Thoughts on Wetland Restoration
Throughout the world, as wetlands are being recognized for their important contributions to ecosystem health and human welfare, they are at the same time being filled, dredged and otherwise impacted by a growing population. It has been well documented that wetlands play a vital role in water quality protection, flood control, and habitat for fish and other wildlife. However, over the past 200 years we have witnessed the loss of over half of the original wetlands in the continental U.S. Wetland conservation should be, and typically is being employed as the first step in preventing future losses to both tidal and non-tidal wetlands. While wetland conservation will help stem the tide of wetland losses, it will however not be enough to bring back the lost ecosystem functions that wetlands provide. What is needed is a concerted effort to restore wetlands throughout the world. The Ramsar Convention on Wetlands, (http://www.ramsar.org ) an international intergovernmental treaty on wetland conservation, recognizes the importance of wetland restoration as a major component of achieving sustainable development throughout the world.
Examples of wetland restoration throughout the globe are many, including recent efforts to restore the Mesopotamian Marshlands (http://www.iraqfoundation.org/projects/edenagain/) in Iraq; the mighty Logone Floodplain in Cameroon; the tiny Hestur Mire in Iceland; Azraq Oasis in Jordan; Hula Lake in Israel; Lake Karla in Greece; Babina and Cernovca Polders in the Danube Delta of Romania; River Skjern Delta in Denmark; shoreline marsh restoration areas in Maryland;Everglades Swamps in Florida; and mangrove restoration in Thailand, the Philippines and Indonesia.
Restoring a wetland to a self sustaining naturally functioning condition is a complex process that requires expertise, resources, and commitment from many different stakeholders. Ideally, a successfully restored wetland will mimic the functions of a healthy natural wetland. All restoration projects (see the SER Primer on Ecological Restoration – www.ser.org) require planning, implementation, monitoring, and management. Many projects require a team with expertise in ecology, hydrology, engineering, and environmental planning. We are fortunate to have spent some time with one of the true pioneers in wetland restoration and an expert on the tidal wetlands of the Chesapeake Bay region, Dr. Edgar Garbisch. See his interview below. This issue of Leaf Litter contains a variety of information and links to wetland restoration throughout the world. Go ahead, jump right in and get your feet wet and hands muddy, and restore a wetland while you are at it!
Leaf Litter Talks with Edgar Garbisch
If you know anything about wetland restoration you’ve probably heard of Dr. Edgar Garbisch and the ground-breaking work he has undertaken in tidal wetland restoration. In 1972, long before most of us even thought of ecological restoration, Ed founded Environmental Concern, a public non profit corporation dedicated to wetland education, restoration and research (www.wetland.org). Dr. Garbisch, then President and director of EC, pioneered the technology needed to construct tidal marshes, taking the method from experimental stage to proven success in the field. Since then Environmental Concern has taken their success and lessons learned to design and construct over 700 non-tidal and tidal wetlands throughout the eastern U.S. We thought you might like to know more about Ed, the work he’s done and tap into what he has learned over the course of his career in restoring wetlands.
Tell us a bit about your background on your pioneering work in wetland restoration.
My work in wetlands began in 1971 when I, along with colleagues Dr. Paul Woller and Dr. Robert McCallum, embarked on a wetland restoration project to restore a section of Hambleton Island (Maryland’s Eastern Shore), which had eroded into two islands, back to a single section through the creation of over two acres of tidal brackish marsh.
The project, which required our team to propagate nearly half a million wetland plants and 6 different species, led to the founding of Environmental Concern, Inc. in 1972 as a public not-for-profit company and the first wholesale wetland nursery in the USA. Over the past 30+ years, Environmental Concern has constructed (created, restored or enhanced) over 700 non-tidal and tidal wetlands throughout the eastern United States.
You publish a “Dos and Don’ts of Wetland Construction”. What are your top dos and don’ts?
