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                      PUBLIC SERVICE COMPANY OF NEW MEXICO

                                       TO

                            THE CHASE MANHATTAN BANK

                                     Trustee


                                 --------------


                          FIRST SUPPLEMENTAL INDENTURE

                           Dated as of March 11, 1998

                                       To

                                    INDENTURE


                           Dated as of March 11, 1998


                                 --------------

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               (Creating Seven Series of Farmington Senior Notes)




63036183.02






         FIRST  SUPPLEMENTAL  INDENTURE,  dated as of March  11,  1998,  between
PUBLIC SERVICE COMPANY OF NEW MEXICO,  a New Mexico  corporation  duly organized
and  existing  under  the laws of the State of New  Mexico  (herein  called  the
"Company"),  having its principal  office at Alvarado Square,  Albuquerque,  New
Mexico 87158, and THE CHASE MANHATTAN BANK, a New York banking  corporation,  as
Trustee (herein called the "Trustee")  under the Indenture dated as of March 11,
1998 between the Company and the Trustee (the "Indenture").

                             RECITALS OF THE COMPANY

         The Company has executed and  delivered the Indenture to the Trustee to
provide for the issuance  from time to time of its senior  notes (the  "Notes"),
said Notes to be issued in one or more series as in the Indenture provided.

         Pursuant to the terms of the Indenture,  the Company desires to provide
for  establishment of seven new series of its Notes to be respectively  known as
set forth under the column entitled,  "Series of Farmington  Notes" in Exhibit A
hereto  (collectively,  the "Farmington  Notes"), the form and substance of such
Farmington  Notes and the terms,  provisions,  and conditions  thereof to be set
forth as provided in the Indenture and this First Supplemental Indenture.

         The City of  Farmington,  in the  County of San Juan,  an  incorporated
municipality, a body politic and corporate,  existing under the constitution and
laws of the State of New Mexico  (together with its successors and assigns,  the
"City") has issued seven series of its Pollution Control Revenue Refunding Bonds
(Public  Service  Company of New  Mexico  San Juan  Project or San Juan and Four
Corners Projects)  (collectively,  the "Refunding Bonds") as described under the
column entitled "Pollution Control Revenue Refunding Bonds" in Exhibit A hereto.
The City has appointed First Security Bank of New Mexico,  N.A.  (formerly named
First National Bank in  Alberquerque),  as trustee  (together with any successor
trustee under the Ordinances (as  hereinafter  defined),  each a "Refunding Bond
Trustee"),  with respect to each series of Refunding  Bonds, all pursuant to and
as more  particularly  set forth in the  Ordinance and  supplements  and, to the
extent  applicable,  amendments  thereto,  relating to such series of  Refunding
Bonds  described  under the column  entitled  "City of Farmington  Ordinance" in
Exhibit A hereto adopted by the City (collectively the "Ordinances").

         The  Company  by  the  seven  Guaranty  Agreements   (collectively  the
"Guaranties" and individually, a "Guaranty") described under the column entitled
"Guaranties  and First  Supplemental  Guaranties"  in Exhibit A hereto  related,
respectively,  to the seven series of Refunding  Bonds,  each by and between the
Company and the  applicable  Refunding Bond Trustee,  guaranteed  payment of the
principal  of and  interest  on,  and the  Purchase  Price  (as  defined  in the
Ordinances)  of, the Refunding  Bonds (the  "Guaranteed  Amounts").  The Company
issued certain of its First Mortgage Bonds ("First  Mortgage Bonds") pursuant to
the  Company's  Indenture of Mortgage and Deed of Trust dated as of June 1, 1947
to The  Bank  of  New  York  (formerly  Irving  Trust  Company)  and  indentures
supplemental thereto as security for the performance of the Company's obligation
under the Guaranties to pay the respective Guaranteed Amounts.


                                       1


         Pursuant  to each  Ordinance  and each  supplement  (collectively,  the
"First  Supplemental  Guaranties"),  to  each  of the  corresponding  Guaranties
between the Company and the Refunding Bond Trustee,  each such supplement  dated
as of March 11, 1998 and described  under the column  entitled,  "Guaranties and
First Supplemental Guaranties" in Exhibit A hereto, the First Mortgage Bonds are
being  exchanged  for  the  Farmington  Notes  to be  issued  under  this  First
Supplemental Indenture.

         Each of the seven new series of Farmington  Notes will relate to one of
the seven  series of  Refunding  Bonds  and will be issued  (x) in an  aggregate
principal amount equal to the aggregate  principal amount of the Refunding Bonds
of such series, maturing on such dates that upon the stated maturity date of the
Refunding  Bonds of such series a corresponding  principal  amount of Farmington
Notes of such  series  shall  mature,  (y) bearing  interest  (but only from the
Initial  Interest  Accrual Date, if any,  determined in accordance  with Section
1.03  below) at the same  interest  rate  borne by the  Refunding  Bonds of such
series and (z) be subject to  redemption  prior to maturity at the time,  in the
amount, and at the same redemption premium, if any, borne by the Refunding Bonds
of such  series.  Each  series of  Farmington  Notes  will be  delivered  to the
corresponding  Refunding  Bond Trustee,  as security for the  performance of the
Company's  obligation under the related  Guaranty to pay the Guaranteed  Amounts
under such Guaranty.

