Execution Version


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                            NORTHWESTERN CORPORATION
                   (SUCCESSOR TO NORTHWESTERN ENERGY, L.L.C.,
                  FORMERLY KNOWN AS THE MONTANA POWER, L.L.C.)


                                       TO


                              THE BANK OF NEW YORK


                                       AND


                               DOUGLAS J. MacINNES


                         As Trustees under Mortgage and
                   Deed of Trust, dated as of October 1, 1945,
                        with NorthWestern Energy, L.L.C.
                  (formerly known as The Montana Power, L.L.C.,
                successor by merger to The Montana Power Company)


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                      TWENTY-SECOND SUPPLEMENTAL INDENTURE


              Providing, among other things, for the assumption by
                NorthWestern Corporation of the due and punctual
               payment of all Bonds and performance and observance
         of all covenants and conditions of NorthWestern Energy, L.L.C.
                     under such Mortgage and Deed of Trust,
                          as amended and supplemented.


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                          Dated as of November 15, 2002




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                      TWENTY-SECOND SUPPLEMENTAL INDENTURE


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               THIS TWENTY-SECOND  SUPPLEMENTAL INDENTURE,  dated as of November
15, 2002, between NORTHWESTERN CORPORATION,  a corporation duly incorporated and
existing  under  the  laws of the  State of  Delaware  (hereinafter  called  the
"Company"),  having its principal  office at 125 S. Dakota  Avenue,  Suite 1100,
Sioux Falls,  South Dakota 57104, and THE BANK OF NEW YORK  (hereinafter  called
the  "Corporate  Trustee"),  a  corporation  of the  State  of New  York,  whose
principal corporate trust office is located at 101 Barclay Street, New York, New
York 10286  (successor to MORGAN  GUARANTY TRUST COMPANY OF NEW YORK)  (formerly
Guaranty Trust Company of New York), and DOUGLAS J. MACINNES,  whose post office
address is c/o The Bank of New York,  101  Barclay  Street,  New York,  New York
10286 (successor to Arthur E. Burke,  Karl R. Henrich,  H.H. Gould, R. Amundsen,
P.J. Crowley and W.T.  Cunningham)  (said Douglas J. MacInnes being  hereinafter
sometimes called the "Co-Trustee",  and the Corporate Trustee and the Co-Trustee
being hereinafter  together sometimes called the "Trustees"),  as Trustees under
the Mortgage and Deed of Trust, dated as of October 1, 1945 (hereinafter  called
the "Mortgage"  and,  together with any  indentures  supplemental  thereto,  the
"Indenture"),  which  Mortgage was executed and  delivered by The Montana  Power
Company,  a  corporation  of the State of New  Jersey  (hereinafter  called  the
"Company - New Jersey"), as predecessor by merger to NorthWestern Energy, L.L.C.
(hereinafter called "NorthWestern Energy"), formerly known as The Montana Power,
L.L.C., a limited liability company of the State of Montana (successor by merger
to The Montana Power Company, a corporation of the State of Montana (hereinafter
called the "Company-Montana")), to Guaranty Trust Company of New York and Arthur
E. Burke,  as  Trustees,  to secure the payment of bonds  issued or to be issued
under and in accordance with the provisions of the Mortgage,  reference to which
Mortgage is hereby made, this instrument  (hereinafter called the "Twenty-second
Supplemental Indenture") being supplemental thereto;

               WHEREAS, by the Mortgage,  the Company-New Jersey covenanted that
it would execute and deliver such supplemental  indenture or indentures and such
further  instruments and do such further acts as might be necessary or proper to
carry out more  effectually the purposes of the Indenture and to make subject to
the lien of the Indenture any property thereafter acquired,  made or constructed
and intended to be subject to the lien thereof; and

               WHEREAS,  the  Company-New  Jersey  executed and delivered to the
Trustees its First Supplemental Indenture,  dated as of May 1, 1954 (hereinafter
called  the  "First   Supplemental   Indenture")  and  its  Second  Supplemental
Indenture,   dated  as  of  April  1,  1959  (hereinafter   called  the  "Second
Supplemental Indenture"); and

