Exhibit 4(a) TEXAS UTILITIES ELECTRIC COMPANY TO THE BANK OF NEW YORK, (formerly Irving Trust Company) Trustee under the Texas Utilities Electric Company Mortgage and Deed of Trust, dated as of December 1, 1983 ------------------ Fifty-ninth Supplemental Indenture Providing among other things for First Mortgage Bonds, Pollution Control Series AK ------------------ Dated as of March 1, 1999 This Instrument Grants a Security Interest by a Utility This Instrument Contains After-Acquired Property Provisions This Instrument Grants a Security Interest by a Utility This Instrument Contains After-Acquired Property Provisions FIFTY-NINTH SUPPLEMENTAL INDENTURE --------------------------------- INDENTURE, dated as of March 1, 1999, between TEXAS UTILITIES ELECTRIC COMPANY, a corporation of the State of Texas, whose address is Energy Plaza, 1601 Bryan Street, Dallas, Texas 75201 (hereinafter sometimes called the Company), and THE BANK OF NEW YORK (formerly Irving Trust Company), a corporation of the State of New York, whose address is 101 Barclay Street, New York, New York 10286 (hereinafter sometimes called the Trustee), Trustee under the Mortgage and Deed of Trust, dated as of December 1, 1983 (hereinafter called the Original Indenture, the Original Indenture and any and all indentures and instruments supplemental thereto being hereinafter sometimes collectively called the Mortgage), which Original Indenture was executed and delivered by the Company to secure the payment of bonds issued or to be issued under and in accordance with the provisions of the Mortgage, reference to which Mortgage is made, this Indenture (hereinafter called the Fifty-ninth Supplemental Indenture) being supplemental thereto; WHEREAS, said Original Indenture was recorded or filed as required in the State of Texas; and WHEREAS, the Company executed and delivered to the Trustee the following supplemental indentures: Designation Dated as of ----------- ----------- First Supplemental Indenture.............................. April 1, 1984 Second Supplemental Indenture............................. September 1, 1984 Third Supplemental Indenture.............................. April 1, 1985 Fourth Supplemental Indenture............................. August 1, 1985 Fifth Supplemental Indenture.............................. September 1, 1985 Sixth Supplemental Indenture.............................. December 1, 1985 Seventh Supplemental Indenture............................ March 1, 1986 Eighth Supplemental Indenture............................. May 1, 1986 Ninth Supplemental Indenture.............................. October 1, 1986 Tenth Supplemental Indenture.............................. December 1, 1986 Eleventh Supplemental Indenture........................... December 1, 1986 Twelfth Supplemental Indenture............................ February 1, 1987 Thirteenth Supplemental Indenture......................... March 1, 1987 Fourteenth Supplemental Indenture......................... April 1, 1987 Fifteenth Supplemental Indenture.......................... July 1, 1987 Sixteenth Supplemental Indenture.......................... September 1, 1987 Seventeenth Supplemental Indenture........................ October 1, 1987 Eighteenth Supplemental Indenture......................... March 1, 1988 Nineteenth Supplemental Indenture......................... May 1, 1988 2 Designation Dated as of ----------- ----------- Twentieth Supplemental Indenture.......................... September 1, 1988 Twenty-first Supplemental Indenture....................... November 1, 1988 Twenty-second Supplemental Indenture...................... January 1, 1989 Twenty-third Supplemental Indenture....................... August 1, 1989 Twenty-fourth Supplemental Indenture...................... November 1, 1989 Twenty-fifth Supplemental Indenture....................... December 1, 1989 Twenty-sixth Supplemental Indenture....................... February 1, 1990 Twenty-seventh Supplemental Indenture..................... September 1, 1990 Twenty-eighth Supplemental Indenture...................... October 1, 1990 Twenty-ninth Supplemental Indenture....................... October 1, 1990 Thirtieth Supplemental Indenture.......................... March 1, 1991 Thirty-first Supplemental Indenture....................... May 1, 1991 Thirty-second Supplemental Indenture...................... July 1, 1991 Thirty-third Supplemental Indenture....................... February 1, 1992 Thirty-fourth Supplemental Indenture...................... April 1, 1992 Thirty-fifth Supplemental Indenture....................... April 1, 1992 Thirty-sixth Supplemental Indenture....................... June 1, 1992 Thirty-seventh Supplemental Indenture..................... June 1, 1992 Thirty-eighth Supplemental Indenture...................... August 1, 1992 Thirty-ninth Supplemental Indenture....................... October 1, 1992 Fortieth Supplemental Indenture........................... November 1, 1992 Forty-first Supplemental Indenture........................ December 1, 1992 Forty-second Supplemental Indenture....................... March 1, 1993 Forty-third Supplemental Indenture........................ April 1, 1993 Forty-fourth Supplemental Indenture....................... April 1, 1993 Forty-fifth Supplemental Indenture........................ May 1, 1993 Forty-sixth Supplemental Indenture........................ July 1, 1993 Forty-seventh Supplemental Indenture...................... October 1, 1993 Forty-eighth Supplemental Indenture....................... November 1, 1993 Forty-ninth Supplemental Indenture........................ May 1, 1994 Fiftieth Supplemental Indenture........................... May 1, 1994 Fifty-first Supplemental Indenture........................ August 1, 1994 Fifty-second Supplemental Indenture....................... April 1, 1995 Fifty-third Supplemental Indenture........................ June 1, 1995 Fifty-fourth Supplemental Indenture....................... October 1, 1995 Fifty-fifth Supplemental Indenture........................ March 1, 1996 Fifty-sixth Supplemental Indenture........................ September 1, 1996 Fifty-seventh Supplemental Indenture...................... February 1, 1997 Fifty-eighth Supplemental Indenture....................... July 1, 1997 which supplemental indentures were or are to be recorded or filed as required in the State of Texas; and WHEREAS, by the Original Indenture, the Company covenanted that it would execute and deliver such supplemental indenture or indentures and such further instruments and do such further acts as may be necessary or proper to carry out more effectually the purposes of the Mortgage and to make subject to the Lien of the Mortgage any property thereafter acquired and intended to be subject to the Lien thereof; and 3 WHEREAS, in addition to the property described in the Original Indenture, the Company has acquired certain other property, rights and interests in property; and WHEREAS, the Company has heretofore issued as of February 28, 1999, in accordance with the provisions of the Original Indenture, as heretofore supplemented, the following series of First Mortgage and Collateral Trust Bonds and First Mortgage Bonds: Principal Principal Amount Amount Series Issued Outstanding 12% Series due March 1, 1985........................... $ 1,000,000 $ None 13 5/8% Series due April 1, 2014....................... 100,000,000 None 13 1/2% Series due September 1, 2014................... 150,000,000 None 12 7/8% Series due April 1, 2015....................... 150,000,000 None 12% Series due August 1, 2015.......................... 100,000,000 None 12% Series due September 1, 2015....................... 75,000,000 None 11 1/8% Series due December 1, 2015.................... 150,000,000 None 9 3/8% Series due March 1, 2016........................ 200,000,000 None 9 3/4% Series due May 1, 2016.......................... 200,000,000 None Pollution Control Series C............................. 70,000,000 None Pollution Control Series D............................. 200,000,000 None 9 1/2% Series due December 1, 2016..................... 300,000,000 None 9 1/4% Series due February 1, 2017..................... 250,000,000 None Pollution Control Series E............................. 100,000,000 None 10 1/2% Series due April 1, 2017....................... 250,000,000 None 9 1/2% Series due July 1, 1997......................... 150,000,000 None 10 1/2% Series due July 1, 2017........................ 150,000,000 None Pollution Control Series F ............................ 55,000,000 None Pollution Control Series G ............................ 12,000,000 None Pollution Control Series H ............................ 112,000,000 None Pollution Control Series I ............................ 100,000,000 None 10 3/8% Series due May 1, 1998......................... 150,000,000 None 11 3/8% Series due May 1, 2018......................... 150,000,000 None Secured Medium-Term Notes, Series A.................... 300,000,000 None 10.44% Series due November 1, 2008..................... 150,000,000 3,000,000 Pollution Control Series J ............................ 100,000,000 100,000,000 9 1/2% Series due August 1, 1999....................... 200,000,000 200,000,000 10% Series due August 1, 2019.......................... 100,000,000 None 9 7/8% Series due November 1, 2019..................... 150,000,000 None Secured Medium-Term Notes, Series B.................... 150,000,000 114,200,000 Pollution Control Series K ............................ 50,000,000 50,000,000 Pollution Control Series L ............................ 40,000,000 40,000,000 10 5/8% Series due September 1, 2020................... 250,000,000 None Secured Medium-Term Notes, Series C.................... 150,000,000 None 8 1/4% Pollution Control Series due October 1, 2020.... 11,000,000 11,000,000 7 7/8% Pollution Control Series due March 1, 2021...... 100,000,000 100,000,000 9 3/4% Series due May 1, 2021.......................... 300,000,000 133,047,000 Pollution Control Series M due June 1, 2021 ........... 86,250,000 None Pollution Control Series N due June 1, 2021 ........... 