2009 Series A 5.20% Senior Notes

Exhibit 4.3

DOMINION RESOURCES, INC.

Issuer

AND

DEUTSCHE BANK TRUST COMPANY AMERICAS

Series Trustee

Thirty-Ninth Supplemental Indenture

Dated as of August 1, 2009

$500,000,000

2009 Series A 5.20% Senior Notes

due 2019

TABLE OF CONTENTS*

ARTICLE I

2009 SERIES A 5.20%

SENIOR NOTES DUE 2019

THIS THIRTY-NINTH SUPPLEMENTAL INDENTURE is made as of the first day of August, 2009, by and between DOMINION RESOURCES, INC., a Virginia corporation, having its principal office at 120 Tredegar Street, Richmond, Virginia 23219 (the “Company”), and DEUTSCHE BANK TRUST COMPANY AMERICAS, a New York banking corporation, as Trustee of the series of Securities established by this Thirty-Ninth Supplemental Indenture, having a corporate trust office at 60 Wall Street, 27 ^th Floor, New York, New York 10005 (herein called the “Series Trustee”).

W I T N E S S E T H:

WHEREAS, the Company has heretofore entered into an Indenture dated as of June 1, 2000, between the Company and The Bank of New York Mellon (successor to JPMorgan Chase Bank, N.A. (formerly known as The Chase Manhattan Bank)) (the “Original Trustee”), as amended by the Thirty-Eighth Supplemental and Amending Indenture dated as of November 1, 2008 (as so amended, the “Base Indenture”), by and among the Company, the Original Trustee and the Series Trustee;

WHEREAS, the Base Indenture is incorporated herein by this reference and the Base Indenture, as heretofore supplemented, as further supplemented by this Thirty-Ninth Supplemental Indenture, and as may be hereafter supplemented or amended from time to time, is herein called the “Indenture”;

WHEREAS, under the Base Indenture, a new series of Securities may at any time be established in accordance with the provisions of the Base Indenture and the terms of such series may be described by a supplemental indenture executed by the Company and the Series Trustee;

WHEREAS, the Company proposes to create under the Indenture a new series of Securities and to appoint the Series Trustee as Trustee under the Base Indenture with respect to such series of Securities;

WHEREAS, additional Securities of other series hereafter established, except as may be limited in the Base Indenture as at the time supplemented and modified, may be issued from time to time pursuant to the Indenture as at the time supplemented and modified; and the Original Trustee will, unless and until a Person other than the Original Trustee is appointed to act as Trustee with respect to the Securities of such series, serve as Trustee of such series;

WHEREAS, all conditions necessary to authorize the execution and delivery of this Thirty-Ninth Supplemental Indenture and to make it a valid and binding obligation of the Company have been done or performed.

NOW, THEREFORE, in consideration of the agreements and obligations set forth herein and for other good and valuable consideration, the sufficiency of which is hereby acknowledged, the parties hereto hereby agree as follows:

ARTICLE I

2009 SERIES A 5.20% SENIOR NOTES DUE 2019

SECTION 101. Establishment . There is hereby established a new series of Securities to be issued under the Indenture, to be designated as the Company’s 2009 Series A 5.20% Senior Notes due 2019 (the “Series A Senior Notes”).

There are to be authenticated and delivered $500,000,000 principal amount of Series A Senior Notes, and such principal amount of the Series A Senior Notes may be increased from time to time pursuant to Section 301(2) of the Indenture. All Series A Senior Notes need not be issued at the same time and such series may be reopened at any time, without the consent of any Holder, for issuances of additional Series A Senior Notes. Any such additional Series A Notes will have the same interest rate, maturity and other terms as those initially issued. Further Series A Senior Notes may also be authenticated and delivered as provided by Sections 304, 305, 306, 905 or 1107 of the Base Indenture.

The Series A Senior Notes shall be issued in definitive fully registered form without coupons, in substantially the form set out in Exhibit A hereto. The entire initially issued principal amount of the Series A Senior Notes shall initially be evidenced by one or more certificates issued to Cede & Co., as nominee for The Depository Trust Company.

The form of the Series Trustee’s Certificate of Authentication for the Series A Senior Notes shall be in substantially the form set forth in Exhibit B hereto.

Each Series A Senior Note shall be dated the date of authentication thereof and shall bear interest from the date of original issuance thereof or from the most recent Interest Payment Date to which interest has been paid or duly provided for.

SECTION 102. Definitions . The following defined terms used herein shall, unless the context otherwise requires, have the meanings specified below. Capitalized terms used herein for which no definition is provided herein shall have the meanings set forth in the Base Indenture.

