[From the U.S. Government Printing Office, www.gpo.gov]
- ANNSP12F bward No :w" .4, Net Loss A Methodology For Identifying Potential Wetland Mitigation Sites Using a Geographic Information System A Iv Ilk -01 -1F South Carolina Water Resources Commission Report No. 178 USEPA Report No. EPA904-R-94-001 TD224 .S64T69 1993 Toward No Net Loss A Methodology For Identifying Potential Wetland Mitigation Sites Using a Geographic Information System SCWRC Report No. 178, November 1993 USEPA Report No. EPA904-R-94-001 Cynthia R. Brown Project Manager Floyd 0. Stayner GIS Analyst Christopher L. Page Field Biologist Cynthia A. Aulbach-Smith Consdting Botanist South Carolina Water Resources Commission 1201 Main Street, Suite 1100 Columbia, S.C. 29201 (803) 737-0067 A limited number of this publication is available for distribution. C@J When this supply is depleted contact the National Technical -i-. Inf ormqJjpib@Wkq,"'ElS) tat @;61)A&L-465 0. N % r--q NoAA coastal services center Librc,---' 2234 south Hobson Avenue LLJ CM Charleston, SC 29405-2413 State of South Carolina CAR The Honorable Carroll A. Campbell, Jr., Governor South Carolina Water Resources Commission 2-1 ME Appointed Members CEOs Mr. Lynn H. Youmans, Jr., Chairman Mr. Tom W. Dunaway, 111, Vice-Chairman Agriculture Mr. Ben M. Gramling, III .................................................... Gramling Mr. Lewis Walker ................................................................. Sumter Mr. Lynn H. Youmans, Jr . ................................................... Furman Industry Mr. Ralph A. "Nick" Odom, Jr . .......................................... Rock Hill Mr. Robert M. Rainey . ..................................................... Anderson Mr. Frank B.Winslow ......................................................... Hartsville Municipalities Mr. H.F. "Dick" Crater ........................................................ Gaffney Mr. Tom W. Dunaway, III .................................................. Anderson Vacant Saltwater Mr. Whitemarsh S. Smith ................................................ Charleston Ex Officio Members and Designees Mr. D. Leslie Tindal, Commissioner Mr. John W. Parris, Executive Director S.C. Department of Agriculture S.C. Land Resources Conservation Desig: Mr. David L. Tompkins Commission Desig: Mr. Cary D. Chamblee Mr. Doug Br'yant, Commissioner Mr. Wayne L. Sterling, Director S.C. Department of Health S.C. Department of Commerce and Environmental Control Desig: Mr. O'Neal Laird Desig: Mr. R. Lewis Shaw Mr. J. Hugh Ryan, State Forester Dr. Maxwell Lennon, President S.C. Forestry Commission Clemson University Desig: Dr. Tim Adams Desig: Dr. Earl Hayter Dr. James A. Timmerman, Jr., Executive Director Mr. Daniel P. Fanning, P.E., Executive S.C. Wildlife and Marine Resources Department Director Desig: Mr. Larry D. Cartee S.C. Department of Transportation Desig: Mr. Robert B. Ferrell Staff Alfred H. Vang, Executive Director Hank W. Stallworth, Deputy Director Anne Hale Miglarese, Director of Resource Assessment and Planning Division I Identifying Wetland NIfigafton SItes 11sIng 01S Acknowledgements T his study was prepared with funding from the United States Environmental Protection Agency Region IV office of Wetlands Planning under Cooperative Agreement #CD994081-92-1. It does not necessarily reflect the views of this agency and no official endorsement should be inferred. Several individuals and agencies contributed information and advice important to the development of this study. Their help is greatly appreciated. The U.S. Fish and Wildlife Service, the South Carolina Wildlife and Marine Resources Department, and the South Carolina Department of Health and Environmental Control all provided valuable input in the development of model criteria. Dr. James Gosselink provided extensive review of this project. Danny Johnson of South Carolina Water Resources Commission, Charlie Storrs of the National Wetlands Inventory, and Dennis De Francesco of the Soil Conservation Service offered considerable technical expertise. Hugh Archer of the South Carolina Water Resources Commission and Barbara Postles provided guidance, advice, and sup- port. Roy Newcome of Water Resources Commission provided technical editing of the final document. M Contents Introduction ...................... ...............................................................................................I The issues .............................................................................................................I Value of information .............................................................................................. 2 Model Development . ........................................................................................................ 5 Criteria and data evaluation ..................................................................................... 5 Model components . ............................................................................................... 8 Physical suitability analyses . ............................................................................... 8 Restoration sites . ........................................................................................ 8 Enhancement sites ...................................................................................... 8 Protection sites . .......................................................................................... 9 Opportunity analyses ........................................................................................ 9 Wildlife habitat . .......................................................................................... 9 Justification . ......................................................................................... 9 Criteria . ............................................................................................. 10 Water quality and floodwater storage . .......................................................... 11 Justification ........................................................................................ 11 Criteria .. ............................................................................................ 12 Unique opportunities/barriers and potential threats ............................................. 12 Model Application ......................................................................................................... 15 Study area .......................................................................................................... 15 Automating criteria .............................................................................................. 20 Data preparation ........................................................................................... 20 GIS analyses ................................................................................................. 20 Initial site selection .................................................................................... 20 Wildlife habitat opportunity analysis ............................................................. 22 Water quality/floodwater storage analysis . .................................................... 28 Composite overlay .................................................................................... 32 Unique opportunities/potential threats ......................................................... 32 Model complications/improvements ................................................................. 32 Field-truthing ....................................................................................................... 39 Verification of source data .. ............................................................................. 39 Other observations .. ....................................................................................... 42 Conclusions .................................................................................................................. 43 References . ................................................................................................................... 45 Appendix I - Generalized NWI wetlands used in analyses ..................................................... 49 Appendix 11 - Generalized land use data used in analyses ...................................................... 50 Appendix III - Hydric soils list by county used in analyses ..................................................... 50 V Iblenfifying Wetland Afffigallon 51tes UsIng 01S Figures Figure 1. Flowchart of steps in wildlife habitat analyses ....................................................... 11 Figure 2. Flowchart of steps in water quality and floodwater storage analyses . ....................... 12 Figure 3. Flowchart of steps for identifying optimal mitigation sites . ..................................... 14 Figure 4. Map showing location of Four Hole Swamp sub-basin .......................................... 16 Figure 5. Map showing counties in Four Hole Swamp sub-basin .......................................... 17 Figure 6. Map showing land resource areas in Four Hole Swamp sub-basin ........................... 18 Figure 7. Map of land use/land cover in Four Hole Swamp sub-basin ................................... 19 Figure 8. Map of potential mitigation sites by mitigation class .............................................. 21 Figure 9. Map of core habitat sites .................................................................................. 23 Figure 10. Map of core habitat sites and adjacent degraded sites .......................................... 24 Figure 11. Map showing results of edge elimination analysis ............................................... 25 Figure 12. Map of habitat sites 40 acres or greater ............................................................ 26 Figure 13. Map of all potential wildlife habitat sites ............................................................ 27 Figure 14. Map of potential mitigation sites and stream network .......................................... 29 Figure 15. Map of high-order hydrology sites .................................................................... 30 Figure 16. Map of low-order hydrology sites ..................................................................... 31 Figure 17. Map of potential hydrology sites ...................................................................... 31 Figure 18. Map of all opportunity analyses sites ................................................................ 34 Figure 19. Map of final selected potential mitigation sites .................................................... 35 Figure 20. Map of unique opportunity sites ....................................................................... 36 Figure 21. Map of potential threat sites ............................................................................ 37 Figure 22. Map of hydrologic regime for potential mitigation sites ....................................... 38 Figure 23. Map of isolated field check site ........................................................................ 40 Figure 24. Map of riverine field check site ........................................................................ 41 Table Table 1. Available data coverages . ...................................................................................... 7 V Definition of terms Core habitat sites - all protection NVA sites, protected areas, significant natural area, and/or intact upland forest (excluding pine plantations) Core habitat complex - the complex formed by core habitat sites and contiguous restoration and enhancement sites Enhancement sites - any NWI wetland that is modified (i.e., ditched, drained, impounded, or excavated) In-kind mitigation - a project in which the replacement site has the same species composition as the filled wetland site Mitigation - wetland protection, enhancement, or restoration activities required to compensate for wetland losses permitted under Section 404 of the Clean Water Act Mitigation banking - a system in which the creation, enhancement, restoration, or preservation of wetlands is recognized by a regulatory agency as generating compensation credits allowing the future development of other wetland sites* Mititgation class - type of mitigation (protection, enhancement, or restoration) Off-site mitigation - for this study, mitigation which occurs in a different watershed or project site location On-site mitigation - for this study, mitigation which occurs in the same watershed or project site location Opportunity - the public, cultural, or natural resource benefit a mitigation site could potentially provide Out-of-kind mitigation - a project in which the replacement site has a different species composition than the filled wetland site Physical suitability - potential for successful mitigation based on soil, hydrology, and vegetation characteristics of a site Protected area - public land, including state parks, national wildlife refuges, national forests, etc. Protection sites - any NVA wetland that is not modified (i.e., ditched, drained, impounded, or exca- vated) Restoration sites - agriculture fields with hydric soils (prior converted wetlands) Significant natural area - a high-quality, relatively undisturbed natural community or complex of communities as identified by the Natural Areas Inventory. Threat - sources of pollution that pose a potential threat to successful mitigation. These include nutrient sources, sediment sources, and toxic sources. It is recognized that, in fact, a wetland might be restored or enhanced to ameliorate the consequences of these potential threats. Wetland order - the order assigned to a candidate mitigation site on the basis of the stream order of an associated stream From Environmental Law Institute V IdentIfying wemano, xltlgatlon s1tes LISIng O/S Thelssues Permitted land use, development pressures, and illegal fill activity continue to threaten the viability of our Nation's wetlands. Regulatory safeguards have been established to avoid or minimize the impacts resulting from such activities, but when these "sequencing" steps cannot be taken com- pensatory mitigation is sometimes required to replace the ecological loss resulting from wetland destruction or frag- mentation. I This project proposes a methodology to system- atically locate suitable mitigation sites on the South Carolina Coastal Plain that could potentially contribute to the state's wetland resource. It utilizes a currently available Geographic Introduction Information System (GIS) and 1:24,000-scale information sources to automate the mitigation site evaluation process. The validity of this methodology is a function of the current- ness, scale, and accuracy of available data and the selection criteria used. It can be generalized or focused on the basis of different scale data appropriate to the geographic coverage of the investigation. When designing strategies for mitigation, it is often assumed that area-for-area replacement of the same type of wetland, on-site, will assure that any lost ecological function is offset. However, in-kind mitigation projects are often not available on-site; thus, mitigation is pursued on-site/out-of- kind, off-site/in-kind and finally off-site/out-of-kind. Unfor- tunately, many projects, both on-site and off-site, are