The Algodonal River is one of the most important bodies of water in the department of Norte de Santander. Could a study of the biodiversity of insects associated with the Algodonal River basin determine the quality of the water that is being purified downstream in the municipality of Ocaña? For this study, three sampling stations were taken in the river basin. Transepts of 100m x 20m, 2000 m2 per station were sampled. The collection was carried out with hand, manual, water net and pitfall traps. Seven orders were collected per station: Hymenoptera, Coleóptera, Hemíptera, Homoptera, Diptera, Ortóptera and Odonata, with a total abundance of 431 individuals. Seven bioindicator families were found: Curculionidae, Veliidae, Libelulidae, Coenagríonidae, Gelastocoridae, Muscidae and Culicidae, whose importance values ​​allowed the water to be classified as class IV or of doubtful quality, which indicates that it is contaminated. Parameters were evaluated physicochemicals in situ, dissolved oxygen 5.23 - 7.57 mg / L, PH 7 - 8 and Conductivity 31.8 - 55.4 µS-cm, which supported with tests of total hardness (mg / L), Chlorides ( mg / L), Total Alkalinity (mg / L) and NTU Turbidity, determined that the quality of the water is doubtful and that for its consumption it must be made drinkable.