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                                                                   EXHIBIT 10.15


                            SOUTHWEST GAS CORPORATION

                               BOARD OF DIRECTORS

                                 RETIREMENT PLAN


                            Effective January 1, 1988
                          Amended Effective May 9, 1990
                 Amended and Restated Effective October 1, 1993
                  Amended and Restated Effective March 1, 1999

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                            SOUTHWEST GAS CORPORATION
                       BOARD OF DIRECTORS RETIREMENT PLAN


                                     PURPOSE

The principal objective of this Board of Directors Retirement Plan is to ensure
that a competitive level of retirement income is paid in order to attract and
retain Directors of Southwest Gas Corporation. The Plan is designed to provide a
benefit that will meet this objective. Eligibility for participation in the Plan
shall be limited to outside, non-employee Directors retiring after January 1,
1988. The original Plan was effective on January 1, 1988, and amended May 9,
1990, October 1, 1993 and March 1, 1999.


                                 I. DEFINITIONS

1.1      "Board" means the Board of Directors of the Company.

1.2      "Change in Control" means the first to occur of any of the following
         events:

         (a)      Any "person" (as the term is used in Sections 13 and 14(d)(2)
                  of the Securities Exchange Act of 1934 ("Exchange Act")) who
                  becomes a beneficial owner (as that term is used in Section
                  13(d) of the Exchange Act), directly or indirectly, of 50% or
                  more of the Company's capital stock entitled to vote in the
                  election of directors; or

         (b)      During any period of not more than two consecutive years, not
                  including any period prior to the adoption of this Plan,
                  individuals who, at the beginning of such period constitute
                  the board of directors of the Company, and any new director
                  (other than a director designated by a person who has entered
                  into an agreement with the Company to effect a transaction
                  described in clause (a) of this Section 1.2) whose election by
                  the board of directors or nomination for election by the
                  Company's shareholders was approved by a vote of at least
                  three-fourths (3/4ths) of the directors then still in office,
                  who either were directors at the beginning of the period or
                  whose election or nomination for election was previously
                  approved, cease for any reason to constitute at least a
                  majority thereof.

1.3      "Committee" means the Compensation Committee of the Board to which the
         Board has given authority to administer the Plan. After a Change in
         Control, the Committee shall cease to have any powers under the Plan
         and all powers previously vested in the Committee under the Plan will
         then be vested in the Third Party Fiduciary.

1.4      "Company" means Southwest Gas Corporation and any Successor
         Corporation.


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1.5      "Director" means an outside, non-employee member of the board of
         directors of Southwest Gas Corporation prior to a Change in Control.

1.6      "Effective Date" previously was October 1, 1993. This amended and
         restated Plan is effective March 1, 1999.

1.7      "Participant" means an outside, non-employee Director. Inside Directors
         and retired employees of the Company are excluded from participation in
         the Plan.

1.8      "Plan" is the Southwest Gas Board of Directors Retirement Plan as
         described in this document.

1.9      "Retiree" means a former Director eligible for receiving benefits from
         the Plan.

1.10     "Retire" or "Retirement" means the termination of a Director's service
         on the Board on one of the dates specified in Section II.

1.11     "Successor Corporation" means any corporation or other legal entity
         which is the successor to Southwest Gas Corporation, whether resulting
         from merger, reorganization or transfer of substantially all of the
         assets of Southwest Gas Corporation, regardless of whether such entity
         shall expressly agree to continue the Plan.

1.12     "Third Party Fiduciary" means an independent third party (a corporate
         entity with no other relationship with the Company) selected by the
         Company to take over the administration of the Plan upon and after a
         Change in Control and to determine appeals of claims denied under the
         Plan before and after a Change in Control pursuant to a Third Party
         Fiduciary Services Agreement.

1.13     "Third Party Fiduciary Services Agreement" means the agreement with the
         Third Party Fiduciary to perform services with respect to the Plan.

1.14     "Trust Agreement" means an agreement establishing a "grantor trust" of
         which the Company is the grantor, within the meaning of subpart E, part
         I, subchapter J, chapter 1, subtitle A of the Internal Revenue Code of
         1986, as amended (the "Code").

1.15     "Trust Fund or Funds" means the assets of every kind and description
         held under any Trust Agreement forming a part of the Plan.

1.16     "Trustee" means any person or entity selected by the Company to act as
         trustee under any Trust Agreement at any time of reference.

1.17     "Years of Service" means the length of time, in discrete 12-month
         periods, a Participant has served on the board of directors of
         Southwest Gas Corporation.


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                          II. ELIGIBILITY FOR BENEFITS

2.1      Each Participant is eligible to Retire and receive a benefit under this
         Plan beginning on one of the following dates, provided he qualifies:

         (a)      "Normal Retirement Date," which is the first day of the month
                  following the month in which the Participant reaches age 65,
                  provided he has at least ten Years of Service.

