Table 7-7. Review of Wetland Restoration Projects

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.

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:

• mprovement of surface water quality;
• limination of localized flooding and dangerous roadside ditches;
• estoration of hardwood wetland swamp system;
• estoration of the premining drainage and functions of the headwater system.

• 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.

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.

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.

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.

This page last updated October 4, 1999