Piney River (Nelson County) - 1.) The "Big Piney" (Alhambra to VA. 827 ['Perkins Mill Rd'] Woodson) (VA)
400 to 450 is a good guide to minimum flow. The upper range of flow will, of course, vary depending on individual groups' skill level and disposition.
The longest and most complicated of the bigger drops. Can enter either the right channel that ends in a boof or the skinny left channel. Either way, end up in the river left eddy after the channels converge. Then run the complicated river left bouder garden to finish up the second part of the rapid.