frag- mented or unconnected and not defensible in the long run. Thus, conventional approaches to mitigation have the poten- tial to counter the desired goal of "no net loss" of wetland acreage. Furthermore, the ability of a replacement wetland to mimic the ecological function of the filled wetland is often questionable. The goal of "no net loss" of wetland function can also be contradicted. To adequately address the issue of functional replace- ment, the potential mitigation site must first be considered as an integrated component of the landscape, hydrologically linked to all other land uses/land covers within the watershed (Lee and Gosselink, 1988). Thus, sound mitigation strategies require identifying sites that have not only a high physical potential for successful mitigation (i.e., appropriate soils, hydrology, and vegetation), but that also contribute to the overall ecological integrity of the entire watershed. In many instances, off-site/within watershed wetlands best meet these 1 U.S. EPA has adopted the goal of the National Wetlands Policy Forum to achieve no overall net loss of the Nation's remaining wetland base, as defined by acreage and function; and to restore and create wetlands, where feasible, to increase the quality and quantity of the Nation's wetlands resource base. Section 404 permits are evaluated under guidelines that prohibit wetland loss unless all appropriate and practi- cal steps have been taken to minimize and otherwise mitigate impacts on the aquatic ecosystem. A February 1990 MOA between EPAand the Corps of Engineers clarified that mitigation should occur according to the following "sequencing" steps: 1)avoidance of impacts through evaluation of practicable alternatives, 2)minimization; and 3)compen- sation for unavoidable impacts through restoration or creation. Introduction criteria. In identifying these potential mitigation sites, it is necessary to recognize similar characteristics between the Value of Information filled and replacement wetland sites. Because this methodology is especially effective in identifying large complexes of mitigation sites of different Our understanding of how wetland characteristics classes - protection, enhancement, restoration - and of relate to wetland function has greatly increased in the last different community types, it can be a useful tool for several years. Certain large-scale, physical characteristics of identifying potential sites for mitigation banks. It is recog- wetlands, including the size, shape, and position of a wetland nized that the potential drawbacks from mitigation banking site on the landscape, generally support wetland function are quite significant and argued by many environmentalists (Brinson, 1988, Preston and Bedford, 1988; O'Neil et al., and regulatory agencies. Many who oppose mitigation 199 1; Whigham et al., 1988 - Kuenzler, 1989 Jaylor et al., banking often refer not only to ecological concerns but also 1990; Harris and Gosselink, 1990). GIS is a tool that can to shortcomings that relate more to institutional factors. be used by regulators and managers to help identify and Conversely, the economic and ecological advantages of evaluate these landscape-scale characteristics. The GIS using established mitigation banks to offset the impacts of a methodology proposed in this study broadly identifies com- particular development project, or for offering credits to plexes of wetlands within a hydrologic unit that are physically compensate for future wetland impacts, can also be strongly amenable to restoration, enhancement, or protection. Sites argued. In spite of the complex issues surrounding mitigation determined to be physically suitable for wetland mitigation banking, the concept appears to be gaining general accep- are segregated into community type and further evaluated to tance as a viable alternative for mitigating the consequences determine their potential to provide "opportunity", or social/ of wetland loss and fragmentation. Indeed, recent directives ecological benefits, and to assess threats that may influence from the Clinton administration endorse the use of mitigation the utility of the site. The opportunities considered in this banks as a means of offsetting wetland loss: study include a site's potential to contribute to 1) wildlife 464 habitat on the basis of fragmentation, size, and extent of While a number of technical and procedural interior habitat; and 2) water quality and floodwater storage questions regarding the establishment and on the basis of hydrologic connectivity and position on the long term management of mitigation banks landscape. Other opportunity analyses require consider- remain, conceptually mitigation banking, ation of known locations of endangered/threatened/rare with appropriate environment safeguards, species habitat and significant natural areas, as well as cultural offers numerous advantages. Banking resources. Threats are identified in this study as potential provides for greater certainty of successful toxic, nutrient, or sediment sources and include mines, compensatory mitigation in the permit hazardous waste sites, and industrial and domestic waste process by requiring mitigation to be landfills. The Four Hole Swamp sub-basin in South Carolina established before permits are issued. is then used as a case study for application of this model. Banks are often ecologically advantageous because they consolidate fragmented Wetland mitigation sites identified by this methodology wetland mitigation projects into one large can be reported by community type, size, watershed location, contiguous parcel that can more effectively and potential opportunity contribution. This infonnation can replace the lost wetland functions within the help managers and regulators identify complexes of in-kind watershed. Mitigation banks also provide a mitigation areas within the same watershed as the filled framework for financial resources, planning wetland and, with information provided by the opportunity and technical expertise to be brought analyses, make an initial judgment about a site's potential to together in a fashion often not possible with replace lost wetland functions. Potential mitigation sites smaller mitigation projects. 99 indicated by this methodology might be more thoroughly assessed by descriptive methods of functional evaluation such (White House Office of Environmental as the Habitat Evaluation Procedures (HEP) or the Wetlands Policy, 1993) Evaluation Technique (WET)2 to better determine opportu- nity potential. Thus, this model can be used as an initial This study is not intended to be a treatise on mitigation screening tool for directing mitigation decisions and can banking. It does, however, support the notion that ecological augment the best professional judgment of natural resource benefits can be derived from restoring, enhancing and/or managers and regulators when choosing wetland mitigation protecting large wetland complexes, given that mitigation is sites. opted for only after the appropriate sequencing steps have 2These methodologies, developed by the Fish and Wildlife Service and taken place. Corps of Engineers, respectively, are popular tools used for site- Presently, no national policies or regulations exist to specific functional evaluations. HEP's objective isto determine habitat insure that ecological factors are incorporated into mitigation suitability (both wetlands and uplands) for a variety of species by bank siting decisions. However, guidance clocurnents pro- examining habitat features for these species. WET can be employed to duced by various federal and state regulatory agencies do evaluate the variety of functions provided by wetlands. exist that define, with varying degrees of specificity and 2 IdentIfYing weth?nd NIN98tion Sites I/Sing G/S prioritization, mitigation banking criteria (Environmental fowl Management Plans, State Comprehensive Outdoor Law Institute, 1993). It can be reasonably anticipated that, Recreation Plans, and the Wetlands Reserve Program. In given the recent administrative directives, these guidance general, these federal and state sponsored wetland protec- documents will eventually gain specificity or be replaced with tion strategies are aimed at preserving the array of wetland regulations on mitigation banking. In general, certain com- functions through restoration, planning, or acquisition initia- mon recommendations addressing ecological considerations tives (World Wildlife Fund, 1992). Several existing coopera- emerge from the documentation that exists. These include: tive efforts demonstrate the benefits to be gained from the integration of program objectives. The Nature Conservancy � soil type and water availability offices in North Carolina and Louisiana, for example, have both entered into Memoranda of Agreements with various � existing resource value, size, location state and federal regulatory and development agencies on separate initiatives that achieve the goal of endangered or � presence of contaminants threatened species protection while providing wetland banks from which mitigation credits can be credited and debited � location in same watershed as impact areas (personal communications; Merrill Lynch, North Carolina Nature Conservancy and David Pashley, Louisiana Nature � location on former wetland site Conservancy). � adjacency to high-value habitat protected from Finally, this methodology is not meant, nor does it have future development and compatibly managed the capability, to replace established functional assessment methodologies. It is valuable for making initial identifications � habitat for rare or threatened species (Environ- of potential mitigation sites on the basis of broad character- mental Law Institute, 1993) istics indicative of function. As assessment approaches such as the Hydrogeomorphic Classification SysteM3 are verified In this proposed methodology, all of the above consid- and improved upon, it is possible that a methodology such as erations are incorporated to varying degrees in the identifica- the one suggested in this study could aid in the identification tion of potential wetland mitigation sites. More complete, of functional values on the basis of hydrogeomorphic char- accurate, and current data can be used to provide a finer filter acteristics - characteristics that, given sufficiently detailed for the GIS application proposed. The degree to which any data, could be modeled in a geographic information system. factor is included or excluded must be analyzed against available data sources. Apart from the goal of replacing lost value resulting from wetland permitting activity, identifying mitigation com- plexes with this methodology can also contribute to strategi- 3The Hydrogeomorphic Classification System is a recently developed cally broader ecological goals. For example, information classification too] that relies on general hydrologic and geomorphic obtained from these analyses can be useful in achieving the principles as indicators of abiotic function. A survey of these features protection objectives of other planning and conservation results in a wetland profile which is intended to provide, with expert efforts such as Habitat Conservation Plans, Water Quality/ interpretation, information on the functions provided by a regionally Watershed Management Strategies, North American Water- representative wetland. Introdoction 3 Criteria and Data Evaluation In the first stage of model development, several state and federal regulatory and natural resource agencies were contacted and asked to list the qualities a site should possess (or not possess) to qualify as a potential mitigation site. A literature search was also undertaken to further identify qualities that increase the likelihood of a site to accomplish mitigation goals. The literature also revealed that no such GIS application has been employed elsewhere to identify poten- Model tial mitigation sites. From the suggestions provided through agency comments and from the criteria gathered through the literature search, it became apparent that a wide spectrum of Development factors must be considered in identifying mitigation sites. In general, the factors relate to one or more of the following: � The mitigation potential a site possesses on the basis of physical characteristics. � The mitigation potential a site possesses (or lacks) on the basis of identifiable threats. � The opportunity for public or natural resource benefit that a site, if mitigated, would provide. � The political or legal logistics that mitigation of a particular site would present. EXAMPLE OF MITIGATION CRITERIA FROM REGULATORY AND NATURAL RESOURCE AGENCIES 01- M, A,i wv'ng'- IyOdel '00VOPMeflt 5 In order to determine data availability and suitability, data are derived frorn existing topographic maps that, in the and thus what criteria were realistic to consider, the data were Edisto River Basin, range in date from 1960 to 1989. No inventoried. These data were developed by the South attempt has been made to update any of the older digital data. Carolina Water Resources Commission (SCWRQ as part of the Natural Resources Decision Support System (NRDSS) The significant natural areas data layer was developed project that began in 1988 (Hale et al., 1991). One of the as a result of the Natural Areas Inventory, a study sponsored objectives of the project was to develop a GIS to provide by the National Oceanic and Atmospheric Administration products and services to support natural resource manage- and conducted by the South Carolina Water Resources ment decisions. Commission and The Nature Conservancy (White, 1993). In this study, natural areas of particular ecological significance Each data layer used in this study adheres to accepted were delineated by using NAPP photography and field national data classification systems and mapping standards verified by overflights and ground surveys. The final sites as established by various Federal programs. These include were then digitized by the SCWRC. The purpose of this the U.S. Geological Survey's (USGS) National Mapping systematic survey was to identify sites in the Edisto River basin Division's Digital Line Graph (DLG) program, U.S. Fish and with relatively undisturbed, high-quality natural communities. Wildlife Service's National Wetlands Inventory (NWI) pro- gram, and the Soil Conservation Service's (SCS) county soils Other data layers available for this study include domes- mapping program. AJI data are based on the 1:24,000 scale tic waste permits, industrial waste permits, hazardous waste USGS topographic map series. The digital data are regis- sites, archaeology sites, historic sites, sensitive species and tered to common geographic registration coordinates, insur- communities of concern sites, and mining and reclamation ing comparability of various data layers in scientific analyses. sites. All these data were obtained from the agencies responsible for the particular pennitting activities. Table 1 The layers of primary importance to this study are lists the available data coverages that were considered appro- wetlands, land use, soils, roads, hydrography, and significant priate for this study. natural areas. The wetlands data are derived from 1:40,000 color infrared National Aerial Photography Program (NAPP) After considering the suggested criteria and evaluating photography captured in 1989. Wetlands delineations are the available data, three general model components suitable classified according to the Cowardin classification system for GIS analysis were developed: developed by the NWI (Cowardin et al., 1979). For the purposes of this study, the wetland classifications are simpli- 0 physical suitability fied to several categories of community types (Appendix 1). 