Now the Grevelingen was closed a great lake was created. But they wanted to have salt water in this lake so refreshing with sea water by a sluice was needed. They decided to make a sluice in the Brouwerdam. The final stage started with constructing this sluice in 1978. This sluice was constructed in the central part of the dam by making two circular dikes and creating a constructing pit. After making the sluice the dikes were removed an the sea water could flow in and out the Grevelingen.