Tidal marshlands in the upper estuary ecotone provide essential habitat for juvenile salmonids. In this environment, salmonids grow rapidly and acclimate to saltwater. Worldwide, tidal marshes have been diked and drained to provide agricultural and residential land. Tide gates are one-way doors integrated into dike systems that prevent saltwater flooding and allow upland drainage to the estuary during low tide. By preventing tidal exchange, tide gates have significant upstream effects on water temperature and chemistry, plant and animal community structure, and geomorphology.