Document:

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                                                                   EXHIBIT 10.13

                            SOUTHWEST GAS CORPORATION

                             EXECUTIVE DEFERRAL PLAN

                             Effective March 1, 1986

                       Amended and Restated March 1, 1988

                       Amended and Restated March 1, 1989

                       Amended and Restated March 1, 1990

                      Amended and Restated October 29, 1992

                        Amended and Restated May 10, 1994

                  Amended and Restated Effective March 1, 1999

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                              MASTER PLAN DOCUMENT
                SOUTHWEST GAS CORPORATION EXECUTIVE DEFERRAL PLAN

                                     PURPOSE

The purpose of this Plan is to provide specified benefits to a select group of
key employees who contribute materially to the continued growth, development and
future business success of SOUTHWEST GAS CORPORATION.

                                    ARTICLE 1
                                   DEFINITIONS

For purposes hereof, unless otherwise clearly apparent from the context, the
words and phrases listed below shall be defined as follows:

1.1      "Account Balance" means a Participant's individual fund comprised of
         Deferrals, Company Contributions and interest earnings credited thereon
         up to the time of Benefit Distribution.

1.2      "Base Annual Salary" means the yearly compensation paid to an
         Executive, excluding bonuses, commissions, overtime, and nonmonetary
         awards for employment services to the Company.

1.3      "Beneficiary" means the person or persons, or the estate of a
         Participant, named to receive any benefits under the Plan upon the
         death of a Participant.

1.4      "Benefit Account Balance" shall have the meaning set forth in Article
         5.3.

1.5      "Benefit Distribution" means the date benefits under the Plan commence
         or are paid in full to a Participant, or because of his death, to his
         Beneficiary, which will occur within 90 days of notification to the
         Company of the event that gives rise to such distribution.

1.6      "Board of Directors" means the Board of Directors of Southwest Gas
         Corporation and any Successor Corporation.

1.7      "Bonus" means the portion of actual awards, if any, paid in cash under
         the terms of Southwest Gas Corporation's 1993 Management Incentive
         Plan, as amended ("Management Incentive Plan").

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

         (a)      Any "person" (as the term is used in Section 13 and 14(d)(2)
                  of the Securities Exchange Act of 1934 ("Exchange Act"))
                  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 Article 1.8) 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.

1.9      "Committee" means the administrative committee appointed by the Board
         of Directors to manage and administer the Plan in accordance with the
         provisions of 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.

1.10     "Company" means Southwest Gas Corporation and such of its Subsidiaries
         as the Board of Directors may select to become parties to the Plan. The
         term "Company" shall also include any Successor Corporation.

1.11     "Company Contributions" means the amount added, if any, to a
         Participant's Account Balance in accordance with Article 3.2.

1.12     "Deferral(s)" means the amount of Base Annual Salary, Bonus and special
         income, as referred to in Article 3.9, transferred to the Plan
         accounts.

1.13     "Employee" means any full-time employee of Southwest Gas Corporation as
         determined under the personnel policies and practices of Southwest Gas
         Corporation prior to a Change in Control.

1.14     "Executive" means any officer of Southwest Gas Corporation prior to a
         Change in Control.

1.15     "Master Plan Document" means this legal instrument containing the
         provisions of the Plan.

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1.16     "Moody's Rate" means Moody's Seasoned Corporate Bond Rate which is an
         economic indicator consisting of an arithmetic average of yields of
         representative bonds (industrial and AAA, AA and A rated public
         utilities) as of January 1 prior to each Plan Year as published by
         Moody's Investors Service, Inc. (or any successor thereto), or, if such
         index is no longer published, a substantially similar index selected by
         the Board of Directors.

1.17     "Moody's Composite Rate" means the average of the Moody's Rate on
         January 1 for the five (5) years prior to Benefit Distribution.

1.18     "Participant" means any Executive who executes a Plan Agreement or an
         Employee who has been selected to participate in the Plan and who
         executes a Plan Agreement.

1.19     "Plan" means the Executive Deferral Plan of the Company evidenced by
         this Master Plan Document.

1.20     "Plan Agreement" means the form of written agreement which is entered
         into from time to time, by and between the Company and a Participant.

1.21     "Plan Year" means the year beginning on March 1 of each year.

1.22     "Retire" or "Retirement" means the severance from employment with the
         Company on or after attaining age 55, other than by death, disability
         or Termination of Employment.

1.23     "Subsidiary" means any corporation, partnership, or other organization
         which is at least 50% owned by the Company or a Subsidiary of the
         Company.

1.24     "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.

1.25     "Terminates Employment" or "Termination of Employment" means the
         ceasing of employment with the Company, either voluntarily or
         involuntarily, excluding Retirement, disability or death.

1.26     "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.

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

1.28     "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").

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

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

1.31     "Years of Service" means a Participant's Benefit Service as defined in
         the Retirement Plan for Employees of Southwest Gas Corporation, plus
         service with a Successor Corporation which is not taken into account
         for such plan.

                                    ARTICLE 2
                                   ELIGIBILITY

2.1      SELECTION OF PARTICIPANTS. An Executive shall become eligible to
         participate in the Plan as of the effective date of his election by the
         Board of Directors as an officer of the Company (unless the Board of
         Directors determines, at that time, that such Executive will not become
         eligible to participate in the Plan). The Committee in its sole
         discretion may select any other Employee to become eligible to
         participate in the Plan.

2.2      CONTINUED ELIGIBILITY. If a Participant ceases to be an Executive and
         he continues as an Employee, the Committee in its sole discretion will
         determine whether such Employee will continue to be eligible to
         participate in the Plan. Notwithstanding the foregoing and upon the
         occurrence of a Change in Control, a Participant will continue to
         participate in the Plan.

2.3      PARTICIPANT ACCEPTANCE. Once eligible to participate in the Plan, an
         Executive or an Employee has to complete, execute and return to the
         Committee a Plan Agreement to become a Participant in the Plan.
         Continued participation in the Plan is subject to compliance with any
         further conditions as may be established by the Committee.
         Notwithstanding the foregoing and upon the occurrence of a Change in
         Control, no additional conditions regarding continued participation in
         the Plan may be established by the Committee or any Successor
         Corporation.

