Phosphorus forms in the water - suspended particles - bottom sediments system from the Nistru river. The samples of water, suspended particles and bottom sediments collected during the summer of 2004 from the Dubasari Reservoir (Oxentia station) and Nistru River (Vadul-lui-Voda station), were analized. For the determination of phosphorus forms the World Health Organization recomandations were used. The content of both inorganic and organic phosphorus in bottom sediments is considerably higher than in suspended materials. Lab modeling showed that about 1 - 27% of total quantity of phosphorus can be desorbed from bottom sediments. Thus, Nistru River bottom sediments can become an important source of phosphorus as fertilizer.