<PAGE>

                                                                    EXHIBIT 4.25

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



               This Supplemental Indenture is, among other things,
                             A MORTGAGE OF CHATTELS



                         Southern California Gas Company


                                       TO


                     Wells Fargo Bank, National Association
                        (formerly American Trust Company)


                                     TRUSTEE


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


                             SUPPLEMENTAL INDENTURE
                   To Original Indenture dated October 1, 1940


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


                            DATED AS OF APRIL 1, 1982



================================================================================
<PAGE>

                                TABLE OF CONTENTS

                                                                            Page

PARTIES ...................................................................   1

RECITALS:
   Execution of Original Indenture and Supplements thereto ................   1
   Recording of Original Indenture and Supplements thereto ................   1
   Bonds heretofore issued ................................................   2
   Creation of Series P. due 1992 .........................................   2
   Lien on After Acquired Property ........................................   3
   Purpose of Supplemental Indenture ......................................   3
   Fulfillment of conditions precedent ....................................   4
   Consideration and Authorization ........................................   4

GRANTING CLAUSES:
   Real Property in California counties specified in Schedule A ...........   5
   Plant, system and utilities in specified counties and elsewhere ........   5
   Other properties now or hereafter owned ................................   6
   Excepted properties ....................................................   7

HABENDUM AND DECLARATION OF TRUST .........................................   7

                                   ARTICLE I.

               AMOUNT, FORM, NUMBERING DENOMINATION, TRANSFER AND
                    EXCHANGE OF BONDS OF SERIES P, DUE 1992.

SECTION 1.01.  Authorized amount of bonds of Series P, due 1992 ...........   8

SECTION 1.02.  Bonds of Series P, due 1992; issuable as fully registered
                 bonds; form of registered bonds and certificate ..........   8

SECTION 1.03.  Exchangeability of bonds ...................................  13

SECTION 1.04.  Offices or agencies for payment, registration, transfer and
                 exchange of bonds of Series P, due 1992 ..................  14

SECTION 1.05.  Certain conditions as to transfer, etc. of bonds of
                 Series P, due 1992 .......................................  14
<PAGE>

                                       ii

                                                                            Page

                                   ARTICLE II.

                       INTEREST, MATURITY DATE, REDEMPTION
                          AND CERTAIN OTHER PROVISIONS.

SECTION 2.01.  Interest rate, maturity date and places, and medium of
                 payment ..................................................  14

SECTION 2.02.  Redemption of bonds of Series P, due 1992 ..................  14

SECTION 2.03.  Renewal fund for bonds of Series P, due 1992 ...............  16

SECTION 2.04.  Other provisions of bonds of Series P, due 1992 ............  16

                                  ARTICLE III.

                               SUNDRY PROVISIONS.

SECTION 3.01.  Trustee not responsible for recitals; recordation of
                 Supplemental Indenture as required by law ................  16

SECTION 3.02.  Date of Supplemental Indenture and bonds of Series P, due
                 1992, are dates of identification ........................  16

SECTION 3.03.  Supplemental Indenture deemed to be part of Original
                 Indenture ................................................  17

SECTION 3.04.  Trustee accepts trusts on same terms expressed in Original
                 Indenture ................................................  17

SECTION 3.05.  Execution of Supplemental Indenture in counterpart .........  16

TESTIMONIUM ...............................................................  18

SIGNATURES AND SEALS ......................................................  18

ACKNOWLEDGMENTS ...........................................................  19

Schedule A ................................................................  21
<PAGE>

                                       1

               This Supplemental Indenture is, among other things,
                             A MORTGAGE OF CHATTELS

     THIS SUPPLEMENTAL INDENTURE, dated as of April 1, 1982, made and entered
into in the City of Los Angeles, State of California by and between SOUTHERN
CALIFORNIA GAS COMPANY, a corporation duly organized and existing under the laws
of the State of California, and having its principal place of business in the
City of Los Angeles, State of California (hereinafter sometimes called the
"Corporation"), and WELLS FARGO BANK, NATIONAL ASSOCIATION (formerly AMERICAN
TRUST COMPANY), a national banking association duly organized and existing under
and by virtue of the laws of the United States of America, and having its
principal place of business in the City and County of San Francisco, California
(hereinafter sometimes called the "Trustee").

                                   WITNESSETH:

     WHEREAS, the Corporation has executed and delivered to the Trustee a
certain Indenture (hereinafter sometimes called the "Original Indenture") dated
October 1, 1940, to secure bonds of the Corporation designated generally as its
"First Mortgage Bonds" to be issued from time to time in one or more series, any
of which series may vary from any other as to certain particulars specified in
Section 2.01 of the Original Indenture, and the Corporation has executed and
delivered to the Trustee Supplemental Indentures dated, respectively, as of July
1, 1947, May 1, 1948, June 1, 1950, April 1, 1952, August 1, 1955, June 1, 1956,
December 1, 1956, July 1, 1957, October 1, 1959, July 1, 1963, September 1,
1964, June 1, 1965, December 1, 1966, October 1, 1970, August 1, 1972, September
1, 1972, October 1, 1974, May 1, 1976, October 1, 1977, November 1, 1979,
February 1, 1981, and September 15, 1981 supplementing and amending the Original
Indenture (the Original Indenture together with this Supplemental Indenture and
all other supplemental indentures being herein collectively sometimes referred
to as the "Indenture"); and

     WHEREAS, the Original Indenture and said Supplemental Indentures dated,
respectively, as of July 1, 1947, May 1, 1948, June 1, 1950, April 1, 1952 and
August 1, 1955, are recorded in the office of the County Recorder of each of the
Counties listed below in the Official Records thereof, as stated in said
Supplemental Indenture
<PAGE>

