I'm not convinced that larger lakes are either more important to the environment or more costly to maintain. On an individual basis yes, but I'd make the assumption that it would cost more to manage mussel infestations on 10 lakes less than 10,000 acres than one Don Pedro. So I don't think your plan is particularly cost-effective.

It'd be interesting if someone had the actual average costs for managing mussels on a lake of X size with Y type dam.

All the environmental stuff? Pfff....