TSP Name: Northern Natural Gas Company TSP: 784158214 Notice ID: 099409 Notice Type: TSP Capacity Offering Subject: OPEN SEASON FOR VIKING PIERZ INSIDE BRAINERD LAKE/CROSBY BRANCH LINE Critical: N Post Date/Time: 12/05/2025 09:00 AM Notice Status: Initiate For Gas Day(s): 12/05/2025 - 12/11/2025 Notice Effective Date/Time: 12/05/2025 09:00 AM Notice End Date/Time: 12/11/2025 05:00 PM Required Response Indicator Description: 5-No response required Notice Text: Open Season Overview Northern Natural Gas Company (Northern) is hereby soliciting binding bids for up to 5,000 Dth/day (See attached map) of annual firm throughput service from Viking/NNG Pierz Inter (POI 61667) for delivery to points on the Brainerd Lake/Crosby Branch Line in Northern's Market Area commencing on October 1, 2026. The bid quantity must be equal for each month across the term of the bid. The actual capacity available will be determined based on the specific delivery point(s) requested in the open season. Interested customers may request firm throughput service by submitting a signed binding Bid Form. Customers requesting service are responsible for ensuring arrangements have been made for any capacity necessary on any upstream or downstream pipeline for their volumes to be confirmed during the nomination and scheduling process. Capacity awarded requires a flow order that restricts all receipts from Viking/NNG Pierz Inter (POI 61667) to be delivered to points on the Brainard Lake/Crosby Line. Northern will award capacity in a manner consistent with the Open Season Procedures discussed below. Northern filed a Section 4 rate case on July 1, 2025, to recover the asset modernization and maintenance capital being invested in its pipeline system to comply with pipeline safety requirements and maintain reliability of service to its customers. This filing reflects an increase to the maximum rates. Increased rates become effective January 1, 2026. Open Season Timing Commenced: December 5, 2025 Closes: December 11, 2025, at 5:00 p.m. CCT To be considered in the open season, customers' signed binding Bid Form must be received by the close of the open season. If you have any questions, please contact your Account Manager or Jason Thomsen at (402) 398-7469. Open Season Procedures Submit your binding Bid Form to Northern by either: Facsimile to (402) 398-7413 Email to NNGOpenSea@nngco.com The Bid Form must include: Requested rate Receipt point - Viking/NNG Pierz Inter (POI 61667) Delivery point(s) on the Brainerd Lake/Crosby Branch Line Volume In-service date Term Minimum amount of capacity willing to accept, if applicable Increments of capacity willing to accept, if applicable Contingencies, if applicable The reservation rate bid is binding for firm throughput service. The term of service for any bid must end on a March 31 or an October 31. The bid quantity must be equal for each month during the term of the bid. Capacity will be awarded to the highest bid(s) based on a determination of the best bid, or combination of bids that result in the highest net present value (NPV) of reservation revenue, on a per unit of capacity basis, using revenues from the start of the service through October 31, 2028. Northern has the right to aggregate bids or portions of bids, that generate the highest total NPV to Northern. The NPV per unit will be determined by discounting the cash flow (using the FERC interest rate) generated from the reservation rate multiplied by the volume for each month, by bid, and then dividing the NPV by the maximum daily quantity bid. The following receipt point will be considered in this open season: Viking/NNG Pierz Inter (POI 61667) . The following delivery points will be considered in this open season: Points on the Brainerd Lake/Crosby Branch Line Capacity awarded requires a flow order that restricts all receipts from Viking/NNG Pierz Inter (POI 61667) to be delivered to points on the Brainard Lake/Crosby Line. Northern reserves the right to reject any bid(s) less than maximum rates. Northern reserves the right to reject any bid(s) which are subject to contingencies, including the construction of minor facilities. Capacity awarded in the open season may require a new contract. Transportation contracts are to be executed by customers within thirty (30) calendar days of tender by Northern. Northern and customer may agree to amend the service agreement, as allowed by Northern's Tariff, at any time after award of the capacity. Northern will evaluate and award capacity for incremental bids based on the terms of this open season. Customer(s) must meet the creditworthiness provisions of Northern's Tariff. Upon request by Northern, customer shall provide appropriate credit assurance, including credit assurance for the construction of facilities, within ten (10) calendar days of Northern's request. If a non-creditworthy customer fails to provide the appropriate security, Northern may award the capacity to the next best bid(s) or proceed to remarket the capacity, and customer will be liable for any difference in value of the bids, in addition to any other remedies available by law. The results of this open season will be posted on Northern's website.