0 opportunity potential on the basis of watershed The land use data are photointerpreted in conjunction characteristics with the wetlands data. Land use is mapped for all upland areas, or those areas not classified as wetlands. These data 0 identified threats and unique opportunities are classified to Level 11 of the Anderson classification system (Anderson, 1976). The land use categories are also simpli- Logistical considerations, such as availability for acqui- fied to several community types for use in this study (Appen- sition and number of landowners, were beyond the scope of dix 11). this study. However, these could be considered if more detailed spatial data themes covering these elements were The soils data are derived from standard SCS county available (e.g. parcel maps, real estate data). Also beyond the soils maps. A hydric attribute was added to label those soils scope of this study was consideration of those criteria that have hydric characteristics as defined for each county by requiring site-specific data such as detailed soils information SCS. The hydric soils category used in this study was reduced (rooting volume, fertility), site geology, and detailed elevation substantially (Appendix 111) to include only those with little or differences. It should be emphasized that this proposal no agricultural productivity potential as determined by state establishes a practical methodology for identifying potential soil scientists . mitigation sites while recognizing reasonable expectations of spatial data themes and data scale availability. The findings The roads and hydrography are standard USGS are intended to serve as a rough filter for the initial identifica- 1:24,000-scale (DLG) products. Several attributes were tion of potential mitigation sites on the basis of general added to the DLG data by SCWRC, including drainage order, physical characteristics and position on the landscape. Thus, which is pertinent to this study. All streams in the hydrogra- it directs mitigation efforts on the basis of landscape charac- phy data layer were ordered by using the Strahler method of teristics. It is recognized that site-specific data would be stream ordering (Strahler, 1952). The SCWRC employs required to ultimately deten-nine the potential for mitigation several quality control procedures on the data to correct success at a given site. As supported by Preston and Bedford various problems with the original digital data. These (1988), this analysis takes a qualitative, synoptic approach, procedures include edgematching and attribute correction considering "intrinsic and landscape-levelwetland attributes." where possible. One problem with the DLG data that could This approach reflects, in part, the methodology suggested not be corrected was the datedness of some maps. The digital by Leibowitz et al. (1992) in that it employs a "landscape 6 IdentifYIng Wetl8nd Nitig8tion sites 11sing G/S Table 1. Available data coverages COVERAGE SOURCE SPATIAL DATA TYPE South Carolina Land Resources polygon Mining and reclamation Conservation Commission Hazardous wastes treatment, South Carolina Department of storage and disposal Health and Environmental point Control All landfills South Carolina Department of Health and Environmental point Control South Carolina Institute of polygon Archaeology Archaeology and Anthropology South Carolina Department of National Register of Historic Archives & History, U.S. De- polygon/point Places partment of the Interior Protected areas (government U.S. Geological Survey topo- polygon parks, forests, refuges) graphic quadrangle maps Sensitive species and South Carolina Wildlife and point communities of concern Marine Resources Department Digital line graphs (separate U.S. Geological Survey topo- line coverages for roads, graphic quadrangle maps hydrography) Soil Conservation Service topo- Soils graphic quadrangle maps polygon 1989 NAPP 1:40000 photography, Land use 10-acre resolution, South Caro- polygon lina Water Resources Commission 1989 NAPP 1:40000 photography, Wetlands 1-acre resolution, National Wet- lands Inventory, U.S. Fish and polygon Wildlife Service 1989 NAPP 1:40000 photography, Natural Areas Inventory South Carolina Water Resources polygon Commission approach" using existing data 3) further assess the opportunity a site provides (or potential limitations it poses) by identifying unique The sequence of analytical steps used to address the cultural or public benefits (e.g. endangered species, model components is as follows: historic/archaeologic sites) and assess the threats (e.g. nearby mines, landfills) that may diminish a 1) identify wetlands (by community type and watershed)that site's long term mitigation potential. are physically amenable to mitigation; then The exact procedures and rationale used to develop 2) evaluate the opportunity potential of these sites to each of these model components are described in the provide public benefits through either improved following section. wildlife habitat, water quality enhancement or flood- water storage; and finally mOdel OevelOmeflt 7 converted - are termed prior converted (PC) wetlands in Model Components this study.4 Physical Suitability Analysis - DEFINING RESTORATION SITES defining mitigation classes Segregate soils data according td hydiric.' In conducting the physical suitability analysis, three characteristic. types of potential mitigation classes are identified: restora- Determine', mitigation potential on the basis tion and enhancement sites, which possess potential for of agrid Iultural productivity of soil. wetland reestablishment and protection sites, which repre- Identify, agriculture areas in Anderson level IIf sent viable, functioning wetlands important to the ecological land use maps. landscape. Overlay selected hydric soils with agriculture Restoration Sites polygons. The Environmental Protection Agency (EPA), in its Identify the hydric soils that -'correslpollidto 1993 draft mitigation banking guidance, defined wetland agriculture areas.' restoration as the, "process of returning a significantly These corresponding areas represontprior disturbed or totally altered site to its previously existing converted (PC) wetlands, Qr1he 'at potont* functional wetland condition by some action of man (e.g., restora n- Sites. prior converted cropland or farmed wetlands reestablished as bottomland hardwood forested wetlands)." As mentioned Enhancement Sites previously, this model is intended to indicate potential miti- The draft mitigation banking guidance document is- gation sites on the Coastal Plain of South Carolina. Here, as sued in 1993 by EPA defined wetland enhancement as "the in much of the Southeast Coastal Plain, acre upon acre of improvement or addition of one or more functions to an wetlands have been drained and converted to various land existing wetland or other aquatic habitat (e. g., re-introduction uses including silviculture, agriculture, and pastureland. of natural meanders to a channelized stream system, instal- Currently, mitigation efforts in the Southeast often involve lation of water control structures, planting of desirable restoration of marginal agriculture lands to wetlands (per- species, control of exotics, creation of marsh from open sonal communication, Dr. Russell Lea, Hardwood Research water habitat)." Cooperative, North Carolina State University). These lands typically occur on the margins of flood plains where the In order to identify sites suitable for enhancement, the hydrologic regime is unpredictable. Frequent flooding makes digital version of the 1989 NVA data are analyzed to identify these areas effectively unproductive for agriculture; thus, areas that have been altered to some extent by dikes, farmers are often willing to allow their property to be restored impoundments, excavations, drains, or ditches. Only those to an original 56ttomland hardwood community, for ex- areas that support hydrophytic vegetation (i.e., palustrine ample, and have future use restricted by perpetual conserva- emergent, palustrine scrub shrub, palustrine forested) are tion easements or other transfers of development rights. included in this analysis. Interpretation of the alphanumeric NWI code can often lend insight into community type or land In this study, potential restoration sites are identified use at the time of image capture. For example, excavated according to the following progression. Hydric soils, as areas, defined by Cowardin et al. (1979) as areas that "lie defined for each county by the SCS, include those soils for within a basin or channel excavated by man, " likely represent which the entire mapped area is identified as hydric. These abandoned gravel pits, large ditches, or the occasional areas are further analyzed to determine mitigation potential sewage treatment pond. Impounded areas, defined as areas on the basis of soil productivity as derived from the SCS Land "created or modified by a barrier or dam which purposefully Capability Classes. Only those soils with low reported crop or unintentionally obstructs the outflow of water," likely yields are given consideration in this study. State soil represent wetlands associated with dams, stock ponds, or scientists have further reduced the list of potential soil types some other type of impoundment. Diked areas are defined to those that have extremely limited or no agricultural by Cowardin as areas that are "created or modified by a man- productivity. made barrier or dike designed to obstruct the inflow of water." Partly drained areas exist where "the water level has Next, agricultural areas are identified in the Anderson been artificially lowered, but the area is still classified as level 11 land use data layer and overlaid with the hydric soils wetland because soil moisture is sufficient to support hydro- data to find corresponding areas. The agricultural areas that are identified as hydric are assumed, in this methodology, to 4These wetland classifications were developed by the Agriculture represent wetlands that have been converted to cropland. It Department's Soil Conservation Service. Because this study is not is not possible with the available data to identify when these concerned with regulatory distinctions, these classes are considered areas were actually converted to cropland or the degree of one and the same. flooding; thus, all such wetlands - farmed, prior converted, 8 Identifying Wetland Nitig8tlon Slies Using 01S phytes. Drained areas are not considered wetlands if they can SUMMARY OF MITIGATION CLASSES no longer support hydrophytes." It should be noted that wetland vegetation may remain for decades after drainage. Thus, even though hydrologically altered wetlands support hydrophytic vegetation, changes in hydroperiod imply changes in wetland function (Brinson, 1988). Although these systems are characterized as wetlands, restoring their hydrology could prevent the inevitable conversion to a system characteristic of drier soils. In general, it has been suggested that most ditched/partially drained sites likely represent silviculture areas or abandoned agriculture fields. In some instances, the surrounding flood plain of a channelized stream might also qualify (personal communication, Charlie Storrs, U.S. Fish and Wildlife Service). All modified areas are given consider- Opportunity Analyses ation in this methodology if they support hydrophytic vegeta- determining the benefits tion as mentioned. Opportunity analyses are performed in order to evalu- It is recognized that some modified wetlands, as defined ate the potential that an identified candidate mitigation site in this study, might actually qualify as restoration sites, owing might have in providing public, natural, or cultural benefits on to the loss of wetland function. Determining the degree of the basis of watershed characteristics. The opportunities, or this loss would require a site investigation. benefits, considered for these analyses are wildlife habitat, water quality, and floodwater storage. DEFINING ENHANCEMENT SITES Wildlife Habitat The following discussion provides a rationale, as sup- A# ported by researched literature, for the choice of criteria used to evaluate the potential of candidate mitigation sites to _@' "'Movlo provide wildlife habitat. Justification - Many native species populations are in decline in South Carolina, as in other parts of the Protection Sites country. While population decline is attributable to a variety of causes, habitat encroachment is one of the most signifi- Protection sights include all NWI wetlands that theoreti- cant. Reduction in biological diversity and species quantity is cally have not been modified as described above. For directly related to the reduction in total area available for purposes of this analysis it is assumed that these wetlands are wildlife habitat. This is especially true for far-ranging species fully functional jurisdictional wetlands that are crucial in requiring extensive tracts of land. For example, data available providing habitat, maintaining water quality, and sustaining for the Edisto River basin on the South Carolina Coastal proper hydrologic function. Ecologically, these sites are Plain, suggest that high-level carnivores (and omnivores) extremely important. While jurisdictional wetlands are pro- including the eastern cougar, the black bear, and the red wolf tected through federal and state permit programs, some are have been extirpated from the region (Marshall, 1993). in fact subject to management practices that, in some cases, Landscape fragmentation is another factor contributing to pose a threat to the site's ecological integrity.5 It can be population decline. The resulting subpopulations are iso- assumed that preservation of these viable areas is a desirable lated, leading to increased inbreeding and reduced fecundity. component of a mitigation plan. Also, the proposed Also, several species utilize a range of habitats during their life methodology requires that connected mitigation sites be cycle or seasonally. The elimination of any single habitat identified according to the status and position of currently could have a negative impact on population size. The existing, functional wetlands. Thus, it is necessary to identify conversion of much of the natural forest cover in South these unmodified wetlands in order to perform proximal Carolina to pine plantation is also likely to be responsible for analyses. species decline. Studies show that a change in forest structure from complex natural stands to a monoculture system dramatically affects species composition. (Langley 5For example, important exceptions to the protection authority under and Shure, 1980; Harris et al., 1975; Noble and Hamilton, �404(f) include 1)normal (ongoing) farming, silviculture, and ranching 1975). practices; 2)maintenance and emergency reconstruction of dikes, dams and similar structures; 3)construction or maintenance