
                                  Exhibit 10.9a

                               [LETTERHEAD OF APS]

                                    AGREEMENT

     THIS  AGREEMENT  is entered into this 13th day of  December,  1999,  in the
State of Arizona by and  between  William L.  Stewart  ("Employee")  and Arizona
Public Service Company ("Company").

                                    RECITALS

1.   Employee  is  employed  by  the  Company  in  the  position  of  President,
     Generation.

2.   Employee is currently eligible to retire from the Company.

3.   Employee's skills, ability and knowledge are highly valued by the Company.

4.   The Company is engaged in the business of generation, construction, and the
     acquisition of electrical  power;  and the transmission and distribution of
     such electrical power ("the Business").

5.   The  Company  has  developed  certain  know-how,   techniques,   and  other
     information  relating to the Business  that it believes to be trade secret,
     confidential,  or  otherwise  proprietary,  and  valuable  to the  Company.
     Employee  will have  access to  certain of such  trade  secrets,  know-how,
     techniques,  and other valuable  company  information,  including  customer
     lists,  product pricing policies,  marketing and distribution  information,
     and other information.  At times, Employee may invent, improve,  develop or
     discover trade secrets,  know-how,  or otherwise  proprietary  confidential
     information, methods or techniques.

                                    AGREEMENT

     NOW THEREFORE,  in consideration of the continued employment of Employee by
the  Company  through  December  31,  2002,  and for  other  good  and  valuable
consideration set forth below, the parties agree as follows:

                                 I. DEFINITIONS

A.   DEFINITIONS.  For the purpose of this  Agreement,  the terms  listed  below
     shall have the following meanings:

     1.   CONFIDENTIAL  INFORMATION  AND MATERIAL shall mean all forms and types
          of business, technical, scientific,  engineering,  financial, economic
          and employment  information belonging to, used by or in the possession
          of the Company relating to its business, customers (including customer
          lists and accounts), vendor information,  systems, procedures, methods
          and techniques, inventions, ideas,

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          discoveries,  improvements,  know-how, production and marketing costs,
          development plans,  computer programs,  forms,  economic and financial
          analyses,  financial  information,  marketing  plans,  employee files,
          trade secrets of every kind and character and/or any other information
          which (a) the Company has taken reasonable measures to keep secret and
          (b) which has independent  actual or potential economic value from not
          being generally known or readily ascertainable to the public or to the
          Company's competitors. Confidential information shall also include any
          information  described  above which the Company  obtains  from another
          party and which the Company  treats as  proprietary  or  designates as
          confidential  information,  whether or not owned or  developed  by the
          Company.

     2.   Customers  shall  mean  persons,  firms,  associations,  partnerships,
          corporations,  or entities to which either the Company or Employee has
          sold, from which the Company or Employee has purchased, or that either
          the Company or Employee has solicited  with the respect to the sale or
          purchase of the following commodities:  electrical power, natural gas,
          coal and emission  allowances  (the Business of the Company) before or
          during the term of Employee's employment with the Company.

                                  II. COVENANTS

A.   SIGNING BONUS.  January 3, 2000,  Employee will receive a one-time  signing
     bonus of $300,000.00.

B.   LINE OF CREDIT.  In addition to the signing  bonus,  the Company  will make
     available  to  Employee  a line of credit in the  amount of  $1,200,000.00,
     which  Employee  may  draw  on  annually  beginning  January  3,  2000,  in
     $400,000.00 annual increments.  Interest will accrue on amounts outstanding
     at the rate of 7.5% annually.  All outstanding  amounts will be due in full
     no later than January 3, 2003,  except as provided in Section II, paragraph
     G, below.

C.   DEFERRED  PAYMENTS.  The  sum of  $400,000.00  per  calendar  year  will be
     deferred for Employee for a three-year  period  beginning in the year 2000.
     Interest  will  be  credited  on the  deferred  amount  at the  rate  of 9%
     annually.  Payment of the deferred amount,  plus interest,  will be made on
     January  3,  2003,  in a lump  sum,  except as  provided  in  Section  II.,
     paragraph G, below.

D.   ADDITIONAL   PAYMENTS.   In  addition,   if  Employee  continues  full-time
     employment  through December 31, 2002,  Employee will receive an additional
     $400,000.00 on January 3, 2003 and January 3, 2004.

