Wetland restoration means returning natural functions to a wetland that was drained, filled or degraded. That means rebuilding its hydrology, soils and native plant community so it works like a wetland again. On the Gulf Coast it covers everything from removing fill from a tidal creek in Biloxi to rebuilding marsh with dredged material and controlling invasive species in coastal preserves.
Restoration, enhancement, creation and preservation
These terms are different but related. Federal mitigation rules (33 CFR 332.2) define them precisely, and the differences matter when a project counts as mitigation.
- Restoration returns natural or historic functions to a former or degraded wetland. It has two parts. Re-establishment rebuilds a former wetland and gains both area and function, for example removing fill that was placed on a historic marsh. Rehabilitation repairs functions in a degraded wetland that still exists. It gains function but not area.
- Enhancement improves specific functions of an existing wetland, such as removing invasive species. It doesn’t add area, and it can trade one function for another.
- Establishment (creation) builds a wetland on an upland site where one didn’t exist before.
- Preservation protects an existing wetland from a threat, usually with a conservation easement. It doesn’t add area or function.
What a restored wetland needs
Planting alone doesn’t make a wetland. Successful projects get these right:
- Hydrology first. The site needs the right water budget: how often it floods, for how long and how deep. On tidal sites, finished grades must sit within the elevation range the target marsh can tolerate. Inland, it can mean filling drainage ditches or plugging old drains.
- Grades and soils. Removing fill, reshaping banks and restoring the natural floodplain surface are often the main earthwork. Sometimes new marsh-suitable soil has to be placed.
- Reference sites. Nearby healthy wetlands of the same type set the target species list, planting densities and elevations.
- Native plants and invasive control. Plant palettes are matched to salinity and soils. Invasive species are controlled before and after planting.
- Erosion control during construction. Bioengineered materials such as erosion matting protect water quality and new plantings.
- Monitoring and adaptive management. As-built and annual monitoring show whether the site is meeting its goals, and adjustments are made if it isn’t.
Gulf Coast challenges
Restoring wetlands on the coasts of Mississippi, Alabama, Florida and Louisiana comes with problems inland projects don’t face. Salinity sets which plants survive. Subsidence and sea level rise change the elevation targets over time. Storm surge can reshape a site overnight. And invasive plants can overtake a site quickly if they aren’t controlled. Urban sites add stormwater, sediment and trash from the surrounding watershed, so restoration has to account for what flows in, not just what’s on site.
Case study: Bayou Auguste, Biloxi, MS
Bayou Auguste is a tidal creek in east Biloxi that drains about 390 acres of urban downtown and neighborhoods into Back Bay of Biloxi. Over decades it had been channelized and hemmed in by fill and development. Working with the Land Trust for the Mississippi Coastal Plain and the Gulf Coast Community Design Studio, Cypress provided ecosystem restoration design, environmental engineering and construction oversight across four phases from 2010 to 2015:
- Phases 1 and 2 restored about 754 feet of bayou shoreline and 0.45 acres of tidal marsh by removing fill and a concrete retaining wall and restoring native marsh grades. The work earned a Citation Award from the Mississippi Chapter of the American Institute of Architects.
- Phase 3 removed construction debris, riprap, soils and dumped refuse near the bayou mouth, placed marsh-suitable soil in the subsided floodplain and stabilized it with bioengineered erosion matting.
- Phase 4 restored the floodplain and reshaped the banks between Davis Street and Braun Street, with native upland plantings on the park side. The program received a first-place USEPA Gulf Guardian Award (Civic Project) in 2015.
Each phase used local reference habitats to set species lists and densities, a pre-project baseline assessment, a bioengineered SWPPP and follow-up monitoring.
After 2015, utility work in the watershed sent sediment into the bayou and altered the restored floodplain. In 2018 the Land Trust hired Cypress for a restoration plan with construction plans, specifications and a hydraulic model. A HEC-RAS model of ten design storms showed that the repairs would not increase flooding in the watershed. Restoration isn’t a one-time event. Urban wetlands need a plan for the watershed around them. More on the Bayou Auguste floodplain restoration.
Coastal preserves: protecting marsh that’s already there
Not every project starts with a bulldozer. In the Hancock County marshes, Cypress has mapped invasive species on the Wachovia tract for the Mississippi Department of Marine Resources’ Coastal Preserves program. Knowing where invasive plants are spreading lets the preserve target control work before native marsh is lost. That’s enhancement and preservation working alongside restoration.
Restoration as mitigation
When a 404 permit requires compensatory mitigation, restoration is often the preferred way to provide it, through a mitigation bank, an in-lieu fee program or a permittee-responsible site. Mitigation restoration carries more paperwork: performance standards, long-term monitoring and financial assurances. See what wetland mitigation is and living shorelines for Gulf cities.
How Cypress helps
Cypress Environment & Infrastructure provides wetland restoration services from feasibility through monitoring: site assessment, wetland delineation, hydraulic modeling, restoration design, permitting, construction oversight and monitoring across Mississippi, Alabama, Florida and Louisiana. We’ll also tell you when a site isn’t a good restoration candidate. Contact Cypress to talk through your site.
Frequently asked questions
What is wetland restoration?
Returning natural functions to a wetland that was drained, filled or degraded by rebuilding its hydrology, soils and native vegetation.
What is the difference between wetland restoration and enhancement?
Restoration returns functions to a former or degraded wetland and can add wetland area. Enhancement improves specific functions of an existing wetland without adding area.
What are common wetland restoration techniques?
Restoring hydrology, removing fill, regrading to target elevations, placing suitable soils, planting native species from reference sites, controlling invasive species, and monitoring.
How long does wetland restoration take?
Construction can take weeks to months, but plants establishing and monitoring usually take several years. Mitigation sites have a set monitoring period.
Can wetland restoration count as mitigation?
Yes. Restoration is a common form of compensatory mitigation for 404 permits, through mitigation banks, in-lieu fee programs or permittee-responsible projects.