The first three phases of Nye County, Nevada’s Early Warning Drilling Program (EWDP) were conducted from January, 1999, through March, 2002, under a co-operative science grant from the Department of Energy’s (DOE’s) Yucca Mountain Project. The purpose of the EWDP is to establish a groundwater monitoring system to protect present and future residents of Nye County against potential groundwater radionuclide contamination originating from the proposed Yucca Mountain high-level nuclear waste repository. The program is also intended to provide geologic and hydrologic data needed to understand the hydrogeologic system downgradient of Yucca Mountain. This information has been absent from DOE’s Yucca Mountain site characterization program and has resulted in significant uncertainty in DOE's performance assessment models. The previously uncharacterized targeted area is located in a complex hydrogeologic setting between Yucca Mountain and the Nye County community of Amargosa Valley located approximately 20 miles to the south. The questions to be investigated are: 1) the lithologic and hydraulic properties of the valley-fill sediments; 2) regional groundwater flow patterns; 3) regional recharge in the system; and 4) origin of the spring deposits. By understanding this critical hydrogeologic information, the monitoring system can be better designed to protect the water resources of Nye County. During the first three phases of the EWDP, approximately 23,225 feet were drilled, sampled, and logged; and a total of 26 wells were completed to depths ranging from 50 to 3075 feet. Well completion diagrams, geologic logs, geophysical logs, laboratory hydrologic property test data, piezometric surface data, water quality data, and aquifer test data have been produced by Nye County to address data gaps. Representative data will be summarized and plans for future EWDP activities will be described.