57,500,000 None Pollution Control Series O due June 1, 2021 ........... 57,500,000 None 4 Pollution Control Series P due June 1, 2021 ........... $115,000,000 $ 18,325,250 8 1/8% Series due February 1, 2002..................... 150,000,000 150,000,000 8 7/8% Series due February 1, 2022..................... 175,000,000 117,200,000 8 1/4% Series due April 1, 2004........................ 100,000,000 100,000,000 9% Series due April 1, 2022............................ 100,000,000 None 6 3/4% Pollution Control Series due April 1, 2022...... 50,000,000 50,000,000 7 1/8% Series due June 1, 1997......................... 150,000,000 None 8% Series due June 1, 2002............................. 147,000,000 147,000,000 6 5/8% Pollution Control Series due June 1, 2022....... 33,000,000 33,000,000 6 3/8% Series due August 1, 1997....................... 175,000,000 None 7 3/8% Series due August 1, 2001....................... 150,000,000 150,000,000 8 1/2% Series due August 1, 2024....................... 175,000,000 127,000,000 6.70% Pollution Control Series due October 1, 2022..... 16,935,000 16,935,000 6.55% Pollution Control Series due October 1, 2022..... 40,000,000 40,000,000 7 3/8% Series due November 1, 1999..................... 100,000,000 100,000,000 8 3/4% Series due November 1, 2023..................... 200,000,000 121,950,000 6 1/2% Pollution Control Series due December 1, 2027... 46,660,000 46,660,000 6 3/4% Series due March 1, 2003........................ 200,000,000 200,000,000 7 7/8% Series due March 1, 2023........................ 300,000,000 168,100,000 6.05% Pollution Control Series due April 1, 2025....... 90,000,000 90,000,000 6.10% Pollution Control Series due April 1, 2028....... 50,000,000 50,000,000 5 7/8% Series due April 1, 1998........................ 175,000,000 None 6 3/4% Series due April 1, 2003........................ 100,000,000 100,000,000 7 7/8% Series due April 1, 2024........................ 225,000,000 150,183,000 Pollution Control Series due June 1, 2023.............. 115,000,000 115,000,000 5 3/4% Series due July 1, 1998......................... 150,000,000 None 6 3/4% Series due July 1, 2005......................... 100,000,000 90,000,000 7 5/8% Series due July 1, 2025......................... 250,000,000 210,000,000 5 1/2% Series due October 1, 1998...................... 125,000,000 None 6 1/4% Series due October 1, 2004...................... 125,000,000 115,000,000 7 3/8% Series due October 1, 2025...................... 300,000,000 193,000,000 5 1/2% Pollution Control Series due May 1, 2022........ 50,000,000 50,000,000 5.55% Pollution Control Series due May 1, 2022......... 75,000,000 75,000,000 5.85% Pollution Control Series due May 1, 2022......... 33,465,000 33,465,000 Floating Rate Series due May 1, 1999................... 300,000,000 None Pollution Control Series Q due May 1, 2029............. 45,045,500 45,045,500 Pollution Control Series R due May 1, 2029............. 45,045,500 45,045,500 0% Series due 1994..................................... 1,013,831,000 None Pollution Control Series S due April 1, 2030........... 58,270,500 58,270,500 Pollution Control Series T due April 1, 2030........... 18,400,000 18,400,000 Pollution Control Series U............................. 136,108,250 136,108,250 Pollution Control Series V............................. 136,108,250 136,108,250 Pollution Control Series W............................. 13,857,500 13,857,500 Pollution Control Series X............................. 21,246,250 21,246,250 Secured Medium-Term Notes, Series D.................... 201,150,000 201,150,000 Pollution Control Series Y............................. 28,819,000 28,819,000 Pollution Control Series Z............................. 66,642,500 66,642,500 Pollution Control Series AA............................ 28,750,000 28,750,000 Pollution Control Series AB............................ 28,750,000 28,750,000 Pollution Control Series AC............................ 70,397,250 70,397,250 Pollution Control Series AD............................ 57,500,000 57,500,000 5 Pollution Control Series AE............................ 57,500,000 57,500,000 Pollution Control Series AF............................ 36,000,750 36,000,750 Pollution Control Series AG............................ 28,801,750 28,801,750 Pollution Control Series AH............................ 33,079,750 33,079,250 Pollution Control Series AI .......................... 59,253,750 59,253,750 Pollution Control Series AJ ........................... 