In non-tidal wetlands the top priority is to understand their hydrologies. Whether you’re dealing with a ground water supported or surface water supported wetland or combined – there are critical hydrologic calculations that will enable you to design a plan that will be supported by the hydrology in that area and which greatly increases the chances of a successful wetland. The hydrology is also so dependent on the meteorological conditions – weather. Even if weather conditions are “average” you still face the problem of achieving the right volume of water to sustain the wetland.
In tidal wetlands the hydrology is much simpler — unless you have a restricted situation such as bringing a tidal wetland pond into your property where you have to pipe the water in or channel it in from a tidal water body. In that situation, you have the potential problem of restricting the water so that the conveyance structure – the pipe or the channel – isn’t large enough to convey the total volume of water that you need for the size of the wetland you’re constructing. Then you have a hydrological problem where the tidal range inside the wetland is not going to be the same as that outside the wetland.
Other than that, the ocean provides an infinite body of water so you’re not worried about volume of water in tidal wetland as you are in non-tidal. The volume of water is critical in non-tidal wetlands. You have to have enough volume of water to fill the wetland to your pool level and maintain it. So a tidal wetland system is really a much simpler wetland system to design and construct.
In tidal wetlands you need to be concerned about the plant communities that you’ve assigned to the various elevations in the tidal range. The main concerns are things such as stability of the wetland, animal feeding, exposure, climate, and having the right plant communities for the different elevations of the wetland.
How can our readers obtain a copy of this publication?
Visit our web site: www.wetlands.org and click on “publications”.
What are some common mistakes restoration practitioners can avoid in wetland restoration?
In non-tidal wetlands most mistakes are hydrological in nature. Wetlands are often not properly designed in size and overall design for the hydrology that is available for that wetland. Practitioners either don’t know how to do the proper hydrologic calculations or they don’t even bother doing them. They simply dig a hole in the ground and hope there is going to be sufficient run-off, ground water, or direct precipitation to support that wetland. And weather conditions are changing throughout the world and this complicates the hydrology issue, since average conditions over the years no longer apply.
Do you see the potential for sea level rise as a major challenge to tidal wetland restoration? What measures can we take to mitigate this concern?
Yes – it is one of the reasons why many wetlands in the southeast are drowning. The rise of the wetlands due to peat buildup and sediment trapping can’t keep up with the rate of sea level rise and land subsidence. In the Chesapeake Bay we are dealing with both sea level rise and land subsidence – the dropping of land which leads to the effective sea level rise. Tom Horton does an excellent job of explaining this in his book “The Turning of the Tide”.
It’s amazing, however, what we’re seeing on properties on which we’ve done work. Luckily, on all the wetlands we’ve constructed, the biological composition of the wetlands has not changed in 30 years. The ground has actually risen due to below ground biomass accumulation which leads to the formation of peat and the peat builds up and you get peat banks along the edges of the wetlands. These wetlands have essentially risen at the same rate as the sea level has risen and the land has subsided. We’re very lucky that this balance exists in our area of the Chesapeake Bay and enables our wetlands to be sustained.
In many other areas along the south Atlantic coast, lands are subsiding and sea level is rising such that lands are just being flooded and disappearing. These conditions are probably the biggest challenge in sustaining constructed tidal wetlands.
What measures can we take to mitigate this problem… there’s not much we can do to offset this natural occurrence. In some areas there is talk of dredging channels and filling these once-wetlands with soil to bring them up to elevation so they will support plants again.
What do you believe is the best procurement method for wetland restoration: design-bid-build or design-build?
Design-Build. The best case scenario and the best quality work is done when the firm bidding the job do both the design and construction. You will have the highest quality work and best coordination of the work when you have a firm that can do both – like Biohabitats – doing the work. It also allows for the best coordination of construction because seasonal timing is often a critical factor. A design and construction firm is more aware of the complicating factors and you have a much better chance of success.
Do you see an advantage to wetland mitigation banks?
