It's no different then a beach, during times of high water that sand gets reshaped, items get pushed and shoved around and redistributed. If that place has history then there's old items in there somewhere. If there's any type of a dam then I'd start around the edges of the water just below that dam. The stronger volume of water coming over the dam during periods of high water will often scatter items like old coins out of the channel and towards the shoreline, so this is a really good place to start looking for those older period connections. If you start hitting some old coins, which I can't image that you won't, then I'd really research the heck out of the place in search of those older swimming areas that may have existed back in the day. Take the time research how gold travels and is eventually deposited in gold bearing streams, items such as silver coins and heavier pieces of jewelry, like gold rings, are pretty much distributed in the same way. Also look for any feature that can act as a trap, such as rocks, rocky outcroppings, crevices, etc. Also, check the depth of that sand as you snoop around, more then likely there are places with much firmer bottoms under that sand.