Return to Newsletter >>

Salt Marsh Restoration Best Practices
The restoration of salt marshes and tidal wetlands has become increasingly more active over the past decade.  The importance of tidal wetlands extends far beyond the geographical boundaries of the wetland.  For instance, tidal wetlands provide habitat for a wide variety of floral and faunal species, Aerial photo of restored salt marsh a nursery for many wildlife species, and a food source that forms the first link in a complex food chain.  If the foundation of the food chain is removed, then a range of fish species will suffer, from creek minnows through saltwater commercial and sport fish.

Wetlands also naturally absorb nutrients and pollutants, and help improve overall water quality.  Waterfowl nest and forage in wetlands, and diverse ecosystems from shellfish through mammals find refuge in wetland environments.

As the tragedy of Hurricane Katrina demonstrated, the erosion of our national wetland environment also exacerbates flooding and damage to infrastructure.  The loss of nearly a football field sized wetland every half hour in Louisiana not only results in loss of valuable habitat and fisheries commerce, but it also reduces the desperately needed natural flood protection buffer.

Restoration of wetlands is important to the scientific community and to the public as well.

So, how can salt marshes and tidal wetlands be restored?  The following steps should be followed when completing a wetlands restoration project:

  • Identify project site(s) and stakeholders
  • Select project goals and restoration objectives
  • Define project success criteria
  • Complete a feasibility study
  • Complete an engineering design using the Ecological Engineering process 
  • Obtain applicable permits
  • Public outreach
  • Complete the construction
  • Conduct post construction monitoring using the Adaptive Management process

While these steps may seem daunting, the complexity depends on the scale of the project.  A small-scale restoration project that will enhance a relatively small section of marsh may combine several steps; however, a successful large-scale project will most likely require all the steps defined above.  A few key steps are discussed below, centered on a representative large-scale wetlands restoration project.   

Establishing project goals and restoration objectives is crucial.  The goals should be simple and straightforward.  The most common mistake in restoration projects is setting extremely complex or Before restorationunreasonable goals and objectives.  Designs also can vary widely if the goal is to restore vegetation, fisheries habitat, avian forging area, and/or floor protection capacity.  For instance, tide gates may be used to encourage ponding for waterfowl habitat restoration; however, the same tide gate may retain freshwater and create conditions not optimized for restoration of desirable species such as Spartina alterniflora.

Another key step in the restoration process is to define a criterion by which project success can be judged.  Success criteria should be composed of quantifiable parameters and not vague statements or concepts.  An example of a good success criterion would be “The restoration project will restore the site hydrology so that it will support colonization by Spartina alterniflora, and reduce Phragmites coverage to less than 10% of the site acreage.”  This statement is measurable and can be quantified.

Completing a feasibility study is an important step in the planning phase of the project because it helps ensure the project can be completed and/or helps develop the initial project cost estimates.  The scope of the feasibility study should be scaled appropriately for the size and complexity of the restoration project.  Often, feasibility studies in tidal systems include a hydrodynamic numerical model to determine/quantify the desired tidal hydraulics within the site that will support desirable marsh plain vegetation.  Additionally, the feasibility study should include a site inventory of vegetation, identify stakeholders, confirm availability of the site, and define conceptual design alternatives.

Developing the engineering design should involve the application of Ecological Engineering.  Ecological Engineering is a straightforward concept that says nature is a better designer of restoration projects than engineers, regulators, or ecologists.  Ecological Engineering emphasizes natural self-design over complex engineering and extensive construction.  In a wetlands restoration project, it is usually not possible to know all the details required to complete a detailed engineering design that will result in a fully function wetland immediately after construction.  Therefore, the application of Construction PhaseEcological Engineering calls for an appropriate level of design to allow nature to complete the initial restoration design process.  An example of this is the excavation of marsh channels.  An application of Ecological Engineering would call for the design and construction of a primary and secondary channel system, while allowing the tertiary and smaller channels to evolve naturally where and to the size, elevation, and slope that the marsh plain dictates.  The advantage of applying Ecological Engineering is that the resulting design is better suited for restoring the ecology of the wetland system, and it usually costs less because less construction is required.

The modification of a wetland often involves changing the landscape.  Change is often viewed with skepticism and/or uneasiness by the regulatory community and the stakeholders.  Therefore, an effective public outreach program is essential for restoration projects.  This allows the project proponent to reach out to the stakeholders and cooperatively define the scope of a restoration project.  Public or local neighborhood meetings can often speed the project along by gaining support for the project. Involving the public in the design process also can ensure the project meets the community expectations.

Adaptive Management is a monitoring process that evaluates the progress of the restoration against the goals and objectives set forth in the earlier steps.  Monitoring data are evaluated by the Adaptive Management Team to determine if it is necessary to intervene in the restoration project.  Sometimes a project will require a nudge to return it to its restoration pathway.  This nudge may involve more aggressive invasive species eradication, or slight modifications to topography or After restorationhydraulic designs.  When possible, such flexibility should be included in the design and permitting processes as part of an adaptive management provision. 

Restoring wetlands is an extremely valuable endeavor that helps not only the ecosystem but often the overall economy.  Even restoring a small wetland of less than an acre can be significant when considered in a landscape perspective.  If 10 or 20 small wetlands restoration projects are completed within the same watershed, the combination of those projects may have a significant beneficial impact on the watershed.

 

 

Lee Weishar, Ph.D., PWS

Lee Weishar, Ph.D., Senior Coastal Engineer/Professional Wetland Scientist
Dr. Weishar has over 20 years of experience in coastal engineering and wetland/marsh restoration.  Dr. Weishar specializes in the integration of biological, ecological, and hydraulic data to develop wetland restoration designs and to ensure that the design will meet the restoration objectives.  Additionally, Dr. Weishar specializes in evaluating the potential impacts of proposed restoration projects on existing wetlands and adjacent transitional, buffer, and upland areas.

Return to Newsletter >>

Woods Hole Group

 

 

 

Woods Hole Group