This water sits on the soil and slowly evaporates. As the water evaporates, salts concentrate in the soil and rise to a concentration that prevents any plant from growing. In the northern portion of the marsh, the water flows out rapidly, and salinity remains low. This part also does not drain, but since the water is constantly being replaced, the salinity is low. This creates shallow, constantly flooded conditions that cattails thrive in.
Cattails grow so rapidly that they threaten to exclude other plants.
While cattails provide cover, the expanse of a single species will limit the habitat conditions. This year the marsh started its new flooding and draining regime. New tide gates allow a larger volume of water to flow in and out of the marsh during a tide cycle and the gates allow complete draining of parts of the marsh. Three gates will close as tides rise on their downstream side and open as tides subside on their downstream side. This prevents salt water from entering the upstream sections of the marsh.