         (b)      "Mandatory Retirement Date," which is the first day of the
                  month following the month in which the Participant reaches age
                  72.

         (c)      "Postponed Retirement Date," which is the first day of the
                  month following the Participant's Normal Retirement Date, but
                  no later than the Mandatory Retirement Date, in which the
                  Participant terminates service on the Board, provided he has
                  at least ten Years of Service.

         (d)      "Disability Retirement Date," which is the first day of the
                  month following the month in which the Participant's total and
                  permanent disability began, as determined by the Committee,
                  but no later than the Participant's Normal Retirement Date,
                  provided he has at least ten Years of Service at the time of
                  the disability.

2.2      A Participant is eligible to take "Early Retirement" from the Board
         prior to age 65 provided he has at least ten Years of Service. The
         Participant taking "Early Retirement" will be eligible to receive
         benefits pursuant to Section 3.3 when he reaches age 65.

2.3      Notwithstanding the foregoing and upon the occurrence of a Change in
         Control, a Participant will Retire immediately prior to such an event
         and receive the Normal Retirement Benefit beginning the first day of
         the month following such an event, provided he has at least eight Years
         of Service at such time.


                   III. AMOUNT AND FORM OF RETIREMENT BENEFIT

3.1      Normal Retirement Benefit. The annual benefit payable under the Plan
         will be the amount of the Participant's annual retainer fee on his
         Normal Retirement Date and will be paid for life.

3.2      Mandatory Retirement Benefit. The annual benefit payable under the Plan
         will be the amount of the Participant's annual retainer fee on his
         Mandatory Retirement Date and will be paid for life.

3.3      Early Retirement Benefit. The annual benefit payable for Early
         Retirement under the Plan will be the amount of the Participant's
         annual retainer fee on his Early


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         Retirement date and will be paid for life commencing when the
         Participant reaches age 65.

3.4      Postponed Retirement Benefit. The annual benefit payable at a Postponed
         Retirement Date under the Plan will be the amount of the Participant's
         annual retainer fee on the date of his postponed retirement and will be
         paid for life.

3.5      Disability Retirement Benefit. The annual benefit under the Plan for a
         totally and permanently disabled Participant, payable at a Disability
         Retirement Date, will be the amount of the Participant's annual
         retainer fee on the date of the disability and will be paid for life.

3.6      Discretionary Benefits. The Board may, at its sole discretion, grant to
         an eligible Participant an increased benefit of $1,000 per year for
         life for each ten-year period of service beyond the minimum qualifying
         service period of ten years.


                       IV. PAYMENT OF RETIREMENT BENEFITS

4.1      One-quarter of the benefit determined in accordance with Section III
         will be payable on the first day of each calendar quarter. The initial
         benefit payment will be paid at the time of Retirement or within 30
         days thereof, and will be prorated for a partial quarter if the
         Retirement date is not on the first day of a quarter.

4.2      Benefit payments will cease on the first day of the calendar quarter
         following the Retiree's death.


                              V. NO DEATH BENEFITS

5.1      No benefits are payable under this Plan in the event of death.


                                   VI. GENERAL

6.1      Amounts payable to a Participant shall be paid from the general assets
         of the Company or from the assets of a grantor trust within the meaning
         of subpart E, part I, subchapter J, chapter 1, subtitle A of the Code,
         established for use in funding executive compensation arrangements and
         commonly known as a "Rabbi Trust."

6.2      The Company shall have no obligation under the Plan to a Participant,
         except as provided in this Plan.

6.3      The Participant must cooperate with the Committee in furnishing all
         information requested by the Company to facilitate the payment of his
         benefit.


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6.4      Participants and their heirs, successors, and assigns shall have no
         legal or equitable rights, claims, or interest in any specific property
         or assets of the Company. No assets of the Company shall be held under
         any trust, or held in any way as collateral security for the fulfilling
         of the obligations of the Company under the Plan. Any and all of the
         Company's assets shall be, and remain, the general unpledged,
         unrestricted assets of the Company. The Company's obligation under the
         Plan shall be merely that of an unfunded and unsecured promise of the
         Company to pay money in the future, and the rights of the Participants
         shall be no greater than those of unsecured general creditors. It is
         the intention of the Company that this Plan (and the Trust Funds
         described in Section VII) be unfunded for purposes of the Code.

6.5      There shall be deducted from each payment made under the Plan or other
         compensation payable to the Participant all taxes which are required to
         be withheld by the Company in respect to such payment or this Plan. The
         Company shall have the right to reduce any payment (or other
         compensation) by the amount of cash sufficient to provide the payment
         amount of said taxes.

