Exhibit (4a.(1))

                                                           [CONFORMED COPY]
                                                                 


                       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


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

                     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

                                   - 1 -

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:

                                   - 2 -

                                  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
   
                                  - 3 -
   
                              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
   
                                   - 4 -
   
         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

                                   - 5 -

         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

                                   - 6 -

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,

                                   - 7 -

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

                                   - 8 -

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

                                   - 9 -

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

                                  - 10 -

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

                                  - 11 -

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

                                  - 12 -

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   /s /Bruce R. DeBolt
                             ----------------------------
                             Senior Vice President and
                               Chief Financial Officer

                                  - 13 -

Attest:

    /s/ C. J. Rue
    ------------------
       Secretary

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


      /s/ P. L. Myers
    -------------------------



    /s/ Lou-Wayne Steiger
    -------------------------

                                  - 14 -

                        BANKERS TRUST COMPANY, as Trustee,



                        By   /s/ Samir Pandiri
                             --------------------------
                             Assistant Vice President

Attest:


    /s/ Shikha Dombek
    ---------------------
    Assistant Secretary



                               /s/ Stanley Burg
                           --------------------------
                           STANLEY BURG, as Trustee


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


/s/ Kenwyn Hackshaw           
- -----------------------------

/s/ John Florio               
- -----------------------------
                                  - 15 -

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.



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

                                  - 16 -


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

                                  - 17 -

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.


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

                                  - 18 -