POWER COORDINATION AGREEMENT

                                       of

                               SEPTEMBER 15, 1955


                                     between


                               SALT RIVER PROJECT

                            AGRICULTURAL IMPROVEMENT

                               AND POWER DISTRICT



                                       and



                             ARIZONA PUBLIC SERVICE

                                     COMPANY













                          POWER COORDINATION AGREEMENT

                                TABLE OF CONTENTS

                                                                            Page

                  Explanatory Recitals                                        1

ARTICLE I     -   Cooperation in Development and Operation                    2

ARTICLE II    -   Additions to System Facilities                              3

ARTICLE III   -   Sale of Power                                               4

ARTICLE IV    -   Reciprocal Services                                         5

ARTICLE V     -   Committees                                                  5

ARTICLE VI    -   Conditions Of Interconnected Operation                      7

ARTICLE VII   -   Metering                                                   12

ARTICLE VIII  -   Settlements                                                13

ARTICLE IX    -   Arbitration                                                13

ARTICLE X     -   Miscellaneous Provisions                                   15

ARTICLE XI    -   Term                                                       17

                          POWER COORDINATION AGREEMENT
                          ----------------------------

0.1      THIS POWER COORDINATION  AGREEMENT,  entered into as of the 15th day of
         September,  1955, between SALT RIVER PROJECT  AGRICULTURAL  IMPROVEMENT
         AND POWER DISTRICT,  an Agricultural  Improvement  District,  organized
         under the laws of the State of Arizona  (here  after  in this Agreement
         and in the Schedules  attached  hereto called  "District")  and ARIZONA
         PUBLIC  SERVICE  COMPANY,  an Arizona  corporation  (hereafter  in this
         Agreement and in the Schedules attached hereto called "Company"),

                                   WITNESSETH:

0.2      WHEREAS,  District  owns and  operates  an  electric  system  supplying
         electric  service in the central  portion of the State of Arizona,  and
         Company owns and operates an electric system supplying electric service
         in the  central  portion of the State of Arizona and  elsewhere  in the
         State; and

0.3      WHEREAS,  the  electric  systems of District  and of Company in central
         Arizona have long been  interconnected at various points at which power
         has been sold and interchanged  between the systems,  and a substantial
         degree of coordination has been established and maintained  between the
         two systems for purposes of improving  the  quality,  reliability,  and
         economy of electric service in the respective territories served; and

0.4      WHEREAS,  an agreement  hereinafter  referred to as the  "Agreement  of
         August  31,  1955"  was  entered  into  between  District  and  Company
         providing,  among  other  things,  (i) for  clear  delimitation  of the
         respective  service  territories  and types of load of District  and of
         Company,  thereby facilitating  orderly and economical  development and
         expansion of the facilities of each system,  (ii) for  superseding  and
         cancelling  various existing  agreements  between District and Company,
         the terms of such  agreements  being no longer adequate and appropriate
         hr operating and economic  conditions now obtaining and foreseen in the
         development of the territories served, and (iii) for entering into a
                                        1

         new  agreement to provide for sales and  interchange  of power  between
         District  and  Company  in  larger  amounts  and on the  basis  of more
         extensive  coordination  in operation and  development  of the electric
         systems of District and Company; and

0.5      WHEREAS,  the parties  believe that further  coordination on an assured
         and continuing basis will yield important  benefits to consumers and to
         the  economic  growth  of the  territories  served  and to  each of the
         systems, and that among such benefits will be the following:

         (a)      The  combined  power loads of the two systems can be supplied,
                  with adequate  reserve  capacity by less  aggregate  installed
                  generating  capacity with consequent net savings in investment
                  and expenses,

         (b)      Emergency  conditions  in either  system  can be met with less
                  likelihood of curtailment or impairment of electric service,

         (c)      New   installations   of   generating   facilities  to  supply
                  increasing power requirements can be made on a more economical
                  basis as to timing, unit sizes, location, and ownership,

         (d)      Fuller   utilization   can  be  made  of  more  efficient  and
                  economical  generating facilities and of interconnections with
                  other power systems, and

         (e)      When and as additional  hydro power may become  available from
                  new  developments on the Colorado River,  such hydro power can
                  be more widely and  economically  distributed to consumers and
                  better  utilization  can be realized for  available  secondary
                  hydro energy;

0.6      NOW,  THEREFORE,  in  consideration  of the  premises and of the mutual
         benefits from the covenants hereinafter set forth, IT IS AGREED:

             ARTICLE I -- COOPERATION IN DEVELOPMENT AND OPERATION
             -----------------------------------------------------

1.1      The provisions of this agreement,  as hereinafter set forth,  relate to
         cooperation in the development and operation of the respective electric
                                       2

         systems of District and of Company and to sale and interchange of power
         and to mutual  assistance  between  the two  systems.  Each  party will
         comply with said provisions and assume and fulfill the responsibilities
         assigned to it therein.

