The present contribution describes the variation of aquatic macroinvertebrates drift and coarse particulate organic matter (MOPG) during a daily cycle in two stream sections of the western mountain range in Narino, Colombia. A total of 1012 individuals were collected (total abundance). The greater abundance corresponded to Ephemeroptera with 422 individuals. Drift density of aquatic macroinvertebrates in the first section (first order river) was superior in hours of the day and the drift of MOPG was larger at night. The drift density of aquatic macroinvertebrates in the second section (second order river) was superior at night and the drift of MOPG was larger in the morning. Approaching the river as a system of causal interactions between the physical envrionment and the communities and between the organisms that conform them, we within the framework interpreted our observations of reference to the current theory of ecosystems present/display.