Exhibit 4.6













                               KEYSPAN CORPORATION

                                       AND

                            THE CHASE MANHATTAN BANK,

                                   as Trustee




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

                         FORM OF SUPPLEMENTAL INDENTURE
                         RELATING TO JUNIOR SUBORDINATED
                          DEBENTURES ISSUED TO A TRUST

                            Dated as of ______, 200_

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













                  THIS ______ SUPPLEMENTAL INDENTURE, dated as of ______, 200_,
is between KEYSPAN CORPORAITON, doing business as KeySpan Energy, a corporation
duly incorporated and existing under the laws of the State of New York and
having its principal executive office at One MetroTech Center, Brooklyn, New
York 11201 (the "Company"), and THE CHASE MANHATTAN BANK, a corporation
organized and existing under the laws of the State of New York, acting as
Trustee under the Indenture referred to below (the "Trustee").

                               W I T N E S S E T H

                  WHEREAS, the Company has duly authorized the execution and
delivery of an Indenture dated as of November 1, 2000 (the "Indenture"), as
amended and supplemented, to provide for the issuance from time to time of its
unsecured notes or other evidences of indebtedness to be issued in one or more
series (the "Securities"), as provided in the Indenture, up to such principal
amount or amounts as may from time to time be authorized in or pursuant to one
or more resolutions of the Board of Directors;

                  WHEREAS, the Company will sell on the date hereof to KeySpan
Trust __, a Delaware statutory business trust ("Trust _"), a series of
Securities entitled the "_% Junior Subordinated Deferrable Interest Debentures
due 20__" (the "__% Subordinated Debentures");

                  WHEREAS, the Company has duly authorized the execution and
delivery of this ____ Supplemental Indenture in order to provide for certain
supplements to the Indenture which shall only be applicable to the __%
Subordinated Debentures;

                  WHEREAS, all acts and things necessary to make this _____
Supplemental Indenture a valid agreement of the Company according to its terms
have been done and performed, and the execution and delivery of this ____
Supplemental Indenture have in all respects been duly authorized;

                  NOW, THEREFORE, in consideration of the premises, of the
purchase and acceptance of the Securities by the Holders thereof, and of the sum
of one dollar duly paid to it by the Trustee at the execution and delivery of
these presents, the receipt whereof is hereby acknowledged, the Company
covenants and agrees with the Trustee to supplement the Indenture, only for
purposes of the __% Subordinated Debentures, as follows:

         SECTION 1.        AMENDMENTS TO THE INDENTURE

         1.1 Amendment to Section 101 of the Indenture. Section 101 of the
Indenture is hereby amended solely with respect to the __% Subordinated
Debentures (a) by adding the following sentence as the third paragraph thereof:

     "The terms  "Common  Securities,"  "Guarantee,  "  "Preferred  Securities,"
"Property  Trustee" and "Regular  Trustees" shall have the meanings  ascribed to
them in the Trust __ Declaration."; and

(b) by  adding  the  following  new  definitions  thereto,  in  the  appropriate
alphabetical sequence:

          "__%   Subordinated   Debentures"   means  the  Company's  __%  Junior
     Subordinated Debentures due 20__.

          "Creditor" has the meaning specified in Section 1011.

          "Trust __ Declaration"  means the Amended and Restated  Declaration of
     Trust,  dated as of _____,  200_ among the Company and the  trustees  named
     therein.

          "Extension Period" has the meaning specified in Section 313.

          "Trust _" means Keyspan Trust __, a Delaware statutory business trust.

     1.2 Amendment of Article 3 of the Indenture. Article 3 is amended by adding
the following Section 313 at the end thereof:

Section  313.  Deferrals  of  Interest  Payment  Dates for the __%  Subordinated
Debentures.

