Exhibit 4(c)
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                          NORTHWEST NATURAL GAS COMPANY


                                        TO


                              BANKERS TRUST COMPANY


                                       AND


            STANLEY BURG (SUCCESSOR TO R. G. PAGE AND J. C. KENNEDY),

                            As Trustees under the Mortgage and
                                      Deed of Trust, dated as of July 1, 1946,
                                      of  Portland  Gas  & Coke  Company  (now
                                      Northwest Natural Gas Company)





                         TWENTIETH SUPPLEMENTAL INDENTURE
                        PROVIDING, AMONG OTHER THINGS, FOR
                         FIRST MORTGAGE BONDS, DESIGNATED
                       SECURED MEDIUM-TERM NOTES, SERIES B


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



                             DATED AS OF JUNE 1, 1993


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                         TWENTIETH SUPPLEMENTAL INDENTURE

                  INDENTURE, dated  as of the 1st day  of June, 1993, made and
   entered into  by  and  between  NORTHWEST  NATURAL  GAS  COMPANY  (formerly
   Portland  Gas & Coke Company), a corporation  of the State of Oregon, whose
   post  office address  is  One  Pacific  Square,  220  N.W.  Second  Avenue,
   Portland, Oregon 97209 (hereinafter sometimes called the Company), party of
   the first  part, and BANKERS TRUST  COMPANY, a corporation of  the State of
   New York,  whose post office address  is Four Albany Street,  New York, New
   York 10006 (hereinafter sometimes called the Corporate Trustee) and STANLEY
   BURG (successor to R. G. PAGE and J. C. KENNEDY), whose post office address
   is c/o Bankers Trust Company, Four  Albany Street, New York, New York 10006
   (hereinafter sometimes called  the Co-Trustee), parties of  the second part
   (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 July 1, 1946 (hereinafter called the Mortgage), executed
   and delivered  by Portland Gas  & Coke Company  (now Northwest Natural  Gas
   Company) to secure the payment of bonds issued or to be issued under and in
   accordance with the provisions of the Mortgage, this indenture (hereinafter
   called Twentieth Supplemental Indenture) being supplemental thereto;

                  WHEREAS  the  Mortgage  was or  is  to  be  recorded in  the
   official records of various counties in the States of Oregon and Washington
   which counties include or will include all counties in which this Twentieth
   Supplemental Indenture is to be recorded; and

                  WHEREAS by the Mortgage the Company 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  Mortgage and to
   make subject to the lien of the  Mortgage any property thereafter acquired,
   made or constructed and intended to be subject to the lien thereof; and

                  WHEREAS the  Company executed and delivered  to the Trustees
   its First Supplemental  Indenture, dated  as of June  1, 1949  (hereinafter
   called  its  First   Supplemental  Indenture),   its  Second   Supplemental
   Indenture,  dated  as  of March  1,  1954  (hereinafter  called its  Second
   Supplemental  Indenture), its  Third  Supplemental Indenture,  dated as  of
   April 1,  1956 (hereinafter called  its Third Supplemental  Indenture), its
   Fourth Supplemental  Indenture, dated as  of February 1,  1959 (hereinafter
   called  its   Fourth  Supplemental   Indenture),  its   Fifth  Supplemental
   Indenture,  dated  as  of  July  1,  1961  (hereinafter  called  its  Fifth
   Supplemental  Indenture), its  Sixth  Supplemental Indenture,  dated as  of
   January 1, 1964  (hereinafter called its Sixth Supplemental Indenture), its
   Seventh  Supplemental Indenture,  dated as  of March  1, 1966  (hereinafter
   called  its  Seventh  Supplemental   Indenture),  its  Eighth  Supplemental
   Indenture,  dated as  of December  1, 1969  (hereinafter called  its Eighth
   Supplemental  Indenture), its  Ninth  Supplemental Indenture,  dated as  of
   April 1,  1971 (hereinafter called  its Ninth Supplemental  Indenture), its
   Tenth  Supplemental  Indenture, dated  as of  January 1,  1975 (hereinafter
   called  its   Tenth  Supplemental  Indenture),  its  Eleventh  Supplemental
   Indenture,  dated as of December  1, 1975 (hereinafter  called its Eleventh
   Supplemental Indenture),  its Twelfth  Supplemental Indenture, dated  as of
   July 1, 1981  (hereinafter called its Twelfth  Supplemental Indenture), its
   Thirteenth  Supplemental Indenture, dated  as of June  1, 1985 (hereinafter
   called  its Thirteenth Supplemental Indenture), its Fourteenth Supplemental
   Indenture,  dated as of November 1, 1985 (hereinafter called its Fourteenth
   Supplemental Indenture), its Fifteenth  Supplemental Indenture, dated as of
   July 1, 1986 (hereinafter called its Fifteenth Supplemental Indenture), its
   Sixteenth Supplemental Indenture, dated as of November 1, 1988 (hereinafter
   called its Sixteenth Supplemental Indenture), its Seventeenth  Supplemental
   Indenture,  dated as of October 1, 1989 (hereinafter called its Seventeenth
   Supplemental Indenture), and  its Eighteenth Supplemental  Indenture, dated
   as  of  July  1,  1990  (hereinafter  called  its  Eighteenth  Supplemental
   Indenture); and

