A joint effort between the U.S. Environmental Protection Agency (EPA) and the Federal Highway Administration (FHWA) produced “Tidal Restrictions Synthesis Review” published in 2020 that summarizes the state of knowledge of tidal restriction extent and their potential effects on the coastal environment. The document is organized into the following topics: 1) Type and Abundance; 2) Potential Adverse Effects; 3) Existing Tools to Facilitate Avoidance or Removal; and 4) Recommendations. Tidal wetlands are important coastal habitats that provide numerous ecosystem services and benefits for coastal communities, including nutrient uptake and processing, carbon sequestration, and protection against coastal storms. They also support productive fisheries through the provision of habitat for fish and shellfish as well as ecologically important waterfowl. Along the coasts of the United States, large swaths of tidal wetlands are being lost to development, drainage, erosion, subsidence and sea-level rise at an outstanding rate (seven football fields per hour) every year. As sea levels continue to rise and coastal storms are expected to increase in frequency and intensity, loss of functioning tidal wetlands becomes a more critical issue to address. Tidal restrictions (e.g., dike, berms, levees, ditches, culverts and tide gates) are potentially significant contributors to tidal wetland degradation and loss. Many of these tidal restrictions were put in place specifically to alter site hydrology for agriculture, flood control, mosquito control, or to protect infrastructure, among other purposes. However, some of the most common tidal restrictions are those related to transportation, where altered hydrology is an unintended effect of installed bridges, culverts, and causeways. Furthermore, this document identifies needs and provides recommendations for tidal restriction avoidance and removal when practicable. These recommendations are intended to help state and local transportation departments, state and federal resource agencies, tribes, municipal governments (including planning and flood control entities), their partners, and other stakeholders, take actions to remove tidal restrictions from the landscape.
Enhancing infrastructure systems for net ecological gain