Community leaders along the Mississippi River worried that dry southwestern states will someday try to take the river’s water may soon take their first step toward blocking such a diversion. Mayors from cities along the river are expected to vote on whether to support a new compact among the river’s 10 states at this week’s annual meeting of the Mississippi River Cities and Towns Initiative, according to its executive director Colin Wellenkamp. Supporters of a compact hope it will strengthen the region’s collective power around shared goals like stopping water from leaving the corridor.