                  WHEREAS   said   First   through   Eighteenth   Supplemental
   Indentures  were filed  for record,  and were  recorded  and indexed,  as a
   mortgage of both  real and  personal property, in  the official records  of
   various  counties in  the States  of Oregon  and Washington  which counties
   include or will include  all counties in which this  Twentieth Supplemental
   Indenture is to be recorded; and

                  WHEREAS the  Company executed and delivered  to the Trustees
   its   Nineteenth  Supplemental  Indenture,   dated  as  of   June  1,  1991
   (hereinafter called its Nineteenth Supplemental Indenture); and

                  WHEREAS said Nineteenth Supplemental Indenture was filed for
   record, and  was recorded  and  indexed, as  a mortgage  of  both real  and
   personal property,  and financing statements  were filed,  in the  official
   records of the several counties  and other offices in the States  of Oregon
   and Washington listed below, as follows:


  

                                      OREGON
                                      ------

                          Real Property Mortgage Records
                          ------------------------------


                                    Book, Film
   County        Date Recorded      or Reel            Page
   ------        -------------      ----------         ----

   Benton        June 14, 1991      M-135990-91        --
   Clackamas     June 14, 1991      91-28344           --
   Clatsop       June 14, 1991      760                836
   Columbia      June 14, 1991      91-3499            --
   Coos          June 14, 1991      91-06-0532         --
   Douglas       June 14, 1991      1140               373
   Hood River    June 18, 1991      911493             --
   Lane          June 17, 1991      9127918            --
   Lincoln       June 14, 1991      230                2261
   Linn          June 14, 1991      566                2
   Marion        June 14, 1991      861                37
   Multnomah     June 14, 1991      2424               970
   Polk          June 14, 1991      242                1891
   Tillamook     June 14, 1991      335                496
   Wasco         June 14, 1991      912001             --
   Washington    June 14, 1991      91030895           --
   Yamhill       June 14, 1991      F255P2185          --


                          Filed as a Financing Statement
                          ------------------------------


   Office                  Date Filed for Record               File No.
   ------                  ---------------------               --------

   Secretary of State      June 14, 1991                       P56754



   
                                    WASHINGTON
                                    ----------

                          Real Property Mortgage Records
                          ------------------------------


                                Book, Film
   County      Date Recorded    or Reel                Page
   ------      -------------    ----------             ----

   Clark       June 14, 1991    9106140143             --
   Klickitat   June 14, 1991      273                  904
   Skamania    June 18, 1991      123                  757


                          Filed as a Financing Statement
                          ------------------------------


   Office                  Date Filed for Record                File No.
   ------                  ---------------------                --------

   Secretary of State      June 17, 1991                         91-168-0134

                                                                
   

