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                                                                                                   A Summary Review
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                                                                                                   Alan Desbonnet
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                                                                                                   Pamela Pogue
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                                                                                                   Virginia Lee
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      This publication was funded by the NOAA Office of Sea Grant,
      U.S. Department of Commerce, under Grant #NA 89 AA-D-SG-
      082, and by NOAA Office of Coastal and Ocean Resource
      Management, under Grant #NA90 AAH C2433. The U.S.
      Government is authorized to produce and distribute reprints for
      governmental purposes notwithstanding any copyright notation
      that may appear hereon.


      Additional copies of this publication are available from Rhode
      Island Sea Grant Publications, University of Rhode Island Bay
      Campus, Narragansett, RI 02882-1197. Order P 1333.

      National Sea Grant Depository Publication #RIU-T-93-001. Loan
      copies available from the National Sea Grant Depository, Pell
      Library Building, University of Rhode Island Bay Campus,
      Narragansett, RI 02882-1197.


      Sea Grant is a national pi-ogram dedicated to pi-oinoting the wise
      use and development of marine resourcesJor the public henefill.


      This document should be referenced as:
      Desbonnet, A., P. Pogue, V. Lee and N. Wolff. 1994. Vegetated
      Buffiei-s in the Coastal Zone-A SuminarY Review and Bihliogra-
      ph@v. Coastal Resources Center Technical Report No. 2064.
      University of Rhode Island Graduate School ofOceanography.
      Narragansett, RI 02882. 72 pp.































      ISBN 0-938 412-37-x





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                                                                                 J%A        V L    0 tj
                                                                                        `7


             Vegetated Buffers
             in the Coastal Zone

             A Summary Review
             and Bibliography






             Alan Desbonnet
             Pamela Pogue
             Virginia Lee
             Nicholas Wolff













             Coastal Resources Center
             Rhode Island Sea Grant
             University of Rhode Island

             July 1994

             ISBN 0-938 412-37-x







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                   CHAS. SC 29408-2623







          Acknowledgments

              We are grateful to the many people who provided material and insights for
          this manuscript: Dr. Art Gold - Department of Natural Resource Science, Univer-
          sity of Rhode Island; Grover Fugate, Dave Reiss, Mark Imperial, Jeff Willis, and
          Jim Boyd - Rhode Island Coastal Resources Management Council; Scott'Millar -
          Rhode Island Department of Environmental Management. We also gratefully
          acknowledge the Pell Library staff at the University of Rhode Island Graduate
          School of Oceanography for collecting many manuscripts and publications that
          were difficult to find. Comments, suggestions, and critical review of the manu-
          script by Peter Groffman, New York Botanical Garden, Institute of Ecosystem
          Studies; Heather Crawford, Connecticut Sea Grant; Elizabeth Gibbs and Tony -
          Corey, Rhode Island Sea Grant; and Laurie McGilvray, National Oceanic and,
          Atmospheric Administration, Office of Ocean and Coastal Resource Manage-
          ment,.greatly improved the finished document from earlier versions.






































           2








                 Table of Contents

                       Acknowledgments
                       1. Introduction      ......................................................................................................................................5
                            ï¿½ Definition of vegetated buffer             ......................................................................................................5
                            ï¿½ Multiple benefits         ..........................................................................................................................6
                       11. Vegetated Buffer Use and Effectiveness: A Review                          .....................................................................9
                            0 Nonpoint Source Pollution Control                  ...............................................................................................9
                            0 Critical Variables Affecting Pollutant Removal                     ...........................................................................9
                                       Surface Water Flow         ........................................................................................................... 10
                                       Groundwater Flow           ............................................................................................................. 10
                                       Slope    .................................................................................................................................. 11
                                       Soil Characteristics       ........................................................................................................... 12
                                       Pollutant Characteristics          .................................................................................................... 13
                                       VegetationType          ................................................................................................................. 14
                                          Grasses     ........................................................................................................................... 15
                                          Woody-stemmed Species              ................................................................................................. 18
                                       Buffer Width       ...................................................................................................................... 19
                                          Removal of sediment and suspended solids                   ................................................................... 21
                                          Removal of total and nitrate-nitrogen                ............................................................................ 24
                                          Removal of total phosphorus              ......................................................................................... 24
                                          Performance standards           .................................................................................................. 24
                            w Wildlife Habitat Protection             ........................................................................................................ 26
                            a Erosion and Flood Control             .......... :,** .............                                                                29
                            0 Historical and Cultural Preservation                .......................................................................................... 31
                            0 Scenic and Aesthetic Enhancement                   ............................................................................................ 31
                            0 General Guidelines for Multiple-use Vegetated Buffers                          ............................................................. 31
                            0 Implementation Approaches to Multiple-use Vegetated Buffer                               ................................................ 32
                                       The "Ideal" Buffer         ............................................................................................................ 34
                                          Contour     .......................................................................................................................... 34
                                          Vegetation      ...................................................................................................................... 34
                       III. Use of Vegetated Buffers in the Coastal Zone                        .......................................................................... 37
                            ï¿½ Application and Approach               .......................................................................................................... 37
                            ï¿½ Public Perception          ....................................................................................................................... 37
                            a Management and Maintenance                  .................................................................................................. 38
                            ï¿½ An Example: Rhode Island's Coastal Buffer Program                           ............................................................... 38
                            ï¿½ State Coastal Buffer Programs: A Summary                       .............................................................................. 39
                       IV. Selected Bibliography              .................................................................................................................. 47
                       V. Appendices        ..................................................................................................................................... 65
                       Appendix A - The Rhode Island Coastal Zone Buffer Program                               .......................................................... 65
                       Appendix B - The Rhode Island Coastal Zone Buffer Program: Management Guidance                                            ................... 69