“Adjusted Treasury Rate” means, with respect to any Redemption Date: (i) the yield, under the heading which represents the average for the immediately preceding week, appearing in the most recently published statistical release designated “H.15(519)” or any successor publication which is published weekly by the Board of Governors of the Federal Reserve System and which establishes yields on actively traded United States Treasury securities adjusted to constant maturity under the caption “Treasury Constant Maturities,” for the maturity corresponding to the Comparable Treasury Issue (if no maturity is within three months before or after the Remaining Life, yields for the two published maturities most closely corresponding to the Comparable Treasury Issue will be determined and the Adjusted Treasury Rate will be interpolated or extrapolated from such yields on a straight line basis, rounding to the nearest month); or (ii) if such release (or any successor release) is not published during the week preceding the calculation date or does not contain such yields, the rate per annum equal to the semi-annual equivalent yield to maturity of the Comparable Treasury Issue, calculated using a price for the Comparable Treasury Issue (expressed as a percentage of its principal amount) equal to the Comparable Treasury Price for such Redemption Date.

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“Business Day” means a day other than (i) a Saturday or a Sunday, (ii) a day on which banks in New York, New York are authorized or obligated by law or executive order to remain closed or (iii) a day on which the Corporate Trust Office of the Series Trustee is closed for business.

“Comparable Treasury Issue” means the United States Treasury security selected by an Independent Investment Banker as having a maturity comparable to the remaining term of the Series A Senior Notes to be redeemed that would be utilized, at the time of selection and in accordance with customary financial practice, in pricing new issues of corporate debt securities of comparable maturity to the Remaining Life.

“Comparable Treasury Price” for any Redemption Date means (i) the average of the Reference Treasury Dealer Quotations for such Redemption Date, after excluding the highest and lowest Reference Treasury Dealer Quotations, or (ii) if the Independent Investment Banker obtains fewer than five such Reference Treasury Dealer Quotations, the average of all such quotations.

“Corporate Trust Office of the Series Trustee” means the office of the Series Trustee at which at any particular time its corporate trust business with respect to the series of Securities herein described shall be principally administered, which office at the date of original execution of this Thirty-Ninth Supplemental Indenture is located at 60 Wall Street, 27 ^th Floor, New York, New York 10005 (in addition copies of correspondence are to be sent to Deutsche Bank National Trust Company for Deutsche Bank Trust Company Americas, 25 DeForst Avenue, Mail Stop 0105, Summit, New Jersey, 07901).

“Independent Investment Banker” means any of BNP Paribas Securities Corp., Deutsche Bank Securities Inc., J. P. Morgan Securities Inc. or Morgan Stanley & Co. Incorporated, and their respective successors as selected by the Company, or if any such firm is unwilling or unable to serve as such, an independent investment and banking institution of national standing appointed by the Company.

“Interest Payment Dates” means February 15 and August 15 of each year, commencing on February 15, 2010.

“Lien” means any mortgage, lien, pledge, security interest or other encumbrance of any kind.

“Material Subsidiary” means a Subsidiary of the Company whose total assets (as determined in accordance with GAAP) represent at least 20% of the total assets of the Company on a consolidated basis.

“Original Issue Date” means August 14, 2009.

“Outstanding”, when used with respect to the Series A Senior Notes, means, as of the date of determination, all Series A Senior Notes, theretofore authenticated and delivered under the Indenture, except:

(i) Series A Senior Notes theretofore canceled by the Series Trustee or delivered to the Series Trustee for cancellation;

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(ii) Series A Senior Notes for whose payment at Maturity the necessary amount of money or money’s worth has been theretofore deposited (other than pursuant to Section 402 of the Base Indenture) with the Series Trustee or any Paying Agent (other than the Company) in trust or set aside and segregated in trust by the Company (if the Company shall act as its own Paying Agent) for the Holders of such Series A Senior Notes;

(iii) Series A Senior Notes with respect to which the Company has effected defeasance or covenant defeasance has been effected pursuant to Section 402 of the Base Indenture; and