               WHEREAS,   the   Company-New   Jersey   was   merged   into   the
Company-Montana  on November 30, 1961,  and to evidence  the  succession  of the
Company-Montana   to





the  Company-New  Jersey  and  the  assumption  by  the  Company-Montana  of the
covenants  and  conditions  of the  Company-New  Jersey  in the bonds and in the
Indenture  contained and to enable the  Company-Montana to have and exercise the
powers and rights of the  Company-New  Jersey under the  Indenture in accordance
with the terms  thereof,  the  Company-Montana  executed  and  delivered  to the
Trustees  its  Third  Supplemental  Indenture,  dated as of  November  30,  1961
(hereinafter called the "Third Supplemental Indenture"); and

               WHEREAS,  the  Company-Montana  executed  and  delivered  to  the
Trustees  its  Fourth  Supplemental  Indenture,   dated  as  of  April  1,  1970
(hereinafter called the "Fourth Supplemental Indenture"); its Fifth Supplemental
Indenture, dated as of April 1, 1971 (hereinafter called the "Fifth Supplemental
Indenture");  its  Sixth  Supplemental  Indenture,  dated as of  March  1,  1974
(hereinafter   called  the  "Sixth   Supplemental   Indenture");   its   Seventh
Supplemental  Indenture,  dated as of December 1, 1974  (hereinafter  called the
"Seventh Supplemental Indenture");  its Eighth Supplemental Indenture,  dated as
of July 1, 1975 (hereinafter called the "Eighth  Supplemental  Indenture");  its
Ninth Supplemental  Indenture,  dated as of December 1, 1975 (hereinafter called
the "Ninth Supplemental Indenture");  its Tenth Supplemental Indenture, dated as
of January 1, 1979 (hereinafter called the "Tenth Supplemental Indenture");  its
Eleventh Supplemental Indenture, dated as of October 1, 1983 (hereinafter called
the "Eleventh  Supplemental  Indenture");  its Twelfth  Supplemental  Indenture,
dated as of  January  1, 1984  (hereinafter  called  the  "Twelfth  Supplemental
Indenture"); its Thirteenth Supplemental Indenture, dated as of December 1, 1991
(hereinafter  called the "Thirteenth  Supplemental  Indenture");  its Fourteenth
Supplemental  Indenture,  dated as of  January 1, 1993  (hereinafter  called the
"Fourteenth  Supplemental  Indenture");  its Fifteenth  Supplemental  Indenture,
dated  as of March 1,  1993  (hereinafter  called  the  "Fifteenth  Supplemental
Indenture");  its  Sixteenth  Supplemental  Indenture,  dated as of May 1,  1993
(hereinafter  called the "Sixteenth  Supplemental  Indenture");  its Seventeenth
Supplemental  Indenture,  dated as of December 1, 1993  (hereinafter  called the
"Seventeenth  Supplemental  Indenture");  its Eighteenth Supplemental Indenture,
dated as of August 5, 1994  (hereinafter  called  the  "Eighteenth  Supplemental
Indenture");  its Nineteenth  Supplemental  Indenture,  dated as of December 16,
1999  (hereinafter  called the  "Nineteenth  Supplemental  Indenture");  and its
Twentieth  Supplemental  Indenture,  dated as of November  1, 2001  (hereinafter
called the "Twentieth Supplemental Indenture"); and

               WHEREAS,  the  Mortgage  and the First,  Second,  Third,  Fourth,
Fifth, Sixth, Seventh,  Eighth,  Ninth, Tenth,  Eleventh,  Twelfth,  Thirteenth,
Fourteenth,  Fifteenth,  Sixteenth,  Seventeenth,   Eighteenth,  Nineteenth  and
Twentieth  Supplemental  Indentures  were  recorded in the  official  records of
various counties and states as required by the Indenture; and

               WHEREAS,  an instrument  dated March 15, 1955 was executed by the
Company-New  Jersey  appointing  Karl R. Henrich as  Co-Trustee in succession to
said  Arthur E.  Burke,  resigned,  under the  Mortgage  and by Karl R.  Henrich
accepting the appointment as Co-Trustee under the Mortgage in succession to said
Arthur E. Burke, which instrument was recorded in various counties in the states
of Montana, Idaho and Wyoming; and


                                       2



               WHEREAS,  an  instrument  dated June 29, 1962 was executed by the
Company-Montana  appointing  H.H. Gould as Co-Trustee in succession to said Karl
R.  Henrich,  resigned,  under the  Mortgage  and by H.H.  Gould  accepting  the
appointment  as  Co-Trustee  under the  Mortgage in  succession  to said Karl R.
Henrich,  which  instrument  was  recorded in various  counties in the states of
Montana, Idaho and Wyoming; and

