sentences:  Thus the water quality of the Monkey River supports not only freshwater species in the river's upper reaches and estuarine species in the lower reaches, but also the sensitive offshore Belize Barrier Reef.The Monkey River drains much of southern Belize through the Bladen (southern) Branch, which includes tributaries from a part of southern Guatemala and the southern slopes of the Maya Mountains in Belize, containing the ancient Mayan sites of Nim Li Punit and Lubaantun.The (northern) Swasey Branch of the Monkey River rises in the East Basin of the Cockscomb Basin Wildlife Sanctuary, a wilderness area set aside for jaguar preservation.