<PAGE>   1

                                                                  EXHIBIT 4.4(a)






                      BONNEVILLE PACIFIC SECURITY AGREEMENT

                          DATED AS OF FEBRUARY 22, 2001

                                     MADE BY

                         BONNEVILLE PACIFIC CORPORATION

                                   AS GRANTOR,

                                       TO

                              THE BANK OF NEW YORK,

                                   AS TRUSTEE




<PAGE>   2



                      BONNEVILLE PACIFIC SECURITY AGREEMENT

         This SECURITY AGREEMENT dated as of February 22, 2001, made by
BONNEVILLE PACIFIC CORPORATION, a Delaware corporation (the "GRANTOR"), to THE
BANK OF NEW YORK, a New York banking corporation, in its capacity as trustee
(the "TRUSTEE") for the holders from time to time (the "HOLDERS") of the Notes
(as defined in the Indenture referred to below), issued by East Coast Power
L.L.C., a Delaware limited liability company (the "COMPANY") under the Indenture
referred to below.

                             PRELIMINARY STATEMENTS

         (1) The Company and the Trustee have entered into an indenture dated as
of April 20, 1999 (as amended, restated, supplemented or otherwise modified from
time to time, the "INDENTURE"), pursuant to which the Company issued Notes in an
aggregate principal amount of $850,000,000. Unless otherwise defined in this
Agreement, capitalized terms used in this Agreement have the meanings specified
in the Indenture.

         (2) On even date herewith, Grantor was admitted as a member of the
Company and as a condition precedent to such admission by Grantor, Trustee has
required that Grantor's membership interest in the Company be pledged to Trustee
as security under the Indenture.

         (3) Grantor has agreed to grant the security interest and make the
pledge and assignment contemplated by this Agreement.

         NOW, THEREFORE, in consideration of the premises, the Grantor hereby
agrees with the Trustee, for the benefit of the Trustee and for the ratable
benefit of the Holders of the Notes, as follows:

         SECTION 1. CERTAIN DEFINED TERMS. Unless otherwise defined in this
Section 1, (a) capitalized terms used in this Agreement have the meanings
specified in the Indenture, and (b) terms used in Article 8 or 9 of the Uniform
Commercial Code from time to time in effect in the State of New York (the
"NYUCC") are used herein as therein defined. As used in this Agreement, the
following terms shall have the following meanings (such meanings to be equally
applicable to both the singular and the plural forms of the terms defined):

         "COLLATERAL" has the meaning specified in Section 2.

         "NYUCC" has the meaning specified above in this Section 1.

         "PLEDGED INTERESTS" has the meaning specified in Section 2(a).

         "SECURED OBLIGATIONS" has the meaning specified in Section 3.

         "SECURITY COLLATERAL" has the meaning specified in Section 2(a).



                                       2
<PAGE>   3



         SECTION 2. GRANT OF SECURITY. The Grantor hereby pledges and assigns to
the Trustee, for its benefit and the ratable benefit of the Holders of the
Notes, and hereby grants to the Trustee, for its benefit and for the ratable
benefit of the Holders of the Notes, a continuing security interest in and to
all of the Grantor's right, title and interest in and to, the following (whether
consisting of investment securities, book-entry securities or other securities,
security entitlements, financial assets or other investment property, accounts,
general intangibles, instruments or documents, securities accounts, deposit
accounts or other bank, trust or cash collateral accounts, or other property,
assets or rights), whether now owned or hereafter acquired, wherever located and
whether now or hereafter existing (collectively, the "COLLATERAL"):

                  (a) all of the membership interests in the Company described
         on Schedule I hereto whether or not evidenced by certificates
         (collectively, the "PLEDGED INTERESTS"), and the certificates, if any,
         representing such interests, any security therefor and all dividends,
         distributions, profits, bonuses, premiums, income, cash, instruments
         and other property and assets from time to time received, receivable or
         otherwise distributed in respect of or in exchange for any or all of
         such membership interests (all such Collateral being, the "SECURITY
         COLLATERAL"); and

                  (b) all proceeds (including cash proceeds) of any and all of
         the foregoing Collateral (including, without limitation, proceeds that
         constitute property of the types described in clause (a) of this
         Section 2) and, to the extent not otherwise included, all (i) payments
         under insurance (whether or not the Trustee is the loss payee thereof),
         or any indemnity, warranty or guaranty, payable by reason of loss or
         damage to or otherwise with respect to any of the foregoing Collateral
         and (ii) payments and distributions made with respect to the foregoing
         Collateral.

         SECTION 3. SECURITY FOR OBLIGATIONS. This Agreement secures the payment
of all obligations, now or hereafter existing, of the Company under the
Indenture and the Notes and of the Grantor under this Agreement (including,
without limitation, any extensions, modifications, substitutions, amendments and
renewals thereof), in each case whether direct or indirect, absolute or
contingent, and whether for principal, interest, fees, indemnification payments,
contract causes of action, costs, expenses or otherwise (all such obligations
being the "SECURED OBLIGATIONS"). Without limiting the generality of the
foregoing, this Agreement secures, to the fullest extent permitted by applicable
law, the payment of all amounts that constitute part of the Secured Obligations
and would be owed by the Company to the Trustee or the Holders under the
Indenture, the Notes or the Security Documents but for the fact that they are
unenforceable or not allowable due to the existence of a bankruptcy,
reorganization or similar proceeding involving the Company.