13,800,000 13,800,000 which bonds are also hereinafter sometimes called bonds of the First through Ninety-seventh Series, respectively; and WHEREAS, Section 2.01 of the Original Indenture provides that the form of each series of bonds (other than the First Series) issued thereunder and of the coupons to be attached to coupon bonds of such series shall be established by Resolution of the Board of Directors of the Company, and that the form of such series, as established by said Board of Directors, shall specify the descriptive title of the bonds and various other terms thereof, and may also have such omissions or modifications or contain such provisions not prohibited by the provisions of the Mortgage as the Board of Directors may, in its discretion, cause to be inserted therein expressing or referring to the terms and conditions upon which such bonds are to be issued and/or secured under the Mortgage; and WHEREAS, Section 22.04 of the Original Indenture provides, among other things, that any power, privilege or right expressly or impliedly reserved to or in any way conferred upon the Company by any provision of the Mortgage, whether such power, privilege or right is in any way restricted or is unrestricted, may be in whole or in part waived or surrendered or subjected to any restriction if at the time unrestricted, or to additional restriction if already restricted, and the Company may enter into any further covenants, limitations, restrictions or provisions for the benefit of any one or more series of bonds issued thereunder, or the Company may cure any ambiguity contained therein, or in any supplemental indenture, or may establish the terms and provisions of any series of bonds other than the First Series, by an instrument in writing executed and acknowledged by the Company in such manner as would be necessary to entitle a conveyance of real estate to be recorded in all of the states in which any property at the time subject to the Lien of the Mortgage shall be situated; and WHEREAS, the Company now desires to create a new series of bonds and to add to its covenants and agreements contained in the Mortgage certain other covenants and agreements to be observed by it and to alter and amend in certain respects the covenants and provisions contained in the Mortgage; and WHEREAS, the execution and delivery by the Company of this Fifty-ninth Supplemental Indenture, and the terms of the bonds of the Ninety-eighth Series, hereinafter referred to, have been duly authorized by the Board of Directors of the Company by appropriate resolutions of said Board of Directors; 6 NOW, THEREFORE, THIS INDENTURE WITNESSETH: That the Company, in consideration of the premises and of Ten Dollars to it duly paid by the Trustee at or before the ensealing and delivery of these presents, the receipt whereof is hereby acknowledged, and in order to secure the payment of both the principal of and interest and premium, if any, on the bonds from time to time issued under the Mortgage, according to their tenor and effect and the performance of all the provisions of the Mortgage (including any instruments supplemental thereto and any modification made as in the Mortgage provided) and of said bonds, hath granted, bargained, sold, released, conveyed, assigned, transferred, mortgaged, hypothecated, affected, pledged, set over and confirmed and granted a security interest in and by these presents doth grant, bargain, sell, release, convey, assign, transfer, mortgage, hypothecate, affect, pledge, set over and confirm and grant a security interest in (subject, however, to Excepted Encumbrances as defined in Section 1.06 of the Original Indenture) unto The Bank of New York, Trustee under the Mortgage, and to its successor or successors in said trust, and to said Trustee and its successors and assigns forever, all properties of the Company, real, personal and mixed, of the kind or nature specifically mentioned in the Original Indenture, as heretofore supplemented, or of any other kind or nature acquired by the Company on or after the date of the execution and delivery of the Original Indenture (except any herein or in the Original Indenture expressly excepted), now owned or, subject to the provisions of Section 18.03 of the Original Indenture, hereafter acquired by the Company (by purchase, consolidation, merger, donation, construction, erection or in any other way) and wheresoever situated, including (without in anywise limiting or impairing by the enumeration of the same, the scope and intent of the foregoing or of any general description contained in this Fifty-ninth Supplemental Indenture) all real estate, lands, easements, servitudes, licenses, permits, franchises, privileges, rights of way and other rights in or relating to real estate or the occupancy of the same; all power sites, flowage rights, water rights, water locations, water appropriations, ditches, flumes, reservoirs, reservoir sites, canals, raceways, waterways, dams, dam sites, aqueducts, and all other rights or means for appropriating, conveying, storing and supplying water; all rights of way and roads; all plants for the generation of electricity by steam, water and/or other power; all power houses, gas plants, street lighting systems, standards and other equipment incidental thereto; all telephone, radio and television systems, air-conditioning systems and equipment incidental thereto, water wheels, water works, water systems, steam heat and hot water plants, substations, lines, service and supply systems, bridges, culverts, tracks, ice or refrigeration plants and