                           (a) The Company shall have the right at any time, on
         one or more occasions, so long as an Event of Default has not occurred
         and is not continuing under the Indenture, to extend any interest
         payment period on the __% Subordinated Debentures for a period (an
         "Extension Period") not to exceed [ten][twenty] consecutive
         [semi-annual][quarterly] interest payment periods; provided that the
         date on which such Extension Period ends must be on an Interest Payment
         Date and must be no later than ___________ __, ____ or any date on
         which any __% Subordinated Debenture is fixed for redemption, and, as a
         consequence, the [semi-annual][quarterly] interest payment on the __%
         Subordinated Debentures would be deferred (but would continue to accrue
         with interest thereon compounded [semi-annually][quarterly] at the rate
         of interest on the __% Subordinated Debentures, except to the extent
         payment of such interest is prohibited by law) during any such
         Extension Period. On the Interest Payment Date at the end of each
         Extension Period, the Company shall pay all interest then accrued and
         unpaid (compounded [semi-annually][quarterly], at the rate of interest
         on the __% Subordinated Debentures, except to the extent payment of
         such interest is prohibited by law) to the date of payment, to the
         persons in whose name the __% Subordinated Debentures are registered on
         the Regular Record Date immediately preceding the Interest Payment Date
         at the end of such Extension Period. The Company shall give written
         notice to the Regular Trustees, the Property Trustee and the Trustee of
         its election of such Extension Period one Business Day before the
         earlier of (i) the next succeeding date on which distributions on the
         Preferred Securities of Trust __ are payable or (ii) the date Trust __
         is required to give notice of the record date or the date such
         distributions are payable to the New York Stock Exchange or other
         applicable self-regulatory organization or to holders of the Preferred
         Securities issued by Trust __, but in any event at least one Business
         Day before such record date. During any Extension Period, the Company
         may continue to extend the interest payment period by extending the
         Extension Period, on one or more occasions by giving notice as
         aforesaid; provided that such Extension Period, as extended, must end
         on an Interest Payment Date and in no event shall the aggregate
         Extension Period, as extended, exceed [ten][twenty] consecutive
         [semi-annual][quarterly] interest payment periods or extend beyond
         ___________ __, ____ or any date on which any of the __% Subordinated
         Debentures are fixed for redemption. No interest shall be due and
         payable on the __% Subordinated Debentures during an Extension Period
         except at the end thereof.

                           (b) So long as any Preferred Securities and Common
         Securities of Trust __ remain outstanding, if (i) there shall have
         occurred any Event of Default with respect to the __% Subordinated
         Debentures, (ii) the Company shall be in default with respect to its
         payment of any obligations under its Guarantee with respect to Trust __
         or (iii) the Company shall have given notice of its election of an
         Extension Period as provided herein and shall not have rescinded such
         notice, or such Extension Period or any extension thereof shall be
         continuing, then the Company shall not, and shall not permit any
         Subsidiary to (x) declare or pay any dividends or distributions on, or
         redeem, purchase, acquire or make a liquidation payment with respect
         to, any of the Company's capital stock or (y) make any payment of
         principal, interest or premium, if any, on or repay, repurchase or
         redeem any debt securities of the Company that rank on a parity with or
         junior in interest to the __% Subordinated Debentures or make any
         guarantee payments with respect to any guarantee by the Company of the
         debt securities of any Subsidiary of the Company if such guarantee
         ranks on a parity with or junior in interest to the __% Subordinated
         Debentures (other than (a) dividends or distributions in common stock
         of the Company, (b) payments under the Guarantee made by the Company in
         respect of the Preferred Securities and Common Securities of Trust __,
         (c) any declaration of a dividend in connection with any shareholders'
         rights plan, or the issuance of stock under any such plan in the
         future, or the redemption or repurchase of any such rights pursuant
         thereto, and (d) purchases of common stock related to the issuance of
         common stock or rights under any of the Company's benefit plans).

         1.3 Amendment to Section 501 of the Indenture. Section 501 is amended
by inserting the following clause (8) and renumbering the existing clause (8) as
clause (9):

                  "(8) Trust __ shall have voluntarily or involuntarily
         dissolved, wound-up its business or otherwise terminated its existence
         except in connection with (i) distribution of the Securities held by
         Trust __ to holders of its securities in liquidation of such holders'
         interests in Trust __, (ii) redemption of all of the securities issued
         by Trust __, or (iii) mergers, consolidations or amalgamations, each as
         permitted by Section 3.15 of the Trust __ Declaration."

          1.4 Amendment to Section 902 of the Indenture.  Section 902 is amended
to add the following at the end thereof:

                  "For purposes of this Section 902, if the __% Subordinated
         Debentures are held by Trust __, the consent of not less than __% of
         the aggregate liquidation amount of the securities issued by Trust __
         shall be required in order for such supplemental indenture to be
         effective."

          1.5  Amendment  to  Section  1009 of the  Indenture.  Section  1009 is
amended to add the following at the end thereof:

                  "For purposes of this Section 1009, if the __% Subordinated
         Debentures are held by Trust __, the consent of not less than a
         majority of the aggregate liquidation amount of the securities issued
         by Trust __ shall be required in order to waive a covenant."

