Coastal wetlands provide a vast array of benefits. They shelter numerous animals (especially fish and birds), thus helping to maintain biodiversity. Wetlands are a source of carbon-based particles and dissolved materials that enter adjacent waterways and support production of fishery species. They also moderate storm/flood damage to upland areas by slowing advancing water. All these functions are dependent on the flow of water that links the wetlands to adjacent estuaries. The value of functional wetlands as identified by various researchers was the justification for including coastal wetland restoration as a high priority in the Indian River Lagoon Surface Water Improvement and Management Plan, the Indian River Lagoon Surface Water Improvement and Management Plan 2002 Update, the Comprehensive Conservation and Management Plan for the Indian River Lagoon National Estuary Program, the Northern Coastal Basins Surface Water Improvement and Management Plan, and the Mosquito Lagoon and Tomoka Marshes Aquatic Preserve Management Plans.
Many coastal wetlands have been crisscrossed with hundreds of miles of mosquito control ditches. The most damaging of these ditching efforts used large excavation equipment, called draglines, to ditch through wetlands; most of it during the 1960s. A large concentration of these ditched wetlands are found in northern and central Mosquito Lagoon (approximately 1,200 acres), with others located throughout coastal Florida. Restoration of these impacted wetlands was initiated in 1999 through a pilot project in coordination with the Volusia County Mosquito Control (VCMC) and Canaveral National Seashore (CNS). Over 50 acres of wetlands were restored under the pilot project by contracting the use of an amphibious excavator to regrade spoil piles into the ditches. Over 625 acres of dragline-impacted wetlands have been restored in Volusia County with support of the St. Johns River Water Management District (SJRWMD).
The SJRWMD and its partners have been very successful at securing funding for this work. The largest amount of support has come from the US Fish and Wildlife Service’s National Coastal Wetland Conservation Grants Program (USFWS). This program has provided over $1 million to fund 2 phases of restoration. Phase 1 funded restoration of 286 acres of dragline-impacted wetland. Phase 2 was interrupted by loss of access to a specialized piece of equipment. Restarting the project required finding new equipment and a new site.
Acquiring equipment and a suitable site
All disturbed coastal wetlands between Jacksonville and Ponce de Leon Inlet were mapped prior to 2007, and staff used these maps to identify a suitable, publicly owned site to support a request for an extension of a grant from the USFWS that was submitted in mid-2017. The site in southern Flagler County was identified as a possible candidate by the St. Johns River Water Management District (SJRWMD) because it met key criteria, including it was degraded due to ditching in the 1960s and 1970s, it was undergoing further degradation as the remaining patches of wetland convert to less productive open water, it was on publicly owned land, and it was just north of an area where previous restoration had been successful.
The concept received support from staff of the Florida Department of Environmental Protection’s (FDEP) Park and Aquatic Preserve and the Florida Fish and Wildlife Conservation Commission (FWC). In response to a coordinated request from this partnership, the USFWS approved an extension of its grant in November 2017. By February 2018, we had notified staff at Flagler County and East Flagler Mosquito Control District.
SJRWMD reviewed the damage to wetlands from the extensive ditching efforts in the 1960s and 1970s. There was little of intact habitat remaining with the boundaries of the proposed project. The area is dominated by ditches and piles of spoil. In fact, more than 61,000 feet or more than 11 miles of ditch exist within the targeted area.
SJRWMD continued with a thorough review of the history of the site by seeking the locations of historical and cultural resources. The Florida Park Service (FDEP Division of Recreation and Parks, District #3) had some preliminary information on cultural resources in the project area. All known locations were excluded from the project. These locations included a 1951 intracoastal waterway right of way marker, an area of eroding natural upland along the intracoastal waterway with exposed pottery shards, and a road that had connected the Smith’s Creek (Bulow House) House of Refugee on the beach to the upland. The Park Service also has provided all this information to the Division of Historical Resources for their review. We received the results of that review in a letter dated Aug. 15, 2018 (DHR Project File No.: 2018-3603). The Park will provide trained staff to monitor these cultural resources.
Given positive results from these reviews, they were followed by a review of logistics that examined suitable locations for staging equipment, access to the site, and the influence of tides. Once this background was assembled and vetted by the partners, SJRWMD used it to prepare applications for permits to restore 113 acres. The applications were submitted to FDEP and the U.S. Army Corps of Engineers (USACE) in July 2018. The FDEP permit was received on Aug. 7, 2018. The USACE issued their permit on Aug. 23, 2018.
