Exhibit 4(a)(6)

     Supplemental Indenture, dated as of September 1, 1995 (the
"Supplemental Indenture"), made by and between Northwestern Public Service
Company, a corporation organized and existing under the laws of the State
of Delaware (the "Company"), the post office address of which is 33 Third
Street, S.E., Huron, South Dakota 57350, and The Chase Manhattan Bank
(National Association), a national banking association organized and
existing under the laws of the United States of America (the "Trustee"), as
Trustee under the General Mortgage Indenture and Deed of Trust dated as of
August 1, 1993, hereinafter mentioned, the post office address of which is
4 Chase MetroTech Center, 3rd Floor, Brooklyn, New York 11245;

     Whereas, the Company has heretofore executed and delivered its General
Mortgage Indenture and Deed of Trust dated as of August 1, 1993 (the
"Original Indenture"), to the Trustee, for the security of the Bonds of the
Company issued and to be issued thereunder (the "Bonds"); and

     Whereas, the Company has heretofore executed and delivered to the
Trustee certain indentures supplemental to the Original Indenture dated as
of August 15, 1993 and as of August 1, 1995 and, contemporaneously
herewith, the Company has executed and delivered to the Trustee two certain
indentures dated as of September 1, 1995 relating to New Mortgage Bonds of
the 8.90% Series and New Mortgage Bonds of the 6.99% Series, respectively
(the Original Indenture, as supplemented and amended by the aforementioned
supplemental indentures and by this Supplemental Indenture being
hereinafter referred to as the "Indenture"); and

     Whereas, the Company desires to create a new series of Bonds to be
issued under the Indenture, to be known as New Mortgage Bonds, 8.824%
Series due 1998 (the "New Mortgage Bonds of the 8.824% Series"), which New
Mortgage Bonds of the 8.824% Series are to be issued in exchange for
certain other bonds of the Company of like tenor and amount that were
issued pursuant to a supplemental indenture to the Company's Indenture
dated August 1, 1940; and

     Whereas, the Company, in the exercise of the powers and authority
conferred upon and reserved to it under the provisions of the Indenture,
and pursuant to appropriate resolutions of the Board of Directors, has duly
resolved and determined to make, execute and deliver to the Trustee a
Supplemental Indenture in the form hereof for the purposes herein provided;
and

     Whereas, all conditions and requirements necessary to make this
Supplemental Indenture a valid, binding and legal instrument have been
done, performed and fulfilled and the execution and delivery hereof have
been in all respects duly authorized;

     Now, Therefore, This Indenture Witnesseth:

     That Northwestern Public Service Company, in consideration of the
exchange referred to above and ownership from time to time of the Bonds and
the service by the Trustee, and its successors, under the Indenture 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,
hereby covenants and agrees to and with the Trustee and its successors in
the trust under the Indenture, for the benefit of those who shall hold the
Bonds as follows:

                           Article I
       Description Of Bonds Of The 8.824% Series Due 1998

     Section 1.  The Company hereby creates a new series of Bonds to be
known as "New Mortgage Bonds, 8.824% Series due 1998."  The New Mortgage
Bonds of the 8.824% Series shall be executed, authenticated and delivered
in accordance with the provisions of, and shall in all respects be subject
to, all of the terms, conditions and covenants of the Indenture, as
supplemented and modified.

     The commencement of the first interest period for the New Mortgage
Bonds of the 8.824% Series shall be July 15, 1995.  The New Mortgage Bonds
of the 8.824% Series shall mature July 15, 1998, and shall bear interest at
the rate of 8.824% per annum, payable semi-annually on the fifteenth day of
January and the fifteenth day of July in each year.  The person in whose
name any of the New Mortgage Bonds of the 8.824% Series are registered at
the close of business on any record date (as hereinafter defined) with
respect to any interest payment date shall be entitled to receive the
interest payable on such interest payment date notwithstanding the
cancellation of such New Mortgage Bonds of the 8.824% Series upon any
transfer or exchange subsequent to the record date and prior to such
interest payment date; provided, however, that if and to the extent the
Company shall default in the payment of the interest due on such interest
payment date, such defaulted interest shall be paid as provided in Section
3.07(b) of the Indenture.

     The term "record date" as used in this Section with respect to any
interest payment date shall mean January 1 or July 1, as the case may be,
next preceding the semi-annual interest payment date, or, if such January 1
or July 1 shall be a legal holiday or a day on which banking institutions
in the Borough of Manhattan, The City of New York, State of New York, are
authorized by law to close, then the next preceding day which shall not be
a legal holiday or a day on which such institutions are so authorized to
close.

