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Exhibit 10.50
 LOAN AGREEMENT
 DATED AS OF JULY 26, 2007
 between
 RIO VISTA ENERGY PARTNERS L.P.
as Borrower,
 and
 RZB FINANCE LLC
as Lender




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LOAN AGREEMENT
   Section 1
     subsection 1.2
      - 2 -




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subsection
2.1(A)
       - 3 -




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Section 3
  Exhibit A
  subsection
2.2(A)(2)
       subsection 7.1
   - 4 -




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subsection 2.2(B)
 subsection 2.2(A)
  - 5 -




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per annum
 subsection 2.1(A)
       - 6 -




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provided
  - 7 -




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subsection 2.1(B)
 subsection
2.2(E)
     provided
     - 8 -




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provided subsection 6.1 Schedule 1.1(A) subsection 7.1(I) provided however provided
further however provided however provided
further however
      - 9 -




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Schedule 6.4
    subsection 5.1(C)
     - 10 -




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Accounting Terms subsection 5.1
  - 11 -




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Other Definitional Provisions Section
1.1
 The Loans
 The Loan
 Loan
 Notes subsection 8.1
 Evidence of Loan Obligations
  - 12 -




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Interest
 Rate of Interest subsection 2.1(A)
  Interest Periods provided
   provided
    - 13 -




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Computation and Payment of Interest provided
  Interest Laws
  - 14 -




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Continuation subsection 2.2(A)(2)
  subsection 2.2(E)
  subsection 2.2(E)
 Fees
 Closing Fee
 Fees Non-Refundable subsection 2.3(A)
  - 15 -




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Payments and Prepayments
 Manner and Time of Payment
 
 Repayments BORROWER EXPRESSLY ACCEPTS THE RISK OF
BORROWING A LOAN PAYABLE ON DEMAND AND THAT LENDER MAY DEMAND PAYMENT AT ANY TIME IN ITS SOLE
DISCRETION WHETHER OR NOT ANY DEFAULT OR EVENT OF DEFAULT HAS OCCURRED, AND THAT LENDER SHALL HAVE
NO EXPRESS OR IMPLIED DUTY OF GOOD FAITH OR FAIR DEALING, DUTY TO ACT IN A COMMERCIALLY REASONABLE
MANNER (EXCEPT WITH RESPECT TO DISPOSITION OF COLLATERAL TO THE EXTENT REQUIRED BY LAW), OR OTHER
IMPLIED DUTY OR FIDUCIARY DUTY. IN ADDITION, BORROWER ACKNOWLEDGES THAT IN THE EVENT OF ANY DEMAND
BY LENDER AT ANY TIME OR NON PAYMENT BY BORROWER ON THE MATURITY DATE, IT MAY LOSE THE EQUITY IT
INVESTED IN THE MERGER. BORROWER DECIDED TO PROCEED ON A DEMAND LOAN BASIS FOR ITS OWN BUSINESS
REASONS INCLUDING, WITHOUT LIMITATION, BORROWERS DETERMINATION THAT IT MUST CONSUMMATE THE MERGER
QUICKLY.
 Mandatory Prepayments
 Voluntary Prepayments
 Terms Applicable to Prepayments subsection 2.4 subsection
2.8 subsection 2.4
  - 16 -




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Payments on Business Days
 Capital Adequacy and Other Adjustments
  - 17 -




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Taxes, etc
 No Deductions
 Changes in Laws
   subsection 2.6(B)
  - 18 -




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Required Termination and Prepayment subsection 2.7 subsection 2.8
  Compensation subsection 2.7
 Booking of the Loan
 Assumptions Concerning Funding of LIBOR Loans subsection 2.8 provided however subsection 2.8
  - 19 -




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CONDITIONS TO LOANS, ETC.
 Conditions to Loans, etc
 Closing Deliveries Schedule 3.1(A)
 Representations and Warranties
 No Default
 Performance of Agreements
 No Prohibition
 No Litigation
   - 20 -




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REPRESENTATIONS AND WARRANTIES
  Organization, Powers, Capitalization
 Organization and Powers
 Capitalization Schedule 4.1(B) Schedule 4.1(B) provided Schedule
4.1(B)
  - 21 -




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Authorization of Borrowing, No Conflict Schedule 4.2
 Financial Condition
   - 22 -




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Indebtedness and Liabilities
 The Merger
  - 23 -




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Intangible Assets
 Title to Properties; Liens subsection 6.3(B)
 Litigation; Adverse Facts Schedule 4.8
 Payment of Taxes Schedule 4.9 subsection 5.5
  - 24 -




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Performance of Agreements
 Employee Benefit Plans; Labor Disputes ,
  Environmental Compliance
  - 25 -




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Solvency
 Disclosure
 Compliance with Laws
 Subsidiaries Schedule 4.1(B)
 No Default
  - 26 -




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Name Changes, Mergers, Acquisitions
 Governmental Regulation
 AFFIRMATIVE COVENANTS
 , Section 5
 Financial Statements and Other Reports
 Year-End Financials
 Quarterly Financials
  - 27 -




