the dams would be built with the intention of lowering the water level in long island sound, not raising it. the turbines creating electricity would never stop turning and the whole area would benefit.
won't lower the water level. Only pumping the water away or evaporation will lower the water surface below sea level. If there's enough rain and snow draining into the area between the dams to keep up with evaporation the ONLY
way to lower the water level would be to pump the water out, which would use more energy than would be generated when you let water back in (which would fill the area back up to sea level again).