GUARANTY

Exhibit 10.70

GUARANTY

THIS GUARANTY is made as of November 19, 2007 by each party named on the signature pages hereto and the Additional Guarantors (as hereinafter defined) (such Persons so listed and the Additional Guarantors individually and collectively herein called “ Guarantor ”) in favor of TCW ASSET MANAGEMENT COMPANY, as administrative agent for Holders, as such term is defined in the Note Purchase Agreement described below.

RECITALS:

1. Rio Vista Penny LLC, an Oklahoma limited liability company ( “Company ”), has executed in favor of Holders those certain promissory notes dated of even date herewith, payable to the order of Holders in the aggregate principal amount of $30,000,000 (such promissory notes, as from time to time amended, and all promissory notes given in substitution, renewal or extension therefor or thereof, in whole or in part, being herein collectively called the “Notes ”).

2. The Notes were executed pursuant to a Note Purchase Agreement dated of even date herewith (herein, as from time to time amended, supplemented or restated, called the “ Note Purchase Agreement ”), by and among Company, Agent and Holders, pursuant to which Holders have agreed to advance funds to Company under the Notes.

3. It is a condition precedent to Holders’ obligations to advance funds pursuant to the Note Purchase Agreement that Guarantor shall execute and deliver to Agent a satisfactory guaranty of Company’s obligations under the Notes and the Note Purchase Agreement.

4. Rio Vista ECO LLC, an Oklahoma limited liability company (“ ECO ”), owns all of the outstanding equity interests of Company and GO (as each are defined below).

5. Rio Vista GO LLC, an Oklahoma limited liability company (“ GO ”), has executed in favor of Company that certain promissory note dated as of November 19, 2007, payable to the order of Company in the aggregate principal amount of $2,200,000 (such promissory note, as from time to time amended, and all promissory notes given in substitution, renewal or extension therefor or thereof, in whole or in part, being herein collectively called the “ GO Note ”).

6. As part of the consideration of Company’s advancing funds under the GO Note to GO, GO agreed to execute and deliver to Agent a satisfactory guaranty of Company’s obligations under the Notes and the Note Purchase Agreement.

7. GO owns all of the outstanding equity interests of GO, LLC, an Oklahoma limited liability company (“ GO LLC ”).

8. Company owns all of the outstanding equity interests of MV Pipeline Company, an Oklahoma corporation (“ MV ”).

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9. Company, ECO, GO, GO LLC, MV, and the other direct and indirect subsidiaries of Company are mutually dependent on each other in the conduct of their respective businesses under a holding company structure, with the credit needed from time to time by each often being provided by another or by means of financing obtained by one such affiliate with the support of the others for their mutual benefit and the ability of each to obtain such financing being dependent on the successful operations of the others.

10. Each Guarantor has determined that such Guarantor’s execution, delivery and performance of this Guaranty may reasonably be expected to benefit such Guarantor, directly or indirectly, and are in the best interests of such Guarantor.

NOW, THEREFORE, in consideration of the premises, of the benefits which will inure to each Guarantor from Holders’ advances of funds to Company under the Note Purchase Agreement, and of Ten Dollars and other good and valuable consideration, the receipt and sufficiency of all of which are hereby acknowledged, and in order to induce Holders to advance funds under the Note Purchase Agreement, each Guarantor hereby agrees with Agent, for the benefit of Agent and Holders as follows:

AGREEMENTS:

Section 1. Definitions . Reference is hereby made to the Note Purchase Agreement for all purposes. All terms used in this Guaranty which are defined in the Note Purchase Agreement and not otherwise defined herein shall have the same meanings when used herein. All references herein to any Obligation Document, Note Document, or other document or instrument refer to the same as from time to time amended, supplemented or restated. As used herein the following terms shall have the following meanings:

“ Additional Guarantor ” has the meaning given to such term in Section 11.

“ Agent ” means the Person who, at the time in question, is the “Administrative Agent” under the Note Purchase Agreement.

“ Holders ” means all who at any time are “Holders” under the Note Purchase Agreement.

“ Obligations ” means collectively all of the indebtedness, obligations, and undertakings which are guaranteed by each Guarantor and described in subsections (a) and (b) of Section 2.

“ Obligation Documents ” means this Guaranty, the Notes, the Note Purchase Agreement, the Note Documents, all other documents and instruments under, by reason of which, or pursuant to which any or all of the Obligations are evidenced, governed, secured, or otherwise dealt with, and all other documents, instruments, agreements, certificates, legal opinions and other writings heretofore or hereafter delivered in connection herewith or therewith.

“ Obligors ” means Company, Guarantors and any other endorsers, guarantors or obligors, primary or secondary, of any or all of the Obligations.