          WHEREAS an instrument dated as of June 14, 1951, was executed by the
   Company appointing J. C. KENNEDY as Co-Trustee in succession to  said R. G.
   PAGE (resigned)  under  the Mortgage  and by  J. C.  KENNEDY accepting  the
   appointment as  Co-Trustee under the Mortgage in  succession to the said R.
   G. PAGE, which instrument was recorded in various counties in the States of
   Oregon and Washington; and

          WHEREAS,  in  the  Ninth  Supplemental Indenture  STANLEY  BURG  was
   appointed by the Company as Co-Trustee under the Mortgage  in succession to
   said  J.  C. KENNEDY  (resigned) and  in  the Ninth  Supplemental Indenture
   STANLEY  BURG accepted such appointment as Co-Trustee under the Mortgage in
   succession to said J. C. KENNEDY; and

          WHEREAS  in addition to the  property described in  the Mortgage, as
   heretofore supplemented,  the Company has acquired  certain other property,
   rights and interests in property; and

          WHEREAS, the Company  has heretofore issued, in  accordance with the
   provisions of the Mortgage,  as supplemented, and on the date  hereof there
   remain outstanding, the following series of First Mortgage Bonds:

                                                      Principal Amount
   Series                                                Outstanding  
   ------                                             ----------------


   8-5/8% Series due 1996..................              $11,658,000
   9-3/8% Series due 2011..................              $46,000,000
   9.80% Series due 2018...................              $24,938,000
   9-1/8% Series due 2019..................              $25,000,000
   9-3/4% Series due 2015..................              $50,000,000
   Secured Medium-Term Notes, Series A.....              $50,000,000
   ; and


          WHEREAS Section 8  of the  Mortgage provides that  the form of  each
   series of  bonds (other than the  First Series) issued thereunder  shall be
   established  by Resolution of  the Board of Directors  of the Company; that
   the form of  such series, as established by said  Board of Directors, shall
   specify the descriptive title of the bonds and various other terms thereof;
   and that such Series may also contain such provisions not inconsistent with
   the  provisions of  the Mortgage  as  the Board  of Directors  may, in  its
   discretion, cause to  be inserted  therein expressing or  referring to  the
   terms and conditions upon which such bonds are to be  issued and/or secured
   under the Mortgage; and

          WHEREAS Section 120  of the Mortgage  provides, among other  things,
   that any power, privilege or right expressly or impliedly reserved to or in
   any way  conferred  upon the  Company  by any  provision of  the  Mortgage,
   whether  such power,  privilege or  right is  in any  way restricted  or is
   unrestricted, may (to the  extent permitted by law) be in whole  or in part
   waived  or surrendered  or subjected  to  any restriction  if  at the  time
   unrestricted or to  additional restriction if  already restricted, and  the
   Company  may enter into any further  covenants, limitations or restrictions
   for the benefit of  any one or more  series of bonds issued  thereunder, or
   the Company may cure any ambiguity contained therein or in any supplemental
   indenture  or may  (in lieu of  establishment by Resolution  as provided in
   Section 8 of the Mortgage) establish the terms and provisions of any series
   of bonds other than said First Series, by an instrument in writing executed
   and acknowledged  by the Company  in such manner  as would be  necessary to
   entitle a conveyance of real estate to record in all of the states in which
   any  property at  the time  subject to  the lien  of the Mortgage  shall be
   situated; and

          WHEREAS the Company now desires to create a new series  of bonds and
   (pursuant  to the provisions of Section 120 of  the Mortgage) to add to its
   covenants  and   agreements  contained  in  the   Mortgage,  as  heretofore
   supplemented, certain other covenants  and agreements to be observed  by it
   and to alter  and amend  in certain respects  the covenants and  provisions
   contained in the Mortgage, as heretofore supplemented and amended; and

          WHEREAS  the execution and delivery by the Company of this Twentieth
   Supplemental  Indenture, and  the terms  of the  bonds of  the Twenty-First
   Series hereinafter referred to, have been  duly authorized by the Board  of
   Directors  of the  Company  by appropriate  resolutions  of said  Board  of
   Directors;

