Two species of fish are immediate beneficiaries: the federally threatened leopard darter and the Ouachita-strain smallmouth bass.

CNN: Migrating fish get help in uphill battle

The red-veined darter is a rare visitor from southern Europe and was spotted at Brecknock Wildlife Trust's Brechfa Pool nature reserve above Llyswen.

BBC: Rare dragonfly visitor at reserve

The infamous snail-darter, a three-inch fish that held up for years the construction of a federal dam in Tennessee, has happily survived the dam's arrival.

ECONOMIST: Wild-life conservation: Landscape or animals first? | The