<PAGE>

                                                                Exhibit 4(a)(14)

================================================================================


                              UTILICORP UNITED INC.


                                       and

                           BANK ONE TRUST COMPANY, NA
                  (formerly The First National Bank of Chicago)
                                   as Trustee

                              _____________________


                           7 5/8% Senior Notes due 2009


                              _____________________


                        THIRTEENTH SUPPLEMENTAL INDENTURE

                          Dated as of November 16, 1999


                              _____________________


================================================================================


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                                TABLE OF CONTENTS

<TABLE>
<CAPTION>

                                                                                                PAGE
<S>                                                                                                <C>
ARTICLE ONE DEFINITIONS............................................................................2

ARTICLE TWO TERMS AND ISSUANCE OF THE SENIOR NOTES.................................................3

         Section 201.  Issue of Senior Notes.......................................................3
         Section 202.  Form of Senior Notes; Incorporation of Terms................................3
         Section 203.  Place of Payment............................................................3
         Section 204.  Limitation on Issuance of Mortgage Bonds....................................3

ARTICLE THREE MISCELLANEOUS........................................................................4

         Section 301.  Execution of Supplemental Indenture.........................................4
         Section 302.  Conflict With Trust Indenture Act...........................................4
         Section 303.  Effect of Headings..........................................................4
         Section 304.  Successors and Assigns......................................................4
         Section 305.  Separability Clause.........................................................4
         Section 306.  Benefits of Thirteenth Supplemental Indenture...............................4
         Section 307.  Governing Law...............................................................5
         Section 308.  Execution and Counterparts..................................................5

</TABLE>


<PAGE>

                  THIRTEENTH SUPPLEMENTAL INDENTURE, dated as of November
16,1999 (herein called the "Thirteenth Supplemental Indenture"), between
UTILICORP UNITED INC., a corporation duly organized and existing under the laws
of the State of Delaware (hereinafter called the "Company"), party of the first
part, and BANK ONE TRUST COMPANY, NA (formerly The First National Bank of
Chicago), a national banking association duly organized and existing under the
laws of the United States, as Trustee under the Original Indenture referred to
below (hereinafter called the "Trustee"), party of the second part.

                                   WITNESSETH:

                  WHEREAS, the Company has heretofore executed and delivered to
the Trustee an Indenture, dated as of November 1, 1990 (hereinafter called the
"Original Indenture"), to provide for the issuance from time to time of certain
of its unsecured senior notes (hereinafter called the "Securities"), the form
and terms of which are to be established as set forth in Sections 201 and 301 of
the Original Indenture; and

                  WHEREAS, Section 901 of the Original Indenture provides, among
other things, that the Company and the Trustee may enter into indentures
supplemental to the Original Indenture for, among other things, the purpose of
establishing the form or terms of the Securities of any series as permitted in
Sections 201 and 301 of the Original Indenture; and

                  WHEREAS, the Company desires to create a series of the
Securities in an aggregate principal amount of $200,000,000 to be designated
the "7 5/8% Senior Notes due 2009" (the "Senior Notes"), and all action on
the part of the Company necessary to authorize the issuance of the Senior
Notes under the Original Indenture and this Thirteenth Supplemental Indenture
has been duly taken; and

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                                      -2-


                  WHEREAS, all acts and things necessary to make the Senior
Notes when executed by the Company and completed, authenticated and delivered by
the Trustee as in the Original Indenture and this Thirteenth Supplemental
Indenture provided, the valid and binding obligations of the Company and to
constitute these presents a valid and binding supplemental indenture and
agreement according to its terms, have been done and performed; and

                  WHEREAS, Section 901 of the Original Indenture provides, among
other things, that the Company and the Trustee may enter into indentures
supplemental to the Original Indenture to, among other things, add to the
covenants of the Company for the benefit of the Holders of all or any series of
Securities; and

                  WHEREAS, the Company desires to limit the issuance of Mortgage
Bonds under its General Mortgage (as hereinafter defined) as set forth in
Section 204 of this Thirteenth Supplemental Indenture for the benefit of the
Holders of the Senior Notes;

                  NOW, THEREFORE, THIS THIRTEENTH SUPPLEMENTAL INDENTURE
WITNESSETH:

                  That in consideration of the premises, the Company covenants
and agrees with the Trustee, for the equal benefit of holders of the Senior
Notes, as follows:

                                   ARTICLE ONE

                                   DEFINITIONS

                  The use of the terms and expressions herein is in accordance
with the definitions, uses and constructions contained in the Original Indenture
and the form of Senior Note attached hereto as Exhibit A.


