In one of the most recent studies for AGPL, Hydronamic studied the influence of works in the outer bar on the salinity-distribution in the upstream section of the estuary. The main conclusion from this study was that current-patterns, tidal prism, etc. in the inner estuary are :fully determined by ,the geometry of the Corredor, and that consequently the influence of civil engineering works west of Belem on the salinity distribution are negligible. Although it was not studied, it became obvious that works east of the Ponte de 25 Abtil may have an impact on on the salinity distribution. This impact may be considerable. In this memorandum some general aspects of impacts on the salinity distribution are discussed, as well as those aspects which should be studied by AGPL before and after permission is given to construct important works in the area.