          NOW, THEREFORE, THIS INDENTURE WITNESSETH:

          That  Northwest  Natural  Gas  Company,    in  consideration  of the
   premises and of One Dollar 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 assurance of the estate, title  and rights of
   the  Trustees, and  in order  further  to secure  the payment  both of  the
   principal of and  interest and premium, if  any, on the bonds from  time to
   time  issued under the Mortgage,  according to their  tenor and effect, and
   the  performance of  all  the provisions  of  the Mortgage  (including  any
   instruments  supplemental  thereto  and  any modification  made  as  in the
   Mortgage  provided)  and of  said  bonds, 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) unto  Stanley  Burg and  (to the  extent of  its legal
   capacity  to  hold  the same  for  the  purposes hereof)  to  Bankers Trust
   Company,  as Trustees  under  the  Mortgage,  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,  acquired by the
   Company after  the date of the Mortgage, of the kind or nature specifically
   mentioned  in Article XXI of  the Mortgage or  of any other  kind or nature
   (except any  herein or in  the Mortgage  expressly excepted) now  owned or,
   subject to  the provisions of subsection (I) of Section 87 of the Mortgage,
   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) all lands,
   gas plants, by-product plants, gas holders,  gas mains and pipes; all power
   sites, water rights, reservoirs, canals, raceways, dams, 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  power houses, street
   lighting  systems,  standards  and   other  equipment  incidental  thereto,
   telephone, radio,  television and  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,
   tracts, ice or  refrigeration plants and equipment,  offices, buildings and
   other  structures  and  the  equipment  thereof;  all  machinery,  engines,
   boilers,  dynamos, gas,  electric and  other machines,  regulators, meters,
   transformers,   generators,   motors,   gas,  electrical   and   mechanical
   appliances,  conduits,  cables, gas,  water,  steam  heat or  other  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 gas, electric current, steam heat  or water for any purpose
   including mains, pipes,  conduits, towers, poles, wires,  cables, 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 public or private property, real  or
   personal, or the occupancy of such property and (except as herein or in the
   Mortgage, as heretofore supplemented,  expressly excepted) all right, title
   and interest  the Company may now  have or may hereafter acquire  in and to
   any and all property of any kind or nature wheresoever situated.

          TOGETHER   WITH  all  and  singular  the  tenements,  hereditaments,
   prescriptions,  servitudes  and  appurtenances  belonging   or  in  anywise
   appertaining to the aforementioned  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
   aforementioned 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, 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  or in the Mortgage, as  heretofore supplemented,
   expressly  excepted, shall be and are  as fully granted and conveyed hereby
   and by the Mortgage,  and as fully embraced within the  lien hereof and the
   lien of  the Mortgage,  as supplemented,  as if such  property, rights  and
   franchises  were now owned by  the Company and  were specifically described
   herein  or in the Mortgage, as heretofore supplemented, and conveyed hereby
   or thereby.  Provided that the following are not and are not intended to be
   now or  hereafter granted,  bargained, sold, released,  conveyed, assigned,
   transferred,  mortgaged, pledged, set  over or confirmed  hereunder and are
   hereby expressly excepted  from the  lien and operation  of this  Twentieth
   Supplemental Indenture and from the lien  and operation of the Mortgage, as
   heretofore supplemented, viz: (1)  cash, shares of stock, bonds,  notes and
   other obligations and other  securities not hereafter specifically pledged,
   paid, deposited,  delivered  or  held  under the  Mortgage,  as  heretofore
   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  in  part)  any  of  the  same;  (3)  bills,  notes and  accounts
   receivable, judgments,  demands and choses  in action,  and all  contracts,
   leases  and  operating  agreements   not  specifically  pledged  under  the
   Mortgage, as heretofore supplemented, or covenanted so to be; (4) the  last
   day of the term of any lease or leasehold which may be or become subject to
   the  lien of  the Mortgage;  (5) gas,  petroleum, carbon,  chemicals, light
   oils, tar products, electric energy, steam, water, ice, and other materials
   or  products,  manufactured,  stored,  generated,  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 Natural Gas and Oil Production Property, as defined in Section 4 of
   the  Mortgage; and  (6)  the  Company's  franchise  to  be  a  corporation;
   provided, however, that the property and rights expressly excepted from the
   lien  and operation of this  Twentieth Supplemental Indenture  and from the
   lien  and operation  of the  Mortgage, as  heretofore 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  Stanley Burg  and (to  the extent  of its  legal
   capacity  to  hold  the same  for  the purposes  hereof)  to  Bankers Trust
   Company, 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 heretofore  supplemented,
   this Twentieth Supplemental Indenture being supplemental thereto.

