Fiscal Agency Agreement, dated as of July 12, 2018, by and between Northern Natural Gas Company and The Bank of New York Mellon Trust Company, N.A., Fiscal Agent, relating to the $450,000,000 in principal amount of the 4.30% Senior Bonds due 2049

Except as otherwise set forth in this Agreement, the Securities offered and sold in their initial resale distribution to a qualified institutional buyer (as defined in Rule 144A (“Rule 144A”) under the United States Securities Act of 1933, as amended (the “Act”), each a “QIB”) in reliance on Rule 144A (“Rule 144A Securities”) shall initially be issued in the form of one or more Global Securities (as defined in Section 1(e) hereof) in definitive, fully registered form, substantially in the form set forth on Exhibit A, with such applicable legends as are provided for herein and on Exhibit A, and in minimum denominations of $2,000 and in integral multiples of $1,000 in excess of $2,000. Such Global Securities shall be duly executed by the Issuer and authenticated by the Fiscal Agent as hereinafter provided, and deposited with the U.S. Depository (as defined in Section 1(e) hereof). Until such time as the Holding Period (as defined below) shall have terminated, each such Security shall be referred to as a “Rule 144A Global Security.” The aggregate principal amount of any Rule 144A Global Security may be adjusted by endorsements to Schedule A on the reverse thereof in any situation where adjustment is permitted or required by this Agreement or provided for on Exhibit A. Unless the Issuer determines otherwise in accordance with applicable law, the legend setting forth transfer restrictions shall be removed or deemed removed from a Rule 144A Security in accordance with the procedures set forth in Section 1(d) after such time as the applicable Holding Period shall have terminated, and each such Security shall thereafter be held as an unrestricted Security. As used herein, the term “Holding Period,” with respect to Rule 144A Securities, means the period referred to in Rule 144(d) under the Act or any successor provision thereto (“Rule 144(d)”) and as may be amended or revised from time to time, beginning from the later of (i) the original issue date of such Securities or (ii) the last date on which the Issuer or any affiliate of the Issuer was the beneficial owner of such Securities (or any predecessor thereof).

Except as otherwise set forth in this Agreement, Securities offered and sold in reliance on Regulation S under the Act (“Regulation S”) will be issued initially in the form of one or more temporary Global Securities in the form provided for herein and on Exhibit A, with such applicable legends as are provided for herein and on Exhibit A, and in minimum denominations of $2,000 and in integral multiples of $1,000 in excess of $2,000 equal to the outstanding principal amount of the Securities initially sold in reliance on Rule 903 of Regulation S under the Act (the “Regulation S Temporary Global Securities”). The Regulation S Temporary Global Securities, which will be deposited on behalf of the purchasers of the Securities represented thereby with the Fiscal Agent, as custodian for the U.S. Depository,

Except as otherwise provided in this Agreement, upon resale of the Securities to purchasers who are institutional “accredited investors” as described in Rule 501(a)(1), (2), (3) or (7) under the Act and who are not QIBs shall be issued in the form of fully registered, definitive, physical certificates, substantially in the form set forth herein and on Exhibit A, with such applicable legends as are provided for on Exhibit A, and in minimum denominations of $200,000 and in integral multiples of $1,000 in excess of $200,000 (such securities are herein referred to as “Restricted Definitive Securities”). Unless the Issuer determines otherwise in accordance with applicable law, the legend setting forth transfer restrictions shall be removed or deemed removed from a Restricted Definitive Security in accordance with the procedures set forth in Section 1(d) after such time as the applicable Holding Period shall have terminated, and each such Security shall thereafter be held as an unrestricted Security. As used herein, the term “Holding Period,” with respect to Restricted Definitive Securities, means the period referred to in Rule 144(d) or any successor provision thereto and as may be amended or revised from time to time, beginning from the later of (i) the original issue date of such Securities or (ii) the last date on which the Issuer or any affiliate of the Issuer was the beneficial owner of such Securities (or any predecessor thereof).

Transfer Through a Rule 144A Global Security. If the holder of a beneficial interest in a Regulation S Global Security wishes at any time to transfer such interest to a Person who wishes to take delivery thereof in the form of a beneficial interest in a Rule 144A Global Security, such transfer may be effected, subject to the Applicable Procedures, only in accordance with this Section 5(d)(i), provided, however, that prior to the expiration of the Distribution Compliance Period, transfers of beneficial interests in the Regulation S Temporary Global Securities may not be made to a U.S. person (as defined under Regulation S) or for the account or benefit of a U.S. person (other than an initial purchaser). Upon receipt by the U.S. Depository of

Interests in Regulation S Global Security Initially to be Held Through Euroclear or Clearstream. Beneficial interests in a Regulation S Temporary Global Security may be held only through Agent Members acting for and on behalf of Euroclear or Clearstream.

