This study focused on the macroinvertebrate population in the upstream waters of Lake Buyo. Data collection was carried out in 4 stations (G1 to G4) from November 2017 to October 2018. Sampling involved both physical-chemical parameters and macro invertebrates. Physical and chemical parameters (temperature. dissolved oxygen. pH and conductivity) were measured in situ using a multi-parameter at each sampling campaign. Water samples were taken for the subsequent determination of nutrient salts (nitrate. phosphate. ammonium). Macro invertebrates were collected using a dip net and a sediment bucket. The physico-chemical characterization of Guessabo Bay showed that the abiotic parameters vary little from one station to another. The inventory of macro invertebrates in the water body yielded 98 taxa divided into 59 families. 16 orders and 07 classes belonging to insects. gastropods. bivalves. crustaceans. Arachnids and Oligochaetes. Insects were found to be the most diverse class. followed by the class of molluscs. The values of Shannon Weiner's diversity index and Pielou's equitability showed that the aquatic macroinvertebrate population of the lake is more or less diverse and balanced. which reflects good water quality. Jaccard's similarity index reveals a high degree of similarity between G1 and G3. The distribution of aquatic macro invertebrates in this lake is positively influenced by the environmental variable conductivity. nitrate. phosphate. ammonium. pH. dissolved oxygen and temperature.