The California Department of Corrections and Rehabilitation (CDCR) proposes to reactivate a potable water well at the California Institution For Men (CIM) in order to meet ongoing water supply needs, including source reliability and redundancy. The facility has an existing permit to operate a Domestic Water Supply System (permit #: 04-91-10). The permit was amended in January 2019 in order to install and operate a poly-orthophosphate injection system for corrosion control and added Granular Activated Carbon (GAC) as an approved treatment for removal of 1,2,3-trichloropropane (1,2,3-TCP) (Permit Amendment No. 05-13-19PA-001). CDCR has now begun planning the reactivation of Well 01 which was deactivated sometime after 2018 after samples contained detected concentrations of 1, 2, 3-TCP, a constituent with a primary drinking water maximum contaminant level (MCL) of 0.005 micrograms per liter (ug/L). CDCR has successfully negotiated a process with the State Water Resources Control Board Division of Drinking Water of the (DDW) for reactivation of Well 01 following removal of the well as a source to the CIM water system, pending a review of the potential effect of using Well 01 on the treatment system for reported 1, 2, 3-TCP concentrations. As as stated above, the existing water treatment process uses GAC to remove nitrate, tetrachloroethylene, constituents that cause bad taste and odor and can also remove 1, 2, 3-TCP. Based on initial discussions with DDW a concern was expressed that reactivation of Well 01 would introduce 1, 2, 3-TCP at higher concentrations than the other wells. Prior to activation of Well 01, DDW requested an engineering review of the existing treatment process for its suitability to remove 1, 2, 3-TCP. The engineering review was prepared on February 3, 2022 and subsequently submitted to DDW demonstrating the treatment system’s ability to treat water from Well 01.