In 1998, the United Stated Environmental Protection Agency (EPA) released the Interim Record of Decision for the Puente Valley Operable Unit (PVOU) that described, in part, EPA’s selected remedy for both shallow and intermediate zone contamination. It stated that the remedial action for the shallow zone shall prevent contaminated groundwater from migrating beyond its current lateral and vertical extent as described in the Remedial Investigation/Feasibility Study (RI/FS). The remedial action selected by EPA for the intermediate zone shall prevent contaminated groundwater from migrating beyond the San Gabriel Valley Water Company (SGVWC) B7 Well Field Area (an area defined by 14 wells in the immediate area of SGVWC’s B7 Well Field). Furthermore, perchlorate was recently discovered in the B7 Well Field Area causing EPA to further evaluate remedy options. In 2005 EPA issued an Explanation of Significant Differences for the PVOU mandating treatment for all emergent chemicals in both the shallow and intermediate zones.
The San Gabriel Basin Water Quality Authority has helped to fund the SGVWC treatment facilities.