of farm Noss (1983) argues that habitat diversity, a measure of ponds and irrigation ditches, and maintenance of drainage ditches; ecosystem integrity, can only be achieved through manage- 4)construction of temporary sedimentation basins; and, 5)construc- ment strategies that are comprehensive in scope, consider- tion or maintenance of farm, forest, mining, and othertemporary roads. ing isolated preserves in the context of a fragmented land- Model Development 9 scape. As Harris (1985) points out, a collection of parts is Areas as identified by the Natural Areas Inventory. The very different from a functional system. He contends that Natural Areas Inventory was a study sponsored by the isolated habitat islands, such as the isolated wetlands found National Oceanic and Atmospheric Administration and on the Coastal Plain, could be transfon-ned into an "inte- conducted by the South Carolina Water Resources Commis- grated island archipelago system" if a passageway between sion and The Nature Conservancy. The purpose of this patches was secured. It is feasible that these scattered isolated systematic survey was to identify sites in the Edisto River basin wetlands might be connected by the large stretches of - the larger drainage system of which Four Hole Swamp is contiguous strearnside habitat, or riparian corridors, that a component - with relatively undisturbed, high-quality exist in many areas of the Coastal Plain. Streamside buffers natural communities. Thus, Natural Areas Inventory data provide permanent habitat for a myriad of plant and less far- exist for the study area selected for model application. Such ranging animal species. Many mast-producing plant species data do not exist for other basins in the South Carolina occur in the riparian zone, thus providing a consistent food Coastal Plain. source in many streamside habitats. Also, because of adequate soil moisture and the aerobic conditions existing in Contiguous enhancement and restoration sites that, if many riparian ecosystems, decomposition is rapid in riparian mitigated, would extend the acreage of these core habitat zones and nutrients are readily available to both the terrestrial sites are then identified. This association of core habitat sites and aquatic food chains. As Forman and Godron (1981) and contiguous mitigation sites is termed "habitat complex. " noted, however, many species cannot survive the seasonal Identified habitat complexes as well as contiguous mitigation flooding or wet soils characteristic of lowlands and must have sites (without associated core habitat sites) are further ana- an associated well-drained upland area on which to seek lyzed to determine optimal wildlife habitat on the basis of refuge. ffiree criteria: fragmentation, extent of interior habitat, and size. Oftentimes, the species that are better able to adjust to barriers posed by fragmentation and isolation are in less need All habitat complexes and potential mitigation sites are of protection. As previously stated, populations of large, far- evaluated for fragmentation by considering the existence of ranging species are declining in the region. Interestingly, paved roads. Large multilane or divided highways pose there seems to be a healthy abundance of species more significant barriers to wildlife movement. These highways characteristic of edge/field habitat, such as deer (Marshall, are overlaid on the selected habitat sites to further divide the 1993). As supported by Diamond (1976), Noss (1983), sites and determine true habitat boundaries. Forman and Godron (1981), and Saunders et al. (1991), mitigation strategies should consider habitat needs for those The existence of edge habitat is ubiquitous across the species less adaptable to human-induced perturbations on landscape; it can therefore be argued that habitat needs for the landscape and thus should place priority on large intact edge species are already met by the existing landscape sites with a large proportion of interior habitat and areas conditions. Thus, the habitat complexes meeting the above providing habitat connectivity. criteria are further analyzed to determine conditions support- ing good interior habitat. In this analysis, the complex Criteria - Many of the criteria used to identify boundaries are reduced by 328 feet (100 meters) to deter- mitigation sites in this analysis are based on properties mine interior habitat (Temple, 1986; from O'Neil et al., espoused by Harris (1984) as important for wildlife habitat 1990). It is theorized that this distance effectively represents and include total habitat area, interior habitat extent, and the edge habitat. If any of the complex remains after reduction, distribution of habitat patches in relation to one another and it can be assumed that the complex provides some interior drainage patterns in the watershed. habitat function. The habitat sites remaining after reduction are expanded back to their original boundaries. Mitigation sites that are optimal for wildlife habitat are identified by first defining core habitat sites and then identi- Finally, only habitat complexes of at least 40 acres in fying contiguous enhancement and restoration sites. Core size are considered for the rest of the habitat analysis habitat sites are defined in this study as all unmodified wetland (Adamus, 1987). Also considered are all enhancement and sites (protection sites), as well as a intact upland forests restoration sites that are not part of a habitat complex but that (excluding pine plantations), protected areas (i.e. wildlife are at least 40 acres in size. refuges, state parks, national forests), and Significant Natural 10 Identifying Wetland Afifigstion Sites Using GIS orest, g pine ns nt Determine Reestablish reas fragmentation of extent of rem Core habitat complex by complexes b habitat overlaying multi-lane buffering 32 sites and divided roads (100 meters) cted areas Optimal ,7V Wildlife Identify contiguous modified Buffer inward 328 Eliminate all Habitat Protection NWI and PC wetland sites feet (100 meters) habitat sites mitigation sites and define habitat complex to determine complexes less (unmodified NWI extent of interior than 40 acres wetlands) habitat Figure 1. Steps in wildlife habitat analyses Water Quality and Floodwater Storage among the three. In general, basin or depressional wetlands The following discussion provides a rationale, as sup- receive runoff from a relatively small area since they are most ported by researched literature, for the choice of criteria used often located in headwater areas. Soils in these areas are to evaluate the potential of candidate mitigation sites to generally well suited to assimilate nutrients; however, be- provide water quality and floodwater storage function. cause of their location it is often the case that little water actually flows through them, and opportunity for nutrient Justification - Because wetland systems are ex- transformation is low compared to the other wetland types. tremely variable in structural characteristics, it is difficult to Consequently, they might be considered more valuable as identify unifying concepts that would allow a convenient wildlife habitat than as nutrient assimilation zones. Riverine breakdown of wetland types on the basis of water quality or wetlands, because of their extensive association with upland hydrologic function. Hydrology, for example, is influenced systems and the nature of their soils, have both high capacity by such site-specific characteristics as 1) site geometry, which and opportunity to positively impact water quality and store determines storage capacity; 2) microtopographic relief or floodflow. Because of this, and because of their abundance "roughness," which determines flow velocity and duration; 3) in the South Carolina Coastal Plain, these wetland sites are vegetation, which influences evaporation/transpiration and, given sole consideration in the water quality and floodwater therefore, flood duration; and 4) soil properties, such as storage analyses. Fringe wetlands, or those occurring permeability, which influence water routing (Gosselink et al., adjacent to large bodies of water or at the base of a drainage 1990). There are also site-specific characteristics, many of system (e.g., tidal marsh), are small compared to the large which are closely tied or identical to those above, that largely bodies of water that flush them. Fringe wetlands do not influence a site's ability to serve a water quality enhancement compose a major portion of the selected sub-basin and were function. Stich characteristics include slope, sinuosity, water not given independent treatment in this study. While the velocity on tract, stem density, soil clay and organic matter above described relationships generally hold across geo- content, and loading rates (Scott et al., 1990). As mentioned graphic regions, it is recognized that some exceptions may previously, it is not the intent of this model to definitively apply to a particular region. Thus, for application in other characterize the effectiveness of a site in performing a water areas, the presence and function of isolated or fringe wet- quality or hydrologic function according to such site-specific lands may demand a more thorough consideration of their characteristics. Rather, it is recognized that there also exist contribution to water quality and floodflow storage. watershed level characteristics that influence a site's potential to serve these functions. The primary characteristics consid- Not only is watershed position an important deterrninant ered in this analysis are hydrologic and watershed position, of a wetland's opportunity to contribute to water quality, but it as discussed below. can also be argued that its position along a drainage network dictates its opportunity to contribute to water quality (Kuenzier, Wetland location within a watershed is an important 1989; Brinson, 1988, Whigharn et al., 1988). Potential flood determinant of its contribution to water quality. Brinson storage capabilites are also linked to fl-tis charactenstic. Brinson e al , 11 'es less acres (1988) contended that the geornorphological setting of three (1988) distinguishes between two transport vectors forwater and wefland categories - basin, fringe and riverine - is the nutrients - riparian transport and overbank transport - with driving factor contributing to water quality impact because of one mode of transport dominating over the other depending on differences in hydroperiod, hydrologic energy, and nutrients stream order. Riparian transport, or overland water rurioff, from MOM DeV01OPMON 11 agriculture, urban and silviculture areas first encounters wetlands wetlands represent those that might have the greatest opportu- associated with small order streams. It is here that a majority of nity to store floodflow while effectively removing pollutants from the nutrients and sediments resulting from these land uses settle floodwaters. out and are recycled. Also, runoff is attenuated in these wetlands, helping to alleviate dowristream flooding. Those wetlands Hydrologic connectivityof allother riverine mitigation sites immediately adjacent to a stream have an even greater opportu- is then determined by identifying sites that are adjacent to the sites nityto remove pollutants beforethey are introduced intothewater adjacent to a stream (as defined in above paragraph). AD column. Research supports the notion that, with some excep- comectedsitesaredassifiedaccordingtotheirassociatedwefland tions, the percentage of overland runoff that contacts wetland and termed secondary wetlands. The steps involved in the water environments decreases as stream order increases. Thus, with quality/hydrology opportunity analyses are summarized in some exceptions, low-order wetlands have a greater opportunity Figure 2. toenhancewaterquaWthandohgherorderweflands"gham et al., 1988; KuenzIer, 1989). These riparian areas are Unique Opportunities/Barriers and Poten- particularly important in an agricultural landscape such as the tial Threats - locating endangered Four Hole Swamp sub-basin (from Wf-Agham et al., 1988; Peterjohn and Correll, 1984). species, cultural resources, and potential Iri higher order wetlands the dominant transport vector is contaminant sources overbank flow. In general, these downstream wetland systems, Endangered species habitat and cultural resource sites especially if immediately adjacent to a stream, have greater (archaeologic/historic sites) represent important public re- opportunity to store excess strearnflow during peak events sources and benefit from some protection provided by state (I'aylor et al., 1990; Harris and Gosselink, 1990). It is also and federal programs. Sites containing these resources may recognized that a pollutant removal fuinction will subsequently or may not be optimal for mitigation. The impact, either result from water storage. negative or positive, of a mitigation project on these re- sources should be determined on a site-specific basis. These Criteria - In this analysis, a riverine wetland mitigation sites are identified and overlaid on the final composite, sites immediately adjacent to a stream, as delineated on the DLGs, created by overlaying the results of the habitat and water are identified. To detem-une wetland adjacency, streams are quality/floodwater storage analyses. buffered 98.4 feet (30 meters) on both sides, and sites falling In many instances, cultural and endangered species within the resulting polygon are identified. These areas, because inventories have primarily been done in areas where devel- of their adjacency, are considered primary sites for hydrology and opment has occured. While occurrence information exists waterquality function. Each is assigned awetland orderaccording for those sites, geographically extensive spatial data cover- the order of its associated stream. Lower order wetlands ages that are "complete" for these themes do not exist. It represent those that, theoretically, have the greatest potential should be noted that this methodology will, in most cases, impact on water quality while attenuating ninoff . Higher order direct initial selections for priority mitigation sites to areas that 1_0 y high-order wetlands order wetlands g g A for floodwater im order 4,5,6) 72 Q defined by mitigation [nd community t 1) e. Mh Identify all rive entify all contig Jary high-order mitigation sites wetlands defined by mitigation Determine wetland tes (protection or class and community type order based on enchancement kw@ g_-, stream order of restoration) wh adjacent stream. s Primary low-order wetlands p@ I for water quality ow-order wetla ds ement) defined by stream order 1,2,3) ion class and nity type Secondary low-oraer uous Identify all contig wetlands defined by mitigation wetland sites class and community type 11C '1757;JM Figure 2. Steps in water quality and floodwater storage analyses 12 Identifying Weiland NIfigatiofl Sites Using GIS are fairly remote and are least likely to have thorough Finally, it is recognized that surrounding land uses and preestablished rare/endangered species habitat and cultural management practices may pose a threat to the continued inventories. Thus, synoptic assessment of these impacts are viability of a mitigation site. Conversely, the negative impacts of deemed appropriate for this methodology only with subse- these activities could be ameliorated by a restored or enhanced quent site-specific inventory work. wetland. In this study, potential sources of threat are defined as nutrient, sediment, and toxicant sources and include domestic As previously mentioned, a Natural Areas Inventory of and industrial landfills, mines, and hazardous-waste sites. The the Edisto River basin was performed in 1992 in order to proximity of these potential sources to niitigation sites is graphi- identify natural areas of significance. The results of that cally represented on the final composite. Determining whether inventory indicate that natural habitat acreage - especially these sources would threaten the success of a mitigation project upland habitat - has dramatically decreased in the basin. In or, in fact, be mitigated by a restored wetland, would obviously fact, for the most part, river corridors serve as the last refuge have to be done on a site-by-site basis. The overlay does provide for natural plant communities. Thus, these identified com- an infori-nation tool that can assist in the indicated field work but munities as well as any upland significant natural areas are it cannot provide a substitute for the site-specific analysis. A overlaid on the composite to graphically display priority summary schematic of the GIS analyses as discussed in the above wetland mitigation sites in relation to these features. section is presented in Figure 3. 