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Table 7-7. Review of Wetland Restoration Projects
1 - The Kattegat, Swedish west coast
Wetlands restoration
Vegetation type not specified The Kattegat, a semienclosed, shallow, and
strongly stratified sea area, has experienced increased effects of
eutrophication caused by excessive nitrogen loading. Based on a nitrogen
retention model and denitrification studies, the following hypotheses will be
tested in the wetland restoration program:
- Annual nitrogen retention depends on nitrogen load.
- A decrease in the active surface of a wetland causes an increase in the
nitrogen load and retention per unit area.
- Hydrological loading of a wetland can only be increased to a certain
"critical" level.
- Nitrogen retention is stabilized as a result of newly established plant
communities and sediment formation.
- When nitrogen retention is high, denitrification and sedimentation are the
predominating mechanisms.
- During the winter, high nitrogen load may counteract
low-temperature-limited denitrification.
- If nitrogen transport in a stream is known, retention in a future restored
wetland can be predicted.
This 5-year wetland restoration study was just getting under way in 1991.
Fleischer, S., L. Stibe, and L. Leonardson. 1991. Restoration of Wetlands as
a Means of Reducing Nitrogen Transport to Coastal Waters. Ambio: A Journal
of the Human Environment, 20(6):271-272.
2 - Ballona Channel Wetlands, Marina Del Rey, Los Angeles, California
Wetlands restoration
Vegetation type not specified This paper discusses the model used to plan
stormwater detention for site development, and at the same time to allow
wetland restoration. Flood control, restoration of wetland habitat values, and
quality control of urban stormwater runoff were some objectives of the project.
This paper discusses only the model used to engineer the plan.
Tsihrintzis, V.A., G. Vasarhelyi, W. Trott, and J. Lipa. 1990. Stormwater
Management and Wetland Restoration: Ballona Channel Wetlands. In Hydraulic
Engineering: Volume 2, Proceedings of the 1990 National Conference, pp.
1122-1127.
3 - Banana Lake headwater system, Lakeland, Florida
Restored headwaters (including hardwood and herbaceous wetlands)
As compensation for roadway environmental impacts from the development of a
belt loop around Lakeland, Florida, the restoration of Banana Lake was
initiated in 1983. Development of the project was undertaken by the Polk County
Engineering and Water Resources Division, the Florida Department of
Transportation, and the City of Lakeland. Objectives of the restoration project
include:
- improvement of surface water quality;
- elimination of localized flooding and dangerous roadside ditches;
- restoration of hardwood wetland swamp system;
- restoration of the premining drainage and functions of the headwater
system.
Postrestoration differences are summarized:
- Western basin (average water quality):
- All data in mg/L unless otherwise noted.
- BDL=Below detection limits.
Parameter Change after restoration
Temperature-oC -0.9
pH-units +0.3
DO +1.1
Specific conductance -54 umhos/cm
Nitrate-Nitrate as N to BDL
N, Ammonia to BDL
N, Total Kjeldahl -2.98
N, Total -3.03
Orthophosphate as P -0.974
Phosphorus, Total -0.869
Restoration of the western basin was completed in 1985. The following data
compare the restored western basin water quality to the existing (1989) water
quality in the unrestored eastern ditch.
- Roadside ditch quality - Lakeland Highlands Rd.:
Western Eastern
Basin Basin
Parameter (Restored) (Unrestored)
Temperature (oC) 25.3 22.7
pH-units 7.1 7.1
DO 7.2 7.0
Specific conductance 217 221 umhos/cm
Nitrate-Nitrate as N BDL 0.016
N, Ammonia BDL 0.145
N, Total Kjeldahl 1.03 1.48
N, Total 1.03 1.58
Orthophosphate as P 0.233 0.525
Phosphorus, Total 0.571 1.514
Powers, R.M., and J.F. Spence. 1989. Headwater Restoration: The Key Is
Integrated Project Goals. In Proceedings of the Symposium on Wetlands:
Concerns and Successes, Sept. 17-22, Tampa, Florida, pp. 269-279
4 - Creekside Park, Marin County, California
Wetland restoration
Cordgrass and pickleweed planting In 1972, the U.S. Army Corps of Engineers
placed dredged spoils on the Creekside Park site in conjunction with the
dredging of Corte Madera Creek. As a result of citizen pressure, a report on
the feasibility of creating a salt marsh was prepared in 1973. In 1975, the
site was acquired and a committee of local citizens initiated a park plan.
- In 1975, the Corps of Engineers issued a permit for a small marsh plant
nursery area to provide some initial experience in transplanting cordgrass and
pickleweed within the future marsh area. The permit to excavate for the entire
marsh restoration project was issued in 1976.
- The site plan included removing spoil for channels, grading upland areas
for marsh plant colonization, depositing excess material to create islands and
upland areas, and creation of public access.
- After the first marsh plantings failed to germinate in 1977, a second
attempt was made using a number of different species of cordgrass including
seeds from Humboldt Bay and Spartina marina from England.
