ALTALINK, L.P. CAPITAL MARKETS PLATFORM Seventh Supplemental Indenture Dated as of April 28, 2003

ALTALINK MANAGEMENT LTD., as general partner of ALTALINK, L.P ., a limited partnership created pursuant to the laws of the Province of Alberta

(hereinafter called the "Issuer")

ALTALINK MANAGEMENT LTD., a corporation incorporated under the laws of the Province of Alberta

(the "General Partner")

BMO TRUST COMP ANY, a trust company incorporated under the laws of Canada and authorized to carry on the business of a trust company in all of the provinces and territories of Canada

WHEREAS by an amended and restated master trust indenture dated as of the date hereof between the Issuer, the General Partner and the Trustee (the "Master Indenture") provision was made for the issuance of Supplemental Indentures to make additions to, deletions from or alterations of the provisions of the Master Indenture or Supplemental Indentures issued thereunder;

AND WHEREAS the Issuer has deemed it necessary and advisable to create and issue this Supplemental Indenture to alter certain provisions of the Master Indenture;

AND WHEREAS this Supplemental Indenture is executed pursuant to all necessary authorizations and resolutions of the Issuer to authorize the creation, issuance and delivery of the Supplemental Indenture and to establish the terms, provisions and conditions thereof;

AND WHEREAS the parties have entered into Supplemental Indentures and will, in the future, enter into further Supplemental Indentures which have, or will, authorize the issuance of the various series of Bonds to be secured by the charges created herein (such present and future Bonds being collectively called the "Outstanding Bonds");

AND WHEREAS this Supplemental Indenture is hereinafter sometimes referred to as the "Seventh Supplemental Indenture";

AND WHEREAS the foregoing recitals are made as representations and statements of fact by the Issuer and not the Trustee.

NOW THEREFORE THIS INDENTURE WITNESSES that consideration of the premises, the covenants and agreements herein contained and for other good and valuable consideration (the receipt and sufficiency of which are hereby acknowledged by each party), the parties hereof agree as follows:

The Seventh Supplemental Indenture is supplemental to the.Master Indenture and shall be read in conjunction therewith. Except only insofar as the Master. Indenture may be inconsistent with the express provisions of this Supplemental Indenture in which case the terms of this Supplemental Indenture shall govern and supersede those contained in the Master Indenture only to. the extent of such inconsistency,.this Seventh Supplemental Indenture shall henceforth have effect so far as practicable as if all the provisions of the Master Indenture and this Seventh Supplemental Indenture were contained in one instrument. The expressions used in this Seventh Supplemental Indenture which are defined in the Master Indenture shall, except as otherwise provided herein, have the respective meanings ascribed to them in the Master Indenture. Unless otherwise stated, any reference in this Seventh Supplemental Indenture to an Article, Section or Schedule shall be interpreted as a reference to the stated Article, Section of or Schedule to, the Master Indenture.

In consideration of the premises in this Indenture and of the sum of One Dollar ($1.00) paid to the Issuer by the Trustee (the receipt and sufficiency of which are hereby acknowledged) and to secure the due payment of the principal of and interest on the Outstanding Bonds, including interest on overdue interest and any premium payable under this Indenture and other monies from time to time owing under this Indenture, and the due performance and observance of the covenants,

agreements and obligations of the Issuer contained. in this Indenture and under the Outstanding Bonds (collectively the "Obligations"), the Issuer, subject to Permitted Encumbrances and the reservation of the last day of the term as hereinafter provided, does hereby:

TO HAVE AND TO HOLD the property, assets and undertaking subject to the Charge and rights hereby conferred on the Trustee for the use and purposes and with the power and authority and subject to the terms, conditions, provisos, covenants and stipulations expressed in the Master Indenture.

The Charge shall not extend or apply to the last day of the term of any lease, whether oral or written, now held or hereafter acquired by the Issuer but should such Charge become enforceable and the Trustee shall have determined to enforce the same, the Issuer shall thereafter stand possessed of such last day and shall hold it in trust to assign the same to any person who may acquire such term or the part thereof hereby charged in the course of any enforcement of the said Charge or any realization of the subject matter thereof. Further, the Charge does not and shall not extend to, and the Collateral shall.not include, any agreement, entitlement, right, franchise, licence or permit (the "Contractual Rights") to·which the Issuer is a party or of which the Issuer has the benefit, to the extent that the creation of the charge herein would constitute a breach of the terms of or permit any Person to terminate the Contractual Rights, but the Issuer shall hold its interest therein in trust for the Trustee for the benefit of the Bondholders forthwith upon obtaining the consent or approval of the other party thereto to create the Security Interest contemplated by this Indenture.

