Managed Retreat Toolkit
Environmental: Wetlands Migration
|Credit: Greg Hoxsie for ReWild Mission Bay.
As sea levels rise, wetlands are encountering physical barriers to inland migration — a phenomenon known as "coastal squeeze." Wetlands are being squeezed between sea-level rise on one side and human development on the other, preventing their natural ability to adapt by moving inland to higher ground. To respond to these threats, there are two primary management responses state and local governments may consider: (1) maintaining existing or restoring coastal wetlands; and (2) facilitating their migration inland.See footnote 2 Each management response raises similar and yet distinct questions that decisionmakers will have to address to enhance wetlands and support their long-term viability. For example, maintaining existing or restoring coastal wetlands and adequate sediment supplies will require that decisionmakers evaluate water management requirements regarding allowable discharges and deposits to government-regulated water bodies (that can restrict sediment flows) and the use of clean fill in wetlands, including from dredging. Allowing the migration inland of wetlands raises different issues, since migrating wetlands may encroach on existing land uses, such as agriculture, forestry, and residential communities. As a result, decisionmakers will need to address additional questions about shifting economies, environmental justice and equity, and wetlands and private development regulations. Ideally, governments will develop comprehensive managed retreat strategies to implement both types of management responses. However, there is deficient information about legal and policy tools that state and local governments can use to adapt to sea-level rise and limit the impacts of coastal squeeze on migrating wetlands. This section attempts to fill that informational gap.
This section first provides a short background on the law and federal, state, and local actors that could impact state and local decisions, including considerations for wetlands on public versus private property. This section then identifies six components of a comprehensive wetland migration strategy as recommended practice tips for state and local coastal governments: (1) data; (2) planning; (3) voluntary land acquisitions; (4) legal tools; (5) community engagement; and (6) funding. This section concludes with case study examples to illustrate each of these six components. While other coastal ecosystems, like forests, and myriad species are also capable of and will need to shift their habitats to adapt to different climate threats, this section focuses on wetlands. This section will be broadened in the future as more on-the-ground actions occur.
It is important to note that, as multiple coastal ecosystems change and encroach on human development, land managers and communities will have to weigh decisions about whether to prioritize the conservation of some habitats or species over others. For example, in Dorchester County, Maryland, the inland migration of salt marshes is killing forests, resulting in a phenomenon known as “ghost forests.”See footnote 3 While sea-level rise may continue unabated, governments and people can take short- and long-term actions that affect the survivability of each habitat. For example, governments could help marshes migrate inland by removing roads or conversely, protect forests by erecting a flood barrier to keep marshes at bay. As people and ecosystems retreat away from the coast, land-use decisions should reflect human priorities for the environment.
A loblolly pine "ghost" forest in Blackwater National Wildlife Refuge in Dorchester County, Maryland (June 2018). Sea-level rise and land subsidence result in brackish water intruding on forested land and killing trees.
Credit: Will Parson, Chesapeake Bay Program, U.S. Fish and Wildlife Service.
Summary of Primary Actors and Laws Affecting Wetland Migration
Wetlands are regulated under a complex, and often overlapping jurisdictional framework at the federal, state, and local levels. At the federal level, the U.S. Army Corps of Engineers (Corps) is one of the primary agencies that regulate activities in intertidal areas that affect wetlands under two statutes, the Clean Water Act, 33 U.S.C. §§ 1251 et seq. and Rivers and Harbors Act of 1899, 33 U.S.C. §§ 403 et seq.).See footnote 4 States also regulate their coastal zones under the federal Coastal Zone Management Act, 16 U.S.C. §§ 1451 et seq. and may have special protections for wetlands, where certain actions conducted in or adjacent to wetlands may be prohibited or require specific mitigations through permits. Local governments have the primary authority to regulate land uses in their communities through zoning and floodplain ordinances. In particular, zoning ordinances provide the legal framework that governs the use and development of land in a municipality according to different districts based on the uses that are permitted (e.g., residential, commercial, industrial).See footnote 5 Overlay districts can impose additional regulations on an existing zone based on special characteristics in that zone, such as for natural resource conservation.See footnote 6 Before implementing any zoning or land-use changes, however, local governments must ensure that they have the authority to utilize a tool under state law, particularly in Dillon Rule states. In Dillon Rule states, state legislatures must delegate specific powers to local governments whereas, in home rule states, local governments generally have broader authorities.See footnote 7
Governments will have more control to actively manage wetlands and facilitate migration on publicly owned lands. In contrast, where wetlands are being affected by private development, governments will need to consider protections for private property rights. Most land in the U.S. is privately owned.See footnote 8 As wetlands migrate inland, governments will have to consider how development regulations intersect with private property rights.
