WHITESBURG — State environmental officials will vote Wednesday to allow less Chattahoochee River water, at times, to flow below Atlanta, a proposal that angers downstream communities that fear a return to the 1990s when the big city’s sewage discharges polluted their lives. Locals, long suspicious of the motives of Atlanta’s water czars, see the lower-flow plan as a way to keep more water in Lake Lanier to slake what they view as the metro region’s insatiable growth. Hoarding water upstream, particularly during times of drought, could also keep the ever-precious resource from Alabama and Florida, downstream users of the Chattahoochee who’ve sued Georgia over the “equitable apportionment” of the river.