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             1. Introduction                                              surface water runoff. As a result of their association
                                                                          with reducing the impact of development and
                 Recent events, such as algae blooms; fish kills;         landscape alteration on water resources, vegetated
             closure to harvest of finfish and shellfish stocks;          buffers are now being routinely employed as a tool
             increased coastal development, tourism, and recre-           for managing the environment. Vegetated buffers
             ation; loss of tidal wetlands and wildlife habitat; and      are often implemented, for instance, to mitigate the
             scenic degradation of coastal viewsheds, all have            effects of nonpoint source pollution by removing
             increased our awareness of the need to preserve,             pollutants from runoff through plant and microbial
             protect, and restore our nation's coastal resources.         uptake, microbial degradation and conversion,
             The problems observed along the coastal zone are             physical trapping, and chemical adsorption. Phillips
             not the result of any single event, but rather are a         (1989a) describes vegetated buffers as "one of the
             result of multiple changes that, when added together         most effective tools for coping with nonpoint source
             over time, have frayed and split the threads that link       pollution." The U.S. Environmental Protection
             together ecosystem functions. In response, manage-           Agency (EPA, 1993) states: "...constructing vegeta-
             ment schemes and regulations are developed that we           tive treatment systems, will be considered in all
             hope will slow the rate of ecosystem change,                 coastal watershed pollution control activities."
             smooth the frayed threads, and splice back together          Statements such as these give significance to the use
             the severed links. One such management effort can            of vegetated buffers, and further contribute to their
             be the application of vegetated buffers for use in the       adoption and use for the control of nonpoint source
             coastal zone. Vegetated buffers have been applied in         pollution in current resource management schemes.
             the fields of forestry and agriculture to moderate               Resource managers are beginning to view
             nonpoint source degradation of water courses, in             vegetated buffers as one method of working toward
             wildlife management to improve and provide                   compliance with recently drafted National Oceanic
             habitat, and in landscape architecture to improve            and Atmospheric Administration (NOAA) and EPA
             visual appeal. While great emphasis is being placed          nonpoint source pollution control measures. The
             on the use of vegetated buffers to abate nonpoint            practice of implementing vegetated buffers, how-
             source degradation of waterways, none of the above           ever, has generally focused upon their use as a "best
             uses are exclusive of the others. It makes both good         management practice" (BMP). Overall, there is a
             sense and good economics to pursue a multiple-use            lack of understanding with regard to developing
             application of the vegetated buffer concept in               vegetated buffers to provide benefits beyond what a
             coastal ecosystems.                                          typical BMP can provide. For instance, EPA (1993)
                 It is the intent of this document to formulate           states: "The term [vegetated buffer] is currently used
             concepts and ideas pertaining to the development of          in many contexts, and there is no agreement'on any
             vegetated regions along the coastal zone that pro-           single concept of what constitutes a buffer, what
             vide multiple benefits once implemented. It is not           activities are acceptable in a buffer zone, or what is
             the intent of this review to provide the specific            an appropriate buffer width." This statement empha-
             details, or provide critical comparison, of runoff           sizes the lack of general understanding and the
             sources and buffer effects when located on specific          common confusion concerning the use and effec-
             types of soils, for instance. There are many reviews         tiveness of vegetated buffers as a resource manage-
             of this type available in the published literature.          ment tool.
             This review differs from other published reviews of               Further confusion arises from the distinction,
             vegetated buffer uses in that it attempts to synthe-         noted in Table 1, between a vegetated filter strip and
             size a broad spectrum of buffer benefits, effective-         a naturally vegetated area. Filter strips are typically
             ness, and the variables that determine effectiveness.        considered a BMP engineered for a specific pur-
                                                                          pose, such as sediment removal. Forested buffers,
                 0 Derinition of vegetated buffer                         on the other hand, are typically natural areas left
                 Of the variety of definitions found in the litera-       along stream and river banks to mitigate the effects
             ture (Table 1), all include the concept of a vegetated       of logging on in-stream trout and salmon habitat.
             buffer acting as a transitional zone between differ-         These practices are commonly considered separate
             ing land uses, and/or as a barrier to, and filter of,        entities - one edge of field (filter strips) and the

