Document:

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                                                                    EXHIBIT 10.2

                              AGREEMENT AND CONSENT

         This AGREEMENT AND CONSENT (this "Agreement"), dated as of November 19,
2001 among Dynegy Inc., an Illinois corporation ("Dynegy"), Dynegy Holdings
Inc., a Delaware corporation ("Dynegy Holdings"), Enron Corp., an Oregon
corporation ("Enron"), CGNN Holding Company, Inc., a Delaware corporation
("CGNN"), MCTJ Holding Co. LLC, a Delaware limited liability company ("MCTJ"),
NNGC Holding Company, Inc., a Delaware corporation ("NNGC Holdings"), Northern
Natural Gas Company, a Delaware corporation ("Northern Natural") (Dynegy, Dynegy
Holdings, Enron, CGNN, MCTJ, NNGC Holdings and Northern Natural being
collectively referred to herein as the "Non-Bank Parties"), Citicorp USA, Inc.
and JPMorgan Chase Bank, as Co-Administrative Agents, and the lenders party to
the Credit Agreement (as defined below) (as defined in such Credit Agreement,
the "Banks").

                                    RECITALS

         A. CGNN, MCTJ, Enron, Dynegy Holdings, and Dynegy are parties to an
Option Agreement, dated as of November 9, 2001 (the "Option Agreement"), as
amended as of November 19, 2001.

         B. On November 9, 2001, Northern Natural filed a Certificate of
Designations of the Series A Preferred Stock (the "Certificate of Designations")
with the Secretary of State of the State of Delaware creating a series of
Northern Natural's Preferred Stock, par value $0.01 per share, designated as the
Series A Preferred Stock (the "Series A Preferred").

         C. On November 13, 2001, Northern Natural issued 1,000 shares of Series
A Preferred to Dynegy.

         D. Northern Natural has entered into a Credit Agreement, dated as of
November 19, 2001, with Citicorp North America, Inc. and JPMorgan Chase Bank, as
Co-Administrative Agents, Citicorp North America, Inc., as Paying Agent,
JPMorgan Chase Bank, as Collateral Trustee and Issuing Bank, and the Banks (as
amended, restated, modified or supplemented from time to time, the "Credit
Agreement"), and various of the parties have entered, or in the future may
enter, into Security Documents (as defined in the Credit Agreement). The Credit
Agreement, the Notes, the Security Documents, the Enron Guaranty, each Notice of
Borrowing, each Notice of Letter of Credit, the ETSC Agreement, the Subordinated
Enron Note, the Fee Letter, the Letter of Credit Documents, the Assumption
Documents and the Corporate Amendment Documents (as each such term is defined in
the Credit Agreement), as amended, restated, modified or supplemented from time
to time, are collectively referred to herein as the "Bank Documents".

         E. The Credit Agreement requires, as a condition precedent to the
extension of credit by the Banks, that the Non-Bank Parties enter into and agree
and consent to the matters set forth in this Agreement.

         F. As an inducement to Dynegy and Dynegy Holdings to enter into this
Agreement, the Banks agree to certain matters set forth in this Agreement.

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         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. Dynegy and Dynegy Holdings approve, pursuant to Section 4.8.7 of the
Option Agreement and Section 5.6 of the Certificate of Designations, the
amendment to the Certificate of Incorporation of Northern Natural attached
hereto as ANNEX A. This approval constitutes a written consent under Section 228
of the Delaware General Corporation Law. Northern Natural agrees promptly to
file the amendment to the certificate of incorporation of northern natural
attached hereto as ANNEX A.

         2. The Non-Bank Parties hereby consent to (a) the execution and
delivery by Enron, NNGC Holdings and Northern Natural (and any other subsidiary
of Enron that is a party to or bound by any Bank Document) of the Bank Documents
on or before the Initial Funding Date (as defined in the Credit Agreement) and
any Security Documents, Notes, Notices of Borrowings and Letter of Credit
Documents thereafter, (b) the borrowing or assumption by Northern Natural of up
to $450 million aggregate principal amount of indebtedness under the Bank
Documents, (c) the grant by NNGC Holdings and Northern Natural of the Liens (as
defined in the Credit Agreement) created under the Bank Documents, (d) the
perfection and maintenance of the Liens created under the Bank Documents and (e)
subject to the terms hereof, the exercise by any Secured Party (as defined in
the Credit Agreement) of its or their remedies pursuant to the Bank Documents or
applicable law, whether by judicial action or otherwise, including, without
limitation, any action to accelerate the Secured Obligations, to commence
insolvency or bankruptcy proceedings against any Loan Party (as defined in the
Credit Agreement), foreclosure, sale in lieu of foreclosure, sale after default
under the Uniform Commercial Code of any relevant state, collection of accounts
or other receivables, offset or the institution of litigation (collectively,
"Remedial Action"). Additionally, such consent shall also constitute a written
consent of Dynegy and Dynegy Holdings given in accordance with Section 228 of
the General Corporation Law of the State of Delaware.