                                       2

dated as of June 1, 1956; said Supplemental Indentures dated, respectively, as
of June 1, 1956 and December 1, 1956, are so recorded as stated in said
Supplemental Indenture dated as of July 1, 1957; said Supplemental Indenture
dated as of July 1, 1957 and each subsequently dated said Supplemental Indenture
(other than said Supplemental Indenture dated September 15, 1981) is so recorded
as stated in said Supplemental Indenture dated as of the next succeeding date;
and said Supplemental Indenture dated as of September 15, 1981 is recorded in
the offices of the County Recorders in the Counties of the State of California,
as follows:

<TABLE>
<CAPTION>
      County                      Reference                              Date
      ------                      ---------                              ----
<S>               <C>                                            <C>
Fresno            Official Records, Book 7792, Pages 95-121      September 25, 1981
Imperial          Official Records, Book 1475, pages 390-416     September 25, 1981
Kern              Official Records, Book 5406, Pages 1230-1306   September 24, 1981
Kings             Official Records, Book 1212, Pages 265-291     September 25, 1981
Los Angeles       Official Records, Document 81-957152           September 25, 1981
Orange            Official Records, Book 14231, Pages 750-776    September 25, 1981
Riverside         Official Records, Document 180822              September 25, 1981
San Bernardino    Official Records, Document 81-213198           September 25, 1981
San Diego         Official Records, Book 1981, Pages 1532-1558   September 25, 1981
San Luis Obispo   Official Records, Vol. 2358, Pages 314-340     September 25, 1981
Santa Barbara     Official Records, Document 81-39609            September 24, 1981
Tulare            Official Records, Vol. 1902, Pages 384-410     September 25, 1981
Ventura           Official Records, Document 091131              September 25, 1981
</TABLE>

     WHEREAS, bonds of the Corporation of eleven (11) series designated,
respectively, as its "First Mortgage Bonds, Series A, due 1982", "First Mortgage
Bonds, Series E, due 1988", "First Mortgage Bonds, Series F, due 1989", "First
Mortgage Bonds, Series G, due 1991", "First Mortgage Bonds, Series H, due 1995",
"First Mortgage Bonds, Series I, due 1997", "First Mortgage Bonds, Series K, due
1996", "First Mortgage Bonds, Series L, due 1997", "First Mortgage Bonds, Series
M, due 1999", "First Mortgage Bonds, Series N, due 2001", "First Mortgage Bonds,
Series O, due 2001", are outstanding as a part of the First Mortgage Bonds
referred to in the Original Indenture, each series of bonds, unless and until
the taking of further appropriate action by the Board of Directors of the
Corporation, being without limitation as to aggregate authorized principal
amount; and

     WHEREAS, pursuant to the provisions of Section 2.01 and 2.02 of the
Original Indenture, the Board of Directors of the Corporation has, by resolution
duly adopted and delivered to the Trustee, created, as a part of the First
Mortgage Bonds referred to in the Original Indenture,
<PAGE>

                                       3

a new series of bonds designated "First Mortgage Bonds, Series P, due 1992"
(herein sometimes called "bonds of Series P"), to be of the form, terms and
provisions provided in that resolution and herein, which new series of bonds,
unless and until the taking of further appropriate action by the Board of
Directors of the Corporation, is to be without limitation as to aggregate
authorized principal amount and of which series bonds in the aggregate principal
amount of $60,000,000 are to be presently issued; and

     WHEREAS, it is provided in the Original Indenture that all the business,
franchises and properties, real, personal and mixed, of every kind and nature
whatsoever and wheresoever situate, which might thereafter be acquired by the
Corporation, shall be as fully embraced within the lien thereof as if said
properties were owned by the Corporation at the date of the Original Indenture
and were particularly described therein and specifically conveyed thereby,
excepting certain properties expressly excepted by the provisions thereof; and

     WHEREAS, subsequent to the execution of the Original Indenture the
Corporation has acquired properties hereinafter mentioned or referred to, all of
which properties upon the acquisition thereof by the Corporation, became and now
are subject to the lien, operation and effect of the Original Indenture by
virtue of the after-acquired property clause or other clauses thereof; but the
Corporation, nevertheless, desires to execute, acknowledge, deliver and cause to
be recorded this Supplemental Indenture for the purposes, among others, of
expressly and specifically subjecting such after-acquired properties to the lien
of the Original Indenture as supplemented and of further assuring and confirming
the lien of the Original Indenture as supplemented on all of the properties of
every kind and character, whether real or personal and regardless of the date of
acquisition thereof by the Corporation, intended to be subjected to the lien
thereof; and

     WHEREAS, under the provisions of Section 2.02 and 16.01 of the Original
Indenture the Corporation and the Trustee are authorized to execute and deliver
an indenture supplemental to the Original Indenture (i) to set forth the
particulars permitted by Section 2.01 of the Original Indenture, as to which the
bonds of Series P are to vary from the bonds of the other series of said First
Mortgage Bonds, and (ii) for any purpose not inconsistent with the terms of the
Indenture; and
<PAGE>

                                       4

     WHEREAS, for and in consideration of the premises the Corporation desires
to execute this Supplemental Indenture; and

     WHEREAS, the making, executing, delivering and recording of this
Supplemental Indenture have been duly authorized by proper corporate action of
the Corporation; and

     WHEREAS, the execution and delivery of this Supplemental Indenture have
been authorized by the Public Utilities Commission of the State of California;