190010/ DevOlOPIn"t 13 Define protection sites Define enhancement Define restoration (intact NWI wetlands) by sites (all modified sites (PC wetlands) community type NWI wetlands) by community type Physical Suitability Analyses Natural Areas Inventory sites Upland forests Core wildlif (excluding pine habitat sites plantations) Analyset, Protected sites (State Parks National For@sts) Identify core/mitigation Identify all riverine complexes based on: potential mitigation sites 1) fragmentation based on: 2) interior habitat 1) stream order 3) size 2) hydrologic connectivity Optimal Wildlife Habitat Optimal Water Quality Optimal Flood Storage Mitigation Sites Mitigation Sites Mitigation Sites (large unfragmented (primary and secondary (primary and secondary complexes with adequate low-order wetland sites) high-order wetland sites) interior habitat) OR Determine endangered Determine sources of species, significant potential threat natural areas, cultural resource site occurrence Optimal Potential Mitigation Sites Based On: 0 Physical suitability 0 Wildlife habitat benefit I Water quality/floodflow storage contribution I Consideration of endangered species, natural areas, cultural resources site occurrence 0 Consideration of potential S w a@t@ sources of threat Figure 3. Summary of steps for identifying optimal sites 14 Identifying Wetland ffifigition Sites Using GIS Study Area The Four Hole Swamp sub-basin is one of four sub- basins in the Edisto River basin (Figure 4) in South Carolina and is the study area for this model application. In 1992, the South Carolina Water Resources Commission performed an ecological characterization of the Edisto River Basin. The purpose of the ecological characterization was to describe overall ecosystem health on the basis of land use/land cover trends, water quality trends, changes in hydrology, and Model biological indicators (Marshall, 1993). The following infor- mation about Four Hole Swamp sub-basin and the vicinity Application resulted from or was compiled during the characterization. The Four Hole Swamp headwaters originate in the Coastal Plain in Calhoun and Orangeburg Counties and drain about 650 square miles from four counties- Orangeburg, Calhoun, Dorchester, and Berkeley (Figure 5). The Four Hole Swamp system spans approximately 50 miles before it discharges into the mainstern of the Edisto River. The SCS has divided the state of South Carolina into six Land Resource Areas on the basis of soil conditions, climate, and land use (U.S. Department of Agriculture, 1978). These Land Resource Areas are defined primarily by soil characteristics that provide a basis for describing potential vegetation and land uses. The Four Hole Swamp sub-basin encompasses two of the six Land Resource Areas: the Atlantic Coast Flatwoods and the Southern Coastal Plain (Figure 6). The Atlantic Coast Flatwoods, which composes the vast majority of the study area, is nearly level and is dissected by many broad, shallow valleys with meandering stream channels. Elevations range from about 25 to 125 feet with local relief of a few feet to about 20 feet. The soils are predominantly somewhat poorly to very poorly drained and fonned in sandy to clayey Coastal Plain sediment. The Southern Coastal Plain is an area of gentle slopes. Local relief is in tens of feet. The soils are predominantly well or moderately well drained and formed in loamy or clayey Coastal Plain sediments. There are distinct patterns of land use and land cover IN "I'llow in the Four Hole Swamp sub-basin that correspond to the natural characteristics of the landscape (Figure 7). The fertile I% � I 'F loamy and clayey soils of the Southern Coastal Plain area support some of the most productive agricultural land in South Carolina. The sandy and clayey soils of the Atlantic 400 ry large agricultural . ...... Coast Flatwoods also support some ve - `.TWN11.1, 01, ,6N@o areas. As the watershed narrows at its base, however, the Flatwoods become dominated by forestland, primarily pine plantations. The riverine bottomlands or flood plains remain mostly forested, and they form a dendritic or branching pattern of forested wetland corridors throughout the sub- basin. Many of these wetlands are in a modified condition and have been ditched, drained, diked, or impounded. In many areas these wetlands have been totally altered, with the native vegetation converted to agriculture, pine plantations, Model APPlication 15 FOUR HOLE SWAMP SUB-BASIN Eg FOUR HOLE SWAMP LOCATION EDISTO RIVER BASIN ...... EDISTO RIVER SUB-BASINS 45 75 Figure 4. Location of Four Hole Swamp sub-basin 16 IdenfifYing Wetl8nd Afifigatlon Sites Using O/S FOUR HOLE SWAMP SUB-BASIN WITH COUNTIES F__1 FOUR HOLE SWAMP LOCATION COUNTY BOUNDARIES 15 Figure 5. Counties in Four Hole Swamp sub-basin MOM APPlic-7tiOn 17 SCS LAND RESOURCE AREAS Four Hole Swamp Sub-basin Four Hole Sub-basin LAND RESOURCE AREAS SOUTHERN COASTAL PLAIN ATLANTIC COAST FLATWOODS lo 1W -Figure 6. Land Resource Areas in Four Hole Swamp sub-basin 18 Identifying Wetland Mitigation Sites UsIng GIS 1989 LAND USE/LAND COVER TYPES Four Hole Swamp Sub-basin Four Hole Sub-basin it, LAND USE/LAND COVER TYPE ACRES PERCENT NON-FORESTED WETLANDS 8,856 2.20% FORESTED WETLANDS 78,069 19.40% UPLAND FORESTED/MIXED 60,370 15.00% F-1 UPLAND FORESTED/PLANTATION 72,511 18.02% OPEN WATER 1,902 .47% 1W -AGRICULTURE 167,109 41.53% A@ URBAN 13,607 3.38% FRANCIS BEIDLER FOREST Pik 2 4 lo .1- V Figure 7. Land use/land cover in Four Hole Swamp sub-basin Model ApplIcation 19 and, adjacent to Orangeburg, urban land uses. The city of The complexity issue required that the model be Orangeburg is the only large urban area within the sub-basin. implemented by using the GRID module in ARC/INFO. As a consequence, all data layers were converted to a grid cell The only protected natural area in the Four Hole fon-nat using the POLYGRID command. It was decided that Swamp sub-basin is the Francis Beidler Forest, an 11,000- a 16.4-foot (5-meter) cell size should be used to insure that acre bottomland hardwood swamp. It contains the largest even very small candidate mitigation sites were not general- old-growth stand of tupelo and cypress in the country, as well ized. This did not eliminate the map complexities - data as a large variety of birds, mammals, reptiles and amphibians, layers are 12,726 rows by 11,431 columns of grid cells - and many rare plants. The habitats of many plant and animal but permitted the data to be analyzed. The polygon identi- species in the sub-basin are threatened by hydrologic alter- fication numbers from ARC ('AU' value) are used for the cell ations and other manmade impacts. Several animal species values. The use of these values serves two purposes: that occur in the sub-basin, including the red-cockaded preserving the original polygon boundaries and providing a woodpecker, the bald eagle, and the wood stork, all of which tie to associated INFO attributes. The preservation of have specific habitat needs, are listed as federally endangered polygon boundaries was necessary for later analyses where or threatened. Numerous plants and animals listed as state wetland polygons were used as surrogates for elevation data. threatened or endangered are also found in Four Hole No digital elevation model or hypsography data were avail- Swamp. able for the study area. Additionally, the polygon identifica- tion number pen-nitted all original INFO data attributes to be used in subsequent GRID analyses. Attributes were added to Automating Criteria grid cell data by using the JOINITEM command. Data Preparation GIS Analyses The SCWRC has been building a natural resources GIs Initial Site Selection for the last five years. The Commission's efforts have been funded primarily through the support of NOAA and the state The initial phase of applying this model to the Four of South Carolina. Additional support has been received Hole Swamp sub-basin required defining mitigation classes. ffom USGS, USFWS, SCS, and the National Park Service. The three mitigation classes - restoration, enhancement, ARC/INFO GIs is used to implement this model .6 This GIs and protection - and the rationale for their selection criteria provides a full complement of various GIs functions, includ- are discussed in the previous section. Restoration sites were ing raster-based processing. selected by overlaying the hydric soils data layer with the uplands data layer, t1sing the CON function. The CON The hardware used was an IBM RISC/6000 technol- function provides data evaluation capabilities by using condi- ogy and includes a model 970 server and model 360 tional statements that test the presence or absence of workstation. The server is equipped with 12 gigabytes(GB) specified data values in individual grid cells. Each cell was of disc storage and 128 megabytes(MB) of memory (RAM). evaluated and only those areas containing both a hydric soil The workstation has 1 G13 of disc storage and 64 MB of and an agricultural land use were defined as potential RAM. These systems are connected by Ethernet. restoration sites. The original intent of implementing this model was to The protection and enhancement sites were selected use the ARC module with data in a traditional vector format. from the NWI data on the basis of their classification codes. It became apparent early on that this would not be possible Cells having a NVA code lacking a modifier (i.e. ditched or because of the complexity of the data. The Four Hole drained (d), diked or impounded (h), or excavated (x)) were Swamp sub-basin consists of portions of 17 quadrangles identified as protection sites. Conversely, those cells possess- containing over 402,000 acres. These individual quad- ing one of these codes were identified as enhancement sites. rangles were merged by dissolving their associated bound- Also, only those areas that apparently support hydrophytic aries, and then clipped to the hydro-unit boundary, creating vegetation, as indicated by the codes PEM, PSS, or PFO, large individual datafiles; for each data layer required by the were selected. study. This procedure created polygons that exceeded the All restoration, enhancement, and protection sites maximum number of arcs per polygon (i.e. 10,000 arcs per were combined to create a data file representing all potential polygon) permitted in ARC. The proximal analyses required mitigation sites in the Four Hole Swamp sub-basin. The by the model prevented the analyses being conducted on an individual quadrangle basis because it would introduce arbi- COMBINE function was used because all sites are indepen- trary polygon boundaries at the quadrangle boundaries. dent and mutually exclusive. Finally, any potential mitigation site contained within a protected area was eliminated since, theoretically, these areas are already protected and not a 6ARC/INFO is a proprietary software package developed and marketed viable mitigation alternative (Figure 8). The CON function is by the Environmental Systems Resource Institute, Redlands, California. used to test for the existence of a protected area. In this study case, the only protected area in the Four Hole Swamp is the 20 Idefitifying Wetland Mitigation Sites tlslflg GIS POTENTIAL MITIGATION SITES Four Hole Swamp Sub-Basin Four Hole Sub-Basin -44 & M; I Z_ 4W MITIGATION SITE TYPE ACRES 74,441 PROTECTION k ENHANCEMENT 9,166 RESTORATION 39181 0 FRANCIS BEIDLER FOREST Figure 8. Potential mitigation sites by mitigation class Model Applicatioft 21 Francis Beidler Forest, which is a private preserve managed In order to examine adjacency, the fragmented core by the National Audubon Society. Figure 8 shows that the habitat sites and the degraded mitigation sites are combined. overwhelming majority of potential mitigation sites within the The REGIONGROUP function in GRID, using the CROSS study area are protection sites. Four Hole Swamp has option, evaluates the connection of each cell in relation to its undergone much landscape alteration but still contains large surrounding or neighbor cell. All connected cells are given a areas of these quality wetlands. Several large enhancement unique identifier. In this particular case the command syntax sites, many of which appear as remnants of former Carolina appears as follows: Bays, exist and may provide significant mitigation opportu- nities. Few restoration sites exist in the study area. This scarcity does not seem problematic of the source data since these sites follow streams and are adjacent to "wetter" areas, as would be expected. Instead, the scarcity appears to be a function of the very restricted list of hydric soils used for the selection criteria. This will be discussed later. One apparent problem resulting from a delineation The above command specifies that each cell will be error was the misclassification of what is clearly a road evaluated in relation to its eight neighbors but will not be crossing the bottomland area. Although it should have been connected to any neighbor cell with a value of 0. Surrounding coded as transportation/utilities, this area was classified as cells with values other than 0 will be connected. Connecting agriculture in the Uplands data layer and thus was identified these degraded and core habitat sites results in regions with as a restoration site. It was not changed because doing so unique cell values. These grouped regions, or habitat would invalidate the field verification of source data. complexes, further define all potential wildlife habitat areas within the study area. Wildlife Habitat Opportunity Analysis The wildlife habitat opportunity analysis evaluated the Subsequently, each complex boundary is buffered potential mitigation sites with regard to their ability to serve inward by a distance of 3 28 feet (100 meters or 2 0 cells) using a wildlife habitat function. The first step in this analysis was the REDUCE function to eliminate