Document:

<PAGE>

                                                                     EXHIBIT 4.5

                         FORM OF SUPPLEMENTAL INDENTURE

                           (DATED AS OF [__________])

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

                       PUBLIC SERVICE COMPANY OF COLORADO

                                       TO

                      U.S. BANK TRUST NATIONAL ASSOCIATION,
                                                        AS TRUSTEE

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

                   CREATING AN ISSUE OF FIRST MORTGAGE BONDS,
                               COLLATERAL SERIES L

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

      (SUPPLEMENTAL TO INDENTURE DATED AS OF DECEMBER 1, 1939, AS AMENDED)

<PAGE>

                  SUPPLEMENTAL INDENTURE, dated as of [_________], between
PUBLIC SERVICE COMPANY OF COLORADO, a corporation organized and existing under
the laws of the State of Colorado (the "Company"), party of the first part, and
U.S. BANK TRUST NATIONAL ASSOCIATION (FORMERLY FIRST TRUST OF NEW YORK, NATIONAL
ASSOCIATION), a national banking association, as successor trustee (the
"Trustee") to Morgan Guaranty Trust Company of New York (formerly Guaranty Trust
Company of New York), party of the second part.

                  WHEREAS, the Company heretofore executed and delivered to the
Trustee its Indenture, dated as of December 1, 1939 (the "Principal Indenture"),
to secure its First Mortgage Bonds from time to time issued thereunder; and

                  WHEREAS, the Company has heretofore executed and delivered to
the Trustee the Supplemental Indentures referred to in Schedule A hereto for
certain purposes, including the creation of series of bonds, the subjection to
the lien of the Principal Indenture of property acquired after the execution and
delivery thereof, the amendment of certain provisions of the Principal Indenture
and the appointment of the successor Trustee; and

                  WHEREAS, the Principal Indenture as supplemented and amended
by all Supplemental Indentures heretofore executed by the Company and the
Trustee is hereinafter referred to as the "Indenture", and, unless the context
requires otherwise, references herein to Articles and Sections of the Indenture
shall be to Articles and Sections of the Principal Indenture as so amended; and

                  WHEREAS, the Company proposes to create a new series of First
Mortgage Bonds to be designated as First Mortgage Bonds, Collateral Series L
(the "Collateral Series L Bonds"), to be issued and delivered to the trustee
under the 1993 Mortgage (as hereinafter defined) as the basis for the
authentication and delivery under the 1993 Mortgage of a series of securities,
all as hereinafter provided, and to vary in certain respects the covenants and
provisions contained in Article V of the Indenture, to the extent that such
covenants and provisions apply to the Collateral Series L Bonds; and

                  WHEREAS, the Company, pursuant to the provisions of the
Indenture, has, by appropriate corporate action, duly resolved and determined to
execute this Supplemental Indenture for the purpose of providing for the
creation of the Collateral Series L Bonds and of specifying the form, provisions
and particulars thereof, as in the Indenture provided or permitted and of giving
to the Collateral Series L Bonds the protection and security of the Indenture;
and

                  WHEREAS, the Company represents that all acts and proceedings
required by law and by the charter and by-laws of the Company, including all
action requisite on the part of its shareholders, directors and officers,
necessary to make the Collateral Series L Bonds, when executed by the Company,
authenticated and delivered by the Trustee and duly issued, the valid, binding
and legal obligations of the Company, and to constitute the Principal Indenture
and all indentures supplemental thereto, including this Supplemental Indenture,
valid, binding and legal instruments for the security of the bonds of all
series, including the Collateral Series L Bonds, in accordance with the terms of
such bonds and such instruments, have been done, performed and fulfilled, and
the execution and delivery hereof have been in all respects duly authorized;

                                        1

<PAGE>

                  NOW, THEREFORE, THIS SUPPLEMENTAL INDENTURE WITNESSETH:

                  That Public Service Company of Colorado, the Company named in
the Indenture, in consideration of the premises and of One Dollar to it duly
paid by the Trustee at or before the ensealing and delivery of these presents,
the receipt whereof is hereby acknowledged, and in pursuance of the direction
and authority of the Board of Directors of the Company given at a meeting
thereof duly called and held, and in order to create the Collateral Series L
Bonds and to specify the form, terms and provisions thereof, and to secure the
payment of the principal of and premium, if any, and interest, if any, on all
bonds from time to time outstanding under the Indenture, including the
Collateral Series L Bonds, according to the terms of said bonds, and to secure
the performance and observance of all of the covenants and conditions contained
in the Indenture, has executed and delivered this Supplemental Indenture and has
granted, bargained, sold, warranted, aliened, remised, released, conveyed,
assigned, transferred, mortgaged, pledged, set over and confirmed unto U.S. Bank
Trust National Association, as Trustee, and its successor or successors in the
trust and its and their assigns forever;

                  TO HAVE AND TO HOLD all and singular the properties, rights,
privileges and franchises described in the Principal Indenture and in the
several Supplemental Indentures hereinabove referred to and owned by the Company
on the date of the execution and delivery hereof (other than property of a
character expressly excepted from the lien of the Indenture as therein set
forth) unto the Trustee and its successor or successors and assigns forever;

                  SUBJECT, HOWEVER, to permitted encumbrances as defined in the
Indenture;

                  IN TRUST, NEVERTHELESS, upon the terms and trusts set forth in
the Indenture, for the equal and proportionate benefit and security of all
present and future holders of the bonds and coupons issued and to be issued
under the Indenture, including the Collateral Series L Bonds, without
preference, priority or distinction as to lien (except as any sinking,
amortization, improvement or other fund established in accordance with the
provisions of the Indenture or any indenture supplemental thereto may afford
additional security for the bonds of any particular series) of any of said bonds
over any others thereof by reason of series, priority in the time of the issue
or negotiation thereof, or otherwise howsoever, except as provided in Section 2
of Article IV of the Indenture.

                                  ARTICLE ONE

            CREATION AND DESCRIPTION OF THE COLLATERAL SERIES L BONDS

                  SECTION 1. A new series of bonds to be issued under and
secured by the Indenture is hereby created, the bonds of such new series to be
designated First Mortgage Bonds, Collateral Series L. The Collateral Series L
Bonds shall be limited to an aggregate principal amount of Two Hundred Fifty
Million dollars ($250,000,000) (less the aggregate principal amount of First
Mortgage Bonds, Collateral Series K which remains outstanding), excluding any
Collateral Series L Bonds which may be authenticated and exchanged for or in
lieu of or in substitution for or on transfer of other Collateral Series L Bonds
pursuant to any provisions of the Indenture. The Collateral Series L Bonds shall
mature on March 1, 2013. The Collateral Series L Bonds shall not bear interest.

                                        2

<PAGE>

                  The principal of each Collateral Series L Bond shall be
payable, upon presentation thereof, at the office or agency of the Company in
the city in which the principal corporate trust office of the 1993 Mortgage
Trustee (as hereinafter defined) is located, in any coin or currency of the
United States of America which at the time of payment shall be legal tender for
the payment of public and private debts.

                  The Collateral Series L Bonds shall be issued and delivered by
the Company to U.S. Bank Trust National Association, as successor trustee under
the Indenture, dated as of October 1, 1993, as supplemented (the "1993
Mortgage"), of the Company to such successor trustee (the "1993 Mortgage
Trustee"), as the basis for the authentication and delivery under the 1993
Mortgage of a series of securities. As provided in the 1993 Mortgage, the
Collateral Series L Bonds will be registered in the name of the 1993 Mortgage
Trustee or its nominee and will be owned and held by the 1993 Mortgage Trustee,
subject to the provisions of the 1993 Mortgage, for the benefit of the holders
of all securities from time to time outstanding under the 1993 Mortgage, and the
Company shall have no interest therein.

                  Any payment by the Company under the 1993 Mortgage of the
principal of the securities which shall have been authenticated and delivered
under the 1993 Mortgage on the basis of the issuance and delivery to the 1993
Mortgage Trustee of Collateral Series L Bonds (other than by the application of
the proceeds of a payment in respect of such Collateral Series L Bonds) shall,
to the extent thereof, be deemed to satisfy and discharge the obligation of the
Company, if any, to make a payment of principal of such Collateral Series L
Bonds which is then due.

                  The Trustee may conclusively presume that the obligation of
the Company to pay the principal of the Collateral Series L Bonds as the same
shall become due and payable shall have been fully satisfied and discharged
unless and until it shall have received a written notice from the 1993 Mortgage
Trustee, signed by an authorized officer thereof, stating that the principal of
specified Collateral Series L Bonds has become due and payable and has not been
fully paid, and specifying the amount of funds required to make such payment.

                  Each Collateral Series L Bond shall be dated as of the date of
its authentication.

                  The Collateral Series L Bonds shall be issued as fully
registered bonds only, in denominations of $1,000 and multiples thereof.

                  The Collateral Series L Bonds shall be registerable and
exchangeable at the office or agency of the Company in the city in which the
principal corporate trust office of the 1993 Mortgage Trustee is located, in the
manner and upon the terms set forth in Section 5 of Article II of the Indenture;
provided, however, that the Collateral Series L Bonds shall not be transferrable
except to a successor trustee under the 1993 Mortgage. No service charge shall
be made for any exchange or transfer of any Collateral Series L Bond.