The only problem I see with mitigation banking is that a qualified wetland may not necessarily be mitigating for the same type of wetland that is being destroyed – it’s not an equivalent exchange. For example, there may be a mitigation bank that is a non-tidal ground water supported wetland but you may loose a wetland that is surface water supported.
Other than that, banking is very good even if you’re not mitigating the exact type of wetland that is being destroyed. In order for the wetland mitigation bank to be approved it has to be successful so you know you’re buying into a successful effort.
Anything else you’d like to add?
Wetland construction (restoration, creation, and enhancement) is a multidisciplinary science – it’s quite different from other types of restoration like prairie restoration and other types of habitats because the hydrological component is very complex. The key to a successful wetland lies in the right mix of the hydrology and the plant communities.
Society of Wetland Scientists http://www.sws.org/
Association of State Wetland Managers http://www.aswm.org/
Environmental Laboratory Wetlands http://www.wes.army.mil/el/wetlands/wetlands.html
Handbook for Wetlands Conservation & Sustainability: a guide for planning and implementing a community wetlands projects http://www.iwla.org/sos/handbook/
EPA Wetlands homepage http://www.epa.gov/OWOW/wetlands/index.html
An Introduction and User’s Guide to Wetland Restoration, Creation, and Enhancement http://www.epa.gov/owow/wetlands/pdf/restdocfinal.pdf
U.S. Fish and Wildlife Service National Wetlands Inventory http://wetlands.fws.gov/
Classification of Wetlands and Deepwater Habitats of the United States http://www.npwrc.usgs.gov/resource/1998/classwet/classwet.htm
Society for Ecological Restoration International http://www.ser.org
Estuarine Research Federation http://erf.org
Environmental Concern http://wetland.org
Wetlands International http://www.wetlands.org
Restoration of Tidal Wetlands from Phragmites Marsh: Silk Purse from Pig’s Ear
CASE STUDY: Cox Creek, Baltimore, Maryland
Challenge: The Maryland Port Administration needed to mitigate for five acres of tidal open-water and wetland impacts associated with the expansion of the Cox Creek dredged material containment facility, located near the mouth of the PatapscoRiver in the BaltimoreHarbor. The challenge presented to Biohabitats was to develop tidal open-water and wetland compensation in an existing area of open-water and Phragmites wetland adjacent to existing tidal waters. An additional challenge was to work around a client – regulatory history of less than optimum communication and cooperation.
Solution: We used our more than 20 years of tidal wetland restoration experience to meet this challenge. First, we had to overcome regulatory misinterpretation regarding the status of the mitigation area as tidal wetlands. We did this by installing three water level dataloggers and documenting that the elevations of the Phragmites wetland and the open-water pond were well above the influence of normal monthly tides. In addition, since the proposed mitigation area was already open water and Phragmites wetland, we had to develop a mitigation approach that resulted in significantly greater tidal open-water and wetland quality/value than the open-water and wetlands at the existing mitigation site and the impacted tidal open-water/wetlands. We accomplished this goal by developing a design that resulted in a mosaic of tidal open water ponds in a complex of tidal wetlands divided among low marsh (Spartina alterniflora), high marsh (Spartina patens), and tidal shrub wetlands. We established a permanent tidal channel to insure tidal exchange with the river, and established upland areas for reforestation. We took this mitigation design to the regulators and gained their support for the approach before finalizing the design and construction documents. We worked with the client to provide construction oversight as a means to insure the project was constructed according to plan, and that any unanticipated situations would be resolved in a manner consistent with our mitigation approach. In addition, a large adjacent Phragmites wetland was treated with herbicide (glysphosate) using helicopter applications as an effort to reduce opportunities for the reintroduction of the Phragmites into the mitigation wetland. The solution not only met all regulatory agency requirements, it also established valuable coastal marsh habitat along the Chesapeake Bay.
A peat-accumulating wetland that has no significant inflows or out flows and will support acidophilic mosses, particularly sphagnum.