(iv) Series A Senior Notes that have been paid pursuant to Section 306 of the Base Indenture or in exchange for or in lieu of which other Series A Senior Notes have been authenticated and delivered pursuant to the Indenture, other than any such Series A Senior Notes in respect of which there shall have been presented to the Series Trustee proof satisfactory to it that such Series A Senior Notes are held by a bona fide purchaser in whose hands such Series A Senior Notes are valid obligations of the Company; provided, however, that in determining whether the Holders of the requisite principal amount of Outstanding Series A Senior Notes have given any request, demand, authorization, direction, notice, consent or waiver hereunder or are present at a meeting of Holders of Series A Senior Notes for quorum purposes, Series A Senior Notes owned by the Company or any other obligor upon the Series A Senior Notes or any Affiliate of the Company or such other obligor shall be disregarded and deemed not to be Outstanding, except that, in determining whether the Series Trustee shall be protected in making any such determination or relying upon any such request, demand, authorization, direction, notice, consent or waiver, only Series A Senior Notes which the Series Trustee actually knows to be so owned shall be so disregarded. Series A Senior Notes so owned which shall have been pledged in good faith may be regarded as Outstanding if the pledgee establishes to the satisfaction of the Series Trustee (A) the pledgee’s right so to act with respect to such Series A Senior Notes and (B) that the pledgee is not the Company or any other obligor upon the Series A Senior Notes or an Affiliate of the Company or such other obligor.

“Principal Property” means any plant or facility of the Company located in the United States that in the opinion of the Board of Directors or management of the Company is of material importance to the business conducted by the Company and its consolidated Subsidiaries taken as whole.

“Reference Treasury Dealer” means: (i) BNP Paribas Securities Corp., Deutsche Bank Securities Inc., J. P. Morgan Securities Inc. or Morgan Stanley & Co. Incorporated and their respective successors; provided that, if any such firm or its successors ceases to be a primary U.S. Government securities dealer in the United States (a “Primary Treasury Dealer”), the Company shall substitute another Primary Treasury Dealer; and (ii) up to one other Primary Treasury Dealer selected by the Company.

“Reference Treasury Dealer Quotations” means, with respect to each Reference Treasury Dealer and any Redemption Date, the average, as determined by the Independent Investment Banker, of the bid and asked prices for the Comparable Treasury Issue (expressed in each case as a percentage of its principal amount) quoted in writing to the Independent Investment Banker at 5:00 p.m., New York City time, on the third Business Day preceding such Redemption Date.

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“Regular Record Date” means, with respect to each Interest Payment Date, the close of business on the Business Day preceding such Interest Payment Date; provided , that with respect to Series A Senior Notes that are not represented by one or more Global Securities, the Regular Record Date shall be the close of business on the 15th calendar day (whether or not a Business Day) preceding such Interest Payment Date.

“Remaining Life” means the remaining term of the Series A Senior Notes.

“Stated Maturity” means August 15, 2019.

The terms “Company,” “Original Trustee,” “Series Trustee,” “Base Indenture,” and “Indenture” shall have the respective meanings set forth in the recitals to this Thirty-Ninth Supplemental Indenture and the paragraph preceding such recitals.

SECTION 103. Payment of Principal and Interest . The principal of the Series A Senior Notes shall be due at the Stated Maturity (unless earlier redeemed). The unpaid principal amount of the Series A Senior Notes shall bear interest at the rate of 5.20% per annum until paid or duly provided for, such interest to accrue from the Original Issue Date or from the most recent Interest Payment Date to which interest has been paid or duly provided for. Interest shall be paid semi-annually in arrears on each Interest Payment Date to the Person in whose name the Series A Senior Notes are registered on the Regular Record Date for such Interest Payment Date; provided that interest payable at the Stated Maturity of principal, on a Redemption Date or a Repayment Date as provided herein will be paid to the Person to whom principal is payable. Any such interest that is not so punctually paid or duly provided for will forthwith cease to be payable to the Holders on such Regular Record Date and may either be paid to the Person or Persons in whose name the Series A Senior Notes are registered at the close of business on a Special Record Date for the payment of such defaulted interest to be fixed by the Series Trustee (in accordance with Section 307 of the Base Indenture), notice whereof shall be given to Holders of the Series A Senior Notes not less than ten (10) days prior to such Special Record Date, or be paid at any time in any other lawful manner not inconsistent with the requirements of any securities exchange, if any, on which the Series A Senior Notes may be listed, and upon such notice as may be required by any such exchange, all as more fully provided in the Base Indenture.

Payments of interest on the Series A Senior Notes will include interest accrued to but excluding the respective Interest Payment Dates. Interest payments for the Series A Senior Notes shall be computed and paid on the basis of a 360-day year of twelve 30-day months. In the event that any date on which interest is payable on the Series A Senior Notes is not a Business Day, then payment of the interest payable on such date will be made on the next succeeding day that is a Business Day (and without any interest or payment in respect of any such delay), in each case with the same force and effect as if made on the date the payment was originally payable.