         SECTION 4. DELIVERY OF COLLATERAL.

                  (a) The Grantor shall ensure that all certificates or
         instruments representing or evidencing Security Collateral, if any, are
         delivered to and be held by or on behalf of the Trustee pursuant hereto
         and are in suitable form for transfer by delivery or shall be
         accompanied by duly executed instruments of transfer or assignment in
         blank, all in form and substance reasonably satisfactory to the
         Trustee. The Trustee shall have the right, at



                                       3
<PAGE>   4


         any time and without notice to the Grantor, to transfer to or register
         in the name of the Trustee or any of its nominees any or all of the
         Security Collateral, subject only to the revocable rights specified in
         Section 11(b). In addition, the Trustee shall have the right at any
         time and from time to time to exchange certificates or instruments
         representing or evidencing Security Collateral held by them for
         certificates or instruments of smaller or larger denominations.

                  (b) Concurrently with the execution and delivery of this
         Agreement, the Grantor shall cause to be filed proper financing
         statements in all jurisdictions necessary or prudent to perfect and
         protect the liens and security interests created hereunder, covering
         the Collateral described herein.

         SECTION 5. REPRESENTATIONS AND WARRANTIES. The Grantor represents and
warrants as of the date of this Agreement as follows:

                  (a) The Grantor is a corporation duly organized, validly
         existing and in good standing under the laws of the State of Delaware.
         The Grantor has all corporate power and authority and all governmental
         licenses, authorizations, consents and approvals required in each case
         to carry on its business as now conducted, except to the extent that
         the failure to have such power, authority, licenses, authorizations,
         consents and approvals could not reasonably be expected to have a
         material adverse effect on the Grantor's ability to perform any of its
         obligations hereunder or a material adverse effect on the business,
         operations, assets or financial condition of the Grantor and its
         Subsidiaries taken as a whole (a "GRANTOR MATERIAL ADVERSE EFFECT").

                  (b) The execution, delivery and performance by the Grantor of
         this Agreement are within the Grantor's corporate powers, have been
         duly authorized by all necessary action of the Grantor, require, in
         respect of the Grantor, no action by or in respect of, or filing with,
         any governmental body, agency or official (other than the filing of
         financing statements in favor of the Trustee on or prior to the date
         hereof as may be required for the perfection of the Security Interest
         herein granted in the Collateral) and do not contravene, or constitute
         a default under, any provision of law or regulation (including
         Regulation X of the Board of Governors of the Federal Reserve System)
         applicable to the Grantor or Regulation U of the Board of Governors of
         the Federal Reserve System or the certificate of incorporation or
         bylaws of the Grantor or any judgment, injunction, order, decree or
         material agreement binding upon the Grantor or result in or require the
         creation or imposition of any Lien on any of the Collateral.

                  (c) This Agreement has been duly executed and delivered by the
         Grantor. This Agreement is the legal, valid and binding obligation of
         the Grantor, enforceable against the Grantor in accordance with its
         terms, except as the enforceability thereof may be limited by any
         applicable bankruptcy, insolvency, reorganization, moratorium or
         similar laws affecting creditors' rights generally and by general
         principles of equity.

                  (d) There is no pending, or to the Grantor's knowledge,
         threatened action, suit or proceeding against the Grantor before any
         court or arbitrator or any governmental



                                       4
<PAGE>   5


         body, agency or official in which there is a reasonable possibility of
         an adverse decision which could reasonably be expected to have a
         Grantor Material Adverse Effect or which in any manner draws into
         question the legality, validity, binding effect or enforceability of
         this Agreement.

                  (e) The chief place of business and chief executive office of
         the Grantor are located at the address specified in Section 17. The
         Grantor has no trade names.

                  (f) The Grantor is the legal and beneficial owner of the
         Collateral which is in existence on the date hereof free and clear of
         any Lien (other than Liens not prohibited by the Indenture), except for
         the security interest created by this Agreement. No effective financing
         statement or other instrument similar in effect covering all or any
         part of the Collateral is on file in any recording office, and the
         Grantor has not entered into any security control agreement or other
         agreement similar in effect, in each case covering all or any part of
         the Collateral, except such as may have been filed in favor of the
         Trustee relating to this Agreement or the other Security Documents.

                  (g) There are no existing options, warrants, calls or
         commitments of any character whatsoever relating to any Equity
         Interests in the Company owned by the Grantor except for this Agreement
         and the limited liability company agreement of the Company. There are
         no shareholder agreements, voting trust agreements or other agreements
         or understandings to which the Grantor is a party or by which the
         Grantor may otherwise be bound that affect the voting or other rights
         of a holder of any Equity Interest in the Company (including, without
         limitation, the ability to transfer any such Equity Interest), except
         for this Agreement and the limited liability company agreement of the
         Company.