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Projections
 Reports
 Compliance Certificate subsection 5.1
 Government Notices
 Events of Default, etc.
 Litigation
  - 28 -




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Other Information
 Access to Accountants and Management
 Inspection provided
 Existence ,
 Payment of Taxes , provided however
 Maintenance of Properties; Insurance
  - 29 -




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Compliance with Laws
 Further Assurances ,
 Use of Proceeds and Margin Security
 Merger Agreement Notices
 Merger Agreement
 Net Worth
  - 30 -




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Post-Closing provided
  NEGATIVE COVENANTS
 s
 Indebtedness and Liabilities
 Guaranties
  - 31 -




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Transfers, Liens and Related Matters
 Transfers subsection
2.4(C))
 Liens
 Investments and Loans
 Restricted Junior Payments
 Restriction on Fundamental Changes
    - 32 -




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Transactions with Affiliates
 Environmental Liabilities
 Conduct of Business
 Compliance with ERISA
 Subsidiaries
 Amendments
  - 33 -




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DEFAULT, RIGHTS AND REMEDIES
 Event of Default
 Payment
 Default in Other Agreements
 Breach of Certain Provisions subsections 5.1, 5.3, 5.4, 5.5, 5.6(A) or 5.12 or Section
6
 Breach of Warranty
 Other Defaults Under Loan Documents subsection 7.1
 Change in Control
  - 34 -




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Involuntary Bankruptcy; Appointment of Receiver, etc.
 Voluntary Bankruptcy; Appointment of Receiver, etc. subsection 7.1(H)
 Judgment and Attachments
 Dissolution
 Solvency subsection 4.13
 Injunction
  - 35 -




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Invalidity of any Loan Documents
 Licenses and Permits
 Security Documents
 Material Adverse Change
 Acceleration subsections 7.1(G) or 7.1(H)
 ASSIGNMENT AND PARTICIPATION
 Assignments and Participations in Loans
 subsection 8.1
  - 36 -




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provided provided further subsections 2.5, 2.6, 2.8, 8.2, 9.1 and 9.2
  Disclosing Party Regulatory Authority provided Non-Disclosing Party
   - 37 -




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Transactions
  Set Off and Sharing of Payments
 MISCELLANEOUS
 Expenses and Attorneys Fees
  - 38 -




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Indemnity subsection
9.1 provided
 Amendments and Waivers
    Notices
  - 39 -




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If to Borrower:
    
    Rio Vista Energy Partners L.P.77-530 Enfield Lane, Bldg. DPalm Desert, California 92211Attn: Ian BothwellTelecopy No. (310) 563-6255If to Lender:
    
    RZB Finance LLC1133 Avenue of the AmericasNew York, NY 10036Attn: Ms. Nancy ReminiTelecopy No.: (212) 944-6389
 subsection 9.4
 Survival of Warranties and Certain Agreements subsections 2.5, 2.6, 2.8, 8.2, 9.1 and
9.2
 Indulgence Not Waiver
 Marshaling; Payments Set Aside
  - 40 -




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ENTIRE AGREEMENT
 Independence of Covenants
 Severability
 Headings
 APPLICABLE LAW .
 Successors and Assigns
 No Fiduciary Relationship; Limitation of Liabilities
   - 41 -




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CONSENT TO JURISDICTION FORUM NON CONVENIENS .
 WAIVER OF JURY TRIAL
 Construction
  - 42 -




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Counterparts; Effectiveness
 No Duty
 Patriot Act
   - 43 -




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RIO VISTA ENERGY PARTNERS L.P., as BorrowerBy:
    
    Rio Vista GP LLC, as its General PartnerBy:
    
    /s/ Ian BothwellName:
    
    Ian BothwellTitle:
    
    Acting Chief Executive OfficerRZB FINANCE LLC, as LenderBy:
    
    /s/ Nancy ReminiName:
    
    Nancy ReminiTitle:
    
    Vice PresidentBy:
    
    /s/ Pearl GeffersName:
    
    Pearl GeffersTitle:
    
    First Vice President




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EXHIBITS
 A.
    
    Compliance Certificate




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SCHEDULES
 3.1(A)
    
    List of Closing Documents4.1(B)
    
    Capitalization of Loan Parties4.2
    
    Consents4.3
    
    Financial Condition4.4
    
    Indebtedness4.5
    
    Merger Exceptions4.6
    
    Intellectual Property4.7
    
    Title to Properties4.8
    
    Litigation4.9
    
    Taxes; Audits4.12
    
    Environmental Matters4.14
    
    Disclosure4.15
    
    Compliance with Laws4.18
    
    Name Changes, Mergers, Acquisitions5.13
    
    Lease Provisions6.4
    
    Permitted Investments6.6
    
    Permitted Acquisition / Merger




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SCHEDULE 3.1(A)
     1.
    
    Loan Agreement
 (a)
    
    Exhibits(b)
    
    Schedules
 2.
    
    (a) Guaranty by POC
 (b)
    
    Guaranty by RVOP(c)
    
    Guaranty by Merger Sub(d)
    
    Confirmation by Borrower, POC and RVOP that existing security
agreements secure new guaranties and, in the case of Borrower, the new Loan(e)
    
    Promissory Note
 3.
    