equipment, offices, buildings and other structures and the equipment thereof; all machinery, engines, boilers, dynamos, turbines, electric, gas and other machines, prime movers, regulators, meters, transformers, generators (including, but not limited to, engine driven generators and turbo-generator units), motors, electrical, gas and mechanical appliances, conduits, cables, water, steam heat, gas or other pipes, gas mains and pipes, service pipes, fittings, valves and connections, pole and transmission lines, towers, overhead conductors and devices, underground conduits, underground conductors and devices, wires, cables, tools, implements, apparatus, storage battery equipment, and all other fixtures and personalty; all municipal and other franchises, consents or permits; all lines for the transmission and distribution of electric current, gas, steam heat or water for any purpose including towers, poles, wires, cables, pipes, conduits, ducts and all apparatus for use in connection therewith and (except as herein or in the Original Indenture expressly excepted) all the right, title and interest of the 7 Company in and to all other property of any kind or nature appertaining to and/or used and/or occupied and/or enjoyed in connection with any property hereinbefore or in the Original Indenture described. TOGETHER WITH all and singular the tenements, hereditaments, prescriptions, servitudes and appurtenances belonging or in anywise appertaining to the aforesaid property or any part thereof, with the reversion and reversions, remainder and remainders and (subject to the provisions of Section 13.01 of the Original Indenture) the tolls, rents, revenues, issues, earnings, income, product and profits thereof, and all the estate, right, title and interest and claim whatsoever, at law as well as in equity, which the Company now has or may hereafter acquire in and to the aforesaid property and franchises and every part and parcel thereof. IT IS HEREBY AGREED by the Company that, subject to the provisions of Section 18.03 of the Original Indenture, all the property, rights and franchises acquired by the Company (by purchase, consolidation, merger, donation, construction, erection or in any other way) after the date hereof, except any herein or in the Original Indenture expressly excepted, shall be and are as fully granted and conveyed hereby and as fully embraced within the Lien of the Original Indenture and the Lien hereof as if such property, rights and franchises were now owned by the Company and were specifically described herein and conveyed hereby. PROVIDED that the following are not and are not intended to be now or hereafter granted, bargained, sold, released, conveyed, assigned, transferred, mortgaged, hypothecated, affected, pledged, set over or confirmed hereunder, nor is a security interest therein hereby or by the Original Indenture, as heretofore supplemented, granted or intended to be granted, and the same are hereby expressly excepted from the Lien and operation of the Original Indenture, as heretofore supplemented, and from the Lien and operation of this Fifty-ninth Supplemental Indenture, viz.: (1) cash, shares of stock, bonds, notes and other obligations and other securities not hereinbefore or hereafter specifically pledged, paid, deposited, delivered or held under the Mortgage or covenanted so to be; (2) merchandise, equipment, apparatus, materials or supplies held for the purpose of sale or other disposition in the usual course of business or for the purpose of repairing or replacing (in whole or in part) any rolling stock, buses, motor coaches, automobiles or other vehicles or aircraft or boats, ships, or other vessels and any fuel, oil and similar materials and supplies consumable in the operation of any of the properties of the Company; rolling stock, buses, motor coaches, automobiles and other vehicles and all aircraft; boats, ships and other vessels; all timber, minerals, mineral rights and royalties; (3) bills, notes and other instruments and accounts receivable, judgments, demands, general intangibles and choses in action, and all contracts, leases and operating agreements not specifically pledged hereunder or under the Mortgage or covenanted so to be; (4) the last day of the term of any lease or leasehold which may hereafter become subject to the Lien of the Mortgage; (5) electric energy, gas, water, steam, ice, and other materials or products generated, manufactured, produced, or purchased by the Company for sale, distribution or use in the ordinary course of its business; (6) any natural gas wells or natural gas leases or natural gas transportation lines or other works or property used 8 primarily and principally in the production of natural gas or its transportation, primarily for the purpose of sale to natural gas customers or to a natural gas distribution or pipeline company, up to the point of connection with any distribution system; and (7) the Company's franchise to be a corporation; provided, however, that the property and rights expressly excepted from