The greatest concern for most decisionmakers will likely be potential conflicts with the U.S. Constitution’s Fifth Amendment prohibition against the “taking” of private property for public use without “just compensation.”See footnote 9 This protection for private property rights is also included in state constitutions. There are different types of takings that can result. Generally, courts apply a “per se” test to physical occupationsSee footnote 10 and regulations that deprive a private property owner of all or essentially all of his/her property’s economic valueSee footnote 11 but most regulations designed to protect wetlands will be evaluated under a case-by-case-specific balancing test.See footnote 12 Regardless, state and local governments have successfully navigated takings limits and protected sensitive ecosystems analogous to migrating wetlands. While state and local governments must consider constitutional and statutory protections for private property rights, policymakers can likely minimize their legal risk for implementing environmental regulations by being cognizant of existing federal and state takings law (for more information on takings law in a managed retreat context, see the Crosscutting Legal Considerations>Takings section of this toolkit).
As climate change impacts alter both built and natural landscapes, state and local governments should have proactive discussions about the conservation and protection of migrating wetlands. Any actions should be supported by public-private partnerships and communities to balance the tradeoffs and impacts of wetlands on human values and land uses. Policymakers can consider the following practice tips to facilitate wetland migration as a part of comprehensive managed retreat strategies:
- Invest in data: To effectively evaluate and make legal and policy decisions that facilitate wetland migration and conservation, governments must start with data. Successful strategies must be built on and informed by the best available, high-quality data at a local or place-based scale. The potential for wetland migration is highly variable based on different place-based physical factors, such as topography and relative sea-level rise, in addition to information about current and future zoning and land uses and the location of current and proposed structures and infrastructure on or near the coast that can act as barriers to inland wetland migration.See footnote 13 Data and information can come from a variety of sources like the federal and state governments, educational institutions, and nonprofit organizations. For example, some jurisdictions can utilize the U.S. Fish and Wildlife Service’s Sea-Level Rise Affecting Marshes Model (SLAMM), an online modeling tool that allows users to visualize and assess the impacts of sea-level rise on coastal areas under different scenarios out to the year 2100, including predicted impacts to coastal wetlands and shorelines. Nonprofits like the National Audubon Society and The Nature Conservancy have collaborated with various partners to create different mapping layers and sea-level rise vulnerability assessments for coastal habitats, species, and protected lands in different regions on both the East and West coasts of the U.S. Collectively, these types of tools and studies can be used to supplement other local data on zoning, land use, and development to support robust decisionmaking efforts. Still, governments have to account for staff time and training requirements to utilize data and to develop new partnerships for any of these examples.
- Plan for wetland migration: Effective, proactive planning built on data, implemented through land acquisitions and legal tools, and supported by public-private partnerships and community engagement can better ensure that government actions are coordinated, efficient, and maximize benefits for humans and the environment in light of climate change impacts. Governments should consider wetland migration both across different temporal scales and types of plans. First, wetland migration will impact communities differently in the short- (five years or less) and long-term (greater than five years). Governments should incorporate management objectives and priorities for wetlands into both short- and long-term plans to preserve future wetland corridors or establishment areas now before the rate of sea-level rise escalates and potentially hinders migration. Second, a variety of plans at the state and local levels can impact wetland conservation. These include plans for: coastal management; open spaces and parks; natural resources or protected areas; hazard mitigation; floodplain management; zoning and land use (i.e., local comprehensive plans); transportation (e.g., long-range planning); and climate adaptation (e.g., Punta Gorda, Florida).