<PAGE>
                                      -3-


                                   ARTICLE TWO

                     TERMS AND ISSUANCE OF THE SENIOR NOTES

                  Section 201. ISSUE OF SENIOR NOTES. A series of Securities
which shall be designated the "7 5/8% Senior Notes due 2009" shall be
executed, authenticated and delivered in accordance with the provisions of,
and shall in all respects be subject to, the terms, conditions and covenants
of the Original Indenture and this Thirteenth Supplemental Indenture
(including the form of Senior Note set forth as Exhibit A hereto). The
aggregate principal amount of Senior Notes of the series created hereby which
may be authenticated and delivered under the Original Indenture shall not,
except as permitted by the provisions of the Original Indenture, exceed
$200,000,000.

                  Section 202. FORM OF SENIOR NOTES; INCORPORATION OF TERMS. The
form of the Senior Notes shall be substantially in the form of Exhibit A
attached hereto. The terms of such Senior Notes are herein incorporated by
reference and are part of this Thirteenth Supplemental Indenture.

                  Section 203. PLACE OF PAYMENT. The Place of Payment will be
initially the corporate trust offices of the Trustee which, at the date hereof,
are located at Bank One Trust Company, NA, One Bank One Plaza, Suite 0126,
Chicago, Illinois 60670-0126.

                  Section 204. LIMITATION ON ISSUANCE OF MORTGAGE BONDS. The
Company will not issue any Mortgage Bonds under its General Mortgage Indenture
and Deed of Trust, dated September 15, 1988, between the Company and Commerce
Bank of Kansas City, N.A., as Trustee (the "General Mortgage"), without making
effective provision, and the Company covenants that in any such case effective
provisions will be made, whereby the Senior Notes


<PAGE>
                                      -4-


shall be directly secured by the General Mortgage equally and ratably with any
and all other obligations and indebtedness thereby secured.

                                  ARTICLE THREE

                                  MISCELLANEOUS

                  Section 301. EXECUTION OF SUPPLEMENTAL INDENTURE. This
Thirteenth Supplemental Indenture is executed and shall be construed as an
indenture supplemental to the Original Indenture and, as provided in the
Original Indenture, this Thirteenth Supplemental Indenture forms a part thereof.

                  Section 302. CONFLICT WITH TRUST INDENTURE ACT. If any
provision hereof limits, qualifies or conflicts with another provision hereof
which is required to be included in this Thirteenth Supplemental Indenture by
any of the provisions of the Trust Indenture Act, such required provision shall
control.

                  Section 303.  EFFECT OF HEADINGS.The Article and Section
headings herein are for convenience only and shall not affect the construction
hereof.

                  Section 304. SUCCESSORS AND ASSIGNS. All covenants and
agreements in this Thirteenth Supplemental Indenture by the Company shall
bind its successors and assigns, whether so expressed or not.

                  Section 305. SEPARABILITY CLAUSE. In case any provision in
this Thirteenth Supplemental Indenture or in the Senior Notes shall be invalid,
illegal or unenforceable, the validity, legality and enforceability of the
remaining provisions shall not in any way be affected or impaired thereby.


<PAGE>
                                      -5-


                  Section 306. BENEFITS OF THIRTEENTH SUPPLEMENTAL INDENTURE.
Nothing in this Thirteenth Supplemental Indenture or in the Senior Notes,
express or implied, shall give to any person, other than the parties hereto and
their successors hereunder and the holders, any benefit or any legal or
equitable right, remedy or claim under this Thirteenth Supplemental Indenture.

                  Section 307. GOVERNING LAW. This Thirteenth Supplemental
Indenture and each Senior Note shall be deemed to be a contract made under the
laws of the State of New York, and for all purposes shall be governed by and
construed in accordance with the laws of said State.

                  Section 308. EXECUTION AND COUNTERPARTS. This Thirteenth
Supplemental Indenture may be executed in any number of counterparts, each of
which shall be deemed to be an original, but all such counterparts shall
together constitute but one and the same instrument.


<PAGE>
                                      -6-


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

                                           UTILICORP UNITED INC.

[Seal]                                     By: /s/ Dale J. Wolf
                                              --------------------------------
                                              Name:  Dale J. Wolf
                                              Title: Vice President, Finance,
                                                     Treasurer and Secretary

Attest:
/s/ Douglas P. Evanson
------------------------------
       Title:  Asst. Treasurer

                                           BANK ONE TRUST COMPANY, NA
                                            as Trustee

[Seal]                                     By: /s/ Leland Hansen
                                              -------------------------------
                                              Name: Leland Hansen
                                              Title: Asst Vice Pres.

Attest:

/s/ Joan E. Blume
------------------------------
 Title:  Trust Officer


<PAGE>

STATE OF  Missouri)
          --------
                  )  ss.:
COUNTY OF  Jackson)
          --------

                  On the 12th day of November, 1999, before me personally
                         ----        --------     -
came Dale J. Wolf, to me known, who, being by me duly sworn, did depose and say
     ------------
that he is Vice President, Treasurer and Secretary of UtiliCorp United Inc.,
           ---------------------------------------
the corporation described in and which executed the foregoing instrument;
that he knows the seal of said corporation; that the seal affixed to said
instrument is such corporate seal; that it was so affixed by authority of the
Board of Directors of said corporation, and that he signed his name thereto
by like authority.

