The Army Corps of Engineers website provides access to different river basins managed by them. For example, the Alabama-Coosa-Tallapoosa River Basin water management page includes links to the latest water levels and discharge information about reservoirs within the basin.
ACT Basin Water Management Areas of Responsibility
Another example is a U.S Army Corps of Engineers southeast regional drought information site sponsored by the Corps' South Atlantic Division in Atlanta. The site contains basic information about drought impacts in the southeast and real time information on the status of rivers and federal reservoirs in the region.