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Risk reduction and resiliency enhancement for the Great Marsh

Chris Hilke
Senior Program Manager and Principal Investigator
Organization information: 

The National Wildlife Federation, US Fish & Wildlife Service, Boston University, University of New Hampshire, Ipswich River Watershed Association, Merrimack Valley Planning Commission, along with many other entities, make up the Great Marsh Resiliency Partnership (GMRP). The GMRP is working to enhance the resilience of the Great Marsh and reduce the vulnerability of neighboring communities.

Key personnel:

  • Taj Schottland, Coastal Adaptation Specialist
    National Wildlife Federation
  • Wayne Castonguay, Executive Director
    Ipswich River Watershed Association
  • Peter Phippen, North Shore Regional Coordinator
    MassBays National Estuary Program/Merrimac Valley Planning Commission
  • Gregg Moore, Research Associate Professor of Biological Sciences
    University of New Hampshire
  • Alyssa Novak
    University of New Hampshire
  • Nancy Pau, Refuge Biologist at Parker River National Wildlife Refuge
    United States Fish & Wildlife Service
Summary / Overview: 

The Great Marsh Resiliency Planning Project takes a holistic and integrated approach to building coastal resiliency by combining natural resource enhancement with community risk reduction on a regional scale. There are five project sub-components working together to reduce community vulnerability in the near term and, through long-term planning, position the communities to make significant steps towards reducing their long-term vulnerability. The five project sub-components include:

  1. Marsh restoration,
  2. Dune restoration,
  3. Hydrodynamic sediment transport and salinity modeling,
  4. Hydro-barrier assessment, and
  5. Community resiliency and adaptation planning.

Located along the north shore of Massachusetts, the Great Marsh is New England’s largest contiguous barrier island and saltmarsh. The marsh provides critical habitat to state and federally listed species, sportfish, shellfish, and thousands of birds migrating along the Atlantic Flyway. The area is also home to 29 municipalities and millions of visitors that benefit from the ecosystem services? provided by the marsh. However, storm surge, sea level rise, and accelerating erosion have contributed to decreased marsh health and increased community vulnerability. As is commonly the case, adaptation planning in the Great Marsh must navigate a complex web of conservation, economic and political priorities, as well as multiple landowners and diverse management values. To address these cross-cutting challenges, the National Wildlife Federation is leading the GMRP in the execution of a $2.9 million dollar project funded by the Hurricane Sandy Resiliency Grants program.

Displayed are maps from the National Wildlife Federation showing areas in the community vulnerable to coastal flooding, both now and in the future.
Displayed are maps from the National Wildlife Federation showing areas in the community vulnerable to coastal flooding, both now and in the future.
Task force working on the Great Marsh Resiliency Planning Project.
Task force working on the Great Marsh Resiliency Planning Project. Image credit: PIE-Rivers


  1. Marsh Restoration: The marsh restoration team, led by the Merrimack Valley Planning Commission (MVPC), treated over 10,000 acres of marsh to remove non-native, invasive Common Reed (Phragmites australis) and Perennial Pepperweed (Lepidium latifolium) as well as invasive European Green Crabs across 1,280 acres. In addition, a team from Boston University (BU) reestablished submerged aquatic vegetation (SAV), including 3 acres of eelgrass in Essex Bay. They transplanted multiple eelgrass populations by hand to build a diverse population that will resist current and future stressors. Initial results indicate the restoration has been very successful, with 80% survival rates.
  2. Dune Restoration: Dunes on Plum Island and Salisbury Beach serve as a protective buffer? for coastal communities, reducing the impacts of sea level rise and storm surge on neighborhoods and nearby infrastructure. After severe erosion and storm damage, there is little or no vegetation to anchor the dune in place in many areas (which leads to even more erosion). To address these issues, the University of New Hampshire and Massachusetts Department of Conservation and Recreation (DCR), as well as local Conservation Commissions and other stakeholders, restored over 20 acres of priority dunes in Salisbury, Newbury, and Newburyport.

    DCR added over 18,000 cubic yards of sand along a one-mile stretch of heavily degraded dunes. A variety of native plant species were selected for their benefit to wildlife and their suitability to dune erosion and accumulation. Plantings and fencing techniques promoted dune stabilization, growth, and resilience. These efforts also included extensive stakeholder outreach and education; dune planting created an opportunity to engage schools and provided a “living classroom” where hundreds of students participated in the restoration work.

  3. Hydrodynamic sediment transport & salinity modeling have enhanced our understanding of sediment transport and erosional forces on barrier beaches, deposition patterns of sediment into marsh and tidal creeks, and of barriers to the natural flow of sediment. Increased understanding of salinity gradients informs management practices to increase the resiliency of natural habitats, such as the control of invasive plants. Scenario planning with this model has allowed managers to assess marsh and riverine restoration options and identify likely long-term effects. Ultimately the model will help pinpoint areas where restoration efforts will have maximum ecosystem-wide benefits.

    4. Hydro-barrier assessments were conducted on more than 1,000 dams, road-stream crossings, and coastal stabilization structures in
        the 29 communities in the Great Marsh watershed. Each structure was prioritized and preliminary designs were made for the top 100
        high-risk or high-impact barriers in the region. With preliminary design blueprints in hand, these communities are poised to remove,
        replace, or retrofit dozens of hydro barriers, with appropriate levels of support.

Great Marsh Resiliency informational brochure.
Great Marsh Resiliency informational brochure.

    5. The community resiliency and adaptation planning initiative targeted the 6
        shorefront communities directly bordering the Great Marsh: Salisbury, Newbury,
        Newburyport, Rowley, Ipswich, and Essex. The planning process included the
        development of cross-sector municipal resiliency task forces, town-specific
        climate vulnerability assessments, community engagement workshops, and
        culminated in a Great Marsh Coastal Resilience and Adaptation Plan (currently in
        draft format). The planning effort incorporated virtually all prior local, state, and
        federal plans that were developed in the geography and recommends over 100
        near- and long-term risk reduction strategies. Strategies include nature-based
        solutions, building retrofits, policy measures, and outreach and education initiatives
        - all of which are operationally feasible and can be implemented in the near to
        moderate term.


This 3 year project restored priority dunes that protect residential neighborhoods and public infrastructure from flooding. Invasive species control and reintroduction of submerged aquatic vegetation are reducing erosion in the marsh and tidal channels, providing important fish and wildlife habitat, and increasing the overall health and resiliency of the marsh so it can provide maximum ecosystem services? to its communities. Communities have preliminary design blueprints to upgrade or retrofit the top 100 high-risk hydro-barriers to reduce flood hazards and restore aquatic connectivity. The six shorefront communities have a draft Great Marsh Coastal Adaptation Plan that identifies shovel-ready risk reduction projects as well as municipal regulations and policies that incentivize climate-smart development and/or prohibit development in hazard-prone locations. In summary, this project reduced community vulnerability, broadened stakeholder engagement, educated decision makers, and increased the health and resilience of the Great Marsh.

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