Exhibit 10.1

Supplemental Indenture

SUPPLEMENTAL INDENTURE dated as of December 30, 2005 (this “Supplemental
Indenture”) among NRG Energy, Inc., a Delaware corporation (the “Company”), the
subsidiaries of the Company set forth on Schedule A hereto, as guarantors (the
“Guarantors”), and Law Debenture Trust Company of New York, as trustee under the
Indenture referred to below (the “Trustee”).

W I T N E S S E T H :

WHEREAS, the Company, the Guarantors and the Trustee heretofore executed and
delivered an Indenture, dated as of December 23, 2003 (the “Indenture”),
providing for the issuance of the 8% Second Priority Senior Secured Notes due
2013 (the “Notes”) (capitalized terms used herein but not otherwise defined have
the meanings ascribed thereto in the Indenture);

WHEREAS, Section 9.02 of the Indenture provides that the Company and the
Trustee, with the written consent of the Holders of at least a majority in
principal amount of the Notes outstanding, may amend or waive certain terms and
covenants in the Indenture as described below;

WHEREAS, the Holders of a majority in principal amount of the Notes outstanding
have consented to the waiver and amendments effected by this Supplemental
Indenture;

WHEREAS, the Company and each of the Subsidiary Guarantors are undertaking to
execute and deliver this Supplemental Indenture to amend certain terms and
covenants in the Indenture in connection with the Offer to Purchase and Consent
Solicitation Statement of the Company, dated as of December 15, 2005, and any
amendments, modifications or supplements thereto (the “Tender Offer and
Solicitation”); and

WHEREAS, this Supplemental Indenture has been duly authorized by all necessary
corporate action on the part of the Company and each of the Subsidiary
Guarantors.

NOW, THEREFORE, in consideration for the premises and for other good and
valuable consideration, the receipt of which is hereby acknowledged, the
Company, each of the Subsidiary Guarantors and the Trustee mutually covenant and
agree for the equal and ratable benefit of the Holders as follows:

ARTICLE I

AMENDMENTS AND WAIVERS

Section 1.1 Applicability of Certain Indenture Provisions to the Tender Offer
and Solicitation. The application of the provisions of Article 4 of the
Indenture are hereby waived to the extent that such provisions might otherwise
prohibit the Escrow Financing (as defined in the Tender Offer and Solicitation),
including the proceeds of any notes offering in connection with the Acquisition
(as defined in the Tender Offer and Solicitation) being placed into an escrow
account pursuant to an escrow and security agreement.

Section 1.2 Amendments to the Indenture. Effective at the time of payment or
deposit with DTC (the “Payment Date”) of an amount of money sufficient to pay
for all Notes validly tendered and accepted pursuant to the Tender Offer and
Solicitation and to make all consent payments required under the Tender Offer
and Solicitation:

  (i)   The Indenture is hereby amended to delete Section 4.02 (Maintenance of
Office or Agency), Section 4.03 (Reports), Section 4.04 (Compliance
Certificate), Section 4.05 (Taxes), Section 4.06 (Stay, Extension and Usury
Laws), Section 4.07 (Restricted Payments), Section 4.08 (Dividend and Other
Payment Restrictions Affecting Subsidiaries), Section 4.09 (Incurrence of
Indebtedness and Issuance of Preferred Stock), Section 4.10 (Asset Sales),
Section 4.11 (Transactions with Affiliates), Section 4.12 (Liens), Section 4.13
(Business Activities), Section 4.14 (Corporate Existence), Section 4.15 (Offer
to Repurchase Upon Change of Control), Section 4.16 (Limitation on Sale and
Leaseback Transactions), Section 4.18 (Additional Subsidiary Guarantees),
Section 4.19 (Designation of Restricted and Unrestricted Subsidiaries),
Section 4.20 (Changes in Covenant When Notes Rated Investment Grade),
Section 5.01 (Merger, Consolidation, or Sale of Assets) and Section 5.02
(Successor Corporation Substituted) in their entirety and all references thereto
contained elsewhere in the Indenture in their entirety;

  (ii)   The failure to comply with the terms of any of the foregoing Sections
of the Indenture shall no longer constitute a Default or an Event of Default
under the Indenture and shall no longer have any other consequence under the
Indenture;

  (iii)   The Indenture is hereby amended to delete clauses (3), (4), (5), (6),
(7), (8), (9) and (10) of Section 6.01 in their entirety and all references
thereto contained in Section 6.01 and elsewhere in the Indenture in their
entirety, and the occurrence of the events described in clauses (3), (4), (5),
(6), (7), (8), (9) and (10) of Section 6.01 shall no longer constitute Events of
Default;

  (iv)   All definitions set forth in Section 1.01 of the Indenture that relate
to defined terms used solely in sections deleted by this Supplemental Indenture
are hereby deleted in their entirety; and

  (v)   All references to Section 6.01 of the Indenture shall mean Section 6.01
as amended by this Supplemental Indenture.

