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COMPENSATING FOR WETLAND LOSSES UNDER THE CLEAN WATER ACT Appendixes
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COMPENSATING FOR WETLAND LOSSES UNDER THE CLEAN WATER ACT This page in the original is blank.
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COMPENSATING FOR WETLAND LOSSES UNDER THE CLEAN WATER ACT Appendix A Survey of Studies: Comparison of Mitigation and Natural Wetlands
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COMPENSATING FOR WETLAND LOSSES UNDER THE CLEAN WATER ACT TABLE A–1 Survey of Studies: Comparison of Mitigation and Natural Wetlands Region Time Period # Sites Scope Massachusetts 1983 to 1994 114 Vegetation (% cover) Size Hydrology If project was built Portland, Oregon 1987 to 1993 95 Freshwater emergent and open-water wetlands, soil organic matter (SOM), hydrology Orange County, California 1979 to 1993 70 Vegetation, hydrology
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COMPENSATING FOR WETLAND LOSSES UNDER THE CLEAN WATER ACT Findings Reference 79.9% mitigated for impacts <5000 ft2 54.4% noncompliant Brown and Veneman (1998) 70.1% involved impacts to forested wetlands 61.4% designed to produce scrub/shrub 38.6% actually produced no wetlands 36.8% actually produced open wet meadows Plant communities at replication sites differed significantly from wetlands they were designed to replace. Similarity did not increase between new and 12-year-old projects. Compliance but not similarity between replicated and impacted plant communities increased with greater completeness of the replication plan and Order of Conditions. Mean SOM concentrations were higher in naturally occurring wetlands (NOWs) than in mitigating wetlands. Shaffer and Ernst (1999) No significant change in SOM concentration in soils in mitigating wetlands (MWs) sampled. For a subset of wetlands measured for hydrology, there was a significant negative relationship between SOM and the extent of inundation by standing water. Success of mitigation, in terms of SOM, could be improved by better project design and better management of soils during project construction. Thirty of the 70 (43%) met all of their permit conditions and were considered successful; these projects comprised 195 ac. Sudol (1996) Six sites (9%) comprising 52 ac did not meet any of their permit conditions and were considered failures. Mitigation in Orange County has been unsuccessful. There has been a net loss of wetland and riparian habitat.
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COMPENSATING FOR WETLAND LOSSES UNDER THE CLEAN WATER ACT Region Time Period # Sites Scope Portland, Oregon 1993 45 natural 51 mitigation 1–11 years; mean 5 years Small (≤ 2 ha) Freshwater, palustrine wetlands in rapidly urbanizing area Plant species richness (presence/absence) and composition of natural and mitigation wetlands Relationships between floristic characteristics and variables describing land use, site conditions, and mitigation activities Susquehannah River watershed, Pennsylvania 1993 20 reference; 44 created Soil organic matter, matrix chroma, bulk density, total nitrogen, pH Iowa, Minnesota, South Dakota 1989 to 1991 62 Restored prairie potholes Basin morphometry, hydrology, and vegetation zone development
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COMPENSATING FOR WETLAND LOSSES UNDER THE CLEAN WATER ACT Findings Reference Overall species richness was high (365 plant taxa), but >50% of species on both natural and mitigation wetlands were introduced. Magee et al. (1999) Wetlands surrounded by agricultural and commercial/ industrial/transportation corridor uses had more introduced species per site than those surrounded by undeveloped land. Wetlands in the urbanizing study area are floristically degraded. Current wetland management practices are replacing natural marsh and wet meadow systems with ponds, changing composition of plant species assemblages. Compared to reference wetlands, wetland creation projects contained less SOM at 5 cm and unlike reference sites, SOM content was uniform between 5 and 20 cm. Created wetlands contained less silt at 5 cm and more sand and less clay at 20 cm. Wetland creation projects had higher pH, bulk density, and matrix chroma and lower total nitrogen. Bishel-Machung et al. (1996) No relationship was found between time elapsed since construction and soil organic matter content in wetland creation projects. Earthen dams installed on 73% restoration sites. Galatowitsch and van der Valk About 60% of basins had predicted hydrology or held water longer than predicted. (1996) Twenty percent were hydrological failures and either never flooded or had significant structural problems. Most had developed emergent and submersed aquatic vegetation zones, but only a few had developed wet prairie and sedge meadow vegetation zones.