                                                                                                                                   5










               other edge of stream (forested buffers)                 despite                 0 Multiple benefits
               their similarities in purpose. Together they make up                            Vegetated buffers often produce many benefits
               a range of functional uses greater than either consid-                     that are neither well-documented nor originally
               ered alone.                                                                intended. They can be used for providing wildlife
                   This review incorporates information taken from                        habitat; for promoting visual diversity; for bird
               both vegetated filter strip and forested buffer stud-                      watching, hiking, and picnicking; for preserving the
               ies, since the use of both is important in developing                      integrity of historical and cultural sites; for flood
               a general understanding of the effectiveness of                            zone management by setting development back
               vegetated buffers', particularly from a multiple-use                       from the immediate banks of waterways; and for
               perspective. When'the terin "vegetated buffer" is                          protecting structures from storm damage. Establish-
               used in this document, particularly with regard to                         ment of vegetated buffers throughout the coastal
               management implications for the coastal zone, it                           zone also can help provide for the long-tenn eco,-
               specifically refers to naturally vegetated areas. that                     nomic viability of the resource by maintaining an
               have been, or are being, set aside along the coast-                        aspect of the natural wilderness of the coast that
               line, whether grassy or wooded. When reference is                          draws people to'the shoreline.
               made to designing vegetated buffers where they                                  Vegetated buffer programs, however, are rarely
               presently do not exist, the intent is to develop a                         developed to fully consider the multiple benefits and
               vegetated area that mimics native vegetation appro-                        uses that they offer to resource managers and to the
               priate to the same locale. Our choice of the term                          general public. The "single use/single benefit"
               ,'vegetated buffer" keeps with its original use to                         approach used more often tends to alienate some
               designate naturally vegetated areas, but we develop                        sector of the public that does not view that single
               furt her the concept of multiple, use and multiple                         use/single benefit as a priority. Public awareness
               benefits for this versatile management tool, as                            that the vegetated buffers support multiple benefits
               adapted from information on both natural and                               - pollution control, wildlife habitat diversification,
               engineered vegetated buffers.                                              and scenic improvement, for instance - may lead
                                                                                          to more effective implementation, as well as giving
               Table 1. A selection of definitions for vegetated buffers.




                                   Reference                                                           Definition
                    Palfrey and Bradley, 1982                  Zones of undeveloped vegetated land extending from the banks or high water mark of a
                                                               water course or water body to some point landward. Their purpose is to protect the
                                                               water resources, including wetlands, they adjoin from the negative impacts of adjacent
                                                               land use.
                    Dillaha et al., 1986a                      Bands of planted or indigenous vegetation used to remove sediment and nutrients from
                                                               surface runoff.
                    Soil Conservation.Service, 1989            Strips of grass or other vegetation that trap pollutants from land areas before they
                                                               reach adjacent water bodies.
                    Chesapeake Bay Local Assistance Act,       An area of natural or established vegetation managed to protect other components of a
                    1990                                       Resource Protection Area and state waters from significant degradation due to land
                                                               disturbances.
                    Brown et al., 1990                         Transitional areas between two different land uses where one mitigates the impact
                                                               from the other.
                    Palmstrom, 1991                            Intended to provide a neutral area to lessen the impact of man's activities (i.e.,
                                                               fertilizer use, on-site septic systems, urban runoff) on sensitive resources.
                    Comerford et al.,  1992                    A barrier or treatment area protecting adjoining areas from the off-site effects of some
                                                               disturbance.
                    Dodd et al., 1993                           ..... strips of land in transitional areas between aquatic and upland ecosystems. From a
                                                               water quality management perspective, riparian buffers can be defined as areas designed.
                                                               to intercept surface and subsurface flow from upland sources for the purpose of
                                                               improving water quality.
                    EPA, 1993                                  Strips of vegetation separating a water body from a land use that could act as a
                                                               nonpoint source.