                  (h) This Agreement, the pledge of the Collateral pursuant
         hereto and the pledge, assignment and delivery to the Trustee of the
         certificates representing the Security Collateral pursuant hereto,
         together with stock or other transfer powers duly executed in blank,
         create a valid and perfected first priority security interest in the
         Collateral, securing the payment of the Secured Obligations, and all
         filings and other actions necessary to perfect and protect such
         security interest have been duly taken.

                  (i) No consent of any other Person and no authorization,
         approval or other action by, and no notice to or filing with, any
         governmental authority or regulatory body or other third party is
         required either (i) for the grant by the Grantor of the assignment and
         security interest granted hereby, for the pledge by the Grantor of any
         of the Collateral pursuant hereto or for the execution, delivery or
         performance of this Agreement by the Grantor, (ii) for the perfection
         or continuation of perfection of the pledge, assignment and security
         interest created hereby (including the priority of such pledge,
         assignment or security interest), except for the filing of financing
         and continuation statements under the Uniform Commercial Code, which
         financing statements have been duly filed, (iii) for the exercise by
         the Trustee of its voting or other rights provided for in this
         Agreement or the remedies in respect of the Collateral pursuant to this
         Agreement, except as may be required in connection with the disposition
         of any portion of the Security Collateral by



                                       5
<PAGE>   6


         laws affecting the offering and sale of securities generally or (iv)
         consents, authorizations, approvals or other actions or filings that
         have been made or obtained on or prior to the date hereof.

         SECTION 6. FURTHER ASSURANCES; PLACE OF PERFECTION.

                  (a) The Grantor agrees that from time to time, at its sole
         expense, the Grantor will promptly execute and deliver all further
         instruments and documents, and take all further action, that may be
         necessary or prudent, or that the Trustee may reasonably request, in
         order to perfect and protect any pledge, assignment or security
         interest granted or purported to be granted hereunder (including,
         without limitation, the priority thereof) or to enable the Trustee to
         exercise and enforce its rights and remedies hereunder. Without
         limiting the generality of the foregoing, the Grantor will:

                           (i) if any Collateral shall be evidenced by a
                  certificate, promissory note or other instrument or by chattel
                  paper, deliver and pledge to the Trustee hereunder such
                  certificate, note or other instrument or such chattel paper
                  duly endorsed and accompanied by duly executed instruments of
                  transfer or assignment, all in form and substance reasonably
                  satisfactory to the Trustee; and

                           (ii) execute and file such financing statements,
                  continuation statements or other similar documents, or
                  amendments thereto, and such other instruments or notices, as
                  may be necessary or as the Trustee may deem reasonably prudent
                  and may request, in order to perfect and preserve the pledge,
                  assignment and security interest granted or purported to be
                  granted under this Agreement.

                  (b) The Grantor hereby authorizes the Trustee to cause the
         filing of one or more financing statements, continuation statements or
         other similar documents, and amendments thereto, relating to all or any
         part of the Collateral without the signature of the Grantor where
         permitted by applicable law. A photocopy or other reproduction of this
         Agreement or any financing statement or other similar document covering
         the Collateral or any part thereof shall be sufficient as a financing
         statement or other similar document where permitted by applicable law.

                  (c) The Grantor shall furnish to the Trustee from time to time
         statements and schedules further identifying and describing the
         Collateral and such other reports in connection with the Collateral as
         the Trustee may reasonably request, all in reasonable detail.

         SECTION 7. COVENANT TO GIVE FURTHER SECURITY. The Grantor hereby agrees
that, if, and at such time as, it acquires title to, or any other ownership
interest in, any additional Equity Interests in any issuer of the Pledged
Interests, it will, at its sole expense:

                  (a) as promptly as practicable and in any event within five
         (5) days after such acquisition, notify the Trustee of its acquisition
         of title thereto or such other ownership interest therein; and


                                       6
<PAGE>   7


                  (b) as promptly as practicable and in any event within 30 days
         after such acquisition, (i) duly execute and deliver such mortgages,
         pledges, assignments and/or other security agreements as are necessary
         to create a valid lien thereon and security interest therein in favor
         of the Trustee, for its benefit and the benefit of the Holders of the
         Notes, in each case in form and substance satisfactory to the Trustee,
         and (ii) make all filings and take all other actions that are necessary
         or that the Trustee may deem reasonably prudent and may request to
         perfect and protect a valid and perfected first priority lien thereon
         and security interest therein in favor of the Trustee, for its benefit
         and the benefit of the Holders of the Notes.

         SECTION 8. TRUSTEE APPOINTED ATTORNEY-IN-FACT. In addition to all of
the powers granted to the Trustee pursuant to the Indenture, the Grantor hereby
irrevocably appoints the Trustee its attorney-in-fact (which appointment is
coupled with an interest and is irrevocable), with full authority in the place
and stead of the Grantor and in the name of the Grantor or otherwise and with
full power of substitution, from time to time upon the occurrence and during the
continuation of an Event of Default, to take any action and to execute any
instrument to accomplish the purposes of this Agreement (it being understood
that the Trustee will not be required to act unless otherwise set forth herein
or in the Indenture), including, without limitation:

                  (a) upon the occurrence and during the continuation of an
         Event of Default, to ask for, demand, collect, sue for, recover,
         compromise, receive, and give acquittance and receipts for, moneys due
         and to become due under or in respect of any of the Collateral;