         3. The Non-Bank Parties agree that Northern Natural may incur
indebtedness that is Permitted Refinancing Debt (as defined in the Certificate
of Designations), and use the proceeds thereof to retire the Secured Obligations
(as defined in the Credit Agreement) in accordance with the Credit Agreement.

         4. Except to the extent such payment or distribution is permitted by
the Bank Documents, Dynegy agrees that if it receives any payment or
distribution upon a redemption or repurchase or other acquisition by Northern
Natural of the Series A Preferred prior to (i) the repayment in full in cash of
the non-contingent Secured Obligations, (ii) the termination of all Commitments
(as defined in the Credit Agreement) and (iii) the termination or expiration of
the Letters of Credit (as defined in the Credit Agreement) or, if any Letters of
Credit remain outstanding, the provision of cash collateral or an acceptable
letter of credit in favor of the Issuing Bank (as defined in the Credit
Agreement) to secure the undrawn amount thereunder, such acceptable letter of
credit to be issued by a bank reasonably satisfactory to the Issuing Bank
(hereinafter, such cash collateral or acceptable letter of credit being referred
to as the "LC Collateral Agreements") (the occurrence of items (i), (ii) and
(iii) being referred to as the "Bank Debt Repayment Date") it shall pay over or
deliver to the Paying Agent for the benefit of the

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Secured Parties all such payments or distributions until the occurrence of
the Bank Debt Repayment Date.

         5. Dynegy agrees that if it receives any payment or distribution upon a
liquidation, deemed liquidation, dissolution, winding up, bankruptcy,
insolvency, receivership, reorganization, assignment for the benefit of
creditors or other marshaling of assets or liabilities of Northern Natural prior
to the Bank Debt Repayment Date, it shall pay over or deliver to the Paying
Agent for the benefit of the Secured Parties all such payments or distributions
until the occurrence of the Bank Debt Repayment Date.

         6. If an Event of Default (as defined in the Credit Agreement) or any
other event occurs under the Bank Documents and the Co-Administrative Agents
have actual knowledge thereof, which results in, or gives the Secured Parties
the right to exercise, a Remedial Action (any such Event of Default or such
other event hereinafter called a "Trigger Event"), the Co-Administrative Agents
shall promptly, but in any case within three Business Days (as defined in the
Credit Agreement) after having actual knowledge of such Trigger Event, provide
written notice to Dynegy and Dynegy Holdings of the existence of the Trigger
Event. If the Secured Parties decide to take any Remedial Action as a result of
such Trigger Event, the Co-Administrative Agents shall promptly, but in any case
within three Business Days after such decision to take such Remedial Action,
provide written notice to Dynegy and Dynegy Holdings of the decision to take
such Remedial Action. The Co-Administrative Agents, on behalf of the Secured
Parties, agree not to take any Remedial Action until the Standstill Period (as
hereinafter defined) has ended; provided, however, nothing herein shall prohibit
any Secured Party from exercising during the Standstill Period any right it may
have at law or under the Bank Documents (i) upon the occurrence and during the
continuance of any Trigger Event to take such action as it deems to be
reasonably necessary to maintain the effectiveness, perfection or priority of
its Liens (as defined in the Credit Agreement) under the Bank Documents or (ii)
upon the occurrence and during the continuance of any Trigger Event other than
an Enron Default (as hereafter defined) to exercise its rights and remedies
under the Account Control Agreements (as defined in the Credit Agreement).
During the Standstill Period, Dynegy shall have the right, but not the
obligation, to cure any Event of Default (as defined in the Credit Agreement).
For purposes of this Agreement, "Standstill Period" means the period commencing
on the date a Trigger Event occurs and ending on the earliest of (i) 30 days
after delivering written notice to Dynegy and Dynegy Holdings of their decision
to take any Remedial Action, and (ii) the occurrence of any Event of Default
with respect to Northern Natural under Section 6.01(e) of the Credit Agreement
(the "Standstill Period").

