The paper results of a study on general chemical indicators of surface water quality carried out in Roztoka Odrza?ska in 1982-1994.The parameters in question were: oxygen content, chloride, nitrate and dissolved phosphate concentrations and BOD5. An attmept was undertaken to determine the influence of the Odra River flow on the chemical status of Roz-toka water. Threshold values of Qs were determined in three regimes of water transport: a back flow of water from the Szczecin Lagoon in the full river-bed and bidirectional (two-layered) water movements - with back flow prevailing and with riverine inflow prevailing.