1.2      The parties, through authorized representatives, will regularly consult
         with  each  other  and  cooperate  as to  planning  for  immediate  and
         subsequent  steps  in the  development  of  their  respective  electric
         systems and as to maintaining coordination in operation of said systems
         and realizing the benefits attainable therefrom.

                  ARTICLE II -- ADDITIONS TO SYSTEM FACILITIES
                  --------------------------------------------

2.1      As an initial stage in coordination of system development,  the parties
         will do those things set forth in Sections 2.2, 2.3, ant 2.4 following.

2.2      New  District   Generating   Station  --  District  will  proceed  with
         construction of a new steam-electric  generating  station,  hereinafter
         called "Agua Fria Generating Station," to be located between the cities
         of  Glendale  and  Peoria,  northwest  of the  city of  Phoenix,  which
         generating  station shall contain two  generating  units with a nominal
         capacity of 100,000  kilowatts  each with  provision  in its design and
         construction  for  installation of additional  generating  units.  Said
         generating  station  shall include  transformers  connecting it to a 69
         kilovolt bus which shall be adequately connected District's  electrical
         system. District will make available to Company suitable space adjacent
         to  said  69  kilovolt  bus for the  installation  by  Company  of a 69
         kilovolt  bus and  terminal  facilities  for at least five 69  kilovolt
         circuits  and  will  grant  to  Company,   without   charge   therefor,
         appropriate  easements  on its Agua Fria site for said bus and terminal
         facilities and for Company's 69 kilovolt circuits  connecting  thereto.
         District  will arrange the  construction  schedules  for said Agua Fria
         Generating  Station  on  the  basis  of  nominal  dates  for  beginning
         commercial  operation of the first generating unit on April 1, 1957, of
         the second  generating  unit on April 1, 1958, and District will in any
         event complete construction ready for commercial operation of the first
         generating  unit by June 1, 1957, and of the second  generating unit by
         June 1, 1958, 3

         unless completion at such times be prevented by uncontrollable forces.

2.3      Company  Transmission  Connections  -- Company will provide 69 kilovolt
         transmission feeders and associated  facilities to connect its electric
         system to the 69  kilovolt  bus of said Agua Fria  Generating  Station,
         which  feeders  shall  be of  adequate  capacity  to  carry  from  said
         generating  station into Company's electric system all of the power, as
         set forth in Service Schedule A and Service Schedule C hereof, which is
         to be  delivered  by  District  to  Company  from  time  to time at the
         delivery  point  located  at  said  generating  station.  Company  will
         provide,  ready for service  when said  generating  units are ready for
         service, such of said 69 kilovolt feeders as are needed at those times,
         unless provisions at such times be prevented by uncontrollable forces.

2.4      Deferral  of  Company  Generating  Station  --  Company  will defer its
         arrangements  heretofore made for constructing a similar new generating
         station  at a  location  east of the  City of  Phoenix  which  had been
         scheduled for initial operation in the early part of 1957.

                          ARTICLE III -- SALE OF POWER
                          ----------------------------

3.1      District will sell  initially a substantial  amount of power to Company
         hereunder,  and it is  contemplated  by the parties that they will from
         time to time  arrange for other sales of power from one to the other in
         such  amounts and for such periods as will be  consistent  with orderly
         development of their respective systems and assurance of adequate power
         supply to the territories  served. It is contemplated that arrangements
         for such  inter-system  power  sales  will be  incorporated  in service
         schedules which, upon their execution by authorized  representatives of
         the parties,  shall be parts of this  agreement  for the periods  which
         they respectively cover.

3.2      The  following  service  schedules  providing  for sale and purchase of
         power are hereby made a part of this agreement:

         Service Schedule A -- Long-term Sale of Power by District to Company.

         Service Schedule B -- Sale of 12,000 Kilowatts by District to Com-
                                       4

         pany (continuing until June 1, 1961).

         Service  Schedule C -- Sale of 40,000  Kilowatts by District to Company
         (continuing from early 1958 to early 1960).

                        ARTICLE IV - RECIPROCAL SERVICES
                        --------------------------------

4.1      It is  contemplated by the parties that they will from time to time put
         into effect  specific  arrangements  for reciprocal  services and other
         measures for coordination of the operation of their respective electric
         systems for the purpose of achieving economies in cost and improvements
         in quality and reliability of power supply to the  territories  served.
         It is  contemplated  that such  arrangements  will be  incorporated  in
         service schedules which,  upon their execution,  shall be parts of this
         agreement for the respective periods which they cover.

4.2      The following service schedules  providing for reciprocal  services are
         hereby made a part of this agreement:

         Service   Schedule  D  --  Energy   Interchange  and  Spinning  Reserve
         Interchange.

         Service Schedule E -- Capacity  Equalization  ant Reciprocal  Emergency
         Assistance.

         Service Schedule F -- Transfer of Power to Fringe-Area Customer Service

         Service Schedule G -- Parker Power Interchange.