                  SECTION 2. The text of the Collateral Series L Bonds shall be
substantially in the form attached hereto as Exhibit A.

                                        3

<PAGE>

                  SECTION 3. The Collateral Series L Bonds may be executed by
the Company and delivered to the Trustee and, upon compliance with all
applicable provisions and requirements of the Indenture in respect thereof,
shall be authenticated by the Trustee and delivered (without awaiting the filing
or recording of this Supplemental Indenture) in accordance with the written
order or orders of the Company.

                                   ARTICLE TWO

                   REDEMPTION OF THE COLLATERAL SERIES L BONDS

                  SECTION 1. Each Collateral Series L Bond shall be redeemable
at the option of the Company in whole at any time, or in part from time to time,
prior to maturity, at a redemption price equal to 100% of the principal amount
thereof to be redeemed.

                  SECTION 2. The provisions of Sections 3, 4, 5, 6 and 7 of
Article V of the Indenture shall be applicable to the Collateral Series L Bonds,
except that (a) no publication of notice of redemption of the Collateral Series
L Bonds shall be required and (b) if less than all the Collateral Series L Bonds
are to be redeemed, the Collateral Series L Bonds to be redeemed shall be
selected in the principal amounts designated to the Trustee by the Company, and
except as such provisions may otherwise be inconsistent with the provisions of
this Article Two.

                  SECTION 3. The holder of each and every Collateral Series L
Bond hereby agrees to accept payment thereof prior to maturity on the terms and
conditions provided for in this Article Two.

                                  ARTICLE THREE

                         ACKNOWLEDGMENT OF RIGHT TO VOTE
                           OR CONSENT WITH RESPECT TO
                         CERTAIN AMENDMENTS TO INDENTURE

                  The Company hereby acknowledges the right of the holders of
the Collateral Series L Bonds to vote or consent with respect to any or all of
the modifications to the Indenture referred to in Article Three of the
Supplemental Indenture, dated as of March 1, 1980, irrespective of the fact that
the Bonds of the Second 1987 Series are no longer outstanding; provided,
however, that such acknowledgment shall not impair (a) the right of the Company
to make such modifications without the consent or other action of the holders of
the Bonds of the 2020 Series or the bonds of any other series subsequently
created under the Indenture with respect to which the Company has expressly
reserved such right or (b) the right of the Company to reserve the right to make
such modifications without the consent or other action of the holders of bonds
of one or more, or any or all, series created subsequent to the creation of the
Collateral Series L Bonds.

                                        4

<PAGE>

                                  ARTICLE FOUR

                                   THE TRUSTEE

                  The Trustee accepts the trusts created by this Supplemental
Indenture upon the terms and conditions set forth in the Indenture and this
Supplemental Indenture. The recitals in this Supplemental Indenture are made by
the Company only and not by the Trustee. Each and every term and condition
contained in Article XII of the Indenture shall apply to this Supplemental
Indenture with the same force and effect as if the same were herein set forth in
full, with such omissions, variations and modifications thereof as may be
appropriate to make the same conform to this Supplemental Indenture.

                                  ARTICLE FIVE

                            MISCELLANEOUS PROVISIONS

                  SECTION 1. Subject to the variations contained in Article Two
of this Supplemental Indenture, the Indenture is in all respects ratified and
confirmed and the Principal Indenture, this Supplemental Indenture and all other
indentures supplemental to the Principal Indenture shall be read, taken and
construed as one and the same instrument. Neither the execution of this
Supplemental Indenture nor anything herein contained shall be construed to
impair the lien of the Indenture on any of the properties subject thereto, and
such lien shall remain in full force and effect as security for all bonds now
outstanding or hereafter issued under the Indenture.

                  All covenants and provisions of the Indenture shall continue
in full force and effect and this Supplemental Indenture shall form part of the
Indenture.

                  SECTION 2. If the date for making any payment or the last date
for performance of any act or the exercising of any right, as provided in this
Supplemental Indenture, shall not be a Business Day (as defined in the 1993
Mortgage), such payment may be made or act performed or right exercised on the
next succeeding Business Day with the same force and effect as if done on the
nominal date provided in this Supplemental Indenture.

                  SECTION 3. The terms defined in the Indenture shall, for all
purposes of this Supplemental Indenture, have the meaning specified in the
Indenture except as set forth in Section 4 of this Article or otherwise set
forth in this Supplemental Indenture or unless the context clearly indicates
some other meaning to be intended.

                  SECTION 4. Any term defined in Section 303 of the Trust
Indenture Act of 1939, as amended, and not otherwise defined in the Indenture
shall, with respect to this Supplemental Indenture and the Collateral Series L
Bonds, have the meaning assigned to such term in Section 303 as in force on the
date of the execution of this Supplemental Indenture.

                  SECTION 5. This Supplemental Indenture may be executed in any
number of counterparts, and all of said counterparts executed and delivered,
each as an original, shall constitute but one and the same instrument.

                                        5

<PAGE>

                  IN WITNESS WHEREOF, Public Service Company of Colorado, party
hereto of the first part, has caused its corporate name to be hereunto affixed,
and this instrument to be signed by its President, an Executive Vice President,
a Senior Vice President or a Vice President, and its corporate seal to be
hereunto affixed and attested by its Secretary or an Assistant Secretary for and
in its behalf; and U.S. Bank Trust National Association, the party hereto of the
second part, in evidence of its acceptance of the trust hereby created, has
caused its corporate name to be hereunto affixed, and this instrument to be
signed and its corporate seal to be affixed by one of its Assistant Vice
Presidents and attested by one of its Trust Officers, for and in its behalf, all
as of the day and year first above written.

                                        PUBLIC SERVICE COMPANY OF
                                         COLORADO

            [COMPANY SEAL]              By: ____________________________________
                                            Name:
                                            Title:

ATTEST: _____________________________
        Name:
        Title:

STATE OF [        ]                )
                                       )  ss.:
CITY OF [         ]                )

                  On this [  ] day of [  ], 200[  ], before me, [  ], a duly
authorized Notary Public in and for said City in the State aforesaid, personally
appeared [  ] and [  ] to me known to be a [  ], respectively, of PUBLIC SERVICE
COMPANY OF COLORADO, a corporation organized and existing under the laws of the
State of Colorado, one of the corporations that executed the within and
foregoing instrument; and the said [  ] severally acknowledged the said
instrument to be the free and voluntary act and deed of said corporation, for
the uses and purposes therein mentioned, and on oath stated that they were
authorized to execute said instrument and that the seal affixed thereto is the
corporate seal of said corporation.

                  IN WITNESS WHEREOF, I have hereunto set my hand and affixed my
official seal the day and year first above written.

                                        ________________________________________
                                        Name:
                                        Notary Public, State of [___________]
                  [SEAL]                Commission Expires: [___________]

                                        6

<PAGE>

                                        U.S. BANK TRUST
                                          NATIONAL ASSOCIATION,
                                              as Trustee

                                        By: ____________________________________
                                            Name:
                                            Title:

ATTEST: _____________________________
        Name:
        Title:

STATE OF [       ]             )
                                   ) ss.:
CITY AND COUNTY OF [       ]       )

                  On this [  ] day of [  ], 200[  ], before me, [  ], a duly
authorized Notary Public in and for said City and County in the State aforesaid,
personally appeared [  ] and [  ] to me known to be an [  ], respectively, of
U.S. BANK TRUST NATIONAL ASSOCIATION, a national banking association, one of the
corporations that executed the within and foregoing instrument; and the said
[  ] severally acknowledged the said instrument to be the free and voluntary act
and deed of said corporation, for the uses and purposes therein mentioned, and
on oath stated that they were authorized to execute said instrument and that the
seal affixed thereto is the corporate seal of said corporation.

                  IN WITNESS WHEREOF, I have hereunto set my hand and affixed my
official seal the day and year first above written.

                                        ________________________________________
                                        Name:
                                        Notary Public, State of [  ]

                                        Commission Expires:

                                                          [SEAL]

                                       7

<PAGE>

                                                                       EXHIBIT A

                        FORM OF COLLATERAL SERIES L BOND

         THIS BOND IS NOT TRANSFERABLE EXCEPT TO A SUCCESSOR TRUSTEE UNDER THE
INDENTURE, DATED AS OF OCTOBER 1, 1993, AS SUPPLEMENTED, BETWEEN PUBLIC SERVICE
COMPANY OF COLORADO AND U.S. BANK TRUST NATIONAL ASSOCIATION (FORMERLY FIRST
TRUST OF NEW YORK, NATIONAL ASSOCIATION), AS SUCCESSOR TRUSTEE THEREUNDER.

                       PUBLIC SERVICE COMPANY OF COLORADO

                              FIRST MORTGAGE BOND,

                               Collateral Series L

                                    DUE 2013

REGISTERED                                                            REGISTERED

No.........                                                            $........