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                                    ARTICLE 3
                  DEFERRAL COMMITMENT AND COMPANY CONTRIBUTION

3.1      DEFERRALS. A Participant may defer up to 100% of his Base Annual Salary
         and Bonus received during a Plan Year; provided, that such Deferral
         exceeds $2,000 per Plan Year. Notwithstanding the foregoing, no
         election shall be effective to reduce the Base Annual Salary and Bonus
         paid to a Participant for a calendar year to an amount which is less
         than the amount that the Company is required to withhold from such
         Participant's Base Annual Salary and Bonus for the calendar year for
         (a) applicable income and employment taxes (including Federal Insurance
         Contributions Act tax), (b) contributions to any employee benefit plan
         (other than this Plan), and (c) payroll transfers, in place, prior to
         such elections.

3.2      COMPANY MATCHING CONTRIBUTIONS. If a Participant makes a Deferral
         commitment with respect to Base Annual Salary and/or Bonus, the Company
         will contribute an amount equal to 50% of such Deferral, up to a
         maximum of 3% of the Participant's Base Annual Salary, to the
         Participant's Account Balance.

3.3      TIMING OF DEFERRAL ELECTION. Prior to the commencement of each Plan
         Year, a Participant will (a) advise the Committee, in writing, of his
         Base Annual Salary Deferral commitment for the upcoming Plan Year and
         (b) make his Deferral commitment for any Bonus earned during the
         calendar year ending in such Plan Year. If a Participant fails to so
         advise the Committee, through no fault of the Company, he will not be
         permitted to defer any of his Base Annual Salary or Bonus during the
         upcoming Plan Year.

3.4      EXERCISE OF DEFERRAL COMMITMENT. A Participant's Deferral commitment
         will be exercised on a per pay period basis for the portion of his Base
         Annual Salary that is deferred. The exercise of a Participant's
         Deferral commitment with respect to his Bonus will occur at the time
         the Bonus is paid.

3.5      ADJUSTMENT TO DEFERRAL COMMITMENT. The Committee reserves the right to
         adjust any Participant's Deferral commitment during a Plan Year to
         ensure that a Participant's actual Deferral does not exceed the maximum
         allowable amount.

3.6      DEFERRAL ELECTIONS BY NEW PARTICIPANTS. In the event an Executive or an
         Employee becomes a Participant in the Plan during a Plan Year, such
         Participant may defer up to 100% of the remaining portion of his Base
         Annual Salary for the current Plan Year. Such Participant must make his
         Deferral commitment by advising the Committee, in writing, at the time
         he elects to become a Participant in the Plan.

3.7      DEFERRAL COMMITMENT DEFAULT. In the event a Participant defaults on his
         Base Annual Salary Deferral commitment, the Participant will not be
         allowed to make any further Deferrals during the current Plan Year and
         may not make any Deferrals for

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         the subsequent Plan Year. In the event a Participant defaults on his
         Bonus Deferral commitment for a particular Plan Year, the Participant
         will not be able to defer any of his Bonus for that Plan Year or the
         subsequent Plan Year.

3.8      WAIVER OF DEFERRAL COMMITMENT DEFAULT. The Committee may waive for good
         cause the default penalty specified in Article 3.7 upon the request of
         the Participant.

3.9      DEFERRAL OF SPECIAL INCOME. A Participant who is entitled to receive
         cash (a) from the cancellation of stock options granted under the 1996
         Stock Incentive Plan as a result of a Change in Control, (b) from the
         cancellation of outstanding performance shares issued pursuant to the
         Management Incentive Plan as a result of a Change in Control, or (c)
         under an employment, severance or special pay arrangement payable on
         account of termination of employment resulting from a Change in
         Control, may elect to defer receipt of all or a portion of such income;
         provided that such election is filed with the Committee at least six
         (6) months prior to the date such income would otherwise have become
         payable to the Participant. If the Participant makes such an election,
         such income shall not be paid to the Participant but rather shall be
         treated as a Deferral and added to the Participant's Account Balance as
         of the date such income would otherwise have been paid to the
         Participant. In addition, for such election to be effective with
         respect to the deferral of income resulting from the cancellation of an
         option, the Participant must agree in writing that such option shall
         not be exercised at all after the date of the election. Notwithstanding
         the foregoing, a Participant's election to defer income resulting from
         cancellation of an option shall terminate and the option may be
         exercised in accordance with its terms without regard to the election
         if the option would otherwise expire prior to cancellation (for
         example, because of the Participant's termination of employment) or if
         the cancellation does not occur.

                                    ARTICLE 4
                         INTEREST, CREDITING AND VESTING

4.1      INTEREST RATE. A Participant's Account Balance at the start of a Plan
         Year and any Deferrals and Company contributions made during a Plan
         Year will earn, except as provided for in Article 4.2, interest
         annually at 150% of the Moody's Rate. Interest will be credited to a
         Participant's account for Deferrals and Company contributions made
         during the Plan Year, as if all Deferrals and contributions were made
         on the first day of the Plan Year.

4.2      ADJUSTMENT TO INTEREST RATE. If a Participant Terminates Employment
         prior to completing five (5) Years of Service with the Company,
         interest credited for all Deferrals and vested Company contributions to
         a Participant's Account Balance will be adjusted based on the Moody's
         Rate during the period he participated in the Plan.

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4.3      VESTING OF COMPANY CONTRIBUTIONS. Company contributions and interest
         earned on such contributions will vest to a Participant at the rate of
         20% per Year of Service and will vest completely once a Participant has
         five (5) Years of Service with the Company.

4.4      INTEREST DURING POSTPONEMENT OF BENEFIT DISTRIBUTION. In the event a
         Participant is allowed to postpone Benefit Distribution under the Plan,
         his Account Balance will earn interest annually under the provisions of
         Article 4.1, until Benefit Distribution.