No records were kept of success or establishment of marsh plants. However, in
1979, Royston, Hanamoto, Beck and Abbey, the landscape architect responsible
for the project, was given an Award of Excellence by the American Society of
Landscape Architects for the restoration plan.
Josselyn, M., and J. Buchholz. 1984. Marsh Restoration in San Francisco
Bay: A Guide to Design & Planning. Technical Report #3. Tiburon Center
for Environmental Studies, San Francisco State University. 104 pp.
5 - Coyote Creek and Anza-Borrego Desert State Park, San Diego County,
California
Riparian/creek restoration
Until March 1988, all vehicles were allowed to travel on the 29-kilometer
route of Coyote Canyon, including the riverine routes. The jeep trail passed
through the three most significant riparian forests of Coyote Creek and by the
early 1980s the impacts of approximately 1000 vehicles on the riparian system
during busy weekends became too great. An annual seasonal closure of the entire
Coyote Canyon watershed to all persons and vehicles was enacted. A bypass route
now provides permanent protection to one of the three riparian sections. A ban
on all vehicles that are not street legal, including dirt bikes, all-terrain
cycles, and many dune buggies, has caused the traffic corridors to become
filled in with thick stands of willow and tamarisk, which provide additional
avian habitat.
USDA, Forest Service. 1989. Proceedings of the California Riparian
Systems Conference, September 22-24, 1988, Davis, California, pp.
149-152.
6 - Unknown Wetland
This paper presents economically efficient policy reforms of national
wetlands programs that result in enhanced maintenance of wetland stocks and
accommodation of development pressures. The authors' suggestions include a
fixed wetlands development fee for developers building in unprotected areas.
These development tax revenues then would be used to finance a nationwide
investment program to aid the replacement and management of wetlands created to
offset losses to development. Alternatively, developers may choose to implement
their own mitigation plans. According to the authors, this approach would offer
more assurance that coastal wetlands damage will be compensated. Included in
this paper are tables of summaries of costs for the following conditions:
- Wetland creation with dredged material from maintenance of navigation
projects;
- Wetland creation with proposed 25,000- cfs controlled sediment diversions;
and Wetland creation with uncontrolled sediment diversions.
Shabman, L.A., and S.S. Batie. 1987. Mitigating Damages from Coastal
Wetlands Development: Policy, Economics and Financing. Marine Resource
Economics, 4:227-248.
7 - Amana Society Farm, eastern Iowa
Poplar tree buffer strips in riparian zones
This study outlines 2 years of study of Iowa's riparian corridors by the
Leopold Center. Populus spp. (poplar) were planted in buffer strips
along creeks to produce a productive crop and a more stable riparian zone
ecosystem. Planting techniques were developed so that roots grew deep enough to
intercept the surficial water and dense enough to uptake most available
nitrogen before it leached into the stream. During the two growing seasons, the
deep-rooted poplar removed soil nitrate and ammonia nitrogen from soil water
well below Maximum Contaminant Limits.
Tables or graphs for the following data can be found in the paper:
- Tree survival and stem and leaf growth;
- Total Kjheldahl Nitrogen concentrations;
- Nitrate nitrogen concentrations;
- Ammonia nitrogen concentrations; and Total organic carbon
concentrations.
Licht, L.A., and J.L. Schnoor. 1990. Poplar Tree Buffer Strips Grown in
Riparian Zones for Non-point Source Pollution Control and Biomass
Production. Leopold Center for Sustainable Agriculture.
8 - Sweetwater River Wetlands Complex, San Diego Bay, California
Construction and enhancement of salt marsh
Mitigation for lost wetland habitat is being carried out by the California
Department of Transportation. The mitigation marshes include the Connector
Marsh, which is a hydrologic link between Paradise Creek and the Sweetwater
Marsh, and Marisma de Nacion, a 17-acre marsh excavated from the "D Street
fill" in 1990. The assessment study thus far has found that:
- Concentrations of free sulfide were greater in the natural marsh compared
to only trace amounts in the constructed marsh.
- Nitrogen fixation rates were generally twice as high in the natural salt
marsh than in the man-made salt marsh.
- There were two to four times more individuals in a natural marsh at San
Diego Bay than in the 4-year-old man-made marsh. Abundance of species was up to
nine times greater in the natural marsh. These samplings were taken at low
marsh elevations. At elevations of 0.5 m above mean sea level, the numbers of
species and individuals were similar for areas with high cover.
- The preliminary conclusion was that the USFWS criteria for fish species and
abundance have been met by the constructed marsh.
- An overall comparison indicated that the constructed marsh was less than
60% functionally equivalent to the natural reference wetland (Paradise Creek
Marsh) when comparing water quality, plant biomass, and number of species and
individuals.
- The report contains detailed tables that provide the following quantitative
data:
- Pore water concentrations of free sulfides;
- Rates of nitrogen fixation;
- Total nitrogen and phosphorus in sediment core samples;
- Biomass of cordgrass;
- Ammonium levels of pore water samples;
- Mean number of individuals per litterbag;
- Mean number of species per litterbag;
- Number of channel invertebrates found at sampling stations; and
- Sightings of water-associated birds.