         FOR VALUE RECEIVED, PUBLIC SERVICE COMPANY OF COLORADO, a corporation
organized and existing under the laws of the State of Colorado (hereinafter
sometimes called the "Company"), promises to pay to U.S. Bank Trust National
Association (formerly known as First Trust of New York, National Association),
as successor trustee (the "1993 Mortgage Trustee") under the Indenture, dated as
of October 1, 1993 (the "1993 Mortgage"), of the Company, or registered assigns,

                                                                        Dollars
on March 1, 2013, at the office or agency of the Company in the city in which
the principal corporate trust office of the 1993 Mortgage Trustee is located.
This bond shall not bear interest. The principal of this bond shall be payable
in any coin or currency of the United States of America which at the time of
payment shall be legal tender for the payment of public and private debts.

         Any payment by the Company under the 1993 Mortgage of the principal of
securities which shall have been authenticated and delivered under the 1993
Mortgage on the basis of the issuance and delivery to the 1993 Mortgage Trustee
of this bond (the "1993 Mortgage Securities") (other than by the application of
the proceeds of a payment in respect of this bond) shall, to the extent thereof,
be deemed to satisfy and discharge the obligation of the Company, if any, to
make a payment of principal of this bond which is then due.

         This bond is one of an issue of bonds of the Company, issued and to be
issued in one or more series under and equally and ratably secured (except as
any sinking, amortization,

                                   Exhibit A-1

<PAGE>

improvement or other fund, established in accordance with the provisions of the
indenture hereinafter mentioned, may afford additional security for the bonds of
any particular series) by a certain indenture, dated as of December 1, 1939,
made by the Company to U.S. BANK TRUST NATIONAL ASSOCIATION (formerly First
Trust of New York, National Association), as successor trustee (hereinafter
called the "Trustee") to Morgan Guaranty Trust Company of New York (formerly
Guaranty Trust Company of New York), as amended and supplemented by several
indentures supplemental thereto, including the Supplemental Indenture dated as
of [  ] (said Indenture as amended and supplemented by said indentures
supplemental thereto being hereinafter called the "Indenture"), to which
Indenture reference is hereby made for a description of the property mortgaged,
the nature and extent of the security, the rights and limitations of rights of
the Company, the Trustee, and the holders of said bonds, under the Indenture,
and the terms and conditions upon which said bonds are secured, to all of the
provisions of which Indenture and of all indentures supplemental thereto in
respect of such security, including the provisions of the Indenture permitting
the issue of bonds of any series for property which, under the restrictions and
limitations therein specified, may be subject to liens prior to the lien of the
Indenture, the holder, by accepting this bond, assents. To the extent permitted
by and as provided in the Indenture, the rights and obligations of the Company
and of the holders of said bonds (including those pertaining to any sinking or
other fund) may be changed and modified, with the consent of the Company, by the
holders of at least 75% in aggregate principal amount of the bonds then
outstanding (excluding bonds disqualified from voting by reason of the Company's
interest therein as provided in the Indenture); provided, however, that without
the consent of the holder hereof no such modification or alteration shall be
made which will extend the time of payment of the principal of this bond or
reduce the principal amount hereof or effect any other modification of the terms
of payment of such principal or will reduce the percentage of bonds required for
the aforesaid actions under the Indenture. The Company has reserved the right to
amend the Indenture without any consent or other action by holders of any series
of bonds created after October 31, 1975 (including this series) so as to change
75% in the foregoing sentence to 60% and to change certain procedures relating
to bondholders' meetings. This bond is one of a series of bonds designated as
the First Mortgage Bonds, Collateral Series L, of the Company.

         This bond shall be redeemable at the option of the Company in whole at
any time, or in part from time to time, prior to maturity, at a redemption price
equal to 100% of the principal amount thereof to be redeemed.

         The principal of this bond may be declared or may become due before the
maturity hereof, on the conditions, in the manner and at the times set forth in
the Indenture, upon the happening of an event of default as therein provided.

         This bond is not transferable except to a successor trustee under the
1993 Mortgage, any such transfer to be made at the office or agency of the
Company in the city in which the principal corporate trust office of the 1993
Mortgage Trustee is located, upon surrender and cancellation of this bond, and
thereupon a new bond of this series of a like principal amount will be issued to
the transferee in exchange therefor, as provided in the Indenture. The Company,
the Trustee, any paying agent and any registrar may deem and treat the person in
whose name this bond is registered as the absolute owner hereof for the purpose
of receiving payment and for all other purposes. This bond, alone or with other
bonds of this series, may in like manner be exchanged

                                   Exhibit A-2

<PAGE>

at such office or agency for one or more new bonds of this series of the same
aggregate principal amount, all as provided in the Indenture. No service charge
shall be made to any holder of any bond of this series for any exchange or
transfer of bonds.

         No recourse under or upon any covenant or obligation of the Indenture,
or of any bonds thereby secured, or for any claim based thereon, or otherwise in
any manner in respect thereof, shall be had against any incorporator, subscriber
to the capital stock, shareholder, officer or director, as such, of the Company,
whether former, present or future, either directly, or indirectly through the
Company or the Trustee, by the enforcement of any subscription to capital stock,
assessment or otherwise, or by any legal or equitable proceeding by virtue of
any statute or otherwise (including, without limiting the generality of the
foregoing, any proceeding to enforce any claimed liability of shareholders of
the Company based upon any theory of disregarding the corporate entity of the
Company or upon any theory that the Company was acting as the agent or
instrumentality of the shareholders), any and all such liability of
incorporators, shareholders, subscribers, officers and directors, as such, being
released by the holder hereof, by the acceptance of this bond, and being
likewise waived and released by the terms of the Indenture under which this bond
is issued.

         This bond shall not be valid or become obligatory for any purpose until
the certificate of authentication endorsed hereon shall have been signed by U.S.
Bank Trust National Association, or its successor, as Trustee under the
Indenture.

         IN WITNESS WHEREOF, Public Service Company of Colorado has caused this
bond to be signed in its name by a Vice President and its corporate seal to be
affixed hereto and attested by its Secretary or an Assistant Secretary.

Dated:                                  PUBLIC SERVICE COMPANY OF
                                        COLORADO

                                        By: ____________________________________

ATTEST: ____________________________

                          CERTIFICATE OF AUTHENTICATION

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

Dated:                                  U.S. BANK TRUST
                                        NATIONAL ASSOCIATION,
                                                AS TRUSTEE

                                        By: ____________________________________
                                                              Authorized Officer

                                   Exhibit A-3

<PAGE>

                                                                      SCHEDULE A

                             SUPPLEMENTAL INDENTURES

<TABLE>
<CAPTION>
     DATE OF                                                                                     PRINCIPAL
  SUPPLEMENTAL                                                         PRINCIPAL                   AMOUNT
    INDENTURE                         SERIES OF BONDS                AMOUNT ISSUED              OUTSTANDING
    ---------                         ---------------               --------------              -----------
<S>                                <C>                             <C>                          <C>
March 14, 1941                              None                                --                   --
May 14, 1941                                None                                --                   --
April 28, 1942                              None                                --                   --
April 14, 1943                              None                                --                   --
April 27, 1944                              None                                --                   --
April 18, 1945                              None                                --                   --
April 23, 1946                              None                                --                   --
April 9, 1947                               None                                --                   --
June 1, 1947*                      2-7/8% Series due 1977          $    40,000,000                  None
April 1, 1948                               None                                --                   --
May 20, 1948                                None                                --                   --
October 1, 1948                    3-1/8% Series due 1978               10,000,000                  None
April 20, 1949                              None                                --                   --
April 24, 1950                              None                                --                   --
April 18, 1951                              None                                --                   --
October 1, 1951                    3-1/4% Series due 1981               15,000,000                  None
April 21, 1952                              None                                --                   --
December 1, 1952                            None                                --                   --
April 15, 1953                              None                                --                   --
April 19, 1954                              None                                --                   --
October 1, 1954*                   3-1/8% Series due 1984               20,000,000                  None
April 18, 1955                              None                                --                   --
April 24, 1956                              None                                --                   --
May 1, 1957*                       4-3/8% Series due 1987               30,000,000                  None
April 10, 1958                              None                                --                   --
May 1, 1959                        4-5/8% Series due 1989               20,000,000                  None
April 18, 1960                              None                                --                   --
April 19, 1961                              None                                --                   --
October 1, 1961                    4-1/2% Series due 1991               30,000,000                  None
March 1, 1962                      4-5/8% Series due 1992                8,800,000                  None
June 1, 1964                       4-1/2% Series due 1994               35,000,000                  None
May 1, 1966                        5-3/8% Series due 1996               35,000,000                  None
July 1, 1967*                      5-7/8% Series due 1997               35,000,000                  None
July 1, 1968*                      6-3/4% Series due 1998               25,000,000                  None
April 25, 1969                              None                                --                   --
</TABLE>

                                  Schedule A-1

<PAGE>

<TABLE>
<CAPTION>
      DATE OF                                                                                  PRINCIPAL
   SUPPLEMENTAL                                                         PRINCIPAL               AMOUNT
     INDENTURE                        SERIES OF BONDS                 AMOUNT ISSUED           OUTSTANDING
     ---------                        ---------------                 -------------           -----------
<S>                         <C>                                       <C>                     <C>
April 21, 1970                              None                                 --                --
September 1, 1970                  8-3/4% Series due 2000                35,000,000               None
February 1, 1971                   7-1/4% Series due 2001                40,000,000               None
August 1, 1972                     7-1/2% Series due 2002                50,000,000               None
June 1, 1973                       7-5/8% Series due 2003                50,000,000               None
March 1, 1974                    Pollution Control Series A              24,000,000               None
December 1, 1974                 Pollution Control Series B              50,000,000               None
October 1, 1975                    9-3/8% Series due 2005                50,000,000               None
April 28, 1976                              None                                 --                --