The Lien Hereof is for the equal and rateable benefit and security of all holders of the Outstanding Bonds which are secured in accordance with Section 5.1 of the Master Indenture, and the Trustee, without any priority or preference of any Outstanding Bond subject to the priority described in Section 5.3 thereof.

The following provisions shall apply to all Book Debts subject to the Lien Hereof:

"Book Debts" means all debts, accounts, claims, monies and chooses-in action which are now due, owing or accruing due or which may hereafter become due, owing and accruing due to the Issuer, including all claims of whatsoever nature or kind which the Issuer now has or may hereafter have for proceeds from any business interruption insurance.

Upon and so long as the Lien Hereof is enforceable, the Trustee may realize thereupon and enforce its right in the following manner:

be observed or performed any covenant, agreement, proviso or stipulation relating to any of the Collateral, when and to the extent the Trustee deems advisable;

the aggregate of the principal and interest owing on the Outstanding Bonds and all other monies and liabilities secured hereby (including costs and expenses incurred in connection with such disposition) and the proceeds of any such disposition;

payments received by the Issuer from and after the security hereby constituted becomes enforceable, shall be held by the Issuer in trust for the Trustee in the same medium in which received, shall not be commingled with any assets of the Issuer and shall, at the request of the Trustee, be turned over to the Trustee not later than the next business day following the day of their receipt; and

Such remedies may be exercised from time to time separately or in combination. Nothing in this Indenture shall curtail or limit the remedies of the Trustee as permitted by any law. or statute to a mortgagee or creditor, all such remedies being in addition to and not in substitution for any other rights or remedies of the Trustee howsoever created.

The Trustee shall not be liable by reason of any entry into or taking possession of any of the Collateral hereby charged or intended so to be or any part thereof to account as mortgagee in possession or for anything except actual receipts or be liable for any loss on realization, or army act or omission for which a secured party in possession might be liable. The Trustee shall not, by virtue of these presents, be deemed to be a mortgagee in possession of the Collateral. The Trustee shall not be liable or accountable for any failure to exercise is remedies; take possession of, seize,

collect, realize, sell, lease or otherwise dispose of or obtain payment for the Collateral and shall not be bound to institute proceedings for such purposes or for the purpose of preserving any rights, remedies or powers of the Trustee, the Issuer or any other person in respect of same. The Issuer hereby releases and discharges the Trustee and the Receiver from every claim of every nature, whether. sounding in damages or not, which may arise or be caused to the Issuer or any person claiming through or under the Issuer by reason or as a result of anything done or omitted to be done, as the case may be, by the Trustee or any successor or assign claiming through or under the Trustee or the Receiver under the provisions of this Debenture, unless such claim be the result of gross negligence, wilfull misconduct or fraud.

The Master Indenture, as supplemented by this Seventh Supplemental Indenture, shall be and continue in full force and effect and is hereby confirmed.

The Issuer is a limited partnership formed under the Partnership Act (Alberta}, a limited partner of which is only liable for any of its liabilities or any of its losses to the extent of the amount that such limited partner has contributed or agreed to contribute to its capital and such limited partner's pro rata share of any undistributed income.

This Trustee accepts the trusts in this Seventh Supplemental Indenture declared and provided and agrees to perform the same upon the terms and conditions contained herein.

The Issuer shall, from time to time, take such action and execute and deliver to the Trustee such agreements, conveyances, deeds and other documents and instruments which are necessary or advisable for giving the Trustee a valid Charge, ranking as contemplated in the Master Indenture and this Indenture, upon any Collateral to secure the payment and the performance of all Obligations from time to time.

The Seventh Supplemental Indenture may be simultaneously executed in several counterparts, each of which when so executed shall be deemed to be an original and such counterparts together shall constitute one and the same instrument.

Fro the purposes of convenience, this Seventh Supplemental Indenture may be referred to as bearing a formal date of April 28, 2003 irrespective of the actual date of execution hereof.

This Seventh Supplemental Indenture shall be governed by and construed in accordance with the laws of the Province of Alberta and the laws of Canada applicable therein.

IN WITNESS OF WHICH the parties hereto have executed these presents under their respective corporate seals and the hands of their proper officers in that behalf.