COPANO BAY. Copano Bay, just west of Rockport off Refugio and Aransas counties, is a twelve-by-six-mile extension of Aransas Bay (at 28° 07' N, 97° 07' W). The bay was first explored in 1766 by Diego Ortiz Parrilla,^qv who named it Santo Domingo, but after the port of Copano was established in 1785 and named for the Copane Indians in the area, the bay became known as Copano Bay. The surrounding flat, marshy terrain is surfaced by sand and dark clays that support mesquite and grasses.