Water samples were collected from Wisniowka river in 2006 (every month, 2 sampling points before and after fish hatchery) and analyzed for pH, suspensions, BOD as well as ammonia N, nitrates(III), P, Fe, Zn and Cu contents. The monitoring showed the decreased water quality in respect to suspension, nitrate(III) and total P contents. The differences in water quality above and below fish hatchery were negligible. Seasonal variability of the water quality was established.