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                                                                    Exhibit 10.1



                          AMENDMENT TO OPTION AGREEMENT


         This AMENDMENT TO OPTION AGREEMENT (this "Amendment") dated as of
November 19, 2001 is by and among CGNN Holding Company, Inc., a Delaware
corporation (the "Grantor"), MCTJ Holding Co. LLC, a Delaware limited liability
company (the "Company"), Enron Corp., an Oregon corporation ("Enron"), Dynegy
Holdings Inc., a Delaware corporation (the "Grantee"), and Dynegy Inc., an
Illinois corporation ("Dynegy").

                                    RECITALS

         A.       On November 9, 2001, the Grantor, the Company, Enron, the
Grantee and Dynegy entered into an Option Agreement (the "Option Agreement").

         B.       The parties to the Option Agreement now desire to amend the
Option Agreement as specified below.

         C.       The Grantor, the Company, Enron, the Grantee, Dynegy, NNGC
Holding Company, Inc., a Delaware corporation, Northern Natural Gas Company, a
Delaware corporation, and the lenders party thereto the Credit Agreement are
parties to an Agreement and Consent, dated as of November 19, 2001 (the
"Agreement and Consent").

         NOW THEREFORE, in consideration of the mutual agreements herein
contained and other good and valuable consideration, the sufficiency of which is
hereby acknowledged, the parties hereby agree as follows:

         1.       Section 2.3 of the Option Agreement is hereby amended to add a
new last sentence as follows:

                  Notwithstanding the foregoing, in the event the Option is
                  exercised after a closing under the Purchase Option Agreement,
                  the Exercise Price shall be adjusted as appropriate to include
                  only those changes in Estimated Working Capital since the
                  closing under the Purchase Option Agreement.

         2.       Section 2.4 of the Option Agreement is hereby amended to add a
new penultimate sentence as follows:

                  If the Option becomes exercisable pursuant to Section 2.5.1.5
                  but ceases to be exercisable pursuant thereto or if the
                  Grantee exercises the Option pursuant to Section 2.5.1.5 but
                  Grantor purchases the Option Interests pursuant to the
                  Purchase Option Agreement, the Option will remain or once
                  again become exercisable in accordance with its terms until
                  the expiration of the Option Term.

         3.       The Option Agreement is hereby amended to add a new
Section 2.5.1.5 as follows:

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                  2.5.1.5. the earlier to occur of (i) the moment in time
                           immediately prior to the expiration of the Standstill
                           Period (as defined in the Agreement and Consent) or
                           (ii) the moment in time immediately prior to the
                           exercise by Dynegy of its rights under either the
                           second or third paragraphs of Section 6 of the
                           Agreement and Consent, PROVIDED, HOWEVER, that the
                           Grantee may not exercise the Option pursuant to this
                           Section 2.5.1.5 if prior to such time all Events of
                           Default under the Credit Agreement that permitted the
                           Option to be exercisable under this Section 2.5.1.5
                           shall have been waived or shall have been cured other
                           than as a result of the exercise by Dynegy of its
                           rights under either the second or third paragraphs of
                           Section 6 of the Agreement and Consent.

         4.       The Option Agreement is hereby amended to add a new
Section 2.7 as follows:

                  2.7  SALE OF THE OPTION. If the Option is exercisable pursuant
         to Section 2.5 and the conditions to closing in Section 3.3 have not
         been satisfied, the Grantee (in addition to any rights Dynegy has
         pursuant to Section 8.4 of the Subscription Agreement) will have the
         right to sell the Option to any other Person in a transaction that
         complies with the Securities Act.

         5.       Section 4.5 of the Option Agreement is hereby amended in its
entirety to provide as follows:

                  4.5  FORGIVENESS OF DEBT OWED BY ENRON. After the Exercise and
         prior to the Closing, the Company will, and will cause NNGC to, cancel
         and forgive all indebtedness owed to the Company or any of its
         Subsidiaries by Enron or its Affiliates (other than the Company and
         NNGC Holdings), other than a net amount of such debt equal to $240
         million plus any dividends (whether or not declared) accrued and unpaid
         on the shares of Series A Preferred Stock at such time. The remaining
         outstanding indebtedness will be evidenced by a note of Enron to NNGC
         in substantially the form of Exhibit A and, in the event that the
         Option is exercised after a closing under the Purchase Option
         Agreement, the note so evidencing the remaining indebtedness shall
         replace the note issued in connection with the initial exercise of the
         Option. For purposes of this Section 4.5, "indebtedness" shall include
         any liability of Enron or its Affiliates (other than the Company and
         NNGC Holdings) under Section 18-607 of the Delaware Limited Liability
         Company Act or otherwise to return to the Company any portion of the
         distribution of up to $1,950 million made by the Company to the Grantor
         from the proceeds of one or more loans from NNGC.