         All things necessary to make this First Supplemental  Indenture a valid
agreement of the Company, and to make the Farmington Notes, when executed by the
Company and authenticated and delivered by the Trustee, the valid obligations of
the Company, have been done.

  NOW, THEREFORE, THIS FIRST SUPPLEMENTAL INDENTURE WITNESSETH:

         For and in  consideration  of the  premises and the  acceptance  of the
Farmington  Notes by the  corresponding  Refunding  Bond  Trustee as  collateral
security  for the  related  series of  Refunding  Bonds,  and for the purpose of
setting  forth,  as provided in the  Indenture,  the form and  substance  of the
Farmington  Notes and the  terms,  provisions,  and  conditions  thereof,  it is
mutually agreed,  for the equal and proportionate  benefit of all Holders of the
Farmington Notes, as follows:

                                   ARTICLE ONE
                         GENERAL TERMS AND CONDITIONS OF
                              THE FARMINGTON NOTES

         SECTION 1.01. There shall be and are hereby  authorized seven series of
Farmington Notes designated as follows:

         1. "6.40% Notes,  Series  F-1993-A,  Due August 15,  2023,"  limited in
aggregate principal amount to $100,000,000;

         2. "6.30% Notes,  Series  F-1996-A,  Due December 1, 2016,"  limited in
aggregate principal amount to $40,045,000;


                                       2


         3. "6.30% Notes,  Series  F-1996-B,  Due December 1, 2016,"  limited in
aggregate principal amount to $37,000,000;

         4.  "5.80%  Notes,  Series  F-1997-A,  Due April 1,  2022,"  limited in
aggregate principal amount to $40,000,000;

         5.  "5.80%  Notes,  Series  F-1997-B,  Due April 1,  2022,"  limited in
aggregate principal amount to $37,000,000;

         6.  "5.80%  Notes,  Series  F-1997-C,  Due April 1,  2022,"  limited in
aggregate principal amount to $23,000,000; and

         7. "6 3/8%  Notes,  Series  F-1997-D,  Due April 1,  2022,"  limited in
aggregate principal amount to $90,000,000.

         The aggregate principal amount of each series of Farmington Notes to be
authenticated  and delivered shall be the aggregate  principal  amount set forth
under the column entitled "Principal Amount" in Exhibit A hereto. Subject to the
provisions of Section 1.03 below,  the  Farmington  Notes shall bear no interest
until  an  Initial  Interest  Accrual  Date,  if any,  has  been  determined  in
accordance  with Section 1.03 below.  The Farmington  Notes shall mature and the
principal thereof shall be due and payable, together with all accrued and unpaid
interest  thereon,  on their  respective  Stated  Maturities set forth under the
column entitled "Stated Maturity of Principal" in Exhibit A hereto, and shall be
issued  in  the  form  of  registered   Farmington  Notes  without  coupons,  in
denominations  of  $1,000  and  any  integral  multiple  thereof.  Each  of  the
Farmington Notes shall be dated as of the date of its authentication.

         SECTION 1.02. The Farmington Notes shall be issued to and registered in
the name of the Refunding Bond Trustee under the applicable  Ordinance and shall
be  non-transferable,  except  as may be  required  to  effect  transfer  to any
successor trustee to the Refunding Bond Trustee under such Ordinance.  Principal
of, and premium, if any, and interest on the Farmington Notes will be payable at
the  office  or  agency of the  Company  in The City and State of New York.  The
Farmington  Notes shall be deemed fully paid,  and the obligation of the Company
thereunder  shall be  terminated,  to the extent and in the manner  provided  in
Section 1.05.

         SECTION  1.03.  Each of the seven series of  Farmington  Notes has been
issued to the corresponding  Refunding Bond Trustee to secure the obligations of
the Company under the related Guaranty to pay the Guaranteed  Amounts under such
Guaranty.

         In the event of  failure  by the  Company  to make any  payment  of any
Guaranteed  Amounts  when  and as  required  by  the  Company  under  any of the
Guaranties,  the related  series of Farmington  Notes shall bear interest at the
annual rate  applicable  to such  series as set forth under the column  entitled
"Interest  Rate" in Exhibit A hereto from the last day to which  interest on the
corresponding  series of  Refunding  Bonds  has been  paid in full  prior to the
failure of the Company to pay such  Guaranteed  Amounts  (such date being herein
defined as the "Initial Interest Accrual Date"), and interest at such rate shall
be payable on the date due with respect to such Refunding  Bonds,  commencing on
the first  Interest  Payment  Date  applicable  to such  series set forth in the
column entitled  "Interest Payment Date" in Exhibit A hereto ("Interest  Payment
Date") following the Initial Interest Accrual Date.