               WHEREAS,  an  instrument  dated June 22, 1973 was executed by the
Company-Montana  appointing R. Amundsen as Co-Trustee in succession to said H.H.
Gould, resigned, under the Mortgage and by R. Amundsen accepting the appointment
as  Co-Trustee  under the  Mortgage  in  succession  to said H.H.  Gould,  which
instrument was recorded in various counties in the states of Montana,  Idaho and
Wyoming; and

               WHEREAS,  an  instrument  dated July 1, 1986 was  executed by the
Company-Montana  appointing P.J.  Crowley as Co-Trustee in succession to said R.
Amundsen,  resigned,  under  the  Mortgage  and by  P.J  Crowley  accepting  the
appointment as Co-Trustee  under the Mortgage in succession to said R. Amundsen,
which  instrument  was  recorded  in various  counties in the states of Montana,
Idaho and Wyoming; and

               WHEREAS,   by  the   Eighteenth   Supplemental   Indenture,   the
Company-Montana  appointed  (i) W.T.  Cunningham  as Co-Trustee in succession to
said P.J. Crowley, resigned, under the Mortgage and W.T. Cunningham accepted the
appointment as Co-Trustee under the Mortgage in succession to said P.J. Crowley,
and (ii) The Bank of New York as  Corporate  Trustee  in  succession  to  Morgan
Guaranty Trust Company of New York, resigned, under the Mortgage and The Bank of
New York  accepted the  appointment  as Corporate  Trustee under the Mortgage in
succession to said Morgan Guaranty Trust Company of New York, which supplemental
indenture was recorded in various  counties in the states of Montana,  Idaho and
Wyoming; and

               WHEREAS,  an instrument  dated March 29, 1999 was executed by the
Company-Montana  appointing  Douglas J.  MacInnes as Co-Trustee in succession to
said W.T.  Cunningham,  resigned,  under the Mortgage and by Douglas J. MacInnes
accepting the appointment as Co-Trustee under the Mortgage in succession to said
W.T. Cunningham, which instrument was recorded in various counties in the states
of Montana, Idaho and Wyoming; and

             WHEREAS, in addition to the property described in the Mortgage, the
Company-Montana  has acquired  certain other  property,  rights and interests in
property; and

               WHEREAS,  the  Company-New  Jersey  or  the  Company-Montana  has
heretofore  issued,  in accordance  with the  provisions  of the  Mortgage,  the
following series of First Mortgage Bonds:




                                                         Principal
                                                          Amount           Principal Amount
                      Series                              Issued             Outstanding
                      ------                              ------             -----------
                                                                           
2-7/8% Series due 1975..........................         $40,000,000             NONE



                                       3






                                                         Principal
                                                          Amount           Principal Amount
                      Series                              Issued             Outstanding
                      ------                              ------             -----------
                                                                           
3-1/8% Series due 1984..........................           6,000,000             NONE
4-1/2% Series due 1989..........................          15,000,000             NONE
8-1/4% Series due 1974..........................          30,000,000             NONE
7-1/2% Series due 2001 (Fifth)..................          25,000,000             NONE
8-5/8% Series due 2004..........................          60,000,000             NONE
8-3/4% Series due 1981..........................          30,000,000             NONE
9.60% Series due 2005...........................          35,000,000             NONE
9.70% Series due 2005...........................          65,000,000             NONE
9-7/8% Series due 2009..........................          50,000,000             NONE
11-3/4% Series due 1993.........................          75,000,000             NONE
10/10-1/8% Series due 2004/2014.................          80,000,000             NONE
8-1/8% Series due 2014..........................          41,200,000             NONE
7.70% Series due 1999 (Fourteenth)..............          55,000,000             NONE
8-1/4% Series due 2007 (Fifteenth)..............          55,000,000            $365,000
8.95% Series 2002 (Sixteenth)...................          50,000,000           1,466,000
Secured Medium-Term Notes (Seventeenth).........          68,000,000          28,000,000
7% Series due 2005 (Eighteenth).................          50,000,000           5,386,000
6-1/8% Series due 2023 (Nineteenth).............          90,205,000          90,205,000
5.90% Series due 2023 (Twentieth)...............          80,000,000          80,000,000
0% Series due 1999 (Twenty-first)...............         210,321,007             NONE
7.30% Series due 2006 (Twenty-second)...........         150,000,000         150,000,000


which bonds are also  hereinafter  sometimes  called "Bonds of the First through
Twenty-second Series", respectively; and