                  (b) to receive, endorse and collect any drafts, instruments or
         other documents or any chattel paper in connection with this Agreement
         (including, without limitation, all instruments representing or
         evidencing any interest payment or other distribution in respect of the
         Security Collateral or any part thereof) and to give full discharge for
         the same;

                  (c) to sell, transfer, assign or otherwise deal with the
         Collateral or any part thereof under, and in accordance with, the terms
         of the Indenture or Section 14 in the same manner and to the same
         extent as if the Trustee was the absolute owner thereof; and

                  (d) upon the occurrence and during the continuation of any
         Event of Default, to file any claims or take any action or institute
         any proceedings that may be necessary or that the Trustee may deem
         desirable for the collection of any of the Collateral or otherwise to
         enforce the rights of the Trustee with respect to any of the
         Collateral.

         SECTION 9. TRUSTEE MAY PERFORM. If the Grantor fails to make any
payment required to be made by it, or to perform any other act or agreement
required to be performed by it, in each case under this Agreement, the Trustee,
without waiving or releasing any obligation or default, may (but shall not be
obligated to) make such payment or perform such other act, or cause the payment
or performance thereof, for the account and at the sole expense of the Grantor.
All amounts so paid by the Trustee and all costs and expenses so incurred shall
constitute obligations



                                       7
<PAGE>   8



of the Grantor secured hereunder and shall be payable under Section 15(b). The
Trustee shall not be liable for any damages resulting from any such payment or
performance.

         SECTION 10. NO ASSUMPTION OF DUTIES; REASONABLE CARE. The rights and
powers conferred on the Trustee hereunder are solely to preserve and protect the
security interest of the Trustee and the Holders of the Notes in and to the
Collateral granted hereby and shall not be interpreted to, and shall not impose
any duties on the Trustee in connection therewith other than those expressly
provided herein or imposed under applicable law. Except as provided by
applicable law or by the Indenture, the Trustee shall be deemed to have
exercised reasonable care in the custody and preservation of the Collateral in
its possession if the Collateral is accorded treatment substantially equal to
that which the Trustee accords similar property held by the Trustee for its own
account, it being understood that the Trustee in its capacity as such shall not
have any responsibility for (a) ascertaining or taking action with respect to
calls, conversions, exchanges, maturities or other matters relative to any
Collateral, whether or not the Trustee has or is deemed to have knowledge of
such matters or (b) taking any necessary steps to preserve rights against any
parties with respect to any Collateral. The Trustee shall be entitled to all the
rights, benefits, privileges and immunities accorded to it under the Indenture.

         SECTION 11. VOTING RIGHTS; DIVIDENDS; ETC.

                  (a) So long as no Event of Default shall have occurred and be
         continuing:

                           (i) The Grantor shall be entitled to exercise or
                  refrain from exercising any and all voting and other
                  consensual rights pertaining to the Security Collateral
                  pledged and assigned by it hereunder, or any part thereof, for
                  any purpose not inconsistent with the terms of this Agreement,
                  the Indenture and the Notes;

                           (ii) The Grantor shall be entitled to receive,
                  retain, and distribute any and all dividends, interest and
                  other distributions paid or distributed in respect of the
                  Security Collateral if and to the extent that the payment
                  thereof is not otherwise prohibited by the terms of the
                  Indenture or the Notes;

                           (iii) The Trustee shall execute and deliver (or cause
                  to be executed and delivered) to the Grantor all such proxies
                  and other instruments as the Grantor may reasonably request
                  for the purpose of enabling the Grantor to exercise the voting
                  and other rights that it is entitled to exercise pursuant to
                  paragraph (i) above and to receive the dividends or interest
                  payments that it is authorized to receive, retain, and
                  distribute pursuant to paragraph (ii) above.

                  (b) Upon the occurrence and during the continuance of an Event
         of Default:

                           (i) All rights of the Grantor (A) to exercise or
                  refrain from exercising the voting and other consensual rights
                  that it would otherwise be entitled to exercise pursuant to
                  Section 11(a)(i) shall, upon notice to the Grantor by the
                  Trustee acting at the direction of the Holders of a majority
                  interest of Outstanding Notes, cease and (B) to receive, the
                  dividends, interest payments, and other



                                       8
<PAGE>   9


                  distributions that it would otherwise be authorized to
                  receive, retain, and distribute pursuant to Section 11(a)(ii)
                  shall automatically cease, and all such rights shall thereupon
                  become vested in the Trustee, which shall thereupon have the
                  sole right to exercise or refrain from exercising such voting
                  and other consensual rights and to receive and hold as
                  Collateral such dividends, interest payments and other
                  distributions as the Holders of a majority in interest of
                  Outstanding Notes shall direct.

                           (ii) All dividends, interest payments, and other
                  distributions that are received by the Grantor contrary to the
                  provisions of paragraph (i) of this Section 11(b) shall be
                  received in trust for the benefit of the Trustee, shall be
                  segregated from other funds of the Grantor and shall be
                  forthwith paid over to the Trustee as Collateral in the same
                  form as so received (with any necessary indorsement).

