The objective of this research is to develop a macrophyte model for the growth of submerged aquatic vegetation in the Condoriri River. The processes included in the macrophyte model are: photosynthesis, dark respiration, excretion and non-predatory mortality. The influence of the nutrients, the discharge, solar radiation, and the water temperature on the growth of the aquatic plants was considered. Macrophyte biomass and the specific nutrient transport of TN (0.02 g·s -1 ·km -2 ) and TP (0.0035 g·s -1 ·km -2 ) were greater during the wet season than during the dry season. Good agreements were achieved between field measurements and the model predictions of macrophyte biomass. The proposed model predicted seasonal changes in the growth of the aquatic plants, despite their high spatial and temporal variations.