Decisionmakers can leverage the benefits of wetlands that cut across different sectors and agencies to align planning efforts and coordinate actions that can affect these coastal habitats. For example, federally mandated statewide and metropolitan long-range transportation plans must consider projects and strategies that will “protect and enhance the environment . . . and promote consistency between transportation improvements and State and local planned growth and economic development patterns” and that “improve the resiliency and reliability of the transportation system and reduce or mitigate stormwater impacts of surface transportation.”See footnote 14 Nature-based solutions, such as wetland preservation, can help transportation agencies meet these planning requirements and provide a means of protection for coastal roads with high adaptive capacity and numerous environmental co-benefits.See footnote 15 Governments can also develop wetland-specific management or strategic plans (e.g., Blackwater 2100) that can provide the necessary specificity to evaluate potential management responses on an appropriate place-based scale; these plans can feed into broader state and local plans to account for wetlands adaptation on both site-specific and landscape-scale planes.
- Acquire land to protect and conserve wetland migration corridors and higher ground establishment areas: Land acquisitions can occur through either the purchase of properties in fee simple or development rights (to part of or an entire property) through easements.See footnote 16 Governments can consider different approaches for how to prioritize wetland migration in land acquisitions and maximize the expenditure of limited public funding. Florida and Maryland present examples of state-level legislation and data and tools that account for wetland migration in land acquisition programs, respectively. Governments can also acquire land voluntarily through the in-kind exchange or “swap” of publicly owned land for privately owned land in strategic conservation areas (e.g., Los Cerritos Wetlands, Long Beach, California). Generally, unobstructed land without any structures on it and restricted to human uses compatible with conservation will provide the simplest means and greatest potential for wetland migration. Land in both priority wetland migration corridors and upland establishment areas should be the aim of comprehensive land acquisition strategies for managed retreat. Regardless, land acquisitions present governments with tradeoffs that require substantial investments in funding both in the short-term to purchase land and use rights and the long-term to manage, monitor, and potentially enforce conservation restrictions. Moreover, as land is converted to public ownership, local governments may face revenue decreases due to a loss of private property taxes. Additionally, to voluntarily acquire property, governments must often overcome common barriers to working with landowners, including government distrust and educating residents about the benefits of wetland conservation.
- Develop complementary legal tools: Supplementing acquisitions with regulatory or market-based tools for managed retreat can aid in implementing comprehensive strategies to maximize ecosystem benefits. A non-exhaustive list of legal tools that state and local governments could consider include zoning; setbacks; living shorelines/hard armoring restrictions; and Transfer of Development Rights/Purchase of Development Rights programs. As stated above, state coastal zone management regulations and local government zoning, floodplain, and land-use ordinances will likely be the primary instruments for implementing these tools. Maine’s Sand Dune Rules and a natural resource overlay district from Yankeetown, Florida present two respective examples. Again, governments should implement any actions in partnership with the federal, state, and local actors and per applicable laws and private property considerations to minimize potential legal risk.
- Engage communities and diverse stakeholders: Comprehensive wetland conservation strategies should include community engagement throughout their development and implementation. Wetlands — and the environment and natural resources more broadly—are a part of and not a distinct, isolated element of people’s communities. Wetlands provide several quantitative and qualitative benefits for humans (in addition to other species) including reducing flood damage, improving water quality, supporting fishing, recreation, and tourism economies, and serving as tangible refuse and escape. Residents in local communities should be included in decisions regarding wetland conservation from the outset. Educating residents about the value of wetlands can create local stewards, in addition to enhancing the benefits that can be attained for both people and the coastal environment. Moreover, communities can help state and local governments set management objectives in response to data to determine priority actions, like where to establish wetland migration corridors. As previously stated, not all wetlands can and will be saved, so community input should be sought on these potentially life-impacting decisions.