         SECTION 12. TRANSFERS AND OTHER LIENS; ADDITIONAL EQUITY INTERESTS.

                  (a) The Grantor agrees that it will not (i) sell, assign or
         otherwise dispose of, or grant any option with respect to, any of the
         Collateral of the Grantor if such sale, assignment, disposition or
         grant of option would cause or result in a Default or an Event of
         Default or (ii) create or suffer to exist any Lien on any of the
         Collateral except for Liens created hereunder.

                  (b) The Grantor agrees that it shall cause the Company not to
         issue any Equity Interests in addition to or in substitution for the
         Pledged Interests, unless immediately upon such issuance, such Equity
         Interests is pledged to the Trustee for the benefit of the Holders.

                  (c) Any sale, assignment or other disposition of any of the
         Collateral shall be subject to the Lien created hereunder in favor of
         the Trustee (on its behalf and on behalf of the Holders of the Notes)
         continuing in such Collateral.

         SECTION 13. SECURITY INTEREST ABSOLUTE. The obligations of the Grantor
under this Agreement are independent of the Secured Obligations, and a separate
action or actions may be brought and prosecuted against the Grantor to enforce
this Agreement, irrespective of whether any action is brought against the
Company or whether the Company is joined in any such action or actions. All
rights of the Trustee and the pledge, assignment and security interest
hereunder, and all obligations of the Grantor hereunder, shall be irrevocable,
absolute and unconditional, irrespective of, and the Grantor hereby irrevocably
waives (to the maximum extent permitted by applicable law) any defenses it may
now have or may hereafter acquire in any way relating to, any or all of the
following:

                  (a) any lack of validity or enforceability of the Indenture,
         the Notes, any Security Document or any other agreement or instrument
         relating thereto;


                                       9
<PAGE>   10


                  (b) any change in the time, manner or place of payment of, or
         in any other term of, all or any of the Secured Obligations or any
         other obligations under the Indenture, the Notes or any Security
         Document, or any other amendment or waiver of or any consent to any
         departure from the Indenture, the Notes or any Security Document,
         including, without limitation, any increase in the Secured Obligations
         resulting from the extension of additional credit to the Company, any
         of its Subsidiaries or otherwise;

                  (c) any taking, exchange, release or non-perfection of any
         other collateral, or any taking, release or amendment or waiver of or
         consent to departure from any guaranty, for all or any of the Secured
         Obligations;

                  (d) any manner of application of Collateral, or proceeds
         thereof, to all or any of the Secured Obligations, or any manner of
         sale or other disposition of any Collateral for all or any of the
         Secured Obligations or any other obligations of the Company under or in
         respect of the Indenture, the Notes, and the Security Documents or any
         other assets of the Company or any of its Subsidiaries;

                  (e) any change, restructuring or termination of the corporate,
         partnership or other structure or existence of the Company or any of
         its Subsidiaries; and

                  (f) any other circumstance (including without limitation any
         statute of limitations) that might otherwise constitute a defense
         available to, or a discharge of, the Grantor or a third party grantor
         of a security interest other than the payment in full of the Secured
         Obligations.

         SECTION 14. REMEDIES. If an Event of Default shall have occurred and be
continuing:

                  (a) The Trustee or the majority of the Holders of the Notes
         may, or in the event of an acceleration under Section 502 of the
         Indenture then the Trustee shall, exercise in respect of the
         Collateral, in addition to other rights and remedies provided for
         herein or in the Indenture or otherwise available to it, all the rights
         and remedies of a secured party upon default under the NYUCC (whether
         or not the NYUCC applies to the affected Collateral) and also may (i)
         require the Grantor to, and the Grantor hereby agrees that it will at
         its expense and upon request of the Trustee forthwith, assemble all or
         part of the Collateral as directed by the Trustee and make it available
         to the Trustee at a place to be designated by the Trustee that is
         reasonably convenient to both parties and (ii) without notice except as
         specified below, sell the Collateral or any part thereof in one or more
         parcels at public or private sale, at any of the Trustee's offices or
         elsewhere, for cash, on credit or for future delivery, and upon such
         other terms as commercially reasonable. The Grantor agrees that, to the
         extent notice of sale shall be required by law, at least ten days'
         notice to the Grantor of the time and place of any public sale or the
         time after which any private sale is to be made shall constitute
         reasonable notification. The Trustee shall not be obligated to make any
         sale of Collateral regardless of notice of sale having been given. The
         Trustee may adjourn any public or private sale from time to time by
         announcement at the time and place fixed therefor, and such sale may,
         without further notice, be made at the time and place to which it was
         so adjourned.



                                       10
<PAGE>   11


                  (b) All cash proceeds received by the Trustee in respect of
         any sale of, collection from, or other realization upon all or any part
         of the Collateral be held by the Trustee as collateral for, and/or then
         or at any time thereafter applied (after payment of any amounts payable
         to the Trustee pursuant to Section 15(b)) in whole or in part by the
         Trustee for the ratable benefit of the Holders of the Notes against,
         all or any part of the Secured Obligations in such order as the Trustee
         shall elect. Any surplus of such cash or cash proceeds held by the
         Trustee and remaining after payment in full of all the Secured
         Obligations shall be paid over to the Grantor or to whomsoever else may
         be lawfully entitled to receive such surplus.