                                       3


         The Trustee may  conclusively  presume that no payments with respect to
interest on the Farmington Notes are due unless and until the Trustee shall have
received a written  certificate  from the  applicable  Refunding  Bond  Trustee,
signed by an authorized officer of such Refunding Bond Trustee,  certifying that
the  Company has failed to make a payment of any  Guaranteed  Amount when and as
required  to be made by it  under  any of the  Guaranties  and  specifying  such
Guaranty,  such  Guaranteed  Amount,  the interest  rate,  the Initial  Interest
Accrual  Date,  the  Interest  Payment  Date  and such  other  terms as shall be
applicable  to the payment of interest on the  applicable  series of  Farmington
Notes. The Trustee may rely and shall be fully protected in acting upon any such
certificate  and shall have no duty with  respect to the terms  specified in any
such  certificate  other  than to make  them  available  for  inspection  by the
Company.

         SECTION 1.04.  The Farmington  Notes shall be redeemed,  in whole or in
part, at the principal amount thereof plus any premium, and any accrued interest
from the Initial  Interest Accrual Date to the redemption date, if the Refunding
Bond Trustee notifies the Trustee in writing that Refunding Bonds are subject to
redemption as provided in Section 3.02 of the  Ordinances.  Any such notice must
be received by the Trustee no later than five days  (unless a shorter  period of
time is acceptable to the Trustee)  prior to any  redemption  date fixed for the
Refunding  Bonds to be redeemed and shall specify the  principal  amount of such
Refunding  Bonds  anticipated as of the date of such notice to be redeemed,  the
redemption  date,  the  redemption  premium,  if any,  and the amount of accrued
interest  anticipated  to be paid thereon.  In the event such notice is given to
the Trustee as  hereinabove  provided,  the  redemption  date of the  applicable
series of Farmington Notes shall be the date on which the  corresponding  series
of  Refunding  Bonds are to be  redeemed,  and on such date the said  Farmington
Notes shall be redeemed in the same principal amount as the corresponding series
of Refunding Bonds in fact redeemed, pursuant to Section 3.01 of the Ordinances.
The Company  shall deposit in trust with the Trustee on the  redemption  date an
amount of money  sufficient  to pay the principal  amount,  plus any premium and
accrued  interest,  if any, to the date fixed for  redemption on the  Farmington
Notes to be redeemed (the "Redemption Price").  Upon presentation to the Trustee
of any of the  Farmington  Notes by a Refunding  Bond Trustee for payment of the
Redemption  Price, such Farmington Notes so presented shall be redeemed and paid
in full.  However,  if,  in lieu of  presenting  the  Farmington  Notes  due for
redemption,  the Refunding Bond Trustee shall deliver such  Farmington  Notes to
the Trustee for cancellation,  then and in that event,  subject to Section 1.05,
such of the Farmington Notes so presented for cancellation shall be deemed fully
paid,  and if any moneys  shall have been  deposited  with the  Trustee for such
redemption,  then  such  moneys  shall  be  paid  over to the  Company,  and the
Farmington  Notes so  surrendered  shall be canceled in accordance  with Section
1.05.

         SECTION 1.05 Upon  surrender by a Refunding Bond Trustee or the Company
to the Trustee hereunder of any of the Farmington Notes for  cancellation,  such
notes shall be canceled by the Trustee and delivered to the Company and shall be
deemed fully paid and the obligations of the Company thereunder terminated.


                                       4


         SECTION  1.06 The  Farmington  Notes  shall be  defeasible  pursuant to
Section 13.02 and Section 13.03 of the Indenture.

                                   ARTICLE TWO
                            FORM OF FARMINGTON NOTES

         SECTION 2.01.  The  Farmington  Notes and the Trustee's  certificate of
authentication  to be endorsed  thereon are to be substantially in the following
form:

         Pursuant to Section 1.02 of the First  Supplemental  Indenture dated as
of March 11, 1998,  supplemental  to the Indenture,  dated as of March 11, 1998,
between Public Service  Company of New Mexico and The Chase  Manhattan  Bank, as
Trustee,  this  Note is  nontransferable,  except as may be  required  to effect
transfer to any  successor  trustee to the  Refunding  Bond  Trustee (as defined
herein).

                      PUBLIC SERVICE COMPANY OF NEW MEXICO
                  ____% Notes, Series ____,Due ________________

No.                                                           $
    -----------                                                ------------

         PUBLIC  SERVICE  COMPANY  OF  NEW  MEXICO,  a  New  Mexico  corporation
organized and existing  under the laws of the State of New Mexico (herein called
the  "Company"  which term  includes any  successor  Person under the  Indenture
hereinafter  referred to), for value  received,  hereby promises to pay to First
Security  Bank of New Mexico,  N.A.,  as Trustee under the Ordinance (as defined
herein) on  ___*_____  (unless  this Note shall  have been  called for  previous
redemption and provision made for the payment of the redemption  price thereof),
the  principal  sum of $*  ____________  and to pay  interest  thereon  from the
Initial Interest Accrual Date (as defined herein) to the date of payment of this
Note at the rate of *_______%  per annum payable on the first  Interest  Payment
Date of *______ and *_______ following the Initial Interest Accrual Date.

         Payment of the principal of, and premium, if any, and any such interest
on this Note will be made at the office or agency of the Company  maintained for
that  purpose in The City of New York,  in such coin or  currency  of the United
States of  America as at the time of  payment  is legal  tender  for  payment of
public and private debts.