all "edge" habitat (Figure the assembling of core habitat sites. These core habitat sites 11). The REDUCE function simply eliminates successive comprised all the protection sites selected above, all upland rows until the distance specified is met or the feature is forests (excluding pine plantation sites) from the uplands data eliminated. Thus, the reduction along the boundary elimi- layer, all protected areas (Francis Beidler Forest), and all nated all habitat complexes 656 feet (200 meters) or less in significant natural areas (Figure 9). On the basis of the model width- A comparison of Figure 10 and Figure 11 demon- definition, these sites represent prime wildlife habitat areas in stratesthis. By definition, areas within 328 feet (100 meters) the sub-basin. of a region boundary are "edge" habitat areas and not viewed as significant, since the fragmented nature of the study area The model defines multilane roads as significant barri- provides an abundance of this particular habitat. The habitat ers to wildlife movement. These multilane roads were complexes remaining represent areas containing adequate selected from the DLG roads data layer (codes 203 and 307). interior habitat for wildlife. The rei iaining regions were Since these codes represent only divided highways, South buffered outward to a distance of 3D feet (100 meters) - Carolina county highway maps were used to update other the original boundaries - using the EXPAND function. multi-lane roads. The selected roads were buffered to a distance of 131 feet (40 meters or 8 cells) to represent the The remaining habitat complexes were evaluated for highway right-of-ways, using the EXPAND function. This size characteristics. The model defines only habitat com- function adds successive rows of cells to a feature until plexes of 40 acres or greater as containing adequate space reaching the specified distance. All added cells are given for wildlife habitat. Given this criteria, each habitat complex values identical to the parent feature. No attempt was made was evaluated and only those containing a minimum of 40 to add new roads or to make a distinction between roads acres were selected using the CON function. The areas according to the number of lanes they might have. There- remaining after this procedure represent the optimal wildlife fore, all multilane roads were buffered the same distance. habitat complexes contained within the study area (Figure The buffered roads were overlaid with the original core 12). Finally, the original potential wetland mitigation sites, habitat sites, using the CON function. All cells containing a defined by mitigation class, were overlaid with the optimal core habitat site and a road were eliminated. habitat complexes, using the CON function. Only those cells containing both an optimal habitat complex and a potential Adjacent restoration and enhancement sites (termed here- mitigation site were selected. These represent the potential after as "degraded sites") are added to the fragmented core habitat mitigation sites meeting the wildlife opportunity analysis map to detern-Ane the amount of habitat each would add, upon criteria. mitigation, to the core habitat sites. The added sites were bisected with the same buffered roads used above (Figure 10). 22 IdentifYing Netl8nd AVIA98tion Sites Using GIS ALL CORE HABITAT SITES Four Hole Swamp Sub-basin Four Hole Sub-basin Ar M. r CORE HABITAT SITES Figure 9. Core habitat sites 90d0l APPlic8tiOfl 23 ALL CORE HABITAT AND DEGRADED SITES Four Hole Swamp Sub-basin Four Hole Sub-basin U. W _#d' ? fk CORE HABITAT SITES ENHANCEMENT SITES RESTORATION SITES MULTI-LANE ROADS o I lo Figure 10. Core habitat sites and adjacent degraded sites 24 IdenfifYing Wetland mlfivflon Sites UsIng 01S HABITAT EDGE ANALYSIS Four Hole Swamp Sub-basin Fo in f ALL HABITAT SITES WITH EDGE ELIMINATED Ak -.1 4( -Ara 2 Figure 11. Results of edge elimination analysis Model Applicati0fl 25 HABITAT SIZE ANALYSIS v Four Hole Swamp Sub-basin L Fou@ Hole Sub-basin L% -, -- UP P a L own op 6 db dr tj AV HABITAT SITES 40 ACRES OR GREATER T vd* Wf Ad Win 1. MILES Figure 12. All habitat sites 40 acres or greater in size 26 IdentifYing Wetland Mitig,flon s1tes Using ON POTENTIAL WILDLIFE SITES Four Hole Swamp Sub-basin Four Hole Sub-basin A. A bt P4@V MITIGATION SITE TYPE ACRES PROTECTION 50,286 ENHANCEMENT 4,081 N RESTORATION 776 FRANCIS BEIDLER FOREST 4 1 'd MILES Figure 13. All potential wildlife habitat sites Noolel Applicoftfl 27 Figure 13 depicts the potential mitigation sites that by polygonal boundaries, to be retrieved for each potential theoretically provide the greatest wildlife habitat benefit. Not mitigation site. surprisingly, a larger number of protection sites satisfy the wildlife opportunity criteria than do restoration or enhance- Initially, execution of the EUCDISTANCE function in ment sites. While several large enhancement sites were GRID was attempted to retrieve these IDs; however, this required identified as serving a wildlife habitat function, few of the massive amounts of temporary storage. The fi-inction exhausted restoration sites were considered optimal for wildlife habitat, 800 MB of free space on the disk and required more to complete owing to the restrictive size criteria. the task. As a result, an alternative method was devised. The buffered streams were overlaid with the potential mitigation sites. Water Quality and Floodwater Storage AD selected cells were given the original polygon ID value. The Analyses FREQUENCYcom-nandinARCwasusedtoehnmateduphcate These analyses considered the potential flood storage polygon IDs. An arbitrary value was assigned to each D and capacity a potential mitigation site might possess and the joined to the existing VAT data files using the JOINITEM ability of a site to contribute to stream water quality. Streams corrimand in ARC. The arbitrary value peraiitted the retrieval of and their associated drainage order were obtained from the all cells that defined the polygonal area of each adjacent potential DLG hydrography data layer. High-order streams were mitigation site. defined as all 4th-, 5th-, and 6th-order streams, while low- Figure 15 illustrates one problem with the definition of order streams were defined as 1st-, 2nd-, and 3rd-order primary high-order sites. While many adjacent sites were streams. All streams were selected and recoded to single accurately classified as primary high-order by this methodology, values reflecting either a high or low order. Figure 14 the mairistern of Four Hole contains numerous areas or islands represents all potential mitigation sites, and their stream wholly contained wifl-tin these primary high-order bottornland network, plotted by their respective order. Because of the wetlands. These wetlands were not identified as primary high- braided nature of portions of the Four Hole drainage system, order because they did not satisfy the distance criteria. Upon some portions of the high-order stream network had to be examination, most of these areas were found to be potential added. In these areas on the mainstem, the stream network mitigation sitesanddefinedasweflands; however, GRIDdoesnot disappears from the digital data. A single stream was digitized afford any easy means of selecting and recoding these areas in an to complete the drainage pattern. automated fashion. Potential flood storage sites (high-order sites) were AD other unselected potential mitigation sites were evalu defined as any potential mitigation site adjacent to a high- ated to determine if they were adjacent to a primary high-order order stream. Additionally, each site was defined as a site or to other secondary 1-ugh-order sites that were adjacent to primary and secondary site depending on its position on the primary high-order sites. The adjacency of sites was evaluated by landscape. In this study, wetland sites were used as a the REGIONGROUP function and according to the same surrogate for elevation data. If elevation data had been method used in the wildlife opporwnity analysis as described available, the landscape topography could have been defined above. Additionally, the CON function was used to differentiate and used to assess hydrologic flow. No elevation data exist between primary and secondary sites. in a digital format for the study area; thus, this model assumes that any adjacent site receives overbank flow from its related Figure 15 shows all identified primary and secondary high- stream or an adjacent wetland site. By definition, primary order sites. 'Me methodology was very successful in selecting sites are those potential sites immediately adjacent to a high- high-order sites - the bottorriland areas were identified as order stream and assumed to be most effective in stoning providing important flood control functions. However, the overbank flow. Secondary sites are adjacent to any primary inclusion of numerous secondary siteswithiri the bottorriland area site or adjacent to any secondary site that is adjacent to a was adeparture from the expected outcome of fl-lis methodology. primary site and assumed to be less important in floodflow A judgment was made to treat all high-order potential sites storage. identically regardless of their ranking (Le. primary or secondary). All high-order streams were buffered to a distance of Water quality sites, termed low-order sites, were defined as 32.8 feet (10 meters or 2 cells) using the EXPAND function. any potential mitigation sites adjacent to low-order streams. All This width was an arbitrary value selected to represent the selected sites were segregated into primary and secondary sites, stream surface, since the hydrography data layer is repre- using methods and selection criteria described above. Figure 16 sented by a single line in the data base. The assumption was shows all primary and secondary low-order sites identified by this that any potential mitigation site within 32.8 feet (10 meters) method. of a stream would receive overbank flow from the identified adjacent stream. This assumption requires each potential The model did not function well in the identification mitigation site within 32.8 feet (10 meters) of the stream to of low-order sites. Again, for purposes of this study, low- be retrieved with its associated polygon identification number order sites were defined as Ist-, 2nd- and 3rd-order sites and ("-ID") used to code the cell value in the original grid were assumed to represent headwater wetlands. As can be conversion of the data. The ED r-w-m-fits the entire area, as defined 28 IdenfifYing Wetland MV198fion SItes Using GIS POTENTIAL MITIGATION SITES AND STREAM NETWORK Four Hole Swamp Sub-basin Four Hole Sub-basin 'A C4 MITIGATION SITE TYPE PROTECTION ENHANCEMENT RESTORATION LOW ORDER STREAMS HIGH ORDER STREAMS FRANCIS BEIDLER FOREST 2 a lo ILES Figure 14. Potential mitigation sites and stream network Model Applicati0fl 29 HIGH ORDER HYDROLOGIC SITES Four Hole Swamp Sub-basin Four Hole Sub-basin HYDROLOGIC ORDER TYPES ACRES PRIMARY HIGH ORDER 30,470 SECONDARY HIGH ORDER 22,346 .0@` It- Figure 15. High-order potential wetland mitigation sites 30 IdentIfYing Wetland lyffig8fion Sites Using O/S LOW ORDER HYDROLOGIC SITES Four Hole Swamp Sub-basin Four Hole Sub-basin age A V IV ir HYDROLOGIC ORDER TYPES ACRES PRIMARY LOW ORDER 52,754 SECONDARY LOW ORDER 24,876 o 2 Figure 16. Low-order potential wetland mitigation sites Model ApplicatiOn 31 seen, however, it was often the case that many bottomland Model Complications/improvements sites were assigned a low-order as a result of this methodol- The wildlife habitat analysis was quite successful in ogy. Figure 14 reveals that this occurred because a large identifying potential mitigation sites that might serve as number of low-order streams flow directly into the mainstern optimal habitat according to model definitions. The water areas of the study area. quality/floodwater storage analyses were not as successful in Finally, all high- and low-order potential mitigation sites distinguishing between primary and secondary sites or in were combined to illustrate the relationship between the further identifying low- and high-order sites. high-order sites and low-order sites. Figure 17 depicts the Because elevation data were not available for the study combined sites and illustrates those areas that serve single or area, it was decided that wetlands data would be used as a dual hydrologic functions as defined by the model. The low- surrogate for characterizing the flood plain. An initial look at order stream assignment, described above, causes the major- the wetlands data revealed that, especially on the mainstem, ity of the wetlands in the study area to be identified as dual the only modifier that distinguished adjacent polygons was hydrologic function sites. the modifier relating to hydrologic regime. In large part, wetland "system," "class," and "subclass" were coded iden- Composite Overlay tically for adjacent polygons. Thus, it was originally theorized Figure 18 is a composite overlay of the opportunity that the hydrologic modifier incorporated into the NWI analyses depicting all selected wildlife, and high- and low- alphanumeric code (A,B,C,F,G, or H) might adequately order potential mitigation sites that meet any or all of the describe hydrologic properties within the riparian system. defined opportunity analyses criteria. Figure 18 illustrates For example, permanently flooded areas ("H") would have the importance of the mainstern area in the Four Hole greater connection to a water body than intermittently Swamp sub-basin. The area serves multiple opportunity exposed areas ("G") and so on. If this theory held true, sites functions in the sub-basin. adjacent to a stream as defined in the DLGs (i.e. primary sites) would be distinguished from areas farther from the stream Figure 19 shows the same identified opportunity sites (i.e. secondary sites) as denoted by different hydrologic shown in Figure 18 broken out by mitigation class. A modifiers (e.g., F vs. C) in the data base. Upon testing this comparison of Figures 8 and 19 shows that the sites theory in the procedures described above, it became appar- eliminated by this methodology are those very small isolated ent that, due to the complexity of the hydrologic system in candidate sites that exist in the study area. Four Hole Swamp, these relationships do not necessarily hold true. Figure 22 shows the highly complex hydrologic Unique OpportunitylPotential Threats nature of the wetland system especially as it occurs on the Analysis mainstem. The braided stream network pattern, which in The potential mitigation sites identified in the overlay some parts of the data base was digitized as a single line, composite were evaluated with respect to the unique oppor- further prevents a clear characterization of the riparian tunities existing in the sub-basin. Unique opportunities were system according to this methodology. defined as the occurrence of sensitive species or communities of concern, archaeology sites, significant natural areas, or The second problem encountered in this methodology historic sites. These sites, in combination with the identified was the identification of wetlands on the basis of stream order sites, present unique opportunities for mutual protection of of the adjacent stream. As mentioned, many of the wetland important sub-basin resources. The identified unique sites areas associated with the mainstern of Four Hole Swamp are overlaid with the potential mitigation sites to determine were actually identified as having low-order wetland proper- the number and type of unique opportunities failing within ties. While many of these wetlands serve the dual hydrology each site (Figure 20). Each site is labelled with its related function identified in this study, it can be argued that, unique opportunities for future reference. according to the assumptions and definitions provided by this model, these areas are critical for floodflow storage. A Lastly, identified mitigation sites are evaluated with reevaluation of stream order definition could possibly contrib- respect to the potential threats existing in the sub-basin. ute to a clearer distinction between the two wetland types. Potential sources of threats were defined as hazardous- waste For example, had low-order streams been defined as only 1 st- sites (including generating, disposal, treatment, or storage and 2nd-order, perhaps fewer low-order wetlands would sites), mining sites, and industrial and domestic waste sites. have been identified on the mainstem. Figure 21 shows the potential threats in the sub-basin in relation to the identified sites. 