Project Summary

The Maine Coast Heritage Trust (MCHT) developed the Marshes for Tomorrow (MfT) project to examine the extent of potential marsh migration under a one-meter sea level rise scenario. The maps developed showed that a one-meter rise in sea levels would result in approximately 10,000 acres of marsh moving onto currently undeveloped, unprotected land parcels. The MCHT is now helping land trusts and other conservation organizations focus on coastal land protection priorities using the maps and other technical guidance.

Background

Much of the central to northern Maine coast has rocky or unconsolidated bluff habitats with a relatively high level of natural resilience. Conversely, coastal dune beaches and tidal marshes are much more vulnerable to sea level rise. Many of these vulnerable areas are located in the southern portion of the state where development pressure is especially high. In 2014, the MCHT Board, as part of its strategic plan update, examined the threats and impacts of climate change and sea level rise on land conservation in coastal Maine.

Implementation

The MCHT undertook a two-year modeling and mapping process to understand how marshes are expected to migrate landward with rising sea levels. The mapping process incorporated state-developed data on marsh extent and elevation and a one-meter sea level rise scenario to show the expected future extent of marshes and marsh buffer areas. These future marsh areas were overlaid with an unprotected land layer to highlight opportunities for land conservation. Maps showed that a one-meter rise in sea level rises would result in approximately 10,000 acres of marsh moving onto undeveloped, unprotected land parcels. The MCHT developed public-facing maps showing priority lands for marsh migration protection. The MCHT is also working with other partners to identify dams and other tidal barriers whose removal can restore marshes and increase aquatic connectivity to keep priority marsh ecosystems functioning.

The MCHT works with many partners to implement the land acquisition portion of MfT, including the Maine Natural Areas Program, U.S. Fish & Wildlife Service, land trusts, and other conservation organizations. The MCHT also works with the Maine Coastal Program, the Maine Chapter of The Nature Conservancy, and other partners to prioritize and remove tidal barriers to restore marsh function.

Outcomes and Conclusions

This project developed a set of public-facing maps highlighting the best potential places for tidal marsh migration, and provides guidance to land trusts, municipalities, and managers to understand how to incorporate marsh migration into their coastal resilience planning and implementation processes. The initiative has also provided planning maps and outreach training for land trusts to help them communicate with landowners to protect marsh and marsh buffers. To date, the MCHT has protected more than 1,600 acres of marshland in Maine and is developing and refining stewardship practices to share with other coastal land trusts, environmental organizations, and local municipalities. Looking ahead, MfT partners are developing an atlas of tidal crossings for use by land managers. The MCHT continues to seek new ways to share information and resources with land trusts to catalyze tidal marsh conservation.

Citation

Sims, S.A. (2021). Marshes for Tomorrow Initiative in Coastal Maine [Case study on a project of Maine Coast Heritage Trust]. Product of EcoAdapt’s State of Adaptation Program. Retrieved from CAKE: https://www.cakex.org/case-studies/marshes-tomorrow-initiative-coastal-maine (Last updated October 2021)