U.S. Geothermal Inc. Advances Two Significant Development Projects

BOISE, IDAHO--(Marketwired - Aug. 6, 2015) - U.S. Geothermal Inc. (TSX:GTH)(NYSE MKT:HTM), a leading renewable energy company focused on the development, production, and sale of electricity from geothermal energy, is pleased to announce it is advancing two significant development projects. The Company's wholly owned subsidiary, U.S. Geothermal Guatemala, S.A., started drilling well EC-2 at the El Ceibillo Project today. Additionally, the Company has successfully completed a flow test program on the three largest production wells at the WGP Geysers project in northern California confirming the existence of approximately 30 MW of steam. Together, both projects have the capability of adding some 80 megawatts of electricity to the company's annual capacity

At the El Ceibillo project in Guatemala, drilling started on Well EC-2 which has a planned depth of 1,968 feet (600 meters). EC-2 will test a high temperature anomaly identified by a 2014 temperature gradient drilling program. Drilling was suspended after well EC-1 was drilled in June of 2013 until the project schedule for the concession could be modified. The Ministry of Energy and Mines approved the modified project schedule on July 21, 2015. The 8 day public comment period, which followed that approval, concluded without receiving any comments. We expect to receive the amended concession contract before the end of August.

At the WGP Geysers project, located about 1 1/2 hours north of San Francisco, in Sonoma County, the three production wells with the highest flow rates were tested. All three wells produced superheated steam with estimated flow rates at or above the rates measured when the wells were first drilled during 2008 and 2009, confirming that the wells are open and available for production. An independent, world recognized geothermal consulting firm, GeothermEx Inc., designed and monitored the flow tests, and collected test data for their analysis. The reservoir report is expected by the end of August, and will be used to guide final development of the project.

"With approximately 30 megawatts of steam drilled, tested and ready for production at Geysers, we are actively pursuing discussions in support of a power purchase agreement for this, our most advanced stage development project" said Dennis Gilles, CEO of US Geothermal. "Additionally, our geothermal concession in Guatemala holds great promise and we anticipate that the drilling results from our next few wells will allow us to confirm the geothermal resource. We expect to be able to produce from 25 to 50 megawatts of electricity when the project is completed. The government of Guatemala strongly supports renewable energy, and we look forward to continuing to work with them to make the development of this first, 100% private geothermal concession a big success."

About U.S. Geothermal Inc.:

U.S. Geothermal Inc. is a leading and profitable renewable energy company focused on the development, production and sale of electricity from geothermal energy. The company is currently operating geothermal power projects at: Neal Hot Springs, Oregon, San Emidio, Nevada and Raft River, Idaho for a total power generation of approximately 45 MWs. The company is also developing projects at: the Geysers, California; a second phase project at San Emidio, Nevada; the El Ceibillo project located near Guatemala City, Guatemala; and at Crescent Valley, Nevada. U.S. Geothermal's growth strategy is to reach 200 MWs of generation by 2020 through a combination of internal development and strategic acquisitions.

The information provided in this news release may contain forward-looking statements within the definition of the Safe Harbor provisions of the US Private Securities Litigation Reform Act of 1995. Readers are cautioned to review the risk factors identified by the company in its filings with US and Canadian securities agencies. All statements, other than statements of historical fact, included herein, without limitation, statements relating to the future operating or financial performance of U.S. Geothermal, are forward-looking statements. Forward-looking statements are frequently, but not always, identified by words such as "expects", "anticipates", "believes", "intends", "estimates", "potential", "possible", and similar expressions, or statements that events, conditions, or results "will", "may", "could", or "should" occur or be achieved. These forward-looking statements may include statements regarding perceived merit of properties; interpretation of the results of well tests; project development; resource megawatt capacity; capital expenditures; timelines; strategic plans; or other statements that are not statements of fact. Forward-looking statements involve various risks and uncertainties. There can be no assurance that such statements will prove to be accurate, and actual results and future events could differ materially from those anticipated in such statements. Important factors that could cause actual results to differ materially from U.S. Geothermal's expectations include the uncertainties involving the availability of financing in the debt and capital markets; uncertainties involved in the interpretation of results of well tests; the need for cooperation of government agencies in the development and operation of properties; the need to obtain permits and governmental approvals; risks of construction; unexpected cost increases, which could include significant increases in estimated capital and operating costs; and other risks and uncertainties disclosed in U.S. Geothermal's Annual Report on Form 10-K for the year ended December 31, 2014 filed with the United States Securities and Exchange Commission and Canadian securities regulatory authorities and in other U.S. Geothermal reports and documents filed with applicable securities regulatory authorities from time to time. Forward-looking statements are based on management's expectations, beliefs and opinions on the date the statements are made. U.S. Geothermal Inc. assumes no obligation to update forward-looking statements if management's expectations, beliefs, or opinions, or other factors, should change.

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