     NOW, THEREFORE, in consideration of the premises and of the sum of one
dollar ($1), lawful money of the United States of America, duly paid by the
Trustee to the Corporation, and of other good and valuable considerations,
receipt of which is hereby acknowledged, and in order (a) to set forth or
specify (i) the form of the fully registered bonds of Series P and the form of
the certificate to be endorsed on all bonds of said series, and (ii) the terms
and provisions of the bonds of Series P, including the particulars thereof which
vary from the bonds of the other series of said First Mortgage Bonds, and (b)
further to secure the payment of both the principal of and interest on the bonds
of the Corporation now or at any time hereafter outstanding under the Original
Indenture and/or any indenture supplemental thereto, including specifically, but
without limitation, all of said First Mortgage Bonds now outstanding and said
$60,000,000 aggregate principal amount of bonds of Series P, according to their
tenor and effect, and further to secure the observance and performance of all of
the covenants, agreements and conditions contained in the Original Indenture or
in any indenture supplemental thereto, and without in any way limiting the
generality or effect of the Indenture insofar as by any provision thereof of any
of the property therein or hereafter described or referred to is now subject or
intended to be subject to the lien and operation thereof, but to such extent
confirming such lien and operation, the Corporation has executed and delivered
this Supplemental Indenture and has granted, bargained, sold, released,
conveyed, mortgaged, assigned, transferred, pledged, set over and confirmed, and
does hereby grant, bargain, sell, release, convey, mortgage, assign, transfer,
pledge, set over and confirm unto Wells Fargo Bank, National Association, the
Trustee, and to its successor or successors in the trust created by the Original
Indenture and/or any indenture supplemental thereto,
<PAGE>

                                       5

and to its and their assigns, forever, with power of sale, subject, to the
extent applicable by the terms of the Indenture to any of the properties
hereinafter referred to or described, to the exceptions (other than exception
(f) set forth on page 67 of the Original Indenture and reading as follows: "(f)
Any gas and/or oil acreage, gas and/or oil wells, gas and/or oil reserves, or
gas and/or oil leaseholds hereafter acquired by the Corporation, or any property
or equipment now or hereafter owned by the Corporation and used for the
development of gas and/or oil acreage or for the drilling for or production of
gas and/or oil from such acreage"; which exception (f) is expressly made
inapplicable to certain parcels of property specified in the granting clauses of
said Supplemental Indentures dated respectively as of June 1, 1956, July 1,
1957, October 1, 1959, July 1, 1963, September 1, 1964, December 1, 1966,
October 1, 1970, September 1, 1972, October 1, 1974, May 1, 1976, October 1,
1977, November 1, 1979, February 1, 1981, and September 15, 1981), reservations,
conditions, terms and provisions provided in the Indenture with respect to
properties subject or intended to be subject thereto, all of the properties and
assets of the Corporation, real, personal and mixed, of every kind and
character, whether now or hereafter owned by the Corporation and wheresoever
situated, including, without in any way limiting or modifying the generality or
effect of the foregoing, all and singular, the following properties:

     FIRST: All of the lots, pieces and parcels of land and rights or interests
in real property situate in the Counties in the State of California,
specifically described and mentioned or enumerated in Schedule A attached
hereto, to which reference is hereby made and the same is made a part hereof
with the same force and effect as if the same were here set forth at length.

     SECOND: All and singular the plants, properties, equipment, real and
personal property, estates, interests, goodwill, generating, transmission,
feeding, storing and distribution systems, and utilities of the Corporation
situate in the Counties of Fresno, Imperial, Kern, Kings, Los Angeles, Orange,
Riverside, San Bernardino, San Diego, San Luis Obispo, Santa Barbara, Tulare and
Ventura, and elsewhere, in the State of California, with all and singular the
franchises, ordinances, grants, easements, licenses, powers, immunities,
permits, privileges, appurtenances, tenements and other rights and property
thereunto
<PAGE>

                                       6

appertaining or belonging, as the same now exist and as the same and any and all
parts thereof may hereafter exist or be improved, added to, enlarged, extended
or acquired in said counties or elsewhere in said state or any other state or
states.

     THIRD: All other property, real, personal and mixed, of every kind, nature
and description (including, without in any way limiting the effect of the
generality hereof, all facilities; all stocks, bonds and other securities from
time to time conveyed, assigned, transferred, mortgaged or pledged on behalf of
the Corporation, or with its consent, to the Trustee in the manner and for the
purposes as provided in the Indenture; all gas manufacturing plants, boilers,
engines, compressors, motors, pumps, generators, gasholders, tanks, appliances,
oil storage facilities, gas storage facilities, wells, buildings, structures,
plants, works and other improvements; all gas transmission and distributing
lines and systems; all meters and regulators and all other apparatus, machinery,
appliances, tools, furniture, fixtures, supplies, facilities and utilities and
other personal property; or any right or interest in any thereof; all business
and goodwill, rights, consents, franchises, ordinances, licenses, agreements,
contracts, permits, easements, rights of way, leases and leasehold interests;
powers, grants, privileges and immunities to construct, operate and maintain
lines and other facilities or properties for conveying gas or other commodities
or utilities for any purpose or purposes through, under and over public streets
or highways, or public or private places or property; all reversions,
remainders, tolls, incomes, revenues, earnings, rents, issues and profits of any
property, real, personal and mixed; and all other classes and types of property
described or referred to in the Original Indenture, or any indenture
supplemental thereto), now or hereafter owned, held, possessed, acquired or
enjoyed by or in any manner conferred upon or appertaining to the Corporation,
including the interest of the Corporation in all leases now or hereafter owned
by it, together with all and singular the tenements, hereditaments, and
appurtenances belonging or in any way appertaining to each and every part of any
and all property subject or intended to be subject to the lien and operation of
the Original Indenture as supplemented, and the reversion and reversions,
remainder and remainders, tolls, incomes, revenues, earnings, rents, issues and
profits thereof.
<PAGE>

                                       7

     SAVING AND EXCEPTING, however, from the property hereby mortgaged, conveyed
in trust and/or pledged, all property, whether now owned by the Corporation or
hereafter acquired by it, expressly saved and excepted from the lien of the
Indenture and therein referred to as the "excepted property" (except as
otherwise expressly provided with respect to exception (f) of said "excepted
property"), unless and until, upon the occurrence of an event of default under
the Indenture, the Trustee, or any receiver appointed thereunder, shall take
possession of any or all of such excepted property.