         Service  Schedule H --  Coordination  of  Interconnecting  Transmission
         Circuits.

                             ARTICLE V -- COMMITTEES
                             -----------------------

5.1      As a means of securing effective  cooperation in the planning of system
         development  and of dealing on a prompt and orderly  basis with various
         technical and operating  problems which arise in connection with system
         coordination  under changing  conditions,  the parties will establish a
         "Coordination  Committee"  and an "Operating  Committee",  each charged
         with certain responsibilities hereunder.

5.2      Coordination  Committee-- The  Coordination  Committee shall consist of
         two  representatives,  one  designated  by each  party,  and each  such
         representative  shall  be  authorized  by  the  party  by  whom  he  is
                                        5

         designated  to act on its behalf with respect to those  matters  herein
         provided to be  responsibilities  of the  Coordination  Committee.  The
         functions and  responsibilities of the Coordination  Committee shall be
         (i) to establish general policies to be followed in coordination of the
         operation of the electric  systems of the parties,  consistent with the
         provisions  of  this  agreement,   (ii)  to  review   periodically  the
         prospective aggregate power requirements of the two systems, to arrange
         for investigations with respect to time, nature, location and ownership
         of additional generating capacity and related transmission  facilities,
         and with respect to possible  power  purchases  from external  sources,
         which will provide for such aggregate  power  requirements  in a manner
         consistent  with  overall  effectiveness  and  economy,  and to present
         recommendations  as to  such  matters  to the  parties,  (iii)  to make
         recommendations concerning changes in principal network delivery points
         and to make  arrangement for any such changes  approved by the parties,
         (iv) to exercise  general  supervision  and guidance over the Operating
         Committee,  (v) to  consider  and  act  upon  matters  referred  to the
         Coordination Committee by the Operating Committee,  and (vi) to do such
         other  things as are  provided  herein and as may be provided  for from
         time to time  by the  parties  to this  agreement;  provided  that  the
         Coordination  Committee  shall have no  authority  to modify any of the
         provisions of this agreement (including any service schedules effective
         hereunder)  except as to items where  modification  is  specified to be
         within the scope of the Coordination  Committee's  responsibility.  Any
         decision or agreement by the Coordination  Committee shall be effective
         when signed by both  members of the  Committee.  Each party will notify
         the other party promptly of the  designation of its  representative  on
         the  Coordination  Committee  and  of any  subsequent  change  in  such
         designation.  Either party may  designate an alternate or substitute to
         act as its  representative  on the Coordination  Committee on specified
         occasions or with respect to specified matters.

5.3      Operating  Committee -- The Operating  Committee  shall consist of four
         representatives,   two   designated  by  each  party,   and  each  such
         representative  shall  be  authorized  by  the  party  by  whom  he  is
         designated  to act on its behalf with respect to those  matters  herein
         provided  to  be  responsibilities  of  the  Operating  Committee.  The
         functions and  responsibilities of the Operating Committee shall be (i)
         to establish  procedures and standard  practices,  consistent  with the
         provisions  hereof,  for the  guidance  of load  dispatchers  and other
         operating  employees in the respective  systems as to matters affecting
         interconnected op-
                                       6

         rations of the respective  systems,  delivery of power,  interchange of
         energy and spinning reserve, reciprocal emergency assistance, and other
         similar operating  matters,  (ii) to establish  procedures and standard
         practices  as to  determinations  of costs and  expenses  and of energy
         losses in connection  with energy  interchanges  and other  intersystem
         transactions   hereunder,   (iii)  to   establish   detailed   metering
         arrangements required in connection with transactions  hereunder,  (iv)
         to bring to the attention of the Coordination Committee matters needing
         its  attention,  and (v) to do such other  things as are  provided  for
         herein;  provided that the Operating  Committee shall have no authority
         to  modify  any of the  provisions  of this  agreement  (including  any
         service  schedules  effective  hereunder)  except  as  to  items  where
         modification  is  specified  to be within  the  scope of the  Operating
         Committee's  responsibility.  The  establishment  of any  procedure  or
         practice  and  any  other  action  or  determination  by the  Operating
         Committee,    within   the   scope   of   the   Operating   Committee's
         responsibility,  shall  be  effective  when  signed  by  at  least  one
         designated  representative  of each of the  parties.  Each  party  will
         notify  the  other   party   promptly  of  the   designations   of  its
         representatives  on the  Operating  Committee  and  of  any  subsequent
         changes in such designations.

5.4      Disagreements  -- If the Operating  Committee  shall disagree as to any
         action to be taken or decision to be made, or as to the need for taking
         any  action or making  any  decision,  or as to  whether  any matter is
         within  the  scope  of  the  Operating   Committee's   responsibilities
         hereunder,  the question or questions at issue shall be referred to the
         Coordination   Committee  for  its  action  or  instructions.   If  the
         Coordination Committee be unable to reach agreement with respect to any
         matter  referred to it by the Operating  Committee,  or with respect to
         any other matter  within the scope of its  responsibilities  hereunder,
         the  Coordination  Committee  may at its  discretion  request  that the
         matter be referred to arbitration in the manner  provided in Article IX
         hereof.  Reference to arbitration shall be mandatory only in respect of
         those matters which are specifically made subject to arbitration by the
         provisions of this agreement.

