Christmas Bay is a minor estuary located southwest of the Galveston Bay system on the upper Texas coast. Key Features in the Christmas Bay system are Bastrop Bay to the north and Drum Bay to the south. This minor estuary is protected from the Gulf of Mexico by Follet's Island, although a connection with the Gulf of Mexico exists through Cold Pass and San Luis Pass. Bastrop Bayou is the main source of freshwater inflow to the system, in addition to runoff from surrounding coastal watersheds. The bay system is surrounded by Brazoria County, and is affected by planning activities in the Region H Water Planning Group.