         During the Standstill Period, unless the Trigger Event has been cured
or waived in accordance with the Bank Documents, Dynegy and its assignees shall
have the option, but not the obligation, to purchase from the holders (the
"Holders") of the Secured Obligations (the "Bank Debt") for an amount (the "Bank
Debt Purchase Price") equal to the sum of (a) the principal amount of Bank Debt
then outstanding (excluding the undrawn amount of any outstanding Letters of
Credit), (b) any accrued and unpaid interest on the Bank Debt at the time of
purchase and (c) all accrued and unpaid fees, costs and expenses owed by
Northern Natural under the Bank Documents. In addition, if such option is
exercised, Dynegy will provide for LC Collateral Arrangements. The LC Collateral
Arrangements shall be effected, and the Bank Debt Purchase Price shall be paid
in immediately available funds, in each case collectively in

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exchange for the contemporaneous (i) sale, transfer and assignment by the
Holders to Dynegy or its assignee of all rights and obligations of the
Holders under the Bank Documents as of such date and (ii) delivery to Dynegy
or its assignee of all evidence of the Bank Debt. Such transfer shall be made
pursuant to documentation in form and substance reasonably satisfactory to
all Co-Administrative Agents and Dynegy, and shall be made expressly without
representation or warranty by, or recourse to, the Holders except that the
Holders shall provide a warranty of good title to the Bank Debt, free and
clear of encumbrances. At Dynegy's request and expense, the Holders shall
execute and deliver such other documents as shall be reasonably requested to
so transfer the Bank Debt and the liens and security interests evidenced by
the Security Documents.

         During the Standstill Period, unless the Trigger Event has been cured
or waived by the Secured Parties in accordance with the Bank Documents, in the
event that Dynegy has any senior unsecured long-term debt with an Investment
Grade Rating (as hereinafter defined), Dynegy may at its option, in lieu of
exercising the option contained in the previous paragraph, execute a guarantee
of the Bank Debt or provide a guarantee of the Bank Debt from a Person which
owns greater than 20% of Dynegy's common stock as of the date hereof and at such
time has senior unsecured long-term debt with an Investment Grade Rating, in
either event pursuant to a Guarantee substantially in the form of ANNEX B
attached hereto (any such guarantee herein called an "Alternate Guarantee" and
the Person executing and delivering such Alternate Guarantee is herein called
the "Alternate Guarantor"). If such Alternate Guarantor is not Dynegy, ANNEX B
shall be modified as necessary. An "Investment Grade Rating" means the Person
issuing the Guarantee has at least two of the following ratings: (i) at least
BBB- from Standard & Poor's Rating Group or any successor thereto, (ii) at least
Baa3 from Moody's Investors Service, Inc. or any successor thereto, or (iii) at
least BBB- from Fitch IBCA, Duff & Phelps or any successor thereto. Upon the
execution of such an Alternate Guarantee, any Event of Default under Sections
6.01(b) (as subsection (b) relates to any action by Enron or any ERISA Affiliate
(as defined in the Credit Agreement) other than Northern Natural and its
Subsidiaries under Section 4.01(h) and Section 4.01(m)); 6.01(i); 6.01(j),
6.01(k), and 6.01(l) (as subsections (j), (k) and (l) relate to any ERISA
Affiliate other than Northern Natural and its Subsidiaries); 6.01(m); and
6.01(n)(A), (B) and (C) of the Credit Agreement (each, an "Enron Default") will
automatically be cured and such Events of Default will be amended to substitute
the Alternate Guarantor for Enron as appropriate given the context and
references to Enron in Sections 4.01(m) and 5.02(l) of the Credit Agreement will
be changed to references to the Alternate Guarantor. Upon the execution of such
an Alternate Guarantee on or before the end of the Standstill Period, the Enron
Guaranty and any other guaranty of the Secured Obligations by Enron or any
Subsidiary of Enron (other than Northern Natural and NNGC Holdings) will be
terminated and any such Enron Default shall be deemed cured.