               ARTICLE VI - CONDITIONS OP INTERCONNECTED OPERATION
               ---------------------------------------------------

6.1      Interconnection  Points - For purposes hereof the following terms shall
         have the meanings indicated:
                                       7

         (a)      A   "major   interconnection   point"   means   a   point   of
                  interconnection between the electrical networks of the parties
                  into which the  transmission or transformer  facilities of the
                  respective  systems  are able to deliver  or to receive  large
                  amounts of power and the  location of which in relation to the
                  respective   systems  is  such  that   power   being  sold  or
                  interchanged can be effectively and  satisfactorily  delivered
                  and utilized.  The following major interconnection  points are
                  established hereunder:

                  (i)      At a location  west of the City of Phoenix  adjoining
                           Company's Phoenix  Generating Station and the Phoenix
                           Terminal  Substation  of the  Bureau of  Reclamation,
                           where  the  systems  can  be   interconnected  at  69
                           kilovolts or at 12 kilovolts or at both voltages,

                  (ii)     At  or  adjoining  District's  Agua  Fria  Generating
                           Station at 69 kilovolts,  when the first unit of said
                           generating  station  shall be completed and ready for
                           operation,

                  (iii)    At or  adjoining  Mesa  Substation  of The  Bureau of
                           Reclamation at 69 kilovolts.

                  Establishment of additional major interconnection  points from
                  time to time and the  ownership and physical  arrangements  at
                  such points shall be as recommended by the Operating Committee
                  and approved by the  Coordination  Committee.  Existing  major
                  interconnection  points,  except a principal  network delivery
                  point  under a  service  schedule,  may  from  time to time be
                  discontinued upon  recommendation  of the Operating  Committee
                  and approval of the Coordination  Committee.  Responsibilities
                  of the  parties for  operation  and  maintenance  at the major
                  interconnection   points  shall  be  as   established  by  the
                  Operating  Committee  and  shall  be  evidenced  by  operating
                  memoranda covering such matters.

         (b)      A   "minor   interconnection   point"   means   a   point   of
                  interconnection  between  the  electrical  facilities  of  the
                  parties, either at substations or at points on transmission or
                  distribution  feeders,  where power can be both  delivered and
                  received  between the systems in  relatively  small amounts as
                  compared to major interconnection  points. The location of and
                  arrangements for minor interconnection points, for regular use
                  and for emergency use,
                                       8

                  shall be such as may from time to time be  recommended  by the
                  Operating   Committee   and   approved  by  the   Coordination
                  Committee.

         (c)      An   "indirect   interconnection   point"  means  a  point  of
                  interconnection  between  the  electrical  system of one party
                  hereto and the electrical system of a third party, which third
                  party's  electrical  system is also  interconnected at another
                  point to the electrical system of the other party hereto.

6.2      Parallel  Operation  -- The  electrical  systems of the  parties  shall
         normally  be  operated  in  parallel  (i) at all major  interconnection
         points,  (ii) at such  minor  interconnection  points as the  Operating
         Committee  shall from time to time  designate for normal closed circuit
         operation,  and (iii) at indirect  interconnection  points  where third
         party  arrangements  require such  parallel  operation,  or where third
         party  arrangements  permit such  parallel  operation and the Operating
         Committee shall  determine that such parallel  operation is a desirable
         practice from the aspect of coordination between the electrical systems
         of the parties hereto.  Temporary  emergency  interconnections at other
         points may be arranged from time to time by the Operating Committee, as
         circumstances  may require.  It is the intent of the parties that their
         network systems shall normally be operated as fully  interconnected  as
         may be necessary or convenient to protect  quality and  reliability  of
         service to consumers without involving undue  complications and expense
         for intersystem metering and energy accounting.  Deviations from normal
         parallel operation may be made as directed by the Operating  Committee,
         or as  provided  for in  standard  practice  adopted  by the  Operating
         Committee,  or as may under  special  temporary  conditions be arranged
         between the respective load dispatchers.

6.3      Outage  Schedules -- The parties will cooperate in scheduling the times
         and  durations of removal from  service of major  generating  units and
         important transmission circuits for inspection,  maintenance or repair,
         to the end that hazard to or  interference  with  service to  consumers
         will be minimized.  The arranging of such outage coordination schedules
         shall be a responsibility of the Operating Committee.

6.4      Electrical  Disturbances  -- Each party will insofar as  practicable to
         construct,  operate and maintain its system and  facilities as to avoid
         or minimize the likelihood of a disturbance originating from its system
         which might cause impairment of service in the system of the other
                                       9

         party or in any third-party  system  interconnected  with the system of
         the other party.

