Augusta Resource Announces Publication of Rosemont Draft ROD Approving Preferred Alternative

Toronto, Ontario, December 12, 2013 – Augusta Resource Corporation (TSX/NYSE MKT: AZC) (“Augusta” or “the Company”) is pleased to announce that Rosemont Copper’s draft Record of Decision (“ROD”) and final Environmental Impact Statement (“EIS”) has been printed and published by the U.S. Forest Service (“USFS”). The Notice of Availability for the final EIS is expected to be published in the Federal Register on December 13, 2013, and the draft ROD to be available on December 16, 2013.

The draft ROD selects Alternative 4, the Barrel Alternative, which was identified as the USFS preferred alternative in the final EIS. This alternative complies with applicable Federal and State laws and regulations and is considered to be the environmentally preferable alternative as it, where feasible, minimizes adverse environmental and social impacts. The draft ROD also includes mitigation measures that have been developed to avoid, minimize, rectify, reduce, eliminate or compensate for the impacts that the action alternative would have on the environment.

As stated in the Draft ROD by Jim Upchurch, Forest Supervisor, Coronado National Forest:

“With these factors in mind, I did not take this decision lightly...My decision to approve the proposal is guided by Federal law...My decision allows Rosemont Copper to develop its mineral resource while requiring a wide array of mitigation and monitoring steps that will minimize or avoid impacts on NFS lands to the extent practicable...Importantly, my decision implements an alternative that will allow Rosemont Copper to comply with applicable Federal laws and regulations.”

The legal notice for the draft ROD is planned to be published on December 31, 2013, with the comment period, which is statutorily limited to 45 days, to commence on January 1, 2014.

“The issuance of the draft ROD, which includes the approval of the preferred Barrel alternative, provides the roadmap for the operation of the Rosemont Copper Project,” commented Gil Clausen, Augusta’s President and Chief Executive Officer. “This decision is the conclusion of six years of analysis conducted by the USFS and the cooperating agencies. This input allowed the USFS to develop a sound alternative that will meet all of the required regulations while addressing public concerns and issues. Rosemont is very pleased with this decision and commends the USFS for their significant efforts.”