April 28, 1977                              None                                 --                --
November 1, 1977*                  8-1/4% Series due 2007                50,000,000               None
April 28, 1978                              None                                 --                --
October 1, 1978                    9-1/4% Series due 2008                50,000,000               None
October 1, 1979*                 Pollution Control Series C              50,000,000               None
March 1, 1980*                      15% Series due 1987                  50,000,000               None
April 28, 1981                              None                                 --                --
November 1, 1981*                Pollution Control Series D              27,380,000               None
December 1, 1981*                 16-1/4% Series due 2011                50,000,000               None
April 29, 1982                              None                                 --                --
May 1, 1983*                     Pollution Control Series E              42,000,000               None

April 30, 1984                              None                                 --                --
March 1, 1985*                      13% Series due 2015                  50,000,000               None
November 1, 1986*                Pollution Control Series F              27,250,000               None
May 1, 1987*                       8.95% Series due 1992                 75,000,000               None
July 1, 1990*                      9-7/8% Series due 2020                75,000,000               None
December 1, 1990*           Secured Medium-Term Notes, Series A         191,500,000**             None
March 1, 1992*                   8-1/8% Series due 2004 and             100,000,000           100,000,000
                                   8-3/4% Series due 2022               150,000,000           144,840,000
April 1, 1993*                   Pollution Control Series G              79,500,000            79,500,000
June 1, 1993*                    Pollution Control Series H              50,000,000            50,000,000
November 1, 1993*                   Collateral Series A                 134,500,000           134,500,000

January 1, 1994*              Collateral Series B due 2001 and          102,667,000               None
                                Collateral Series B due 2024            110,000,000           110,000,000
September 2, 1994                           None                                 --                --
(Appointment of
Successor Trustee)
May 1, 1996                         Collateral Series C                 125,000,000           125,000,000
</TABLE>

                                  Schedule A-2

<PAGE>

<TABLE>
<CAPTION>
      DATE OF                                                                                  PRINCIPAL
   SUPPLEMENTAL                                                         PRINCIPAL                AMOUNT
     INDENTURE                        SERIES OF BONDS                 AMOUNT ISSUED           OUTSTANDING
     ---------                        ---------------                 -------------           -----------
<S>                                 <C>                               <C>                     <C>
November 1, 1996                    Collateral Series D                 250,000,000           175,000,000
February 1, 1997                    Collateral Series E                 150,000,000               None
April 1, 1998                       Collateral Series F                 250,000,000               None
August 15, 2002                     Collateral Series G                  48,750,000            48,750,000
September 1, 2002                   Collateral Series H                 600,000,000               None
September 15, 2002                  Collateral Series I                 530,000,000               None
April 1, 2003                       Collateral Series J                 600,000,000           600,000,000
March 1, 2003                       Collateral Series K                 250,000,000           250,000,000
May 1, 2003                         Collateral Series M                 350,000,000           350,000,000
</TABLE>

-----------
*  Contains amendatory provisions

**  $200,000,000 authorized

                                  Schedule A-3<PAGE>

                                                                     EXHIBIT 4.9

                             PUBLIC SERVICE COMPANY
                                   OF COLORADO

                                       TO

                      U.S. BANK TRUST NATIONAL ASSOCIATION,

                                                            AS TRUSTEE

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

                          SUPPLEMENTAL INDENTURE NO. 14

                             Dated as of May 1, 2003

                          Supplemental to the Indenture
                           dated as of October 1, 1993

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

                  Establishing the Securities of Series No. 13,
    designated First Collateral Trust Bonds, Series No. 13 (Credit Agreement
                               Collateral Bonds)

<PAGE>

         SUPPLEMENTAL INDENTURE NO. 14, dated as of May 1, 2003, between PUBLIC
SERVICE COMPANY OF COLORADO, a corporation duly organized and existing under the
laws of the State of Colorado (hereinafter sometimes called the "Company"), and
U.S. BANK TRUST NATIONAL ASSOCIATION (FORMERLY FIRST TRUST OF NEW YORK, NATIONAL
ASSOCIATION), a national banking association, as successor trustee (hereinafter
sometimes called the "Trustee") to Morgan Guaranty Trust Company of New York
under the Indenture, dated as of October 1, 1993 (hereinafter called the
"Original Indenture"), as previously supplemented and as further supplemented by
this Supplemental Indenture No. 14. The Original Indenture and any and all
indentures and all other instruments supplemental thereto are hereinafter
sometimes collectively called the "Indenture".

                             RECITALS OF THE COMPANY

         The Original Indenture was authorized, executed and delivered by the
Company to provide for the issuance from time to time of its Securities (such
term and all other capitalized terms used herein without definition having the
meanings assigned to them in the Original Indenture), to be issued in one or
more series as contemplated therein, and to provide security for the payment of
the principal of and premium, if any, and interest, if any, on the Securities.

         The Company has heretofore executed and delivered to the Trustee the
Supplemental Indentures referred to in Schedule A hereto for the purpose of
establishing series of bonds and appointing the successor Trustee.

         The Company is entering into a Credit Agreement (as it may be amended,
supplemented, restated or otherwise modified from time to time, the "Credit
Agreement"), dated as of May 16, 2003, with Bank One, NA, as Administrative
Agent (the "Administrative Agent") and the several financial institutions and
other persons from time to time party thereto (collectively, the "Banks"),
pursuant to which the Banks have agreed to make advances, to issue or
participate in letters of credit and to grant certain other financial
accommodations to the Company up to an aggregate principal amount of Three
Hundred Fifty Million dollars ($350,000,000) (the "Credit Extensions"). The
Credit Agreement requires the Company to cause the Company's obligations to pay
the principal amount due under the Credit Agreement with respect to the Credit
Extensions and to fund the Cash Collateral Account (as defined in the Credit
Agreement) pursuant to Section 2.7(g) and/or 7.2(c) thereof (collectively, the
"Principal Obligations"), to be ratably secured with all indebtedness of the
Company under the Indenture, as a condition to, and as consideration for, the
obligation of the Banks to make the Credit Extensions in accordance with the
terms of the Credit Agreement.

         Pursuant to its obligations under the Credit Agreement, the Company now
desires to establish a series of Securities to be designated "First Collateral
Trust Bonds, Series No. 13 (Credit Agreement Collateral Bonds)", such series of
Securities to be hereinafter sometimes called "Series No. 13".

         The Company has duly authorized the execution and delivery of this
Supplemental Indenture No. 14 to establish the Securities of Series No. 13 and
has duly authorized the issuance of such Securities; and all acts necessary to
make this Supplemental Indenture No. 14 a valid agreement of the Company, and to
make the Securities of Series No. 13 valid obligations of the Company, have been
performed.

                                GRANTING CLAUSES

         NOW, THEREFORE, THIS SUPPLEMENTAL INDENTURE NO. 14 WITNESSETH, that, in
consideration of the premises, including, without limitation, the agreement of
the Banks to make Credit Extensions available to the Company in accordance with
the terms of the Credit Agreement, and in order to secure the payment of the
principal of and premium, if any, and interest, if any, on all Securities from
time to time Outstanding and the performance of the covenants contained therein
and in the

<PAGE>

Indenture and to declare the terms and conditions on which such Securities are
secured, the Company hereby grants, bargains, sells, releases, conveys, assigns,
transfers, mortgages, pledges, sets over and confirms to the Trustee, and grants
to the Trustee a security interest in, the following:

                              GRANTING CLAUSE FIRST

                  All right, title and interest of the Company, as of the date
         of the execution and delivery of this Supplemental Indenture No. 14, in
         and to property (other than Excepted Property), real, personal and
         mixed and wherever situated, in any case used or to be used in or in
         connection with the Electric Utility Business (whether or not such use
         is the sole use of such property), including without limitation (a) all
         lands, easements, servitudes, licenses, permits, rights of way and
         other rights and interests in or relating to real property used or to
         be used in or in connection with the Electric Utility Business or
         relating to the occupancy or use of such real property, subject
         however, to the exceptions and exclusions set forth in clause (a) of
         Granting Clause First of the Original Indenture; (b) all plants,
         generators, turbines, engines, boilers, fuel handling and
         transportation facilities, air and water pollution control and sewage
         and solid waste disposal facilities and other machinery and facilities
         for the generation of electric energy; (c) all switchyards, lines,
         towers, substations, transformers and other machinery and facilities
         for the transmission of electric energy; (d) all lines, poles,
         conduits, conductors, meters, regulators and other machinery and
         facilities for the distribution of electric energy; (e) all buildings,
         offices, warehouses and other structures used or to be used in or in
         connection with the Electric Utility Business; (f) all pipes, cables,
         insulators, ducts, tools, computers and other data processing and/or
         storage equipment and other equipment, apparatus and facilities used or
         to be used in or in connection with the Electric Utility Business; (g)
         any or all of the foregoing properties in the process of construction;
         and (h) all other property, of whatever kind and nature, ancillary to
         or otherwise used or to be used in conjunction with any or all of the
         foregoing or otherwise, directly or indirectly, in furtherance of the
         Electric Utility Business;