Transfer Through Restricted Definitive Security. If the holder of a beneficial interest in a Regulation S Global Security wishes at any time to transfer such interest to a Person who wishes to take delivery thereof in the form of a Restricted Definitive Security, such transfer may be effected, subject to the Applicable Procedures, only in accordance with this Section 5(d)(iii), provided, however, that in no

Transfer Through an Unrestricted Global Security. If the holder of a beneficial interest in a Regulation S Global Security wishes at any time to transfer such interest to a Person who wishes to take delivery thereof in the form of a beneficial interest in an unrestricted Global Security, such transfer may be effected, subject to the Applicable Procedures, only in accordance with this Section 5(d)(iv). Upon receipt by the U.S. Depository of the instructions, order and certificate set forth below, the U.S. Depository shall promptly forward the same to the Transfer Agent at the Corporate Trust Office. Upon receipt by the Transfer Agent from the U.S. Depository at the Corporate Trust Office of (1) written instructions given in accordance with the Applicable Procedures from an Agent Member directing the U.S. Depository to cause to be credited to a specified Agent Member’s account a beneficial interest in the unrestricted Global Security equal to that of the beneficial interest in the Regulation S Global Security to be so transferred, (2) a written order given in accordance with the Applicable Procedures containing information regarding the account

Beneficial Interests in Regulation S Temporary Global Securities to Definitive Securities. Notwithstanding the foregoing, a beneficial interest in a Regulation S Temporary Global Security may not be exchanged for a definitive Security or transferred to a Person who takes delivery thereof in the form of a definitive Security prior to (A) the expiration of the Distribution Compliance Period and (B) the receipt by the Registrar of any certificates required pursuant to Rule 903(b)(3)(ii)(B) under the Act, except in the case of a transfer pursuant to an exemption from the registration requirements of the Act other than Rule 903 or Rule 904.

Transfer Through a Regulation S Global Security. If the holder of a beneficial interest in a Rule 144A Global Security wishes at any time to transfer such interest to a Person who wishes to take delivery thereof in the form of a beneficial interest in a Regulation S Global Security, such transfer may be effected, subject to the Applicable Procedures, only in accordance with this Section 5(e)(i). Upon receipt by the U.S. Depository of the instructions, order and certificate set forth below, the U.S. Depository shall promptly forward the same to the Transfer Agent at the Corporate Trust Office. Upon receipt by the Transfer Agent from the U.S. Depository at the Corporate Trust Office of (1) written instructions given in accordance with the

Transfer Through Restricted Definitive Security. If the holder of a beneficial interest in a Rule 144A Global Security wishes at any time to transfer such interest to a Person who wishes to take delivery thereof in the form of a Restricted Definitive Security, such transfer may be effected, subject to the Applicable Procedures, only in accordance with this Section 5(e)(ii). Upon receipt by the U.S. Depository of the instructions and certificate set forth below, the U.S. Depository shall promptly forward the same to the Transfer Agent at the Corporate Trust Office. Upon receipt by the Transfer Agent from the U.S. Depository at the Corporate Trust Office of (1) written instructions given in accordance with the Applicable Procedures from an Agent Member directing the U.S. Depository to cause to be issued a Restricted Definitive Security to such Person in a principal amount equal to that of the beneficial interest in the Rule 144A Global Security to be so transferred and (2) a certificate substantially in the form set forth in or contemplated by Exhibit F given by the transferor of such beneficial interest and, if the transferee is an institutional “accredited