                                                   /s/ Lewisann Rosenberger
                                                   ------------------------
                                                   Notary Public,
                                                   State of Missouri----------

                                                   [Notary Seal]


STATE OF Illinois)
         --------
                 )  ss.:
COUNTY OF    Cook)
          -------

                  On the 16 day of Nov., 1999, before me personally
                         --        ----     -
came Leland Hansen, to me known, who, being by me duly sworn, did depose and say
     -------------
that he is Joan Blume of Bank One Trust Company, NA, the national
           ----------
banking association described in and which executed the foregoing instrument;
that he knows the seal of said association; that the seal affixed to said
instrument is such association seal; that it was so affixed by authority of the
Board of Directors of said association, and that he signed his name thereto by
like authority.

                                                   /s/ Nilda Sierra
                                                   ------------------
                                                   Notary Public,
                                                   State of _________

                                                   [Notary Seal]

<PAGE>
                                                                   EXHIBIT A

                          [FORM OF FACE OF SENIOR NOTE]

THIS SECURITY IS A GLOBAL SECURITY WITHIN THE MEANING OF THE INDENTURE
HEREINAFTER REFERRED TO AND IS REGISTERED IN THE NAME OF A DEPOSITARY OR A
NOMINEE OF A DEPOSITARY. THIS GLOBAL SECURITY IS EXCHANGEABLE FOR SECURITIES
REGISTERED IN THE NAME OF A PERSON OTHER THAN THE DEPOSITARY OR ITS NOMINEE ONLY
IN THE LIMITED CIRCUMSTANCES HEREINAFTER DESCRIBED AND MAY NOT BE TRANSFERRED
EXCEPT AS A WHOLE BY THE DEPOSITARY TO A NOMINEE OF THE DEPOSITARY OR BY A
NOMINEE OF THE DEPOSITARY TO THE DEPOSITARY OR ANOTHER NOMINEE OF THE DEPOSITARY
OR BY THE DEPOSITARY OR ANY NOMINEE TO A SUCCESSOR OF THE DEPOSITARY OR A
NOMINEE OF SUCH SUCCESSOR.

REGISTERED                                                            REGISTERED

                              UTILICORP UNITED INC.

                           7 5/8% SENIOR NOTES DUE 2009

No. 918005 AW9                                       $

                  UTILICORP UNITED INC., a corporation duly organized and
existing under the laws of Delaware (herein called the "Company", which term
includes any successor corporation under the Indenture hereinafter referred to),
for value received, hereby promises to pay to
__________________________________, or registered assigns, the principal sum of
_________________________________________ DOLLARS on November 15, 2009, and to
pay interest thereon from November 16, 1999, or from the most recent Interest
Payment Date to which interest has been paid or duly provided for, semi-annually
on May 15 and November 15 in each year, commencing May 15, 2000, at the rate per
annum provided in the title hereof, until the principal hereof is paid or made
available for payment, and, subject to the terms of the Indenture, at the rate
per annum provided in the title hereof on any overdue principal and premium, if
any, and (to the extent that the payment of such interest shall be legally
enforceable) on any overdue installment of interest. The interest so payable,
and punctually paid or duly provided for, on any Interest Payment Date will, as
provided in such Indenture, be paid to the Holder in whose name this Security
(or one or more Predecessor Securities) is registered at the close of business
on the Regular Record Date for such interest payment, which shall be the May 1
or November 1 (whether or not a Business Day), as the case may be, next
preceding such Interest Payment Date. Any such interest not so punctually paid
or duly provided for will forthwith cease to be payable to the Holder on such
Regular Record Date, and may either be paid to the Holder in whose name this
Security (or one or more Predecessor Securities) is registered at the close of
business on a Special Record Date for the payment of such Defaulted Interest to
be fixed by the Trustee, in


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                                      -2-


which event notice whereof shall be given to Holders of Securities of this
series not less than 10 days prior to such Special Record Date, or may be paid
at any time in any other lawful manner not inconsistent with the requirements of
any securities exchange on which the Securities of this series may be listed,
and upon such notice as may be required by such exchange, all as more fully
provided in said Indenture.