         6.       Sections 4.8.4, 4.8.5, 4.8.6, 4.8.8 and 4.8.9 of the Option
Agreement are hereby amended in their entirety to provide as follows:

                  4.8.4.  MERGERS. Merge or consolidate, or enter into an
         agreement providing for any merger or consolidation, with any Person if
         the holders of its


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         capital stock prior to the transaction will own capital stock
         representing less than 100% of the voting power of the surviving entity
         after the transaction;

                  4.8.5.  SALE OF ASSETS. Except as provided in Schedule 4.8.5,
         sell, lease or otherwise dispose of any of its assets, other than (i)
         obsolete equipment or inventory, (ii) assets sales in the Ordinary
         Course of Business not to exceed an aggregate of $20 million within any
         12-month period and (iii) the grant of Liens (as defined in the Credit
         Agreement) created under the Loan Documents (as defined in the Credit
         Agreement) and any sales or other dispositions with respect to assets
         covered by such Liens pursuant to the exercise by the Paying Agent, the
         Collateral Trustee, the Co-Administrative Agents or any Bank (all as
         defined in the Credit Agreement) of its remedies in respect of the
         Collateral (as defined in the Credit Agreement) pursuant to the Loan
         Documents, including foreclosure, sale in lieu of foreclosure or the
         institution of litigation;

                  4.8.6.  LIQUIDATION; DISSOLUTION; BANKRUPTCY. (i) Dissolve or
         liquidate, in whole or in part, (ii) pursuant to or within the meaning
         of Title 11 of the United States Code or any similar federal, state or
         foreign law for the relief of debtors, commence a voluntary case or
         consent to the entry of an order for relief against it in an
         involuntary case, (iii) consent to the appointment of a receiver,
         trustee, assignee, liquidator or similar official of it or for all or
         substantially all of its property, (iv) make a general assignment for
         the benefit of its creditors, (v) admit in writing its inability to pay
         its debts generally as they become due, or (vi) take any corporate
         action in furtherance of any action set forth in items (i) through (v)
         hereof;

                  4.8.8.  INVESTMENTS AND LOANS. Make any Investment in any
         Person or any loans or advances to, or guarantees for the benefit of,
         any Person, other than (i) loans to any wholly owned Subsidiary, (ii)
         loans to MCTJ Holding Co. LLC and the assumption of Debt of Enron,
         provided that the aggregate principal amount of such loans and assumed
         Debt does not exceed $1,950 million, (iii) loans pursuant to the Cash
         Management Program and (iv) Investments, loans, advances and guarantees
         made in the Ordinary Course of Business;

                  4.8.9.  INDEBTEDNESS.  Create, incur, assume or suffer to
         exist, or permit any of its Subsidiaries to create, incur, assume or
         suffer to exist, Debt, other than (i) the Debt outstanding as of the
         date hereof, (ii) Debt in an aggregate principal amount not exceeding
         $450 million outstanding at any time pursuant to the Loan Documents and
         (iii) Permitted Refinancing Debt;

         7.       The Option Agreement is hereby amended to add a new
Section 4.8.12 as follows:

                  4.8.12.  AMENDMENTS TO CREDIT AGREEMENTS. Make any amendment
         to any credit agreement, security document, mortgage or evidence of
         indebtedness that would have the effect of (a) restricting the ability
         of NNGC to make distributions on or payments in respect of the Series A
         Preferred Stock beyond any restrictions contained in the Loan Documents
         as of the date hereof or (b)


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         designating as an event of default thereunder the exercise by the
         Grantee of the Option.