               WHEREAS,  the Company-Montana  entered into an Agreement and Plan
of Merger,  dated as of February  20,  2001,  among the  Company-Montana,  Touch
America Holdings,  Inc. (a Delaware corporation and a wholly owned subsidiary of
the Company-Montana),  and NorthWestern Energy (under its then name, The Montana
Power,  L.L.C.),  a wholly owned  subsidiary  of Touch America  Holdings,  Inc.,
pursuant to which  agreement the  Company-Montana  was merged into  NorthWestern
Energy (under its then name, The Montana Power,  L.L.C.), on such terms as fully
preserve and in no respect  impair the lien or security of the  Indenture on the
mortgaged  property  or any of the  rights or powers of the  Trustees  or of the
bondholders thereunder; and

               WHEREAS,  NorthWestern Energy, under its then name of The Montana
Power, L.L.C.,  executed and delivered the Twenty-first  Supplemental Indenture,
dated as of February 13, 2002 (hereinafter called the "Twenty-first Supplemental
Indenture"), for the purpose of evidencing the succession of NorthWestern Energy
(under its then name, The Montana Power, L.L.C.) to the Company-Montana, and the
assumption  by  NorthWestern  Energy  (under its then name,  The Montana  Power,
L.L.C.)  of the  covenants  and  conditions  of the  Company-Montana  under  the
Indenture  and  any  bonds  then  issued  or to be  issued  thereunder,  and the
succession  of  NorthWestern  Energy  (under its then name,  The Montana  Power,
L.L.C.) to the powers and rights of the Company-Montana  under the Indenture and
any  bonds  now  issued  or to be  issued  thereunder,  in  accordance  with the
respective terms


                                       4



thereof which Twenty-first  Supplemental  Indenture was recorded in the official
records of various counties and states as required by the Indenture;

               WHEREAS,  the  Company-Montana  merged  with The  Montana  Power,
L.L.C. on February 13, 2002 and thereafter ceased to exist independently;

               WHEREAS,   The  Montana  Power,   L.L.C.   changed  its  name  to
NorthWestern Energy, L.L.C. on March 19, 2002;

               WHEREAS,  NorthWestern  Energy and the Company  have entered into
that certain Asset and Stock Transfer Agreement,  dated as of November 15, 2002,
providing for the transfer of substantially all of the assets as an entirety and
liabilities of  NorthWestern  Energy to the Company (the  "Transaction"),  which
Transaction is expected to be completed on or about the date hereof;

               WHEREAS,   the  Company  desires  to  execute  and  deliver  this
Twenty-second   Supplemental  Indenture  for  the  purposes  of  evidencing  the
assumption by the Company of the covenants and conditions of NorthWestern Energy
under the Indenture and any bonds now issued or to be issued thereunder, and the
succession of the Company to the powers and rights of NorthWestern  Energy under
the Indenture and any bonds now issued or to be issued thereunder, in accordance
with the respective terms thereof;

               WHEREAS,   the  Company  expects  to  record  this  Twenty-second
Supplemental Indenture in the official records of various counties and states as
required by the Indenture; and

             WHEREAS,  the  execution  and  delivery  by  the  Company  of  this
Twenty-second Supplemental Indenture have been duly authorized by the Company by
appropriate Resolutions.

               NOW, THEREFORE,  THIS INDENTURE WITNESSETH:  That the Company, in
consideration of the premises and of $1.00 to it duly paid by the Trustees at or
before the  ensealing  and delivery of these  presents,  the receipt  whereof is
hereby  acknowledged,  and in further evidence of assurance of the estate, title
and rights of the  Trustees  and in order  further to secure the payment of both
the  principal of and  interest  and premium,  if any, on the bonds from time to
time issued  under the  Indenture,  according  to their tenor and effect and the
performance of all the provisions of the Indenture  (including any  modification
made as in the Mortgage  provided) and of said bonds, and to confirm the lien of
the Mortgage, as heretofore  supplemented,  on certain after-acquired  property,
hereby  grants,  bargains,  sells,  releases,   conveys,   assigns,   transfers,
mortgages,  pledges,  sets over and  confirms  (subject,  however,  to  Excepted
Encumbrances   as  defined  in  Section  6  of  the   Mortgage,   as  heretofore
supplemented)  unto Douglas J. MacInnes,  the Co-Trustee,  and (to the extent of
its legal capacity to hold the same for the purposes  hereof) to The Bank of New
York,  the Corporate  Trustee,  as Trustees  under the  Indenture,  and to their
successor or successors in said trust, and to said Trustees and their successors
and assigns  forever,  all property,  real,  personal and mixed,  of the kind or
nature specifically mentioned in the


