The state of Montana has reached an agreement with the Atlantic Richfield Co. To settle a 25-year lawsuit over environmental damage caused by mining and smelting in Butte and Anaconda, documents filed in federal court show. The documents indicate the state Department of Justice and Arco have settled on the final three outstanding natural- resource damage claims. Those remaining claims involve damage along the Clark Fork River from the Warm Springs ponds to Milltown; in the Anaconda Uplands area; and contamination of a groundwater aquifer in Butte. Details of the settlement remain confidential for now. Before it becomes final and public, the state, the company and the Environmental Protection Agency must also reach agreement on the Superfund cleanup plan for the Clark Fork River site. It’s expected the settlement will include money for Superfund remediation along the Clark Fork River, just as the 1998 settlement earmarked money for Superfund cleanup work on Silver Bow Creek. John Wardell, director of EPA’s Montana office, said the agency is asking the state to take the lead role in implementing the Superfund remedy and handling restoration work along the Clark Fork. “It makes no sense to have two government agencies trying to coordinate the activity,” he said. State Attorney General Mike McGrath has asked U.S. District Judge Sam Haddon to extend the deadline for negotiations until June 30, as talks continue. “I’m frustrated we have not reached a resolution with the EPA,” McGrath said. In December 1983 the state sued Atlantic Richfield for environmental damage along the Upper Clark Fork River Basin, damage largely assumed by Atlantic Richfield and when it acquired the assets and liabilities of previous mine operators. The state sought $765 million for damages caused and for restoration work. In 1998, the parties reached a settlement totaling roughly $215 million for all but these three remaining restoration damage claims.