Of particular note, some property owners in rural areas are concerned that wetland migration or “encroachment” could impact existing and future land uses and development. For example, owners of working lands, like farmers and forest managers, could have their revenue-generating acreage decrease when productive lands are naturally converted into wetlands.See footnote 17 In addition, private property owners facing wetland migration could unknowingly (due to a lack of education and awareness about this phenomenon) become subject to federal and state regulations that protect wetlands and limit development (e.g., Corps Clean Water Act Section 404 permits, state coastal zone management regulations). This can raise questions about how to balance environmental protection and community needs (especially for frontline, underrepresented communities). As sea levels continue to rise, communities and policymakers will have to evaluate how to protect and preserve wetlands and address private property and community concerns. In order to minimize potential conflicts and maximize benefits, governments should engage community members throughout all stages of these decisionmaking processes from planning development to post-implementation monitoring and evaluation. This should include those who own properties, frequently use, or operate businesses in or adjacent to wetlands or areas identified as potential wetland migration corridors.
- Evaluate diverse funding opportunities: Voluntary land acquisitions will necessitate funding, in addition to restoration and conservation activities associated with land management. Governments should seek different types of federal, state, and local funding that can be used for these purposes, and leverage public-private partnerships with conservation nonprofits and land trusts. Governments can also evaluate the potential for generating revenue for holding land in a conservation status, such as a wetland or carbon offset bank (e.g., Los Cerritos Wetlands, Long Beach, California, Greens Bayou Mitigation Bank, Harris County, Texas). This could be supplemented by in-kind exchanges of land (i.e., through a land swap) and other types of in-kind support, like volunteer time for citizen science or restoration activities or the donation of space to hold community meetings. For more information on available funding and financing options, see the Crosscutting Policy Considerations>Funding section of this toolkit.
Managing the Retreat from Rising Seas — Blackwater National Wildlife Refuge, Maryland: Blackwater 2100
Yankeetown, Florida Natural Resource Adaptation Action Area
In 2013, The Conservation Fund, National Audubon Society, and U.S. Fish and Wildlife Service partnered to produce a “salt marsh persistence” report for Blackwater National Wildlife Refuge (NWR) titled Blackwater 2100 to address marsh migration in response to sea-level rise and tidal erosion. Blackwater NWR is a wildlife sanctuary and wetland area of high ecological importance located in Dorchester County, Maryland. The objectives of the report are to identify areas of current tidal marsh most resilient to sea-level rise and of the highest value to salt marsh bird species as well as future locations that may support marsh migration corridors. The report’s authors utilized several tools, including the Sea-Level Rise Affecting Marshes Model (SLAMM), to select one of three different adaptation strategies for wetland areas within Blackwater NWR to create a comprehensive management plan. The three adaptation strategies include: (1) in-place restoration actions targeted at improving existing tidal marsh health and productivity; (2) strategic conservation in priority marsh migration corridors; and (3) actions supporting the transition of uplands into marsh. Blackwater 2100 can provide a useful example for natural resources, open space, and coastal managers to plan for minimizing coastal habitat loss due to sea-level rise by evaluating the tradeoffs of different adaptation strategies; and building partnerships with stakeholder groups and the community to examine marsh migration on an ecosystem scale that necessitates public and private land acquisitions and involvement.
City of Charleston, South Carolina Comprehensive Plan 2021
The Town of Yankeetown, Florida is utilizing a state-authorized land-use planning tool — called Adaptation Action Areas — to mitigate the impacts of sea-level rise on local ecosystems. Specifically, Yankeetown is experiencing coastal inundation due to sea-level rise that is causing large swaths of coastal forests to rapidly decline and salt marshes to migrate inland, creating a phenomenon known as “ghost forests.” Yankeetown has taken a unique approach to planning for coastal change by utilizing Adaptation Action Areas or overlay districts with the goal of increasing resilience to sea-level rise impacts. Yankeetown amended its local comprehensive plan to create a “Natural Resource Adaptation Action Area” (NRAAA). On the town’s zoning maps, NRAAA is composed of two areas — the Resource Protection and Residential Environmentally Sensitive areas — that provide for natural resource protection by requiring no or low-density development (depending on the area) and a 50-foot development setback from water bodies and wetlands. The tool is helping Yankeetown shape future growth and development to conserve and protect its natural resources in the face of rising seas. Local governments could consider adopting overlay districts like Adaptation Action Areas or other zoning, land-use, or planning tools to reduce or limit development in wetland and forest migration pathways as a part of comprehensive retreat strategies.