                                       5



Mortgage, as heretofore supplemented, or of any other kind or nature (whether or
not located in the State of Montana),  acquired by the Company after the date of
the execution and delivery of the Mortgage,  as heretofore  supplemented (except
any herein or in the Mortgage, as heretofore supplemented,  expressly excepted),
now owned or,  subject to the  provisions of subsection (I) of Section 87 of the
Mortgage,  as  heretofore  supplemented,  hereafter  acquired by the Company (by
purchase,  consolidation,  merger,  donation,  construction,  erection or in any
other way) and wheresoever  situated,  including (without in anywise limiting or
impairing by the  enumeration of the same the scope and intent of the foregoing,
or of any general  description  contained  in the  Indenture)  all lands,  power
sites,  flowage rights,  water rights,  water locations,  water  appropriations,
ditches, flumes, reservoirs, reservoir sites, canals, raceways, dams, dam sites,
aqueducts and all other rights or means for  appropriating,  conveying,  storing
and supplying  water; all rights of way and roads; all plants for the generation
of electricity by steam, water and/or other power; all powerhouses,  gas plants,
street  lighting  systems,  standards and other  equipment  incidental  thereto,
telephone, radio and television systems,  air-conditioning systems and equipment
incidental thereto, water works, water systems, steam heat and hot water plants,
substations,  lines, service and supply systems, bridges,  culverts, tracks, ice
or refrigeration plants and equipment,  offices,  buildings and other structures
and the equipment thereof, all machinery,  engines, boilers, dynamos,  electric,
gas and other machines,  regulators,  meters, transformers,  generators, motors,
electrical, gas and mechanical appliances,  conduits, cables, water, steam heat,
gas or other pipes,  gas mains and pipes,  service pipes,  fittings,  valves and
connections,  pole and transmission lines,  wires,  cables,  tools,  implements,
apparatus,  furniture and chattels;  all  franchises,  consents or permits,  all
lines for the transmission and distribution of electric current, gas, steam heat
or  water  for any  purpose  including  towers,  poles,  wires,  cables,  pipes,
conduits,  ducts and all  apparatus for use in  connection  therewith;  all real
estate, lands, easements, servitudes, licenses, permits, franchises, privileges,
rights of way and other rights in or relating to real estate or the occupancy of
the same and (except as herein or in the Mortgage,  as heretofore  supplemented,
expressly  excepted) all the right,  title and interest of the Company in and to
all other  property  of any kind or nature  appertaining  to and/or  used and/or
occupied and/or enjoyed in connection  with any property  hereinbefore or in the
Mortgage, as heretofore supplemented, described.

               TOGETHER  with all and  singular  the  tenements,  hereditaments,
prescriptions, servitudes and appurtenances belonging or in anywise appertaining
to  the  aforesaid  property  or  any  part  thereof,  with  the  reversion  and
reversions,  remainder and  remainders and (subject to the provisions of Section
57 of the  Mortgage)  the tolls,  rents,  revenues,  issues,  earnings,  income,
product and profits thereof,  and all the estate,  right, title and interest and
claim whatsoever,  at law as well as in equity, which the Company now has or may
hereafter acquire in and to the aforesaid property and franchises and every part
and parcel thereof.

               IT  IS  HEREBY  AGREED  by  the  Company  that,  subject  to  the
provisions  of  subsection  (I) of Section  87 of the  Mortgage,  as  heretofore
supplemented,  all the property,  rights and franchises  acquired by the Company
(by purchase, consolidation,  merger, donation, construction, erection or in any
other way) after the date  hereof,  except  any  herein


                                       6



or in the Mortgage, as heretofore supplemented, expressly excepted, shall be and
are as fully granted and conveyed  hereby and as fully embraced  within the lien
hereof and the lien of the  Mortgage,  as  heretofore  supplemented,  as if such
property,  rights  and  franchises  were  now  owned  by the  Company  and  were
specifically described herein and conveyed hereby.

