| 1.   | Recitals. The      above recitals are incorporated herein and made a part    hereof. |
|----------------|--------------------------------------------------------------------------------------|

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| 2.        | Loan Statement.      Borrower and Lender hereby confirm that as of the date hereof, (i)      there is no accrued and unpaid interest under the Loan, and (ii) there is      no outstanding principal balance under the Loan. The maximum principle      amount of the note is$3,000,000.00 |
|----------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

| 3.   | Interest Rate.      Interest shall continue to accrue under the Note on the outstanding      balance at a floating rate equal to Lender’s Prime Rate (as defined in the      Note), as in effect from time to time; provided, however, that      such interest rate will not decrease below fixed minimum rate of      3.50%. |
|----------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

| 4.   | Note Payments/Maturity      Date. Commencing September 5, 2009 and continuing on the fifth      (5th)      day of each and every calendar month during the term of the Loan, payments      of interest only shall continue to be due and payable. The Loan maturity      date is hereby extended to August 5,2010. |
|----------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

| 5.   | Schedule GC to Loan      Agreement. Schedule DD to the Loan Agreement is hereby deleted in      it’s entirety and replaced with that certain Amended and Restated Schedule      “GC” to BB&T Loan Agreement dated of even date herewith and attached      hereto as Exhibit      A. |
|----------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

| 6.   | Modification of Loan      Documents. |
|----------------|--------------------------------------|

| A.   | The      Note, Security Agreement, Loan Agreement and remaining Loan Documents are      hereby modified to reflect and incorporate the terms and provisions of the      Loan modifications as described in paragraphs 3 thorough 5      above. |
|----------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

| B.   | The      terms “Note”, “Security Agreement”, “Loan Agreement”, and all other      defined documents as referenced in the Loan Documents, shall be deemed to      mean such documents, as modified by this Agreement. In addition, this      Agreement shall be deemed to be a LoanDocument. |
|----------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

| 7.   | Modification      Costs. Borrower further agrees to pay the Lender at the time of the      execution of this Agreement, a Loan extension fee in the amount of      $1,500.000. |
|----------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

| 8.   | Ratification and      Renewal. The Borrower hereby ratifies and renews it’s covenants and      agreements to pay the Loan in accordance with the terms and provisions of      the Note, as modified by this Agreement; and the Borrower otherwise hereby      ratifies and renews its covenants and agreements to perform, comply with      and be bound by all other terms and provisions of the Note and the Loan      Documents, all as modified by this Agreement. The Borrower also hereby      confirms that the Security Agreement continues to secure repayment of the      Note, as modified by this Agreement. Further, the Borrower covenants and      warrants that each and every provision of the Note and Loan Documents, as      modified by this Agreement, are in full force and effect and are the      lawful and binding obligations of Borrower, enforceable in accordance with      their respective terms. |
|----------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

| 9.   | Waiver.  The      Borrower acknowledges Lender as the owner and holder of the Note, and the      secured party under Security Agreement, and covenants and agrees that      there are no defenses, set-offs, or counter-claims against Lender, with      respect to the Note and the Loan Documents, as modified by the terms of      this Agreement, or otherwise, or with respect to the Loan or with respect      to the collection or enforcement of any of the same. The parties to this      Agreement do not intend this Agreement to be construed as a novation of      the Note. |
|----------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

| 10.   | Further      Assurances. The parties agree to execute and deliver any and all      instruments and documents reasonably necessary or required from time to      time to effect the terms and intent of this  Agreement. |
|-----------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

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| 11.   | Entire      Agreement. This Agreement contains the entire agreement of the      parties hereto with respect to the modification of the Loan, and no other      agreement, statement or promise made by any party hereto, or any employee,      officer, agent, or attorney of any party hereto, shall be valid or      binding. |
|-----------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

| 12.   | Binding Effect.      Each and every of the terms and provisions of this Agreement shall be      binding upon and shall inure to the benefit of the parties hereto and      their respective heirs, successors, personal representatives and      assigns. |
|-----------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

| 13.   | Governing Law.      This Agreement shall be governed by, construed under, and interpreted and      enforced in accordance with the laws of the Commonwealth of Virginia, but      without regard for Virginia’s laws or rules regarding conflict or choice      of laws. |
|-----------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

| 14.   | Severability.      If any term, covenant, or condition of this Agreement, or the application      thereof  to any person or circumstance, shall to any extent be      invalid or unenforceable, the remainder of this Agreement, or the      application of such term, covenant or condition to other persons or      circumstances, shall not be affected hereby, and each term, covenant or      condition of this Agreement shall be valid and enforceable to the fullest      extent permitted by law. |
|-----------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

| 15.   | Headings. The      captions and headings herein are for convenience of reference only and in      no way define or limit the scope or content of this Agreement or in any      way affect its provisions. |
|-----------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

| 16.   | Modification.      The terms of this Agreement may not be changed, waived, discharged or      terminated orally, but only by an instrument in writing, signed by the      party against which enforcement of the change, waiver, discharge or      termination is asserted. |
|-----------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

| 17.   | Counterparts.      This Agreement may be executed in any number of counterparts, each of      which shall be an original but all of which together will constitute one      instrument. |
|-----------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

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|   | BORROWER:                                             |                           |
|--------|-------------------------------------------------------|--------------------------------|
|   |                                                  |                           |
|   | SUTRON      CORPORATION, a Virginia corporation  |                           |
|   |                                                  |                           |
|   |                                                  |                           |   |
|   | By:                                                   | /s/ Sidney      C. Hooper |   |
|   |                                                  | Sidney      C. Hooper     |   |
|   |                                                  | Treasurer                 |   |
|   |                                                  |                           |   |

| COMMONWEALTH OF      VIRGINIA  | )    |   |   |   |
|-------------------------------------|-----------|--------|--------|--------|
|                                | ) to-wit: |   |   |   |
| COUNTY OF      LOUDON          | )    |   |   |   |

|   | LENDER:                                        |                           |
|--------|------------------------------------------------|--------------------------------|
|   |                                           |                           |
|   | BRANCH      BANKING AND TRUST COMPANY, a  |                           |
|   | North      Carolina banking corporation   |                           |
|   |                                           |                           |   |
|   | By:                                            | /s/ Leonard      C. Lewan |   |
|   |                                           | Leonard      C. Lewan     |   |
|   |                                           | Senior      Vice President     |   |
|   |                                           |                           |   |

| COMMONWEALTH OF      VIRGINIA  | )    |   |   |   |
|-------------------------------------|-----------|--------|--------|--------|
|                                | ) to-wit: |   |   |   |
| COUNTY OF      FAIRFAX         | )    |   |   |   |

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