32 Identifying Netland Nitigation Sites Using GIS POTENTIAL HYDROLOGIC SITES Four Hole Swamp Sub-basin Four Hole Sub-basin %fir, Old HYDROLOGIC ORDER ACRES LOW ORDER 24,908 HIGH ORDER 93 LOW AND HIGH ORDER 49,410 FRANCIS BEIDLER FOREST 1. MILES Figure 17. All potential wetland mitigation sites identified by water quality/floodwater storage analyses ff0d01 AAPlicatiOn 33 ALL OPPORTUNITY ANALYSES SITES Four Hole Swamp Sub-basin Four Hole Sub-basin ik 4 dk OPPORTUNITY ANALYSES CATEGORIES ACRES LOW ORDER 13,286 HIGH ORDER 45 LOW AND HIGH ORDER 9,632 rr. POTENTIAL HABITAT 3,695 POTENTIAL HABITAT AND LOW ORDER 11,621 POTENTIAL HABITAT AND HIGH ORDER 48 POTENTIAL HABITAT AND LOW AND HIGH ORDER 39,778 FRANCIS BEIDLER FOREST o I I Figure 18. Composite overlay of potential wetiand mitigation sites identified by all opportunity analyses 34 IdenfifYing Wetland NIV98fidn s1tes t/s/flg O/S FINAL SELECTED MITIGATION SITES Four Hole Swamp Sub-basin Fow Hole Sub-basin 1k is (k. t jA MITIGATION SITE TYPE ACRES PROTECTION 67,733 ENHANCEMENT 7,427 RESTORATION 2,946 FRANCIS BEIDLER FOREST W..;5 G 1 4 lo "LES Figure 19. Final selected potential mitigation sites identified by mitigation class Model ApplicatlOn 35 UNIQUE OPPORTUNITY SITES Four Hole Swamp Sub-Basin Fou@ Hole Sub-Basin fA 'A W -Owl- UNIQUE OPPORTUNITY SITES SENSITIVE SPECIES SITE ARCHEOLOGICAL SITE HISTORIC SITE SIGNIFICANT NATURAL AREA MITIGATION SITE TYPE PROTECTION ENHANCEMENT RESTORATION FRANCIS BEIDLER FOREST o 8 1@ Figure 20. Unique opportunity occurrence 36 Identlfylflg Wetland 91figstlon Sltes Using GIS POTENTIAL THREAT SITES Four Hole Swamp Sub-basin Four Hole Sub-basin Y44" POTENTIAL THREAT SITES A .0 MINING SITE HAZARDOUS WASTE SITE It LANDFILL SITE MITIGATION SITE TYPE PROTECTION ENHANCEMENT RESTORATION FRANCIS BEIDLER FOREST lo MILES Figure 21. Potential threat occurrence Model Application 37 NWI FLOOD REGIME CATEGORIES Four Hole Swamp Sub-Basin A- Four Hole Sub-Basin 41 1101 NWI FLOOD REGIME CATEGORIES A -TEMPORARILY FLOODED B-SATURATED C - SEASONALLY FLOODED D - SEASONALLY FLOODED/WELL DRAINED E - SEASONALLY FLOODED/SATURATED F - SEMIPERMANENTLY FLOODED G - INTERMITTENTLY EXPOSED H - PERMANENTLY FLOODED Figure 22. Hydrologic regime of potential mitigation sites in Four Hole Swamp 38 10"entIfY1179 Wetland 91fig,7tion 51tes Using O/S Field-Truthing Verification of Source Data The results of the field work done as part of this study After identifying potential mitigation sites through the indicated that the thematic data used in applying this meth- GIS analyses, a sample set was extracted for field sampling. odology are accurate with some exceptions. Acreages The objective of the field visits was to generally validate the derived from the NWI data appeared to be, for the most part, assumptions made for identifying the three mitigation classes accurate, although precise boundaries were not delineated in as described earlier in this study. This was accomplished by the field. Acreage figures derived during field verification 1) verifying the accuracy of the GIS-generated and source were estimates. data regarding community type or land use, approximate size, presence of alteration (if indicated by the NWI modifiers); General community types, with few exceptions, were and 2) generally assessing the logic used in defining mitiga- also accurate; however, in several instances, especially in the tion classes. It should be noted that because of resource headwater bottoms, large tracts have been recently clearcut. constraints the rigorous sampling of species type, species Thus, these areas obviously do not presently support the composition, and soil types was not performed. Rather, community types indicated in the NWI data derived from qualitative assessments of these factors were made. In 1989 photography. The implication for mitigation in these addition, a qualitative assessment of the site's wetland status instances is not clear. It could be argued that, depending on was made. Such characteristics as wetland plant species and the hydric status of species pioneering the clearcut sites, these various soil properties indicative of "driving" hydrology were areas could potentially serve as enhancement sites, with the generally assessed to confirm that the site would likely qualify planting of bottomland species being indicated (personal as jurisdictional or could be brought into jurisdictional status communication, Kent Campbell, United Consulting Group, upon mitigation. Precise delineations, which would ulti- Ltd.). mately determine the status of selected polygons, were not within the purview of this study. It should be noted that the Some exceptions to the NWI-based classification of assumptions made to define the opportunity criteria outlined palustrine emergent areas were noted. Many of these areas in this study were not verified in the field - i.e. site-specific are actually young pine plantations and, in some cases, field evaluations were not made to determine the ability of a agricultural fields. It is thought that environmental conditions wetland site to serve a wildlife habitat, water quality, or at the time of image capture might have contributed to the hydrology function. Rather, the rationale used to develop the misinterpretation of these communities. South Carolina criteria used for these analyses is supported by the literature, experienced above-average precipitation in 1989, the year as described earlier in this study. during which the photography was taken. Also, the image was captured in early spring, a wet time of year. Thus, some In sampling the sites for field verification, several factors areas interpreted as emergent wetlands were probably ponded were considered. It was desired that statistical rigor be used agricultural fields or pine plantations. Finally, the immature in site selection - that is, that a proportionate number of status of the pine species at the time of image capture and the potential mitigation sites be randomly selected for each short stature of agriculture crops contributed to the mitigation class (enhancement, restoration, and protection). misclassification. of an emergent, persistent community type However, because of limited resources and time, it was for these polygons. necessary that sites be relatively accessible. While it is recognized that the identification of sites on the basis of their For the most part, it was possible to locate restoration accessibility, rather than a random sample, would result in a sites, or PC wetlands, on the ground; however, this mitiga- biased sampling of sites, the reality of resource constraints tion class was more difficult to assess (i.e. to verify on the basis dictated that those sites most accessible be identified and field- of the two factors defining this class - agricultural land use and truthed. a specific soil type) since detailed soil surveys were not made in the indicated areas. The final composite overlay of potential mitigation sites (defined by the three mitigation classes) was visually analyzed Without exception, it was found that NWI polygons to identify clusters of sites, representative of the three coded with a modifier indicative of ditching, impoundment, mitigation classes, that might serve as potential field-truthing or excavation had, in fact, been modified accordingly. sites. Roads providing access to these field sites were Unfortunately, the converse was not always true. It was identified by overlaying the primary and secondary road data sometimes the case that a site, although listed as a protection layer. Quad maps were then cross referenced to identify site because of the lack of a modifier in the NWI data base, roads, other than primary and secondary roads, that might had experienced some degree of ditching or was otherwise yield access to the field sites. An attempt was made to locate modified. This condition was especially apparent in the case both isolated (Figure 23) and riverine (Figure 24) clusters of side ditching and, in some instances, where the main throughout the length of the basin. channel had been straightened or excavated to enhance NOdOl APPlic8tiOn 39 FIELD CHECK MAP WADBOO SWAMP QUADRANGLE 'HECK P- -A MITIGATION - COMMUNITY TYPES PROTECTION -EMERGENT PROTECTION - WET FLATWOOD/SAVANNAH PROTECTION - BAY FOREST/SHRUB BOG PROTECTION - BOTTOMLAND/SWAMP ENHANCEMENT-EMERGENT ENHANCEMENT - WET FLATWOOD/SAVANNAH ENHANCEMENT - BAY FORESTSHRUB BOG ENHANCEMENT - BOTFOMLAND/SWAMP RESTORATION SENSITIVE SPECIES SITE ARCHAEOLOGICAL SITE El HISTORICAL SITE MINING SITE HAZARDOUS WASTE SITE LANDFILL SITE PRIMARY OR SECONDARY ROAD VPES Figure 23. Isolated field check site 40 IdeftfifyIng Wetland ffifigotlon Sites Using GIS FIELD CHECK MAP HARLEYVILLE QUADRANGLE -CK Pi,,, r -- MITIGATION - COMMUNITY TYPES PROTECTION - EMERGENT PROTECTION - WET FLATWOOD/SAVANNAH PROTECTION - BAY FOREST/SHRUB BOG PROTECTION - BOTTOMLAND/SWAMP ENHANCEMENT-EMERGENT ENHANCEMENT - WET FLATWOOD/SAVANNAH ENHANCEMENT - BAY FOREST/SHRUB BOG ENHANCEMENT - BOTTOMLAND/SWAMP RESTORATION SENSITIVE SPECIES SITE ARCHAEOLOGICAL SITE HISTORICAL SITE MINING SITE HAZARDOUS WASTE SITE LANDFILL SITE PRIMARY OR SECONDARY ROAD Figure 24. Riverine field check site Model ApplicatiOly 41 drainage of the surrounding landscape. On the basis of the farmed, while others were fallow or planted in wildlife food noted exceptions between data and field checks, it can be plots. Again, this mitigation class was the most difficult to reasonably inferred that the number of potential enhance- assess because detailed soil surveys were not made. It was ment sites in the Four Hole sub-basin is greater than the noted, however, that in many cases these areas provided number found through application of this methodology. contiguity for fragmented riverine systems, especially in headwater areas. It was also observed that abandoned Other Observations agricultural fields, not identified by this methodology, were a An effort was also made to generally assess the wetland common feature of the landscape, occurring both in associa- status of the selected mitigation field sites. Ailthough identi- tion with wetland systems and in upland areas. It became fied NWI polygons, both modified (enhancement sites) and apparent that the criteria used in this methodology to locate unmodified (protection sites), generally supported a wetland potential wetland restoration sites were not adequate for community and were delineated as such during image identifying all prior converted wetlands or farmed wetlands interpretation, it was sometimes the case where "driving" that have since been abandoned. As mentioned previously, hydrology did not appear to be present "on the ground" as the soils used to define hydric agriculture fields were those indicated by non-hydric soil conditions or the invasion of identified by soil scientists as the least productive because of plant species requiring more xeric habitat conditions. This their extreme hydric condition. However, complex eco- "drying out" of certain areas, especially those areas indicated nomic factors and environmental factors other than soil in the NWI data as temporarily flooded, could be attributed productivity are also responsible for the abandonment of to one or a combination of several factors, as follows: farming operations. Thus, additional data and/or an amended methodology would be required for a thorough identification � The ditching and subsequent drainage of many of all PC wetlands in this watershed. modified wetland areas to the point where Finally, the alphanumeric NWI code provides some water tables are significantly lowered. subtle clues about specific land use activity that, if properly � The possibility that South Carolina is at the end interpreted, might allow for the identification of polygons of a 15-year drought cycle. having a greater desirability for mitigation. For example, while many palustrine, unconsolidated bottom areas (coded � Increased water withdrawals over the past as "PUB" in the NWI data base) were actually reservoirs decades. lacking mitigation potential, sites exist that qualify as prime areas for mitigation, depending on the degree of soil distur- If, in fact, ditching is responsible for the drying out of bance and other physical factors. It has been suggested that some wetland areas, it becomes obvious that hydrologic some palustrine, unconsolidated bottom areas that have restoration might reverse the observed trend. While there been excavated actually represent gravel pits, abandoned or has been some fear expressed by the farming community that otherwise, and possess potential for vegetation reestablish- such activity might reverse draining so that productive ment (personal communication, Charlie Storrs, U.S. Fish farmlands again become flooded, successful agricultural and Wildlife Service). These areas were not identified by this water table management has occurred in the Coastal Plain of methodology, since only sites currently supporting vegeta- North Carolina. In these circumstances, it has been possible tion were selected. Other mitigation sites identified through for fanners to regulate water table levels to optimize water this methodology, but that might be given more detailed availability for crop growth. At the same time, the contrib- attention during the physical suitability analyses, were veg- uting watershed receives the ecological benefit of restored etated areas that have been excavated. In many cases, these hydrology and, subsequently, wetland maintenance (per- areas have been manipulated and then abandoned, as sonal communication, Bud Badr, SCWRQ. indicated by the establishment of vegetation. Again, depend- ing on the composition of species pioneering these sites, they It was also observed in the field that PC wetlands, as may or may not be desirable for mitigation. defined and identified in this study, varied in their ability to support agricultural crops. Some appeared to be actively 42 IdentIfYing Wetland lIfffigatlon SItes Using G/S The methodology described in this report identifies potential wetland mitigation sites on the basis of physical factors (soils, hydrology, vegetation) and according to the following characteristics indicative of ecological function: � Fragmentation. � Contiguity with other wetland areas and, thus, inclusion in large complexes. 