                                    ARTICLE 5
                              PLAN BENEFIT PAYMENTS

5.1      LUMP-SUM PAYMENT. A Participant's Account Balance will be paid to the
         Participant in a lump-sum payment at the time of Benefit Distribution,
         unless the Participant qualifies to receive benefit payments over a
         specific benefit payment period.

5.2      INTEREST PRIOR TO BENEFIT DISTRIBUTION. A Participant's Account Balance
         will earn interest under the provisions of Article 4.1 or, if
         applicable, Article 4.2 until the time of Benefit Distribution.

5.3      BENEFIT PAYMENT PERIODS. If a Participant is entitled to receive Plan
         benefit payments over a specific benefit payment period, his Account
         Balance at the commencement of Benefit Distribution will be credited
         with an amount equal to the interest such balance would have earned
         assuming distribution in equal monthly installments over the specific
         benefit payment period, at a specified interest rate, thereby creating
         a Benefit Account Balance. The Benefit Account Balance will then be
         paid to the Participant in equal monthly installments over the specific
         benefit payment period.

5.4      PAYMENT PRIOR TO BENEFIT DISTRIBUTION. If there shall be a final
         determination by the Internal Revenue Service or a court of competent
         jurisdiction that the election by a Participant to defer the payment of
         any amount in accordance with the terms of this Plan was not effective
         to defer the taxation of such amount, then the Participant shall be
         entitled to receive a distribution of the amount determined to be
         taxable and the Participant's Account Balance shall be reduced
         accordingly.

                                    ARTICLE 6
                   RETIREMENT AND TERMINATION BENEFIT PAYMENTS

6.1      BENEFIT PAYMENT PERIODS; ELECTIONS. A Participant who Retires or
         Terminates Employment with more than five (5) Years of Service
         qualifies to receive his Account Balance over a period of 120, 180 or
         240 months. The Participant shall

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         elect the payment period; provided that written notice of such election
         is filed with the Committee at least one (1) year prior to his
         Retirement or Termination of Employment. If a Participant fails to make
         such election prior to the time specified, the payment period will be
         240 months.

6.2      BENEFIT PAYMENT DEFERRAL; ELECTIONS. A Participant who Retires or
         Terminates Employment with more than five (5) Years of Service, may
         elect to defer his Benefit Distribution for up to five (5) years from
         the date on which he Retires or Terminates Employment; provided that
         written notice of such election is filed with the Committee at least
         one (1) year prior to his Retirement or Termination of Employment. If a
         Participant makes an election under this Article 6.2, the Participant's
         Account Balance shall be paid in one of the optional forms of
         distribution set forth in Article 6.1 as elected by the Participant.

6.3      CHANGING ELECTIONS. A Participant who has made an election under this
         Article may subsequently revoke such election and make another election
         under this Article by providing written notice to the Committee;
         provided, however, that only the last such election or revocation in
         effect on the date which is one (1) year prior to the date on which the
         Participant Retires or Terminates Employment shall be effective.
         Notwithstanding the foregoing, if a Participant Terminates Employment
         or Retires as a result of a Change in Control or within one year after
         March 1, 1999, the date of amendment and restatement of this Plan, the
         foregoing provisions of this Article 6 shall be applied by substituting
         "six (6) months" for "one (1) year."

6.4      INTEREST ON BENEFIT PAYMENTS. The interest rate used to calculate the
         amount that will be credited to a Participant's Account Balance, to
         determine his Benefit Account Balance under the provisions of Article
         5.3, will be 150% of the Moody's Composite Rate.

                                    ARTICLE 7
                    PRE-RETIREMENT SURVIVOR BENEFIT PAYMENTS

7.1      BENEFIT PAYMENTS. Notwithstanding any elections made pursuant to
         Article 6, if a Participant dies while he is an employee of the
         Company, his Account Balance will be paid to his Beneficiary in equal
         monthly installments over the 180 month survivor benefit payment
         period.

7.2      INTEREST ON BENEFIT PAYMENTS. The interest rate used to determine the
         amount that will be credited to a Participant's Account Balance, to
         determine his Benefit Account Balance under the provisions of Article
         5.3 following the Participant's death, will be 150% of the Moody's
         Composite Rate.

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                                    ARTICLE 8
                    POST-RETIREMENT SURVIVOR BENEFIT PAYMENTS

8.1      BENEFIT PAYMENTS. If a Participant dies after the commencement of
         Retirement, Termination of Employment or disability benefit payments
         under Articles 6 or 9 but prior to such benefits having been paid in
         full, the Participant's benefit payments will continue to be paid to
         the Participant's Beneficiary through the end of the originally awarded
         benefit payment period, except as provided for in Article 10.7.

8.2      DELAYED BENEFIT PAYMENTS. If a Participant who has elected to postpone
         Benefit Distribution under the provisions of Article 6, dies after he
         Retires or Terminates Employment but prior to the commencement of
         benefit payments, payment of benefits to his Beneficiary will be made
         consistent with such elections.

                                    ARTICLE 9
                           DISABILITY BENEFIT PAYMENTS

9.1      DISABILITY DETERMINATION. A Participant shall be considered disabled if
         he qualifies for a disability benefit under the Company's group
         long-term disability plan. In the event a Participant does not qualify
         for benefits under the group long-term disability plan, the Committee
         may determine that a Participant is disabled under the provisions of
         the Plan.

9.2      VESTING OF COMPANY CONTRIBUTIONS. Notwithstanding the provisions of
         Article 4.3, Company contributions and interest earned on such
         contributions will be fully vested to the Participant at the time he is
         determined to be disabled under this Article.

9.3      BENEFIT PAYMENTS DURING FIRST FIVE (5) YEARS OF SERVICE. If a
         Participant is disabled within the first five (5) Years of Service with
         the Company, he will receive his Account Balance in a lump sum payment
         at Benefit Distribution.

9.4      BENEFIT PAYMENTS AFTER FIVE (5) YEARS OF SERVICE. Notwithstanding any
         elections made pursuant to Article 6, if a Participant is disabled
         after five (5) Years of Service with the Company, his Account Balance
         will be paid to him in equal monthly installments over the 180 month
         disability payment period.