6.5      Frequency -- Power  supplied by either party to the other in accordance
         with service schedules  hereunder shall be at a nominal frequency of 60
         cycles  per  second,  except as in any  service  schedule  specifically
         provided  otherwise.  Insofar as  interconnected  system  frequency  is
         within the control of the parties,  it shall be a responsibility of the
         Operating Committee to establish operating arrangements for maintaining
         frequency  within  limits  satisfactory  for the  types of power  loads
         served by the two systems.

6.6      Tie Line Load Control -- The respective responsibilities of the parties
         with respect to tie line load control at interconnection points and the
         types of  control  equipment  installed  for such  purpose  shall be in
         accordance with standard practices established from time to time by the
         Operating Committee.

6.7      Relays -- The types  and  settings  of relay  equipment  installed  for
         control of circuits  connected  to  interconnection  points shall be in
         accordance with standard practices established from time to time by the
         Operating Committee.

6.8      Voltage -- Variations and  fluctuations  in voltage at  interconnection
         points, and at other delivery points for power supplied by one party to
         the other,  shall be kept within  limits  which will  minimize  adverse
         effects upon operation of the electrical system of either party or upon
         service supplied by either system. The respective  responsibilities  of
         the parties with respect to voltage  control at such points shall be in
         accordance with standard practices established from time to time by the
         Operating Committee.

6.9      Reactive  Kilovolt-Amperes -- Except as may be specifically provided in
         a service schedule hereunder or as may be arranged in specific cases by
         the  Operating  Committee,  neither  party shall be entitled to receive
         kilovars  from the other party or obligated  to supply  kilovars to the
         other party. Each party will cooperate with the other party to minimize
         unintended flow of kilovars between the systems. It shall be within the
         responsibility of the Operating  Committee to adopt standard practices,
         including appropriate charges, if any, for
                                       10

         scheduling flow of kilovars  between the systems under  conditions when
         there may be a mutual  advantage from such flow and for  controlling or
         limiting  unscheduled kilovar flow. In the event of any disagreement in
         connection  with the supply of  kilovars  either  party  shall have the
         right to have the matter submitted to arbitration.

6.10     Scheduling of Power Deliveries -- The Operating Committee shall arrange
         for all power  transactions  hereunder to be accounted for on the basis
         of  amounts   scheduled   between  the  respective  load   dispatchers.
         Arrangements  made  therefor by the Operating  Committee  shall provide
         that the  respective  load  dispatchers  will  maintain in  duplicate a
         running record of cumulative  deviations from aggregate schedules,  and
         that such  cumulative  deviations  will be compensated  for by opposite
         deviations  made  as  promptly  as  practicable,   provided  that  such
         compensatory deviations are to be made under generally similar load and
         resource  conditions  or to be  subject to  adjustment  factors to take
         account of  differences  in load and resource  conditions  between time
         when initial deviations occur and time when compensatory deviations are
         made.

6.11     Temporary  Interchange  Arrangements  -- In cases  where,  from time to
         time, there may be a mutual advantage from sale or interchange of power
         between  the  parties  upon a basis  not  provided  for in any  service
         schedule   then  in  effect  and  the   circumstances   are  such  that
         arrangements  must be made promptly in order to realize such advantage,
         or  in  cases  of  emergency  or of  temporary  and  unusual  operating
         conditions,   temporary  arrangements for  individual  transactions  or
         classes  of  transactions  may  be  made  by the  Operating  Committee;
         provided,  however,  that  no  continuing  commitment  involved  in any
         arrangement so made at any time by the Operating  Committee,  under its
         responsibilities  hereunder,  shall extend for a longer  period than 30
         days.

6.12     Operating  Data -- Each party will make  available  to the other  party
         operating data with respect to effective capacities of generating units
         and transmission circuits,  incremental costs of power sources, current
         and  estimated  future power loads of its electric  system and sections
         thereof,  and similar matters,  to the extent that such data are needed
         by the  Coordination  Committee  and  the  Operating  Committee  in the
         discharge of their responsibilities hereunder and are needed in
                                       11

         connection with load dispatching and energy accounting for transactions
         hereunder.  It shall be a responsibility of the Operating  Committee to
         arrange  for  reasonable  opportunity  for  each  party to  review  the
         supporting data for the information so supplied by the other party.

                             ARTICLE VII -- METERING
                             -----------------------

7.1      Metering Facilities -- Arrangements with respect to location,  type and
         ownership of metering facilities required for purposes of control of or
         settlements  for power  transactions  hereunder  shall be in accordance
         with the  provisions  of the  service  schedules  covering  such  power
         transactions.  The owner of a metering installation,  the registrations
         of which are important in connection with  settlements for transactions
         hereunder,  upon  request  of the  other  party,  will  make  available
         suitable space and facilities for installation of check metering.