Pacific Estuarine Research Laboratory. 1990. A Manual for Assessing Restored
and Natural Coastal Wetlands with Examples from Southern California.
California Sea Grant, La Jolla, California, pp. 19-34. 9 - Connecticut
Created and natural wetlands
This report compares five 3- to 4-year-old created wetland sites with five
nearby natural wetlands of comparable size. Hydrologic, soil, and vegetation
data were compiled over a 2-year period (1988-89). Results indicated that:
- Only one created site appeared to mimic the hydrology of a natural wetland
because of its connection to a natural water source.
- Typical wetland soils exhibiting mottling and organic accumulation were
lacking in created sites.
- Plant cover was higher in the natural sites because of their greater
maturity.
- The created sites exhibited a slightly higher number of species. This
species richness can be attributed to the rapid rate of species establishment
on mineral soil substrates. The small sample size also may have contributed to
the high number of species in the created site. Egler's Initial Floristic
Composition concept, a model of vegetation development, also explains the
difference in species numbers. This model assumes a large number of species
early in the development process, which may decrease over time as a result of
interspecific competition.
- Based on observations of bird species diversity and muskrat activity,
creation of comparable wildlife habitat was achieved at more than one created
site.
The authors concluded that the presence of invasive species threatens the
future of the created wetlands. Confer, S., and W.A. Niering. Undated.
Comparison of Created Freshwater and Natural Emergent Wetlands in Connecticut.
Submitted to Wetland Ecology and Management.
10 - Wyoming
Riparian zones
Along a degraded cold desert stream in Wyoming, instream flow structures
(trash collectors), willow, and beaver are being used to reclaim riparian
habitat. Trash collectors are intended to decrease streamflow velocity, causing
sediment to be deposited as channel bed material. Willows will be used to
stabilize new channel bank deposition. Preliminary results have shown that:
- Trash collectors have survived 1 1/2 years and are trapping sediment.
- Channel bed material is rising.
- Beaver are using trash collectors as support for dams.
- Willow plantings have survived 2 years.
Skinner, Q.D., M.A. Smith, J.L. Dodd, and J.D. Rodgers. Undated. Reversing
Desertification of Riparian Zones Along Cold Desert Streams. pp. 1407-1414.
11 - California
Riparian
Severe storms of 1978 through 1983 caused considerable damage to streams in
California. The Soil Conservation Service used several mechanical and
revegetation techniques to stabilize streambanks and reestablish riparian
vegetation. Results of evaluations of 29 projects are discussed, and
recommendations are made to improve success.
Shultze, R.F., and G.I. Wilcox. 1985. Emergency Measures for Streambank
Stabilization: An Evaluation. In Riparian Ecosystems and Their Management:
Reconciling Conflicting Issues. USDA Forest Service GTR RM-120, pp.
54-58.
12 - Rio Grande River, New Mexico
Riparian
Riparian areas continue to be drastically altered, usually by human
activities. Managers have generally been unsuccessful in using conventional
techniques to replace riparian trees. Experiments with Rio Grande cottonwood,
narrowleaf cottonwood, and Gooding willow have shown that a simple and
inexpensive method for their reestablishment is now available (i.e., placing
large, dormant cuttings into holes predrilled to known depth of the growing
season water table).
Swenson, E.A., and C.L.Mullins. 1985. Revegetating Riparian Trees in
Southwestern Floodplains. In Riparian Ecosystems and Their Management:
Reconciling Conflicting Issues. USDA Forest Service GTR RM-120, pp.
135-138.
13 - Savannah River, South Carolina
Wetland
Principal factors that affect seedling recruitment in mature cypress-tupelo
forests include seed production, microsite availability, and hydrologic regime.
Studies on the Savannah River floodplain in South Carolina show that although
seed production seems adequate, microsite characteristics and water level
changes limit regeneration success. Management of water levels on regulated
streams must account for species regeneration requirements to maintain
floodplain wetland community structure.
Sharitz, R.R., and L.C. Lee. 1985. Limits onregeneration processes in
southeastern riverine wetlands. In Riparian Ecosystems and Their Management:
Reconciling Conflicting Issues. USDA Forest Service GTR RM-120,
pp.139-143.
14 - Niger, West Africa
Riparian
A reforestation project in the Majjia Valley, Niger, was undertaken to
improve the microclimate, to reduce water and wind erosion, and to produce fuel
wood. Windbreaks were planted, wood lots were established, and trees were
distributed to the inhabitants. The windbreaks were effective in reducing wind
velocities and, at times, retained soil moisture. Water consumption by
vegetation in the windbreaks did not affect soil moisture in the agricultural
crop rooting zone. Although fuel wood has not been harvested, agricultural crop
yields in the windbreaks were 125% of those in the control.
Ffolliott, P.F., and R.L. Jemison. 1985. Land use in Majjia Valley, Niger,
West Africa. In Riparian Ecosystems and Their Management: Reconciling
Conflicting Issues. USDA Forest Service GTR RM-120, pp. 470-474.
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