Oyster reefs were mapped from aerial photography taken in 2015, and they will be avoided during restoration. During the project, on-site reconnaissance by an experienced ecologist will identify additional reefs, remnant wetlands, natural uplands, and other areas to be avoided. In addition, any accidental damage will be reported to the relevant authorities, and a remediation plan will be created, implemented and monitored for success. Such an approach was employed in response to the single accident that has occurred in 18 years of restoration: an operator tracked across one oyster reef. The situation was brought to the attention of regulators, remediation was planned and implemented, and the site was monitored until it recovered fully, which was within six months. Shellfish harvesting will not be affected by the project because it is prohibited year-round in these “unclassified waters.”
The project plan includes the same techniques used for dragline ditch restoration projects since inception (see Construction Methods). This work will benefit from the experience gained on the numerous projects since the original pilot project in Volusia County. The plan has been developed in consultation with FDEP Aquatic Preserve and State Park staff. All work occurs within the historical footprint of previously-disturbed coastal wetlands and on state-owned lands. No natural upland will be disturbed, and no excavation below existing wetland elevation will occur.
Dragline ditch restoration will be accomplished using the following procedure. Work areas will be isolated by the installation of turbidity screens at the estuary interface of all tidal creeks and ditches. Standard turbidity controls have been effective at all sites where restoration work has occurred. Turbidity screens will remain in place for approximately two months after restoration to allow all surfaces to stabilize. Our experience and in situ monitoring (e.g., water quality) indicate that two months post construction is more than adequate for this purpose. Vegetation on the spoil piles will be cleared and placed in the portions of the ditch to be filled using an amphibious excavator. Spoil will be returned to the borrow ditch covering the vegetation. No material will be excavated below existing marsh elevations.
Target elevation will be determined on site from biological indicators in adjacent intact wetlands. The excavator will work primarily from the existing ditches, moving backwards and filling the ditch behind it. Due to soil oxidation and compaction, the excavator may not completely fill all ditches to marsh elevation. If necessary, some ditches will be narrowed but left connected to the estuary to reduce the potential for a mosquito breeding problem. By leaving ditches narrowed or unfilled, restored areas can be brought up to existing marsh elevation reducing the need for future mosquito treatment. All surfaces will be leveled to existing adjacent wetland elevations (no slope) just inches above mean water level. No new excavation below existing marsh elevation will occur. No natural upland will be excavated.
The restoration contractor is limited to working between 7 a.m. and 6 p.m., with no work occurring on holidays or weekends. Exceptions to these limits must be approved by the SJRWMD. SJRWMD staff and third-party observers familiar with this type of work will manage the work alongside the contractor. If damage occurs, we will address it on a case by case basis.
Following our extensive and successful experience with this method, the restored surface will be allowed to revegetate through natural recruitment or vegetative growth/expansion from adjacent wetland plants. As an example, similar sites at the Merritt Island National Wildlife Refuge had 10 to 30 percent cover by six months and 50 to 80 percent cover by 18 months (Donnelly 2014 Ph.D. Dissertation, University of Central Florida). Response may vary due to weather, availability of plants to recruit to the area and other factors not related to the restoration process.
UPDATE: The District has approved the contractor’s request to use a second excavator. The new excavator will be brought into the project area on or after June 13, 2019. The second excavator will help to expedite completion of the project and finishing more segments during the growing season should also help the restored wetlands revegetate sooner. The second excavator is an amphibious Caterpillar 312D, which is slightly smaller than the Caterpillar 320D already in use.
Coastal wetlands provide many benefits, including production of food that supports fish, birds and other wildlife; provision of a refuge where small fish can find escape from predators; protection from storms by dampening the energy of waves and storm surge; filtering and cleaning of water; and a habitat that is resistant to invasion by exotic plants. For example, Barbier and co-authors (Ecological Monographs, 2011, 81(2): 169–193) document benefits from multiple studies of coastal wetlands. Benefits from a single acre of coastal wetland are estimated at over $2,000 per year for protection from storms, over $700 per year for water purification, and over $6,000 per year for support of fisheries on Florida’s east coast.
