Groundwater is monitored in hundreds of wells at the Hanford Site to fulfill a variety of requirements. Separate monitoring plans are prepared for various purposes, but sampling is coordinated and data are shared among users. DOE manages these activities through the Hanford Groundwater Performance Assessment Project, which is the responsibility of Pacific Northwest National Laboratory. The groundwater project integrates monitoring for various objectives into a single sampling schedule to avoid redundancy of effort and to improve efficiency of sample collection.This report documents the purposes and objectives of groundwater monitoring at the DOE Hanford Site in southeastern Washington State.