The restoration, creation, enhancement, or in exceptional circumstances, preservation of wetlands and/or other aquatic resources for the purpose of compensating for unavoidable adverse impacts.
Creation (of wetlands)
Converting a non-wetland (either dry land or unvegetated water) to a wetland.
The standard unit of measurement for quantifying the net gain in wetland acreage or function that results from wetland restoration, enhancement, creation, or preservation.
Enhancement (of wetlands)
Increasing one or more of the functions performed by an existing wetland beyond what currently or previously existed in the wetland. There is often an accompanying decrease in other functions.
A peat-accumulating wetland that receives some drainage from surrounding mineral soil and usually supports marsh-like vegetation.
Soil that is saturated, flooded, or ponded long enough during the growing season to develop anaerobic conditions in the upper part of the soil.
A wetland that meets the legal definition of a wetland under the Clean Water Act or Swampbuster and is thereby under the jurisdiction of the Corps for regulatory purposes.
A wetland dominated by herbaceous, emergent plants.
A wetland site that encompasses known variation in the functioning of the subclass of wetlands. Reference wetlands are used to establish range of functioning within the subclass.
Restoration (of wetlands)
Returning a degraded wetland or former wetland to a pre-existing condition or as close to that condition as is possible.
Zone immediately adjacent to streams, which is occasionally flooded but otherwise dry for varying portions of the growing season.
A scrub-shrub wetland typifies a community in transition and exemplifies the dynamic nature of wetlands in general. Many emergent wetlands, left undisturbed, will gradually be replaced through succession by woody vegetation.
A wetland dominated by woody plant species including trees and shrubs.
A shallow, intermittently flooded wet meadow that is generally dry for most of the summer or fall.
The land area that drains into a stream, river, or other body of water.
Wetland mitigation banking
Wetland restoration, creation, enhancement, or in exceptional circumstances, preservation undertaken expressly for the purpose of compensating for unavoidable wetland losses in advance of development actions, when such compensation cannot be achieved at the development site or would not be as environmentally beneficial.
Definitions of Wetland Systems from Cowardin, et al. (1979)
Open ocean overlying the continental shelf and associated high-energy coast line. Examples of wetland types within this system are subtidal and intertidal aquatic beds, reefs, and rocky shores.
Deepwater tidal habitats and adjacent tidal wetlands that are usually semi-enclosed by land but have open, partially obstructed, or sporadic access to the ocean and in which ocean water is at least occasionally diluted by freshwater runoff from the land. Examples of estuarine classes include subtidal and intertidal emergent wetlands, forested wetlands, and rock bottom.
Wetland and deepwater habitats contained within a channel with two exceptions: 1) wetlands dominated by trees, shrubs, persistent emergent plants, emergent mosses, or lichens, and 2) habitat with water containing ocean-derived salts in excess of 5 ppt (parts per thousand). Rivers and streams fall within this system and subsystems include tidal, perennial, and intermittent watercourses.
Wetlands and deepwater habitats with all of the following characteristics: 1) situated in a
topographic depression or a dammed river channel, 2) less than 30 percent areal coverage by trees, shrubs, persistent emergent vegetation, emergent mosses, or lichens, and 3) total area exceeds 8 hectares (20 acres). Lakes typify lacustrine wetland systems.
All nontidal wetlands dominated by trees, shrubs, persistent emergent vegetation, emergent mosses or lichens, and all such wetlands that occur in tidal areas where salinity due to ocean-derived salts is below 5 ppt. This system also includes wetlands lacking such vegetation if they are less than 8 hectares, lack wave-action or bedrock shoreline features, and are no deeper than 2 meters at low water in their deepest spot. Examples include ponds, bogs, and prairie potholes.