     TO HAVE AND TO HOLD in trust with power of sale for the equal and
proportionate benefit and security of all holders of bonds of the Corporation,
now or hereafter outstanding under the Indenture as from time to time in effect,
and for the enforcement and payment of said bonds and interest thereon when
payable, and the performance of and compliance with the covenants and conditions
of the Indenture as from time to time in effect, without any preference,
distinction or priority as to lien or otherwise of any of said bonds over any
others thereof by reason of the difference in the time of the actual issue, sale
or negotiation thereof, or for any other reason whatsoever, except as otherwise
expressly provided in the Indenture as from time to time in effect, so that each
and every such bond shall have the same lien and so that the principal and
interest of every such bond shall, subject to the terms thereof, be equally and
proportionately secured by said lien, as if such bond had been made, executed,
delivered, sold and negotiated simultaneously with the execution and delivery of
the Original Indenture.

     IT IS HEREBY COVENANTED, DECLARED, AND AGREED by and between the parties
hereto that all such bonds are issued, authenticated and delivered, or are to be
issued, authenticated and delivered, and that all property subject, or to become
subject, to the Original Indenture, including any indenture supplemental
thereto, is to be held, subject to the covenants, conditions, uses and trusts
therein set forth.

     It is hereby further stipulated and provided:
<PAGE>

                                       8

                                    ARTICLE I

                     AMOUNT, FORM, NUMBERING, DENOMINATION,
                         TRANSFER AND EXCHANGE OF BONDS
                             OF SERIES P, DUE 1992.

     SECTION 1.01. The bonds of Series P may be issued at any time or from time
to time upon and subject to the terms and provisions of the Indenture. Unless
and until the taking of further appropriate action by the Board of Directors of
the Corporation the bonds of said Series shall be without limitation as to
aggregate authorized principal amount.

     SECTION 1.02. The bonds of Series P shall be issued only as fully
registered bonds without coupons. The fully registered bonds without coupons and
the certificate of authentication to be endorsed on all bonds of said Series,
shall be substantially in the following form:

          (FORM OF REGISTERED BOND WITHOUT COUPONS, SERIES P, DUE 1992)

                         SOUTHERN CALIFORNIA GAS COMPANY
            (Incorporated under the laws of the State of California)

                     FIRST MORTGAGE BOND, SERIES P, DUE 1992
                                    (15 3/4%)

No. _____________                                               $ ____________

     SOUTHERN CALIFORNIA GAS COMPANY, a corporation organized and existing under
the laws of the State of California (hereinafter called the "Corporation", which
term shall include any successor corporation, as defined in the Indenture
hereinafter referred to), for value received, hereby promises to pay to
____________, or registered assigns, the sum of _______________________ DOLLARS
in lawful money of the United States of America, on the first day of April,
1992, and to pay interest thereon to the registered owner hereof from the date
of this bond, at the rate of 15 3/4% per annum in like lawful money, payable
semi-annually, on the first days of April and October in each year, commencing
October 1, 1982, until the Corporation's obligation with respect to the payment
of such principal shall be discharged as provided in the Indenture hereinafter
mentioned. Both the principal of and interest on this bond will be paid at the
principal office of Wells Fargo Bank, National Association, or its successor
trustee under said
<PAGE>

                                       9

Indenture, in the City and County of San Francisco, State of California or at
the main office of the Trustee in the City of Los Angeles, or, at the option of
the registered owner hereof, principal will be paid at the office of the
registered owner hereof, principal will be paid at the office or agency of the
Corporation in the City of New York, State of New York.

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

     IN WITNESS WHEREOF, SOUTHERN CALIFORNIA GAS COMPANY has caused this bond to
be signed in its corporate name by its authorized officer and its corporate seal
to be hereto affixed and attested by its Secretary or an Assistant Secretary.

     Dated as of ____________________, 19____

                                SOUTHERN CALIFORNIA GAS COMPANY

                                   By
                                       -----------------------------------
                                                   Controller

(CORPORATE SEAL)

ATTEST:


----------------------
     Secretary



                  (REVERSE SIDE FORM OF REGISTERED BOND WITHOUT
                          COUPONS, SERIES P, DUE 1992)

     This bond is one of a duly authorized issue of bonds of the Corporation
(herein called the "bonds"), of the series hereinafter specified, all issued and
to be issued under and all equally and ratably secured by a mortgage and deed of
trust dated October 1, 1940,
<PAGE>

                                       10

executed by the Corporation to Wells Fargo Bank, National Association (formerly
American Trust Company), as Trustee, to which mortgage and deed of trust and all
indentures supplemental thereto, including Supplemental Indentures dated,
respectively, as of July 1, 1947, August 1, 1955, June 1, 1956, December 1,
1956, June 1, 1965, August 1, 1972, May 1, 1976 and September 15, 1981 (herein
collectively referred to as the "Indenture"), reference is hereby made for a
description of the property conveyed in trust, mortgaged and pledged, the nature
and extent of the security, the rights of the registered owners of the bonds and
of the Trustee or trustees in respect thereof, the terms and conditions upon
which the bonds are, and are to be, secured and the circumstances under which
additional bonds may be issued. The bonds may be issued for various principal
sums, and may be issued in series, which may mature at different times, may bear
interest at different rates and may otherwise vary as in the Indenture provided.
This bond is one of a series designated as the "First Mortgage Bonds, Series P
due 1992" (herein called "bonds of Series P") of the Corporation, issued under
and secured by the Indenture.

