I once met two blokes who in the drought of the, cant fully remember the year, but in the early 2000's where just about every major river dried up. They heard from someone that in the Bidgee people saw bottles sticking up out of the mud!
They checked it out and saw it was true. So hired quad bikes or whatever and went there riding up and down the sides stopping every so often and collecting them and anything else of interest. They showed me rare black horse bottles, rare toothpaste ceramic (think thats what they were made of) jar type things and other amazing finds. These two guys creamed it there. How many thousands of dollars worth they found is anyones guess. But they sure did find a lot. From what they told me they never saw anyone else at the time doing it. Heard similar from guys detecting lakes or reservoirs at the time that had when been made flooded old small village/town sites finding coins, jewelry, sovs.