Most of the land within the ACE Basin is protected either through conservation easement, wildlife refuge, federal ownership, or whatever.  The eponymous rivers are the Ashepoo River (middle), Combahee River (southernmost), and Edisto River (northernmost).

While not within the ACE Basin, this map includes the upper reaches of the three rivers and their tributaries.  Until I visit all of these landings, I'm sure that mistakes abound.

Near the ocean, the North Fork of the Edisto River forms the northeastern boundary to the ACE Basin.  The river begins as the Edisto River North Fork and South Fork before merging into the Edisto Mainstem near Branchville, SC.