ABSTRACT: This study evaluated the environmental impact on water quality in a small-scale trout farming facility. The parameters measured were pH, dissolved oxygen (DO), total dissolved solids (TDS), total suspended solids (TSS), color, turbidity, biochemical oxygen demand (BDO5), ammonia nitrogen (N-NH4), nitrate (N-NO3), nitrite (N-NO2), and thermotolerant coliforms. The quality of the water after being used by the farming facility did not exceed the values measured upstream. The physical, chemical and microbiological analyses of the water showed that trout activities do not significantly affect the water quality when compared with the upstream and downstream sampling points of the fish farm. Results showed that the water load used on the trout farm was 148 m3 kg-1, similar to values observed worldwide. The flow rate used by the trout farm, along with a conventional decantation system, were responsible for maintaining the water quality. In general, the results indicate that small trout farming facilities can be attractive from an economic point of view, with low environmental impact.