                  Payment of the principal of and premium, if any, and interest
on this Security will be made at the office or agency of the Trustee maintained
for that purpose in the Borough of Manhattan, The City of New York, in such coin
or currency of the United States of America as at the time of payment is legal
tender for payment of public and private debts. The Company may pay principal by
check payable in such money or by wire transfer to a dollar account maintained
by the holder (if the holder of the Security holds an aggregate principal amount
of Securities in excess of $5,000,000). The Company may pay interest by mailing
a dollar check to a holder's registered address or, upon application by the
holder hereof to the Security Registrar, not later than the applicable record
date, by wire transfer to a dollar account maintained by the holder (if the
holder of the Security holds an aggregate principal amount of Securities in
excess of $5,000,000).

                  Reference is hereby made to the further provisions of this
Security set forth on the reverse hereof, which further provisions shall for all
purposes have the same effect as if set forth at this place.

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


<PAGE>
                                      -3-


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

                                           UTILICORP UNITED INC.

Dated:                                     By:__________________________________
                                                    Title:

                                           Attest:

                                           _____________________________________
[Seal]                                              Title:

TRUSTEE'S CERTIFICATE OF
   AUTHENTICATION

This is one of the Senior
Notes of the series designated
herein referred to in the
within-mentioned Indenture

BANK ONE TRUST COMPANY, NA
   as Trustee

By:________________________________
         Authorized Officer


<PAGE>

                        [FORM OF REVERSE OF SENIOR NOTE]

                              UTILICORP UNITED INC.

                           7 5/8% SENIOR NOTE DUE 2009

                  This Senior Note is one of a duly authorized series of
securities of the Company (herein called the "Securities"), issued and to be
issued in one or more series under an Indenture, dated as of November 1, 1990,
as amended and supplemented by the Thirteenth Supplemental Indenture dated as of
November 16, 1999 (as amended and supplemented, the "Indenture"), between the
Company and Bank One Trust Company, NA (formerly The First National Bank of
Chicago), as Trustee (herein called the "Trustee", which term includes any
successor trustee under the Indenture), to which Indenture and all indentures
supplemental thereto reference is hereby made for a statement of the respective
rights, limitations of rights, duties and immunities thereunder of the Company,
the Trustee and the Holders of the Securities and the terms upon which the
Securities are, and are to be, authenticated and delivered. This Security is one
of the series designated on the face hereof, limited in aggregate principal
amount to $200,000,000.

                  This Security is not subject to any sinking fund, nor may this
Security be redeemed at the option of the Company prior to the Maturity Date.

                  Interest payments for this Security will be computed and paid
on the basis of a 360-day year of twelve 30-day months. If an Interest Payment
Date falls on a day that is not a Business Day, such Interest Payment Date will
be the following day that is a Business Day.

                  The Indenture contains provisions for defeasance of (a) the
entire indebtedness of this Security and (b) certain restrictive covenants upon
compliance by the Company with certain conditions set forth therein.

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

                  The Indenture permits, with certain exceptions as therein
provided, the amendment thereof and the modification of the rights and
obligations of the Company and the rights of the Holders of the Securities of
each series to be affected under the Indenture at any time by the Company and
the Trustee with the consent of the Holders of not less than 66 2/3% in
principal amount of the Securities at the time Outstanding of all series to be
affected (voting as a class). The Indenture also contains provisions permitting
the Holders of specified percentages in principal amount of the Securities of
each series at the time Outstanding, on behalf of the Holders of all Securities
of such series, to waive compliance by the Company with certain provisions of
the Indenture and certain past defaults under the Indenture and their
consequences.


<PAGE>
                                      -2-


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
hereof or in lieu hereof, whether or not notation of such consent or waiver is
made upon this Security.

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

                  This Security shall be exchangeable for Securities registered
in the names of Persons other than the Depositary with respect to such series or
its nominee only as provided in this paragraph. This Security shall be so
exchangeable if (x) the Depositary notifies the Company that it is unwilling or
unable to continue as Depositary for such series or at any time ceases to be a
clearing agency registered as such under the Securities Exchange Act of 1934,
(y) the Company executes and delivers to the Trustee an Officers' Certificate
providing that this Security shall be so exchangeable or (z) there shall have
occurred and be continuing an Event of Default with respect to the Securities of
such series. Securities so issued in exchange for this Security shall be of the
same series, having the same interest rate, if any, and maturity and having the
same terms as this Security, in authorized denominations and in the aggregate
having the same principal amount as this Security and registered in such names
as the Depositary for such Global Security shall direct.

                  As provided in the Indenture and subject to certain
limitations therein set forth, the transfer of a Security of the series of which
this Security is a part is registrable in the Security Register, upon surrender
of this Security for registration of transfer at the office or agency of the
Company in any place where the principal of and premium, if any, and interest,
if any, on this Security are payable, 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 for the same aggregate principal amount, will be
issued to the designated transferee or transferees.

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

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


<PAGE>
                                      -3-


                  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 Holder in whose name this Security is registered as the 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.

                  This Security shall be governed by and construed in accordance
with the laws of the State of New York.

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