         8.       The Option Agreement is hereby amended to add a new
Section 4.9 as follows:

                  4.9.  INFORMATION. Enron, Grantor and the Company shall
         promptly furnish to the Grantee as soon as possible and in any event
         within five days after an executive officer of NNGC having obtained
         knowledge thereof, notice of the occurrence of any Event of Default or
         any Default (each as defined in the Credit Agreement), in each case
         continuing on the date of such notice, and a statement of the Senior
         Vice President and Treasurer of the NNGC setting forth details of such
         Event of Default or Default and the action which the NNGC has taken and
         proposes to take with respect thereto.

         9.       The Option Agreement is hereby amended to add new
Sections 5.2.17 and 5.2.18 as follows:

                  5.2.17.  NNGC COMMON STOCK. The shares of common stock of
         NNGC are not subject to any Liens, except Liens created pursuant to the
         Security Documents (as defined in the Credit Agreement).

                  5.2.18.  GUARANTEES. None of NNGC, NNGC Holdings and the
         Company has guaranteed or taken responsibility for the payment of any
         Debt of Enron or any Affiliate of Enron (other than Debt of the Company
         and Subsidiaries of the Company).

         10.      Section 9.8 of the Option Agreement is hereby amended in its
entirety to provide as follows:

                  9.8.  ASSIGNMENT. Neither this Agreement nor any of the
         rights, interests or obligations hereunder or under the Option shall be
         sold, assigned or otherwise disposed of or transferred by either of the
         parties hereto (whether by operation of law or otherwise) without the
         prior written consent of the other party, except that the Grantee may
         assign this Agreement to an Affiliate or Subsidiary of the Grantee or
         to any purchaser of the Option pursuant to Section 2.7; PROVIDED,
         HOWEVER, that no such assignment shall have the effect of releasing the
         Grantee from its obligations hereunder (except upon a sale of the
         Option pursuant to Section 2.7) and the assignee shall be subject to
         all of the terms and conditions of this Agreement as if it were the
         Grantee. Subject to the preceding sentence, this Agreement shall be
         binding upon, inure to the benefit of and be enforceable by the parties
         and their respective successors and assigns. Any assignee must become a
         party to and be bound by the Agreement and Consent

         11.      As used in this Amendment:

         (a)      "capital stock representing voting power" and similar
phrases refer to capital stock or similar equity securities which in ordinary
circumstances vote in the election of directors of a corporation or similar
body of an entity with another organizational form;


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         (b)      "Investment" as applied to any Person means (a) any direct
or indirect purchase or other acquisition by such Person of any notes,
obligations, instruments, stock, securities or ownership interest of any other
Person and (b) any capital contribution by such Person to any other Person; and

         (c)      "Credit Agreement" means the Credit Agreement dated as of
November 19, 2001 among Northern Natural Gas Company, a Delaware corporation,
the banks named therein, Citicorp North America, Inc. as Paying Agent,
JPMorgan Chase Bank as Collateral Trustee and Issuing Bank and Citicorp North
America, Inc. and JPMorgan Chase Bank as Co-Administrative Agents, as amended,
restated, modified or supplemented from time to time.


























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         IN WITNESS WHEREOF, the parties hereto have caused this Amendment to be
signed by their respective officers thereunto duly authorized, all as of the day
and year first written above.


                                     ENRON CORP.,
                                     an Oregon corporation


                                     By:       /s/ Raymond M. Bowen, Jr.
                                               ---------------------------------
                                               Name: Raymond M. Bowen, Jr.
                                               Title: Authorized Agent



                                     CGNN HOLDING COMPANY, INC.,
                                     a Delaware corporation


                                     By:       /s/ Kevin A. Howard
                                               ---------------------------------
                                               Name: Kevin A. Howard
                                               Title: Authorized Agent



                                     MCTJ HOLDING CO. LLC,
                                     a Delaware limited liability company


                                     By:       /s/ Kevin A. Howard
                                               ---------------------------------
                                               Name: Kevin A. Howard
                                               Title: Authorized Agent



                                     DYNEGY HOLDINGS INC.,
                                     a Delaware corporation


                                     By:       /s/ Hugh A. Tarpley
                                               ---------------------------------
                                               Name: Hugh A. Tarpley
                                               Title: Authorized Agent



                                     DYNEGY INC.,
                                     an Illinois corporation


                                     By:       /s/ Hugh A. Tarpley
                                               ---------------------------------
                                               Name: Hugh A. Tarpley
                                               Title: Authorized Agent


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