<PAGE>

                                                                   EXHIBIT 4.E.1

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

                         GULFTERRA ENERGY PARTNERS, L.P.
              GULFTERRA ENERGY 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
   THE CHASE MANHATTAN BANK, A NEW YORK STATE BANKING CORPORATION, AS TRUSTEE

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

                          SIXTH SUPPLEMENTAL INDENTURE

                            DATED AS OF JUNE 20, 2003

                                       TO

                                    INDENTURE

                            DATED AS OF MAY 17, 2001

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

               8 1/2% SERIES A SENIOR SUBORDINATED NOTES DUE 2011
               8 1/2% SERIES B SENIOR SUBORDINATED NOTES DUE 2011

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

<PAGE>

                          SIXTH SUPPLEMENTAL INDENTURE

         THIS SIXTH SUPPLEMENTAL INDENTURE (this "SUPPLEMENTAL INDENTURE"),
dated as of June 20, 2003 is by and among GulfTerra Energy Partners, L.P, a
Delaware limited partnership (formerly El Paso Energy Partners, L.P.) (the
"PARTNERSHIP"), GulfTerra Energy Finance Corporation, a Delaware corporation
(formerly El Paso Energy Partners Financing Corporation), the guarantor parties
hereto, and JPMorgan Chase Bank, a New York state banking corporation, as
successor trustee to The Chase Manhattan Bank, a New York state banking
corporation, 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 17, 2001 (as in effect on the date hereof,
the "INDENTURE"), relating to the 8 1/2% Series A Senior Subordinated Notes due
2011 and the 8 1/2% Series B Senior Subordinated Notes due 2011;

         WHEREAS, the Partnership desires to designate Cameron Highway Pipeline
GP, L.L.C., a Delaware limited liability company, and Cameron Highway Pipeline
I, L.P., a Delaware limited partnership (each a "NEW GUARANTOR" and
collectively, the "NEW GUARANTORS"), as a Restricted Subsidiary and,
accordingly, cause such subsidiary to become a Subsidiary Guarantor 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 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.

                                        1

<PAGE>

                       SECTION 2. SUPPLEMENTAL PROVISIONS

         2.1 UNCONDITIONAL GUARANTEE. Subject to the provisions of Article 11 of
the Indenture, the New Guarantor shall be a Subsidiary Guarantor under the terms
of the Indenture and hereby, jointly and severally with the other Subsidiary
Guarantors, unconditionally guarantees 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 Guarantor hereby agrees
that to the fullest extent permitted by applicable law, its obligations 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. To the fullest extent permitted by applicable law, the New
Guarantor hereby waives 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 covenants 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 Guarantor agrees that it shall not be entitled to
any right of subrogation in relation to the Holders in respect of any
Obligations guaranteed by the Indenture until payment in full of all Obligations
guaranteed by the Indenture.

         The New Guarantor further agrees 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 by 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 by 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

                                        2

<PAGE>

payable by the Subsidiary Guarantors for the purpose of these Guarantees. The
New Guarantor agrees 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 Guarantor hereby confirms, adopts
and acknowledges 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. In addition, the Guarantee of the New Guarantor
contained herein that was incurred pursuant to Section 4.14 of the Indenture
shall be automatically and unconditionally released upon the release or
discharge of the guarantee which resulted in the creation of such Guarantee,
except a discharge or release by, or as a result of payment under, such
guarantee.

                            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.

                                      GULFTERRA ENERGY PARTNERS, L.P.

                                      GULFTERRA ENERGY FINANCE
                                      CORPORATION

                                      By:    /s/ James H. Lytal
                                             -----------------------------------
                                      Name:  James H. Lytal
                                      Title: President of each entity

                  Sixth Supplemental Indenture Signature Page 1

<PAGE>

                                      JP MORGAN CHASE BANK, as successor trustee


                                      By: /s/ Cary W. Gilliam
                                         ---------------------------------------
                                      Name:   Cary W. Gilliam
                                      Title:  Vice President

                  Sixth Supplemental Indenture Signature Page 2

<PAGE>

NEW GUARANTORS:

                                      CAMERON HIGHWAY PIPELINE GP, L.L.C.

                                      CAMERON HIGHWAY PIPELINE I, L.P.