         This  Note is one of a duly  authorized  issue of  senior  notes of the
Company  (herein  called  the  "Notes"),  issued and to be issued in one or more
series  under an  Indenture,  dated as of March  11,  1998  (herein  called  the
"Indenture",  which  term  shall  have  the  meaning  assigned  to  it  in  such
instrument),  between  the  Company  and The Chase  Manhattan  Bank,  as Trustee
(herein  called the "Trustee",  which term includes any successor  trustee under
the Indenture), and reference is hereby made to the Indenture for a statement of
the respective rights,  limitations of rights,  duties and immunities thereunder
of the  Company,  the Trustee and the Holders of the Notes and of the terms upon
which the Notes are, and are to be, authenticated and delivered, to all of which
the Holder,  by  accepting  this Note,  assents.  This Note is one of the series
designated  on the  face  hereof,  limited  in  aggregate  principal  amount  to
$*............

- --------
 * Insert as appropriate for each series of Farmington  Notes, the designation,
principal  amount,  Interest Rate,  Stated Maturities of Principal and Interest,
Interest Payment Dates and other particulars  specified in Exhibit A hereto with
respect to such series.


                                       5


         The Indenture permits, with certain exceptions as therein provided, the
amendment  thereof and the  modification  of the rights and  obligations  of the
Company and the rights of the Holders of the Notes of each series to be affected
under the  Indenture at any time by the Company and the Trustee with the consent
of the  Holders  of a  majority  in  principal  amount  of the Notes at the time
Outstanding  of  each  series  to  be  affected.  The  Indenture  also  contains
provisions  permitting the Holders of specified  percentages in principal amount
of the Notes of each series at the time Outstanding, on behalf of the Holders of
all Notes of such  series,  to waive  compliance  by the  Company  with  certain
provisions  of the  Indenture  and to waive  certain  past  defaults  under  the
Indenture  and  their  consequences,  provided,  however,  that if any such past
default  affects  more than one series of Notes,  the  Holders of a majority  in
aggregate  principal  amount  of  the  Outstanding  Notes  of all  such  series,
considered as one class,  shall have the right to waive such past  default,  and
not the Holders of the Notes of any one such series.  Any such consent or waiver
by the Holder of this Note shall be conclusive  and binding upon such Holder and
upon  all  future  Holders  of  this  Note  and  of any  Note  issued  upon  the
registration  of  transfer  hereof or in  exchange  herefor  or in lieu  hereof,
whether or not notation of such consent or waiver is made upon this Note.

         As provided  in and subject to the  provisions  of the  Indenture,  the
Holder of this Note shall not have the right to institute  any  proceeding  with
respect to the Indenture or for the  appointment of a receiver or trustee or for
any other remedy thereunder,  unless such Holder shall have previously given the
Trustee  written  notice of a  continuing  Event of Default  with respect to the
Notes of this  series,  the  Holders  of not less than a majority  in  aggregate
principal  amount of the Notes of all series at the time  Outstanding in respect
of which an Event of Default shall have occurred and be  continuing,  considered
as one  class,  shall have made  written  request  to the  Trustee to  institute
proceedings  in respect of such Event of  Default  as Trustee  and  offered  the
Trustee reasonable  indemnity,  and the Trustee shall not have received from the
Holders of a  majority  in  principal  amount of Notes of all series at the time
Outstanding  in respect of which an Event of Default  shall have occurred and be
continuing, considered as one class, a direction inconsistent with such request,
and shall  have  failed to  institute  any such  proceeding,  for 60 days  after
receipt of such notice, request and offer of indemnity.  The foregoing shall not
apply to any suit  instituted by the Holder of this Note for the  enforcement of
any payment of principal  hereof or interest  hereon on or after the  respective
due dates expressed herein.

         No reference  herein to the  Indenture and no provision of this Note or
of the Indenture  shall alter or impair the obligation of the Company,  which is
absolute and unconditional, to pay the principal of and any premium and interest
on this Note at the times,  place and rate, and in the coin or currency,  herein
prescribed.


                                       6


         The Notes of this series have been issued to First Security Bank of New
Mexico,  N.A.,  Albuquerque,   New  Mexico,  as  trustee  (the  "Refunding  Bond
Trustee"),  under  Ordinance  No. *____ adopted by the City of  Farmington,  New
Mexico (the "City"),  on  *_________________,  as supplemented by Resolution No.
____________ adopted by the City on *_______________  [and amended by Amendatory
Ordinance  No.  _________  adopted  by the  City on  *_________________]  and as
supplemented  [and  amended] by  [Amendatory  and]  Supplemental  Ordinance  No.
_*__________  adopted by the City on  February  10,  1998  (collectively,  as so
supplemented  and  amended,  the  "Ordinance"),  to secure the  guarantee by the
Company under a Guaranty Agreement dated as of *____ between the Company and the
Refunding  Bond  Trustee  and under a First  Supplement  to  *________  Guaranty
Agreement  dated as of *____ between the Company and the Refunding  Bond Trustee
relating to the Refunding Bonds  (collectively,  the "Guaranty"),  of payment of
the  principal of and interest due (the  "Guaranteed  Amounts") on the Pollution
Control Revenue Refunding Bonds,  199*___ Series *___ (Public Service Company of
New Mexico [San Juan Project] [San Juan and Four Corners  Projects]),  issued by
the City under the Ordinance (the "Refunding Bonds").

