U.S. GEOTHERMAL INC.
U.S. Geothermal Announces Substantial Increase in the San Emidio II Reservoir Capacity

U.S. Geothermal Inc. (the "Company") (NYSE MKT:HTM), a leading and profitable renewable energy company focused on the development, production, and sale of electricity from geothermal energy, announced that the estimate of the geothermal reservoir capacity associated with its San Emidio II project has increased from the earlier estimate of 10 net megawatts, to an estimated generation capacity of up to 47 net megawatts. This increased capacity is in addition to the current 10 megawatts being produced by the existing San Emidio I plant.

In early 2016, five 1,000 foot temperature gradient wells were drilled in the Southwest Zone and later in the year, two of those wells were deepened. Both wells intersected a high permeability, high temperature geothermal reservoir. Data from flow tests that took place in late 2016 on the two deepened wells were incorporated into a Probabilistic Power Density model developed by Geothermal Science Inc., an independent geothermal reservoir engineering company. Based on the flow rate and temperature produced by the two wells, and by measurement of pressure response across the wellfield, the model estimates that the area encompassed by the five wells drilled in 2016 (.18 square miles) has a 90% probability of 18.8 net megawatts of generation capacity as the Minimum. A larger area (1.4 square miles), defined by additional temperature gradient wells and geophysics, has a 50% probability of 47 net megawatts of generation capacity and was rated as the Most Likely outcome.

"This large increase in the size of the San Emidio II reservoir is an exceptional result from our development program," said Dennis Gilles, Chief Executive Officer. "Having the ability to add a larger power plant to our San Emidio complex will help reduce capital and operating costs, and give us a very cost competitive project. Additionally, it will allow us to deploy two, or possibly three, of the previously acquired power plants whose acquisition we had announced in early 2016."

The three remaining 1,000-foot-deep temperature gradient wells all have high temperature gradients and bottomhole temperatures indicating that an active geothermal resource exists below them. Permits to deepen these three remaining wells down into the production reservoir were received from the Bureau of Land Management and State of Nevada in late December. Subject to weather conditions, drilling to deepen those wells is planned for the first quarter of 2017. If the three wells intersect geothermal resource with similar permeability and temperature, the extent of the resource may be expanded and its power generation estimate increased. Additional permitting that will allow for more drilling to further expand the resource and to prepare for site development and construction activities is also underway.

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 an additional 90 MWs of projects at: the Geysers, California; a second phase project at San Emidio, Nevada; at Crescent Valley, Nevada; and the El Ceibillo project located near Guatemala City, Guatemala. U.S. Geothermal's growth strategy is to reach 200 MWs of generation by 2021 through a combination of internal development and strategic acquisitions.

For more information, please visit our website at: http://www.usgeothermal.com

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, development schedules or estimated resources 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, 2015 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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