The Salt Marsh Advancement Zone Assessment for Connecticut

Adam Whelchel
Posted on: 10/05/2015 - Updated on: 3/02/2020

Posted by

Adam Whelchel

Project Summary

The Salt Marsh Advancement Zone Assessment for Connecticut report is the culmination of a statewide study of each of the 24 coastal municipalities in Connecticut. At the municipal scale, these 24 individual reports inform communities about future marsh advancement locations, current land use of those affected properties, and which parcels are critical to the persistence of the community’s salt marshes. The state-level salt marsh advancement assessment highlights the top critical parcels for conservation in order to maximize the benefits of Connecticut’s natural infrastructure into the future. Additionally, this report provides data that can be used to inform long-term coastal natural resource planning in the context of overall risk reduction and resiliency improvements across the state’s coastline. This is the first time such parcel-scale, specific information has been available and is designed to provide decision makers and stakeholders with the following:

  • Where and how much salt marsh advancement occurs on existing open space (refuges, parks, preserves, etc.) and will require progressive management;
  • Where and how much salt marsh advancement occurs on currently unprotected and undeveloped parcels; and
  • Where and how much conflict there will likely be in the future between the existing built environment (roads, airports, schools, neighborhoods, businesses, etc.) and daily tides.


In 2006, The Nature Conservancy established the Coastal Resilience program that provides tools and a solution framework to reduce the ecological and socioeconomic risk of hazards and comprehensively improve community resilience over time. The program focuses on helping decision-makers explore locally relevant, downscaled flooding scenarios from sea level rise and/or storm surge; analyze the potential ecological, social and economic impacts of each scenario at a local, regional, and state scale; and identify solutions to address these issues. Since 2006, The Nature Conservancy has assisted many coastal and inland communities in Connecticut by providing this critical information and a comprehensive, community-based process that improves overall resilience and sustainability.

There is a near-universal recognition by coastal and inland communities in Connecticut and elsewhere that natural infrastructure – such as wetlands and forests - is a cost effective, long-term part of the solution that will protect people, infrastructure and natural systems from extreme weather and climatic change. In order to maintain this natural infrastructure it will require 1) routine and ongoing management activities as well as the restoration of degraded areas, 2) forward-looking planning to accommodate changes in habitat composition and location due to climatic change and 3) enforcement, modification and/or establishment of new land use policies and growth strategies. Opportunities also exist to account for and integrate the services or co-benefits provided by natural infrastructure via new development, redevelopment, or realignment activities.

Sea level rise and the impacts of flooding have and will continue to alter the presence and abundance of natural infrastructure in Connecticut. One of the most noticeable changes is occurring at the coastal edge where salt marsh is in the process of advancing upslope into areas now considered uplands. In order to clearly identify where this will occur along Connecticut’s coast, The Nature Conservancy created the Salt Marsh Advancement Zone Assessment project to assist with future planning for natural infrastructure in the context of overall risk reduction and resiliency improvement for coastal communities.

The Salt Marsh Advancement Zone Assessment project uses a salt marsh advancement model developed for the Coastal Resilience program to provide a useful municipal and state level tool for long-term management of natural infrastructure. The project goals include providing useful information to the state, towns, private property owners, non-profit organizations, and others to improve immediate and longer-term management of natural infrastructure that will also help to reduce hazard risk and improve resilience across Connecticut and beyond.


This report is the culmination of a multi-year effort to complete salt marsh advancement zone assessments for every coastal municipality in Connecticut. Those assessments, as well as the statewide report featured in this case study, use a salt marsh advancement model developed in partnership between TNC and the University of Connecticut’s Department of Natural Resources Management and Engineering in 2009. Data from this model was analyzed to provide planners key information for long-term coastal natural resource management. Specifically, the report shows where salt marshes will be advancing and which properties, both protected and unprotected from development, are most critical to the accommodation of future marshes. The municipal-level assessments also define at the parcel scale the vulnerabilities to the built environment over time. Currently, the reports and maps are being transferred to elected officials, staff, and land trusts via outreach events and workshops to ensure parcels for salt marsh advancement and parcels with high vulnerability to critical structures from sea level rise are properly factored into short- and long-range visioning of Connecticut's coast.

Outcomes and Conclusions

The principal conclusions from this study indicate that for the entire coast of Connecticut:

  1. Over 29,600 parcels across the 24 coastal municipalities provide some area suitable for salt marsh advancement;
  2. Approximately 5,620 acres of future salt marsh advancement are located on protected parcels (federal lands, state and municipal parks, private nature preserves, etc.);
  3. Approximately 11,272 acres of future salt marsh advancement are located on “unprotected” parcels (non-conservation/open space lands); and
  4. Approximately 7,037 acres of currently built-up areas (parking lots, schools, churches, airports, etc.) will be in daily conflicts with tides, without action, in the future.

These conclusions are now being communicated to local decision makers to help assist with proactive adaptation to protect future marsh zones and critical facilities currently in harm’s way. The transfer of this information is being enhanced by the availability of both the salt marsh advancement zone layers as well as parcel layers for all 24 coastal municipalities are provided on the Coastal Resilience tool - a free, web-based mapper that allows for ongoing visualization of salt marsh advancement and vulnerability of critical facilities at the parcel scale among other features.

All 24 Salt Marsh Advancement Zone Assessments and the cumulative Connecticut Coast report are available for download at


Whelchel, A. (2015). The Salt Marsh Advancement Zone Assessment for Connecticut. Ed. Rachel M. Gregg [Case study on a project of The Nature Conservancy and partners]. Retrieved from CAKE: (Last updated October 2015)

Project Contacts

Position: Director of Science

Affiliated Organizations

The Nature Conservancy is the leading conservation organization working around the world to protect ecologically important lands and waters for nature and people.