         In the event of  failure  by the  Company  to make any  payment  of any
Guaranteed Amount when and as required to be made by it under the Guaranty, this
Note shall bear interest from the last date to which  interest on such Refunding
Bonds has been paid in full  prior to the  failure  of the  Company  to pay such
Guaranteed  Amount  (such date being  herein  defined as the  "Initial  Interest
Accrual  Date"),  at the rate of  *________%  per annum  payable on the  [first]
[fifteenth] day of *__________ and the [first][fifteenth] day of *___________ of
each year,  commencing on the first Interest  Payment Date following the Initial
Interest Accrual Date.

         The Trustee may  conclusively  presume that no payments with respect to
interest on the Notes of this series are due unless and until the Trustee  shall
have received a written certificate from the Refunding Bond Trustee or successor
trustee under the  Ordinance,  signed by an authorized  officer of the Refunding
Bond Trustee or such successor  trustee,  certifying that the Company has failed
to make a payment of any Guaranteed Amount when and as required to be made by it
under the Guaranty and specifying such Guaranteed  Amount,  the Initial Interest
Accrual  Date and such  other  matters,  if any,  as shall be  pertinent  to the
payment of interest on the Notes of this series.  The Trustee may rely and shall
be fully  protected in acting upon any such  certificate  and shall have no duty
with respect to the matters specified in any such certificate other than to make
it available for inspection by the Company.

         Upon the surrender for cancellation,  at any time or from time to time,
of Notes of this series by the Refunding Bond Trustee,  successor  trustee under
the Ordinance,  or the Company to the Trustee, the Notes so surrendered shall be
deemed  fully  paid  and the  obligations  of the  Company  thereunder  shall be
terminated, and such Notes shall be canceled by the Trustee and delivered to the
Company.

         This Note is nontransferable except to effect transfer to any successor
trustee to the Refunding Bond Trustee,  any such transfer to be made as provided
in the Indenture and subject to certain  limitations  therein set forth,  by the
registration  of transfer of this Note in the Note  Register,  upon surrender of
this Note for registration of transfer at the office or agency of the Company in
any place where the  principal  of and any premium and interest on this Note are
payable, duly endorsed by, or accompanied by a written instrument of transfer in
form  satisfactory  to the Company and the Note  Registrar duly executed by, the
Holder hereof or his attorney duly  authorized in writing,  and thereupon one or
more new Notes of this series and of like tenor, of authorized denominations and
for the  same  aggregate  principal  amount,  will be  issued  to the  successor
Refunding Bond Trustee.


                                       7


         If an Event of Default with respect to Notes of this series shall occur
and be continuing, the principal of the Notes of this series may be declared due
and payable in the manner and with the effect provided in the Indenture.

         No  recourse  shall  be had  for the  payment  of the  principal  of or
premium, if any, or interest,  if any, on any Notes, or any part thereof, or for
any claim based thereon or otherwise in respect thereof,  or of the indebtedness
represented  thereby,  or upon any obligation,  covenant or agreement under this
Indenture, against any incorporator, stockholder, employee, officer or director,
as such,  past,  present  or  future of the  Company  or of any  predecessor  or
successor  corporation  (either directly or through the Company or a predecessor
or successor  corporation),  whether by virtue of any constitutional  provision,
statute or rule of law, or by the  enforcement  of any  assessment or penalty or
otherwise;  it being expressly agreed and understood that this Indenture and all
Notes  are  solely  corporate  obligations,   and  that  no  personal  liability
whatsoever  shall attach to, or be incurred by, any  incorporator,  stockholder,
employee, officer or director, past, present or future, of the Company or of any
predecessor  or  successor  corporation,  because  of  the  indebtedness  hereby
authorized  or  under  or by  reason  of any of the  obligations,  covenants  or
agreements  contained in this  Indenture or in any of the Notes or to be implied
herefrom or therefrom,  and that any such personal liability is hereby expressly
waived and released as a condition of, and as part of the consideration for, the
execution of this Indenture and the issuance of the Notes.

         The Notes of this series are issuable only in  registered  form without
coupons  in  denominations  of $1,000  and any  integral  multiple  thereof.  As
provided in the Indenture and subject to certain  limitations therein set forth,
Notes of this series are exchangeable  for a like aggregate  principal amount of
Notes of this series and of like tenor of a different  authorized  denomination,
as requested by the Holder surrendering the same.

         No service charge shall be made for any such  registration  of transfer
or exchange,  but the Company may require  payment of a sum  sufficient to cover
any tax or other governmental charge payable in connection therewith.

         Prior to due presentment of this Note for registration of transfer, the
Company,  the  Trustee and any agent of the Company or the Trustee may treat the
Person in whose  name  this  Note is  registered  as the  owner  hereof  for all
purposes,  whether or not this Note be overdue,  and neither  the  Company,  the
Trustee nor any such agent shall be affected by notice to the contrary.

         The Notes of this series shall be  redeemable  as provided in the First
Supplemental  Indenture,  dated  as of  March  11,  1998,  supplemental  to  the
Indenture.


