As requested, our hydrologists Stan Leake, Jesse Dickinson, Don Pool have conducted a technical review of Hydro-Logic Technical Memorandum "Simulated Empire Gulch Spring Discharge and Stream Flows based on the Tetra Tech (2010) Groundwater Flow Model." The Memorandum documents a modification of the Tetra Tech (2010) groundwater flow model (the original model) the simulate the Upper Empire Gulch Spring discharge and Empire Gulch streamflows. These features were not explicitly simulated in the original model. The Memorandum also describes model predictions of streamflow changes over time. Our comments, listed below, are limited to the modification to include the spring and streamflow at Empire Gulch, as specified in the Scope of Work for USGS Technical Support to Rosemont Copper Project Hydrology Working Group - Federal Agency Subgroup.
U.S. Geological Survey. 2014c. Technical Review of Hydro-Logic Technical Memorandum "Simulated Empire Gulch Spring Discharge and Stream Flows based on the Tetra Tech (2010) Groundwater Flow Model". In Letter from James Leenhouts, Director, USGS Arizona Water Science Center, to Jim Upchurch, Forest Supervisor, Coronado National Forest. Tucson, Arizona: U.S. Geological Survey. September 30.