the Lien and operation of the Original Indenture and this Fifty-ninth Supplemental Indenture in the above subdivisions (2) and (3) shall (to the extent permitted by law) cease to be so excepted in the event and as of the date that the Trustee or a receiver or trustee shall enter upon and take possession of the Mortgaged and Pledged Property in the manner provided in Article XV of the Original Indenture by reason of the occurrence of a Default. TO HAVE AND TO HOLD all such properties, real, personal and mixed, granted, bargained, sold, released, conveyed, assigned, transferred, mortgaged, hypothecated, affected, pledged, set over or confirmed or in which a security interest has been granted by the Company as aforesaid, or intended so to be (subject, however, to Excepted Encumbrances as defined in Section 1.06 of the Original Indenture), unto The Bank of New York, Trustee, and its successors and assigns forever. IN TRUST NEVERTHELESS, for the same purposes and upon the same terms, trusts and conditions and subject to and with the same provisos and covenants as are set forth in the Original Indenture, as heretofore supplemented, this Fifty-ninth Supplemental Indenture being supplemental to the Original Indenture. AND IT IS HEREBY COVENANTED by the Company that all the terms, conditions, provisos, covenants and provisions contained in the Original Indenture, as heretofore supplemented, shall affect and apply to the property hereinbefore described and conveyed and to the estate, rights, obligations and duties of the Company and the Trustee and the beneficiaries of the trust with respect to said property, and to the Trustee and its successors as Trustee of said property, in the same manner and with the same effect as if said property had been owned by the Company at the time of the execution of the Original Indenture, and had been specifically and at length described in and conveyed to said Trustee by the Original Indenture as a part of the property therein stated to be conveyed. The Company further covenants and agrees to and with the Trustee and its successors in said trust under the Mortgage, as follows: ARTICLE I Ninety-eighth Series of Bonds SECTION 1. There shall be a series of bonds designated "Pollution Control Series AK" (herein sometimes referred to as the "Ninety-eighth Series"), each of which shall also bear the descriptive title "First Mortgage Bond", and the form thereof, which shall be established in accordance with a Resolution of the Board of Directors of the Company, shall contain suitable provisions with respect to the matters hereinafter in this Section specified. Bonds of the Ninety-eighth Series may be issued in one or more tranches and may be issued with up to one 9 month's accrued interest. Bonds of the Ninety-eighth Series shall be issued as fully registered bonds in denominations of One Dollar and, at the option of the Company, in any multiple or multiples thereof (the exercise of such option to be evidenced by the execution and delivery thereof); Bonds of the Ninety-eighth Series shall mature on such date not later than the maturity date of the Series 1999A Brazos Revenue Bonds, referred to below, shall bear interest at such rate or rates, payable on such date or dates, and have such other terms and provisions not inconsistent with the Original Indenture as the proper officer or officers of the Company may determine in accordance with one or more Resolutions filed with the Trustee referring to this Fifty-ninth Supplemental Indenture (such determinations shall be evidenced by or in accordance with one or more written orders filed with the Trustee for the authentication and delivery of bonds of the Ninety-eighth Series and shall constitute determinations of the Board of Directors with respect to such bonds for purposes of the Mortgage), the principal of each said bond to be payable at the office or agency of the Company in the Borough of Manhattan, The City of New York, New York, or at the office or agency of the Company in the City of Dallas, Texas, as the holder of any said bond may elect, in such coin or currency of the United States of America as at the time of payment is legal tender for public and private debts. Bonds of the Ninety-eighth Series shall be dated as in Section 2.03 of the Original Indenture provided. (I) The bonds of the Ninety-eighth Series shall be initially issued in an aggregate principal amount not to exceed $123,036,585 to, and registered in the name of, the trustee under the Trust Indenture, dated as of March 1, 1999 (hereinafter sometimes called the "1999A Brazos Bond Indenture"), of the Brazos River Authority (hereinafter sometimes called the "Brazos Authority"), under which its Collateralized Pollution Control Revenue Refunding Bonds (Texas Utilities Electric Company Project), Series 1999A (hereinafter sometimes called the "Series 1999A Brazos Revenue Bonds") are to be issued, in order to provide the benefit of a lien to secure the obligation of the Company to make the Installment Payments and Purchase Price payments pursuant to, and