This is very general. An overview for your planning.
Not carved in stone.
United States Drought Monitor > Home
To be more precise do some research on this board.
River by suggested River.
Some rivers will be OK to run even in droughtish areas.
Many will have stretches that are going to be doable but not the full meal deal in August.
Others are subject to permit and getting on a river may be pretty hard.
As pointed out. August can be dry and much lower cfs.
Think hat and sunscreen.
I know aircraft luggage fees are dear but could you bring some water with you?