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COMPENSATING FOR WETLAND LOSSES UNDER THE CLEAN WATER ACT Region Time Period # Sites Scope Florida 1990 40 projects Surface hydrology, vegetation Central Florida 1993 10 natural, 10 created Dipterans in freshwater herbaceous wetlands Galveston Bay, Texas Fall 1990, spring 1991 10 created, 5 natural Densities of nekton and infauna in salt marshes
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COMPENSATING FOR WETLAND LOSSES UNDER THE CLEAN WATER ACT Findings Reference Forty of 195 permitted projects had undertaken some type of mitigation activity. Only four of those 40 projects met all the stated permit goals. Twenty-four of the 40 projects contained success criteria, but for 23 (57.5%) of the projects the success criteria were inappropriate. Erwin (1991) Of the 1,058 acres required by permit to be created for all 40 projects, only 530.6 (50%) acres had actually been constructed. Location and persistence were not in the criteria. Twenty-three (57.5%) of the 40 projects were located where surrounding existing or future land uses may prevent the wetlands from providing their intended functional values. Only three projects had a long-term management plan. Twenty-five (62.5%) of the projects had hydrological problems. 32 (80%) projects were colonized by undesirable plant species. Permits for 22 projects required removal of problematic plants, but attempts to control them were undertaken in only 13 (59%) projects. Postconstruction monitoring was required for 39 projects, but adequate monitoring had been undertaken in only 15 (38%). No convincing evidence of differences in natural and created wetland dipteran communities. Streever et al. (1996) Densities of daggerblade grass shrimp were not significantly different among marshes, but the size of these shrimp was significantly smaller than in natural marshes. Minello and Webb (1997) Densities of the marsh grass shrimp and of three commercially important crustaceans were significantly lower in created marshes than in natural marshes. Fish densities in vegetation were significantly lower in created marshes than in natural marshes. Natural and created marshes did not differ in species richness of nekton. Marsh elevation and tidal flooding are key characteristics affecting use by nekton and should be considered in marsh construction projects.
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COMPENSATING FOR WETLAND LOSSES UNDER THE CLEAN WATER ACT Region Time Period # Sites Scope Ohio 1994 to 1995 5 replacement Hydrology, soils, vegetation, wildife, water quality Texas 10 Invertebrates, fish North Carolina 6 Sediment/soil, invertebrates North Carolina 5 Sediment/soil North Carolina Marshes established 1971 to 1974 and monitored for 25 years 2 constructed marshes 2 natural marshes Above-ground biomass, soil, benthic infauna, carbon, total nitrogen South Carolina 2 Sediment/soil, plants, invertebrates, fish Texas 3 Plants, invertebrates, fish California 2 Sediment/soil, plants, fish, topography North Carolina Multiple Plants, invertebrates
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COMPENSATING FOR WETLAND LOSSES UNDER THE CLEAN WATER ACT Findings Reference Eighty percent were in compliance with legal requirements and demonstrated medium-to-high ecosystem success Wilson and Mitsch (1996) Minello and Webb (1997) Sacco et al. (1994) Craft et al. (1988) Constructed marshes: macrophyte community developed quickly and within 5 to 10 years, above-ground biomass and MOM were equivalent or exceeded corresponding values in the natural marshes. Craft et al. (1999) After 15–25 years, benthic infauna and species richness were greater in the natural marshes. Soil bulk density decreased and organic carbon and total nitrogen increased over time in constructed marshes. Nitrogen accumulation was much higher in constructed marshes than in natural marshes. Different ecological attributes develop at different rates, with primary producers achieving equivalence during the first 5 years, followed by the benthic infauna community 5–10 years later. LaSalle et al. (1991) Minello and Zimmerman (1992) Haltiner et al. (1997) Seneca et al. (1976)