Managing the Retreat from Rising Seas — Long Beach, California: Los Cerritos Wetlands Restoration and Land Swap
In the Charleston City Plan 2021 (the Plan), the City of Charleston, South Carolina presents a roadmap to guide land-use planning, policy, and investment through 2030 with a focus on creating a more resilient and equitable future, including for wetlands migration. This state-mandated local comprehensive plan can serve as a resource and tool for a variety of users including city staff, residents, and community organizations. One of the Plan's nine organizing elements for Natural Resources outlines the ways that Charleston can design land-use policies to protect natural resources and advance nature-based flood mitigation solutions. The Plan calls for the city to implement land-use and transportation planning strategies to account for marsh and wetlands migration due to sea-level rise, including vegetated buffers to allow space for the wetlands to migrate and restricting development and roadways in tidal flood risk zones. The Plan supports these suggestions and underscores the importance of protecting existing wetlands as well as places expected to become wetlands in the future due to sea-level rise. Wetlands serve as effective nature-based flood solutions. By protecting inland areas and corridors for wetlands to move in response to rising seas, the city can expand its natural flood mitigation infrastructure too.
Land Acquisition and Restoration Projects in the Greens Bayou Watershed in Harris County, Texas: Greens WetBank and Bayou Greenways 2020
The Los Cerritos Wetlands Oil Consolidation and Restoration Project (project) provides an example of how public-private land swap arrangements can be aligned with environmental restoration and protection plans, and used to advance long-term visions for managed retreat. The Los Cerritos Wetlands Complex, located in Long Beach, California, has faced decades of degradation from human activities and development. As a result, the original 2,400 acres of wetlands on the site have been reduced to a few hundred acres of wetlands today. Much of this remaining wetlands area is privately owned and used to conduct oil operations. The proposed project would transfer 154 acres of privately owned wetlands to public ownership as part of a land swap arrangement. Specifically, as a part of the land swap, the 154 acres currently used for oil production will be exchanged for five acres of wetlands currently owned by the Los Cerritos Wetlands Authority. The land swap will facilitate the restoration of a major portion of the wetlands via a mitigation bank, increase public access, and reduce the oil production footprint and consolidate operations. The land swap plan also involves several environmental and social tradeoffs, however. These considerations can provide lessons and recommendations for other local governments studying land swaps as a legal tool to facilitate retreat in coastal areas.
In Texas, Harris County Flood Control District (HCFCD) and other local partners, including the nonprofit Houston Parks Board, are implementing different land acquisition, restoration, and conservation projects in the Greens Bayou watershed in Harris County and the City of Houston. Two programs and initiatives include the Greens Bayou Mitigation Bank (Greens WetBank) and Bayou Greenways 2020. The Greens WetBank is a wetland mitigation bank on nearly 1,000 acres of land in Harris County, where HCFCD restores wetlands and generates revenue by selling “wetland credits” to developers who need to offset wetland losses at locations outside the Greens WetBank’s land in Harris County. The Greens WetBank allows developers to meet federal permitting requirements under the Clean Water Act and dedicate funds to implement projects that improve the environment by restoring wetlands to provide flood mitigation, water quality, and natural resources benefits. In addition, Bayou Greenways 2020 is a large-scale, public-private initiative led by Houston Parks Board to create 150 miles of greenways and trails and an additional 3,000 acres of public greenspace along Houston’s major bayous through land acquisition and conservation efforts. Bayou Greenways 2020 has been the result of an extensive community engagement campaign and funding leveraged from federal, state, local, and private sources to create local parks and open spaces in Houston. Greens WetBank and Bayou Greenways 2020 are examples of how comprehensive land acquisition, restoration, and conservation actions can increase local resilience in a specific watershed by mitigating future flood risks, enhancing the environment, and creating community assets. Other jurisdictions could consider a similar model to coordinate future land uses in a watershed with climate adaptation, including managed retreat strategies, hazard reduction, and natural resource and open space management.