                  (c) Notwithstanding the foregoing, the Grantor and the Trustee
         recognize that any disposition of Collateral must be made in accordance
         with any applicable federal or state securities laws. The Grantor
         recognizes that the Trustee may deem it impracticable to effect a
         public sale of all or any part of the Collateral subject to such
         securities laws and that the Trustee may, therefore, determine to make
         one or more private sales of any such Collateral to a restricted group
         of purchasers who will be obligated to agree, among other things, to
         acquire such Collateral for their own account, for investment and not
         with a view to the distribution or resale thereof. The Grantor
         acknowledges that any such private sale may be at prices and on terms
         less favorable than the prices and other terms which might have been
         obtained at a public sale and, notwithstanding the foregoing, agrees
         that such private sale shall be deemed to have been made in a
         commercially reasonable manner and that the Trustee shall have no
         obligation to delay sale of any such securities for the period of time
         necessary to permit the Grantor to register such Collateral for public
         sale under the Securities Act of 1933, as amended.

         SECTION 15. INDEMNITY AND EXPENSES.

                  (a) The Grantor agrees to indemnify, defend and save and hold
         harmless the Trustee and each of its officers, directors, employees,
         agents and advisors (each, an "Indemnified Party") from and against,
         and shall pay on demand, any and all claims, damages, losses,
         liabilities and expenses (including, without limitation, reasonable
         fees and expenses of counsel) that may be incurred by or asserted or
         awarded against any Indemnified Party, in each case arising out of or
         in connection with or resulting from the Trustee's performance as
         Trustee under this Agreement (including, without limitation,
         enforcement of this Agreement), except any such claim, damage, loss,
         liability or expense as may be attributable to its negligence or
         willful misconduct.

                  (b) The Grantor will upon demand pay to the Trustee (i) the
         amount of any and all reasonable out-of-pocket costs and expenses of
         the Trustee, including the reasonable fees, expenses, and disbursements
         of counsel to the Trustee and of any experts and agents, that the
         Trustee may incur in connection with (A) the custody, preservation, use
         or operation of, or the sale of, collection from or other realization
         upon, any of the Collateral or (B) the failure by the Grantor to
         perform or observe any of the provisions hereof; and (ii) all costs and
         expenses of the Trustee and each of the Holders of the Notes in
         connection with the exercise of any of their rights hereunder or the
         enforcement of this Agreement (including, without limitation, the
         reasonable fees and expenses of counsel for


                                       11
<PAGE>   12



         the Trustee and each of the Holders of the Notes with respect thereto),
         whether in any action, suit or litigation, any bankruptcy, insolvency
         or other similar proceeding affecting creditors' rights generally or in
         any negotiated settlement or workout, except in the case of clauses (i)
         and (ii), any such cost, expense, or disbursement as may be
         attributable to the Trustee's negligence or willful misconduct.

                  (c) Without prejudice to the survival of any other agreement
         of the Grantor hereunder, the agreements and obligations of the Grantor
         contained in this Section 16 shall survive the termination of this
         Agreement and the resignation or removal of the Trustee.

         SECTION 16. AMENDMENTS, WAIVERS AND CONSENTS.

                  (a) Any amendment or waiver of any provision of this Agreement
         and any consent to any departure by the Grantor from any provision of
         this Agreement shall be effective only if in writing, signed by the
         Trustee and made or duly given in compliance with all of the terms and
         provisions of the Indenture, and then such waiver or consent shall be
         effective only in the specific instance and for the specific purpose
         for which given. Neither the Trustee nor any Holder of Notes shall be
         deemed, by any act, delay, indulgence, omission or otherwise, to have
         waived any right or remedy hereunder or to have acquiesced in any
         Default or Event of Default or in any breach of any of the terms and
         conditions hereof. Failure of the Trustee or any Holder of Notes to
         exercise, or delay in exercising, any right, power or privilege
         hereunder shall not preclude any other or further exercise thereof or
         the exercise of any other right, power or privilege. A waiver by the
         Trustee or any Holder of Notes of any right or remedy hereunder on any
         one occasion shall not be construed as a bar to any right or remedy
         that the Trustee or such Holder of Notes would otherwise have on any
         future occasion. The rights and remedies herein provided are
         cumulative, may be exercised singly or concurrently and are not
         exclusive of any rights or remedies provided by law.

                  (b) Without the consent of any Holders of the Notes and the
         Grantors, the Trustee may amend or waive any provision of this
         Agreement or consent to any departure by any Grantor from any provision
         hereof, for any of the following purposes:

                           (i) to evidence the succession of another Person to
                  the Company, or any other Grantor, and the assumption by any
                  such successor of the obligations of the Company or such other
                  Grantor contained herein;

                           (ii) to evidence and provide for the appointment of a
                  successor Trustee;

                           (iii) to cure any ambiguity, to correct or supplement
                  any provision in this Agreement that may defective or
                  inconsistent with any other provision of this Agreement or the
                  Indenture, or to make any other provisions with respect to
                  matters or questions arising under this Agreement with shall
                  not be inconsistent with the provisions of this Agreement or
                  the Indenture; provided that, in each



                                       12
<PAGE>   13


                  case, such actions pursuant to this clause shall not
                  materially adversely affect the interests of the Holders; or

                           (iv) to mortgage, pledge, hypothecate or grant of
                  security interest in additional collateral in favor of the
                  Trustee for the benefit of the Holders.