Payment of the principal and interest on the Series A Senior Notes shall be made at the office of the Paying Agent in such coin or currency of the United States of America as at the time of payment is legal tender for payment of public and private debts, with any such payment

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that is due at the Stated Maturity of any Series A Senior Notes, upon redemption or repurchase being made upon surrender of such Series A Senior Notes to the Paying Agent. Payments of interest (including interest on any Interest Payment Date) will be made, subject to such surrender where applicable, at the option of the Company, (i) by check mailed to the address of the Person entitled thereto as such address shall appear in the Security Register or (ii) by wire transfer at such place and to such account at a banking institution in the United States as may be designated in writing to the Series Trustee at least sixteen (16) days prior to the date for payment by the Person entitled thereto. In the event that any date on which principal and interest is payable on the Series A Senior Notes is not a Business Day, then payment of the principal and interest payable on such date will be made on the next succeeding day that is a Business Day (and without any interest or payment in respect of any such delay), in each case with the same force and effect as if made on the date the payment was originally payable.

SECTION 104. Denominations . The Series A Senior Notes may be issued in denominations of $1,000, or any greater integral multiple of $1,000.

SECTION 105. Global Securities . The Series A Senior Notes will be issued initially in the form of one or more Global Securities registered in the name of the Depositary (which shall be The Depository Trust Company) or its nominee. Except under the limited circumstances described below, Series A Senior Notes represented by such Global Securities will not be exchangeable for, and will not otherwise be issuable as, Series A Senior Notes in definitive form. The Global Securities described above may not be transferred except by the Depositary to a nominee of the Depositary or by a nominee of the Depositary to the Depositary or another nominee of the Depositary or to a successor Depositary or its nominee.

Owners of beneficial interests in such a Global Security will not be considered the Holders thereof for any purpose under the Indenture, and no Global Security representing a Series A Senior Note shall be exchangeable, except for another Global Security of like denomination and tenor to be registered in the name of the Depositary or its nominee or to a successor Depositary or its nominee or except as described below. The rights of Holders of such Global Security shall be exercised only through the Depositary.

A Global Security shall be exchangeable for Series A Senior Notes registered in the names of persons other than the Depositary or its nominee only if (i) the Depositary notifies the Company that it is unwilling or unable to continue as a Depositary for such Global Security and no successor Depositary shall have been appointed by the Company within 90 days of receipt by the Company of such notification, or if at any time the Depositary ceases to be a clearing agency registered under the Exchange Act at a time when the Depositary is required to be so registered to act as such Depositary and no successor Depositary shall have been appointed by the Company within 90 days after it becomes aware of such cessation, or (ii) the Company in its sole discretion determines that such Global Security shall be so exchangeable, in which case Series A Senior Notes in definitive form will be printed and delivered to the Depositary. Any Global Security that is exchangeable pursuant to the preceding sentence shall be exchangeable for Series A Senior Notes registered in such names as the Depositary shall direct.

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SECTION 106. Redemption . The Series A Senior Notes are redeemable, in whole or in part, at any time, and at the option of the Company, at a Redemption Price equal to the greater of:

(i) 100% of the principal amount of Series A Senior Notes then Outstanding to be so redeemed, or

(ii) the sum of the present values of the remaining scheduled payments of principal and interest thereon (not including any portion of such payments of interest accrued as of the Redemption Date) discounted to the Redemption Date on a semi-annual basis (assuming a 360-day year consisting of twelve 30-day months) at the Adjusted Treasury Rate, plus 25 basis points, as calculated by an Independent Investment Banker,

plus, in either of the above cases, accrued and unpaid interest thereon to the Redemption Date.

Unless the Company defaults in the payment of the Redemption Price, on and after the Redemption Date, interest will cease to accrue on the Series A Senior Notes or portions thereof called for redemption.

The Adjusted Treasury Rate shall be calculated on the third Business Day preceding the Redemption Date.

In the event of the redemption of the Series A Senior Notes in part only, a new Series A Senior Note or Notes for the unredeemed portion will be issued in the name or names of the Holders thereof upon surrender thereof.

The Company shall notify the Series Trustee of the Redemption Price promptly after the calculation thereof and the Series Trustee shall have no responsibility for such calculation.

SECTION 107. Sinking Fund . The Series A Senior Notes shall not have a sinking fund.

SECTION 108. Additional Interest . Any principal of and installment of interest on the Series A Senior Notes that is overdue shall bear interest at the rate of 5.20%