Despite these benefits, coastal wetlands have been filled or damaged throughout the world, and the area targeted by this project has been damaged by two rounds of ditching that converted viable wetland into piles of spoil and over 11 miles of ditches filled with water. These alterations were designed to reduce breeding by the saltmarsh mosquito, and they worked. Unfortunately, the alteration led to multiple unintended consequences. The ditches were deep enough to allow predatory fish to enter what had been a nursery or refuge for small, juvenile fish. The piles of spoil were colonized by upland plants and invasive, exotic plants, like Brazilian pepper. Less wetland meant less filtering and cleaning of water, which is detrimental to a waterbody that is not attaining standards due to the presence of excess nutrients. The loss of wetlands also reduced the amount of food produced for fish, birds and other wildlife; and the few remnants of untouched wetlands were made vulnerable. These smaller patches of wetland cannot retain enough sediment to keep pace with rising sea levels, so they convert to open water as shown by an analysis of aerial imagery spanning 1943–2014. Thus, the “do nothing” option leads to further loss of the benefits generated by the area. The planned restoration is designed to prevent this degradation and address the other undesirable consequences of ditching.
In a nutshell, the restoration consists of moving the piles of spoil back into the ditches and grading the material to the elevation that matches nearby remnants of natural wetland. Similar work has been completed during the past 18 years, with about 250 acres returned to wetland elevation. On average, about 40 percent of the acreage in a ditched area can be returned to wetland because the spoil that remains after decades of exposure is insufficient to fill the ditches. In the case of this project, about 40 acres is expected to be returned to functional wetland that will provide food for fish and wildlife, buffering against storm surge, filtering and cleaning of water, and other benefits that sum to over $8,000 per acre per year.
Areas graded to the right elevation are revegetated through natural recruitment, and the restored wetlands attract a natural assemblage of animals. Recovery of vegetation in similar projects along the Indian River Lagoon is depicted in the graph below, with Zone 4 (interior marsh) representing remnant wetland that was not altered (Donnelly, 2014, Ph.D. Dissertation, University of Central Florida). In addition, surveys of birds at restoration sites in the North Peninsula State Park and along the Indian River Lagoon document extensive use of the restored areas by shorebirds and wading birds. Larger fish may be excluded from the shallower ditches after restoration, which may make them harder to catch, but multiple studies show that wetlands support such fish (Barbier and co-authors, Ecological Monographs, 2011, 81(2): 169–193). All information regarding the restoration process and its results comes from evaluations of sites restored with similar methods. Key findings have been reported in peer-reviewed journals, technical reports to managers, numerous presentations at scientific conferences, and theses or dissertations. For example, a description of past work can be found in a peer-reviewed journal article published by Rey and coauthors (Wetland Ecology and Management, 2012, 20: 197–211).
In addition to restored wetland, the project provides an ancillary benefit by eliminating piles of spoil that support exotic, invasive species like Brazilian peppers. These invasive plants are buried in the ditches to expand the amount of restored wetland. The buried plants do not regrow, and new plants do not appear once the habitat they need is gone.
Over the years, partnerships undertaking restoration of degraded wetlands have worked near numerous communities, with one area being less than a mile south of this proposed site. Successful projects also have been completed near Oak Hill, Bethune Beach, Edgewater, and Ormond Beach. Like this proposed site, each had a mix of intact and impacted areas. Previous restoration has not adversely affected adjacent areas. The restored wetland surface will be inundated by natural tides more frequently than the current spoil areas, but upland flooding is not expected to change as a result of the project. In fact, wetlands provide protection against waves generated by storms because they cause the wave energy to dissipate slowly rather than rebound off a hard surface, and the ability of wetlands to maintain their viability by accumulating sediment means that they are one of the best habitats for providing ongoing benefits in the face of rising sea levels.
Land adjacent to homes will not be altered and tides will not be restricted or magnified so saltwater intrusion, wells and septic systems should not be affected. Furthermore, mosquito breeding will not be increased because ditches that cannot be filled will be narrowed and left connected to the estuary. Partnerships with Volusia County Mosquito Control have shown that this reduces the potential for a mosquito breeding problem. In addition, similar projects have been successfully completed in State Parks, Aquatic Preserves, the Canaveral National Seashore and National Wildlife Refuges. Managers of these areas would not endorse, participate in, and co-fund these projects if there were serious concerns about adverse impacts or serious doubts about the ultimate benefits.