 The headwaters and upper basin comprise about 1000 square kilometers and rest in the southern Maya Mountains, whilst the lower basin is known as the Mountain Pine Ridge 
catchment.The soils in the upper watershed tend to be shallow and rocky, leading to rapid runoff.All of the upper catchment tributaries join the mainstem channel considerably before Guacamayo, the approximate join point of the two connecting sub-sheds of the Macal River.