I've been on Enid and watched as they dredged a ramp. Scoop the mud up and throw it to the side. When the lake refills the mud washes back in. There are plenty of hollows in the woods that could have a weir built and the mud pumped into them and out of the ramp area. That's how they extended the river front park at Memphis along Riverside drive. I know that some will say you can't do that because you'll expose chemicals like DDT. What are they doing now?
I looked at google earth and the ramp at Cossar is closed. I know that's state. So I guess it would be best to contact them.