                                      By:    /s/ James H. Lytal
                                             -----------------------------------
                                      Name:  James H. Lytal
                                      Title: President of each such entity

                  Sixth Supplemental Indenture Signature Page 3

<PAGE>

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

                CHACO LIQUIDS PLANT TRUST
                    By:  GULFTERRA ENERGY PARTNERS OPERATING COMPANY, L.L.C.,
                         in its capacity as trustee of the Chaco Liquids Plant
                         Trust
                CRYSTAL HOLDING, L.L.C.
                EL PASO ENERGY WARWINK I COMPANY, L.P.
                EL PASO ENERGY WARWINK II COMPANY, L.P.
                EL PASO OFFSHORE GATHERING & TRANSMISSION, L.P.
                EPN GATHERING AND TREATING COMPANY, L.P.
                EPN GATHERING AND TREATING GP HOLDING, L.L.C.
                FIRST RESERVE GAS, L.L.C.
                FLEXTREND DEVELOPMENT COMPANY, L.L.C.
                GULFTERRA ALABAMA INTRASTATE, L.L.C. (formerly EPN ALABAMA
                      INTRASTATE, L.L.C.)
                GULFTERRA FIELD SERVICES, L.L.C. (formerly EPN FIELD SERVICES,
                      L.L.C.)
                GULFTERRA GULF COAST, L.P. (formerly EPN GULF COAST, L.P.)
                GULFTERRA HOLDING I, L.L.C. (formerly EPN GP HOLDING I, L.L.C.)
                GULFTERRA HOLDING II, L.L.C. (formerly EPN GP HOLDING, L.L.C.)
                GULFTERRA HOLDING III, L.L.C. (formerly EPN PIPELINE GP HOLDING,
                      L.L.C.
                GULFTERRA HOLDING IV, L.L.C. (formerly EPN HOLDING COMPANY I, L.
                      P.)
                GULFTERRA HOLDING V, L.L.C. (formerly EPN HOLDING COMPANY, L.P.)
                GULFTERRA NGL STORAGE, L.L.C. (formerly EPN NGL STORAGE, L.L.C.)
                GULFTERRA INTRASTATE (formerly EL PASO ENERGY INTRASTATE, L.P.)
                GULFTERRA OIL TRANSPORT, L.L.C. (formerly EL PASO ENERGY
                      PARTNERS OIL TRANSPORT, L.L.C.)
                GULFTERRA OPERATING COMPANY, L.L.C. (formerly EL PASO ENERGY
                      PARTNERS OPERATING COMPANY, L.L.C.)
                GULFTERRA SOUTH TEXAS, L.P. (formerly EL PASO SOUTH TEXAS, L.P.)
                GULFTERRA TEXAS PIPELINE, L.P.(formerly EPGT TEXAS PIPELINE, L.
                      P.)
                HATTIESBURG GAS STORAGE COMPANY
                    By: FIRST RESERVE GAS, L.L.C., in its capacity as 50%
                        general partner of Hattiesburg
                    Gas Storage Company,
                    By: HATTIESBURG INDUSTRIAL GAS SALES, L.L.C., in its
                        capacity as 50% general partner
                    of Hattiesburg Gas Storage Company
                HATTIESBURG INDUSTRIAL GAS SALES, L.L.C.
                HIGH ISLAND OFFSHORE SYSTEM, L.L.C.
                    By: GULFTERRA ENERGY PARTNERS, L.P.,
                    its sole member
                MANTA RAY GATHERING COMPANY, L.L.C.
                PETAL GAS STORAGE, L.L.C.
                POSEIDON PIPELINE COMPANY, L.L.C.
                WARWICK GATHERING AND TREATING COMPANY
                    By: EL PASO ENERGY WARWINK I COMPANY, L.P., in its capacity
                        as 99% general partner
                        of Warwink Gathering and Treating Company,
                    By: EL PASO ENERGY WARWINK II COMPANY, L.P., in its capacity
                        as 1% general partner of Warwink Gathering and Treating
                        Company

                                      By:    /s/ James H. Lytal
                                             -----------------------------------
                                      Name:  James H. Lytal
                                      Title: President of each such entity

                  Sixth Supplemental Indenture Signature Page 4