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

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


                                    ARTICLE  I.

                          Twenty-First Series of Bonds.

          SECTION 1.0.1.      There shall  be  a series  of  bonds  designated
   "Secured  Medium-Term Notes, Series B" (herein sometimes referred to as the
   "Twenty-first Series"), each of which shall also bear the descriptive title
   "First Mortgage Bond", and the form thereof,  which shall be established by
   Resolution of the Board of Directors of the Company, shall contain suitable
   provisions  with respect  to  the matters  hereinafter  in this  Article  I
   specified.  Bonds  of the Twenty-first Series shall be  issued from time to
   time as fully  registered bonds  in denominations of  One Thousand  Dollars
   and, at  the option of  the Company,  in any multiple  or multiples  of One
   Thousand Dollars  (the  exercise of  such  option to  be evidenced  by  the
   execution and delivery thereof); each bond of the Twenty-first Series shall
   mature  on such date, shall bear interest  at such rate or rates (which may
   be either fixed  or variable) and have such other  terms and provisions not
   inconsistent with the  Mortgage as the Board of Directors  may determine in
   accordance  with a Resolution filed with the Corporate Trustee referring to
   this Twentieth Supplemental Indenture; interest on each bond of the Twenty-
   first Series which bears interest at either a fixed rate or a variable rate
   shall be payable on the dates which shall  be established prior to the date
   of first authentication  of such  bond and set  forth in  such bond and  at
   maturity (each an  interest payment date).   Notwithstanding the foregoing,
   so long as there shall be no existing default in the payment of interest on
   the  bonds of the Twenty-first  Series having the  same designated interest
   rate, interest payment dates and maturity, each of such bonds authenticated
   by the  Corporate Trustee  after the Record  Date for any  interest payment
   date for  such bonds, and prior  to such interest payment  date (unless the
   Issue  Date  is  after  such  Record Date),  shall  be  dated  the  date of
   authentication, but shall  bear interest from  such interest payment  date,
   and the person  in whose name such  bond shall have been  registered at the
   close of  business on such  Record Date  shall be entitled  to receive  the
   interest  payable  on  such  interest  payment  date,  notwithstanding  the
   cancellation  of such bond upon any transfer or exchange thereof subsequent
   to  such  Record Date  and  on  or prior  to  such  interest payment  date;
   provided,  that, (i) if the Issue Date  of bonds of the Twenty-first Series
   having the  same  designated  interest  rate, interest  payment  dates  and
   maturity  shall  be after  a  Record Date  and  prior to  the corresponding
   interest  payment date, such bonds shall bear interest from the Issue Date,
   but payment of  interest shall commence on the second interest payment date
   succeeding the Issue  Date, and (ii) interest payable on  the maturity date
   will be  payable to  the  person to  whom the  principal  thereof shall  be
   payable.   "Record Date" for  bonds of the  Twenty-first Series  having the
   same designated  interest rate, interest  payment dates and  maturity shall
   mean  (A) the date  which shall be  established prior to  the date of first
   authentication of such bonds and set forth in such bonds, or (B) if no such
   date shall  be established with respect to such bonds, the date 15 calendar
   days  prior to any interest payment date for such bonds.  "Issue Date" with
   respect  to bonds  of the  Twenty-first Series  having the  same designated
   interest  rate, interest payment dates and maturity shall mean (a) the date
   which shall  be established  prior to the  date of first  authentication of
   such  bonds and set forth  in such bonds,  or (b) if no  such date shall be
   established with respect to such bonds, the date of first authentication of
   such bonds.   The principal of, and premium,  if any, and interest on, each
   bond of the Twenty-first Series shall be payable at the office or agency of
   the Company 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  public and  private debts.   Bonds  of the  Twenty-first
   Series shall be dated as in Section 10 of the Mortgage provided.

