<PAGE>

                                                                   EXHIBIT 4.D.3

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




                          EL PASO ENERGY PARTNERS, L.P.
          EL PASO ENERGY PARTNERS FINANCE CORPORATION, AS THE ISSUERS,

                                       AND

             THE SUBSIDIARIES PARTY HERETO, AS SUBSIDIARY GUARANTORS

                                       AND

           JPMORGAN CHASE BANK, A NEW YORK STATE BANKING CORPORATION,
                             AS SUCCESSOR TRUSTEE TO
              CHASE BANK OF TEXAS, NATIONAL ASSOCIATION, AS TRUSTEE

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

                          EIGHTH SUPPLEMENTAL INDENTURE

                          DATED AS OF OCTOBER 10, 2002

                                       TO

                                    INDENTURE

                            DATED AS OF MAY 27, 1999

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


              10 3/8% SENIOR SUBORDINATED NOTES DUE 2009, SERIES A
              10 3/8% SENIOR SUBORDINATED NOTES DUE 2009, SERIES B


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

<PAGE>


                          EIGHTH SUPPLEMENTAL INDENTURE

         THIS EIGHTH SUPPLEMENTAL INDENTURE (this "Supplemental Indenture"),
dated as of October 10, 2002 is by and among El Paso Energy Partners, L.P., a
Delaware limited partnership (formerly Leviathan Gas Pipeline Partners, L.P.)
(the "Partnership"), El Paso Energy Partners Finance Corporation, a Delaware
corporation (formerly Leviathan Finance Corporation), the guarantor parties
hereto, and JPMorgan Chase Bank, a New York state banking corporation, as
successor trustee to the Chase Bank of Texas, National Association, as Trustee.

                              W I T N E S S E T H:

         WHEREAS, the Issuers, the Subsidiary Guarantors and the Trustee entered
into an Indenture, dated as of May 27, 1999 (as in effect on the date hereof,
the "Indenture"), relating to the 10 3/8% Senior Subordinated Notes due 2009,
Series A and the 10 3/8% Senior Subordinated Notes due 2009, Series B;

         WHEREAS, the Partnership desires to redesignate the subsidiaries of the
Partnership set forth on Schedule I attached hereto (the "NEW GUARANTORS") as
Restricted Subsidiaries and, accordingly, cause such subsidiaries to become
Subsidiary Guarantors under the Indenture pursuant to the terms of this
Supplemental Indenture;

         WHEREAS, this Supplemental Indenture is executed and delivered pursuant
to Sections 4.14 and 11.01 of the Indenture;

         WHEREAS, the Issuers, the Subsidiary Guarantors (which term includes
the New Guarantors) and the Trustee desire to enter into this Supplemental
Indenture to provide for the New Guarantors' guarantee of payment on the same
terms and conditions as the Guarantees by the other Subsidiary Guarantors; and

         WHEREAS, all conditions precedent provided for in the Indenture
relating to this Supplemental Indenture have been complied with.

         NOW, THEREFORE, in consideration of the premises herein contained, and
for other good and valuable considerations, the receipt and sufficiency of which
are hereby acknowledged, the Issuers, the Subsidiary Guarantors and the Trustee
mutually covenant and agree for the equal and proportionate benefit of all
Holders of the Notes as follows:

               SECTION 1. INCORPORATION OF INDENTURE; DEFINITIONS

         1.1 INCORPORATION OF INDENTURE. This Supplemental Indenture constitutes
a supplement to the Indenture, and the Indenture and this Supplemental Indenture
shall be read together and shall have effect so far as practicable as though all
of the provisions thereof and hereof are contained in one instrument.

         1.2 DEFINITIONS. All capitalized terms used herein and not otherwise
defined herein shall have the respective meanings assigned to such terms in the
Indenture.



<PAGE>


                       SECTION 2. SUPPLEMENTAL PROVISIONS

         2.1 UNCONDITIONAL GUARANTEE. Subject to the provisions of Article 11 of
the Indenture, the New Guarantors shall be Subsidiary Guarantors under the terms
of the Indenture and hereby unconditionally guarantee to each Holder of a Note
authenticated and delivered by the Trustee and to the Trustee and its successors
and assigns, irrespective of the validity and enforceability of the Indenture,
the Notes or the Obligations of the Issuers under the Indenture or the Notes,
that:

         (a)  the principal of, premium, interest and Liquidated Damages, if
              any, on the Notes shall be promptly paid in full when due, whether
              at the maturity or interest payment or mandatory redemption date,
              by acceleration, redemption or otherwise, and interest on the
              overdue principal of, premium, interest and Liquidated Damages, if
              any, on the Notes, if any, if lawful, and all other Obligations of
              the Issuers to the Holders or the Trustee under the Indenture and
              the Notes shall be promptly paid in full or performed, all in
              accordance with the terms of the Indenture and the Notes; and

         (b)  in case of any extension of time of payment or renewal of any
              Notes or any of such other obligations, that same shall be
              promptly paid in full when due or performed in accordance with the
              terms of the extension or renewal, whether at Stated Maturity, by
              acceleration or otherwise. Failing payment when due of any amount
              so guaranteed or any performance so guaranteed for whatever
              reason, the Subsidiary Guarantors shall be jointly and severally
              obligated to pay the same immediately.