7.2      Testing and Reading of Meters -- Metering equipment,  the registrations
         of which are involved in settlements for transactions hereunder,  shall
         be  inspected  and tested by the owner at annual  intervals  or at such
         shorter  intervals as may be directed by the Operating  Committee,  and
         any inaccuracy  disclosed by such tests shall be promptly  corrected by
         the owner. Additional inspections and tests at particular installations
         shall  be  made  by  the  owner  upon   request  of  the  other  party.
         Representatives of the other party shall be afforded  opportunity to be
         present at all such inspections and tests. If at any test a meter shall
         be found to be  inaccurate by more than 1%, fast or slow, an adjustment
         shall  be  made  in  settlements   hereunder  between  the  parties  to
         compensate for the effect of such  inaccuracy  over a preceding  period
         extending to the second  preceding  meter  reading or over such shorter
         period as the inaccuracy  may be determined to have existed.  If at any
         time a meter should fail to register or its  registration  should be so
         erratic as to be meaningless,  the estimated  correct  registration for
         billing  purposes  shall be based  upon  records  of check  meters,  if
         available,  or otherwise upon the best  obtainable  data.  Kilowatthour
         meters  involved in settlements  hereunder shall be read monthly by the
         owner,  and  representative  of  the  other  party  shall  be  afforded
         opportunity to be present at such readings.  Arrangements  with respect
         to reading of meters belonging to third parties, the registrations
                                       12

         of which are involved in settlements for transactions hereunder,  shall
         be a responsibility of the Operating Committee.

                           ARTICLE VIII -- SETTLEMENTS
                           ---------------------------

8.1      Accounting Period -- Accounting period for transactions hereunder shall
         be one month.  Such  one-month  period shall be a calendar month unless
         the  Coordination  Committee shall specify a one-month  period ending a
         designated number of days before the end of each calendar month.

8.2      Billing and Payment -- Bills for amounts  payable for any month by each
         party to the other  hereunder  shall be  rendered on or before the 14th
         day of the  succeeding  month  and shall be due on the 19th day of such
         succeeding month or on the 5th day after receipt of bill,  whichever be
         later,  provided,  however, that in the event that any amount which has
         become due District for power and energy transactions  hereunder is not
         received by District prior to the due date of District's fuel bills for
         such month and any such bill for fuel owed to  Company  shall have been
         paid on or before the due date,  then the energy charge  portion of the
         amount so due  District  for such month shall be  increased  by 0.635%.
         Payment  shall be made at such office of the party to which  payment is
         due as that party shall designate by written  notice.  Amounts not paid
         on or before the due date shall be payable with interest accrued at the
         rate of 1/2 percent  compounded  monthly  computed from the due date to
         the date of payment.

8.3      Disputed  Bills -- In case any portion of any bill be in  dispute,  the
         undisputed  amount shall be paid when due, and the  remainder,  if any,
         upon determination of the correct amount,  shall be paid promptly after
         such  determination  with  interest  accrued at the rate of 1/2 percent
         compounded monthly computed from the original due date.

                            ARTICLE IX -- ARBITRATION
                            -------------------------

9.l      In the event the parties be unable to reach agreement with respect to a
         matter herein  specified to be subject to arbitration,  or in the event
         the  Coordination  Committee  shall  request  that an  issue  shall  be
         submitted  to   arbitration,   the  procedure   with  respect  to  such
         arbitration
                                       13

         shall be as set forth in Sections 9.2 through 9.6 hereof.

9.2      Either  party  by  written  notice  to the  other  party  may  call for
         appointment of a three-person board of arbitration, designating in such
         notice  one  person  appointed  by it to  serve  as a  member  of  such
         three-person   arbitration  board.  The  other  party  thereupon  shall
         similarly  appoint a second  person and the two  persons  so  appointed
         shall  endeavor to agree upon and secure the services of a third person
         to complete such three-person arbitration board.

9.3      If,  within  twenty days after the  appointment  of the first member of
         said arbitration  board by one party, the other party shall have failed
         to  appoint  a second  member,  or if  within  fifteen  days  after the
         appointment of a second member,  no third member shall have been agreed
         upon and secured, either party, with written notice to the other party,
         may call upon the person who is the senior  Judge of the United  States
         District  Court in and for the  District of Arizona to appoint a second
         and a third  member,  or a third  member,  as the case  may be.  If the
         person so called upon shall fail for ten (10) days to act,  then either
         party with written notice to the other party may call successively upon
         (i) any other person who is a Judge of the United States District Court
         in and for the  District  of  Arizona,  or (ii)  persons  who are  then
         members of the Supreme Court of Arizona in the order of their seniority
         in office, to make such appointment.

9.4      The board of  arbitration  appointed as provided in Section 9.2 or 9.3,
         shall hear the  evidence  submitted  by the  parties,  and may call for
         additional  information.  The  decision,  submitted  in  writing,  by a
         majority  of the  arbitration  board,  shall  be  conclusive  as to the
         disagreement  submitted for  arbitration  and shall be binding upon the
         parties.