     Section 2.  The New Mortgage Bonds of the 8.824% Series shall be
issued only as registered Bonds without coupons of the denomination of
$1,000, or any integral multiple of $1,000, appropriately numbered.  The
New Mortgage Bonds of the 8.824% Series may be exchanged, upon surrender
thereof, at the agency of the Company in the Borough of Manhattan, The City
of New York, State of New York, for one or more new New Mortgage Bonds of
the 8.824% Series of other authorized denominations, for the same aggregate
principal amount, subject to the terms and conditions set forth in the
Indenture.

     New Mortgage Bonds of the 8.824% Series may be exchanged or
transferred without expense to the registered owner thereof except that any
taxes or other governmental charges required to be paid with respect to
such transfer or exchange shall be paid by the registered owner requesting
such transfer or exchange as a condition precedent to the exercise of such
privilege.

     Section 3.  The New Mortgage Bonds of the 8.824% Series and the
Trustee's Certificate of Authentication shall be substantially in the
following forms respectively:

          [Form Of Bond Of The 8.824% Series Due 1998]

              Northwestern Public Service Company
   (Incorporated under the laws of the State of South Dakota)
           New Mortgage Bond, 8.824% Series Due 1998

No. R-                                            $______________

     Northwestern Public Service Company, a corporation organized and
existing under the laws of the State of Delaware (the "Company", which term
shall include any successor corporation as defined in the Indenture
hereinafter referred to), for value received, hereby promises to pay to
__________ or registered assigns, the sum of __________ dollars on the
fifteenth day of July, 1998, in any coin or currency of the United States
of America which at the time of payment is legal tender for public and
private debts, and to pay interest thereon in like coin or currency from
July 15, 1995, payable semi-annually, on the fifteenth days of January and
July in each year, at the rate of 8.824% per annum, until the Company's
obligation with respect to the payment of such principal shall be
discharged as provided in the Indenture hereinafter mentioned.  The
interest so payable on any January 15 or July 15 will, subject to certain
exceptions provided in the Supplemental Indenture dated as of September 1,
1995, be paid to the person in whose name this Bond is registered at the
close of business on the immediately preceding January 1 or July 1, as the
case may be.  Both principal of, and interest on, this Bond are payable at
the agency of the Company in the Borough of Manhattan, The City of New
York, State of New York.

     This Bond shall not be entitled to any benefit under the Indenture or
any indenture supplemental thereto, or become valid or obligatory for any
purpose, until the form of certificate endorsed hereon shall have been
signed by or on behalf of The Chase Manhattan Bank (National Association),
the Trustee under the Indenture, or a successor trustee thereto under the
Indenture, or by an authenticating agent duly appointed by the Trustee in
accordance with the terms of the Indenture.

     The provisions of this New Mortgage Bond are continued on the reverse
hereof and such continued provisions shall for all purposes have the same
effect as though fully set forth at this place.

     In Witness Whereof, Northwestern Public Service Company has caused
this New Mortgage Bond to be signed (manually or by facsimile signature) in
its name by an Authorized Executive Officer, as defined in the Indenture,
and its corporate seal (or a facsimile thereof) to be hereto affixed and
attested (manually or by facsimile signature) by an Authorized Executive
Officer, as defined in the Indenture.

Dated:                        Northwestern Public Service Company


                              By
                                   Authorized Executive Officer
ATTEST:


     Authorized Executive Officer

                [Form of Trustee's Certificate]

     This is one of the Bonds of the series designated therein referred to
in the within-mentioned Indenture and Supplemental Indenture dated as of
September 1, 1995.

                                                       The Chase Manhattan
                              Bank (National Association), as Trustee


                              By
                                   Authorized Officer

                   [FORM OF REVERSE OF BOND]

     This New Mortgage Bond of the 8.824% Series is one of a duly
authorized issue of Bonds of the Company (the "Bonds"), of the series
hereinafter specified, all issued and to be issued under and equally
secured by a General Mortgage Indenture and Deed of Trust (the
"Indenture"), dated as of August 1, 1993, executed by the Company to The
Chase Manhattan Bank (National Association) (the "Trustee"), as Trustee, to
which Indenture and all indentures supplemental thereto reference is hereby
made for a description to the properties mortgaged and pledged, the nature
and extent of the security, the rights of registered owners of the Bonds
and of the Trustee in respect thereof, and the terms and conditions upon
which the Bonds are, and are to be, secured.  The Bonds may be issued in
series, for various principal sums, may mature at different times, may bear
interest at different rates and may otherwise vary as provided in the
Indenture.  This New Mortgage Bond of the 8.824% Series is one of a series
designated as the "New Mortgage Bonds, 8.824% Series Due 1998" (the "New
Mortgage Bonds of the 8.824% Series") of the Company issued under and
secured by the Indenture and described in the supplemental indenture dated
as of September 1, 1995 (the "Supplemental Indenture dated as of September
1, 1995"), between the Company and the Trustee, supplemental to the
Indenture.

