Augusta Provides Rosemont Copper Project DEIS Update 

VANCOUVER, BC - Augusta Resource Corporation reported that in a statement dated April 30, 2010, the Coronado National Forest has delayed the release of the Draft Environmental Impact Statement (DEIS) for the Rosemont Copper project in Arizona in order to complete an additional plant study and additional groundwater modeling of development plan alternatives.

The Coronado National Forest must complete field surveys for a native plant (Hexalectris revoluta) thought to be partially coincident with one or two of the several alternative proposals for the dry stack tailings area siting on USFS land. The plant has an April-June emergent season, and survey teams are in the field to collect data throughout the season. The Company believes that avoidance of the known plant location is possible with minimal changes to project siting for the one or two potentially affected alternatives. In addition, DEIS project teams conducting detailed groundwater hydrology studies will complete further calculations on potential impacts and mitigation measures for the alternative facility sites under evaluation in the DEIS. Hydrology experts have undertaken a comprehensive calibration and sensitivity analysis of the complex predictive groundwater models. The groundwater models evaluate potential for impacts of the various alternatives for the Rosemont Copper project. Completion of these studies will allow better comparisons between the alternative siting proposals. Both studies are expected to be completed this July; a revised DEIS schedule will be available within the next two months. All other work on completing and reviewing the document for publication continues unabated. Augusta VP Sustainable Development Jamie Sturgess said: "All pertinent issues need to be addressed, and experts are completing these last two studies after delivering almost 100 technical reports over the last three years. As Rosemont nears completion of this EIS process, we are pleased to see ever-growing support from the public and elected officials." Company officials agree that this modest delay to the DEIS schedule is necessary to allow the Forest Interdisciplinary Team and its third party contractors to produce a complete and comprehensive evaluation. Scheduling for final public hearings and comment period will be released with the Notice of Availability of the DEIS. The company's address is #400 - 837 West Hastings Street, Vancouver, BC, V6C 3N6, 604.687.1717, fax: 604.687.1715, email: [email protected].