The US EPA is seeking assistance from the US DOJ in connection with a potential enforcement matter concerning the Mt. Diablo Mercury Mine, Contra Costa County, California. The site is not currently on the NPL but may be considered for listing in the future. EPA is requesting DOJ assistance in negotiating with recently identified potentially responsible parties (PRPs), and in the event negotiations are unsuccessful, for possible enforcement of a Unilateral Administrative Order under CERCLA Section 106(b), 42 U.S.C. 9606(b), and recovery of response costs pursuant to CERCLA Section 107(a), 42 U.S.C. 9607(a).