0 Existence of interior habitat for wildlife. � Juxtaposition to water bodies and thus the opportunity to provide floodflow storage and water quality Conclusions improvement. � The existence of potential threats to the ecological integrity of a site. � Opportunities to provide habitat for rare, threatened, or endangered species and communities. The value of considering these ecological factors in mitigation site selection, for banking or otherwise, cannot be overstated. Indeed, fragmentation continues to persist as a result of wetland fill activity. Thus, large complexes of wetland sites - areas vital to the ecological integrity of watersheds - are dwindling. Strategic reconstruction of indicated mitigation sites could restore or improve the ecological health of many watersheds across the country. The physical suitability analyses were successful in thoroughly inventorying the landscape for potential protec- tion and enhancement sites according to their respective definitions, although wetlands other that those delineated by NWI were not identified. It was noted in the field, however, that abandoned farmed wetlands and prior converted wet- lands were common throughout the study area although not always selected by this methodology as potential restoration sites. It is felt that this is partially attributable to the rather conservative selection of hydric soils in the overlay operation. If the entire list of hydric soils had been used for each county rather than the few identified in this study as extremely hydric, it is probable that this methodology would have identified a greater number of the abandoned farmed wetland and prior converted sites existing in Four Hole Swamp sub-basin. TY However, the factors contributing to the wholesale abandon- ment of farming operations in the Coastal Plain and in other places are largely a function of complex economic conditions and only partially related to the physical characteristics of the soil. Data on farmland abandonment are available in hard copy from SCS. It is feasible that these data, in digital forrn or otherwise, could be used to supplement the results obtained from these GIS analyses in identifying PC wetlands. Results from this study also indicate that although the model was successful in identifying enhancement sites - C017clusiOns 43 many of which appear to have true mitigation potential as clear delineation of primary and secondary sites was not they are currently being effectively drained - there are always possible. This component of the methodology could actually a greater number of potential enhancement sites in not consider the complex hydrology existing in the Four Hole the field than determined by this methodology. This is due Swamp drainage system. Elevation data would be required to the fact that a large number of sites identified as protection to better characterize hydrologic conditions in the riparian sites have actually been modified in some way. While the data system. used for application of this methodology were fairly current, it is recognized that cross-referencing the final sites selected As would be expected, the results of the opportunity through this methodology with NAPP or other aerial photog- analyses indicate that the mainstern of Four Hole Swamp is raphy, prior to field verification, would expedite the site an area that contributes greatly to the ecological integrity of selection process. Interpretation of current aerial photogra- the sub-basin. The mitigation and annexation of degraded phy can detect recent changes in land use or land cover as well wetland sites to intact and protected portions of this riparian as verify the alphanumeric code provided by the National system, could ensure the long-term ecological viability of Four Wetlands Inventory data. Hole Swamp. Execution of the wildlife habitat component resulted in While the information resulting from this methodology successful identification of potential mitigation sites that can better direct mitigation decisions made by those in the might serve as optimal habitat according to model definitions. regulatory arena, there is of course no substitute for the Many of the restoration sites fell out of the model; however, expertise contributed by knowledgeable specialists. This large complexes of the three mitigation classes, all which methodology is intended to be a decision support tool, not possess adequate interior habitat, were found. Execution of a decision system. It considers landscape level indicators of the water quality/floodwater storage analyses was not com- function and places priority on contiguous complexes of pletely successful in identifying distinct low- and high-order potential mitigation sites. By explicitly stating ecological wetland sites. While high-order wetlands were consistently assumptions that should be considered when selecting sites identified along the mainstern, low-order wetlands were for wetland mitigation, it can help streamline the decision- identified in the headwaters as well as on the mainstern. A making process through an initial identification of potential different characterization of wetland orders, would likely mitigation sites requiring further site-specific evaluation by contribute to better definition of these areas. In addition, a wetland specialists. 44 Ident1frIng wetland Ofig8fion SlIes I/Sing GIS Adamus, Paul R. 1987. Wetland Evaluation Tech- nique for Bottomland Hardwood Functions. EPA document. Anderson, J.A., E.E. Hardy, J.T. Roach, and R.T. Witmer. 1976. A land use and land cover classification system for use with remote sensor data. U.S. Geological Survey Professional Paper 964. Asldns, R.A., M.J. Philbrick, and D.S. Sugeno. 1987. Relationship between the regional abundance of forest and the composition of forest bird communities. Biol. Conserv. 39: 129-152. Brinson, M.M. 1988. Strategies for assessing the Ref erences cumulative effects of wetland alteration on waterquality. Environmental Management 12(5):655-662. Cowardin, L.M., V. Car-ter, F.C. Golet, and E.T. LaRoe. 1979. Classification of wetlands and deepwater habitats of the United States. U.S. Fish and Wildlife Service, FWS/OBS-79/31, Washington, D.C., 103 pp. Diamond, J. M. 1976. Island biogeography and conservation: strategyand limitations. Science 193:1027- 1029. Environmental Law Institute. 1993. WetlandMitiga- tion Banking. Environmental Protection Agency. 1993. Draft Mitigation Banking Guidance, Region IV, Atlanta, GA. Forman, Richard T. T., and Michael Godron. 1981. Patches and Structural Components for a Landscape Ecology. Bioscience. (31)10:733-740, Gosselink, J.G., B.A. Touchet, J. VanBeek, and D. B. Hamilton. 1990. Bottomland Hardwood Forest Ecosys- tem Hydrology and the influence of Human Activities: the Report of the Hydrology Workgroup. Pages 347 - 387 in J. G. Gosselink, L.C. Lee, T.A. Muir (editors). Ecological Processes and Cumulative Impacts Illustrated by Bottomland Hardwood Wetland Ecosystems. Lewis Publishers, Inc. Hale, A.M., W.D. Marshall, and J.D. Scurry. 1991. GIS Plus Policy Research: South Carolina's Natural Resources Decision Support System. Geo Info Systems. (1)6:22-35. Harris, L.D., L.D. White, J.E. Johnston and D.G. Milchunas. 1974. Impact of Forest Plantations on North Florida Wildlife and Habitat. Proceedings of the 28th Annual Southeastern Association of Game and Fish Com- mission 28:659-657. Harris, L.D. 1984. The fragmented forest: Island Biogeography Theory and the Preservation of Biotic Diversity. University of Chicago Press, Chicago, 211 pp. 45 Harris, L.D. 1985. Conservation corridors: a Noss, R.F. 1983. A regional landscape approach to highway system for wildlife. ENFOReport85-5. Environ- maintain diversity. BioScience 33:700-706. mental Information Center of the Florida Conservation Foundation, Winter Park, Florida. Nutter, W.L. and J.W. Gaskin. 1989. Role of Stream- side Management Zones in Controlling Discharges to Harris, L.D. and James Gosselink. 1990. Cumulative Wetlands. Pages 81-84 in D.D. Hook and R. Lea (editors) Impacts of Bottom land Hardwood Forest Conversion on Proceedings of the symposium: Forested wetlands of the Hydrology, WaterQuality, and Terrestrial Wildlife. Pages Southern United States. U.S. Department of Agriculture, 259 - 322 in J. G. Gosselink, L.C. Lee, T.A. Muir (editors). Forest Service. Gen. Tech. Rep. SE-50, Asheville, N.C. Ecological Processes and Cumulative Impacts Illustrated by Bottomland Hardwood Wetland Ecosystems. Lewis Publish- O'Neil, L.J., T. M. Pullen, Jr., R.L. Schroeder. 1991. ers, Inc. A Wildlife Community Habitat Evaluation Model for Bottom land Hardwood Forests in theSoutheastern United Karr, J.R. and I.J. Schlosser. 1978. Water resources States. U.S. Fish and Wildlife Service Biological Report and the land-water interface. Science 201: 229-234. 91N. Kuenzler, E.J. 1989. Value of Forested Wetlands as Peterjohn, W.T., and D.L. Correll. 1984. Nutrient Filters for Sediments and Nutrients. Pages 85-96 in D.D. Dynamics in an Agricultural Watershed: Observations on Hook and R. Lea (editors). Proceedings of the Symposium: the Role of a Riparian Forest. Ecology 6(5):1466-1475. Forested Wetlands of the Southern United States. U.S. Department of Agriculture, Forest Service. Gen. Tech. Rep. Preston, Eric M. and Barbara L. Bedford. 1988. SE-50, Asheville, NC. Evaluating Cumulative Effects on Wetland Functions: A Conceptual Overview and Generic Framework. Environ- Langley, Albert K. Jr., and Donald J. Shure, 1980. mental Management 12(5):565-583. The Effects of Loblolly Pine Plantations on Small'Mam- mal Populations. American Midland Naturalist 103(l):59- Saunders, Denis A., Richard J. Hobbs, and Chris R. 65. Margules. 1991. Biological Consequences of Ecosystem Fragmentation: AReview. Conservation Biology 5:18-32. Lee, Lyndon C, and James G. Gosselink. 1988. Cumulative Impacts on Wetlands: Linking Scientific Scott, M.L., B.A. Neiss, W.H. Patrich, and C.A. Assessments and Regulatory Alternatives. Environmental Segelquist. 1990. The Effect of Development Activities Management 12(5):591-602. on Water Quality Functions of Bottomiand Hardwood ecosystems: the Report of the Water Quality Workgroup. Leibowitz, S. G., B. Abbruzzese, P. R. Adamus, L. E. Pages 411 - 453 in J. G. Gosselink, L.C. Lee, T.A. Muir Hughes, J. T. Irish. 1992. A Synoptic Approach to (editors). Ecological Processes and Cumulative Impacts Cumulative Impact Assessment, EPA/600/R-92/167, Illustrated by Bottomland Hardwood Wetland Ecosystems. October 1992. Lewis Publishers, Inc. Lowrance, Richard, Ralph Leonard and Joseph Strahler, A.N. Hypsometric (area-altitude) analysis Sheridan. Managing riparian ecosystems to control of erosional topography. Geological Society of America, nonpoint pollution. Journal of Soil and Water Conserva- Bulletin 63: 1117 - 1142. tion. Feb.-Mar. 1985:87-91. Taylor, J.R., M.A. Cardamone and W.J. Mitsch. Marshall, W.D. 1993. Assessing Change in the Edisto 1990. Bottom land Hardwood Forests: TheirFunctions RiverBasin: an Ecological Characterization. Report#177. andValues. Pages 13- 86inJ. G. Gosselink, L.C. Lee, T.A. SCWRC. Muir (editors). Ecological Processes and Cumulative Impacts Illustrated by Bottornland Hardwood Wetland Ecosystems. Mitigation Site Type Classification: A Methodology to Lewis Publishers, Inc. Classify Pre-Project Mitigation Sites and Develop Perfor- mance Standards for Construction and Restoration of For- Temple, S.A. 1986. Predicting impacts of habitat ested Wetlands. Results of an EPA-Sponsored Workshop, fragmentation on forest birds: A comparison of two models. Falls Creek State Resort Park. Pikeville, TN, August 13-15, Pages 301 - 304 in J. Verner, M. L. Morrison, and C.J. 1989. Ralph, eds. Wildlife 2000: Modeling habitat relationships of terrestrial vertebrates. Univ. Wisconsin Press, Madison. Noble, Robert E., and Robert B. Hamilton. 1975.Bird Populations in Even-Aged Loblolly Pine Forests of South- U. S. Department of Agriculture. 1978. General soil eastern Louisiana. Proceedings of the 29th Annual South- map of South Carolina. USDA Soil Conservation Service. eastern Association of Game and Fish Commission 29:441- 450. 46 10eflfifYing Wethind AfM98flon Sites 11SIng G/S Whigham, D.F., C. Chitterling and B. Palmer. 1988. Impacts of Freshwater Wetlands on Water Quality: A Landscape Perspective. Environmental Management 12(5):663-671. White, J. and C. Aulbach-Smith. 1993. Edisto River Basin Natural Area Inventory: Survey Standards and Guidelines. Report for the Natural Resources Decision Support System prepared by The Nature Conservancy, Chapel Hill, North Carolina, and by the South Carolina Water Resources Commission, Columbia, South Carolina. May 1993 edition. 110p. White House Office of Environmental Policy. 1993. Clinton Administration Proposal on Protection of U.S. Wetlands. World Wildlife Fund. 1992. Statewide Wetlands Strategies. A Guide to Protecting and Managing the Resource. Island Press, Washington, D.C., 268 pp. ReferencOs 47 Appendices Appendix I Generalized NWI Wetlands Used in Amalyses* Emergent (Savannahs, Wet Meadows, Freshwater Marsh) PEM1A PEMY PEM1N PEM1B PEM1H PEM1R PEM1C PEM1K PEM1T PEMA PEMlMh PEMFx PEMC PEM1P PEM/SS1T U/PEM1T Wet Flatwoods and Pine Savannah PF04A PF04/SS3A - PSS4C PF04C PF04/SS3C PFOSS4A PF04R PF07A PSS3A- PF04S PF07S PF04/1A PSS4A Bottomland Hardwoods, Wooded Swamps, Decidu- ous Shrub Swamps PFOIA PF01B PSS1C PF01S PFOIC_ PSS1F_ PF01/2A PFOIF- PSS1N PF01/3A PF01G- PSS1R PF01/4A_ PF01P PSS1T PF01/4S PF01R- PSS2KH PFOl/SS3A- PF01T PSS6C PFOI/SS4A- PF01/2- PSS6F - PF01/4C PF01/3C PSS6K - PF01/4R PFOI/3R PSS6M PFOl/SS4R PFO1/SS3C PSS6N PF04/1C PFO1/SS3F PSS6R- PF04/1R PFO1/SS3R PSS1/2F- PFO/SSIC PF02 PSS1/2T PSS1A PF05 PSS1/3C Pssis PF06C - PSS1/3F - PSS1/3A- PF06F - PSS1/3H PSS1/3S PF06G- PSS1/3R PSS1/4A PF06N PSS1/3T PSS1/4C PF06/AB4Hh PSS1/4T PSS3/1A PFO/EMIC PSS1/7R PSS6Ad PFO/EM1F PSSC PSS6S PFO/SS6Fh PSS6/EMIF PFO/SS6T PSS/EMlC John Hefner, Fish and Wildlife Service, National Wetlands Inventory AppefldiCOS49 Bay Forests, Evergreen Shrub Bogs Appendix N PF01/3B PSS1B - PF01/413 PSS3A Hychic Soils List by County Used PF01/SSB, PSS3B- for Analyses* PF03/SS1B PSS3C- PF04B PSS3R- PF04/IB PSS3S Berkeley PF04/3C PSS7A- Meggett loam PF04/2C PSS7B Pamlico mucl@ PF04/SS1B PSS7C Pickney loamy fine sand PF04/SS3B PSS7F PF07B PSS7R PF07C PSS1/3B Calhoun PF07Kh PSSIAB Swamp PF07R - PSS3/1A PFO/SS3B PSS3/1B Dorchester PSS3/1C Elloree loamy fine sand Grifton fine sandy loam Mouzon fine sandy loam Osier loamy fine sand Appendix Rutlege loamy fine sand Generaked Land Use Data Used in Orangeburg Analyses Bibb sandy loam Elloree loamy sand Urban Johnston sandy loam U11 Mouzon fine sandy loam U12 U13 U14 U15 -@'Dennis De Francesco, Soil Conservation Service U16 U17 Agricultural Cropland/Pastureland U21 Mixed Forest U41 U42 U43 Pine Plantation U42P Other Upland U22 U31 U32 U75 U76 50 IdentifYing WetlOflar NItig-1ti" Sit" Ils'ng G/S Z-- Toward No Net Loss Total copies: 300 Total cost: $4840.50 Cost per copy: 16.15 Date: 11-93 S.C. Water Resources Commission Printed on recycled paper - 3 6668 00003 8259