         7. Dynegy and any subsequent holder of shares of the Series A Preferred
agree that they will not sell, assign, transfer, convey or otherwise dispose of
any shares of or interest in the Series A Preferred unless the recipient of such
shares or interest has previously agreed in writing, in form and substance
reasonably satisfactory to the Co-Administrative Agents and delivered to the
Co-Administrative Agents, to become a Non-Bank Party to and be subject to and
bound by this Agreement; provided that no such Assignee of Dynegy shall have the
benefit of the option to provide a guarantee under Section 6 hereof. Dynegy
agrees to submit to Northern Natural for legending in accordance with Section 8
of the Certificate of Amendment to the Restated

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Certificate of Incorporation of Northern Natural, and Northern Natural agrees
to so legend the certificate or certificates representing all of the
outstanding shares of Series A Preferred.

         8.  Each of JPMorgan Chase Bank, Citicorp USA, Inc. and Citicorp North
America, Inc. hereby (i) represents that it has no security interest in the
Pledged Shares (as defined in the Credit Agreement) other than pursuant to the
Security Documents and the Voting Trust Agreements referred to therein and (ii)
agrees that none of Northern Natural, NNGC Holdings and MCTJ has guaranteed any
indebtedness of Enron or its Affiliates (other than MCTJ and its subsidiaries)
to the Banks.

         9.  This Agreement shall be governed by and construed in accordance
with the laws of the State of New York. This Agreement may not be amended
except by an instrument in writing signed by each of the parties hereto.

         10. This Agreement and any amendments hereto may be executed in
counterparts, each of which shall be deemed an original and all of which taken
together shall constitute but a single document.

         11. Except as specifically set forth or referred to herein, nothing
herein is intended or shall be construed to confer upon any Person other than
the parties hereto and their successors or assigns, (including without
limitation any Person that becomes a Secured Party in accordance with the Bank
Documents) any rights or remedies under or by reason of this Agreement.

         12. This Agreement shall be binding upon and inure to the benefit of
each of the parties hereto and their successors and assigns.

         13. Nothing contained in this Agreement shall be deemed to create for
any purpose whatsoever a partnership between the parties hereto or any
fiduciary, agency, joint venture, trust or other similar duties between the
parties hereto.

         14. Nothing herein shall be interpreted to create any liability of
Dynegy for the payment or performance of the Secured Obligations or impose any
liability upon Dynegy due to the occurrence of any Default or Event of Default
(as such terms are defined in the Credit Agreement).

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         This Agreement is executed this 19th day of November, 2001.

                             DYNEGY INC.

                             By:   /s/ Hugh A. Tarpley
                                  ----------------------------------------------
                                  Name: Hugh A. Tarpley
                                  Title: Executive Vice President

                             DYNEGY HOLDINGS INC.

                             By:   /s/ Hugh A. Tarpley
                                  ----------------------------------------------
                                  Name: Hugh A. Tarpley
                                  Title: Executive Vice President

                             ENRON CORP.

                             By:   /s/ Raymond M. Bowen, Jr.
                                  ----------------------------------------------
                                  Name: Raymond M. Bowen, Jr.
                                  Title: Executive Vice President Finance and
                                         Treasurer

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                             CGNN HOLDING COMPANY, INC.

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

                             MCTJ HOLDING CO. LLC

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

                             NNGC HOLDING COMPANY, INC.

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

                             NORTHERN NATURAL GAS COMPANY

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

                             CITICORP NORTH AMERICA, INC.,
                             as Co-Administrative Agent

                             By:   /s/ J. Christoper Lyons
                                  ----------------------------------------------
                                  Name: J. Christoper Lyons
                                  Title:  Vice President

                             JPMORGAN CHASE BANK,
                             as Co-Administrative Agent and as a Bank

                             By:   /s/ Robert Anastasio
                                  ----------------------------------------------
                                  Name: Robert Anastasio
                                  Title: Vice President

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                             CITICORP USA, INC.,
                             as a Bank

                             By:   /s/ J. Christoper Lyons
                                  ----------------------------------------------
                                  Name: J. Christoper Lyons
                                  Title:  Vice President<Page>

                                                                    Exhibit 10.3

                     AMENDMENT TO PURCHASE OPTION AGREEMENT

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

                                    RECITALS

         A.   On November 9, 2001, the Enron Parties, the Company, NNGC and the
Dynegy Parties entered into a Purchase Option Agreement (the "Purchase Option
Agreement").