Maryland GreenPrint and Program Open Space
Maine uses different tools through its coastal development laws and regulations — Coastal Sand Dune Rules — to term and condition new development and redevelopment permits to facilitate the protection and inland migration of coastal sand dunes in the face of sea-level rise and shoreline changes. First, the Coastal Sand Dune Rules require that new development approved on frontal dunes be elevated to accommodate shifting sand and water (06-096-355 Me. Code R. § 6(G) (2018)). Second, the rules prohibit not only the new construction of seawalls or similar hard armoring structures that can inhibit inland dune migration, but also any development on property that “may reasonably be expected to be eroded as a result of changes in the shoreline such that the project is likely to be severely damaged after allowing for a two foot rise in sea level over 100 years” (06-096-355 Me. Code R. § 5(C) (2018)). These rules could be analogously applied to coastal wetlands. In addition, the Coastal Sand Dune Rules include explicit protections for coastal wetlands that are a part of coastal sand dune systems (06-096-355 Me. Code R. § 3(H) (2018)). Specifically, if sea-level rise causes a coastal wetland to recede to the point where it extends to any part of an already existing structure for a period of six months or more, that structure must be removed and the site restored to natural conditions within one year (06-096-355 Me. Code R. § 10(A) (2018)). The Coastal Sand Dune Rules provide a useful model for how upland uses can be managed and regulated to minimize impacts to coastal ecosystems like sand dunes and wetlands to enhance their ability to migrate inland without obstructions from development.
Florida Forever Land Acquisition Program
Through GreenPrint and Program Open Space, the State of Maryland has established a set of land conservation and acquisition data tools and programs to protect open space, environmental resources, and rural lands to meet statewide ecological objectives. The tools and programs are used to help the state adapt to climate change by removing barriers to the inland migration of coastal ecosystems in response to impacts like sea-level rise and land loss. Specifically, a statewide mapping tool called Maryland GreenPrint, which displays lands and watersheds of high ecological value, supports prioritized and transparent decisionmaking and increased resilience for vulnerable coastal habitats. GreenPrint allows the state to factor future sea-level rise, habitat projections, and migration corridors into its land purchases through Program Open Space, the state’s open space acquisition program. Together, GreenPrint and Program Open Space provide one example of how a state can incorporate climate change data and tools to facilitate wetland migration into land acquisitions for managed retreat and conservation purposes.
Managing the Retreat from Rising Seas — Punta Gorda, Florida: Climate Adaptation and Comprehensive Plans and Updates
In 1999, the Florida Legislature passed the Florida Forever Act that established the Florida Forever land acquisition and protection program. Florida Forever can serve as an example of how other governments and partners can incorporate climate change and wetland migration into land acquisition programs to enhance adaptation and natural resource conservation. Florida’s state legislature prioritized climate change considerations in the Florida Forever Act (Florida Stat. ch. 259.105(17)(d) (2018)) by requiring the Florida Department of Environmental Protection’s Division of State Lands to evaluate lands for acquisition based on their potential benefits to sequester carbon or adapt to climate change impacts, among other criteria. Since the program's inception, more than 718,000 acres of land have been acquired, including 304,890 of functional wetlands.
Managing the Retreat from Rising Seas — San Diego, California: ReWild Mission Bay
Punta Gorda, Florida incorporated wetland restoration and migration into both its climate adaptation and local comprehensive plans to guide future land-use decisions. The city incorporated its 2009 Climate Adaptation Plan into its comprehensive plan to ensure that climate change is considered in land-use decisionmaking efforts. In 2019, the city released an update to its Adaptation Plan. Among other features, the 2019 update features a more prominent living shorelines component and cites examples of planned relocation or managed retreat implemented between 2009 and 2019 including: increasing sea grass acreage from 247 to 391 acres (a 58 percent increase) and installing living shorelines that, compared to hard armoring structures, can act as a flood buffer and facilitate the inland migration of coastal wetlands; and buying out properties with recurrent storm flood damage and restoring those areas to their natural conditions. The city also recommends potential policy and planning goals in the 2019 update that are compatible with facilitating wetland migration like changing zoning and land-use regulations for sensitive and flood-prone areas by limiting current and future development and prohibiting hard shoreline armoring structures that can act as migration barriers; and conducting coastal realignment planning to address the conversion of land to salt marsh and grassland to provide more sustainable and environmentally friendly coastal defenses.
