Wetlands need variable levels
Fluctuating water levels are necessary to maintain dynamic, diverse and healthy coastal wetlands. Cycles of high and low water levels create diverse wetland vegetation that is more resilient to other stresses put on the system. Occasional high water levels reduce invasion of upland woody plants, helping to increase meadow marsh at upper elevations. Occasional periods of sustained low water levels allow seeds in the lake bed to germinate, establishing many emergent wetland plant species. Low lake levels also suppress invasion of meadow marsh by moisture-requiring cattails, again increasing meadow marsh. In fact, the patterns of water-level change are the driving force that determines the overall diversity and condition of wetland plant communities and the habitats they provide for a multitude of invertebrates, amphibians, reptiles, fish, birds, and mammals.