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

         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.   The last sentence of Section 2.1 of the Purchase Option Agreement
is hereby amended in its entirety to provide as follows:

         The Purchase Option must be exercised for all the Option Interests and
         all the Preferred Shares simultaneously if the Closing under the Option
         Agreement occurred pursuant to Section 2.5.1.1, 2.5.1.2, 2.5.1.3 or
         2.5.1.4 of the Option Agreement (a "Merger Termination Option Closing")
         and must be exercised for the Option Interests only if the Closing
         under the Option Agreement occurred pursuant to Section 2.5.1.5 of the
         Option Agreement (an "Event of Default Option Closing").

         2.   Section 2.2 of the Purchase Option Agreement is hereby amended in
its entirety to provide as follows:

              2.2. OPTION TERM. The Purchase Option shall be exercisable (a)
         until the later of (i) 180 days after the date hereof and (ii) 90 days
         after a Closing under the Option Agreement upon an exercise pursuant to
         Section 2.5.1.4 thereof or (b) until 90 days after a Closing under the
         Option Agreement pursuant to Section 2.5.1.1, 2.5.1.2, 2.5.1.3 or
         2.5.1.5 thereof (the "Option Term"). If the Purchase Option has not
         been exercised prior to the expiration of the Option Term, then the
         rights and obligations set forth in this Agreement shall expire and
         terminate.

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         3.   Section 2.3 of the Purchase Option Agreement is hereby amended in
its entirety to provide as follows:

              2.3 EXERCISE PRICE OF PURCHASE OPTION. (a) The exercise price
         of the Purchase Option for the Option Interests (the "Option Interests
         Exercise Price") shall be the total sum of (i) $24 million, PLUS (ii)
         $950 million, MINUS (iii) the aggregate amount of outstanding principal
         indebtedness under the Bank Credit Facility and the Senior Notes and
         any Permitted Refinancing Debt related thereto on the Closing Date,
         PLUS (iv) the positive or negative change in Working Capital calculated
         from the most recent Closing Date of the Option Agreement to the
         Estimated Working Capital based on the definition of Working Capital
         provided in this Agreement, MINUS (v) any increase in long-term debt
         (other than Debt referred to in (iii) above) between the most recent
         closing under the Option Agreement and the Closing under this
         Agreement, PLUS (vi) any decrease in long-term Debt (other than Debt
         referred to in (iii) above) between the most recent closing under the
         Option Agreement and the Closing under this Agreement, PLUS (vii) any
         accrued but unpaid dividends on the Series A Preferred Stock as of the
         most recent Closing under the Option Agreement.

         Notwithstanding the foregoing, in the event that the Purchase Option
         for the Option Interests is exercised following an Event of Default
         Option Closing, the Option Interests Exercise Price shall be adjusted
         to exclude any accrued but unpaid dividends on the Series A Preferred
         Stock as of the Closing under the Option Agreement and any accrued but
         unpaid dividends on the Series A Preferred Stock since such Closing to
         the extent such dividends increased the principal amount of the
         Intercompany Note Receivable.

         4.   Section 3.3.3 of the Purchase Option Agreement is hereby
amended to replace the words "and the Series A Stock" with "and, if
applicable, the Series A Preferred Stock."

         5.   Section 3.4.1 of the Purchase Option Agreement is hereby
amended to insert the words ", if applicable," immediately before the words
"the Series A Exercise Price."

         6.   Section 3.4.2 of the Purchase Option Agreement is hereby
amended to insert the words ", if applicable," immediately before the words
"Dynegy shall deliver."

         7.   Section 4.3 of the Purchase Option Agreement is hereby amended
to delete the word "Purchase" before the words "Option Term" in the second
line thereof.

         8.   Sections 4.4.4, 4.4.5, 4.4.6, 4.4.8 and 4.4.9 of the Purchase
Option Agreement are hereby amended in their entirety to provide as follows:

              4.4.4.  MERGERS.  Merge or consolidate, or enter into an agreement
         providing for any merger or consolidation, with any Person if the
         holders of NNGC's 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;

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<Page>

              4.4.5.  SALE OF ASSETS. Except as provided in Schedule 4.4.5,
         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;

              4.4.6.  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;

              4.4.8.  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;

              4.4.9.  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;

         9.   Section 5.1.3 of the Purchase Option Agreement is hereby amended
to insert the words ", if applicable," before the words "the Series A Preferred
Stock."

         10.  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;

                                       3
<Page>

         (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.

                                       4
<Page>

         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

                                   NORTHERN NATURAL GAS COMPANY,
                                   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

                                       5
<Page>

                                   DYNEGY INC.,
                                   an Illinois corporation

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

                                       6

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