The contribution deals with a nutrient pollution process represented by nutrients - ammonia, nitrogen, nitrates and phosphates on the Bystřička River, the small watercourse. The research was carried out on the watercourse section 3,75 km long below the village Suchá Loz. The village has 1093 habitants and does not any have sewage water treatment plant. Four nutrient pollution-sampling profiles were selected on the watercourse. The measured values are used for simulations of dissolved oxygen process in tthe longitudinal profile of the stream (en)