ARTICLE II

MISCELLANEOUS

Section 2.1 Effect of Supplemental Indenture. Upon the execution and delivery of
this Supplemental Indenture by the Company, each of the Subsidiary Guarantors
and the Trustee, the Indenture shall be supplemented in accordance herewith, and
this Supplemental Indenture shall form a part of the Indenture for all purposes,
and every Holder of Notes heretofore or hereafter authenticated and delivered
under the Indenture shall be bound hereby; provided, that the amendments to the
Indenture set forth in Section 1.2 of this Supplemental Indenture shall become
operative as specified in Section 1.2 hereof. Prior to the Payment Date, the
Company may terminate this Supplemental Indenture upon written notice to the
Trustee.

Section 2.2 Indenture Remains in Full Force and Effect. Except as supplemented
hereby, all provisions in the Indenture shall remain in full force and effect.

Section 2.3 Indenture and Supplemental Indenture Construed Together. This
Supplemental Indenture is an indenture supplemental to and in implementation of
the Indenture, and the Indenture and this Supplemental Indenture shall
henceforth be read and construed together.

Section 2.4 Confirmation and Preservation of Indenture. The Indenture as
supplemented by this Supplemental Indenture is in all respects confirmed and
preserved.

Section 2.5 Conflict with the Trust Indenture Act. If any provision of this
Supplemental Indenture limits, qualifies or conflicts with any provision of the
TIA that is required under the TIA to be a part of and govern any provision of
this Supplemental Indenture, the provision of the TIA shall control. If any
provision of this Supplemental Indenture modifies or excludes any provision of
the TIA that may be so modified or excluded, the provision of the TIA shall be
deemed to apply to the Indenture as so modified or to be excluded by this
Supplemental Indenture, as the case may be.

Section 2.6 Severability. 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.

Section 2.7 Benefits of Supplemental Indenture. Nothing in this Supplemental
Indenture or the Notes, express or implied, shall give to any Person, other than
the parties hereto and thereto and their successors hereunder and thereunder and
the Holders of the Notes, any benefit of any legal or equitable right, remedy or
claim under the Indenture, this Supplemental Indenture or the Notes.

Section 2.8 Successors. All agreements of the Company and each of the Subsidiary
Guarantors in this Supplemental Indenture shall bind their respective
successors. All agreements of the Trustee in this Supplemental Indenture shall
bind its successors.

Section 2.9 Acceptance by Trustee. The Trustee accepts the amendments to the
Indenture effected by this Supplemental Indenture and agrees to execute the
trusts created by the Indenture as hereby amended, but only upon the terms and
conditions set forth in the Indenture.

Section 2.10 Certain Duties and Responsibilities of the Trustee. In entering
into this Supplemental Indenture, the Trustee shall be entitled to the benefit
of every provision of the Indenture and the Notes relating to the conduct or
affecting the liability or affording protection to the Trustee, whether or not
elsewhere herein so provided.

Section 2.11 Governing Law. This Supplemental Indenture shall be governed by,
and construed in accordance with, the laws of the State of New York but without
giving effect to applicable principles of conflicts of law to the extent that
the application of the laws of another jurisdiction would be required thereby.

Section 2.12 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.

Section 2.13 Headings. The Article and Section headings herein are inserted for
convenience of reference only, are not intended to be considered a part hereof
and shall not modify or restrict any of the terms or provisions hereof.

Section 2.14 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 are made by the
Company and each of the Subsidiary Guarantors.

* * * * *

1

IN WITNESS WHEREOF, the parties hereto have caused this Supplemental Indenture
to be duly executed as of the date first written above.

NRG ENERGY, INC.

By: /s/ Robert C. Flexon
Name: Robert C. Flexon
Title: Chief Financial Officer

GUARANTORS:

ARTHUR KILL POWER LLC

ASTORIA GAS TURBINE POWER LLC
BERRIANS I GAS TURBINE POWER LLC
BIG CAJUN II UNIT 4 LLC
CAPISTRANO COGENERATION COMPANY
CHICKAHOMINY RIVER ENERGY CORP.
COMMONWEALTH ATLANTIC POWER LLC
CONEMAUGH POWER LLC
CONNECTICUT JET POWER LLC
DEVON POWER LLC
DUNKIRK POWER LLC
EASTERN SIERRA ENERGY COMPANY
EL SEGUNDO POWER II LLC
HANOVER ENERGY COMPANY
HUNTLEY POWER LLC
INDIAN RIVER OPERATIONS INC.
INDIAN RIVER POWER LLC
JAMES RIVER POWER LLC
KAUFMAN COGEN LP
KEYSTONE POWER LLC
LOUISIANA GENERATING LLC
MIDDLETOWN POWER LLC
MONTVILLE POWER LLC
NEO CALIFORNIA POWER LLC
NEO CHESTER-GEN LLC
NEO CORPORATION
NEO FREEHOLD-GEN LLC
NEO LANDFILL GAS HOLDINGS INC.
NEO POWER SERVICES INC.
NORWALK POWER LLC
NRG AFFILIATE SERVICES INC.
NRG ARTHUR KILL OPERATIONS INC.
NRG ASIA-PACIFIC, LTD.
NRG ASTORIA GAS TURBINE OPERATIONS, INC.
NRG BAYOU COVE LLC
NRG CABRILLO POWER OPERATIONS INC.
NRG CADILLAC OPERATIONS INC.
NRG CALIFORNIA PEAKER OPERATIONS LLC
NRG CONNECTICUT AFFILIATE SERVICES INC.
NRG DEVON OPERATIONS INC.
NRG DUNKIRK OPERATIONS INC.
NRG EL SEGUNDO OPERATIONS INC.
NRG HUNTLEY OPERATIONS INC.
NRG INTERNATIONAL LLC
NRG KAUFMAN LLC
NRG MESQUITE LLC
NRG MIDATLANTIC AFFILIATE SERVICES INC.
NRG MIDATLANTIC GENERATING LLC
NRG MIDDLETOWN OPERATIONS INC.
NRG MONTVILLE OPERATIONS INC.
NRG NEW JERSEY ENERGY SALES LLC
NRG NEW ROADS HOLDINGS LLC
NRG NORTH CENTRAL OPERATIONS INC.
NRG NORTHEAST AFFILIATE SERVICES INC.
NRG NORTHEAST GENERATING LLC
NRG NORWALK HARBOR OPERATIONS INC.
NRG OPERATING SERVICES, INC.
NRG OSWEGO HARBOR POWER OPERATIONS INC.
NRG POWER MARKETING INC.
NRG ROCKY ROAD LLC
NRG SAGUARO OPERATIONS INC.
NRG SOUTH CENTRAL AFFILIATE SERVICES INC.
NRG SOUTH CENTRAL GENERATING LLC
NRG SOUTH CENTRAL OPERATIONS INC.
NRG WEST COAST LLC
NRG WESTERN AFFILIATE SERVICES INC.
OSWEGO HARBOR POWER LLC
SAGUARO POWER LLC
SOMERSET OPERATIONS INC.
SOMERSET POWER LLC
VIENNA OPERATIONS INC.
VIENNA POWER LLC

By: /s/ George P. Schaefer
Name: George P. Schaefer
Title: Authorized Signatory

LAW DEBENTURE TRUST COMPANY OF NEW YORK

By: /s/ Daniel R. Fisher
Name: Daniel R. Fisher
Title: Senior Vice President

2

SCHEDULE A

SCHEDULE OF GUARANTORS

 
 
Arthur Kill Power LLC
 
Astoria Gas Turbine Power LLC
 
Berrians I Gas Turbine Power LLC
 
Big Cajun II Unit 4 LLC
 
Capistrano Cogeneration Company
 
Chickahominy River Energy Corp.
 
Commonwealth Atlantic Power LLC
 
Conemaugh Power LLC
 
Connecticut Jet Power LLC
 
Devon Power LLC
 
Dunkirk Power LLC
 
Eastern Sierra Energy Company
 
El Segundo Power II LLC
 
Hanover Energy Company
 
Huntley Power LLC
 
Indian River Operations Inc.
 
Indian River Power LLC
 
James River Power LLC
 
Kaufman Cogen LP
 
Keystone Power LLC
 
Louisiana Generating LLC
 
Middletown Power LLC
 
Montville Power LLC
 
NEO California Power LLC
 
NEO Chester-Gen LLC
 
NEO Corporation
 
NEO Freehold-Gen LLC
 
NEO Landfill Gas Holdings Inc.
 
NEO Power Services Inc.
 
Norwalk Power LLC
 
NRG Affiliate Services Inc.
 
NRG Arthur Kill Operations Inc.
 
NRG Asia-Pacific, Ltd.
 
NRG Astoria Gas Turbine Operations, Inc.
 
NRG Bayou Cove LLC
 
NRG Cabrillo Power Operations Inc.
 
NRG Cadillac Operations Inc.
 
NRG California Peaker Operations LLC
 
NRG Connecticut Affiliate Services Inc.
 
NRG Devon Operations Inc.
 
NRG Dunkirk Operations Inc.
 
NRG El Segundo Operations Inc.
 
NRG Huntley Operations Inc.
 
NRG International LLC
 
NRG Kaufman LLC
 
NRG Mesquite LLC
 
NRG MidAtlantic Affiliate Services Inc.
 
NRG MidAtlantic Generating LLC
 
NRG Middletown Operations Inc.
 
NRG Montville Operations Inc.
 
NRG New Jersey Energy Sales LLC
 
NRG New Roads Holdings LLC
 
NRG North Central Operations Inc.
 
NRG Northeast Affiliate Services Inc.
 
NRG Northeast Generating LLC
 
NRG Norwalk Harbor Operations Inc.
 
NRG Operating Services, Inc.
 
NRG Oswego Harbor Power Operations Inc.
 
NRG Power Marketing Inc.
 
NRG Rocky Road LLC
 
NRG Saguaro Operations Inc.
 
NRG South Central Affiliate Services Inc.
 
NRG South Central Generating LLC
 
NRG South Central Operations Inc.
 
NRG West Coast LLC
 
NRG Western Affiliate Services Inc.
 
Oswego Harbor Power LLC
 
Saguaro Power LLC
 
Somerset Operations Inc.
 
Somerset Power LLC
 
Vienna Operations Inc.
 
Vienna Power LLC
 

3