9.5      INTEREST ON BENEFIT PAYMENTS. If a Participant qualifies to receive his
         Account Balance over the disability benefit payment period, the
         interest rate used to calculate the amount that will be credited to a
         Participant's Account Balance, to determine his Benefit Account Balance
         under the provisions of Article 5.3, will be 150% of the Moody's
         Composite Rate.

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                                   ARTICLE 10
                                  BENEFICIARIES

10.1     DESIGNATION OF BENEFICIARIES. A Participant shall have the right to
         designate any person as his Beneficiary to whom benefits under this
         Plan shall be paid in the event of the Participant's death prior to the
         total distribution of his Benefit Account Balance under the Plan. If
         greater than 50% of the Benefit Account Balance is designated to a
         Beneficiary other than the Participant's spouse, such Beneficiary
         designation must be consented to by the Participant's spouse. Each
         Beneficiary designation must be in written form prescribed by the
         Committee and will be effective only when filed with the Committee
         during the Participant's lifetime.

10.2     CHANGING BENEFICIARY DESIGNATION. A Participant shall have the right to
         change the Beneficiary designation, subject to spousal consent under
         the provisions of Article 10.1, without the consent of any designated
         Beneficiary by filing a new Beneficiary designation with the Committee.
         The filing of a new Beneficiary designation form will cancel all
         Beneficiary designations previously filed.

10.3     ACKNOWLEDGMENT. The Committee shall acknowledge, in writing, receipt of
         each Beneficiary designation form.

10.4     DISCHARGE OF COMPANY OBLIGATION. The Committee shall be entitled to
         rely on the Beneficiary designation last filed by the Participant prior
         to his death. Any payment made in accordance with such designation
         shall fully discharge the Company from all further obligations with
         respect to the amount of such payments.

10.5     MINOR OR INCOMPETENT BENEFICIARIES. If a Beneficiary entitled to
         receive benefits under the Plan is a minor or a person declared
         incompetent, the Committee may direct payment of such benefits to the
         guardian or legal representative of such minor or incompetent person.
         The Committee may require proof of incompetency, minority or
         guardianship as it may deem appropriate prior to distribution of any
         Plan benefits. Such distribution shall completely discharge the
         Committee and the Company from all liability with respect to such
         payments.

10.6     EFFECT OF NO BENEFICIARY DESIGNATION. If no Beneficiary designation is
         in effect at the time of the Participant's death, or if the named
         Beneficiary predeceased the Participant, then the Beneficiary shall be:
         (a) the surviving spouse; (b) if there is no surviving spouse, then his
         issue per stirpes; or (c) if no surviving spouse or issue, then his
         estate.

10.7     PAYMENT TO CONTINGENT BENEFICIARY. If a Beneficiary receiving benefit
         payments under the provisions of the Plan dies prior to the completion
         of the benefit payment period, the present value of the remaining
         benefit payments will be paid, in a lump sum amount, to the contingent
         Beneficiary designated by the Participant under the provisions of
         Article 10.1. If the Participant has failed to designate a contingent

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         Beneficiary, the present value of the remaining benefit payments will
         be paid, in a lump sum amount, to the Beneficiary's estate. The present
         value of the remaining benefit payments will be calculated using the
         same methodology, including the same interest rate, as was used to
         calculate the Participant's annuity payment calculation, under Article
         5.3.

                                   ARTICLE 11
                                LEAVE OF ABSENCE

11.1     CONTINUATION OF DEFERRAL COMMITMENT. If a Participant is authorized by
         the Company for any reason to take a paid leave of absence, the
         Participant's Deferral commitment shall remain in full force and
         effect.

11.2     SUSPENSION OF DEFERRAL COMMITMENT. If a Participant is authorized by
         the Company for any reason to take an unpaid leave of absence, the
         Participant's Deferral commitment shall be suspended until the leave of
         absence ends and the Participant's employment resumes.

                                   ARTICLE 12
                                     GENERAL

12.1     PAYMENT OBLIGATION. 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."

12.2     LIMITATION ON PAYMENT OBLIGATION. The Company shall have no obligation
         under the Plan to a Participant or a Participant's Beneficiary, except
         as provided in this Master Plan Document.

12.3     FURNISHING INFORMATION. The Participant must cooperate with the
         Committee in furnishing all information requested by the Company to
         facilitate the payment of his Benefit Account Balance. Such information
         may include the results of a physical examination if any is required
         for participation in the Plan.

12.4     UNSECURED GENERAL CREDITOR. Participants and their Beneficiaries,
         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

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         unfunded and unsecured promise of the Company to pay money in the
         future, and the rights of the Participants and Beneficiaries 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 Article 14.1) be unfunded for purposes of the Code and for the
         purposes of Title I of the Employee Retirement Income Security Act of
         1974, as amended ("ERISA").

12.5     WITHHOLDING. There shall be deducted from each payment made under the
         Plan or other compensation payable to the Participant (or Beneficiary)
         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 amount of said taxes.

                                   ARTICLE 13
                      NO GUARANTEE OF CONTINUING EMPLOYMENT

13.1     FUTURE EMPLOYMENT. The terms and conditions of this Plan shall not be
         deemed to constitute a contract of employment between the Company and a
         Participant. Moreover, nothing in the Plan shall be deemed to give a
         Participant the right to be retained in the service of the Company or
         to interfere with the right of the Company to discipline or discharge
         the Participant at any time.

                                   ARTICLE 14
                                     TRUSTS

14.1     TRUSTS. 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 Agreements. 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 of Directors and shall have such powers as provided in the
         Trust Agreement. The Committee or the Board of Directors 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 of Directors 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 Article 14.1 will cease with a
         Change in Control.

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                                   ARTICLE 15
               TERMINATION, AMENDMENT OR MODIFICATION OF THE PLAN

15.1     PLAN AMENDMENT AND TERMINATION. The Board of Directors may, at any
         time, without notice, amend or modify the Plan in whole or in part;
         provided, however, that (a) no amendment or modification shall be
         effective to decrease or restrict (i) the amount of interest to be
         credited to a Participant's Account Balance under the provisions of the
         Plan, (ii) the benefits the Participant qualifies for or may elect to
         receive under the provisions of the Plan, or (iii) benefit payments to
         Participants or Beneficiaries once such payments have commenced, and
         (b) effective March 1, 1999, no amendment or modification of this
         Article 15, Article 17, or Article 18 of the Plan shall be effective.