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COMPENSATING FOR WETLAND LOSSES UNDER THE CLEAN WATER ACT REFERENCES Bishel-Machung, L., R.P.Brooks, S.S.Yates, and K.L.Hoover. 1996. Soil properties of reference wetlands and wetland creation projects in Pennsylvania. Wetlands, 16(4):532–541. Brown, S., and P.Veneman. 1998. Compensatory wetland mitigation in Massachusetts. Research Bulletin Number 746. Amherst, MA: Massachusetts Agriculture Experiment Station, University of Massachusetts Craft, C, J.Reader, J.N.Sacco, and S.Broome. 1999. Twenty-five years of ecosystem development of constructed Spartina alterniflora (Loisel) marshes. Ecol. Applic. 9(4):1405– 1419. Craft, C.B., S.W.Broome, and E.D.Seneca. 1988. Nitrogen, phosphorus and organic carbon pools in natural and transplanted marsh soils. Estuaries 11(4):272–289. Erwin, K.L. 1991. An Evaluation of Wetland Mitigation in the South Florida. Water Management District, Vol. 1. Methodology. West Palm Beach, FL: South Florida Water Management District. Galatowitsch, S.M., and A.G.van der Valk. 1996. Characteristics of Recently Restored Wetlands in the Prairie Pothole Region. Wetlands 16(1):75–83. Haltiner, J., J.B.Zedler, K.E.Boyer, G.D.Williams, and J.C.Callaway. 1997. Influence of physical processes on the design, functioning and evolution of restored tidal wetlands in California (USA). Wetlands Ecol. Manage. 4(2):73–91. LaSalle, W.M., M.C.Landin, and J.G.Sims. 1991. Evaluation of the flora and fauna of a Spartina alterniflora marsh established on dredged material in Winhay Bay, South Carolina. Wetlands 11(2):191–208. Magee, T.K., T.L.Ernst, M.E.Kentula, M.E. and K.A.Dwire. 1999. Floristic comparison of freshwater wetlands in an urbanizing environment Wetlands 19(3):517–534. Minello, T.J. and J.W.Webb, Jr. 1997. Use of natural and created Spartina alterniflora salt marshes by fishery species and other aquatic fauna in Gavelston Bay, Texas, USA. Mar. Ecol Prog. Ser. 151(1/3):165–179. Minello, T.J., and R.J.Zimmerman. 1992. Utilization of natural and transplanted Texas salt marshes by fish and decapod crustaceans. Mar. Ecol. Prog. Ser. 90(3):273–285. Sacco, J.N., E.D.Seneca, and T.R.Wentworth. 1994. Infaunal community development of artificially established salt marshes in North Carolina. Estuaries 17(2):489–500. Seneca, E.D., L.M.Stroud, U.Blum, and G.R.Noggle. 1976. An Analysis of the Effects of the Brunswick Nuclear Power Plant on the Productivity of Spartina alterniflora (smooth cordgrass) in the Dutchman Creek, Oak Island, Snow's Marsh, and Walden Creek Marshes, Brunswick County, North Carolina, 1975–1976. 3rd Annual Report to Carolina Power and Light. Raleigh, NC: Carolina Power and Light Com. Shaffer, P.W., and T.Ernst. 1999. Distribution of soil organic matter in freshwater emergent open water wetlands in the Portland, Oregon metropolitan area. Wetlands 19(3):505– 516. Streever, W.J., K.M.Portier, and T.L.Crisman. 1996. A comparison of dipterans from ten created and ten natural wetlands Wetlands 16(4):416–428. Sudol, M.F. 1996. Success of Riparian Mitigation as Compensation for Impacts Due to Permits Issued Through Section 404 of the Clean Water Act in Orange County, California. Ph.D. Dissertation. University of California, Los Angeles. Wilson, R.F., and W.J.Mitsch. 1996. Functional assessment of five wetlands constructed to mitigate wetland losses in Ohio. Wetlands 16(4):436–451.
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