     New Mortgage Bonds of the 8.824% Series, of which this is one, are
subject to redemption at the option of the Company and upon the notice and
in the manner and with the effect provided in the Indenture, all, but not
less than all, of the New Mortgage Bonds of the 8.824% Series may be
redeemed by the Company at any time, on or after July 15, 1996 and prior to
maturity, upon payment of the following percentages of the principal
amounts thereof:

     If redeemed during the twelve month period beginning the fifteenth day
of July of the year:

                         1996 ---------- 101.471%
                         1997 ---------- 100.000%

together with accrued interest to the redemption date.

     To the extent permitted by, and as provided in, the Indenture,
modifications or alterations of the Indenture, or of any indenture
supplemental thereof, and of the rights and obligations of the Company and
of the holders of the Bonds may be made with the consent of the Company by
an affirmative vote of the holders of a majority in aggregate principal
amount of the Bonds entitled to vote then outstanding, at a meeting of the
holders of the Bonds called and held as provided in the Indenture, and by
an affirmative vote of the holders of a majority in aggregate principal
amount of the Bonds of any series or any tranche or tranches of any series
entitled to vote then outstanding and affected by such modification or
alteration, in case one or more but less than all of the series of Bonds or
of any tranche or tranches of any series of Bonds then outstanding under
the Indenture are so affected; provided, however, that no such modification
or alteration shall be made which will affect the terms of payment of the
principal of, or interest or premium, if any, on this Bond.

     In case an Event of Default, as defined in the Indenture, shall occur,
the principal of all the New Mortgage Bonds of the 8.824% Series at any
such time outstanding under the Indenture may be declared or may become due
and payable, upon the conditions and in the manner and with the effect
provided in the Indenture.  The Indenture provides that such declaration
may be rescinded under certain circumstances.

                           Article II
        Issue Of New Mortgage Bonds Of The 8.824% Series

     Section 1.  The Company hereby exercises the right to obtain the
authentication of $15,000,000 principal amount of Bonds pursuant to the
terms of Section 4.03 of the Indenture.  All such Bonds shall be New
Mortgage Bonds of the 8.824% Series.

     Section 2.  Such New Mortgage Bonds of the 8.824% Series may be
authenticated and delivered prior to the filing for recordation of this
Supplemental Indenture.

                          Article III
                           Redemption

     Section 1.  The New Mortgage Bonds of the 8.824% Series shall, upon
the notice and in the manner and with the effect provided in Article Five
of the Original Indenture, as amended by Section 2 of this Article III, be
redeemable at any time, on or after July 15, 1996 and prior to maturity, at
the option of the Company, as a whole, upon payment of the following
percentages of the principal amounts thereof:

     If redeemed during the twelve month period beginning the fifteenth day
of July of the year:

                         1996 ---------- 101.471%
                         1997 ---------- 100.000%

together with accrued interest to the redemption date.

     Section 2.  Notice of redemption of any New Mortgage Bonds of the
8.824% Series shall be given as provided in Section 5.04 of the Original
Indenture.  If given by mail, the mailing of such notice shall be a
condition precedent to redemption, provided that any notice which is mailed
in the manner provided in Section 5.04 of the Original Indenture shall be
conclusively presumed to have been duly given whether or not the holders
receive such notice, and failure to give such notice by mall, or any defect
in such notice, to the holder of any such bond designated for redemption
shall not affect the validity of the redemption of any other such bond.
Except for the changes in the giving of notice of redemption as provided in
this Section, the procedures for redemption of the New Mortgage Bonds of
the 8.824% Series shall be as provided in Article Five of the Original
Indenture.

