So you turned the vehicle around in the picnic shelter entrance & backed the trailer down until the boat floated ??
Seriously though ... with the lake level staying at around 703 for the last 10days, it wouldn't surprise me if the fish are bedding back in the trees.
On an even less serious note : how do you pay to launch ??

I mean, the launch fee machine is a good 15-20 feet under water ... IF it's still there & wasn't taken out before the water got to it.
No conspiracy theorist here, but it does seem to be a bit on the coincidence side that the COE gave Holmes Bend Marina the control duty of the parking lot & launch ramp just before the flooding. SO, now they'll have to clean the parking lots of all the silt/mud & debris as the lake level drops below each lot level in the coming days & weeks of the drawdown. I do hope they will be compensated for that work.