    (a) Assignment of Merger Agreement by Borrower and Merger Sub
 (b)
    
    Consent by Sellers(c)
    
    Security Questionnaire as to Sellers [WAIVED](d)
    
    UCC Search against Sellers(e)
    
    Certification by Borrower as to true and complete copy of merger documents
 4.
    
    (a) Security Agreement by Merger Sub
 (b)
    
    UCC filing against Merger Sub and Target(c)
    
    Lien search against Merger Sub
 (i)
    
    State of incorporation
 (d)
    
    Lien search against Regional Enterprizes, Inc.
 (i)
    
    State of incorporation
 (e)
    
    Security Questionnaire as to Merger Sub and Regional Enterprizes, Inc.(f)
    
    Certificates of title for vehicles [POST-CLOSING](g)
    
    Pledge Agreement by Borrower of 100% of capital stock of Merger Sub(h)
    
    Stock Power endorsed in blank (undated)(i)
    
    Stock Certificates representing the pledged shares(j)
    
    Letter from Merger Sub acknowledging Pledge
 5.
    
    (a) Deed of Trust with respect to Virginia Property
 (b)
    
    UCC fixture filing with respect to Virginia Property(c)
    
    Assignment of Leases with respect to Virginia Property(d)
    
    Environment Indemnity with respect to Virginia Property
  - 47 -




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6.
    

(i)      mortgagee title insurance policies and endorsements, issued by such title insurance
companies, in such amounts with only such exceptions, all as shall be required by and
satisfactory to Lender,
 (ii)
    
    copies of all encumbrances affecting title and leases affecting premises(iii)
    
    affidavits delivered to the title company (if any),(iv)
    
    certificates of occupancy,(v)
    
    evidence of payment of (A) recording taxes, and (B) title company
charges,(vi)
    
    receipt and recording instructions for documents delivered to title company,(vii)
    
    letter to title company with recording instructions,(viii)
    
    ALTA as-built surveys in form and substance satisfactory to and certified to
Lender,(ix)
    
    letter from building department regarding zoning,(x)
    
    evidence of availability of all utilities and access to roads/water,(xi)
    
    flood hazard certification from surveyor,(xii)
    
    estoppel certificates from ground lessor,(xiii)
    
    subordination agreements for recording in real estate records.
 7.
    
    Corporate or partnership organizational and authorization documents with respect to:
 (a)
    
    Borrower(b)
    
    Guarantors
 8.
    
    Letter of direction as to disbursement of Loan Proceeds and balance of merger purchase price
(which Borrower shall have deposited with Lender)9.
    
    Opinion of Borrowers counsel as to such matters as the Lender may request, including,
without limitation, the consummation of the Merger and the filing of the Articles of Merger with
all necessary governmental authorities10.
    
    (a) Evidence of the disbursement of Intercompany Loan to Merger Sub
 (b)
    
    Original promissory note evidencing Intercompany Loan, endorsed to the order of Lender
 11.
    
    Copies of consents and approvals of governmental authorities relating to Merger12.
    
    Copies of insurance policies, insurance certificate and endorsements with respect to
Borrower and Guarantors:
 (a)
    
    casualty(b)
    
    liability(c)
    
    business interruption(d)
    
    environmental(e)
    
    earthquake(f)
    
    terminal operators policy
  - 48 -




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13.
    
    Certificate of Borrower as to
 (a)
    
    Compliance(b)
    
    Solvency(c)
    
    Projections(d)
    
    Pro Forma(e)
    
    Environmental Reports
 14.
    
    Payment of closing fee15.
    
    Evidence of capital contribution16.
    
    Patents, trademarks [Waived]17.
    
    First Amendment to POC Line Letter to reduce facility by amount outstanding to Borrower
under new Loan.18.
    
    Appraisal of fixed assets / real property19.
    
    True and complete copies of the following, each certified as such in a certificate
executed by the president or chief financial officer of Borrower:
 (i)
    
    the Agreement and Plan of Merger;(ii)
    
    Executed Articles of Merger filed with Virginia State Corporation Commission on the
Closing Date and such other evidence of consummation of the Merger as the Lender may request(iii)
    
    environmental audit reports prepared by Delta Environmental
Consultants, Inc. and U.N.I. Engineering, Inc. covering all properties owned by
Regional Enterprizes, Inc. including reliance letters addressed to Lender; and(iv)
    
    all press releases issued by the Sellers (to the extent
available to Borrower or the Guarantors), Borrower or any other Loan Party with
respect to the Merger and related transactions.
 20.
    
    All opinions and certificates issued by Sellers and Target and their counsel pursuant
to the Merger Agreement, together with letters authorizing Lender to rely thereon as if
addressed to Lender.21.
    
    Such other documents, agreements and instruments as Lender may reasonable request.
  - 49 -




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SCHEDULE 5.13
 LEASE PROVISIONS
  Leasehold Mortgages and Related Matters.
       - 50 -




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- 51 -




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- 52 -




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- 53 -




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both and
  - 54 -