     As provided in the Indenture, by any indenture or indentures supplemental
thereto executed by the Corporation and the Trustee and consented to by the
holders of not less than two-thirds (2/3) in principal amount of the bonds at
the time outstanding, and, in case one or more, but less than all, of the series
of bonds then outstanding are affected by such supplemental indenture, consented
to by the holders of at least two-thirds (2/3) in principal amount of bonds of
each series so affected, the Indenture or any indenture supplemental thereto,
and the rights and obligations of the Corporation and the holders of bonds, may
be modified or altered from time to time, as provided in the Indenture;
provided, however, (a) that the right of any holder of any bond to receive
payment of the principal of and interest on such bond, on or after the
respective due dates expressed in such bond, or to institute suit for the
enforcement of any such payment on or after such respective dates, shall not be
impaired or affected by any such supplemental indenture without the consent of
such holder, and (b) that no such modification or alteration shall reduce the
proportions of bondholders' consents required as aforesaid; such proportions to
be determined in each case as provided in the Indenture.
<PAGE>

                                       11

     The bonds of Series P are entitled to the benefits of the Renewal Fund as
provided in the Indenture.

     The bonds of Series P are subject to redemption at any time prior to
maturity at the option of the Corporation, either as a whole or in part, or
through operation of the Renewal Fund provided in the Indenture, upon payment of
the applicable redemption prices referred to hereunder. The redemption prices of
the bonds of Series P if redeemed at the option of the Corporation or through
operation of the Renewal Fund during the respective twelve-month periods
beginning April 1 in each of the years mentioned below, are set forth in the
following table in each case stated as a percentage of principal amount plus in
each case accrued interest to the date fixed for redemption.

            Year     Redemption Price        Year       Redemption Price
            ----     ----------------        ----       ----------------
            1982           115.00%           1987           104.29%
            1983           112.86            1988           102.15
            1984           110.72            1989           100.00
            1985           108.58            1990           100.00
            1986           106.43            1991           100.00

     Notwithstanding the foregoing, none of the bonds of Series P may be
redeemed prior to April 1, 1987 directly or indirectly from the proceeds of or
in anticipation of any refunding operation involving the incurring of debt which
has an interest cost to the Corporation of less than 16.056% per annum.

     Notice of redemption shall be given by publication once in each of three
separate calendar weeks in one daily newspaper printed in the English language
of general circulation in the Borough of Manhattan, City and State of New York,
and in one similarly printed daily newspaper of general circulation in the City
and County of San Francisco, California (the first of such publications to be
not less than thirty and not more than sixty days before the redemption date),
or, notice of any such redemption may be mailed to the registered owners of the
bonds to be redeemed not less than thirty nor more than sixty days before the
redemption date, in lieu of such notice being given by publication, all subject
to the conditions and as more fully set forth in the Indenture, including (1)
the condition that failure to give notice of any such redemption by mail, if
required, or any defect therein or in the mailing thereof shall not affect the
validity of the proceedings for
<PAGE>

                                       12

the redemption of any bonds so to be redeemed if notice by publication, if
required, is duly given and (2) the condition that, if any notice of redemption
of bonds shall state that it is subject to receipt by or for the account of the
Trustee on or before the date fixed for redemption of moneys applicable to and
sufficient for such redemption, such bonds shall not become due and payable by
virtue of such notice unless such moneys shall be held by or for the account of
the Trustee on or before the date fixed for redemption. If this bond or any
portion hereof is called for redemption and payment duly provided as specified
in the Indenture, interest shall cease to accrue on this bond or such portion
hereof from and after the date fixed for such redemption.

     In case an event of default, as defined in the Indenture, shall occur, the
principal of all bonds then outstanding under the Indenture may be declared or
become due and payable upon the conditions and in the manner and with the effect
provided in the Indenture.

     This bond is transferable by the registered owner hereof at the office or
agency of the Corporation in said City and County of San Francisco, in said City
of Los Angeles, in the Borough of Manhattan, City of New York and in such other
place or places as the Corporation may designate at any time or from time to
time, and thereupon a new fully registered bond or bonds of said series, without
coupons, of authorized denomination or denominations, of a like aggregate
principal amount, will be issued to the transferee or transferees in exchange
for this bond; and at any said offices or agencies fully registered bonds of
Series P, without coupons, are exchangeable for a like aggregate principal
amount of other such fully registered bonds of authorized denominations; all in
the manner and subject to the conditions as provided in the Indenture.

     No recourse shall be had for the payment of the principal of or the
interest on this bond or for any claim based hereon or on the Indenture or any
indenture supplemental thereto, against any incorporator, stockholder, director
or officer, past, present or future, of the Corporation, or of any predecessor
or successor corporation, either directly or through the Corporation, or any
such predecessor or successor corporation, whether by virtue of any
constitution, statute or rule of law, or by the enforcement of any assessment or
penalty, or otherwise, all such liability being waived and released by every
registered owner hereof by
<PAGE>

                                       13

the acceptance of this bond and as part of the consideration for the issue
hereof, and being likewise waived and released by the terms of the Indenture.

     This bond shall not become valid or obligatory for any purpose or be
entitled to any benefit under the Indenture until Wells Fargo Bank, National
Association, or its successor as Trustee under the Indenture, or an
authenticating agent, shall have signed the form of certificate endorsed hereon.