15.2     PLAN TERMINATION. The Board of Directors shall not terminate the Plan
         until all accrued benefits have been paid in full under the provisions
         of the Plan to the Participants and Beneficiaries.

15.3     PARTIAL PLAN TERMINATION. Except for the Participants' ability to defer
         special income under the provisions of Article 3.9, the Board of
         Directors may partially terminate the Plan by instructing the Committee
         not to accept any additional Deferral commitments. In the event of a
         partial termination, the remaining provisions of the Plan shall
         continue to operate and be effective for all Participants in the Plan,
         as of the date of such partial termination.

15.4     CHANGE OF CONTROL. In the event of a hostile or non-negotiated Change
         of Control of the Company, the benefits of this Plan will become 100%
         vested for all Participants and the interest credited to a
         Participant's Account Balance under any provision of this Plan will be
         adjusted, retroactively to the date an individual became a Participant
         and prospectively thereafter, to 200% of the Moody's Rate.

                                   ARTICLE 16
                     RESTRICTIONS ON ALIENATION OF BENEFITS

16.1     ALIENATION OF BENEFITS. 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.

                                   ARTICLE 17
                           ADMINISTRATION OF THE PLAN

17.1     COMMITTEE DUTIES. Except as otherwise provided in this Article 17, and
         subject to Article 18, the general administration of the Plan, as well
         as construction and interpretation thereof, shall be vested in the
         Committee. Members of the Committee

                                       13
<PAGE>   15

         may be Participants under the Plan. 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.

17.2     ADMINISTRATION AFTER A CHANGE IN CONTROL. 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 Article 18. The Third Party Fiduciary may not be terminated
         by the Company without the consent of 50% of the Participants in the
         Plan.

17.3     AGENTS. 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.

17.4     BINDING EFFECT OF DECISIONS. 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 Article 17.2) and the rules and regulations
         promulgated hereunder shall be final and conclusive and binding upon
         all persons having any interest in the Plan.

17.5     INDEMNITY BY COMPANY. 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.

                                       14
<PAGE>   16

17.6     EMPLOYER INFORMATION. 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
         Employment, and such other pertinent facts as the Committee or the
         Third Party Fiduciary may require.

17.7     MANNER AND TIMING OF BENEFIT PAYMENTS. The Committee or the Third Party
         Fiduciary, as the case may be, may alter, at or after Benefit
         Distribution, the manner and time of payments to be made to a
         Participant or Beneficiary from that set forth herein, if requested to
         do so by such Participant or Beneficiary to meet existing financial
         hardships, which the Committee or the Third Party Fiduciary, as the
         case may be, determine are the same as or similar in nature to those
         identified in Section 1.401(k)-1(d)(2)(iv) of the federal treasury
         regulations.

                                   ARTICLE 18
                                CLAIMS PROCEDURE

18.1     PRESENTATION OF CLAIMS. Any Participant or Beneficiary of a deceased
         Participant (such Participant or Beneficiary 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.

18.2     NOTIFICATION OF DECISION. 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 Article 18.3.

18.3     REVIEW OF A DENIED CLAIM. Within 60 days after receiving a notice from
         the Committee that a claim has been denied, in whole or in part, a
         Claimant (or

                                       15
<PAGE>   17

         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.

18.4     DECISION ON REVIEW. 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.

18.5     LEGAL ACTION. A Claimant's compliance with the foregoing provisions of
         this Article 18 is a mandatory prerequisite to a Claimant's right to
         commence any legal action with respect to any claim for benefits under
         the Plan.

                                   ARTICLE 19
                                  MISCELLANEOUS

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

                                    SOUTHWEST GAS CORPORATION
                                    Executive Deferral Plan
                                    Administrative 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

19.2     ASSIGNMENT. 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.

                                       16
<PAGE>   18

19.3     GOVERNING LAWS. Except to the extent that federal law applies, the Plan
         shall be governed by and construed under the laws of the State of
         Nevada.

19.4     HEADINGS. Headings in this Master Plan Document are inserted for
         convenience of reference only. Any conflict between such headings and
         the text shall be resolved in favor of the text.

19.5     GENDER AND NUMBER. Masculine pronouns wherever used shall include
         feminine pronouns and when the context dictates, the singular shall
         include the plural.

19.6     EFFECT OF ILLEGALITY OR INVALIDITY. 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.

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

                                         SOUTHWEST GAS CORPORATION

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

                                       17<PAGE>   1

                                                                   EXHIBIT 10.14

                              MASTER PLAN DOCUMENT

                            SOUTHWEST GAS CORPORATION

                             DIRECTORS DEFERRAL PLAN

                           Effective October 29, 1992
                         Amended Effective March 5, 1996
                  Amended and Restated Effective March 1, 1999

<PAGE>   2

                              MASTER PLAN DOCUMENT
                SOUTHWEST GAS CORPORATION DIRECTORS DEFERRAL PLAN

                                     PURPOSE

The purpose of this Plan is to provide specified benefits to Directors of
SOUTHWEST GAS CORPORATION.

                                    ARTICLE 1
                                   DEFINITIONS

For purposes hereof, unless otherwise clearly apparent from the context, the
words and phrases listed below shall be defined as follows:

1.1      "Account Balance" means a Participant's individual fund comprised of
         Deferrals, rollovers contributions from the PriMerit Bank, Federal
         Savings Bank directors deferral plan and interest earnings credited
         thereon up to the time of Benefit Distribution.

1.2      "Beneficiary" means the person or persons, or the estate of a
         Participant, named to receive any benefits under the Plan upon the
         death of a Participant.

1.3      "Benefit Account Balance" shall have the meaning set forth in Article
         5.3.