Transfer Through an Unrestricted Global Security. If the holder of a beneficial interest in a Rule 144A Global Security wishes at any time to transfer such interest to a Person who wishes to take delivery thereof in the form of a beneficial interest in an unrestricted Global Security, such transfer may be effected, subject to the Applicable Procedures, only in accordance with this Section 5(e)(iii). Upon receipt by the U.S. Depository of the instructions, order and certificate set forth below, the U.S. Depository shall promptly forward the same to the Transfer Agent at the Corporate Trust Office. Upon receipt by the Transfer Agent from the U.S. Depository at the Corporate Trust Office of (1) written instructions given in accordance with the Applicable Procedures from an Agent Member directing the U.S. Depository to cause to be credited to a specified Agent Member’s account a beneficial interest in the unrestricted Global Security equal to that of the beneficial interest in the Rule 144A Global Security to be so transferred, (2) a written order given in accordance with the Applicable Procedures containing information regarding the account of the Agent Members to be credited with, and the account of the Agent Members to be debited for, such beneficial interest, and (3) a certificate substantially in the form set forth in or contemplated by Exhibit G given by the transferor of such beneficial interest, the Transfer Agent shall (A) reduce the principal amount of the Rule 144A Global Security, and increase the principal amount of the unrestricted Global Security, in each case by an amount equal to the principal amount of the beneficial interest in the Rule 144A Global Security to be so transferred, as evidenced by appropriate endorsements on Schedule A of the respective Global Securities and (B) instruct the U.S. Depository, (x) to make corresponding reductions and increases to the transferor’s beneficial interests in the respective Global Securities and (y) to cause to be credited to the account of the Person specified in such instructions a beneficial

Transfer Through Regulation S Global Security. If the holder of a Restricted Definitive Security wishes at any time to transfer such interest to a Person who wishes to take delivery thereof in the form of a beneficial interest in a Regulation S Global Security, such transfer may be effected, subject to the Applicable Procedures, only in accordance with this Section 5(f)(i). Upon receipt by the Transfer Agent at the Corporate Trust Office of (1) written instructions from the transferor directing it to cause the U.S. Depository to cause to be credited to such Person a beneficial interest in the Regulation S Global Security in a principal amount equal to that of the Restricted Definitive Security to be so transferred and (2) a certificate substantially in the form set forth in or contemplated by Exhibit H given by the transferor of such Restricted Definitive Security, the Transfer Agent shall (A) increase the principal amount of the Regulation S Global Security by an amount equal to the principal amount of the beneficial interest in the Regulation S Global Security to be received by such Person, as evidenced by appropriate endorsement on Schedule A of the Regulation S Global Security, and cancel such Restricted Definitive Security, and (B) instruct the U.S. Depository, (x) to make corresponding increases in the amount represented by the Regulation S Global Security and (y) to cause to be credited to the account of the Person specified in such instructions a beneficial interest in the Regulation S Global Security having a principal amount equal to the principal amount of the Restricted Definitive Security that was cancelled.

Transfer Through Rule 144A Global Security. If the holder of a Restricted Definitive Security wishes at any time to transfer such

Transfer Through Unrestricted Global Security. If the holder of a Restricted Definitive Security wishes at any time to transfer such interest to a Person who wishes to take delivery thereof in the form of a beneficial interest in the unrestricted Global Security, such transfer may be effected, subject to the Applicable Procedures, only in accordance with this Section 5(f)(iii). Upon receipt by the Transfer Agent at the Corporate Trust Office of (1) written instructions from the transferor directing it to cause the U.S. Depository to cause to be credited to such Person a beneficial interest in the unrestricted Global Security in a principal amount equal to that of the Restricted Definitive Security to be so transferred and (2) a certificate substantially in the form set forth in or contemplated by Exhibit H given by the transferor of such Restricted Definitive Security, the Transfer Agent shall (A) increase the principal amount of the unrestricted Global Security by an amount equal to the principal amount of the beneficial interest in the unrestricted Global Security to be received by such Person, as evidenced by appropriate endorsement on Schedule A of the unrestricted Global Security, and cancel such Definitive Security, and (B) instruct the U.S. Depository, (x) to make corresponding increases in the amount represented by the Rule 144A Global Security and (y) to cause to be credited to the

Transfer Through Restricted Definitive Security. If the holder of a Restricted Definitive Security wishes at any time to transfer such interest to a Person who wishes to take delivery thereof in the form of another Restricted Definitive Security, such transfer may be effected, subject to the Applicable Procedures, only in accordance with this Section 5(f)(iv). Upon receipt by the U.S. Depository of the instructions and certificate set forth below, the U.S. Depository shall promptly forward the same to the Transfer Agent at the Corporate Trust Office. Upon receipt by the Transfer Agent from the U.S. Depository at the Corporate Trust Office of a certificate substantially in the form set forth in or contemplated by Exhibit H given by the transferor of such Restricted Definitive Security and, if the transferee is an institutional “accredited investor” (as defined in Rule 501(a)(1), (2), (3) or (7) under the Securities Act), a certificate substantially in the form set forth in or contemplated by Exhibit I given by such transferee, the Transfer Agent shall register the transfer of such Restricted Definitive Security.

Securities in exchange for or in lieu of Securities of like tenor and of like form which become mutilated, destroyed, stolen or lost; and

registered Securities of authorized denominations in exchange for a like aggregate principal amount of Securities of like tenor and of like form.

