In order to assess the water quality of La Plata river using aquatic macroinvertebrates, three representative stations were selected: 1.UPTOWN where La Plata river begins, in the interception of Loro river with Aguacatal River. The middle area, which is influenced by streams, rural dumps, paddocks; 3. The lower part where municipal, Battalion Jose Vicente de la Roche y Flores N° 9 and slaughterhouses wastes are discarded. In order to collect macroinvertebrates, twelve samplings were taken per each station into two different periods (warm and rainy) between May and August 2016 by using the methodology BMW/ col. In total 2235 macroinvertebrates distributed in 9 orders, 17 families and 22 genera, they were collected to establish water and physical quality characteristics such as: temperature, conductivity, dissolved oxygen, pH, turbidity, salinity, TDS and COD were determined . Finding that oxygenation is abundant due to environmental capacity and turbulence caused by the presence of large rocks, which in turn allow the diversity of aquatic macroinvertebrates, parameters such as turbidity, conductivity, TDS, salinity, and temperature increase downstream river, while the pH remains constant and COD exceeds all seasons the 91mg / l which shows the presence of contamination across the river. This information relates to that obtained with the BMWP index in which class IV for the three study stations is obtained, which refers to contaminated water, just as wanting to achieve greater accuracy the ASPT index was applied, obtaining for the top and middle, class II, which corresponds to slightly polluted waters, and class III for the bottom, indicating dubious quality that is moderately polluted waters. Therefore it is concluded that the two indexes indicate the presence of pollution which increases downstream, and is supported with the physicochemical parameters. This river on a general level is subject to contamination of rural and urban agricultural origin, which limits their conditions of use.