Yes, this could be a real treasure and may be worth several people partnering and even worth the storing on borrowed or rented land.
The logs will have to be processed quickly or they will deteriorate, especially if they have been submerged for a long period of time. Having a small, portable mill may be an advantage. You can spend more time getting the "goody" from the logs than a big production mill.
It would be advantageous to have another pond in which the logs could be stored or the ability to sprinkle the logs heavily.
It sounds like a project that the city should partner with small business. If they could pull out the logs and have the equipment to move them, small business sawmills could produce lumber for themselves and the city.