Securities theretofore canceled by the Fiscal Agent or delivered to the Fiscal Agent for cancellation or held by the Fiscal Agent for reissuance but not reissued by the Fiscal Agent;

Securities which have become due and payable at maturity or otherwise and with respect to which monies sufficient to pay the principal thereof and any interest thereon shall have been made available to the Fiscal Agent;

Securities which have been defeased pursuant to Section 15(b) hereof; or

Securities in lieu of or in substitution for which other Securities shall have been authenticated and delivered pursuant to this Agreement;

The Issuer shall irrevocably have deposited or caused to be deposited with a trustee, who may be the Fiscal Agent and who shall agree to comply with the provisions of this Section 15 applicable to it (the “Defeasance Trustee”), as trust funds in trust for the purpose of making the following payments, specifically pledged as security for, and dedicated solely to, the benefit of the holders of the Securities, (A) money in an amount, or (B) U.S. Government Obligations and/or Eligible Obligations which through the scheduled payment of principal and interest in respect thereof in accordance with their terms will provide, not later than one day before the due date of any payment, money in an amount, or (C) a combination thereof, sufficient, in the opinion of a nationally recognized firm of independent public accountants expressed in a written certification thereof delivered to the Defeasance Trustee, to pay and discharge, and which shall be applied by the Defeasance Trustee to pay and discharge, the principal of, premium, if any, and each installment of interest on the Securities not later than one day before the stated maturity of such principal or installment of interest in accordance with the terms of this Agreement and of the Securities. For this purpose: “U.S. Government Obligations” means securities that are (x) direct obligations of the United States of America for the payment of which its full faith and credit are pledged or (y) obligations of a Person controlled or supervised by and acting as an agency or instrumentality of the United States of America the payment of which is unconditionally guaranteed as a full faith and credit obligation by the United States of America, which, in either case, are not callable or redeemable at the option of the issuer thereof, and shall also include a depository receipt issued by a bank (as defined in Section 3(a)(2) of the Act) as custodian with respect to any such U.S. Government Obligation or a specific payment of principal of or interest on any such U.S. Government Obligation held by such custodian for the account of the holder of such depository receipt, provided that (except as required by law) such custodian is not authorized to make any deduction from the amount payable to the holder of such depository receipt from any amount received by the custodian in respect of the U.S. Government Obligation or the specific payment of principal of or interest on the U.S. Government Obligation evidenced by such

In the case of an election under Section 15(b), the Issuer shall have delivered to the Defeasance Trustee an opinion of counsel stating that (x) the Issuer has received from, or there has been published by, the U.S. Internal Revenue Service a ruling, or (y) since the date of this Agreement there has been a change in the applicable U.S. Federal income tax law, in either case to the effect that, and based thereon such opinion shall confirm that, the holders of the Outstanding Securities will not recognize income, gain or loss for U.S. Federal income tax purposes as a result of such deposit, defeasance and discharge and will be subject to U.S. Federal income tax on the same amount, in the same manner and at the same times as would have been the case if such deposit, defeasance and discharge had not occurred.

In the case of an election under Section 15(c), the Issuer shall have delivered to the Defeasance Trustee an opinion of counsel to the effect that the holders of the Outstanding Securities will not recognize income, gain or loss for U.S. Federal income tax purposes as a result of such deposit and Covenant Defeasance and will be subject to U.S. Federal income tax on the same amount, in the same manner and at the same times as would have been the case if such deposit and Covenant Defeasance had not occurred.

No event of default under paragraph 7 of the Securities or event which with notice or lapse of time or both would become such an event of default shall have occurred and be continuing on the date of such deposit or, insofar as paragraphs 7(iv) and (v) of the Securities are concerned, at any time during the period ending on the 121st day after the date of such deposit (it being understood that this condition shall not be deemed satisfied until the expiration of such period).

Such Defeasance or Covenant Defeasance shall not result in a breach or violation of or constitute a default under, any other agreement or instrument to which the Issuer is a party or by which it is bound.

The Issuer shall have delivered to the Fiscal Agent and the Defeasance Trustee an Officers’ Certificate and an opinion of counsel, each stating that all conditions precedent provided for relating to either the Defeasance under Section 15(b) or the Covenant Defeasance under Section 15(c) (as the case may be) have been complied with.

Such Defeasance or Covenant Defeasance shall not result in the trust arising from such deposit constituting an investment company as defined in the United States Investment Company Act of 1940, as amended, or such trust shall be qualified under such act or exempt from regulation thereunder.