Okay, I will admit that smarter people than me have been thinking about this issue for a long time.

Having said that.......

If MMD is empty almost all the time, and Buckley is only used as a trapping facility, the solution seems obvious. Take out Buckley, open the gates on MMD to let the fish pass unobstructed. If high water presents a flood control issue, lower the gates at MMD to protect downstream areas.

Presto! No need to trap/haul fish. No need for Buckley. You maintained existing levels of flood control (@MMD). And you just saved a few millon dollars.