               PROVIDED  that the  following  are not and are not intended to be
now  or  hereafter  granted,  bargained,  sold,  released,  conveyed,  assigned,
transferred,  mortgaged, hypothecated,  affected, pledged, set over or confirmed
hereunder and are hereby  expressly  excepted from the lien and operation of the
Mortgage,  as supplemented,  viz: (1) cash,  shares of stock,  bonds,  notes and
other  obligations  and  other  securities  not  specifically   pledged,   paid,
deposited,  delivered or held under the Mortgage, as supplemented, or covenanted
so to be; (2) merchandise,  equipment, apparatus, materials or supplies held for
the purpose of sale or other disposition in the usual course of business;  fuel,
oil and similar materials and supplies consumable in the operation of any of the
properties  of the Company;  all  aircraft,  tractors,  rolling  stock,  trolley
coaches, buses, motor coaches, automobiles, motor trucks, and other vehicles and
materials  and supplies held for the purpose of repairing or replacing (in whole
or part) any of the same; (3) bills, notes and accounts  receivable,  judgments,
demands  and  chooses  in  action,  and  all  contracts,  leases  and  operating
agreements not  specifically  pledged under the Mortgage,  as  supplemented,  or
covenanted so to be; the Company's  contractual  rights or other  interest in or
with respect to tires not owned by the Company;  (4) the last day of the term of
any  lease  or  leasehold  which  may be or  become  subject  to the lien of the
Mortgage,  as supplemented;  (5) electric energy,  gas, steam,  water,  ice, and
other  materials or products  generated,  manufactured,  produced,  purchased or
acquired by the Company for sale,  distribution or use in the ordinary course of
its business; all timber, minerals, mineral rights and royalties and all Gas and
Oil  Production  Property,   as  defined  in  Section  4  of  the  Mortgage,  as
supplemented;  (6) the  Company's  franchise  to be a  corporation;  and (7) any
property heretofore released pursuant to any provisions of the Indenture and not
heretofore  disposed  of  by  the  Company-New   Jersey,  the   Company-Montana,
NorthWestern  Energy or the Company;  provided,  however,  that the property and
rights  expressly  excepted  from the lien and  operation  of the  Mortgage,  as
supplemented,  in the  above  subdivisions  (2) and  (3)  shall  (to the  extent
permitted  by law) cease to be so  excepted in the event and as of the date that
either or both of the  Trustees  or a receiver  or trustee  shall enter upon and
take possession of the Mortgaged and Pledged  Property in the manner provided in
Article XIII of the Mortgage by reason of the occurrence of a Default as defined
in Section 65 thereof.

               TO HAVE AND TO HOLD  all  such  properties,  real,  personal  and
mixed, granted,  bargained,  sold, released,  conveyed,  assigned,  transferred,
mortgaged,  pledged,  set over or  confirmed  by the  Company as  aforesaid,  or
intended  so to be,  unto  DOUGLAS J.  MACINNES  and (to the extent of its legal
capacity to hold the same for the purposes hereto) unto THE BANK OF NEW YORK, as
Trustees, and their successors and assigns forever.

               IN TRUST  NEVERTHELESS,  for the same  purposes and upon the same
terms,  trusts and  conditions  and  subject to and with the same  provisos  and
covenants as are set forth in the Mortgage, as supplemented,  this Twenty-second
Supplemental Indenture being supplemental thereto.



                                       7



               AND IT IS HEREBY  COVENANTED  by the Company  that all the terms,
conditions,  provisos,  covenants and provisions  contained in the Mortgage,  as
supplemented,  shall affect and apply to the property hereinbefore described and
conveyed and to the estate,  rights,  obligations  and duties of the Company and
the Trustees and the  beneficiaries  of the trust with respect to said property,
and to the Trustees  and their  successors  as Trustees of said  property in the
same manner and with the same effect as if the said  property  had been owned by
the  Company-New  Jersey at the time of the execution of the  Mortgage,  and had
been  specifically and at length  described in and conveyed to the Trustees,  by
the Mortgage as a part of the property therein stated to be conveyed.

