Exhibit 99.1

April 7, 2011

Mr. Richard Finucane

Chief Engineer

Nytis Exploration Company, LLC

2501 Broadway Street

Catlettsburg, KY 41129

Dear Mr. Finucane:

At your request, Cawley, Gillespie & Associates, Inc. have examined the estimates as of January 1, 2011 set forth in the attached table as prepared by Nytis Exploration Company, LLC with respect to the proved developed producing reserves of Interstate Natural Gas Company. Our examination included such tests and procedures as we considered necessary under the circumstances to render the opinion set forth herein. These estimates are summarized as follows:

We are independent with respect to Nytis Exploration Company, LLC and Interstate Natural Gas Company as provided in the Standards Pertaining to the Estimating and Auditing of Oil and Gas Reserve Information promulgated by the Society of Petroleum Engineers. Neither

Cawley, Gillespie & Associates, Inc. nor any of its employees has any interest in the subject properties. Neither the employment to make this study nor the compensation is contingent on the results of our work or the future production rates for the subject properties. We have not made any field examination of the subject properties.

It should be understood that our audit and the development of our reserves forecasts do not constitute a complete reserve study of the oil and gas properties of Interstate Natural Gas Company. In the conduct of our report, we have not independently verified the accuracy and completeness of information and data furnished by Nytis Exploration Company, LLC with respect to ownership interests, oil and gas production, historical costs of operation and developments, product prices, agreements relating to current and future operations and sales of production. Furthermore, if in the course of our examination something came to our attention which brought into question the validity or sufficiency of any of such information or data, we did not rely on such information or data until we had satisfactorily resolved our questions relating thereto or independently verified such information or data.

The forecasts described herein are estimates only and should not be construed as being exact quantities. They may or may not be actually recovered. Moreover, these estimates may increase or decrease as a result of future operations.

Please be advised that, based upon the foregoing, in our opinion the above-described estimates of Interstate Natural Gas Company’s proved developed producing reserves are, in the aggregate, reasonable within the established audit tolerance guidelines of (+ or -) 10% and have been prepared in accordance with generally accepted petroleum engineering and evaluation principles as set forth in the Standards Pertaining to the Estimating and Auditing of Oil and Gas Reserve Information promulgated by the Society of Petroleum Engineers.

This letter is solely for the information of Nytis Exploration Company, LLC. This letter should not be used, circulated or quoted for any other purpose without the express written consent of Cawley, Gillespie & Associates, Inc. or except as required by law.

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RESERVES AND ECONOMICS

AS OF DATE: 01/2011