         SECTION 17. NOTICES; ETC. All notices and other communications provided
for hereunder shall be in writing (including telecopier, telegraphic or cable
communication) and, mailed, telecopied, cabled or delivered:

                  (a)      if to the Grantor, at its address at:

                           Bonneville Pacific Corporation
                           c/o El Paso Merchant Energy Holding Company
                           1001 Louisiana Street
                           Houston, Texas 77002
                           Telecopy: (713) 420-3220
                           Attn: John Harrison

                           with copy to:

                           El Paso Corporation
                           1001 Louisiana Street
                           Houston, Texas 77002
                           Telecopy: (713) 420-2813
                           Attn: Andrew Kidd

                  (b)      if to the Trustee, at its Corporate Trust Office
                           referred to in the Indenture;

or, as to any such party, at such other address as shall be designated by such
party in a written notice to each other party complying as to delivery with the
terms of this Section. All such notices and communications shall, when mailed,
telecopied, telegraphed or telexed, be effective when deposited in the mails,
telecopied, or confirmed by telex answerback, respectively, except that notices
and communications to the Trustee shall not be effective until received by the
Trustee. Delivery by telecopier of an executed counterpart of any amendment or
waiver of any provision of this Agreement to be executed and delivered hereunder
shall be effective as delivery of a manually executed counterpart thereof.

         SECTION 18. CONTINUING SECURITY INTEREST. Subject to any collateral
released under Section 16, this Agreement shall create a continuing security
interest in and to the Collateral and shall (a) remain in full force and effect
until the payment in full in cash of the Secured Obligations, (b) be binding
upon the Grantor and its successors and permitted assigns and (c) inure,
together with the rights and remedies of the Trustee hereunder, to the benefit
of, and be enforceable by, the Trustee, the Holders of the Notes and their
respective successors, transferees and assigns. Without limiting the generality
of the foregoing clause (c), the Trustee may assign or otherwise transfer all or
any portion of its rights and obligations under the Indenture and the


                                       13
<PAGE>   14


Notes to any other Person, and such other Person shall thereupon become vested
with all the benefits in respect thereof granted to the Trustee, as the case may
be, herein or otherwise, in each case as and to the extent provided in Section
610 of the Indenture.

         SECTION 19. WAIVERS AND ACKNOWLEDGMENTS.

                  (a) The Grantor hereby waives promptness, diligence, notice of
         acceptance and any other notice with respect to any of the Secured
         Obligations and this Agreement and any requirement that the Trustee or
         any Holder of a Note protect, secure, perfect or insure any Lien or any
         property subject thereto or exhaust any right or take any action
         against the Company or any other Person or any Collateral.

                  (b) The Grantor hereby waives any right to revoke this
         Agreement, and acknowledges that this Agreement is continuing in nature
         and applies to all Secured Obligations, whether existing now or in the
         future.

                  (c) The Grantor acknowledges that it will receive substantial
         direct and indirect benefits from the financing arrangements
         contemplated by the Indenture, the Notes and the Security Documents and
         that the waivers set forth in this Section 19 are knowingly made in
         contemplation of such benefits.

         SECTION 20. SUBROGATION. The Grantor will not exercise any rights that
it may now or hereafter acquire against the Company or any of its Subsidiaries
that arise from the existence, payment, performance or enforcement of the
Grantor's obligations under this Agreement, including, without limitation, any
right of subrogation, reimbursement, exoneration, contribution or
indemnification and any right to participate in any claim or remedy of the
Trustee or any Holders of the Notes against the Company or of its Subsidiaries
or any Collateral, whether or not such claim, remedy or right arises in equity
or under contract, statute or common law, including, without limitation, the
right to take or receive from the Company or any of its Subsidiaries, directly
or indirectly, in cash or other property or by set-off or in any other manner,
payment or security on account of such claim, remedy or right, unless and until
all of the Secured Obligations and all other amounts payable under this
Agreement shall have been paid in full in cash (except that the Grantor may
exercise any such claim, right or remedy solely against, and the Grantor may
take and receive any such amount solely from, amounts permitted to be
distributed or paid on account of Subordinated Indebtedness in accordance with
and subject to the restrictions set forth in Section 1012 of the Indenture). If
any amount shall be paid to the Grantor in violation of the preceding sentence
at any time prior to the later of the payment in full in cash of the Secured
Obligations and all other amounts payable under this Agreement, such amount
shall be held in trust for the benefit of the Trustee and the other Holders of
the Notes and shall forthwith be paid to the Trustee to be credited and applied
to the Secured Obligations and all other amounts payable under this Agreement,
whether matured or unmatured, in accordance with the terms of the Indenture, or
to be held as Collateral for any Secured Obligations or other amounts payable
under this Agreement thereafter arising.