                     [FORM OF CERTIFICATE OF AUTHENTICATION]

                                   CERTIFICATE

     This bond is one of the bonds, of the series designated therein, described
in the within-mentioned Indenture.

         WELLS FARGO BANK,              or             BANKERS TRUST
       NATIONAL ASSOCIATION,                              COMPANY,
             Trustee                                Authenticating Agent


By                                          By
   -----------------------------                -----------------------------
        Authorized Officer                            Authorized Officer

      The bonds of Series P may contain or have imprinted thereon such
provisions or specifications not inconsistent with the Indenture as may be
required to comply with the rules of any stock exchange or any federal or state
authority or commission, or to comply with usage with respect thereto, and may
bear such other appropriate endorsements or notations as are authorized or
permitted by the Indenture.

      The fully registered bonds of Series P shall be issuable in denominations
of $1,000 and any multiple of $1,000 and shall be dated as provided in paragraph
1 of Section 2.01 of the Original Indenture . The definitive bonds of Series P
shall be numbered in such manner as the Corporation shall at any time or from
time to time determine.

      SECTION 1.03. In the manner and subject to certain conditions and
limitations specified herein and in the Indenture, bonds of Series P may be
exchanged without a service charge for a like aggregate
<PAGE>

                                       14

principal amount of such bonds of Series P of other authorized denomination or
denominations.

      SECTION 1.04. The Corporation shall maintain in the City and County of San
Francisco, and in the City of Los Angeles, State of California, and also in the
Borough of Manhattan, City of New York, State of New York, and in such other
place or places as the Corporation may designate at any time or from time to
time, an office or agency where bonds of Series P may be presented for payment,
registration, transfer and exchange as provided therein or in the Indenture.
Such office or agency in the City and County of San Francisco shall be the
principal office of the Trustee and such office or agency in the City of Los
Angeles shall be the main office of the Trustee in said City and such office of
agency in the Borough of Manhattan, City of New York shall be the principal
office of Banker Trust Company unless and until the Corporation shall designate
another office or agency by notice in writing delivered to the Trustee.

      SECTION 1.05. No transfer or exchange of any bonds of Series P pursuant to
any of the provisions of this Article I shall be made except upon and in
accordance with all of the applicable terms, provisions and conditions of said
bonds and of the Indenture.

                                   ARTICLE II

                       INTEREST, MATURITY DATE, REDEMPTION
                          AND CERTAIN OTHER PROVISIONS.

      SECTION 2.01. The bonds of Series P shall bear interest at the rate, shall
be expressed to mature as to principal and shall be payable as to principal and
interest at such place or places and in such money, all as provided in the form
of such bonds set forth in Section 1.02 hereof and by the applicable provisions
of the Indenture.

      SECTION 2.02. The bonds of Series P shall be subject to redemption, either
in whole or in part, at the applicable redemption prices specified in said form
of bonds, upon notice, in the manner and otherwise upon the terms and conditions
and with the effect, as provided herein and by the applicable provisions of the
Indenture, which provisions of the Indenture are hereby modified and
supplemented, but only with respect to the bond of Series P, as follows:
<PAGE>

                                       15

            (a) If at the time of publication or mailing of, or of otherwise
      giving, any notice of redemption of any of the bonds of Series P the
      Corporation shall not have deposited with the Trustee and/or irrevocably
      directed the Trustee to apply, from moneys held by it available to be used
      for the redemption of bonds of Series P, an amount in cash sufficient to
      redeem all of the bonds of Series P called for such redemption, including
      accrued interest to the date fixed for redemption, such notice shall state
      that it is subject to the receipt by the Trustee on or before the date
      fixed for redemption of moneys applicable to and sufficient for such
      redemption and that such notice shall be of no effect unless such moneys
      are so received on or before such date.

            (b) The Trustee, upon request of the Corporation evidenced by a
      resolution of its Board of Directors, shall, for and in behalf of and in
      the name of the Corporation, call for redemption bonds of Series P
      provided that, if cash sufficient for such redemption is not held by the
      Trustee at the time of such call, the notice shall state that it is
      subject to the receipt by the Trustee on or before the date fixed for
      redemption of moneys applicable to and sufficient for such redemption and
      that such notice shall be of no effect unless such moneys are so received
      on or before such date.

            (c) If bonds of Series P shall be called for redemption pursuant to
      a notice containing the statement set forth in subparagraph (a) or
      subparagraph (b) of this Section 2.02, the principal amount and premium,
      if any, of such bonds shall not become due and payable by virtue of such
      call or notice unless on or before the date fixed for redemption the
      Corporation shall have irrevocably deposited with the Trustee for the
      purpose for redeeming all of the bonds of Series P called for redemption,
      including funds for the payment of accrued interest to the date fixed for
      redemption, and/or irrevocably directed the Trustee to apply, from moneys
      held by it available to be used for the redemption of bonds of Series P an
      amount in cash sufficient to redeem all of the bonds of Series P called
      for redemption, including funds for the payment of accrued interest to the
      date fixed for redemption.

      Notwithstanding the foregoing, none of the bonds of Series P may be
redeemed prior to April 1, 1987 directly or indirectly from the proceeds of or
in anticipation of any refunding operation involving the
<PAGE>

                                       16

incurring debt which has an interest cost to the Corporation of less than
16.056% per annum.

      SECTION 2.03. The bonds of Series P shall be entitled to the benefits of
the Renewal Fund as provided in the Indenture.

      SECTION 2.04. The bonds of Series P shall, except as in this Supplemental
Indenture otherwise expressly provided, be on the terms and provisions, and
shall represent such rights and be entitled to such benefits, as are applicable
thereto by the terms of the Indenture.

