QuickLinks -- Click here to rapidly navigate through this document Exhibit 99.12 TRANSPORTATION SERVICE AGREEMENT Contract Identification FT18150 This Transportation Service Agreement (Agreement) is entered into by Great Lakes Gas Transmission Limited Partnership (Transporter) and ANR PIPELINE COMPANY (Shipper). WHEREAS, Shipper has requested Transporter to transport Gas on its behalf and Transporter represents that it is willing to transport Gas under the terms and conditions of this Agreement. NOW, THEREFORE, Transporter and Shipper agree that the terms below constitute the transportation service to be provided and the rights and obligations of Shipper and Transporter. 1. EFFECTIVE DATE: November 01, 2016 2. CONTRACT IDENTIFICATION: FT18150 3. RATE SCHEDULE: FT 4. SHIPPER TYPE: Interstate Pl 5. STATE/PROVINCE OF INCORPORATION: Delaware 6. TERM: November 01, 2014 to October 31, 2017 7. EFFECT ON PREVIOUS CONTRACTS: This Agreement supersedes, cancels and terminates, as of the effective date stated above, the following contract(s): Service Agreement dated November 01, 2015 with Contract Identification FT18150. 8. MAXIMUM DAILY QUANTITY (Dth/Day): 101,300 Please see Appendix A for further detail. 9. RATES: Unless Shipper and Transporter have agreed to a rate other than the maximum rate, rates shall be Transporter's maximum rates and charges plus all applicable surcharges in effect from time to time under the applicable Rate Schedule (as stated above) on file with the Commission unless otherwise agreed to by the parties in writing. Provisions governing a Rate other than the maximum shall be set forth in this Paragraph 9 and/or on Appendix B hereto. 10. POINTS OF RECEIPT AND DELIVERY: The primary receipt and delivery points are set forth on Appendix A. 11. RELEASED CAPACITY: N/A 12. INCORPORATION OF TARIFF INTO AGREEMENT: This Agreement shall incorporate and in all respects be subject to the "General Terms and Conditions" and the applicable Rate Schedule (as stated above)