The canal bed, now just damp and puddle-filled, is a favorite breeding ground for American toads. It's a fairly short walk to old Riley's Lock, located at the mouth of Seneca Creek. Everybody I know just calls the entire area Seneca. At one time, an old stone aqueduct carried the canal across Seneca Creek just before the creek enters the Potomac. Part of the structure washed away in the floods of 1972, but the aqueduct still serves as a bridge for canal visitors.
Swallows love to perch on the old aqueduct and to swoop over the creek's waters, feeding on insects.
Just upriver the canal bed itself opens into a broad pond, which is often full of life, from frogs, water snakes, and beavers to Green Herons and Osprey. Years ago there were many standing dead trees in the water that were regularly visited by Prothonotary Warblers and Red-headed Woodpeckers. These trees have mostly fallen, and these two species are seen less frequently, but the surrounding wet woods fill with birds at every season. Beyond the ponds are remnants of an old sandstone quarry that supplied the stone for the Smithsonian Castle. The Potomac River's floodplain becomes exceptionally broad a few miles west of Seneca.