Sea Level Rise Affecting Marshes Model (SLAMM)
In San Diego, California, the city and various stakeholders are evaluating different land-use and planning alternatives to conserve and restore migrating wetlands in Mission Bay as a part of local decisionmaking processes. To conserve and restore Mission Bay, San Diego Audubon and other partners started an initiative called “ReWild Mission Bay” that evaluated different alternatives for protecting wetlands through a feasibility study. One of the feasibility study’s alternatives aims to relocate Campland on the Bay, an existing RV campground on land owned by the city, inland. By moving Campland on the Bay inland, the city could address wetland migration while providing community resilience and environmental benefits. The alternative to relocating the location for Campland on the Bay, if implemented, would be aligned with and build on other local planning efforts to convert a part of the surrounding Mission Bay Park into a regional amenity that accommodates both public and private uses. In July 2019, the San Diego City Council approved a lease extension and expansion for Campland on the Bay that has delayed any potential implementation of the ReWild Mission Bay wetland alternatives until after the term of the lease expires. The ongoing work in Mission Bay can serve as an example for other coastal jurisdictions addressing the tradeoffs raised in land-use and planning efforts for coastal retreat and the challenges that can arise in balancing competing stakeholder interests to achieve both human and environmental priorities.
Conserving California’s Coastal Habitats - A Legacy and a Future with Sea Level Rise
The Sea-Level Rise Affecting Marshes Model (SLAMM), from the U.S. Fish and Wildlife Service, is an online modeling tool designed to present sea-level rise scenarios to the public. It can be used to inform adaptation efforts including restoration of marshes, strategic land acquisitions, and infrastructure management.
The Nature Conservancy Resilient Coastal Sites for Conservation in the Northeast and Mid-Atlantic
The Nature Conservancy in California and the California State Coastal Conservancy collaborated on this sea-level rise vulnerability assessment of California’s coastal habitats, imperiled species, and conservation lands. This study is the first of its kind to assess the sea-level rise vulnerability of all coastal habitats along the entire coast of California, including the San Francisco Bay and Delta. Vulnerability results were used to develop key strategies to protect coastal habitats and at-risk species from sea-level rise and other stressors, as well as determine new priority areas to preserve these habitats. The study and the strategic priorities offer valuable guidance for regional planners, agencies, land managers, conservationists, and other stakeholders working for the future of coastal resilience in California.
Massachusetts Audubon Mapping and Prioritizing Parcels for Resilience Tool
In 2017, The Nature Conservancy (TNC) released a report and interactive web map that identify priority sites in the northeast and Mid-Atlantic regions that have the ability to maximize both biodiversity and natural services in response to increasing threats from rising seas. TNC — in partnership with a variety of stakeholders and scientists from other nonprofit organizations, universities, and state and federal agencies — conducted a two-year study to evaluate more than 10,000 individual sites throughout the region. TNC assigned each site a “resilience score” based on the capacity for a site’s coastal habitats to migrate to adjacent lowlands. This data can help state and local decisionmakers identify and prioritize coastal habitats for long-term restoration, conservation, and preservation purposes through tools such as land acquisitions and conservation easements, and zoning and land-use policies.
In 2016, Massachusetts Audubon Society joined The Nature Conservancy and LandVest to create the Mapping and Prioritizing Parcels for Resilience (MAPPR) Tool. The MAPPR Tool can help state and local governments, communities, and land trusts define planning priorities and identify conservation opportunities, including to facilitate wetland migration. The MAPPR Tool includes four mapping layers that can help policymakers and conservationists select specific geographic areas (e.g., town, county, watershed) within the state and identify parcels of land like wetlands migration corridors and higher ground establishment areas that, if protected, would maximize environmental and community benefits.