Copano Bay is a northwestern extension of Aransas Bay, west of Rockport, Texas in Refugio and Aransas counties. It is supplied with seawater from the Gulf of Mexico via Aransas Bay, and fed freshwater from the Aransas River, Mission River and Copano Creek. As an estuary, the bay is home to a diverse ecosystem consisting of various birds including the endangered whooping Crane, and numerous finfish including the redfish as well as shellfish such as oysters. It is classified as a nursery for shrimp, which prohibits production from the bay. Copano Bay is also an historic location for human usage and settlement that dates back to the 18th century, beginning with the historic port of El Copano and the 19th century settlements of St. Mary's of Aransas and Copano.
Copano Bay was inhabited by the nomadic Aransas Indians, who constructed camps along the shore, 4,000 years ago. The Aransas people left the area approximately 700 years ago, and were replaced around 1400 CE by the Copane Indians, for whom the bay is named. The Copane were one of five groups making up the Karankawas, hunter-gatherers who occupied the mid-Texas coast.