                                       8


         All terms used in this Note which are  defined in the  Indenture  shall
have the meanings assigned to them in the Indenture.

         Unless the  certificate of  authentication  hereon has been executed by
the  Trustee  referred  to below by manual  signature,  this  Note  shall not be
entitled to any benefit under the  Indenture or be valid or  obligatory  for any
purpose.

         IN WITNESS  WHEREOF,  the Company has caused this instrument to be duly
executed under its corporate seal.

Dated:
       ---------------------
                                        PUBLIC SERVICE COMPANY
                                        OF NEW MEXICO


                                        By
                                           --------------------------
                                                 [TITLE]

Attest:


- ----------------------------


                         CERTIFICATION OF AUTHENTICATION

         This is one of the Notes of the series  designated  therein referred to
in the within-mentioned Indenture.

Dated:
                                        THE CHASE MANHATTAN BANK, as Trustee


                                        By
                                           -------------------------- 
                                                 Authorized Officer


                                       9


                                  ARTICLE THREE
                       ORIGINAL ISSUE OF FARMINGTON NOTES

         SECTION 3.01. The Farmington Notes of the seven series set forth in the
column entitled "Series of Farmington Notes" in the respective principal amounts
thereof  set forth  under the  column  entitled  Principal  Amount" in Exhibit A
hereto , may, upon execution of this First Supplemental  Indenture, or from time
to time  thereafter,  be  executed  on behalf of the  Company by any  officer or
employee  authorized to do so by a Board  Resolution,  under its corporate  seal
affixed thereto or reproduced thereon attested by its Secretary or by one of its
Assistant  Secretaries and delivered to the Trustee for authentication,  and the
Trustee  shall  thereupon  authenticate  and  deliver  said  Farmington  Notesin
accordance with a Company Order delivered to the Trustee by the Company.

                                  ARTICLE FOUR
                           PAYING AGENT AND REGISTRAR

         SECTION  4.01.  The Chase  Manhattan  Bank will be the Paying Agent and
Note Registrar for the Farmington Notes.

                                  ARTICLE FIVE
                                SUNDRY PROVISIONS

         SECTION 5.01. The Company  hereby  covenants that so long as any of the
Farmington  Notes shall remain  outstanding,  the Company  shall  deliver to the
Trustee as soon as available copies  (certified by an officer or employee of the
Company  to be true)  of the  Ordinances,  the  corresponding  Installment  Sale
Agreement or Amended and Restated  Installment Sale Agreement (as defined in the
Ordinances),  the  Guaranties  and  copies  of any  supplements,  amendments  or
replacements thereto,  together with such other documents and instruments as the
Trustee  may  reasonably  request  from  time  to time in  connection  with  the
transactions  contemplated  hereby. The Trustee shall have no duty to examine or
take any other  action with  respect to any such  documents  or  instruments  so
received  by it,  other  than to retain  in its  files  any of same  which it so
receives and to make same available for inspection  during normal business hours
by any owner of the Farmington Notes.

         SECTION  5.02.  Except as  otherwise  expressly  provided in this First
Supplemental  Indenture or in the form of Farmington Notes or otherwise  clearly
required by the context hereof or thereof, all terms used herein or in said form
of the Farmington Notes that are defined in the Indenture shall have the several
meanings respectively assigned to them thereby.

         SECTION 5.03. The Indenture, as supplemented by this First Supplemental
Indenture,   is  in  all  respects  ratified  and  confirmed,   and  this  First
Supplemental  Indenture  shall be deemed part of the Indenture in the manner and
to the extent herein and therein provided.


                                       10


         SECTION 5.04. The Trustee  hereby  accepts the trusts herein  declared,
provided, created,  supplemented, or amended and agrees to perform the same upon
the terms and  conditions  herein and in the  Indenture,  set forth and upon the
following terms and conditions:

         The Trustee shall not be responsible in any manner whatsoever for or in
         respect of the  validity  or  sufficiency  of this  First  Supplemental
         Indenture or for or in respect of the recitals contained herein, all of
         which  recitals are made by the Company  solely.  In general,  each and
         every term and condition contained in Article VI of the Indenture shall
         apply to and form part of this First  Supplemental  Indenture  with the
         same force and effect as if the same were herein set forth in full with
         such  omissions,   variations,  and  insertions,  if  any,  as  may  be
         appropriate  to make the same conform to the  provisions  of this First
         Supplemental Indenture.

         To the extent  permitted by Section 6.01 of the Indenture,  and without
         limitation of Section 6.03 of the  Indenture,  the Trustee may rely and
         shall  be  protected  in  acting  upon  any  resolution,   certificate,
         statement,  instrument,  opinion,  report, notice, request,  direction,
         consent, order, bond, debenture,  note, other evidence of indebtedness,
         or  other  paper  or  document  (including,   without  limitation,  the
         Ordinances,  the Guaranties,  the First Supplemental Guaranties, or any
         notice,  certificate, or other document provided for in the Ordinances,
         the  Guaranties,  the  First  Supplemental  Guaranties  or  this  First
         Supplemental  Indenture)  believed  by the Trustee to be genuine and to
         have been signed or presented by the proper party or parties.

