The Hanford Site Groundwater Protection Management Program recognized the need to integrate monitoring well activities in a centralized manner. A key factor to Hanford Site well integration was the need to clearly identify a responsible party for each of the wells. WHC was asked to identify all wells on site, the program(s) using each well, and the program ultimately responsible for the well. This report lists the custodian and user(s) for each Hanford well and supplies a comprehensive list of all decommissioned and orphaned wells on the Hanford Site. This is the first update to the original report released in December 1993.