         The New Guarantors hereby agree that their obligations hereunder and
under the Indenture shall be unconditional, irrespective of the validity,
regularity or enforceability of the Notes or the Indenture, the absence of any
action to enforce the same, any waiver or consent by any Holder of the Notes
with respect to any provisions of the Indenture and the Notes, the recovery of
any judgment against the Issuers, any action to enforce the same or any other
circumstance which might otherwise constitute a legal or equitable discharge or
defense of a Subsidiary Guarantor. The New Guarantors hereby waive diligence,
presentment, demand of payment, filing of claims with a court in the event of
insolvency or bankruptcy of the Issuers, any right to require a proceeding first
against the Issuers, protest, notice and all demands whatsoever and covenant
that the Guarantees shall not be discharged except by complete performance of
the obligations contained in the Notes and the Indenture.

         If any Holder or the Trustee is required by any court or otherwise to
return to the Issuers or Subsidiary Guarantors, or any custodian, trustee,
liquidator or other similar official acting in relation to either the Issuers or
Subsidiary Guarantors, any amount paid by either to the Trustee or such Holder,
these Guarantees, to the extent theretofore discharged, shall be reinstated in
full force and effect. The New Guarantors agree that they shall not be entitled
to any right of subrogation in relation to the Holders in respect of any
obligations guaranteed under the Indenture until payment in full of all
obligations guaranteed under the Indenture.

         The New Guarantors further agree that, as between the Subsidiary
Guarantors, on the one hand, and the Holders and the Trustee, on the other hand,
(x) the maturity of the Obligations


                                       2
<PAGE>

guaranteed under the Indenture may be accelerated as provided in Article 6 of
the Indenture for the purposes of these Guarantees, notwithstanding any stay,
injunction or other prohibition preventing such acceleration in respect of the
obligations guaranteed under the Indenture, and (y) in the event of any
declaration of acceleration of such Obligations as provided in Article 6 of the
Indenture, such Obligations (whether or not due and payable) shall forthwith
become due and payable by the Subsidiary Guarantors for the purpose of these
Guarantees. The New Guarantors agree that the Subsidiary Guarantors shall have
the right to seek contribution from any non-paying Subsidiary Guarantor so long
as the exercise of such right does not impair the rights of the Holders under
these Guarantees.

         2.2 OTHER GUARANTEE TERMS. The New Guarantors hereby confirm, adopt and
acknowledge each of the provisions of the Indenture relating to the Subsidiary
Guarantors and the Guarantees, including, but not limited to, Articles 4 and 11
thereof.

                            SECTION 3. MISCELLANEOUS

         3.1 COUNTERPARTS. This Supplemental Indenture may be signed in
counterparts and by the different parties hereto in separate counterparts, each
of which shall constitute an original and all of which together shall constitute
one and the same instrument.

         3.2 SEVERABILITY. In case any provision in this Supplemental Indenture
shall be invalid, illegal or unenforceable, the validity, legality and
enforceability of the remaining provisions shall not in any way be affected or
impaired thereby.

         3.3 HEADINGS. The headings of the sections of this Supplemental
Indenture have been inserted for convenience of reference only, are not to be
considered a part hereof and shall not modify or restrict any of the terms or
provisions hereof.

         3.4 SUCCESSORS. All agreements of the Issuers and the Subsidiary
Guarantors in this Supplemental Indenture shall bind their respective
successors. All agreements of the Trustee in this Supplemental Indenture shall
bind its successors.

         3.5 GOVERNING LAW. THIS SUPPLEMENTAL INDENTURE SHALL BE GOVERNED BY AND
CONSTRUED IN ACCORDANCE WITH THE LAWS OF THE STATE OF NEW YORK BUT WITHOUT
GIVING EFFECT TO APPLICABLE PRINCIPLES OF CONFLICTS OF LAW TO THE EXTENT THAT
THE APPLICATION OF THE LAWS OF ANOTHER JURISDICTION WOULD BE REQUIRED THEREBY.

         3.6 FULL FORCE AND EFFECT. The Indenture, as supplemented by this
Supplemental Indenture, remains in full force and effect and is hereby ratified
and confirmed as the valid and binding obligation of the parties hereto.

         3.7 TRUSTEE. The Trustee accepts the modifications of trusts referenced
in the Indenture and effected by this Supplemental Indenture. Without limiting
the generality of the foregoing, the Trustee assumes no responsibility for the
correctness of the recitals herein contained, which shall be taken as the
statements of the Issuers and the Subsidiary Guarantors, and the Trustee shall
not be responsible or accountable in any way whatsoever for or with respect to
the validity


                                       3
<PAGE>

or execution or sufficiency of this Supplemental Indenture, and the
Trustee makes no representation with respect thereto.

