CoastWise Program

Traditional practices for designing tidal road crossings don't often adequately address the unique complexities, uncertainties, risks, or benefits associated with tidal environments. CoastWise provides a voluntary set of best practices, decision-making tools, and path for designing safe, cost-effective, ecologically supportive, and resilient tidal crossings.

The Challenge of Coastal Road Crossings

Safe, dependable roads are essential to Maine’s economy, access to critical services, and the coastal way of life valued by residents and visitors. Yet maintaining this infrastructure is increasingly difficult for communities across the state especially in coastal areas facing rapid change from accelerated sea level rise. At more than 800 locations where roads cross tidal wetlands, these challenges become significantly more complex.

Tidal wetlands provide coastal storm and flood protection, pollutant filtration, fish and wildlife habitat, commercial harvesting opportunities, and recreation. Salt marshes and other wetlands also store atmospheric carbon that would otherwise contribute to sea‑level rise and other climate shifts. To sustain these benefits, wetlands must remain healthy and resilient, which requires unimpaired tidal flow. However, roughly 90% of Maine’s tidal road crossings restrict tidal exchange. These restrictions place wetlands at risk and increase the likelihood of road flooding, higher maintenance costs, and disruptions to emergency access. 

CoastWise Principles

Tidal wetlands are dynamic systems influenced by a wider range of interacting social and environmental factors than most non-tidal streams. Tidal road crossings require a design approach that adequately addresses complexity and risk, now and for the future.

Key principals of the CoastWise approach include:

• Know your tidal crossings: Learn which crossings are tidal now or likely to be in the coming decades; use the Maine Coastal Program's Tidal Restriction Atlas and other available tools.
• Ask for advice: Contact a CoastWise Technical Partner (listed below by region) to help with project planning, connecting with the right resources, and providing other support.
• Engage qualified engineers: Crossings that effectively manage risk and provide the greatest resilience benefits require engineers skilled in tidal hydrodynamic modeling.
• Encourage local participation: Crossing design involves value judgements having lasting impact. A transparent, participatory design process facilitates outcomes that serve communities best.
• Start with Sea Level Rise: Objective, risk-based selection of a sea level rise scenario early in the project process provides the necessary foundation for all subsequent work.
• Identify Low-lying Features of Concern: Understanding the flood vulnerability of severely damaged wetlands, private property, the built environment, and resource uses is essential for managing risk.
• Establish clear objectives: Early development of clear, measurable crossing performance objectives streamlines the design process and avoids costly design revisions.
• Size crossings for resilience: Keeping pace with sea level rise requires tidal wetlands to experience the full ebb and flow of the highest tides throughout the life of the crossing. 

Learn More about CoastWise

Downloads are PDF files less than 1 MB in size unless otherwise indicated and may require free Adobe Reader software (download here) to view or print.

• Coastwise Approach for Tidal Crossing Design (PDF, 7.3 MB)
• CoastWise Overview (PDF, 1.9 MB)
• CoastWise Topic 1: Selecting a Sea Level Rise Scenario (PDF)
• CoastWise Topic 2: Establishing Crossing Project Objectives (PDF)
• CoastWise Topic 3: Modeling for Crossing Design Evaluation (PDF)

Interested in a CoastWise training? Find more information about upcoming road crossing workshops on Maine Audubon’s website. 

Contacts

For information about the CoastWise Program, please contact Jocelyn Runnebaum, jocelyn.runnebaum@maine.gov. For technical support on individual crossing projects, contact any of the providers listed below according to their service areas. 

Statewide

Erin Campbell
Project Manager
Maine Coastal Program 
erin.grace.campbell@maine.gov
207-592-5689

Bill Bennett
Fish and Wildlife Biologist
Gulf of Maine Coastal Program
U.S. Fish and Wildlife Service
william_bennett@fws.gov
207-781-8364 x15

Southern Maine

Jacob Aman
Project Manager
Wells National Estuarine Research Reserve
jaman@wellsnerr.org 
207-646-1555 x112

Casco Bay

Matt Craig
Habitat Program Manager
Casco Bay Estuary Partnership
matthew.craig@maine.edu 
207-228-8359

Downeast

Jeremy Gabrielson
Senior Conservation Planner
Maine Coast Heritage Trust
jgabrielson@mcht.org 
207-607-4587