                                   ARTICLE III

                                SUNDRY PROVISIONS

      SECTION 3.01. The recitals of fact contained herein shall be taken as the
statements of the Corporation, and the Trustee assumes no responsibility for the
correctness of the same. The Corporation hereby covenants and agrees that it
will cause this Supplemental Indenture to be kept recorded and/or filed as may
be required by law, in such manner and in such places as may be necessary fully
to preserve and protect the security of the bondholders and all of the rights of
the Trustee hereunder, and that it will with all reasonable dispatch deposit
with the Trustee counterparts of this Supplemental Indenture bearing official
notation or endorsements showing such recordation and/or filing, or in case such
counterparts are not returned to the Corporation, furnish to the Trustee the
best official evidence of such recordation and/or filing reasonably obtainable
by the Corporation, or evidence of the taking of such other action, if any, but
the Trustee, subject to the provisions of Section 14.02 and 14.03 of said
Original Indenture, shall in no wise be liable for any failure or omission in
this regard.

      SECTION 3.02. The date of this Supplemental Indenture and the date of the
bonds of Series P are intended as and for a date for the convenient
identification of this Supplemental Indenture and of the bonds of said series,
and are not intended to indicate that this Supplemental Indenture was executed
and delivered or that said bonds were executed, delivered or issued on said
date; it being hereby provided that this Supplemental Indenture may be executed
and delivered, and that said bonds may be executed, delivered or issued, either
on said date or before or after said date, and that this Supplemental Indenture
is in
<PAGE>

                                       17

fact executed and delivered by each party hereto on the date of its certificate
of acknowledgement hereto attached.

      SECTION 3.03. This Supplemental Indenture shall be deemed to be part of
the Original Indenture, and the Corporation agrees to conform to and comply with
all and singular the terms, provisions, conditions and covenants set forth
therein and herein. This Supplemental Indenture shall be construed in connection
with and as a part of the Original Indenture, as heretofore amended and
supplemented.

      SECTION 3.04. It is further agreed that the Trustee accepts the trust
imposed upon it by this Supplemental Indenture, upon and subject to the same
terms and conditions as are expressed in Article XIV of the Original Indenture.

      SECTION 3.05. In order to facilitate the recording of the Supplemental
Indenture, the same may be executed in several counterparts, each of which so
executed shall be deemed to be an original, and such counterparts shall
collectively constitute one and the same instrument
<PAGE>

                                       18

      IN WITNESS WHEREOF, Southern California Gas Company has caused this
Supplemental Indenture to be signed in its corporate name by its Chairman of the
Board or President or one of its Vice Presidents or the Controller and its
Secretary or one of its Assistant Secretaries, and its corporate seal to be
hereunto duly affixed, and Wells Fargo Bank, National Association, in token of
its acceptance of the trust hereby established, has caused this Supplemental
Indenture to be signed in its corporate name by one of its Authorized Officers
and its Secretary or one of its Assistant Secretaries, and its corporate seal to
be hereunto duly affixed, all as of April 1, 1982.


                                      SOUTHERN CALIFORNIA GAS COMPANY
Attest:

 /s/ VIRGINIA A. ROBINSON                 By  /s/ RICHARD W. DALBECK
-------------------------------              -------------------------------
                     Secretary                               Controller

(SEAL)
                                          WELLS FARGO BANK,
                                             NATIONAL ASSOCIATION
Attest:

  /s/ ROBERT T. DREILING                  By    /s/ CRAIG S. ELLIS
-------------------------------              -------------------------------
           Assistant Secretary                       Authorized Officer
(SEAL)
<PAGE>

                                       19

STATE OF CALIFORNIA          )
                             )      ss.
COUNTY OF LOS ANGELES        )


     On this 1st day of April, 1982, before me, BEVERLY D. BATES, a Notary
Public of the State of California, duly commissioned and sworn, personally
appeared RICHARD W. DALBECK, known to me to be the Controller, and VIRGINIA A.
ROBINSON, known to me to be the Secretary, of SOUTHERN CALIFORNIA GAS COMPANY,
one of the corporations named in and which executed the foregoing instrument,
known to me to be the persons who executed the within instrument on behalf of
said Corporation, and acknowledged to me that said Corporation executed the
same, and acknowledged to me that said Corporation executed the within
instrument pursuant to its by-laws or a resolution of its Board of Directors.

     IN WITNESS WHEREOF, I have hereunto set my hand and affixed my official
seal the day and year in this certificate first above written.


                                     /s/ BEVERLY D. BATES
                             --------------------------------------
                                        BEVERLY D. BATES

                                  Notary Public of the State of
                                           California

                                                                          (SEAL)

My Commission Expires March 30, 1985.
<PAGE>

                                       20

STATE OF CALIFORNIA          )
                             )      ss.
COUNTY OF SAN FRANCISCO      )


     On this 1st day of April, 1982, before me, DENIS J. MCCARTHY, a Notary
Public of the State of California, duly commissioned and sworn, personally
appeared CRAIG S. ELLIS, known to me to be an Authorized Officer, and ROBERT T.
DREILING, known to me to be an Assistant Secretary, of WELLS FARGO BANK,
NATIONAL ASSOCIATION, a national banking association, one of the corporations
named in and which executed the foregoing instrument, known to me to be the
persons who executed the within instrument on behalf of said Corporation, and
acknowledged to me that said Corporation executed the same, and acknowledged to
me that said Corporation executed the within instrument pursuant to its by-laws
or a resolution of its Board of Directors.

     IN WITNESS WHEREOF, I have hereunto set my hand and affixed my official
seal the day and year in this certificate first above written.


