This study was carried out to determine the water environmental parameters as risk factors for rainbow trout breeding and rearing farms in the Haraz River. 84 water samples were collected at 6 stations during seven months in 2017-2018. Water samples were analyzed by standard titration and spectrophotometry. Results showed that the range of water  temperature (4.0-17.0^◦C), weather temperature (5.0-28.0^◦C), dissolved oxygen (7.36-14.24 mg/l), BOD₅ (0.20-20.80 mg/l), COD (3.50-41.40 mg/l), electro-conductivity (345-650 µS/cm), turbidity (2-81 NTU), TSS (0.01-0.72 g/l), pH (6.98-8.15), TP/P (0.01-0.15 mg/l), PO₄^3- (0.01-0.20 mg/l), NH₄⁺ (0.02-0.31 mg/l), NH₃ (0.14-4.36 µg/l), NO₂^- (0.01-0.21 mg/l), fecal coliform (9-30000 CFU/100ml) and water quality index (48.5-98.5) were changed. The results of the stepwise regression analysis indicated that the risk factors of water quality in the Haraz River were fecal coliform, phosphate, turbidity, and BOD₅ parameters, and fecal coliform had a higher coefficient factor (beta coefficient) than other parameters (p<0.05). As a result, according to the average water index of stations (less than 55), water of the Haraz River is contaminated and critical to breeding and rearing trout, but it has acceptable microbial count for fish farming and wildlife. In addition to seasonal conditions such as environmental conditions and rainfall, the way of pound managing has been effective in maintaining water quality.