6.6      The Company is without power to lawfully assure a Participant continued
         tenure as a Director, and nothing herein constitutes a contract for
         continuing service between the Company and the Participant.


                                   VII. TRUSTS

7.1      The Company may maintain one or more Trust Funds to finance all or a
         portion of the benefits under the Plan by entering into one or more
         Trust Agreement(s). Any Trust Agreement is designated as, and shall
         constitute, a part of the Plan, and all rights which may accrue to any
         person under the Plan shall be subject to all the terms and provisions
         of such Trust Agreement. A Trustee shall be appointed by the Committee
         or the Board and shall have such powers as provided in the Trust
         Agreement. The Committee or the Board may modify any Trust Agreement,
         in accordance with its terms, to accomplish the purposes of the Plan
         and appoint a successor Trustee under the provisions of such Trust
         Agreement. By entering into such Trust Agreement, the Committee or the
         Board may vest in the Trustee, or in one or more investment managers
         (as defined in ERISA), the power to manage and control the Trust Fund.
         The Committee's authority under the provisions of this Section 7.1 will
         cease with a Change in Control.


            VIII. TERMINATION, AMENDMENT OR MODIFICATION OF THE PLAN

8.1      The Board may, at any time, without notice, amend or modify the Plan in
         whole or in part; provided, however, that: (i) no amendment or
         modification shall be effective to decrease or restrict (a) the benefit
         the Participant qualifies for under the provisions of the Plan, or (b)
         benefit payments to Participants once such payments


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         have commenced; and (ii) effective March 1, 1999, no amendment or
         modification of this Section VIII, Section X, or Section XI of the Plan
         shall be effective.

8.2      The Board shall not terminate the Plan until all benefits have been
         paid in full under the provisions of the Plan.


                   IX. RESTRICTIONS ON ALIENATION OF BENEFITS

9.1      To the maximum extent permitted by law, no interest or benefit under
         the Plan shall be assignable or subject in any manner to alienation,
         sale, transfer, claims of creditors, pledge, attachment, or
         encumbrances of any kind.


                          X. ADMINISTRATION OF THE PLAN

10.1     Except as otherwise provided in this Section X, and subject to Section
         XI, the general administration of the Plan, as well as construction and
         interpretation thereof, shall be vested in the Committee. Specifically,
         the Committee shall have the discretion and authority to: (a) make,
         amend, interpret, and enforce all appropriate rules and regulations for
         the administration of the Plan; and (b) decide or resolve any and all
         questions including interpretations of the Plan. Any individual serving
         on the Committee who is a Participant shall not vote or act on any
         matter relating solely to himself or herself. The number of members of
         the Committee shall be established by, and the members shall be
         appointed from time to time by, and shall serve at the pleasure of, the
         Board of Directors. Members of the Committee may be Participants under
         the Plan.

10.2     Upon and after a Change in Control, the administration of the Plan
         shall be vested in a Third Party Fiduciary, as provided for herein and
         pursuant to the terms of a Third Party Fiduciary Services Agreement.
         Any Third Party Fiduciary Services Agreement is designated as, and
         shall constitute, a part of the Plan. The Third Party Fiduciary shall
         also have the discretion and authority to: (a) make, amend, interpret,
         and enforce all appropriate rules and regulations for the
         administration of the Plan; and (b) decide or resolve any and all
         questions including interpretation of the Plan and the Trust Agreement.
         Except as otherwise provided for in any Trust Agreement, the Third
         Party Fiduciary shall have no power to direct the investment of Plan or
         Trust Funds or select any investment manager or custodial firm for the
         Plan or Trust Agreement. The Company shall pay all reasonable
         administrative expenses and fees of the Third Party Fiduciary when it
         acts as the administrator of the Plan or pursuant to Section XI. The
         Third Party Fiduciary may not be terminated by the Company without the
         consent of 50% of the Participants in the Plan.

10.3     In the administration of the Plan, the Committee or the Third Party
         Fiduciary, as the case may be, may from time to time employ such
         agents, consultants, advisors, and managers as it deems necessary or
         useful in carrying out its duties as it sees fit (including acting
         through a duly authorized representative) and may from to time to time
         consult with counsel to the Company.


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10.4     The decision or action of the Committee or the Third Party Fiduciary,
         as the case may be, with respect to any question arising out of or in
         connection with the administration, interpretation, and application of
         the Plan (and the Trust Agreement to the extent provided for in Section
         10.2) and the rules and regulations promulgated hereunder shall be
         final and conclusive and binding upon all persons having any interest
         in the Plan.

10.5     The Company shall indemnify and save harmless each member of the
         Committee, the Third Party Fiduciary, and any employee of the Company
         to whom the duties of the Committee may be delegated against any and
         all claims, losses, damages, expenses, and liabilities arising from any
         action or failure to act with respect to the Plan, except in the case
         of fraud, gross negligence, or willful misconduct by the Committee, any
         of its members, the Third Party Fiduciary, or any such employee.