         SECTION  5.05.  This  instrument  may  be  executed  in any  number  of
counterparts,  each of which so executed shall be deemed to be an original,  but
all such counterparts shall together constitute but one and the same instrument.


                                       11



         IN  WITNESS  WHEREOF,   the  parties  hereto  have  caused  this  First
Supplemental,  Indenture to be duly  executed,  and their  respective  corporate
seals to be  hereunto  affixed  and  attested,  all as of the day and year first
above written.

                                        PUBLIC SERVICE COMPANY OF NEW MEXICO

                                        By:
                                            --------------------------------
                                                 M.H. Maerki
                                                 Senior Vice President
                                                 and Chief Financial Officer
Attest:


- --------------------
      Secretary
                                        THE CHASE MANHATTAN BANK, as Trustee

                                        By:
                                            --------------------------------
                                                 T.J. Foley
                                                 Vice President
Attest:


- --------------------
Senior Trust Officer


STATE OF NEW MEXICO   )
                      ) ss.:
COUNTY OF BERNALILLO  )

         On the ____ day of March,  1998 before me personally came M.H.  Maerki,
to me known,  who, being by me duly sworn,  did depose and say that he is Senior
Vice  President and Chief  Financial  Officer of Public  Service  Company of New
Mexico,  one of the  corporations  described in and which executed the foregoing
instrument; that he knows the seal of said corporation; that the seal affixed to
said  instrument is such corporate  seal; that it was so affixed by authority of
the Board of Directors of said corporation;  and that he signed his name thereto
by like authority.


                                               ----------------------------
                                               Notary Public

                                               My Commission Expires:

                                               ----------------------------

                                       12




STATE OF NEW YORK   )
                    ) ss.:
COUNTY OF NEW YORK  )

         On the 11th day of March,  1998,  before me personally came T.J. Foley,
to me known,  who,  being by me duly  sworn,  did depose and say that he is Vice
President of The Chase Manhattan Bank, one of the corporations  described in and
which  executed  the  foregoing  instrument;  that  he  knows  the  seal of said
corporation;  that the seal affixed to said  instrument is such corporate  seal;
that  it was so  affixed  by  authority  of  the  Board  of  Directors  of  said
corporation; and that he signed his name thereto by like authority.

                             

                                               ----------------------------
                                               Notary Public


50022


                                       13



                                       EXHIBIT A - DESCRIPTION OF 7 SERIES OF FARMINGTON NOTES
                                                 SAN JUAN AND FOUR CORNERS PROJECTS

                                                                                                                       Guaranties   
                                Series of                                             Interest       City of            and First   
       Pollution Control       Farmington     Principal    Stated Maturity  Interest  Payment      Farmington          Supplemental
    Revenue Refunding Bonds       Notes         Amount       of Principal     Rate     Dates        Ordinance          Guaranties
    -----------------------  --------------   ---------    ---------------  --------  --------     ----------          ------------
                                                                                            

1.  $100,000,000 City of    6.40% Notes,     $100,000,000 August 15,        6.40%   February 15 Ordinance No.       Guaranty Agree- 
    Farmington, New         Series F-1993-A,              2023                      August 15   93-995 adopted      ment dated      
    Mexico, 6.40% Pollu-    Due August 15,                                                      Aug. 24, 1993 as    August 15, 1993;
    tion Control Revenue    2023                                                                supplemented by     First Supple-   
    Refunding Bonds, 1993                                                                       Resolution No.      ment to 1993A   
    Series A (Public                                                                            93-748 adopted      Guaranty
    Service Company of                                                                          Aug. 24, 1993 and   Agreement dated
    New Mexico San Juan                                                                         as supplemented by  as of March 11,
    and Four Corners                                                                            Supplemental        1998.
    Projects).                                                                                  Ordinance No. 98-
                                                                                                1065 adopted on
                                                                                                February 10, 1998      


2.  $40,045,000 City of     6.30% Notes,      $40,045,000  December 1,      6.30%   June 1      Ordinance No.       Guaranty Agree- 
    Farmington, New Mexico  Series F-1996-A,               2016                     December 1  96-1049, adopted    ment dated      
    6.30% Pollution Control Due December 1,                                                     Nov. 19, 1996 as    December 1, 1996
    Control Revenue Re-     2016                                                                supplemented by     First Supple-   
    funding Bonds, 1995                                                                         Resolution No. 96-  ment to 1996A   
    Series A (Public Service                                                                    866 adopted Nov.    Guaranty Agree-
    Company of New Mexico                                                                       19, 1996 and as     ment dated as
    San Juan Project).                                                                          amended by Amenda-  of March 11,
                                                                                                tory Ordinance      1998.
                                                                                                No. 96-1050     
                                                                                                adopted on Nov.  
                                                                                                26, 1996 and as     
                                                                                                supplemented and    
                                                                                                amended by Amenda-  
                                                                                                tory and Supple-    
                                                                                                mental Ordinance No.
                                                                                                98-1066 adopted on  
                                                                                                February 10, 1998   