9.5      Each party  shall bear the fee and  personal  expenses of the member of
         the  arbitration  board appointed by or for it, and all other costs and
         expenses  of the  arbitration  shall be  borne  in  equal  parts by the
         parties,  unless the  decision of a majority of the  arbitration  board
         shall specify a different apportionment of such costs and expenses.

9.6      Except as otherwise provided in this Article and in cases where the
                                       14

         parties  may  otherwise  agree,  the  procedure  for  hearings  in  any
         arbitration  proceeding  conducted hereunder shall follow to the extent
         practical the  procedure set forth in Rules V and Vl of the  Commercial
         Arbitration Rules of the American Arbitration  Association,  as amended
         and in effect January 1, 1952.

9.7      The foregoing provisions set out in Sections 9.2 through 9.6 hereof are
         agreed to by the parties as the arbitration  procedures to be followed,
         rather than the  procedures  set out in Article 3, Chapter 27,  Arizona
         Code  Annotated,  1939. In the event the  following of such  procedures
         should for any reason be or become invalid under Arizona law, or if the
         decision of the arbitration  board  thereunder  should be unenforceable
         under the Arizona law, then the parties agree, as an alternative to the
         said  procedures  set out in Sections  9.2  through  9.6, to follow the
         procedures  for  arbitration  then  provided for by or permitted  under
         Arizona  law,  and to take such steps as are  necessary  to follow such
         procedures.

                      ARTICLE X -- MISCELLANEOUS PROVISIONS
                      -------------------------------------

10.1     Uncontrollable  Forces -- Neither  party shall be  considered  to be in
         default in performance of any obligation hereunder or under the service
         schedules  attached  hereto if failure of  performance  shall be due to
         uncontrollable  forces,  the term  "uncontrollable  forces" meaning any
         cause  beyond the  control of the party  affected,  including,  but not
         limited to,  failure of facilities,  flood,  earthquake,  storm,  fire,
         lightning,  epidemic, war, riot, civil disturbance,  labor disturbance,
         sabotage, and restraint by court or public authority, which by exercise
         of due foresight such party could not reasonably  have been expected to
         avoid,  and which by  exercise of due  diligence  it shall be unable to
         overcome.  Neither party shall,  however,  be relieved of liability for
         failure of  performance if such failure be due to causes arising out of
         its own negligence or to removable or remediable  causes which it fails
         to remove or remedy with reasonable dispatch. Nothing contained herein,
         however,  shall be  construed  to  require  either  party to prevent or
         settle a strike against its will.

10.2     Restriction  on  Use  of  Irrigation  Water  --  Without  limiting  the
         obligation  of  District  to supply  and/or  deliver  power to Company,
         nothing in this agreement nor in any service schedules now or hereafter
         attached shall require the District in furnishing power to Company to
                                       15

         waste water required for  irrigation  within the boundaries of the Salt
         River Reservoir District, as such boundaries are particularly described
         in Section 3 of Article IV of the Articles of Incorporation of the Salt
         River Valley Water Users' Association, filed February 9, 1903.

10.3     Waiver -- Any waiver by a parry of its rights with respect to a default
         under this  agreement,  or with respect to any other matter  arising in
         connection with this agreement, shall not be deemed to be a waiver with
         respect to any  subsequent  default or matter.  No delay,  short of the
         statutory  period of  limitations,  in asserting or enforcing any right
         hereunder shall be deemed a waiver to such right.

10.4     Amendments -- Neither this  agreement nor any of the service  schedules
         attached, or to be attached,  shall be deemed to be amended unless such
         amendments  shall be formally  executed on behalf of each party and the
         execution  thereof  be  authorized,   ratified,   or  approved  by  the
         respective Boards of Directors of the parties.

10.5     Notices -- (a) Any  notice,  demand,  or request  provided  for in this
         agreement or given or made in connection with this agreement to or upon
         District  shall be deemed to be properly  given or made if delivered or
         sent  by  registered   mail  to  the  Secretary,   Salt  River  Project
         Agricultural  Improvement and Power District,  P. O. Box 1980, Phoenix,
         Arizona.

                  (b)  Any  notice,  demand,  or  request  provided  for in this
         agreement  to or upon Company  shall be deemed to be properly  given or
         made if delivered or sent by registered mail to the Secretary,  Arizona
         Public Service Company, P. O. Box 2591, Phoenix, Arizona.

                  (c) The designation or the address of any person  specified in
         this paragraph 10.5 may be changed at any time by written notice.

                  (d) Notices and requests of a routine  character in connection
         with  delivery or receipt of power or in connection  with  operation of
         facilities  shall be given in such  manner as the  Operating  Committee
         from time to time shall arrange.