          (I)  Bonds of  the Twenty-first Series shall be redeemable either at
   the option  of the Company or pursuant to the requirements of the Mortgage,
   in whole at  any time,  or, if specified  on the  face of any  bond of  the
   Twenty-first Series, in  part from time  to time,  prior to maturity,  upon
   notice, as provided in Section  52 of the Mortgage, mailed at  least thirty
   (30) days prior to the date fixed for redemption, as the Board of Directors
   may  determine in  accordance with  a Resolution  filed with  the Corporate
   Trustee  referring  to  this Twentieth  Supplemental  Indenture;  provided,
   however,  that bonds  of the  Twenty-first Series  shall not  be redeemable
   pursuant to Section 64 of the Mortgage.

         (II)  At the option of the registered owner, any bonds of the Twenty-
   first  Series, upon surrender thereof,  for cancellation, at  the office or
   agency  of the Company in  the Borough of Manhattan, The  City of New York,
   shall  (subject  to  the provisions  of  Section  12  of  the Mortgage)  be
   exchangeable for  a like aggregate  principal amount of  bonds of  the same
   series  of other authorized denominations  which have the  same Issue Date,
   maturity date, and redemption  provisions, if any, and which  bear interest
   at the same rate.

          Transfers  of  bonds of  the Twenty-first  Series may  be registered
   (subject to  the provisions of Section 12 of the Mortgage) at the office or
   agency of the Company in the Borough of Manhattan, The City of New York.

          Upon  any registration  of  transfer or  exchange  of bonds  of  the
   Twenty-first Series, the Company  may make a charge therefor  sufficient to
   reimburse it for any tax or taxes or other governmental charge, as provided
   in Section 12 of  the Mortgage, but the Company hereby  waives any right to
   make  a charge  in addition  thereto  for any  registration of  exchange or
   transfer of bonds of the Twenty-first Series.


                                    ARTICLE  II.

                            Miscellaneous Provisions.

          SECTION  2.0.1.   Subject  to the  amendments  provided for  in this
   Twentieth  Supplemental Indenture,  the terms defined  in the  Mortgage, as
   heretofore  supplemented,  shall,  for   all  purposes  of  this  Twentieth
   Supplemental Indenture,  have the  meanings specified  in the  Mortgage, as
   heretofore supplemented.

          SECTION  2.0.2.   The holders  of bonds  of the  Twenty-first Series
   consent that the Company  may, but shall not be obligated to,  fix a record
   date for  the purpose of  determining the holders  of bonds of  the Twenty-
   first  Series entitled to consent  to any amendment,  supplement or waiver.
   If a record  date is fixed, those  persons who were holders at  such record
   date (or their  duly designated proxies), and only those  persons, shall be
   entitled to consent  to such amendment, supplement  or waiver or to  revoke
   any consent  previously given, whether  or not such persons  continue to be
   holders  after  such record  date.    No such  consent  shall  be valid  or
   effective for more than 90 days after such record date.

          SECTION  2.0.3.    The  Trustees hereby  accept  the  trusts  hereby
   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, including the following:

          The Trustees shall not  be responsible in any manner  whatsoever for
   or in respect of the validity or sufficiency of this Twentieth 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 shall apply to
   and form part of  this Twentieth 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  Twentieth  Supplemental
   Indenture.

          SECTION 2.0.4.   Whenever  in this Twentieth  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, be  deemed to
   include the  successors or assigns of such party, and all the covenants and
   agreements in  this Twentieth  Supplemental  Indenture contained  by or  on
   behalf of the  Company or by or  on behalf of  the Trustees shall bind  and
   inure  to the  benefit of  the respective  successors and  assigns of  such
   parties whether so expressed or not.