         SECTION 21. RELEASE AND TERMINATION. Upon the payment in full in cash
of the Secured Obligations, the pledge, assignment and security interest granted
hereby shall terminate


                                       14
<PAGE>   15


and all rights to the Collateral shall revert to the Grantor. Upon any such
termination, the Trustee will, at the Grantor's expense, execute and deliver to
the Grantor such documents as the Grantor shall reasonably request to evidence
such termination.

         SECTION 22. AUTHORITY OF THE TRUSTEE.

                  (a) The Trustee shall have and be entitled to exercise all
         powers hereunder that are specifically granted to the Trustee by the
         terms hereof, together with such powers as are reasonably incident
         thereto. The Trustee may perform any of its duties hereunder or in
         connection with the Collateral by or through agents or employees and
         shall be entitled to retain counsel and to act in reliance upon the
         advice of counsel concerning all such matters. Except as otherwise
         expressly provided in this Agreement or the Indenture, neither the
         Trustee nor any director, officer, employee, attorney or agent of the
         Trustee shall be liable to the Grantor for any action taken or omitted
         to be taken by the Trustee, in its capacity as Trustee, hereunder,
         except for its own negligence or willful misconduct, and the Trustee
         shall not be responsible for the validity, effectiveness or sufficiency
         hereof or of any document or security furnished pursuant hereto. The
         Trustee and its directors, officers, employees, attorneys and agents
         shall be entitled to rely on any communication, instrument or document
         believed by it or them to be genuine and correct and to have been
         signed or sent by the proper person or persons.

                  (b) The Grantor acknowledges that the rights and
         responsibilities of the Trustee under this Agreement with respect to
         any action taken by the Trustee or the exercise or non-exercise by the
         Trustee of any option, right, request, judgment or other right or
         remedy provided for herein or resulting or arising out of this
         Agreement shall, as between the Trustee and the Holders of the Notes,
         be governed by the Indenture and by such other agreements with respect
         thereto as may exist from time to time among them, but, as between the
         Trustee and the Grantor, the Trustee shall be conclusively presumed to
         be acting as agent for the Holders of the Notes with full and valid
         authority so to act or refrain from acting, and the Grantor shall not
         be obligated or entitled to make any inquiry respecting such authority.

         SECTION 23. EXECUTION IN COUNTERPARTS. This Agreement may be executed
in any number of counterparts and by different parties hereto in separate
counterparts, each of which when so executed shall be deemed to be an original
and all of which taken together shall constitute one and the same agreement.
Delivery of an executed counterpart of a signature page to this Agreement by
telecopier shall be effective as delivery of a manually executed counterpart of
this Agreement.

         SECTION 24. REINSTATEMENT. This Agreement shall continue to be
effective or be reinstated, as the case may be, if at any time any payment of
any of the Secured Obligations is rescinded or must otherwise be returned by the
Trustee, any Holder of the Notes or by any other Person upon the insolvency,
bankruptcy or reorganization of the Company or otherwise, all as though such
payment had not been made.



                                       15
<PAGE>   16


         SECTION 25. SEVERABILITY. Any provision of this Agreement which is
prohibited or unenforceable in any jurisdiction shall, as to such jurisdiction,
be ineffective to the extent of such prohibition or unenforceability without
invalidating the remaining provisions hereof, and any such prohibition or
unenforceability in any jurisdiction shall not invalidate or render
unenforceable such provision in any other jurisdiction.

         SECTION 26. GOVERNING LAW; ENTIRE AGREEMENT. This Agreement shall be
governed by, and construed in accordance with, the laws of the State of New
York. This Agreement constitutes the entire understanding among the Grantor, the
Trustee and the Holders of the Notes with respect to the subject matter hereof
and supercede any prior agreements, written or oral, with respect thereto.

                         [SIGNATURES BEGIN ON NEXT PAGE]




                                       16
<PAGE>   17




         IN WITNESS WHEREOF, the parties hereto have caused this Agreement to be
duly executed and delivered by its officer thereunto duly authorized as of the
date first above written.

                                           BONNEVILLE PACIFIC CORPORATION



                                           By: /s/ D. T. Field
                                               ---------------------------------
                                           Name: D. T. Field
                                                 -------------------------------
                                           Title: Attorney-in-Fact
                                                  ------------------------------


                                           THE BANK OF NEW YORK, AS TRUSTEE



                                           By: /s/ Marybeth Lewicki
                                               ---------------------------------
                                           Name: Marybeth Lewicki
                                                 -------------------------------
                                           Title: Vice President
                                                  ------------------------------






                                Signature Page-1

<PAGE>   18


                                   SCHEDULE I

                                EQUITY INTERESTS

<Table>
<Caption>
                                                                PERCENTAGE OF
                                                             OUTSTANDING EQUITY
   ISSUER                       TYPE OF INTEREST                   INTEREST
   ------                       ----------------             ------------------
<S>                        <C>                            <C>

East Coast Power L.L.C.    Class A Limited Liability      Class A Limited Liability
                           Company Membership             Company Membership
                           Interest                       Interest representing a .9%
                                                          Sharing Ratio
</Table>









                                   Schedule I