E.   PENSION.  Employee's  pension  benefit  will be 80% of  Employee's  average
     monthly  wage on the date of  Employee's  retirement  if  Employee  remains
     working  with the  Company  continuously  in a full-time  capacity  through
     December 31,  2002.  None of the sums  described in  paragraphs A through D
     shall be included in the calculation of Employee's pension benefits.

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F.   CONTINUED  EMPLOYMENT.  Employee  agrees to remain working with the Company
     continuously in a full-time capacity through December 31, 2002.

G.   SEPARATION  FROM  EMPLOYMENT.   Employee's   entitlement  to  the  payments
     described  in this  Section  II.,  paragraphs  B, C, and D,  are  expressly
     conditioned on Employee's continuous, full-time employment with the Company
     through  December 31, 2002. If Employee  separates from employment prior to
     December 31, 2002, for any reason, including death and disability:

     1.   Employee  shall  forfeit  the  benefits   described  in  Section  II.,
          paragraphs B, C, and D.

     2.   Employee  shall not be entitled to borrow any  additional  funds under
          the line of credit and any amounts then outstanding under such line of
          credit,   including  any  accrued  but  unpaid   interest,   shall  be
          immediately due an payable in full, with payment due no later than ten
          (10) days following the date on which Employee's employment terminated
          unless other arrangements satisfactory to the Company have been made.

     3.   All deferred payments,  including interest,  under this Agreement will
          be forfeited by Employee.

     4.   Employee will not receive  additional  payments due on January 3, 2003
          and January 3, 2004.

     5.   Employee's  pension  following his termination of employment  shall be
          calculated  in  accordance  with  the  terms of the  letter  agreement
          between the Company  and  Employee  dated  August 25,  1997,  which is
          incorporated herein by this reference.

H.   TAXES.  All tax liability  arising out of this Agreement will be Employee's
     responsibility.

I.   OWNERSHIP.  Employee  hereby agrees that all  Confidential  Information and
     Material  is  the  property  of  the  Company,  and  that  all  inventions,
     improvements,   ideas,  methods  and  techniques,   know-how,  discoveries,
     customer lists, customer accounts, systems, procedures,  costs, development
     plans,  marketing plans,  computer programs,  forms, economic and financial
     analyses, credit risk assessments,  credit analyses, financial information,
     employee files, trade secrets,  or other work product,  in whole or in part
     conceived  or made by  Employee  during  or after  the  term of  Employee's
     employment  with the Company which are conceived or made through the use of
     any of the  Confidential  Information  and  Material  or any of the Company
     equipment,  facilities,  supplies,  trade secrets or time, or which results
     from  any  work  performed  by  Employee  for  the  Company,  shall  belong
     exclusively  to the Company  and shall be deemed  part of the  Confidential
     Information  and Material for  purposes of this  Agreement,  whether or not
     fixed in a tangible medium of expression.  Without  limiting the foregoing,
     Employee hereby agrees that all copyrightable work product, as listed above
     in this paragraph, shall be deemed to be "works made for hire" and that the
     Company  shall be deemed  the author  thereof  under the US  Copyright  Act
     (Title 12 of the US Code), and if for any reason any of such  copyrightable
     work product is deemed not a work for hire, and, as to all other

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     work product, Employee agrees to execute such documents as are requested by
     the Company to vest all rights in the  Company,  including  all  patentable
     rights;  and to otherwise  cooperate  with the Company in securing all such
     rights.  The Company and Employee  further agree that the Company shall own
     no rights to original works of authorship or other work product  reduced to
     tangible  form by Employee  prior to  Employee's  employment  with Company;
     provided,  that Employee will identify such works (if any) in writing prior
     to  signing  this  Agreement  and  the  listing  will be  attached  to this
     Agreement.