1.4      "Benefit Distribution" means the date benefits under the Plan commence
         or are paid in full to a Participant, or because of his death, to his
         Beneficiary, which will occur within 90 days of notification to the
         Company of the event that gives rise to such distribution.

1.5      "Board Fees" means the compensation received by a Director for serving
         on the Board of Directors of Southwest Gas Corporation and the
         committees of the board.

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

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

         (a)      Any "person" (as the term is used in Section 13 and 14(d)(2)
                  of the Securities Exchange Act of 1934 ("Exchange Act"))
                  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

                                       1
<PAGE>   3

                  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 Article 1.8) 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.

1.8      "Committee" means the administrative committee appointed by the Board
         of Directors to manage and administer the Plan in accordance with the
         provisions of 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.

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

1.10     "Deferral(s)" means the amount of Board Fees and special income, as
         referred to in Article 3.8, transferred to the Plan accounts.

1.11     "Director" means any person on the board of directors of Southwest Gas
         Corporation prior to a Change in Control.

1.12     "Master Plan Document" means this legal instrument containing the
         provisions of the Plan.

1.13     "Moody's Rate" means Moody's Seasoned Corporate Bond Rate which is an
         economic indicator consisting of an arithmetic average of yields of
         representative bonds (industrial and AAA, AA and A rated public
         utilities) as of January 1 prior to each Plan Year as published by
         Moody's Investors Service, Inc. (or any successor thereto), or, if such
         index is no longer published, a substantially similar index selected by
         the Board of Directors.

1.14     "Moody's Composite Rate" means the average of the Moody's Rate on
         January 1 for the five years prior to Benefit Distribution.

1.15     "Participant"  means any Director who executes a Plan Agreement.

1.16     "Plan" means the Director Deferral Plan of the Company evidenced by
         this Master Plan Document.

1.17     "Plan Agreement" means the form of written agreement which is entered
         into from time to time, by and between the Company and a Participant.

1.18     "Plan Year" means the year beginning on March 15 of each year.

1.19     "Retire" or "Retirement" means the cessation of service on the Board of
         Directors

                                       2
<PAGE>   4

         of the Company after attaining five Years of Service, other than by
         death, disability or Termination of Service.

1.20     "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.

1.21     "Subsidiaries" means any corporation, partnership, or other
         organization which is at least 50 percent owned by the Company or a
         Subsidiary of the Company.

1.22     "Terminates Service" or "Termination of Service" means the cessation of
         service on the Board of Directors of the Company, either voluntarily or
         involuntarily, excluding Retirement, disability or death.

1.23     "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.

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

1.25     "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").

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

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

1.28     "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.

                                    ARTICLE 2
                                   ELIGIBILITY

2.1      A Director shall become eligible to participate in the Plan as of the
         effective date of his election as a Director.

2.2      Once eligible to participate in the Plan, a Director has to complete,
         execute and

                                       3
<PAGE>   5

         return to the Committee a Plan Agreement to become a Participant in the
         Plan. Continued participation in the Plan is subject to compliance with
         any further conditions as may be established by the Committee.

                                    ARTICLE 3
                               DEFERRAL COMMITMENT

3.1      A Participant may defer up to 100 percent of his Board Fees received
         during a Plan Year; provided, that such Deferral exceeds $2,000 per
         Plan Year.

3.2      Prior to the commencement of each Plan Year, a Participant will advise
         the Committee, in writing, of his deferral commitment for the upcoming
         Plan Year. If a Participant fails to so advise the Committee, through
         no fault of the Company, he will not be permitted to defer any of his
         Board Fees during the upcoming Plan Year.

3.3      A Participant's Deferral commitment will be exercised on a per pay
         period basis.

3.4      In the event a Director becomes a Participant in the Plan during a Plan
         Year, such Participant may defer up to 100 percent of the remaining
         portion of his Board Fees for the Plan Year. Such Participant must make
         his Deferral commitment by advising the Committee, in writing, at the
         time he elects to become a Participant in the Plan.

3.5      In the event a Participant defaults on his Deferral commitment, the
         Participant will not be allowed to make any further Deferrals during
         the current Plan Year and may not make any Deferrals for the subsequent
         Plan Year.

3.6      The Committee may waive for good cause the default penalty specified in
         Article 3.5 upon the request of the Participant.

3.7      The Plan will accept rollover contributions for Participants from the
         PriMerit Bank, Federal Savings Bank directors deferral plan.

3.8      A Participant who is entitled to receive cash from the cancellation of
         stock options granted under the 1996 Stock Incentive Plan as a result
         of a Change in Control may elect to defer receipt of all or a portion
         of such income; provided that such election is filed with the Committee
         at least six (6) months prior to the date such income would otherwise
         have become payable to the Participant. If the Participant makes such
         an election, such income shall not be paid to the Participant but
         rather shall be treated as a Deferral and added to the Participant's
         Account Balance as of the date such income would otherwise have been
         paid to the Participant. In addition, for such election to be
         effective, the Participant must agree in writing that such option shall
         not be exercised at all after the date of the election. Notwithstanding
         the foregoing, a Participant's election to defer income resulting from
         cancellation of an option shall terminate and the option may be
         exercised in accordance with its terms without regard to the election
         if the option would otherwise expire prior to cancellation (for
         example, because of the Participant's Termination of Service) or

                                       4
<PAGE>   6

         if the agreement setting forth the terms of the Change in Control is
         terminated prior to the closing date set forth in such agreement.

                                    ARTICLE 4
                         INTEREST, CREDITING AND VESTING

4.1      A Participant's Account Balance at the start of a Plan Year and any
         Deferrals made during a Plan Year and rollover contributions from the
         PriMerit Bank, Federal Savings Bank directors deferral plan will earn
         interest annually at 150 percent of the Moody's Rate. Interest will be
         credited to a Participant's account for Deferrals made during the Plan
         Year, as if all Deferrals were made on the first day of the Plan Year.
         Interest will be credited to a Participant's account for rollover
         contributions, from the date such contributions are accepted by the
         Plan.

                                    ARTICLE 5
                              PLAN BENEFIT PAYMENTS

5.1      A Participant's Account Balance will be paid to the Participant as
         provided for under the provisions of the Plan.