                             GRANTING CLAUSE SECOND

                  Subject to the applicable exceptions permitted by Section
         810(c), Section 1303 and Section 1305 of the Original Indenture, all
         property (other than Excepted Property) of the kind and nature
         described in Granting Clause First which may be hereafter acquired by
         the Company, it being the intention of the Company that all such
         property acquired by the Company after the date of the execution and
         delivery of this Supplemental Indenture No. 14 shall be as fully
         embraced within and subjected to the Lien hereof as if such property
         were owned by the Company as of the date of the execution and delivery
         of this Supplemental Indenture No. 14;

                             GRANTING CLAUSE FOURTH

                  All other property of whatever kind and nature subjected or
         required to be subjected to the Lien of the Indenture by any of the
         provisions thereof;

                                EXCEPTED PROPERTY

                  Expressly excepting and excluding, however, from the Lien and
         operation of the Indenture all Excepted Property of the Company,
         whether now owned or hereafter acquired;

                                        2

<PAGE>

         TO HAVE AND TO HOLD all such property, real, personal and mixed, unto
the Trustee, its successors in trust and their assigns forever;

         SUBJECT, HOWEVER, to (a) Liens existing at the date of the execution
and delivery of the Original Indenture (including, but not limited to, the Lien
of the PSCO 1939 Mortgage), (b) as to property acquired by the Company after the
date of the execution and delivery of the Original Indenture, Liens existing or
placed thereon at the time of the acquisition thereof (including, but not
limited to, the Lien of any Class A Mortgage and purchase money Liens), (c)
Retained Interests and (d) any other Permitted Liens, it being understood that,
with respect to any property which was at the date of execution and delivery of
the Original Indenture or thereafter became or hereafter becomes subject to the
Lien of any Class A Mortgage, the Lien of the Indenture shall at all times be
junior, subject and subordinate to the Lien of such Class A Mortgage;

         IN TRUST, NEVERTHELESS, for the equal and proportionate benefit and
security of the Holders from time to time of all Outstanding Securities without
any priority of any such Security over any other such Security;

         PROVIDED, HOWEVER, that the right, title and interest of the Trustee in
and to the Mortgaged Property shall cease, terminate and become void in
accordance with, and subject to the conditions set forth in, Article Nine of the
Original Indenture, and if, thereafter, the principal of and premium, if any,
and interest, if any, on the Securities shall have been paid to the Holders
thereof, or shall have been paid to the Company pursuant to Section 603 of the
Original Indenture, then and in that case the Indenture shall terminate, and the
Trustee shall execute and deliver to the Company such instruments as the Company
shall require to evidence such termination; otherwise the Indenture, and the
estate and rights thereby granted shall be and remain in full force and effect;
and

            THE PARTIES HEREBY FURTHER COVENANT AND AGREE as follows:

                                  ARTICLE ONE

                           SECURITIES OF SERIES NO. 13

         There are hereby established the Securities of Series No. 13. The
Securities of Series No. 13 shall have the terms and characteristics set forth
below (the lettered subdivisions set forth below corresponding to the lettered
subdivisions of Section 301 of the Original Indenture):

         (a)      the title of the Securities of such series shall be "First
         Collateral Trust Bonds, Series No. 13 (Credit Agreement Collateral
         Bonds)"; provided, however, that, at any time after the PSCO 1939
         Mortgage shall have been satisfied and discharged, the Company shall
         have the right, without any consent or other action by the Holders of
         such Securities, to change such title in such manner as shall be deemed
         by the Company to be appropriate to reflect such satisfaction and
         discharge, such change to be evidenced in an Officer's Certificate;

         (b)      the Securities of Series No. 13 shall be initially
         authenticated and delivered in the aggregate principal amount of
         $350,000,000;

         (c)      not applicable;

         (d)      the principal of the Securities of Series No. 13 shall be
         payable on May 14, 2004, the Stated Maturity.

                                        3

<PAGE>

         (e)      the Securities of Series No. 13 shall not bear interest;

         (f)      the Corporate Trust Office of U.S. Bank Trust National
         Association in New York, New York shall be the place at which (i) the
         principal of, premium, if any, and interest, if any, on the Securities
         of Series No. 13 shall be payable, (ii) registration of transfer of
         such Securities may be effected, (iii) exchanges of such Securities may
         be effected and (iv) notices and demands to or upon the Company in
         respect of such Securities and the Indenture may be served; and U.S.
         Bank Trust National Association shall be the Security Registrar for
         such Securities; provided, however, that the Company reserves the right
         to change, by one or more Officer's Certificates, any such place or the
         Security Registrar; and provided, further, that the Company reserves
         the right to designate, by one or more Officer's Certificates, its
         principal office in Denver, Colorado as any such place or itself as the
         Security Registrar;

         (g)      the Securities of Series No. 13 shall not be redeemable at the
         option of the Company prior to maturity, other than as set forth in the
         Indenture;

         (h)      upon the occurrence of an Event of Default (as defined in the
         Credit Agreement) pursuant to Section 7.1(a), (b) or (p) thereof or any
         other Event of Default under the Credit Agreement that results in the
         acceleration of any Principal Obligations thereunder, then the
         Securities of Series No. 13 shall be redeemable in whole or in part
         upon receipt by the Trustee and the Company of a written demand (a
         "Redemption Demand") from the Administrative Agent specifying a Demand
         Redemption Date (which may be the date of receipt by the Company of the
         Redemption Demand) stating that there has been such an Event of Default
         and demanding redemption of the Securities (a) to the extent of the
         principal amount of the accelerated Principal Obligations, and/or (b)
         in the case of an Event of Default arising under the Credit Agreement
         pursuant to Section 7.1(p), to the extent of the amount then required
         to be deposited pursuant to Section 2.7(g) and/or 7.2(c) of the Credit
         Agreement. The Securities of Series No. 13 shall be redeemed by the
         Company on the Demand Redemption Date at a redemption price equal to
         100% of the principal amount thereof to be redeemed; provided, however,
         to the extent the Company pays the principal amount of the Principal
         Obligations so accelerated and/or the amounts due pursuant to Section
         2.7(g) and/or 7.2(c) of the Credit Agreement, the Company's obligation
         to pay the redemption price of such Securities shall be deemed
         satisfied. Promptly after receipt of the redemption price, the
         Administrative Agent shall surrender the Securities of Series No. 13 to
         be redeemed to the Trustee. Upon the surrender of any Security which is
         to be redeemed only in part, the Company shall execute and the Trustee
         shall authenticate a new Security or Securities in an aggregate
         principal amount equal to and in exchange for the unredeemed portion of
         the principal of the Security so surrendered. If a Redemption Demand is
         rescinded by the Administrative Agent by written notice to the Trustee
         and the Company prior to the Demand Redemption Date, the Redemption
         Demand shall be automatically annulled; but no such rescission shall
         extend to or affect any subsequent Event of Default pursuant to Section
         7.1(a), (b) or (p) of the Credit Agreement or any other Event of
         Default under the Credit Agreement resulting in the acceleration of
         Principal Obligations under the Credit Agreement or impair any right
         consequent thereon;

         (i)      not applicable;

         (j)      not applicable;

                                        4

<PAGE>

         (k)      not applicable;

         (l)      not applicable;

         (m)      not applicable;

         (n)      not applicable;

         (o)      not applicable;

         (p)      not applicable;

         (q)      the Securities of Series No. 13 are to be registered in the
         name of Bank One, NA, as Administrative Agent. Such Securities shall
         not be transferable, nor shall any purported transfer be registered
         except to a successor to the Administrative Agent under the Credit
         Agreement upon delivery to the Trustee of a Company Request requesting
         such transfer; provided, however, that, if an Event of Default exists
         under the Credit Agreement, the Administrative Agent may submit a
         written notice of its successor directly to the Trustee;

         (r)      not applicable;

         (s)      no service charge shall be made for the transfer or exchange
         of the Securities of Series No. 13;

         (t)      not applicable;

         (u)      (i)      If the Company shall have caused the Company's
                  indebtedness in respect of any Securities of Series No. 13 to
                  have been satisfied and discharged prior to the Maturity of
                  such Securities, as provided in Section 901 of the Original
                  Indenture, the Company shall, promptly after the date of such
                  satisfaction and discharge, give a notice to each Person who
                  was a Holder of any of such Securities on such date stating
                  (A)(1) the aggregate principal amount of such Securities and
                  (2) the aggregate amount of any money (other than amounts, if
                  any, deposited in respect of accrued interest on such
                  Securities) and the aggregate principal amount of, the rate or
                  rates of interest on, and the aggregate fair market value of,
                  any Eligible Obligations deposited pursuant to Section 901 of
                  the Original Indenture with respect to such Securities and (B)
                  that the Company will provide (and the Company shall promptly
                  so provide) to such Person, or any beneficial owner of such
                  Securities holding through such Person (upon written request
                  to the Company sent to an address specified in such notice),
                  such other information as such Person or beneficial owner, as
                  the case may be, reasonably may request in order to enable it
                  to determine the federal income tax consequences to it
                  resulting from the satisfaction and discharge of the Company's
                  indebtedness in respect of such Securities. Thereafter, the
                  Company shall, within forty-five (45) days after the end of
                  each calendar year, give to each Person who at any time during
                  such calendar year was a Holder of such Securities a notice
                  containing (X) such information as may be necessary to enable
                  such Person to report its income, gain or loss for federal
                  income tax purposes with respect to such Securities or the
                  assets held on deposit in respect thereof during such calendar
                  year or the portion thereof during which such

