Environmentalists want Sen. John McCain to spend some of his political capital and stop legislation that limits Fort Huachuca's responsibility for water use surrounding the installation. Critics of the proposal say it will kill the San Pedro - Arizona's last undammed, free-flowing river. They say the fort's expansion and accompanying growth around Sierra Vista will deplete the groundwater that keeps the river running. But the measure's sponsor, Rep. Rick Renzi, R-Ariz., says it's unfair to hold the Army liable for water use beyond its direct control. He argues environmental regulations are threatening the fort's future. Activists have been targeting McCain...