10.6     To enable the Committee and the Third Party Fiduciary to perform their
         functions, the Company shall supply full and timely information to the
         Committee and the Third Party Fiduciary, as the case may be, on all
         matters relating to the compensation of all Participants, their
         Retirement, death or other cause for termination of service, and such
         other pertinent facts as the Committee or the Third Party Fiduciary may
         require.


                              XI. CLAIMS PROCEDURE

11.1     Any Participant (such Participant being referred to below as a
         "Claimant") may deliver to the Committee a written claim for
         determination with respect to benefits available to such Claimant from
         the Plan. The claim must state with particularity the determination
         desired by the Claimant.

11.2     The Committee shall consider a claim and notify the Claimant within 90
         calendar days after receipt of a claim in writing:

         (a)      That the Claimant's requested determination has been made, and
                  that the claim has been allowed in full; or

         (b)      That the Committee has reached a conclusion contrary, in whole
                  or in part, to the Claimant's requested determination, and
                  such notice must set forth in a manner calculated to be
                  understood by the Claimant: (i) the specific reason(s) for the
                  denial of the claim, or any part thereof; (ii) the specific
                  reference(s) to pertinent provisions of the Plan upon which
                  the denial was based; (iii) a description of any additional
                  material or information necessary for the Claimant to perfect
                  the claim, and an explanation of why such material or
                  information is necessary; and (iv) an explanation of the claim
                  review procedure set forth in Section 11.3.


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11.3     Within 60 days after receiving a notice from the Committee that a claim
         has been denied, in whole or in part, a Claimant (or the Claimant's
         duly authorized representative) may file with the Third Party Fiduciary
         a written request for a review of the denial of the claim. Thereafter,
         the Claimant (or the Claimant's duly authorized representative) may
         review pertinent documents, submit written comments or other documents,
         and request a hearing, which the Third Party Fiduciary, in its sole
         discretion, may grant.

11.4     The Third Party Fiduciary shall render its decision on review promptly,
         and not later than 60 days after the filing of a written request for
         review of a denial, unless a hearing is held or other special
         circumstances require additional time, in which case the Third Party
         Fiduciary's decision must be rendered within 120 calendar days after
         such date. Such decision must be written in a manner calculated to be
         understood by the Claimant, and it must contain: (i) the specific
         reason(s) for the decision; (ii) the specific reference(s) to the
         pertinent Plan provisions upon which the decision was based; and (iii)
         such other matters as the Third Party Fiduciary deems relevant.

11.5     A Claimant's compliance with the foregoing provisions of this Section
         XI is a mandatory prerequisite to a Claimant's right to commence any
         legal action with respect to any claim for benefits under the Plan.


                               XII. MISCELLANEOUS

12.1     No Director will participate in an action of the Committee or the Board
         on a matter that solely applies to that Director. Such matters will be
         determined by a majority of the rest of the Committee or the Board.

12.2     Each Participant will receive a copy of this Plan, and the Committee
         will make available for any Participant's inspection a copy of the
         rules and regulations the Committee uses in administering the Plan.

12.3     This Plan is established under, and will be construed according to, the
         laws of the state of Nevada.

12.4     The Plan shall be binding upon the Company and any of its successors
         and assigns, and upon a Participant, Participant's beneficiary,
         assigns, heirs, executors, and administrators.

12.5     Masculine pronouns wherever used shall include feminine pronouns and
         when the context dictates, the singular shall include the plural.

12.6     In case any provision of the Plan shall be held illegal or invalid for
         any reason, said illegality or invalidity shall not affect the
         remaining parts hereof, but the Plan shall be construed and enforced as
         if such illegal and invalid provisions had never been inserted herein.

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12.7     Any notice given under the Plan shall be in writing and shall be mailed
         or delivered to:

                                    SOUTHWEST GAS CORPORATION
                                    Board of Directors Retirement Plan
                                    Compensation Committee
                                    5241 Spring Mountain Road
                                    Las Vegas, NV  89102
         and

                                    CRG Fiduciary Services, Inc.
                                    633 West Fifth Street, 53rd floor
                                    Los Angeles, CA 90071-2086
                                    Attn: Managing Director

IN WITNESS WHEREOF, the Company has executed this Amended and Restated Board of
Directors Retirement Plan this 30th day of July 1999.

                                         SOUTHWEST GAS CORPORATION



                                         By
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                                                     Thomas Y. Hartley
                                               Chairman of Board of Directors



                                         By
                                             -----------------------------------
                                                      Michael O. Maffie
                                             President & Chief Executive Officer


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