The Effects of Tide Gates on New England Wetlands and Other Tidal Resources

Abstract

Tide gates are structures used to protect personal property, agricultural land, and public infrastructure from flooding due to extreme tides and storm surges by restricting tidal flow to intertidal, shallow subtidal, and brackish estuarine environments. However, these structures can result in impacts to marine, estuarine, and tidal riverine resources, including but not limited to resident fish and shellfish, diadromous fish, coastal marshes, seagrass, macroalgal and shellfish beds, mudflats, and tidal creeks. Tide gates can restrict access to fish and invertebrates to and from habitats important for feeding, spawning, predator avoidance, and migration, and can alter environmental conditions that can impact individual fitness. Tide gates can also interfere with physical and chemical dynamics such as nutrient and sediment flux, which are critical factors in marsh building processes. In addition, the increasing effects of climate change, including sea level rise and more extreme precipitation patterns, will amplify many of the adverse effects of tide gates. There are likely several hundred individual tide gates in use throughout New England, although a comprehensive, regional inventory and assessment of tide gates has not been conducted. Many of the known tide gates are in various states of disrepair, and lack appropriate operations and management plans. It is likely many unreported tide gates exist in the region and a subset of those are similarly inoperable and restrict tidal exchange. This paper describes the types of tide gates commonly found in New England coastal areas and the various physical, chemical, and biological impacts associated with them. We have included a series of recommendations that regulatory and policy makers should implement to reduce the long-term and chronic impacts of tide gates in New England coastal areas.