                                        5

<PAGE>

                  Person was a Holder of such Securities, as the case may be
                  (such information to be set forth for such calendar year as a
                  whole and for each month during such year) and (Y) a statement
                  to the effect that the Company will provide (and the Company
                  shall promptly so provide) to such Person, or any beneficial
                  owner of such Securities holding through such Person (upon
                  written request to the Company sent to an address specified in
                  such notice), such other information as such Person or
                  beneficial owner, as the case may be, reasonably may request
                  in order to enable it to determine its income, gain or loss
                  for federal income tax purposes with respect to such
                  Securities or such assets for such year or portion thereof, as
                  the case may be. The obligation of the Company to provide or
                  cause to be provided information for purposes of income tax
                  reporting by any Person as described in the first two
                  sentences of this paragraph shall be deemed to have been
                  satisfied to the extent that the Company has provided or
                  caused to be provided substantially comparable information
                  pursuant to any requirements of the Internal Revenue Code of
                  1986, as amended from time to time (the "Code") and United
                  States Treasury regulations thereunder.

                  (ii)     Notwithstanding the provisions of subparagraph (i)
                  above, the Company shall not be required to give any notice
                  specified in such subparagraph or to otherwise furnish any of
                  the information contemplated therein if the Company shall have
                  delivered to the Trustee an Opinion of Counsel to the effect
                  that the Holders of such Securities will not recognize income,
                  gain or loss for federal income tax purposes as a result of
                  the satisfaction and discharge of the Company's indebtedness
                  in respect of such Securities and such Holders will be subject
                  to federal income taxation on the same amounts and in the same
                  manner and at the same times as if such satisfaction and
                  discharge had not occurred.

                  (iii)    Anything in this clause (u) to the contrary
                  notwithstanding, the Company shall not be required to give any
                  notice specified in subparagraph (i) or to otherwise furnish
                  the information contemplated therein or to deliver any Opinion
                  of Counsel contemplated by subparagraph (ii) if the Company
                  shall have caused Securities of Series No. 13 to be deemed to
                  have been paid for purposes of the Indenture, as provided in
                  Section 901 of the Original Indenture, but shall not have
                  effected the satisfaction and discharge of its indebtedness in
                  respect of such Securities pursuant to such Section.

         (v)      If the Company terminates or reduces the aggregate principal
         amount of unutilized commitments of the Banks to provide Credit
         Extensions under the Credit Agreement pursuant to Section 2.10 thereof,
         such termination or reduction shall, to the extent thereof, be deemed
         to satisfy and discharge the obligation of the Company, if any, to pay
         the principal amount of the Securities of Series No. 13. Upon payment
         of the Company's Principal Obligations under the Credit Agreement and
         the termination of the commitments of the Banks to provide Credit
         Extensions under the Credit Agreement, the obligation of the Company,
         if any, to pay the principal amount of the Securities of Series No. 13
         shall be deemed satisfied and discharged.

                  On the date which is thirty (30) days after the maturity of
         the Securities of Series No. 13, the Trustee may conclusively presume
         that the obligation of the Company to pay principal on the Securities
         of Series No. 13 as the same shall have become due and payable shall
         have been fully satisfied and discharged unless and until the Trustee
         shall have received a written notice prior to such date from the Holder
         thereof stating that the

                                        6

<PAGE>

         principal of Securities of Series No. 13 has become due and payable and
         specifying the amount of funds required to make such payment.

                  Notwithstanding anything to the contrary contained herein, the
         aggregate amount of principal actually due on the Securities of Series
         No. 13 shall not exceed the aggregate amount of the Principal
         Obligations of the Company (in respect of advances and letters of
         credit) under the Credit Agreement.

         (w)      The Securities of Series No. 13 are subject to the following
         voting restrictions: The Administrative Agent may attend such meeting
         or meetings of Holders of Securities of one or more, or all, series or
         any Tranche or Tranches thereof, under the Indenture, or at its option,
         deliver its proxy in connection therewith, as related to matters with
         respect to which it is entitled to vote or consent. So long as no
         "Event of Default" under the Indenture or any "Event of Default" under
         the Credit Agreement shall have occurred and be continuing, either at
         any such meeting or meetings, or otherwise when the consent of Holders
         of Securities of any series or Tranche is sought without a meeting, the
         Administrative Agent shall vote, or shall consent with respect thereto,
         proportionately with the vote or consent of the Holders of all other
         Securities of any series or Tranche Outstanding under the Indenture who
         are eligible to vote or consent, as indicated in a Bondholder's
         Certificate delivered to the Administrative Agent. If any "Event of
         Default" exists under the Indenture or the Credit Agreement, the
         Administrative Agent (i) may vote or consent the "Outstandings" (as
         defined in the Credit Agreement) as it elects and (ii) shall vote or
         consent the excess of the aggregate "Commitment Amounts" (as defined in
         the Credit Agreement) over the "Outstandings" (as defined in the Credit
         Agreement) proportionately with the vote or consent of the Holders of
         all other Securities of any series or Tranche Outstanding under the
         Indenture who are eligible to vote or consent, as indicated in a
         Bondholder's Certificate delivered to such Holders. Notwithstanding the
         foregoing, the provisions of this paragraph relating to voting or
         consent shall not apply, and the Administrative Agent may vote or
         consent without restriction in accordance with the terms of the
         Indenture, if the matter with respect to which the vote or consent is
         taken is a matter which, under the terms of Section 1402 of the
         Original Indenture, requires the approval or consent of the Holders of
         all Securities then Outstanding and directly affected by such matter.

         (x)      The Securities of Series No. 13 shall be substantially in the
         form attached hereto as Exhibit A and shall have such further terms as
         are set forth in such form.

                                  ARTICLE TWO

                            MISCELLANEOUS PROVISIONS

         (a)      This Supplemental Indenture No. 14 is a supplement to the
         Original Indenture. As previously supplemented and further supplemented
         by this Supplemental Indenture No. 14, the Original Indenture is in all
         respects ratified, approved and confirmed, and the Original Indenture,
         all previous supplements thereto and this Supplemental Indenture No. 14
         shall together constitute one and the same instrument.

         (b)      This Securities of Series No. 13 have been issued by the
         Company to the Administrative Agent to (i) secure the payment of the
         Company's Principal Obligations under the Credit Agreement and (ii)
         provide to such persons the benefits of the security provided for in
         this Security pursuant to the Indenture.

                                        7

<PAGE>

                  IN WITNESS WHEREOF, the parties hereto have caused this
Supplemental Indenture No. 14 to be duly executed as of the day and year first
above written.

                                       PUBLIC SERVICE COMPANY OF COLORADO

                                       By:  /S/ BENJAMIN G.S. FOWKE III
                                           -------------------------------------

                                           Name:  Benjamin G. S. Fowke III
                                           Title: Vice President and Treasurer

STATE OF MINNESOTA         )
                           ) ss.:
CITY OF MINNEAPOLIS        )

         On the 8th day of May, 2003, before me personally came Benjamin G. S.
Fowke III to me known, who, being by me duly sworn, did depose and say that he
is a Vice President and Treasurer of Public Service Company of Colorado, one of
the corporations described in and which executed the foregoing instrument; and
that he signed his name thereto by authority of the Board of Directors of said
corporation.

                                       /S/ SHARON M. QUELLHORST
                                       ----------------------------------------
                                       Name: Sharon M. Quellhorst
            [notary seal]              Notary Public, State of Minnesota

                                           Commission Expires: January 31, 2005

                                        8

<PAGE>

                                       U.S. BANK TRUST NATIONAL ASSOCIATION,
                                                             Trustee

                                       By: /S/ IGNAZIO TAMBURELLO
                                           -------------------------------------

                                           Name:  Ignazio Tamburello
                                           Title: Assistant Vice President

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

         On the 8th day of May, 2003, before me personally came Ignazio
Tamburello, to me known, who, being by me duly sworn, did depose and say that he
is an Assistant Vice President of U.S. Bank Trust National Association, the
banking association described in and which executed the foregoing instrument;
and that he signed his name thereto by authority of the Board of Directors of
said banking association.