            [THE REMAINDER OF THIS PAGE IS INTENTIONALLY LEFT BLANK.]





                                       4

<PAGE>




         IN WITNESS WHEREOF, the parties hereto have executed this Supplemental
Indenture as of the date first above written.


EL PASO ENERGY PARTNERS, L.P.                   EL PASO ENERGY PARTNERS
     by its general partner                     FINANCE CORPORATION
     EL PASO ENERGY PARTNERS
     COMPANY

By:      /s/ D. Mark Leland                     By: /s/ D. Mark Leland
         --------------------------                 ----------------------------
Name:    D. Mark Leland                         Name:   D. Mark Leland
Title:   Senior Vice President and              Title:  Senior Vice President
         Controller                                     and Controller



JP MORGAN CHASE BANK, as successor trustee


By:      /s/ Rebecca A. Newman
         ---------------------------------------
Name:    Rebecca A. Newman
Title:   Vice President & Trust Officer







<PAGE>


NEW GUARANTORS:

El Paso offshore Gathering & Transmission, L.P.
El Paso Energy Warwink I Company, L.P.
El Paso Energy Warwink II Company, L.P.
El Paso Hub Services Company, L.L.C.
El Paso Indian Basin, L.P.
El Paso ENERGY Intrastate, L.P.
EPGT Texas Pipeline, L.P.
EPN Gathering and Treating Company, L.P.
EPN Gathering and Treating GP Holding, L.L.C.
EPN GP Holding, L.L.C.
EPN GP Holding I, L.L.C.
EPN Holding Company, L.P.
EPN Holding Company I, L.P.
EPN Pipeline GP Holding, L.L.C.
WARWINK GATHERING AND TREATING COMPANY
   By:   El Paso Energy Warwink I Company, L.P., its 99% partner and
         El Paso Energy Warwink II Company, L.P., its 1% partner

By:      /s/ Keith Forman
         ------------------------------------------
Name:    Keith Forman
Title:   Vice President and Chief Financial Officer




<PAGE>




Each of the undersigned hereby ratifies and confirms its respective obligations
under the Indenture, as supplemented by this Supplemental Indenture:

        ARGO, L.L.C.
        ARGO I, L.L.C.
        ARGO II, L.L.C.
        CHACO LIQUIDS PLANT TRUST
          By: El Paso Energy Partners Operating Company, L.L.C., its Trustee
        CRYSTAL HOLDING, L.L.C.
        DELOS OFFSHORE COMPANY, L.L.C.
        East Breaks Gathering Company, L.L.C.
        EL PASO ENERGY PARTNERS DEEPWATER, L.L.C.
        EL PASO ENERGY PARTNERS OIL TRANSPORT, L.L.C.
        EL PASO ENERGY PARTNERS OPERATING COMPANY, L.L.C.
        EPN NGL STORAGE, L.L.C.
        FIRST RESERVE GAS, L.L.C.
        FLEXTREND DEVELOPMENT COMPANY, L.L.C.
        GREEN CANYON PIPE LINE COMPANY, L.P.
        HATTIESBURG GAS STORAGE COMPANY
        HATTIESBURG INDUSTRIAL GAS SALES, L.L.C.
        High Island Offshore System, L.L.C.
        MANTA RAY GATHERING COMPANY, L.L.C.
        PETAL GAS STORAGE, L.L.C.
        POSEIDON PIPELINE COMPANY, L.L.C.
        VK DEEPWATER GATHERING COMPANY, L.L.C.
        VK-MAIN PASS GATHERING COMPANY, L.L.C.

               By:      /s/ D. Mark Leland
                        -------------------------------
               Name:    D. Mark Leland
               Title:   Senior Vice President and
                        Controller of each such entity



<PAGE>


                                   SCHEDULE I

El Paso Offshore Gathering & Transmission, L.P. , a Delaware limited partnership
El Paso Energy Warwink I Company, L.P. , a Delaware limited partnership
El Paso Energy Warwink II Company, L.P. , a Delaware limited partnership
El Paso Hub Services Company, L.L.C., a Delaware limited liability company
El Paso Indian Basin, L.P. , a Delaware limited partnership
El Paso Energy Intrastate, L.P. , a Delaware limited partnership
EPGT Texas Pipeline, L.P. , a Delaware limited partnership
EPN Gathering and Treating Company, L.P. , a Delaware limited partnership
EPN Gathering and Treating GP Holding, L.L.C. , a Delaware limited liability
   company
EPN GP Holding, L.L.C. , a Delaware limited liability company
EPN GP Holding I, L.L.C., a Delaware limited liability company
EPN Holding Company, L.P. , a Delaware limited partnership
EPN Holding Company I, L.P., a Delaware limited partnership
EPN Pipeline GP Holding, L.L.C. , a Delaware limited liability company
Warwink Gathering and Treating Company, a Delaware general partnership