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“ Security ” means any rights, properties, or interests of Agent or Holders, under the Obligation Documents or otherwise, which provide recourse or other benefits to Agent or Holders in connection with the Obligations or the non-payment or non-performance thereof, including collateral (whether real or personal, tangible or intangible) in which Agent or Holders have rights under or pursuant to any Obligation Documents, guaranties of the payment or performance of any Obligation, bonds, surety agreements, keep-well agreements, letters of credit, rights of subrogation, rights of offset, and rights pursuant to which other claims are subordinated to the Obligations.

Section 2. Guaranty .

(a) Each Guarantor hereby irrevocably, absolutely, and unconditionally guarantees to Agent and each Holder the prompt, complete, and full payment when due, and no matter how the same shall become due, of:

(i) the Notes, including all principal, all interest thereon and all other sums payable thereunder;

(ii) all obligations or liabilities of any Obligor owing to Administrative Agent or any Holder Party under the Security Documents;

(iii) all other sums payable under the other Note Documents, whether for principal, interest, fees or otherwise; and

(iv) any and all other indebtedness or liabilities which may at any time be owed to any Holder Party, whether incurred heretofore or hereafter or concurrently herewith, voluntarily or involuntarily, whether owed alone or with others, whether fixed, contingent, absolute, inchoate, liquidated or unliquidated, whether such liability arises by notes, discounts, overdrafts, open account indebtedness or in any other manner whatsoever, and including interest, attorneys’ fees and collection costs as may be provided by law or in any instrument or agreement evidencing any such indebtedness or liability.

Without limiting the generality of the foregoing, each Guarantor’s liability hereunder shall extend to and include all post-petition interest, expenses, and other duties and liabilities of Company described above in this subsection (a), or below in the following subsection (b), which would be owed by Company but for the fact that they are unenforceable or not allowable due to the existence of a bankruptcy, reorganization, or similar proceeding involving Company.

(b) Each Guarantor hereby irrevocably, absolutely, and unconditionally guarantees to Agent and each Holder the prompt, complete and full performance, when due, and no matter how the same shall become due, of all obligations and undertakings of Company to Agent or such Holder under, by reason of, or pursuant to any of the Obligation Documents.

(c) If Company shall for any reason fail to pay any Obligation, as and when such Obligation shall become due and payable, whether at its stated maturity, as a result of the exercise of any power to accelerate, or otherwise, each Guarantor will, upon demand by Agent, pay such Obligation in full to Agent for the benefit of Agent or the Holder to whom such Obligation is owed. If Company shall for any reason fail to perform promptly any Obligation, each Guarantor will, upon demand by Agent, cause such Obligation to be performed or, if specified by Agent, provide sufficient funds, in such amount and manner as Agent shall in good faith determine, for the prompt, full and faithful performance of such Obligation by Agent or such other Person as Agent shall designate.

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(d) If either Company or any Guarantor fail to pay or perform any Obligation as described in the immediately preceding subsections (a), (b), or (c) each Guarantor will incur the additional obligation to pay to Agent, and each Guarantor will forthwith upon demand by Agent pay to Agent, the amount of any and all expenses, including fees and disbursements of Agent’s counsel and of any experts or agents retained by Agent, which Agent may incur as a result of such failure.

(e) As between Guarantors and Agent or Holders, this Guaranty shall be considered a primary and liquidated liability of each Guarantor.

(f) The liability of each Guarantor (other than ECO) hereunder shall be limited to the maximum amount of liability that can be incurred without rendering this Guaranty, as it relates to such Guarantor, voidable under applicable law relating to fraudulent conveyance or fraudulent transfer, and not for any greater amount.

Section 3. Unconditional Guaranty .

(a) No action which Agent or any Holder may take or omit to take in connection with any of the Obligation Documents, any of the Obligations (or any other indebtedness owing by Company to Agent or any Holder), or any Security, and no course of dealing of Agent or any Holder with any Obligor or any other Person, shall release or diminish any Guarantor’s obligations, liabilities, agreements or duties hereunder, affect this Guaranty in any way, or afford any Guarantor any recourse against Agent or any Holder, regardless of whether any such action or inaction may increase any risks to or liabilities of Agent or any Holder or any Obligor or increase any risk to or diminish any safeguard of any Security. Without limiting the foregoing, each Guarantor hereby expressly agrees that Agent and Holders may, from time to time, without notice to or the consent of any Guarantor, do any or all of the following:

(i) Amend, change or modify, in whole or in part, any one or more of the Obligation Documents and give or refuse to give any waivers or other indulgences with respect thereto.

(ii) Neglect, delay, fail, or refuse to take or prosecute any action for the collection or enforcement of any of the Obligations, to foreclose or take or prosecute any action in connection with any Security or Obligation Document, to bring suit against any Obligor or any other Person, or to take any other action concerning the Obligations or the Obligation Documents.

