The city was/is using up a very significant portion of the Chattahoochee and its reserves and tributaries, causing severe issues downstream for Florida, Georgia and Alabama communities. They also injected sewage into the water, causing silting issues. Additionally, faced with shortages, the GA state legislature proposed to run a water pipeline from the other side of the state, essentially stealing more water from other GA sources further east (Savannah area, iirc).
Last I was paying attention, GA state legislature had filed a request to take more water out of the Chattahoochee, over objections from Alabama. Went to a Federal judge, who pointed out that Atlanta's use of water from Lake Lenier was actually illegal, in excess of the original authorizations put in place when it was constructed by the Army Corps of Engineers. Oops.
https://en.m.wikipedia.org/wiki/Lake_Lanier
Go look up the "Tri-state water wars", pretty crazy stuff.
I'm not sure the distinction is all that meaningful.