J.   NON-COMPETITION. Employee acknowledges employment with the Company requires
     protection  of the  Company's  interests  upon  termination  because of the
     substantial  investment  in Employee,  the time required to find or train a
     replacement  and  the  entrustment  of  extremely  sensitive   Confidential
     Information  and Materials and Customers to Employee in the  performance of
     Employee's  duties.  During Employee's  employment with Company,  and for a
     period of two years  thereafter,  Employee  shall  not,  without  Company's
     express  written  consent,  directly or  indirectly,  be employed  by, own,
     manage,  operate,  join, control,  participate in or finance the ownership,
     management,  operation  or  control  of,  or be  connected  in any  manner,
     including   consultation,   with  any   firm,   association,   partnership,
     corporation  or other entity that competes with  Company,  its  affiliates,
     successors   and  assigns  in  the  business  of   generating,   acquiring,
     constructing  and/or  distributing  electrical  power in the United States.
     Notwithstanding  the above,  Employee may,  with the prior  approval of the
     Company,  perform services for nuclear  generating  plants. For purposes of
     this paragraph,  "own" and "ownership"  shall not include  ownership of two
     percent (2%) or less of the capital stock of a company whose securities are
     publicly traded.

     Employee acknowledges and agrees that the geographical, time and restricted
     activity limitations in this Agreement are reasonable and properly required
     for the adequate protection of Company's  business,  and are the product of
     negotiations between the parties.  Employee further acknowledges and agrees
     that any breach of this covenant not to compete will result in  irreparable
     damage to Company for which the remedy at law would be inadequate. Employee
     therefore  agrees that, in addition to any other  remedies to which Company
     may be entitled as a matter of law,  Company  shall be entitled to specific
     performance and other equitable relief,  including  temporary and permanent
     injunctive  relief,  to enforce  this  covenant  not to  compete.  Employee
     further  agrees that, if an injunction  issues to enforce this covenant not
     to compete,  the covenant  shall be deemed to run anew with the issuance of
     the injunction so as that Company will have the full time provided herein.

K.   NON-SOLICITATION  OF  EMPLOYEES.  In addition to the  foregoing  covenants,
     Employee  agrees that  during  Employee's  employment  with the Company and
     during the two-year time period immediately  following  Employee's last day
     of employment  with the Company,  Employee will not,  individually or as an
     agent or an employee of or as a consultant  or otherwise on behalf of or in
     conjunction with any person, firm, association,  partnership,  corporation,
     or other  entity,  directly  or  in-directly,  hire,  employ,  solicit,  or
     otherwise  encourage or entice to leave their  employment with the Company,
     any of the  Company's  employees who are or were employed by the Company at
     any time during Employee's

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     employment  with  the  Company  and  the  two-years  immediately  following
     Employee's last day of employment with the Company.

L.   ADHERENCE  TO COMPANY  POLICIES  AND  PROCEDURES,  STATE AND  FEDERAL  LAW.
     Employee acknowledges, understands, and agrees to abide by company policies
     and procedures relating to the creation, handling, non-disclosure,  storage
     and retention of Confidential  Information and Materials.  Employee further
     acknowledges,  understands  and  agrees to abide by State and  Federal  law
     regarding  Confidential  Information  and Material  including  the Economic
     Espionage Act of 1996, 18 U.S.C. sec. 1831-39 and the Arizona Trade Secrets
     Act, A.R.S.ss.44-401.

M.   NON-DISCLOSURE.   Other  than  in  the  performance  of  Employee's  duties
     hereunder, and for the period of Employee's employment with the Company and
     for all times thereafter, Employee agrees to receive and hold in confidence
     and not to disclose or use for the benefit of Employee or any person, firm,
     association,  partnership,  corporation,  or other entity, any Confidential
     Information and Material of the Company without the Company's prior written
     authorization  in  each  particular  case.   Employee  agrees  not  to  use
     Confidential Information and Material of the Company for any purpose except
     on behalf of the Company and as authorized by the Company.

N.   RETURN OF COMPANY  PROPERTY.  Employee further agrees that upon termination
     of employment, or at any time upon the Company's request, and no later than
     the last day of employment  with the Company,  Employee shall  surrender to
     the Company all of the property,  customer lists, notes, manuals,  reports,
     documents,  and other things within  Employee's  possession,  including all
     copies  or  computerized   records   thereof,   which  relate  directly  or
     indirectly, or which contain any Confidential Information and Material.