                                           /JANET O'HARA
                                       -----------------------------------------
                                       Name:  Janet O'Hara
           [notary seal]               Notary Public, State of New York

                                       Commission Expires: November 3, 2005

                                        9

<PAGE>

                                                                       EXHIBIT A

                                FORM OF SECURITY

                   (See legend at the end of this Security for
                  restrictions on transfer and change of form)

                       PUBLIC SERVICE COMPANY OF COLORADO

 First Collateral Trust Bond, Series No. 13 (Credit Agreement Collateral Bonds)

                       Issue Date:         [May __], 2003
                  Stated Maturity:          May 14, 2004

                    This Security is not a Discount Security
              within the meaning of the within-mentioned Indenture

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

Principal Amount                                         Registered No. 1

         PUBLIC SERVICE COMPANY OF COLORADO, a corporation duly organized and
existing under the laws of the State of Colorado (herein called the "Company,"
which term includes any successor corporation under the Indenture referred to
below), for value received, hereby promises to pay to [ ], as Administrative
Agent, or registered assigns, the principal sum of [ ] Dollars on the Stated
Maturity specified above. This Security shall not bear interest.

         Payment of the principal of this Security at Maturity shall be made
upon presentation of this Security at the Corporate Trust Office of U.S. Bank
Trust National Association, in New York, New York or at such other office or
agency as may be designated for such purpose by the Company from time to time.
Payment of the principal of this Security, as aforesaid, shall be made in such
coin or currency of the United States of America as at the time of payment shall
be legal tender for the payment of public and private debts.

         This Security is one of a duly authorized issue of securities of the
Company (herein called the "Securities"), issued and issuable in one or more
series under and equally secured by an Indenture, dated as of October 1, 1993
(such Indenture as originally executed and delivered and as supplemented or
amended from time to time thereafter, together with any constituent instruments
establishing the terms of particular Securities, being herein called the
"Indenture"), between the Company and U.S. Bank Trust National Association
(formerly First Trust of New York, National Association) as successor trustee
(herein called the "Trustee," which term includes any successor trustee under
the Indenture), to which

                                   EXHIBIT A-1

<PAGE>

Indenture and all indentures supplemental thereto reference is hereby made for a
description of the property mortgaged, pledged and held in trust, the nature and
extent of the security and the respective rights, limitations of rights, duties
and immunities of the Company, the Trustee and the Holders of the Securities
thereunder and of the terms and conditions upon which the Securities are, and
are to be, authenticated and delivered and secured. The acceptance of this
Security shall be deemed to constitute the consent and agreement by the Holder
hereof to all of the terms and provisions of the Indenture. This Security is one
of the series designated above.

         The Company has entered into a Credit Agreement (as it may be amended,
supplemented, restated or otherwise modified from time to time, the "Credit
Agreement"), dated as of May 16, 2003, with Bank One, NA, as Administrative
Agent (the "Administrative Agent") and the several financial institutions and
other persons from time to time party thereto (collectively, the "Banks"),
pursuant to which the Banks have agreed to make advances, to issue or
participate in letters of credit and to grant certain other financial
accommodations to the Company up to an aggregate principal amount of Three
Hundred Fifty Million dollars ($350,000,000) (the "Credit Extensions"). The
Credit Agreement requires the Company to cause the Company's obligations to pay
the principal amount due under the Credit Agreement with respect to the Credit
Extensions and to fund the Cash Collateral Account (as defined in the Credit
Agreement) pursuant to Section 2.7(g) and/or 7.2(c) thereof (collectively, the
"Principal Obligations"), to be ratably secured with all indebtedness of the
Company under the Indenture, as a condition to, and as consideration for, the
obligation of the Banks to make the Credit Extensions in accordance with the
terms of the Credit Agreement. This Security has been issued in order to satisfy
that requirement.

         If the Company terminates or reduces the aggregate principal amount of
unutilized commitments of the Banks to provide Credit Extensions under the
Credit Agreement pursuant to Section 2.10 thereof, such termination or reduction
shall, to the extent thereof, be deemed to satisfy and discharge the obligation
of the Company, if any, to pay the principal amount of the Securities of Series
No. 13. Upon payment of the Company's Principal Obligations under the Credit
Agreement and the termination of the commitments of the Banks to provide Credit
Extensions under the Credit Agreement, the obligation of the Company, if any, to
pay the principal amount of the Securities of Series No. 13 shall be deemed
satisfied and discharged.

         On the date which is thirty (30) days after the maturity of the
Securities of Series No. 13, the Trustee may conclusively presume that the
obligation of the Company to pay principal on the Securities of Series No. 13 as
the same shall have become due and payable shall have been fully satisfied and
discharged unless and until the Trustee shall have received a written notice
prior to such date from the Holder thereof stating that the principal of
Securities of Series No. 13 has become due and payable and specifying the amount
of funds required to make such payment.

         Notwithstanding anything to the contrary contained herein, the
aggregate amount of principal actually due on the Securities of Series No. 13
shall not exceed the aggregate amount of the Principal Obligations of the
Company (in respect of advances and letters of credit) under the Credit
Agreement.

         If the Stated Maturity shall not be a Business Day (as hereinafter
defined), payment of the amounts due on this Security on such date may be made
on the next succeeding Business Day.

         This Security is not subject to redemption at the option of the Company
prior to the Stated Maturity thereof, other than as set forth in the Indenture.

         Upon the occurrence of an Event of Default (as defined in the Credit
Agreement) pursuant to Section 7.1(a), (b) or (p) thereof or any other Event of
Default under the Credit Agreement that results in

                                   EXHIBIT A-2

<PAGE>

the acceleration of any Principal Obligations thereunder, then the Securities of
Series No. 13 shall be redeemable in whole or in part upon receipt by the
Trustee and the Company of a written demand (a "Redemption Demand") from the
Administrative Agent specifying a Demand Redemption Date (which may be the date
of receipt by the Company of the Redemption Demand) stating that there has been
such an Event of Default and demanding redemption of the Securities (a) to the
extent of the principal amount of the accelerated Principal Obligations, and/or
(b) in the case of an Event of Default arising under the Credit Agreement
pursuant to Section 7.1(p), to the extent of the amount then required to be
deposited pursuant to Section 2.7(g) and/or 7.2(c) of the Credit Agreement. The
Securities of Series No. 13 shall be redeemed by the Company on the Demand
Redemption Date at a redemption price equal to 100% of the principal amount
thereof to be redeemed; provided, however, to the extent the Company pays the
principal amount of the Principal Obligations so accelerated and/or the amounts
due pursuant to Section 2.7(g) and/or 7.2(c) of the Credit Agreement, the
Company's obligation to pay the redemption price of such Securities shall be
deemed satisfied. Promptly after receipt of the redemption price, the
Administrative Agent shall surrender the Securities of Series No. 13 to be
redeemed to the Trustee. Upon the surrender of any Security which is to be
redeemed only in part, the Company shall execute and the Trustee shall
authenticate a new Security or Securities in an aggregate principal amount equal
to and in exchange for the unredeemed portion of the principal of the Security
so surrendered. If a Redemption Demand is rescinded by the Administrative Agent
by written notice to the Trustee and the Company prior to the Demand Redemption
Date, the Redemption Demand shall be automatically annulled; but no such
rescission shall extend to or affect any subsequent Event of Default pursuant to
Section 7.1(a), (b) or (p) of the Credit Agreement or any other Event of Default
under the Credit Agreement resulting in the acceleration of Principal
Obligations under the Credit Agreement or impair any right consequent thereon.

         If an Event of Default (as defined in the Indenture) shall occur and be
continuing, the principal of this Security may be declared due and payable in
the manner and with the effect provided in the Indenture.

         The Administrative Agent may attend such meeting or meetings of Holders
of Securities of one or more, or all, series or any Tranche or Tranches thereof,
under the Indenture, or at its option, deliver its proxy in connection
therewith, as related to matters with respect to which it is entitled to vote or
consent. So long as no "Event of Default" under the Indenture or any "Event of
Default" under the Credit Agreement shall have occurred and be continuing,
either at any such meeting or meetings, or otherwise when the consent of Holders
of Securities of any series or Tranche is sought without a meeting, the
Administrative Agent shall vote, or shall consent with respect thereto,
proportionately with the vote or consent of the Holders of all other Securities
of any series or Tranche Outstanding under the Indenture who are eligible to
vote or consent, as indicated in a Bondholder's Certificate delivered to such
Holder. If any "Event of Default" exists under the Indenture or the Credit
Agreement, the Administrative Agent (i) may vote or consent the Outstandings (as
defined in the Credit Agreement) as it elects and (ii) shall vote or consent the
excess of the aggregate "Commitment Amounts" (as defined in the Credit
Agreement) over the "Outstandings" (as defined in the Credit Agreement)
proportionately with the vote or consent of the Holders of all other Securities
of any series or Tranche Outstanding under the Indenture who are eligible to
vote or consent, as indicated in a Bondholder's Certificate delivered to the
Administrative Agent. Notwithstanding the foregoing, the provisions of this
paragraph relating to voting or consent shall not apply, and the Administrative
Agent may vote or consent without restriction in accordance with the terms of
the Indenture, if the matter with respect to which the vote or consent is taken
is a matter which, under the terms of Section 1402 of the Original Indenture,
requires the approval or consent of the Holders of all Securities then
Outstanding and directly affected by such matter.

