On a cost benefit analysis where is the benefit of spending 10 million dollars of taxpayer money?

It is of no benefit to the yacht club which is well protected and has floating docks. Likewise for the Pines Point Marina that in any case is private and that community is well protected with rip wrap.

By the way, to put this 10 million of rocks and dirt  in perspective, OP spent 4.7 million 10 years ago for the new Yacht Club. Proudly we have something to show for it.

Take a good look at the map above or catch the layout from the 90 bridge. The project wraps in a U shape along the Osprey Point's Association's property The only beneficiary of this project is the privately gated Osprey Point Condo Association. Who owns the islands that the project also seeks to envelop is questionable.

if nature takes it course and the islands do end up under water it is not a big deal. If Osprey Point has to spend some money to fortify their shore line in an environmentally friendly way they are no different from other waterfront property owners that pay to take care of their property in a like manner.

Our hopeless Congress keeps threating to shut down the government because of the rising debt ceiling. Instead of going after social security and health benefits maybe they should stop pissing our tax dollars into the river at our bequest