                               III. ENFORCEABILITY

     Employee  represents  and  warrants  to and  covenants  with the Company as
follows:

A.   The covenants set forth in this Agreement are reasonably  necessary for the
     protection of the interests of the Company;  are reasonable as to duration,
     scope and territory; and are not unreasonably restrictive of Employee.

B.   Employee  acknowledges  that  Confidential  Information  and Material is of
     vital  importance to the Company and its customers.  Employee's  failure to
     protect the Confidential Information and Material according to the terms of
     this  Agreement  may result in  irreparable  harm to the Company,  in which
     instance the  Company's  remedies at law for breach of any of the covenants
     set forth in this Agreement will be inadequate. Accordingly, in addition to
     any other rights or remedies  that the Company may have,  the Company shall
     be entitled to injunctive relief.

     It is  agreed by  Employee  and the  Company  that if any  portions  of the
     restrictions  contained  in Section II or III are held to be  unreasonable,
     arbitrary,  or too broad to be enforceable,  then the restrictions shall be
     deemed to have been modified to be only so broad as to be enforceable.  The
     parties agree that if any court of competent jurisdiction determines the

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     specified period, the specified  territory or the restricted activity to be
     unreasonable,   arbitrary  or  too  broad  to  be  enforceable,  then  such
     unenforceable covenants shall be modified to give the maximum effect to the
     Company as allowed by law.  The court  shall have the  authority  to reform
     this Agreement to make the restrictions reasonable and enforceable.

                                  IV. Entirety

     This Agreement  embodies the entire agreement of the parties respecting the
matters  within its scope and may be modified  only in writing.  This  Agreement
shall  amend the  provisions  of the prior  agreements  between  the Company and
Employee  only  to the  extent  set  forth  herein  and the  provisions  of such
agreements not amended hereby shall remain in full force and effect. In addition
to any benefits  provided  under this  Agreement,  Employee shall be entitled to
benefits  under any  employee  benefit  plan  maintained  by the  Company  or an
affiliate  or under any  agreement  between  the  Company  or an  affiliate  and
Employee  in  accordance  with the terms of such  employee  benefit  programs or
agreements, except as otherwise amended by this Agreement.

                                 V. Severability

     If, for any reason,  any provision of this Agreement shall be determined by
a court of competent  jurisdiction  to be invalid,  unenforceable,  illegal,  or
inoperable, its invalidity shall not affect the validity and effect of the other
provisions  hereof  except to the extent  that the  parties  may claim a lack or
insufficiency  of  consideration  if  provisions  involving   consideration  are
stricken or modified.

                       VI. Construction and Interpretation

     This  Agreement  shall be governed by and construed in accordance  with the
laws of the State of Arizona.

     This  Agreement is not intended to  constitute a severance  agreement or to
provide severance benefits and it shall be construed and interpreted in a manner
consistent therewith.

                            VII. Delays or Omissions

     No delay or omission to exercise any right,  power,  or remedy  accruing to
the  Company  as a result of any  breach  or  default  by  Employee  under  this
Agreement  shall  impair  any such  right,  power,  or  remedy,  nor shall it be
construed as a waiver of or acquiescence in any such breach or default, or of or
in any similar breach or default  occurring  later:  nor shall any waiver of any
single  breach or  default  be deemed a waiver  of any other  breach or  default
occurring before or after that waiver.

                              VIII. Attorney's Fees

     In the  event of  litigation  arising  out of the  subject  matter  of this
Agreement,  the  prevailing  party  shall be entitled  to recover  such  parties
reasonable  attorney's fees and related costs and expenses  incurred as a result
of litigation.

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                           IX. Successors and Assigns

     This Agreement and  Employee's  rights and duties created by this Agreement
shall not be  assignable  or delegable by Employee.  The Company  shall have the
right to transfer,  assign or delegate all or any part of this Agreement and the
rights and duties  hereunder to any business that is controlled by or affiliated
with the  Company  or to any  successor  acquiring  the  Company,  its assets or
business, in whole or part.

     IN WITNESS  WHEREOF the parties have  executed  this  Agreement on the date
first written above.

ARIZONA PUBLIC SERVICE COMPANY

By: William J. Post
    ----------------------------
    William J. Post
    Chief Executive Officer

William L. Stewart     12/13/99
-----------------------------------
William L. Stewart
