<PAGE>

                                                               EXHIBIT 10(u)(18)

                    CENTERPOINT ENERGY, INC. RETIREMENT PLAN

            (As Amended and Restated Effective as of January 1, 1999)

                                Seventh Amendment

                  CenterPoint Energy, Inc., a Texas corporation (the "Company"),
having reserved the right under Section 15.1 of the CenterPoint Energy, Inc.
Retirement Plan, as amended and restated effective as of January 1, 1999, and as
thereafter amended (the "Plan"), to amend the Plan, does hereby amend certain
provisions of the Plan relating to the NorAm Energy Corp. Employees Retirement
Plan (the "NorAm Plan"), which was merged with and into the Plan effective as of
January 1, 1999, as in effect on such date, that continue to apply with respect
to certain "Grandfathered Benefits" under the Plan for participants who had a
benefit under the NorAm Plan prior to January 1, 1999, effective as of January
1, 2003, as follows:

                  1.       The first sentence of Section 4.5 of the NorAm Plan
document is hereby amended to read as follows:

         "Notwithstanding any other provision of this Article, the retirement
         benefit payable to a Participant will not be less than the retirement
         benefit that the Participant had accrued as of December 31, 1991 (or,
         if the Participant commenced benefits before January 1, 2003 and was a
         Super Highly Compensated Employee for any Plan Year before 1992, as of
         his Benefit Protection Date as hereafter defined) under the terms of
         the Retirement Plan in effect on December 31, 1988 (including early
         retirement age and factors and other actuarial assumptions), determined
         as if the Participant had a Separation from Service on December 31,
         1991, or his Benefit Protection Date, whichever applies."

                  2.       Section 4.9 of the NorAm Plan document is hereby
amended in its entirety to read as follows:

                  "4.9     Special Rule - Preservation of Prior Formula. For any
         Participant who commences retirement benefits on or after January 1,
         2003, the retirement benefit will be the greater of (i) the retirement
         benefit determined under the foregoing provisions of this Article for
         all years of Credited Service or (ii) the retirement benefit the
         Participant would be entitled to receive under the Retirement Plan
         formula applicable to such Participant on December 31, 1991 (as if this
         Plan had not been adopted, including all relevant early retirement
         factors and actuarial assumptions) applied to the same Credited Service
         period as applied to (i) above.

                                       1

<PAGE>

                  Notwithstanding, the retirement benefit of any other
         Participant who (i) was not a Highly Compensated Employee (as defined
         in Code Section 414(q)) on December 31, 1991, and (ii) was an active
         Employee on December 31, 1991, or had a Separation from Service prior
         to such date and is later rehired under circumstances in which his
         prior service is taken into account under Article 2, will be the
         greater of (1) the benefit determined under the foregoing provisions of
         this Article for all years of Credited Service or (2) in lieu of such
         benefit, the benefit the Participant would be entitled to receive under
         the Retirement Plan formula applicable to such Participant on December
         31, 1991 (as if this Plan had not been adopted, including all relevant
         early retirement factors and actuarial assumptions, except as otherwise
         provided in this Section), applied to the period of Credited Service
         ending with the close of the Plan Year (after 1991) in which the
         Participant first becomes a Highly Compensated Employee. For purposes
         of determining benefits accruing under this Section in Plan Years
         beginning after 1994, Section 4.5(a) of the benefit formula under Part
         Three of the Retirement Plan will be applied by replacing `5 years of
         Vesting Service' with `10 years of Vesting Service.' If a Participant
         is entitled to a benefit under this Section, the benefit will be
         payable only in the forms of payment applicable under Article 5, except
         to the extent that a form of payment provided under the Retirement Plan
         is protected under Section 5.10."

                  IN WITNESS WHEREOF, CenterPoint Energy, Inc. has caused these
presents to be executed by its duly authorized officer in a number of copies,
all of which shall constitute one and the same instrument, which may be
sufficiently evidenced by any executed copy hereof, this 5th day of November
2003, but effective as of the date specified above.

                                  CENTERPOINT ENERGY, INC.

                                  By: /s/ David M. McClanahan
                                      ------------------------------------
                                      David M. McClanahan
                                      President and Chief Executive Officer

ATTEST:

/s/ Richard B.Dauphin
---------------------------
Assistant Secretary

                                       2