          1.6 Amendment to Section 513 of the Indenture.  Section 513 is amended
to add the following at the end thereof:

                  "For purposes of this Section 513, if the __% Subordinated
         Debentures are held by Trust __, the consent of not less than a
         majority of the aggregate liquidation amount of the securities issued
         by Trust __ shall be required in order to waive such default."

          1.7  Amendment  to Article  Ten of the  Indenture.  Article Ten of the
Indenture  is  amended  to add the  following  covenant  at the end of such
Article:

                  "Section 1011.  Trust Covenants.

                  The Company shall, for so long as Trust __ is in existence:
         (i) maintain directly or indirectly 100% ownership of the common
         securities of Trust __, (ii) cause Trust __ to remain a statutory
         business trust and not to be voluntarily dissolved, wound-up,
         liquidated or terminated, except as provided for in the Trust __
         Declaration, (iii) use its commercially reasonable efforts to assure
         that Trust __ will not be an "investment company" for purposes of the
         Investment Company Act of 1940, (iv) take no action that would be
         reasonably likely to cause Trust __ to be classified as an association
         or as a publicly traded partnership taxable as a corporation for United
         States federal income tax purposes, and (v) agree to pay all debts and
         obligations (other than with respect to the securities issued by Trust
         __) and all costs and expenses of Trust __ (including, but not limited
         to, all costs and expenses relating to the organization of Trust __,
         the fees and expenses of the trustees and all costs and expenses
         relating to the operation of Trust __) and to pay any and all taxes,
         duties, assessments or governmental charges of whatever nature (other
         than withholding taxes) imposed on Trust __ by the United States, or
         any other taxing authority, so that the net amounts received and
         retained by Trust __ after paying such expenses will be equal to the
         amounts Trust __ would have received had no such costs or expenses been
         incurred by or imposed on Trust __. The foregoing obligations of the
         Company are for the benefit of, and shall be enforceable by, any Person
         to whom any such debts, obligations, costs, expenses and taxes are owed
         (each, a "Creditor") whether or not such Creditor has received notice
         thereof. Any such Creditor may enforce such obligations of the Company
         directly against the Company, and the Company irrevocable waives any
         right or remedy to require that any such Creditor take any action
         against Trust __ or any other Person before proceeding against the
         Company."

         SECTION 2.        MISCELLANEOUS

     2.1 Form of __% Subordinated Debentures.  Attached hereto as Exhibit A is a
form of the __% Subordinated Debenture.

     2.2  Separability.  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.

     2.3 Continuance of Indenture. This _____ Supplemental Indenture supplements
the Indenture and shall be a part of and subject to all the terms  thereof.  The
Indenture, as supplemented by this _____ Supplemental Indenture,  shall continue
in full force and effect.

     2.4 The Trustee.  The Trustee shall not be responsible in any manner for or
in respect of the validity or sufficiency of this _____ Supplemental  Indenture,
or for or in respect of the recitals contained herein, all of which recitals are
made by the Company solely.

     2.5 Governing Law. This _____  Supplemental  Indenture shall be governed by
and construed in accordance with the laws of the State of New York.

     2.6 Defined Terms.  All capitalized  terms used in this _____  Supplemental
Indenture which are defined in the Indenture,  but not otherwise defined herein,
shall have the same meanings assigned to them in the Indenture.

     2.7 Counterparts.  This _____ Supplemental Indenture may be executed in any
number  of  counterparts,  each of which so  executed  shall be  deemed to be an
original,  but all such counterparts  shall together  constitute but one and the
same instrument.


     The  Chase   Manhattan  Bank  hereby  accepts  the  trusts  in  this  _____
Supplemental  Indenture  declared and  provided,  upon the terms and  conditions
hereinabove set forth.







                  IN WITNESS WHEREOF, the parties hereto have caused this _____
Supplemental Indenture, dated as of ____, 200_, to be duly executed, and their
respective Corporate seals to be hereunto affixed and attested, all as of ____,
200_.

                                      KEYSPAN CORPORATION




                                      By: _______________________________
                                      Name:
                                     Title:

Attest:


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                                    THE CHASE MANHATTAN BANK, as Trustee




                                    By: ________________________________
                                      Name:
                                     Title:

Attest:


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