5.2      A Participant's Account Balance will earn interest under the provisions
         of Article 4.1 until the time of Benefit Distribution.

5.3      If a Participant is entitled to receive Plan benefit payments over a
         specific benefit payment period, his Account Balance at the
         commencement of Benefit Distribution will be credited with an amount
         equal to the interest such balance would have earned assuming
         distribution in equal monthly installments over the specific benefit
         payment period, at a specified interest rate, thereby creating a
         Benefit Account Balance. The Benefit Account Balance will then be paid
         to the Participant in equal monthly installments over the specific
         benefit payment period.

5.4      If there shall be a final determination by the Internal Revenue Service
         or a court of competent jurisdiction that the election by a Participant
         to defer the payment of any amount in accordance with the terms of this
         Plan was not effective to defer the taxation of such amount, then the
         Participant shall be entitled to receive a distribution of the amount
         determined to be taxable and the Participant's Account Balance shall be
         reduced accordingly.

                                       5
<PAGE>   7

                                    ARTICLE 6
                   RETIREMENT AND TERMINATION BENEFIT PAYMENTS

6.1      A Participant who Retires or Terminates Service qualifies to receive
         his Account Balance over a period of 60, 120, 180 or 240 months. The
         Participant shall elect the payment period; provided that written
         notice of such election is filed with the Committee at least one (1)
         year prior to his Retirement or Termination of Employment. If a
         Participant fails to make such election prior to the time specified,
         the payment period will be 240 months.

6.2      A Participant who Retires or Terminates Service may elect to defer his
         Benefit Distribution for up to five (5) years from the date on which he
         Retires or Terminates Service; provided that written notice of such
         election is filed with the Committee at least one (1) year prior to his
         Retirement or Termination of Service. If a Participant makes an
         election under this Article 6.2, the Participant's Account Balance
         shall be paid in one of the optional forms of distribution set forth in
         Article 6.1, as elected by the Participant.

6.3      A Participant who has made an election under this Article may
         subsequently revoke such election and make another election under this
         Article by providing written notice to the Committee; provided,
         however, that only the last such election or revocation in effect on
         the date which is one (1) year prior to the date on which the
         Participant Retires or Terminates Service shall be effective.
         Notwithstanding the foregoing, if a Participant Retires or Terminates
         Service as a result of a Change in Control or within one (1) year after
         March 1, 1999, the date of amendment and restatement of this Plan, the
         foregoing provisions of this Article 6 shall be applied by substituting
         "six (6) months" for "one (1) year."

6.4      The interest rate used to calculate the amount that will be credited to
         a Participant's Account Balance, to determine his Benefit Account
         Balance under the provisions of Article 5.3, will be 150 percent of the
         Moody's Composite Rate.

                                    ARTICLE 7
                    PRE-RETIREMENT SURVIVOR BENEFIT PAYMENTS

7.1      Notwithstanding any elections made pursuant to Article 6, if a
         Participant dies while he is on the Board of Directors, his Account
         Balance will be paid to his Beneficiary in equal monthly installments
         over the 180 month survivor benefit payment period.

7.2      The interest rate used to determine the amount that will be credited to
         a Participant's Account Balance, to determine his Benefit Account
         Balance under the provisions of Article 5.3 following the Participant's
         death, will be 150% of the Moody's Composite Rate.

                                       6
<PAGE>   8

                                    ARTICLE 8
                    POST-RETIREMENT SURVIVOR BENEFIT PAYMENTS

8.1      If a Participant dies after the commencement of benefit payments under
         Articles 6 or 9 but prior to such benefits having been paid in full,
         the Participant's benefit payments will continue to be paid to the
         Participant's Beneficiary through the end of the originally awarded
         benefit payment period, except as provided for in Article 10.7.

8.2      If a Participant who has elected to postpone Benefit Distribution under
         the provisions of Article 6, dies after he Retires or Terminates
         Service but prior to the commencement of benefit payments, payment of
         benefits to his Beneficiary will be made consistent with such
         elections.

                                    ARTICLE 9
                           DISABILITY BENEFIT PAYMENTS

9.1      The Committee will, in its sole discretion, determine whether a
         Participant is disabled under the provisions of the Plan.

9.2      If a Participant is disabled within the first five Years of Service
         with the Company, he will receive his Account Balance in a lump sum
         payment at Benefit Distribution.

9.3      Notwithstanding any elections made pursuant to Article 6, if a
         Participant is disabled after five Years of Service with the Company,
         his Account Balance will be paid to him in equal monthly installments
         over the 180-month disability benefit payment period.

9.4      If a Participant qualifies to receive his Account Balance over the
         disability benefit payment period, the interest rate used to calculate
         the amount that will be credited to a Participant's Account Balance, to
         determine his Benefit Account Balance under the provisions of Article
         5.3, will be 150 percent of the Moody's Composite Rate.

                                   ARTICLE 10
                                  BENEFICIARIES

10.1     A Participant shall have the right to designate any person as his
         Beneficiary to whom benefits under this Plan shall be paid in the event
         of the Participant's death prior to the total distribution of his
         Benefit Account Balance under the Plan. If greater than 50 percent of
         the Benefit Account Balance is designated to a Beneficiary other than
         the Participant's spouse, such Beneficiary designation must be
         consented to by the Participant's spouse. Each Beneficiary designation
         must be in written form prescribed by the Committee and will be
         effective only when filed with the Committee during the Participant's
         lifetime.

10.2     A Participant shall have the right to change the Beneficiary
         designation, subject to

                                       7
<PAGE>   9

         spousal consent under the provisions of Article 10.1, without the
         consent of any designated Beneficiary by filing a new Beneficiary
         designation with the Committee. The filing of a new Beneficiary
         designation form will cancel all Beneficiary designations previously
         filed.

10.3     The Committee shall acknowledge, in writing, receipt of each
         Beneficiary designation form.

10.4     The Committee shall be entitled to rely on the Beneficiary designation
         last filed by the Participant prior to his death. Any payment made in
         accordance with such designation shall fully discharge the Company from
         all further obligations with respect to the amount of such payments.

