The Texas Chenier Plain Initiative Area is a rich and complex mixture of wetlands, uplands, and open water that extends roughly 200 miles from Sabine Lake at the Texas-Louisiana state line to Galveston Bay (see map). It runs from the expansive coastal marshes bordering the Gulf of Mexico shore, inland for 40 to 70 miles through the coastal prairie into areas of intensive rice cultivation.

Geographically it includes the the Texas counties of Chambers, Jefferson, Orange, and Liberty. Very small portions of Galveston and Harris Counties are also included at the western edge of the Texas segment.