as such terms are defined in, the Installment Payment and Bond Amortization Agreement, dated as of March 1, 1999 (hereinafter sometimes called the "1999A Brazos Agreement"), between the Brazos Authority and the Company. The maximum amount of bonds of the Ninety-eighth Series that may be issued is unlimited but the aggregate principal amount of bonds of the Ninety-eighth Series at any one time Outstanding shall not exceed $127,126,750. The maximum stated interest rate for any bonds of the Ninety-eighth Series shall not exceed 15% per annum. The Company shall receive a credit against its obligation to make any payment of the principal of and interest, if any, on any tranche of the bonds of the Ninety-eighth Series, whether at maturity, upon redemption or otherwise, in an amount equal to (x) the sum of (a) the amount, if any, on deposit in the Debt Service Fund maintained under the 1999A Brazos Bond Indenture which reduces the corresponding Installment Payment and (b) the amount, if any, paid by the Company pursuant to Section 5.04 of the 1999A Brazos Agreement in respect of the corresponding Installment Payment multiplied by (y) the ratio of the principal amount of Outstanding bonds of the Ninety-eighth Series to the principal amount 10 of outstanding Series 1999A Brazos Revenue Bonds, in each case immediately prior thereto. The Trustee may conclusively presume that the obligation of the Company to pay the principal of, and interest, if any, on any tranche of the bonds of the Ninety-eighth Series as the same shall become due and payable shall have been fully satisfied and discharged unless and until it shall have received a written notice from the trustee under the 1999A Brazos Bond Indenture, signed by the President, a Vice President or a Trust Officer of such trustee, stating that the corresponding Installment Payment or Purchase Price payment has become due and payable and has not been fully paid and specifying the amount of funds required to make such payment. (II) In the event that any Series 1999A Brazos Revenue Bonds outstanding under the 1999A Brazos Bond Indenture shall become immediately due and payable pursuant to Section 6.02 of the 1999A Brazos Bond Indenture, all bonds of the Ninety-eighth Series, then Outstanding, shall be redeemed by the Company, on the date such Series 1999A Brazos Revenue Bonds shall have become immediately due and payable, at the principal amount thereof. The Trustee may conclusively presume that no redemption of bonds of the Ninety-eighth Series is required pursuant to the first paragraph of this subsection (II) unless and until it shall have received a written notice from the trustee under the 1999A Brazos Bond Indenture, signed by the President, a Vice President or a Trust Officer of such trustee, stating that Series 1999A Brazos Revenue Bonds have become immediately due and payable pursuant to Section 6.02 of the 1999A Brazos Bond Indenture, and specifying the principal amount thereof. Said notice shall also contain a waiver of notice of such redemption by the trustee under the 1999A Brazos Bond Indenture, as the holder of all bonds of the Ninety-eighth Series then Outstanding. (III) The Company hereby waives its right to have any notice of redemption pursuant to subsection (II) of this Section 1 state that such notice is subject to the receipt of the redemption moneys by the Trustee on or before the date fixed for redemption. Notwithstanding the provisions of Section 12.02 of the Mortgage, any such notice under such subsection shall not be conditional. (IV) At the option of the registered owner, any bonds of the Ninety-eighth Series, upon surrender thereof for cancellation at the office or agency of the Company in the Borough of Manhattan, The City of New York, New York, shall be exchangeable for a like aggregate principal amount of bonds of the same series of other authorized denominations. Bonds of the Ninety-eighth Series shall not be transferable except to any successor trustee under the 1999A Brazos Bond Indenture, any such transfer to be made at the office or agency of the Company in the Borough of Manhattan, The City of New York, New York. 11 The Company hereby waives any right to make a charge for any exchange or transfer of bonds of the Ninety-eighth Series. ARTICLE II Miscellaneous Provisions SECTION 2. Subject to the amendments provided for in this Fifty-ninth Supplemental Indenture, the terms defined in the Original Indenture, as heretofore supplemented, shall for all purposes of this Fifty-ninth Supplemental Indenture have the meanings specified in the Original Indenture, as heretofore supplemented. SECTION 3. The Trustee hereby accepts the trusts herein declared, provided, created or supplemented and agrees to perform the same upon the terms and conditions herein and in the Original Indenture, as heretofore supplemented, set forth and upon the following terms and conditions: The Trustee shall not be responsible in any manner whatsoever for or in respect of the validity or sufficiency of this Fifty-ninth Supplemental Indenture