Four key issues remain unsettled as negotiators for a Colorado River drought-adaptation plan wrap up discussions and prepare to send a complex package of water-saving proposals to the Arizona Legislature. Farmers, developers and officials of the $4 billion Central Arizona Project said Tuesday they still aren’t satisfied with various provisions in a proposed drought contingency plan aimed at propping up imperiled Lake Mead. Because of that, negotiations over details will probably have to continue even when the Legislature starts debating the plan next week.