MATAGORDA BAY. Matagorda Bay (at 28°38' N, 96°15' W) is a major bay on the Texas coast protected from the tides and storms of the Gulf of Mexico by the Matagorda Peninsula. The bay is divided almost equally between Calhoun and Matagorda counties. Tres Palacios Bay, Turtle Bay, Carancahua Bay, Keller Bay, Cox Bay, and Lavaca Bayqqv all open into Matagorda Bay. Matagorda Bay is also crossed by the Gulf Intracoastal Waterway and the ship channels to Palacios, Port O'Connor, and Port Lavaca. All of these channels have spoil banks alongside. The only entry to Matagorda Bay from the Gulf is through Cavallo Pass at the southern end of Matagorda Peninsula, or the Matagorda Ship Channel. At the north end of the bay an isthmus formed by Egret Island and the extended banks of the Colorado River connect the mainland to Matagorda Peninsula and separate Matagorda Bay from East Matagorda Bay.