10.5     If a Beneficiary entitled to receive benefits under the Plan is a minor
         or a person declared incompetent, the Committee may direct payment of
         such benefits to the guardian or legal representative of such minor or
         incompetent person. The Committee may require proof of incompetency,
         minority or guardianship as it may deem appropriate prior to
         distribution of any Plan benefits. Such distribution shall completely
         discharge the Committee and the Company from all liability with respect
         to such payments.

10.6     If no Beneficiary designation is in effect at the time of the
         Participant's death, or if the named Beneficiary predeceased the
         Participant, then the Beneficiary shall be: (1) the surviving spouse;
         (2) if there is no surviving spouse, then his issue per stirpes; or (3)
         if no surviving spouse or issue, then his estate.

10.7     If a Beneficiary receiving benefit payments under the provisions of the
         Plan dies prior to the completion of the benefit payment period, the
         present value of the remaining benefit payments will be paid, in a lump
         sum amount, to the contingent Beneficiary designated by the Participant
         under the provisions of Article 10.1. If the Participant has failed to
         designate a contingent Beneficiary, the present value of the remaining
         benefit payments will be paid, in a lump sum amount, to the
         Beneficiary's estate. The present value of the remaining benefit
         payments will be calculated using the same methodology, including the
         same interest rate, as was used to calculate the Participant's annuity
         payment calculation, under Article 5.3.

                                   ARTICLE 11
                                     GENERAL

11.1     Amounts payable to a Participant shall be paid exclusively 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."

                                       8
<PAGE>   10

11.2     The Company shall have no obligation under the Plan to a Participant or
         a Participant's Beneficiary, except as provided in this Master Plan
         Document.

11.3     The Participant shall cooperate with the Committee in furnishing all
         information requested by the Company to facilitate the payment of his
         Benefit Account Balance. Such information may include the results of a
         physical examination if any is required for participation in the Plan.

11.4     Participants and their Beneficiaries, 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 and Beneficiaries 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 Article 13.1)
         be unfunded for purposes of the Code.

11.5     There shall be deducted from each payment made under the Plan or other
         compensation payable to the Participant (or Beneficiary) 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 amount of said taxes.

                                   ARTICLE 12
                     NO GUARANTEE OF CONTINUING DIRECTORSHIP

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

                                   ARTICLE 13
                                     TRUSTS

13.1     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 Agreements. 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 of Directors and shall have such powers as provided in the
         Trust Agreement. The Committee or the Board of Directors 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 of Directors may

                                       9
<PAGE>   11

         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 Article 13.1 will
         cease with a Change in Control.

                                   ARTICLE 14
               TERMINATION, AMENDMENT OR MODIFICATION OF THE PLAN

14.1     The Board of Directors may at any time, without notice, amend or modify
         the Plan in whole or in part; provided, however, that (i) no amendment
         shall be effective to decrease or restrict (a) the amount of interest
         to be credited under the provisions of the Plan, (b) the benefits the
         Participant qualifies for or may elect to receive under the provisions
         of the Plan, or (c) benefit payments to Participants or Beneficiaries
         once such payments have commenced, and (ii) effective March 1,1999, no
         amendment or modification of this Article 14, Article 16, or Article 17
         of the Plan shall be effective.

14.2     The Board of Directors shall not terminate the Plan until all accrued
         benefits have been paid in full under the provisions of the Plan to the
         Participants and Beneficiaries.

14.3     The Board of Directors may partially terminate the Plan by instructing
         the Committee not to accept any additional Deferral commitments. In the
         event of a partial termination, the remaining provisions of the Plan
         shall continue to operate and be effective for all Participants in the
         Plan, as of the date of such partial termination.

                                   ARTICLE 15
                     RESTRICTIONS ON ALIENATION OF BENEFITS

15.1     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.

                                   ARTICLE 16
                           ADMINISTRATION OF THE PLAN

16.1     Except as otherwise provided in this Article 16, and subject to Article
         17, the general administration of the Plan, as well as construction and
         interpretation thereof, shall be vested in the Committee. Members of
         the Committee may be Participants under the Plan. 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.

                                       10
<PAGE>   12

         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.

16.2     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 Article 17. The
         Third Party Fiduciary may not be terminated by the Company without the
         consent of 50% of the Participants in the Plan.

16.3     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.

16.4     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 Article
         16.2) and the rules and regulations promulgated hereunder shall be
         final and conclusive and binding upon all persons having any interest
         in the Plan.

16.5     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.

16.6     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 Employment, and
         such other pertinent facts as the Committee or the Third Party
         Fiduciary may require.

16.7     The Committee or the Third Party Fiduciary, as the case may be, may
         alter, at or after Benefit Distribution, the manner and time of
         payments to be made to a

                                       11
<PAGE>   13

         Participant or Beneficiary from that set forth herein, if requested to
         do so by such Participant or Beneficiary to meet existing financial
         hardships, which the Committee or the Third Party Fiduciary, as the
         case may be, determine are the same as or similar in nature to those
         identified in Section 1.401(k)-1(d)(2)(iv) of the federal treasury
         regulations.

                                   ARTICLE 17
                                CLAIMS PROCEDURE

17.1     Any Participant or Beneficiary of a deceased Participant (such
         Participant or Beneficiary 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.

17.2     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 Article 17.3.

17.3     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.

17.4     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

                                       12
<PAGE>   14

         was based; and (iii) such other matters as the Third Party Fiduciary
         deems relevant.

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

                                   ARTICLE 18
                                  MISCELLANEOUS

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

                                    SOUTHWEST GAS CORPORATION
                                    Directors Deferral Plan
                                    Administrative 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

18.2     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.

18.3     The Plan shall be governed by and construed under the laws of the State
         of Nevada.

18.4     Headings in this Master Plan Document are inserted for convenience of
         reference only. Any conflict between such headings and the text shall
         be resolved in favor of the text.

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

18.6     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.

                                       13
<PAGE>   15

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

                                          SOUTHWEST GAS CORPORATION

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

                                       14

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