          SECTION 2.0.5.   Nothing  in this Twentieth  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
   Mortgage, any right, remedy, or claim under or by reason  of this Twentieth
   Supplemental Indenture or any  covenant, condition, stipulation, promise or
   agreement hereof, and all the covenants, conditions, stipulations, promises
   and  agreements by  or  on  behalf of  the  Company as  set  forth in  this
   Twentieth  Supplemental  Indenture  shall be  for  the  sole  and exclusive
   benefit of the parties  hereto, and of the holders of the  bonds and of the
   coupons outstanding under the Mortgage.

          SECTION  2.0.6.   Except to the extent specifically provided herein,
   no provision  of  this  Twentieth Supplemental  Indenture  is  intended  to
   reinstate  any provisions in the Mortgage which were amended and superseded
   by  the  amendments to  the Trust  Indenture Act  of  1939 effective  as of
   November 15, 1990.

          SECTION  2.0.7.   This  Twentieth  Supplemental  Indenture has  been
   executed  in  several identical  counterparts, each  of  which shall  be an
   original and all of which shall constitute but one and the same instrument.

          IN  WITNESS WHEREOF, Northwest Natural  Gas Company, party hereto of
   the first part,  has caused its corporate name to  be hereunto affixed, and
   this instrument to be signed and sealed by its President or one of its Vice
   Presidents,  and its corporate seal to be  attested by its Secretary or one
   of its Assistant Secretaries for and in its behalf on the 14th day of June,
   1993, as of June 1,  1993, in Portland, Oregon; Bankers Trust  Company, one
   of the parties hereto of  the second part, 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  Secretaries on the
   14th day of  June, 1993, as of June  1, 1993, in The City of  New York; and
   Stanley Burg,  one of the parties  hereto of the second  part, has hereunto
   set his hand and affixed his seal, in The City of New York, on the 14th day
   of June, 1993, as of June 1, 1993.


                         NORTHWEST NATURAL GAS COMPANY



                         By Bruce R. DeBolt            
                           ____________________________
                            Senior Vice President and
                            Chief Financial Officer


   

   Attest:

          C. J. Rue             
   _____________________________
          Secretary

   Executed,  sealed and  delivered by  
   NORTHWEST NATURAL  GAS COMPANY  in the
   presence of:


          P. L. Myers                  
   ____________________________________


      Lou-Wayne Steiger                 
   _____________________________________



   
   
                         BANKERS TRUST COMPANY, as Trustee,



                         By  Samir Pandiri             
                           ____________________________
                              Assistant Vice President

   Attest:


     Shikha Dombek      
   _____________________
     Assistant Secretary



                                          Stanley Burg               
                                      _______________________________
                                      STANLEY BURG, as Trustee


   Executed, sealed and delivered 
   by BANKERS TRUST COMPANY and 
   STANLEY BURG in the presence of:


   Kenwyn Hackshaw       
   ______________________
                   
   John Florio            
   ________________________


   

   STATE OF OREGON            )
                              :  ss.:
   COUNTY OF MULTNOMAH        )

   June 14, A.D. 1993.


                  Before me  personally appeared  BRUCE R. DEBOLT,  who, being
   duly sworn,  did say that he  is Senior Vice President  and Chief Financial
   Officer, of NORTHWEST NATURAL GAS COMPANY  and that the seal affixed to the
   foregoing instrument is  the corporate  seal of said  Corporation and  that
   said  instrument was  signed and  sealed in  behalf of said  Corporation by
   authority of its Board of Directors; and he acknowledged said instrument to
   be its voluntary act and deed.

                  On  this 14th  day  of  June,  1993,  before  me  personally
   appeared BRUCE R. DEBOLT, to me known to be Senior Vice President and Chief
   Financial Officer of NORTHWEST NATURAL GAS COMPANY, one of the corporations
   that executed  the within and  foregoing instrument, and  acknowledged 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 he was
   authorized  to execute said  instrument and  that the  seal affixed  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.



