Maine Tidal Restriction Atlas

The Maine Coastal Program and our partners created the Tidal Restriction Atlas for communities, road owners, conservation groups, and others who plan for coastal resilience. The Atlas is based on the Maine Coastal Program's statewide Tidal Restriction Assessment, the first dedicated review of tidal structures in decades. The Atlas helps people identify culverts, bridges, dams, and other structures that are currently tidal or will likely become tidal in the future. The Atlas is intended to complement The CoastWise Approach for tidal road crossing design. 

A culvert with water and powerlines on a blue sky day.
A culvert in Addison, Maine.

Mapping to Support Climate-Resilient Decision Making

Healthy tidal wetlands provide storm and flood protection, pollutant breakdown, wildlife habitat, and commercial and recreational value, while salt marshes also store atmospheric carbon that would otherwise accelerate sea‑level rise; yet roads, dams, and other structures that restrict tidal exchange limit the delivery of saltwater and sediment that wetlands need to remain resilient, and in Maine, where about 90% of tidal road crossings restrict the tides, these impaired crossings not only weaken wetland health and adaptability but also wear out prematurely as rising seas increase tidal volumes, driving up maintenance costs, accelerating replacement schedules, and threatening reliable access to critical services.

The Tidal Restriction Atlas shows where roads, railroads, dams, and other structures cross tidal streams, marshes, and other tidal wetlands. The Atlas allows you to learn about:

  • Crossings that are presently tidal or likely to become tidal in the coming decades
  • Crossings that are tidal restrictions
  • Information for individual crossings or multiple crossings selected using data table filters
  • Crossing structural dimensions, condition, and site photos, where available
  • Ecological features like fish and wildlife habitats associated with individual crossings
  • The extents of tidal influence projected under Highest Astronomical Tide and sea level rise scenarios 

View Map Full Screen

For more information contact Devin Domeyer, devin.domeyer@maine.gov. 

Additional Resources

Contributors to the Maine Tidal Restriction Atlas Development

  • Casco Bay Estuary Partnership
  • Great Bay National Estuarine Research Reserve
  • Kennebec Estuary Land Trust
  • Maine Coast Heritage Trust
  • Maine Dept. of Transportation
  • Maine Geological Survey, Maine Dept. of Agriculture, Conservation, and Forestry
  • Midcoast Conservancy
  • Natural Areas Program, Maine Dept. of Agriculture, Conservation, and Forestry
  • The Nature Conservancy
  • New Hampshire Department of Fish and Game
  • US Fish and Wildlife Service
  • US National Oceanic and Atmospheric Administration
  • Wells National Estuarine Research Reserve