Groundwater monitoring in the upper Queen Creek and Devils Canyon watersheds was initiated by RCM in early 2004.  The current RCM groundwater monitoring program includes 19 wells, boreholes or shafts.  Based on results of hydrogeological characterization studies conducted to date, three principal aquifers have been identified.  The purpose of the groundwater monitoring program is to provide hydrologic data for continued development and refinement of the conceptual hydrogeologic model for the ALT aquifer and adjacent aquifers in the study area that might be impacted by block-cave mining operations proposed by RCM in the Oak Flat area.