U.S. Geothermal Inc. Updates Drilling at El Ceibil

BOISE, IDAHO--(Marketwired - June 25, 2013) - U.S. Geothermal Inc. (NYSE MKT: HTM )(TSX: GTH ), a leading renewable energy company focused on the development, production, and sale of electricity from geothermal energy, announced today that its wholly owned subsidiary, U.S. Geothermal Guatemala, S.A., completed drilling well EC-1 at the El Ceibillo Project.

Well EC-1 was drilled to a total depth of 4,829 feet (1,472 meters) and encountered a bottom-hole temperature of 491°F (255°C), with the temperature gradient at the bottom of the hole rising at a rate of 7.1°F/100 feet (129.1°C/km). High temperatures in excess of 392°F (> 200°C) were encountered in the well beginning at a depth of 2,625 feet (800 meters), which represents a potential high temperature reservoir interval in excess of 2,204 feet (672 meters). Permeability was encountered and a slotted liner capable of supporting production was placed in the well. A preliminary cleanout flow from the well looked favorable and warrants formal testing. Flow test equipment is currently being fabricated for a planned test, which is expected to be performed within the next 4 to 6 weeks.

Well EC-1 was originally planned for a depth of 3,280 feet (1,000 meters), however due to favorable drilling conditions, geology, and increasing temperature; the well depth was extended and was completed within the original budget.

"We are very excited about the preliminary results seen from our first production depth well at our El Ceibillo project in Guatemala," said Doug Glaspey, President and COO of US Geothermal. "Reservoir temperatures within the El Ceibillo area of our concession are significantly higher than we anticipated, and as a result of favorable drilling conditions, our projected drilling costs for production size wells appear to be at or lower than we have planned."

Please visit our website at: www.usgeothermal.com .

About U.S. Geothermal Inc.:

U.S. Geothermal Inc. is a leading renewable energy development company that is operating geothermal power projects at Raft River, Idaho, San Emidio, Nevada, and Neal Hot Springs, Oregon. El Ceibillo is an advanced stage, high temperature development project located in Guatemala. The company holds geothermal energy rights to 69,500 acres comprising six advanced stage geothermal development projects.

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. These statements are based on U.S. Geothermal Inc.'s current expectations and beliefs and are subject to a number of risks and uncertainties that can cause actual results to differ materially from those described, including but not limited to, the results from the exploration, production and injection well drilling at El Ceibillo. Readers are cautioned to review the risk factors identified by the company in its filings with Canadian and US securities agencies. 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.

The NYSE MKT and the TSX do not accept responsibility for the adequacy of this release.