Since this is a pearl forum, I'm thinking we should probably get back to concentrating on what kind of pearls the OP found, rather than how they came to be where found. Still, it might allay some concerns to know that
Wikipedia says of Sacandaga Reservoir: Today, the local businesses benefit not only from the flood protection provided by the lake, but also from the tourist attraction and its economy that the lake has created in the area. People come from many local cities and towns to visit the lake for recreation, or to stay in their summer camps on the lake. Public access to the lake is via the many public boat launches, and public beaches; plus the campgrounds that are located on the shores of the lake.