The purpose of the work was to determine the impact of using quality test on the evolution of water quality in Lakes Basin. The studies covered three tanks along with their drainage basins (the direct and total) in the city of Szczecin. In order to determine the impact of the estimated load of nitrogen and phosphorus compounds, reaching the Lake from the direct catchment area (as rafting area) and the total (as the supply of courses). The received loads of phosphorus were compared with the limit and dangerous cargoes for the test tanks. The work also assessed the impact of the natural resistance of the water catchment area of the lakes to the degradation caused by the pace of delivery to them.