               SUBJECT  NEVERTHELESS,  to the limitation permitted by subsection
(I) of Section 87 of the Mortgage, as supplemented, namely, that notwithstanding
the  foregoing,  the  Mortgage,  as  supplemented,  shall not become or be or be
required to become or be a lien upon any of the  properties or  franchises  then
owned or thereafter acquired by the Company (by purchase, consolidation, merger,
donation, construction,  erection or in any other way) except (a) those acquired
by it from  NorthWestern  Energy,  and  improvements,  extensions  and additions
thereto and renewals and replacements thereof, (b) the property made and used by
the Company as the basis under any of the  provisions  of the  Indenture for the
authentication and delivery of additional bonds or the withdrawal of cash or the
release of property or a credit under Section 39 or Section 40 of the Indenture,
and (c) such  franchises,  repairs and  additional  property as may be acquired,
made  or  constructed  by  Company  (1) to  maintain,  renew  and  preserve  the
franchises  covered by the Indenture,  or (2) to maintain the property mortgaged
and intended to be  mortgaged  under the  Indenture  as an  operating  system or
systems in good repair,  working  order and  condition,  or (3) in rebuilding or
renewal  of  property,  subject  to the Lien  under the  Indenture,  damaged  or
destroyed,  or (4) in replacement of or substitution  for machinery,  apparatus,
equipment,  frames, towers, poles, wire, pipe, tools,  implements and furniture,
subject  to the Lien  thereunder,  which  shall  have  become  old,  inadequate,
obsolete, worn out, unfit, unadapted, unserviceable,  undesirable or unnecessary
for use in the operation of the property  mortgaged and intended to be mortgaged
thereunder.

               The Company further covenants and agrees to and with the Trustees
and their successors in said trust under the Indenture, as follows:

                                   ARTICLE I

                     Covenants and Agreements of the Company

               Section  1. The  Company  hereby  expressly  assumes  the due and
punctual  payment of the  principal and interest of all the bonds secured by the
Indenture  according  to their tenor and the due and  punctual  performance  and
observance of all of the covenants and conditions of the Indenture to be kept or
performed by NorthWestern  Energy,  and the Company herein expressly assumes and
agrees to pay, duly and  punctually,  the principal of and interest on the bonds
issued under the Indenture in accordance  with the  provisions of said bonds and
coupons and the  Indenture,  and agrees to perform and fulfill all the covenants
and conditions of the Indenture to be kept or performed by NorthWestern  Energy.
As  permitted


                                       8



by Section 86 of the Mortgage,  the Company shall be deemed to succeed to and be
substituted for NorthWestern Energy with the same effect as if it had been named
in the  Indenture,  and shall have and may exercise under the Indenture the same
powers and rights as NorthWestern Energy.

                                   ARTICLE II

                            Miscellaneous Provisions

               Section  1. The terms  defined  in the  Mortgage,  as  heretofore
supplemented,  shall,  for  all  purposes  of  this  Twenty-second  Supplemental
Indenture,   have  the  meaning   specified  in  the  Mortgage,   as  heretofore
supplemented.

               Section 2. The Trustees hereby accept the trusts herein declared,
provided,  created or supplemented  and agree to perform the same upon the terms
and conditions herein and in the Mortgage, as heretofore supplemented, set forth
and upon the following terms and conditions.

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

               Section 3. Whenever in this Twenty-second  Supplemental Indenture
any of the parties  hereto is named or referred  to, this shall,  subject to the
provisions of Articles XVI and XVII of the Mortgage, as heretofore supplemented,
be deemed to include  the  successors  and  assigns of such  party,  and all the
covenants and agreements in this Twenty-second  Supplemental Indenture contained
by or on  behalf of the  Company,  or by or on  behalf  of the  Trustees  shall,
subject  as  aforesaid,  bind  and  inure  to  the  respective  benefits  of the
respective successors and assigns of such parties, whether so expressed or not.

               Section 4. Nothing in this Twenty-second  Supplemental Indenture,
expressed or implied, is intended, or shall be construed,  to confer upon, or to
give to, any person, firm or corporation,  other than the parties hereto and the
holders of the bonds and coupons  Outstanding  under the  Indenture,  any right,
remedy or claim under or by reason of this Twenty-second  Supplemental Indenture
or any covenant,  condition,  stipulation,  promise or agreement hereof, and all
the  covenants,  conditions,  stipulations,  promises  and  agreements  in  this
Twenty-second  Supplemental  Indenture  contained by or on behalf of the Company
shall be for the sole and exclusive  benefit of the parties  hereto,  and of the
holders of the bonds and coupons now, or to be, Outstanding under the Indenture.