                                            Virginia V. Burgess             
                                      ______________________________________

                                      Virginia V. Burgess
                                      Notary Public - Oregon
                                      Commission No. 004344
                                      My Commission Expires March 24, 1995



   

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

   June 14, A.D. 1993.


                  Before me personally appeared SAMIR PANDIRI, who, being duly
   sworn, did  say that  he is  an Assistant Vice  President of  BANKERS TRUST
   COMPANY  and that  the  seal affixed  to  the foregoing  instrument is  the
   corporate seal of said Corporation and that said instrument was signed  and
   sealed  in behalf  of  said  Corporation  by  authority  of  its  Board  of
   Directors; and he acknowledged  said instrument to be its voluntary act and
   deed.

                  On  this  14th  day  of June,  1993,  before  me  personally
   appeared SAMIR  PANDIRI, to me known  to be an Assistant  Vice President of
   BANKERS TRUST COMPANY, one of the corporations that executed the within and
   foregoing instrument, and acknowledged  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 he  was authorized  to execute
   said  instrument and that  the seal affixed  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.


                                        Marjorie Stanley         
                                      ___________________________
                                       
                                      Marjorie Stanley
                                      Notary Public, State of New York
                                      No. 41-4986405
                                      My Commission Expires 9/16/93


   

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


   June 14, A.D. 1993.


                  Before me personally appeared  the above-named STANLEY  BURG
   and acknowledged the foregoing instrument to be his voluntary act and deed.

                  On this day personally appeared before me STANLEY BURG to me
   known to  be the individual  described in and  who executed the  within and
   foregoing  instrument, and acknowledged that he signed the same as his free
   and voluntary act and deed, for the uses and purposes therein mentioned.

                  Given under my hand and official seal this 14th day of June,
   1993.


                                                 Marjorie Stanley          
                                           __________________________________
                                                 
                                           Marjorie Stanley
                                           Notary Public, State of New York
                                           No. 41-4986405
                                           My Commission Expires 9/16/93


   

   Recording Information:

                              IN THE STATE OF OREGON

                          Real Property Mortgage Records
                          -------------------------------

   Counterpart                                     Book, Film
       No.       County        Date Recorded         or Reel    Page
   -----------   ------        --------------      -----------  ----
       11        Benton        June 23, 1993       M-166017-93  -
                               June 29, 1993       M-166297-93  -
                                 (re-recorded)
       12        Clackamas     June 22, 1993       93-43287     -
       13        Clatsop       June 23, 1993       816          534
       14        Columbia      June 23, 1993       93-5185      -
       15        Coos          June 30, 1993       93061396     -
       32        Douglas       June 24, 1993       1241         840
       17        Hood River    June 23, 1993       932082       -
       18        Lane          June 23, 1993       9338274      -
       19        Lincoln       June 23, 1993       263          1293
       20        Linn          June 23, 1993       645          804
       21        Marion        June 24, 1993       1074         290
       22        Multnomah     June 23, 1993       2711         1885
       23        Polk          June 25, 1993       270          245
       24        Tillamook     June 23, 1993       351          718
       25        Wasco         June 23, 1993       932338       -
       26        Washington    June 23, 1993       93049394     -
       27        Yamhill       June 23, 1993       F288P1700    -


                          Filed as a Financing Statement
                          -------------------------------

   Counterpart
       No.             Office           Date Filed for Record   File No.
   ------------        ------           ---------------------   --------

       9         Secretary of State       June 23, 1993        R61325



                            IN THE STATE OF WASHINGTON

                          Real Property Mortgage Records
                          ------------------------------

   Counterpart                                   Book, Film
       No.        County       Date Recorded      or Reel       Page
   -----------    ------       -------------     ----------     ----

       29         Clark        June 24, 1993        399          1
       30         Klickitat    June 23, 1993        297          650
       31         Skamania     June 24, 1993        136          172


                          Filed as a Financing Statement
                          ------------------------------

   Counterpart
       No.           Office         Date Filed for Record     File No.
   -----------      ------         ---------------------     --------

       28      Secretary of State     June 25, 1993        93-176-0202