                                                                                                
3.  $37,000,000 City of     6.30% Notes,      $37,000,000  December 1,      6.30%   June 1      Ordinance No. 96-   Guaranty Agree- 
    Farmington, New Mexico  Series F-1996-B,               2016                     December 1  1049, adopted Nov.  ment dated      
    6.30% Pollution Con-    Due December 1,                                                     19, 1996 as sup-    December 1,1996 
    trol Revenue Refunding  2016                                                                plemented by        First Supplement
    Bonds, 1996 Series B                                                                        Resolution No. 96-  to 1996B        
    (Public Service Company                                                                     866 adopted Nov.19, Guaranty Agree-
    Mexico San Juan Project)                                                                    1996 and as amended ment dated as
                                                                                                by Amendatory Ordi- of March 11, 
                                                                                                nance No. 96-1050   1998
                                                                                                adopted on Nov. 26,
                                                                                                1996 and as supple-
                                                                                                mented No. 98-1066
                                                                                                adopted on February   
                                                                                                10, 1998

4.  $40,000,000 City of     5.80% Notes,      $40,000,000  April 1, 2022    5.80%   April 1     Ordinance No. 97-   Guaranty Agree- 
    Farmington, New Mexico  Series F-1997-A,                                        October 1   1052, adopted Jan.  ment dated      
    Pollution Control       Due April 1, 2022                                                   28, 1997 as supple- February 1,1997 
    Revenue Refunding                                                                           mented byResolution First supplement
    Bonds, 5.80% 1997                                                                           No. 97-870, adopted to 1997A        
    Series A (Public Ser-                                                                       Jan. 28, 1997 as    Guaranty Agree-
    vice Company of New                                                                         amended by Amenda-  ment dated as
    Mexico San Juan                                                                             tory Ordinance No.  of March 11,
    Project).                                                                                   97-1053 adopated    1998.
                                                                                                Feb. 11, 1997 and   
                                                                                                as supplemented by
                                                                                                Supplemental Ordi-
                                                                                                nance No. 98-1067
                                                                                                adopted on February
                                                                                                10, 1998

5.  $37,000,000 City of     5.80% Notes,       $37,000,000  April 1, 2022   5.80%   April 1     Ordinance No. 97-   Guaranty Agree- 
    Farmington, New Mexico  Series F-1997-B,                                        October 1   1052, adopted Jan.  ment dated      
    Pollution Control       Due April 1, 2022                                                   28, 1997 as supple- February 1, 1997
    Revenue Refunding                                                                           mented byResolution First Supplement
    Bonds 5.80% 1997                                                                            No. 97-870, adopted to 1997C      
    Series B (Public                                                                            Jan 28, 1997 as     Guaranty Agree-
    Service Company of                                                                          amended by Amenda-  ment dated as
    New Mexico San Juan                                                                         tory Ordinance No.  of March 11,
    Project).                                                                                   97-1053 adopted     1998.
                                                                                                Feb. 11, 1997 and 
                                                                                                as supplemented by
                                                                                                Supplemental Ordi-
                                                                                                nance No. 98-1067
                                                                                                adopted on February
                                                                                                10, 1998


6.  $23,000,000 City of     5.80% Notes,       $23,000,000  April 1, 2022    5.80%  April 1     Ordinance No. 97-   Guaranty Agree- 
    Farmington, New Mexico  Series F-1997-C,                                        October 1   1052, adopted Jan.  ment dated      
    Pollution Control       Due April 1, 2022                                                   28, 1997 as supple- February 1, 1997
    Revenue Refunding                                                                           mented byResolution First Supplement
    Bonds, 5.80% 1997                                                                           No. 97-870, adopted to 1997C        
    Series C (Public                                                                            Jan 28, 1997 as     Guaranty Agree- 
    Service Company of                                                                          amended by Amenda-  ment dated as   
    New Mexico San Juan                                                                         tory Ordinance No.  of March 11,    
    Project).                                                                                   97-1053 adopted     1998.           
                                                                                                Feb. 11, 1997 and                   
                                                                                                as supplemented by                  
                                                                                                Supplemental Ordi-                  
                                                                                                nance No. 98-1067                   
                                                                                                adopted on February                 
                                                                                                10, 1998                            
                                                                                                

7.  $90,000,000 City of     6 3/8% Notes,      $90,000,000  April 1, 2022   6.3/8%  April 1     Ordinance No. 97-   Guaranty Agree- 
    Farmington, New Mexico  Series F-1997-D,                                        October 1   1052, adopted Jan.  ment dated      
    6 3/8% Pollution        Due April 1, 2022                                                   28, 1997 as supple- February 1, 1997
    Control Revenue Re-                                                                         mented byResolution First Supplement
    funding Bonds, 1997                                                                         No. 97-870, adopted to 1997C        
    Series D (Public                                                                            Jan 28, 1997 as     Guaranty Agree- 
    Service Company of                                                                          amended by Amenda-  ment dated as   
    New Mexico San Juan                                                                         tory Ordinance No.  of March 11,    
    Project).                                                                                   97-1053 adopted     1998.           
                                                                                                Feb. 11, 1997 and                   
                                                                                                as supplemented by                  
                                                                                                Supplemental Ordi-                  
                                                                                                nance No. 98-1067                   
                                                                                                adopted on February                 
                                                                                                10, 1998