(iii) Accelerate, change, rearrange, extend, or renew the time, rate, terms, or manner for payment or performance of any one or more of the Obligations (whether for principal, interest, fees, expenses, indemnifications, affirmative or negative covenants, or otherwise).

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(iv) Compromise or settle any unpaid or unperformed Obligation or any other obligation or amount due or owing, or claimed to be due or owing, under any one or more of the Obligation Documents.

(v) Take, exchange, amend, eliminate, surrender, release, or subordinate any or all Security for any or all of the Obligations, accept additional or substituted Security therefor, and perfect or fail to perfect Agent’s or Holders’ rights in any or all Security.

(vi) Discharge, release, substitute or add Obligors.

(vii) Apply all monies received from Obligors or others, or from any Security for any of the Obligations, as Agent or Holders may determine to be in their best interest, without in any way being required to marshal Security or assets or to apply all or any part of such monies upon any particular Obligations.

(b) No action or inaction of any Obligor or any other Person, and no change of law or circumstances, shall release or diminish any Guarantor’s obligations, liabilities, agreements, or duties hereunder, affect this Guaranty in any way, or afford any Guarantor any recourse against Agent or any Holder. Without limiting the foregoing, the obligations, liabilities, agreements, and duties of Guarantors under this Guaranty shall not be released, diminished, impaired, reduced, or affected by the occurrence of any or all of the following from time to time, even if occurring without notice to or without the consent of any Guarantor:

(i) Any voluntary or involuntary liquidation, dissolution, sale of all or substantially all assets, marshalling of assets or liabilities, receivership, conservatorship, assignment for the benefit of creditors, insolvency, bankruptcy, reorganization, arrangement, or composition of any Obligor or any other proceedings involving any Obligor or any of the assets of any Obligor under laws for the protection of debtors, or any discharge, impairment, modification, release, or limitation of the liability of, or stay of actions or lien enforcement proceedings against, any Obligor, any properties of any Obligor, or the estate in bankruptcy of any Obligor in the course of or resulting from any such proceedings.

(ii) The failure by Agent or any Holder to file or enforce a claim in any proceeding described in the immediately preceding subsection (i) or to take any other action in any proceeding to which any Obligor is a party.

(iii) The release by operation of law of any Obligor from any of the Obligations or any other obligations to Agent or any Holder.

(iv) The invalidity, deficiency, illegality, or unenforceability of any of the Obligations or the Obligation Documents, in whole or in part, any bar by any statute of limitations or other law of recovery on any of the Obligations, or any defense or excuse for failure to perform on account of force majeure, act of God, casualty, impossibility, impracticability, or other defense or excuse whatsoever.

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(v) The failure of any Obligor or any other Person to sign any guaranty or other instrument or agreement within the contemplation of any Obligor, Agent or any Holder.

(vi) The fact that Guarantors may have incurred directly part of the Obligations or is otherwise primarily liable therefor.

(vii) Without limiting any of the foregoing, any fact or event (whether or not similar to any of the foregoing) which in the absence of this provision would or might constitute or afford a legal or equitable discharge or release of or defense to a guarantor or surety other than the actual payment and performance by Guarantors under this Guaranty.

(c) Agent and Holders may invoke the benefits of this Guaranty before pursuing any remedies against any Obligor or any other Person and before proceeding against any Security now or hereafter existing for the payment or performance of any of the Obligations. Agent and Holders may maintain an action against any Guarantor on this Guaranty without joining any other Obligor therein and without bringing a separate action against any other Obligor.

(d) If any payment to Agent or any Holder by any Obligor is held to constitute a preference or a voidable transfer under applicable state or federal laws, or if for any other reason Agent or any Holder is required to refund such payment to the payor thereof or to pay the amount thereof to any other Person, such payment to Agent or such Holder shall not constitute a release of any Guarantor from any liability hereunder, and each Guarantor agrees to pay such amount to Agent or such Holder on demand and agrees and acknowledges that this Guaranty shall continue to be effective or shall be reinstated, as the case may be, to the extent of any such payment or payments. Any transfer by subrogation which is made as contemplated in Section 6 prior to any such payment or payments shall (regardless of the terms of such transfer) be automatically voided upon the making of any such payment or payments, and all rights so transferred shall thereupon revert to and be vested in Agent and Holders.

(e) This is a continuing guaranty and shall apply to and cover all Obligations and renewals and extensions thereof and substitutions therefor from time to time.

Section 4. Waiver . Each Guarantor hereby waives, with respect to the Obligations, this Guaranty, and the other Obligation Documents:

(a) notice of the incurrence of any Obligation by Company, and notice of any kind concerning the assets, liabilities, financial condition, creditworthiness, businesses, prospects, or other affairs of Company (it being understood and agreed that: (i) e