     Section 3.  The Company, with the approval of the Trustee, may enter
into a written agreement with the holder of any New Mortgage Bonds of the
8.824% Series providing that payment of such bonds called for redemption in
part only be made directly by mail, wire transfer or in any other manner to
the holder thereof without presentation or surrender thereof if there shall
be delivered to the Trustee an agreement (which may be a composite with
other such agreements) between the Company and such holder (or other person
acting as agent for such holder or for whom such holder is a nominee) that
payment shall be so made, and that in the event the holder thereof shall
sell or transfer any such bonds (a) it will, prior to the delivery of such
bonds, either (i) surrender such bonds to the Trustee to make a proper
notation of the amount of principal paid thereon or (ii) surrender such
bonds to the Trustee against receipt of one or more New Mortgage Bonds of
the 8.824% Series in an aggregate principal amount equal to the unpaid
principal portion of the bonds so surrendered, and (b) it will promptly
notify the Company of the name and address of the transferee of any New
Mortgage Bonds of the 8.824% Series so transferred.  The Trustee shall not
be liable or responsible to any such holder or transferee or to the Company
or to any other person for any act or omission to act on the part of the
Company or any such holder in connection with any such agreement.  The
Company will indemnify and save the Trustee harmless against any liability
resulting from any such act or omission and against any liability resulting
from any action taken by the Trustee in accordance with the provisions of
any such agreement.

                           Article IV
                          The Trustee

     The Trustee hereby accepts the trusts hereby declared provided, and
agrees to perform the same upon the terms and conditions in the Indenture
set forth and upon the following terms and conditions:

          The Trustee shall not be responsible in any manner
     whatsoever for or in respect of the validity or sufficiency of
     this Supplemental Indenture or the due execution hereof by the
     Company or for or in respect of the recitals contained herein,
     all of which recitals are made by the Company solely.  In
     general, each and every term and condition contained in Article
     Eleven 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 V
                    Miscellaneous Provisions

     This Supplemental Indenture may be simultaneously executed in any
number of counterparts, each of which when so executed shall be deemed to
be an original; but such counterparts shall together constitute but one and
the same instrument.

     In Witness Whereof, said Northwestern Public Service Company has
caused this Indenture to be executed on its behalf by an Authorized
Executive Officer as defined in the Indenture, and its corporate seal to be
hereto affixed and said seal and this Indenture to be attested by an
Authorized Executive Officer as defined in the Indenture; and The Chase
Manhattan Bank (National Association), in evidence of its acceptance of the
trust hereby created, has caused this Indenture to be executed on its
behalf by its President or one of its Vice Presidents and its corporate
seal to be hereto affixed and said seal and this Indenture to be attested
by its Secretary or one of its Assistant Secretaries; all as of the 1st day
of September, 1995.

                              Northwestern Public Service Company


                              By
                                        Vice President

(CORPORATE SEAL)

ATTEST:


     Corporate Secretary
                                                       The Chase Manhattan
                              Bank (National Association)


                              By
                                        Vice President

(CORPORATE SEAL)

ATTEST:


     Assistant Secretary

State Of South Dakota    )
                         )  SS
County Of Beadle         )


     Be it Remembered, that on this 1st day of September, 1995, before me,
Susan M. Anderson, a Notary Public within and for the County and State
aforesaid, personally came D. K. Newell, Vice President - Finance, and Alan
D. Dietrich, Corporate Secretary of Northwestern Public Service Company, a
Delaware corporation, who are personally known to me to be such officers,
and who are personally known to me to be the same persons who executed as
such officers the within instrument of writing, and such persons duly
acknowledged that they signed, sealed and delivered the said instrument as
their free and voluntary act as such Vice President - Finance and Corporate
Secretary, respectively, and as the free and voluntary act of Northwestern
Public Service Company for the uses and purposes therein set forth.

     In Witness Whereof, I have hereunto subscribed my name and affixed my
official seal on the day and year last above written.



(Notarial Seal)
                                             Susan M. Anderson
                                        Notary Public, Beadle County, S.D.
                                         My Commission expires June 8, 2000

State Of New York        )
                         )  SS
County Of Kings          )


     Be it Remembered, that on this _____ day of August, 1995, before me,
_______________, a Notary Public within and for the County and State
aforesaid, personally came _________________, Vice President, and
_________________, Assistant Secretary of The Chase Manhattan Bank
(National Association), a national banking association, who are personally
known to me to be such officers, and who are personally known to me to be
the same persons who executed as such officers the within instrument of
writing, and such persons duly acknowledged that they signed, sealed and
delivered the said instrument as their free and voluntary act as such Vice
President and Assistant Secretary, respectively, and as the free and
voluntary act of The Chase Manhattan Bank (National Association) for the
uses and purposes therein set forth.

     In Witness Whereof, I have hereunto subscribed my name and affixed my
official seal on the day and year last above written.



(Notarial Seal)
                                        Notary Public, State of New York
                                        No. __________
                                        Qualified in Kings County
                                        Commission expires ________, ____