Biohabitats Projects, Places & People
Biohabitats Opens Great Lakes Bioregion Office
We are proud to announce the opening of a new office to better serve clients in the Great Lakes Bioregion. The office is located in Cleveland, Ohio. Our Bioregion office is poised to assist communities throughout the Great Lakes in river and stream restoration, woodland and savannah restoration, prairie and native grassland restoration as well as watershed management, invasive species management, and ecological sustainable design.
Biohabitats Awarded Contract for Rock Crest Stream Restoration, Rockville, MD
The City of Rockville conducted a watershed management plan for the Rock Creek watershed and found a number of opportunities to enhance existing stormwater management facilities, add new water quality best management practices and to restore degraded stream courses. A reach of Rock Crest, a tributary to Rock Creek, was selected as the first restoration candidate. The City of Rockville selected Biohabitatsto provide preliminary and final design, permitting and construction oversight. l
Georgia Department of Transportation Stream Restoration Workshops, GA
GDOT has contracted with Biohabitatsto offer a 2-week Stream Restoration Workshop. The course will introduce participants to stream assessment techniques, stream classification, stream restoration design, construction, and post construction management. The course combines both classroom training and field exercises. It will be open to GDOT staff as well as local practitioners.
Biohabitats Completes 1st Season of Noxious Weed Inventory in Durango, CO
Biohabitatscompleted the first season of noxious weed mapping and treatment in the San Juan Mountains of Colorado. In conjunction with Land Stewardship, Inc. (Boulder, CO) and Southwest Weed Control, Inc. (Cortez, CO) the Biohabitatsteam surveyed 12,050 acres of the 65,000 acre burn area within the San JuanNational Forest, inventorying 16 different species noxious weeds throughout the forest. All inventory data was collected using the handheld Trimble GeoExplorer 3 units and mapped in ArcMap to enable tracking of the inventory and treatment efforts. It also allowed the team to analyze the effects of fires on noxious weed propagation and to evaluate future noxious weed treatment alternatives following fires.
Biohabitats to Complete Design for North Delaware River Front Greenway-Lardner Point Pilot Project, Philadelphia, PA
Funded through a Coastal Zone Management Grant from NOAA, Biohabitatswill be completing a final design and construction package for the first section of the North Delaware River Front Greenway. The visionary greenway is an effort by the City of Philadelphia and Pennsylvania Environmental Council to reclaim the Delaware River front to provide both an ecological, cultural and economic amenity to the City. Design elements include river front stabilization using tidal wetlands and native riparian plantings, non-tidal wetlands, native meadows, ecologically sustainable site amenities, as well as native riparian habitat.
Construction Supervision for Beaver Creek Stream Restoration, Washington County, MD
Working with Meadville Land Services, Biohabitatswill provide construction supervision for a stream restoration along Beaver Creek in Washington County, Maryland. The Beaver Creek stream restoration consists of the removal of an old mill dam and creation of improved fish habitat along an 800 foot reach of the stream above Beaver Creek Church Road. The existing mill dam provided a barrier that prevented fish from migrating upstream. Upon removal of the mill dam, several cross vanes and other habitat structures will be installed to provide cover and substrate that will be beneficial for the local fish population. Biohabitats, Inc. will be providing construction supervisions services to ensure the proper placement and construction of the in-stream structures.
Leaf Litter is a publication of Biohabitats, Inc. Coinciding with the earth’s biorhythms, it will be published at the Fall Equinox, Winter Solstice, Spring Equinox and Summer Solstice to probe issues relating to ecological restoration. Biohabitats has attempted to ensure the accuracy and veracity of the information provided in Leaf Litter, however, information contained in Leaf Litter should not be construed as a recommendation or endorsement by Biohabitats. Please click here to contact Leaf Litter editors with questions, comments or content ideas.
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Biohabitats is a design and consulting firm specializing in ecological planning, assessment, design, construction oversight, monitoring and outreach. Biohabitats assists government agencies, NGOs and private entities throughout North America with issues related to wetland restoration, conservation biology and restoration ecology. To learn more