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




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

                                       AND

             THE SUBSIDIARIES PARTY HERETO, AS SUBSIDIARY GUARANTORS

                                       AND

              CHASE BANK OF TEXAS, NATIONAL ASSOCIATION, AS TRUSTEE

                                   ----------

                          FOURTH SUPPLEMENTAL INDENTURE

                            DATED AS OF JULY 11, 2000

                                       TO

                                    INDENTURE

                            DATED AS OF MAY 27, 1999

                                   ----------

                                  $175,000,000

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


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



<PAGE>





                          FOURTH SUPPLEMENTAL INDENTURE

         THIS FOURTH SUPPLEMENTAL INDENTURE (this "Supplemental Indenture"),
dated as of July 11, 2000, is by and among El Paso Energy Partners, L.P., a
Delaware limited partnership (formerly Leviathan Gas Pipeline Partners, L.P.),
El Paso Energy Partners Finance Corporation, a Delaware corporation (formerly
Leviathan Finance Corporation), the guarantor parties hereto, and Chase Bank of
Texas, National Association, a national banking association, as trustee.

                                   WITNESSETH:

         WHEREAS, the Issuers (herein defined), the Subsidiary Guarantors
(herein defined) and the Trustee (herein defined) entered into an Indenture,
dated as of May 27, 1999 (as in effect on the date hereof, the "Indenture"),
relating to $175,000,000 of the Company's 10 3/8% Senior Subordinated Notes due
2009;

         WHEREAS, the Partnership (herein defined) has formed the Restricted
Subsidiaries (herein defined) Argo II, L.L.C. and El Paso Partners Acquisition,
L.L.C. (collectively, the "New Guarantors"), which will 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 Guarantor) and the Trustee desire to enter into this Supplemental
Indenture to provide for the New Guarantor's guarantee of the payment of
securities on the same terms and conditions as the Guarantees by the other
Subsidiary Guarantors;

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

         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 (herein defined) of the Notes (herein defined) 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.




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<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 guaranteed under the Indenture may be
accelerated as provided in Article 6 of the Indenture for the




                                       2
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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.

                            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
<PAGE>

         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 Company and the Subsidiary Guarantors, and the Trustee shall
not be responsible or accountable in any way whatsoever for or with respect to
the validity or execution or sufficiency of this Supplemental Indenture, and the
Trustee makes no representation with respect thereto.




                                       4
<PAGE>


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

EL PASO ENERGY PARTNERS,                       EL PASO ENERGY PARTNERS
L.P.                                           FINANCE CORPORATION



By: /s/ KEITH FORMAN                           By: /s/ KEITH FORMAN
   ---------------------------------              ------------------------------
Name:   Keith Forman                           Name:   Keith Forman
Title:  Chief Financial Officer                Title:  Chief Financial Officer


CHASE BANK OF TEXAS,
NATIONAL ASSOCIATION, as Trustee


By: /s/ MAURI J. COWEN
   ---------------------------------
Name:   Mauri J. Cowen
Title:  Vice President and
          Trust Officer


NEW GUARANTORS:


ARGO II, L.L.C.


By: /s/ KEITH FORMAN
   ---------------------------------
Name:   Keith Forman
Title:  Chief Financial Officer

EL PASO PARTNERS ACQUISITION, L.L.C.


By: /s/ KEITH FORMAN
   ---------------------------------
Name:   Keith Forman
Title:  Chief Financial Officer




<PAGE>



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

                            DELOS OFFSHORE COMPANY, L.L.C.
                            EWING BANK 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.
                            FLEXTREND DEVELOPMENT COMPANY, L.L.C.
                            GREEN CANYON PIPE LINE COMPANY, L.P.
                            MANTA RAY GATHERING COMPANY, L.L.C.
                            MORAY PIPELINE COMPANY, L.L.C.
                            POSEIDON PIPELINE COMPANY, L.L.C.
                            SAILFISH PIPELINE COMPANY, L.L.C.
                            TARPON TRANSMISSION COMPANY
                            VK DEEPWATER GATHERING COMPANY, L.L.C.
                            VK-MAIN PASS GATHERING COMPANY, L.L.C.



                            By: /s/ KEITH FORMAN
                                -------------------------------------------
                            Name:   Keith Forman
                            Title:  Chief Financial Officer of Each Such Entity