         The Indenture permits, with certain exceptions as therein provided, the
Trustee to enter into one or more supplemental indentures for the purpose of
adding any provisions to, or changing in any manner or eliminating any of the
provisions of, the Indenture with the consent of the Holders of not less than a

                                   EXHIBIT A-3

<PAGE>

majority in aggregate principal amount of the Securities of all series then
Outstanding under the Indenture, considered as one class; provided, however,
that if there shall be Securities of more than one series Outstanding under the
Indenture and if a proposed supplemental indenture shall directly affect the
rights of the Holders of Securities of one or more, but less than all, of such
series, then the consent only of the Holders of a majority in aggregate
principal amount of the Outstanding Securities of all series so directly
affected, considered as one class, shall be required; and provided, further,
that if the Securities of any series shall have been issued in more than one
Tranche and if the proposed supplemental indenture shall directly affect the
rights of the Holders of Securities of one or more, but less than all, of such
Tranches, then the consent only of the Holders of a majority in aggregate
principal amount of the Outstanding Securities of all Tranches so directly
affected, considered as one class, shall be required; and provided, further,
that the Indenture permits the Trustee to enter into one or more supplemental
indentures for limited purposes without the consent of any Holders of
Securities. The Indenture also contains provisions permitting the Holders of a
majority in principal amount of the Securities then Outstanding, on behalf of
the Holders of all Securities, to waive compliance by the Company with certain
provisions of the Indenture and certain past defaults under the Indenture and
their consequences. Any such consent or waiver by the Holder of this Security
shall be conclusive and binding upon such Holder and upon all future Holders of
this Security and of any Security issued upon the registration of transfer
hereof or in exchange therefor or in lieu hereof, whether or not notation of
such consent or waiver is made upon this Security.

         As provided in the Indenture and subject to certain limitations therein
set forth, this Security or any portion of the principal amount hereof will be
deemed to have been paid for all purposes of the Indenture and to be no longer
Outstanding thereunder, and, at the election of the Company, the Company's
entire indebtedness in respect thereof will be satisfied and discharged, if
there has been irrevocably deposited with the Trustee or any Paying Agent (other
than the Company), in trust, money in an amount which will be sufficient and/or
Eligible Obligations, the principal of and interest on which when due, without
regard to any reinvestment thereof, will provide moneys which, together with
moneys so deposited, will be sufficient, to pay when due the principal of and
interest on this Security or portion hereof when due.

         This Security is not transferable except to a successor to the
Administrative Agent under the Credit Agreement upon delivery to the Trustee of
a Company Request requesting such transfer; provided, however, that, if an Event
of Default exists under the Credit Agreement, the Administrative Agent may
submit a written notice of its successor directly to the Trustee. Before any
transfer of this Security will be recognized or given effect by the Company or
the Trustee, the Holder shall note the amounts of all principal prepayments
hereon, and shall notify the Company and the Trustee of the name and address of
the transferee and shall afford the Company and the Trustee the opportunity of
verifying the notation as to prepayment of principal. By the acceptance hereof
the Holder of this Security and each transferee shall be deemed to have agreed
to indemnify and hold harmless the Company and the Trustee against all losses,
claims, damages or liability arising out of any failure on the part of the
Holder or of any such transferee to comply with the requirements of the
preceding sentence. Any such transfer is registrable in the Security Register,
upon surrender of this Security for registration of transfer at the office of
U.S. Bank Trust National Association, in New York, New York or such other office
or agency as may be designated by the Company from time to time, duly endorsed
by, or accompanied by a written instrument of transfer in form satisfactory to
the Company and the Security Registrar duly executed by, the Holder hereof or
his attorney duly authorized in writing, and thereupon one or more new
Securities of this series of authorized denominations and of like tenor and
aggregate principal amount, will be issued to the designated transferee or
transferees.

                                   EXHIBIT A-4

<PAGE>

         This Bond has not been registered under the Securities Act of 1933, as
amended, and may not be offered or sold in contravention of said Act and is not
transferable except to a successor to the Administrative Agent under the Credit
Agreement.

         No service charge shall be made for any such registration of transfer.

         Prior to due presentment of this Security 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 Security is registered as the absolute owner
hereof for all purposes, whether or not this Security be overdue, and neither
the Company, the Trustee nor any such agent shall be affected by notice to the
contrary.

         The Indenture and the Securities shall be governed by and construed in
accordance with the laws of the State of New York.

         As used herein "Business Day" means any day, other than a Saturday or
Sunday, which is not a day on which banking institutions or trust companies in
The City of New York, New York or other city in which is located any office or
agency maintained for the payment of principal or interest on this Security, are
authorized or required by law, regulation or executive order to remain closed.
All other terms used in this Security which are defined in the Indenture shall
have the meanings assigned to them in the Indenture.

         As provided in the Indenture, no recourse shall be had for the payment
of the principal of or interest on any Securities, 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 the
Indenture, against, and no personal liability whatsoever shall attach to, or be
incurred by, any incorporator, shareholder, 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 the Indenture and all the Securities
are solely corporate obligations 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 the Indenture and the issuance of the
Securities.

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

                                   EXHIBIT A-5

<PAGE>

         IN WITNESS WHEREOF, the Company has caused this instrument to be duly
executed and its corporate seal to be hereunto affixed and attested.

                                           PUBLIC SERVICE COMPANY OF COLORADO

                                           By:__________________________________
                                                 Vice President and Treasurer

Attest: ___________________________
           Assistant Secretary

                          CERTIFICATE OF AUTHENTICATION

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

Dated:_____________________________

        U.S. BANK TRUST              OR              U.S. BANK TRUST
     NATIONAL ASSOCIATION,                         NATIONAL ASSOCIATION,
          as Trustee                                    as Trustee

By:________________________________        By:__________________________________
         Authorized Officer                    AS AUTHENTICATING AGENT

                                           By:__________________________________
                                                    Authorized Officer

         THE HOLDER OF THIS BOND BY ITS ACCEPTANCE HEREOF AGREES TO RESTRICTIONS
ON TRANSFER, RESTRICTIONS ON VOTING, TO WAIVERS OF CERTAIN RIGHTS OF EXCHANGE,
AND TO INDEMNIFICATION PROVISIONS AS SET FORTH BELOW. IN ADDITION, THE BOND
REPRESENTED BY THIS CERTIFICATE HAS NOT BEEN REGISTERED UNDER THE SECURITIES ACT
OF 1933 AND SUCH BOND MAY NOT BE TRANSFERRED WITHOUT COMPLIANCE WITH APPLICABLE
SECURITIES LAWS.

         THIS SECURITY MAY NOT BE TRANSFERRED OR EXCHANGED, NOR MAY ANY
PURPORTED TRANSFER BE REGISTERED, EXCEPT TO A SUCCESSOR TO THE ADMINISTRATIVE
AGENT UNDER THE CREDIT AGREEMENT REFERRED TO HEREIN.

         THIS SECURITY IS SUBJECT TO CERTAIN VOTING RESTRICTIONS SET FORTH
HEREIN.

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

                                   EXHIBIT A-6

<PAGE>

  FOR VALUE RECEIVED the undersigned hereby sells, assigns and transfers unto

________________________________________________________________________________

     [please insert social security or other identifying number of assignee]

________________________________________________________________________________
            [please print or typewrite name and address of assignee]

________________________________________________________________________________

the within Security of PUBLIC SERVICE COMPANY OF COLORADO and does hereby
irrevocably constitute and appoint __________________________________ ,
Attorney, to transfer said Security on the books of the within-mentioned
Company, with full power of substitution in the premises.

Dated:_____________________________

                 _______________________________________________

         Notice: The signature to this assignment must correspond with the name
         as written upon the face of the Security in every particular without
         alteration or enlargement or any change whatsoever.

                                   EXHIBIT A-7

<PAGE>

                                                                      SCHEDULE A

                             SUPPLEMENTAL INDENTURES

<TABLE>
<CAPTION>
     DATE OF                                                           PRINCIPAL
   SUPPLEMENTAL                                      PRINCIPAL          AMOUNT
    INDENTURE             SERIES OF BONDS          AMOUNT ISSUED      OUTSTANDING
    ---------             ---------------          -------------      -----------
<S>                    <C>                         <C>                <C>
November 1, 1993            Series No. 1           $134,500,000       $134,500,000
January 1, 1994        Series No. 2 due 2001       $102,667,000           None
                               and
                       Series No. 2 due 2024       $110,000,000       $110,000,000
September 2, 1994               None                   None               None
(Appointment of
Successor Trustee)
May 1, 1996                 Series No. 3           $125,000,000       $125,000,000
November 1, 1996            Series No. 4           $250,000,000       $175,000,000
February 1, 1997            Series No. 5           $150,000,000           None
April 1, 1998               Series No. 6           $250,000,000           None
August 15, 2002             Series No. 7           $48,750,000        $48,750,000
September 1, 2002           Series No. 8           $600,000,000           None
September 15, 2002          Series No. 9           $530,000,000       $530,000,000
April 1, 2003               Series No. 10          $600,000,000       $600,000,000
March 1, 2003               Series No. 11          $250,000,000       $250,000,000
</TABLE>

                                  SCHEDULE A-1

Source: [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00052-of-00352.parquet"}, [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00052-of-00352.parquet"}]]