10.6     Regulatory  Authorities -- This agreement is subject to valid laws, and
         to valid orders, rules, and regulations of duly constituted  regulatory
         authorities having jurisdiction.
                                       16

10.7     Successors  and Assigns -- Neither party,  without the written  consent
         and approval of the other party hereto,  shall assign this agreement or
         any of the service schedules now or hereafter attached hereto except as
         a part of any transaction or  transactions  effected in compliance with
         Article X of the Agreement of August 31, 1955,  relating to "TRANSFERS,
         MERGERS  AND  ASSIGNMENTS."  Subject to the  foregoing  provisions  and
         restrictions  herein set forth and referred to, this  agreement and the
         attached  service  schedules  shall be binding  upon,  and inure to the
         benefits  of the parties  hereto and their  respective  successors  and
         assigns.

10.8     Captions and  Headings -- The  captions and headings  appearing in this
         agreement and in service  schedules  hereunder  are inserted  merely to
         facilitate  reference and shall have no bearing upon the interpretation
         of the provisions.

10.9     Article,  Section and  Paragraph  References -- References by number to
         articles,  sections and  paragraphs  in this  agreement  and in service
         schedules  attached or to be attached  are to  articles,  sections  and
         paragraphs of the particular  document in which the references  appear,
         except as such references are specifically to other documents,  and any
         reference  to  service  schedules  shall  refer  to  service  schedules
         attached to this Power Coordination Agreement.

10.10    Conditions  and  Provisions  of  Agreement  of August 31,  1955 -- This
         agreement and attached  service  schedules  fulfill all  conditions and
         provisions of Article III of the "Agreement of August 31, 1955."

                               ARTICLE XI -- TERM
                               ------------------

11.1     Effective Date -- This agreement shall become  effective as of the time
         when  the  conditions  and  approvals  required  by  Article  XV of the
         Agreement of August 31, 1955, shall have been fulfilled and obtained.

11.2     Duration -- This agreement shall continue in effect indefinitely unless
         and until  terminated  as  provided  in  paragraphs  (a) or (b) of this
         section.

         (a)      District may terminate this agreement by giving written notice
                  to  Company  three  (3)  years  in  advance  of  the  date  of
                  termination  designated in such notice,  and such  termination
                  shall concurrently terminate all service schedules.
                                       17

         (b)      In the  event,  at any time,  (i) that all  service  schedules
                  theretofore  in  effect   hereunder  have  been  cancelled  or
                  terminated in accordance with the provisions  thereof or valid
                  written notices have been given  cancelling or terminating all
                  such  service  schedules  in  accordance  with the  provisions
                  thereof,  and (ii)  that no new  service  schedules  have been
                  approved by the parties to become  effective at a future date,
                  and (iii) that no new service  schedules  shall be the subject
                  of bona fide  negotiation  between the  parties,  then in such
                  event this  agreement  may be  terminated as of any date later
                  than the expiration of all service schedules by written notice
                  given by either  party to the other  party one year in advance
                  of the date of termination designated in such notice.

                  IN WITNESS WHEREOF,  the respective parties hereto have caused
         this instrument to be executed on their behalf by their duly authorized
         officers and their  corporate seals to be hereunto  affixed,  all as of
         the date and year first above written.

                                    SALT RIVER PROJECT AGRICULTURAL
                                    IMPROVEMENT AND POWER DISTRICT


                                    By   VICTOR I. CORBELL
                                      -----------------------
                                             President


ATTEST:


         A. L. MONETTE
- -------------------------------
           Secretary
                                       18

APPROVED:

Jennings, Strouss, Salmon & Trask



By:      J. A. RIGGINS, JR.
   -----------------------------
Legal Counsel
Salt River Project Agricultural
Improvement and Power District



                                            ARIZONA PUBLIC SERVICE COMPANY



                                            By:      WALTER T. LUCKING
                                               ----------------------------
                                                         President


ATTEST:


          [Illegible]
- ---------------------------------
           Secretary



APPROVED:

Snell & Wilmer



By       NICHOLAS H. POWELL
  -------------------------------
Legal Counsel
Arizona Public Service Company
                                       19

                                    APPROVAL
                                    --------

         The  foregoing  "Power  Coordination  Agreement of September  15,1955",
between  Salt River  Project  Agricultural  Improvement  and Power  District and
Arizona Public Service Company,  and the following designated service schedules,
to-wit:

                  Service Schedule A -- Long-Term  Sale of Power by  District to
                                        Company, and Supplement No. 1 to Service
                                        Schedule A.

                  Service Schedule B -- Sale of 12,000  Kilowatts by District to
                                        Company.

                  Service Schedule C -- Sale of 40,000  Kilowatts by District to
                                        Company.

                  Service Schedule D -- Energy  Interchange and Spinning Reserve
                                        Interchange.

                  Service Schedule E -- Capacity   Equalization  and  Reciprocal
                                        Emergency Assistance.

                  Service Schedule F -- Transfer   of   Power   to   Fringe-Area
                                        Customers.

                  Service Schedule G -- Parker Power Interchange.

                  Service Schedule H -- Coordination     of      Interconnecting
                                        Transmission Circuits.

are approved this 29th day of February, 1956.


                                                       [Illegible]
                                              ----------------------------------
                                                Secretary of the Interior
                                                of the United States of America