The water crisis and the degradation of surface water resources through pollution, combined with the progressive increase in consumption has made it necessary to search for alternative sources of supply.. Because it is a finite natural resource, water is a public good that needs to be allocated among different uses and has its integrity compromised by factors such as industrial development, rapid urbanization and population growth. Considering these issues recognize and evaluate the potential of local water resources is necessary, since the River Inhandava is inserted in the north-northeastern state of Rio Grande do Sul, in the Uruguay river basin and watershed belongs to Apuaê-Inhandava. The objective of this research was to perform the modeling of surface water quality of the River Inhandava-RS. The data were inventoried quality of studies conducted in Rio were considered diffuse agricultural loads, animal waste and sewage. To assess the water quality of the Rio Inhandava, the computer model was used QUAL2Kw. The water quality has been shown, for most parameters, according to Resolution CONAMA 357/2005. The calibrated model QUAL2Kw, became an instrument to in the management of water resources, since the analysis of the results showed the selfpurification in downstream river study.