The paper presents the results of the assessment pertaining to the Przebędowo reservoir, opened for exploitation in 2014, in terms of vulnerability to degradation. The reservoir is located in the catchment of Trojanka River (Struga Goślińska). Trojanka falls into the river Warta at km 218 + 500. The construction of the reservoir was completed in 2014. The surface area of the reservoir is 12.03 hectares and its total volume is 0.162 million m3. The reservoir has an elongated shape, its length is 1450 m and its maximum width is 120 m. In the first stage of the work, the potential inflow of biogenic compounds from the catchment area was analyzed and the reservoir vulnerability to degradation was assessed. In the second stage, the water quality of the Trojka River was evaluated and the nitrogen and phosphorus loads were calculated. Nitrogen and phosphorus loads flowing into the reservoir were compared with the allowable and critical values calculated according to the hydrological model of Vollenweider. This comparison permitted the classification of the reservoir vulnerability to degradation. The Przebędowo reservoir was found to be highly vulnerable to degradation. The obtained results show that this state is mainly due to the geometry of the reservoir: shape, elongated coastline and low average depth. Moreover, a high share of arable land in the catchment area increases the potential risk associated with the inflow of biogenic compounds into the reservoir.