                                      /s/ DENIS J. MCCARTHY
                             --------------------------------------
                                        DENIS J. MCCARTHY

                                  Notary Public of the State of
                                           California

                                                                          (SEAL)

My Commission Expires April 11, 1983.
<PAGE>

                                       21

                                   SCHEDULE A

     Incorporated in and made a part of the Supplemental Indenture dated as of
April 1, 1982, by and between Southern California Gas Company and Wells Fargo
Bank, National Association, Trustee.

     The descriptive names or captions do not constitute a part of the property
descriptions, being used only for convenience of reference and identification.

     The term "Grantor" as used hereinafter refers to the grantor of each parcel
of property hereinafter described to Southern California Gas Company.

                              COUNTY OF LOS ANGELES

     Those certain lots, pieces and parcels of land and other property, rights,
and estates situate in the County of Los Angeles, State of California, described
as follows:

                         Northern Division Headquarters

     The Southeast 70 feet of the Northwest 200 feet of that portion of Lot 46
of Subdivision of Rancho La Canada, in the City of Los Angeles, County of Los
Angeles, State of California, as per Map recorded in Book 4, Page 351 of
Miscellaneous Records, in the office of the County Recorder of said County,
described as follows:

     Beginning at a point in the Northwesterly line of Tujunga Canyon Place
(formerly Honolulu Avenue) as described in Deed to County of Los Angeles,
recorded in Book 6242, Page 315 of Deeds, distant South 43(0) 07' 30" West
315.82 feet, measured along said Northwesterly line and the Northeasterly
prolongation thereof from the center line of Foothill Boulevard (formerly
Michigan Avenue) as shown on Map of Tract 4774, as per Map recorded in Book 113,
Pages 64 and 65 of Maps, Records of said County: thence North 48(0) 30' 30" West
along the Northeasterly line of the land described in Deed to Perley M. Finch
and wife, and Cressey R. Finch, recorded in Book 12495, Page 297, Official
Records, and recorded in Book 14295, Page 317, Official Records, 353.82 feet to
the Southerly corner of the land described in the Deed to Leon Bashein recorded
in Book 12865, Page 292, Official Records, and the true point of beginning;
thence North 43(0) 07' 30"East along the Southeasterly line thereof 232.10 feet
to the Southeasterly line of Foothill Boulevard as described in Deed recorded in
Book 11441, Page 205 of Official Records; thence South
<PAGE>

                                       22

53(0) 52' 30" East along said Southwesterly line, 261.64 feet to the
Northwesterly line of the 40 feet strip of land described in Parcel 64 of action
filed in Case No. 401203 of the Superior Court in and for said County; thence
South 38(0) 49' 20" West along said Northwesterly line 56.43 feet to the
beginning of a tangent curve therein concave to the Southeast, having a radius
of 1020 feet; thence Southwesterly along said curve, 202.60 feet to the
hereinbefore mentioned line, having a bearing of North 48(0) 30' 30" West;
thence along said last mentioned line 299.12 feet to the true point of
beginning.

                           General Offices and Garages

PARCEL 1:

      Lots 11 and 12 of Block 55 of the Huber Tract, in the City of Los Angeles,
      County of Los Angeles, State of California, as per Map recorded in Book 2,
      Page 280 of Miscellaneous Records, in the Office of the County Recorder of
      said County.

PARCEL 2:

      Lots 13 and 14 in Block 55 of the Huber Tract, City of Los Angeles, County
      of Los Angeles, State of California, as per Map recorded in Book 2, Page
      280 of Miscellaneous Records of said County.

      Excepting therefrom the North 4 feet of Lot 14, conveyed to Charles W.
      Baker by Deed recorded in Book 927, Page 91 of Deeds in the Office of the
      Los Angeles County Recorder.

                               COUNTY OF RIVERSIDE

     Those certain lots, pieces and parcels of land and other property, rights,
and estates situate in the County of Riverside, State of California, described
as follows:

                              Desert District Base

     Parcel 3 of Parcel May 18142, as per Map recorded in Book 100, Page 9 of
Parcel Maps, in the Office of the County Recorder in said County.

     Except therefrom, all mineral rights below a depth of 500 feet, with no
right of surface entry.
<PAGE>

                                RECORDATION DATA

     The foregoing Supplemental Indenture from Southern California Gas Company
to Wells Fargo Bank, National Association (formerly American Trust Company)
Trustee, dated as of April 1, 1982, was recorded in the following counties of
California (and indexed in each of said counties as a Deed, Mortgage, Trust
Deed, Assignment and Power of Attorney) on the respective dates and at the
respective places indicated in the following schedules:


        COUNTY                 REFERENCE                     DATE
        ------                 ---------                     ----

Fresno            Book 7885, Pages 610-634      Official Records  April 2, 1982

Imperial          Book 1482, Pages 1531-1555    Official Records  April 2, 1982

Kern              Book 5449, Pages 772-796      Official Records  April 2, 1982

Kings             Book 1227, Pages 883-907      Official Records  April 2, 1982

Los Angeles       Document 82-355255            Official Records  April 5, 1982

Orange            Document 82-117327            Official Records  April 5, 1982

Riverside         Document 56992                Official Records  April 5, 1982

San Bernardino    Document 82-065606            Official Records  April 5, 1982

San Diego         Book 1982, Pages 813-837      Official Records  April 2, 1982

San Luis Obispo   Vol. 2398, Pages 388-412      Official Records  April 2, 1982

Santa Barbara     Document 82-13400             Official Records  April 2, 1982

Tulare            Vol. 3952, Pages 481-505      Official Records  April 2, 1982

Ventura           Document 031824               Official Records  April 2, 1982