or for or in respect of the recitals contained herein, all of which recitals are made by the Company solely. In general, each and every term and condition contained in Article XIX of the Original Indenture shall apply to and form part of this Fifty-ninth Supplemental Indenture with the same force and effect as if the same were herein set forth in full with such omissions, variations and insertions, if any, as may be appropriate to make the same conform to the provisions of this Fifty-ninth Supplemental Indenture. SECTION 4. Whenever in this Fifty-ninth Supplemental Indenture either of the parties hereto is named or referred to, this shall, subject to the provisions of Articles XVIII and XIX of the Original Indenture, be deemed to include the successors and assigns of such party, and all the covenants and agreements in this Fifty-ninth Supplemental Indenture contained, by or on behalf of the Company, or by or on behalf of the Trustee, shall, subject as aforesaid, bind and inure to the respective benefits of the respective successors and assigns of such parties, whether so expressed or not. SECTION 5. Nothing in this Fifty-ninth Supplemental Indenture expressed or implied, is intended, or shall be construed to confer upon, or to give to, any person, firm or corporation, other than the parties hereto and the holders of the bonds and coupons Outstanding under the Mortgage, any right, remedy or claim under or by reason of this Fifty-ninth Supplemental Indenture or any covenant, condition, stipulation, promise or agreement hereof, and all the covenants, conditions, stipulations, promises and agreements in this Fifty-ninth Supplemental Indenture contained, by or on behalf of the Company, shall be for the sole and exclusive benefit of the parties hereto, and of the holders of the bonds and coupons Outstanding under the Mortgage. 12 SECTION 6. This Fifty-ninth Supplemental Indenture shall be executed in several counterparts, each of which shall be an original and all of which shall constitute but one and the same instrument. 13 IN WITNESS WHEREOF, TEXAS UTILITIES ELECTRIC COMPANY has caused its corporate name to be hereunto affixed, and this instrument to be signed and sealed by its Chairman of the Board and Chief Executive, President or one of its Vice Presidents, and its corporate seal to be attested by its Secretary or one of its Assistant Secretaries for and in its behalf, and THE BANK OF NEW YORK has caused its corporate name to be hereunto affixed, and this instrument to be signed and sealed by one of its Vice Presidents or Assistant Vice Presidents and its corporate seal to be attested by one of its Assistant Vice Presidents, Assistant Secretaries or Assistant Treasurers, all as of the day and year first above written. TEXAS UTILITIES ELECTRIC COMPANY By /s/ John H. Carlson ------------------------------- JOHN H. CARLSON Vice President Attest: /s/ John F. Stephens, Jr. - ---------------------------------- JOHN F. STEPHENS, JR. Assistant Secretary Executed, sealed and delivered by TEXAS UTILITIES ELECTRIC COMPANY in the presence of: /s/ Justin B. Rhodes - ---------------------------------- /s/ Craig Taylor - ---------------------------------- 14 THE BANK OF NEW YORK, Trustee By /s/ W.N. Gitlin ----------------------------- W. N. GITLIN Vice President Attest: /s/ Remo J. Reale - ---------------------------------- REMO J. REALE Assistant Vice President Executed, sealed and delivered by THE BANK OF NEW YORK in the presence of: /s/ Mary LaGumina - ---------------------------------- /s/ Thomas B. Zakrzewski - ---------------------------------- 15 STATE OF TEXAS ...............) ) SS.: COUNTY OF DALLAS..............) Before me, a Notary Public in and for said State, on this day personally appeared JOHN H. CARLSON, known to me to be the person whose name is subscribed to the foregoing instrument and known to me to be a Vice President of TEXAS UTILITIES ELECTRIC COMPANY, a Texas corporation, and acknowledged to me that said person executed said instrument for the purposes and consideration therein expressed, and as the act of said corporation. Given under my hand and seal of office this 22nd day of March, 1999. /s/ Julia Laxson ---------------------------------- JULIA LAXSON Notary Public, State of Texas My Commission Expires February 26, 2001 16 STATE OF NEW YORK ) ) SS.: COUNTY OF NEW YORK ) Before me, a Notary Public in and for said State, on this day personally appeared W.N. GITLIN, known to me to be the person whose name is subscribed to the foregoing instrument and known to me to be a Vice President of THE BANK OF NEW YORK, a New York corporation, and acknowledged to me that said person executed said instrument for the purposes and consideration therein expressed, and as the act of said corporation. Given under my hand and seal of office this 30th day of March, 1999. /s/ William J. Cassels -------------------------------- WILLIAM J. CASSELS Notary Public, State of New York No. 01CA5027729 Qualified in Bronx County Certificate filed in New York County Commission Expires May 16, 2000