                                       9



               Section 5. This  Twenty-second  Supplemental  Indenture  shall be
executed in several counterparts,  each of which shall be an original and all of
which shall constitute but one and the same instrument.



                           [Signature Pages to Follow]



                                       10




               IN WITNESS WHEREOF,  NORTHWESTERN CORPORATION has caused its name
to be  hereunto  affixed,  and this  instrument  to be signed  and sealed by its
President  or one of its Vice  Presidents,  and its seal to be  attested  by its
Secretary or one of its  Assistant  Secretaries  for and in its behalf,  and THE
BANK OF NEW YORK, in token of its  acceptance of the trust hereby  created,  has
caused its  corporate  name to be hereunto  affixed,  and this  instrument to be
signed and sealed by one of its Vice  Presidents  or one of its  Assistant  Vice
Presidents,  and its corporate  seal to be attested by one of its Assistant Vice
Presidents,  Assistant  Secretaries  or  Assistant  Treasurers,  and  DOUGLAS J.
MACINNES, for all like purposes, has hereunto set his hand and affixed his seal,
as of the day and year first above written.

[Seal]

                                      NORTHWESTERN CORPORATION



                                      By:  /s/ Eric R. Jacobsen
                                          --------------------------------------
                                            Name:  Eric R. Jacobsen
                                            Title: SVP, General Counsel and CLO
Attest:

 /s/ Michael J. Young
 --------------------
Name:   Michael J. Young
Title:  Assistant Secretary



Executed, sealed and delivered by NORTHWESTERN CORPORATION in the presence of:


 /s/ Corinne Bohrer
 ------------------

 /s/ Karen L. Smook
 ------------------







        STATE OF SOUTH DAKOTA       )
                                      : ss.
        County of MINNEHAHA         )

               This  instrument was  acknowledged  before me on this 12th day of
        November,  2002, by Eric R. Jacobsen,  SVP,  General  Counsel and CLO of
        NORTHWESTERN CORPORATION, a Delaware corporation.


                                     /s/ Karen L. Smook
                                    ------------------------------------
                                    Print Name: Karen L. Smook
                                    Notary Public for the State of South Dakota
                                    Residing at Sioux Falls, South Dakota
                                    My Commission expires 7-12-2005

        [SEAL]






                                      THE BANK OF NEW YORK,
                                        as Corporate Trustee


                                      By:  /s/ MaryBeth Lewicki
                                           -------------------------
                                           Name:  MaryBeth Lewicki
                                           Title: Vice President




Attest:


 /s/ Stacey Poindexter
 ---------------------
Name:   Stacey Poindexter
Title:  Assistant Treasurer




                                       /s/ Douglas J. MacInnes
                                      ------------------------------------------
                                      DOUGLAS J. MACINNES, as Co-Trustee


Executed, sealed and delivered
by THE BANK OF NEW YORK and
DOUGLAS J. MACINNES in the presence of:



 /s/ Jeremy Finkelstein
 ----------------------

 /s/ Regina F. Johnson
 ---------------------







        STATE OF NEW YORK           )
                                      : ss.
        County of New York          )

               This  instrument was  acknowledged  before me on this 15th day of
        November, 2002, by MaryBeth Lewicki, Vice President of Bank of New York,
        a New York banking corporation.


                                          /s/ William J. Cassels
                                         ---------------------------------------
                                         Print Name:   William J. Cassels
                                         Notary Public for the State of New York
                                         Residing at Bronx County, New York
                                         My Commission expires May 18, 2006

        [SEAL]






        STATE OF NEW YORK           )
                                      : ss.
        County of New York          )

               This  instrument was  acknowledged  before me on this 15th day of
        November, 2002, by Douglas A. MacInnes.


                                          /s/ William J. Cassels
                                         ---------------------------------------
                                         Print Name:   William J. Cassels
                                         Notary Public for the State of New York
                                         Residing at Bronx County, New York
                                         My Commission expires May 18, 2006

        [SEAL]