the Town of Leyden, Oneida County. The Project traverses the Towns of Croghan, New Bremen, Watson, Lowville, Martinsburg, Turin, West Turin, and Leyden, and the Villages of Croghan, Lowville, and Turin in Lewis County, and the Towns of Boonville, Steuben, Floyd, Trenton, and Marcy, and the Villages of Boonville and Holland Patent in Oneida County. National Grid will file an EM&CP for the transmission line and construction of the Gulf Road Substation at a later date and will publish a separate notice of filing at that time. The Project, including construction of the Beaver River Substation, will bring the Beaver River – Porter transmission line up to current National Electrical Safety Code standards, and will improve the safety, performance, and reliability of the National Grid transmission system. CONTENTS OF THE BEAVER RIVER SUBSTATION EM&CP The Beaver River Substation EM&CP describes the construction procedures and environmental protection measures to be implemented during Project construction. Per the Specifications included as Appendix E to the Joint Proposal, the EM&CP consists of a narrative which provides a description of the Project and the statement of objectives, techniques, procedures, and requirements for the Project (satisfying Section A of the Specifications), Plan and Profile drawings in Appendix A (satisfying Section B of the Specifications) and other Plans in the remaining Appendices (satisfying Section C of the Specifications). The Beaver River Substation EM&CP has been developed to comply with the negotiated Joint Proposal, which was filed with the Commission on or about May 22, 2026, and which National Grid expects will be adopted by the Commission. The Beaver River Substation EM&CP complies with Appendix E of the Joint Proposal, which contains the Specifications for the Development of the Environmental Management and Construction Plan, as provided by Department of Public Service Staff ("DPS Staff") for this Project. An electronic version the Beaver River Substation EM&CP will be available for public inspection online on the Commission's Document and Matter Management ("DMM") page for Case 25-T-0178 at the following location: https://documents.dps.ny.gov/public/MatterManagement/ CaseMaster.aspx?MatterCaseNo=25-t-0178&CaseSearch=Search The electronic version of the Beaver River Substation EM&CP can also be accessed by visiting the Commission's website (www.dps.ny.gov), hovering over the "Commission Files" tab, clicking the "File Search" button, and entering "25-T-0178" in the "Search by Case Number" box. The Beaver River Substation EM&CP will also be available for public inspection (in electronic copy) during normal business hours at the following local libraries and municipal buildings: Croghan Free Library (9794 State Route 812, Croghan, New York 13327), Village of Croghan (9578 Park Drive, Croghan, New York 13327), Lowville Free Library (5387 Dayan Street, Lowville, New York 13367), Lyons Falls Library (3918 High Street, Lyons Falls, New York 13368), Martinsburg-William H. Bush Memorial Library (5605 Whitaker Road, Martinsburg, New York 13404), Port Leyden Community Library (3145 Canal Street, Port Leyden, New York 13433), Turn – B. Elizabeth Library (6312 East Main Street, Turin, New York 13473), Holland Patent Free Library (9580 Main Street, Holland Patent, New York 13354), Erwin Library and Institute (104 Schuyler Street, Boonville, New York 13309), Didymus Thomas Memorial Library (9639 Main Street, Remsen, New York 13438), and Barneveld Free Library (118 Boon Street, Barneveld, New York 13304). DESCRIPTION OF THE PROJECT The Project is a rebuild several circuits, which when combined, will provide two (2) new 115 kilovolt ("kV") transmission lines between the new Beaver River Substation in the Town of Croghan, Lewis County, to the existing Porter Substation in the Town of Marcy, Oneida County for a distance of approximately 60.32 miles, as well as the construction of the new Beaver River Substation in the Town of Croghan, Oneida County, and the construction of the new Gulf Road Substation in the Town of Leyden, Oneida County. The Project traverses the Towns of Croghan, New Bremen, Watson, Lowville, Martinsburg, Turin, West Turin, and Leyden, and the Villages of Croghan, Lowville, and Turin in Lewis County, and the Towns of Boonville, Steuben, Floyd, Trenton, and Marcy, and the Villages of Boonville and Holland Patent in Oneida County. The proposed work in the Beaver River Substation EM&CP includes construction of the Beaver River Substation on a site located on Effley Falls Road in the Town of Croghan, Lewis County. The Beaver River Substation will encompass approximately 6.74 acres. The construction will impact undeveloped public service land owned by National Grid. NEED FOR THE PROJECT The Accelerated Renewable Energy Growth and Community Benefit Act requires electric transmission upgrades to meet the clean energy and climate goals established under the Climate Leadership and Community Protection Act ("CLCPA"). To meet the CLCPA goals, the paths between the proposed Beaver River Substation and the existing Porter Substation must be upgraded to accommodate increased renewable generation in the area. National Grid determined that constructing the proposed Beaver River Substation is the most feasible option. The Project will rebuild 115 kV elements to increase the amount of energy the circuits can transmit from generation to load, or from generation to system on ramps that move the power out of local area. The proposed rebuild of these transmission elements will be done in accordance with a comprehensive, state-of-the-art design incorporating transmission structures that meet National Grid's standards and will increase the reliability of the electric grid. COMMENTS, COMPLAINTS, AND FURTHER INFORMATION Any person may be heard by the Commission on any matter or objection regarding the proposed Beaver River Substation EM&CP by filing written comments with the Commission Secretary and National Grid (at the addresses immediately below) within twenty-one (21) days of (i) the date the proposed Beaver River Substation EM&CP was filed with the Commission or (ii) the date of the newspaper publication of this notice, whichever is later. Please reference Case No. 25-T-0178 when making any comments, complaints or requesting further information regarding the Project. Hon. Michelle L. Phillips Secretary to the Commission New York State Public Service Commission Agency Building 3 Albany, NY 12223-1350 Lizette Lewis Project Engagement National Grid 300 Erie Blvd W Syracuse, New York 13202 lizette.lewis@nationalgrid.com Phone: 315-870-5273 Public Service Commission Website: www.dps.ny.gov The National Grid agent or employee who will receive complaints, if any, during the construction of the Project is Lizette Lewis, whose contact information is immediately above. Any person desiring additional information about a specific geographical location or specific subject may request it from National Grid by contacting Lizette Lewis. Any request for additional information should be specific as to the subject of the information desired. May 24 2026 LNYS0524759