 Both rivers yield similar volumes on average, but the Mopan watershed is less mountainous than the Macal watershed, giving it less intense flood waves.The combined Mopan River/Belize River watershed contains 11% of the population of the Peten District in Guatemala and 45% of the population of Belize.These populations depend on the river for drinking water and other domestic uses; however, water quality is degraded from sediment, nutrient loading, untreated sewage discharge, pesticides and other toxins.