The purpose of the study was to evaluate the increase in diameter in the arboreal component of plots located along the Chiriquí River. Different activities use river waters including power generation. Five fixed plots of 500 m2 were established between the mouth of the Caldera River and the Experimental Station of the Faculty of Agronomy of the University of Panama at the level of the inter-American highway. The plots were visited regularly and all trees with DAP> 25 cm were measured. The average growth for all plots was 0.86 cm year-1 with maximum values at the Chiriquí dam (1.30 cm year -1) and the lowest at Los Cerritos (0.31 cm year-1) downstream the dam. This area receives the first impact of reduced flow that occurs at the level of the Chiriquí dam. The need arises to review the ecological flow available for riverine vegetation at different periods of the year, especially in the summer.