               6










             greater incentive for voluntary adoption and partici-       coastal zone ultimately derives its health. Anything
             pation in such programs.                                    less than a system-wide approach will result, as it
                 Before vegetated buffers can become an effec-           has in the past, in only partially solved problems.
             tive multiple-use management tool, however, their           The implementation of vegetated buffer programs,
             variable uses and effectiveness must be better              however, regardless of the environment in which
             understood by resource managers, who can then               they are applied or the care and effort taken in their
             develop programs to maximize the benefits and               design and development, can neither take the place
             minimize the shortfalls for their use along the             of, nor fully mitigate, the effects of poor land
             coastal zone. The implementation of vegetated               management techniques. Vegetated buffers should
             buffer areas in the coastal zone can directly assist in     be considered a tool that can assist in the restoration
             pollution control, habitat diversification, and visual      of coastal and watershed ecosystems once sound
             beautification. The application of multiple-use vege-       land management practices have been developed
             tated buffers, however, will best be implemented at         and put into general practice, and not as an inexpen-
             a watershed scale to protect the rivers and streams,        sive technological savior to mitigate poor land and
             and in effect, the entire ecosystem, from which the         other natural resource management practices.











































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               11. Vegetated Buffer Use and                                  along watercourses throughout the world. Many of
                                                                             these are engineered control measures designed to
               Effectiveness: A Review                                       mitigate the off-site impacts of development -
                                                                             catch basins, settling ponds, and grassy swales, for
                   0 Nonpoint Source Pollution Control                       instance. The implementation of vegetated buffers
                   Nonpoint source pollution of our nation's                 as BMPs has generally been practiced by resource
               waterways is of major concern for natural resources           managers with the intent of removing sediments and
               policy and management. The U.S. EPA recently                  attached pollutants from runoff water. This practice
               estimated that 50 to 70 percent of the nation's               is well-supported and documented in the literature,
               threatened or impaired surface waters were being              where numerous studies can be found that describe
               adversely affected by agricultural nonpoint source            the design and effectiveness of vegetated buffers as
               inputs, and that five to 15 percent of threatened or          a BMP. Other measures employ increased planning
               impaired surface waters were being adversely                  to abate the impacts of future development. Rezon-
               affected by urban runoff (Griffin, 199 1). Concern is         ing, cluster development, setbacks from water-
               also growing for the degradation of groundwater               courses, and defining naturally vegetated areas as
               due to nonpoint source impacts, which has implica-            buffers are some examples of planned mitigation
               tions with regard to subsurface recharge to streams,          measures. Naturally vegetated buffers have typically
               rivers, lakes, and estuaries, as well as to drinking          been applied as habitat preservation measures,
               water supplies. A national survey of wells con-               except within the field of forestry, where they have
               ducted by the U.S. Geological Survey found that               been extensively applied for sediment control.
               nearly 6.5 percent contained nitrate concentrations               In order to assess the potential value of imple-
               in excess of the EPA-established safe drinking water          menting vegetated buffers as a nonpoint source
               standard of 10 mg/l nitrate-nitrogen (Madison and             pollutant control measure, the many variables that
               Brunett, 1985).                                               affect how buffers remove pollutants from runoff
                   Recent estimates of the impact of nonpoint                must be understood. A better understanding of how
               source pollution have pushed forward a new era of             vegetated buffers work, and what factors limit their
               regulation to abate water quality degradation.                use and effectiveness as pollutant removal mecha-
               NOAA and EPA have both drafted new guidelines                 nisms, will assist in evaluation and implementation
               for regulations to limit nonpoint source pollutant            of practical and functional vegetated buffers.
               impact on surface waters. Under the purview of
               Section 6217 of the Coastal Zone Management Act                   E Critical Variables Affecting Pollutant
               and Section 319 of the Clean Water Act, the man-                       Removal
               dated regulation of nonpoint.source pollutants will               Vegetated buffers are typically employed with
               begin in earnest.                                             the primary objective of removing sediment and its
                   The control of nonpoint sources of pollution,             attached pollutants from surface water runoff. Pol-
               however, will not occur as easily as for point                lutant removal is primarily achieved by slowing the
               sources, which can usually be clearly identified,             surface water flow that transports sediments, allow-
               quantified, acted upon, and monitored for compli-             ing time for the settling of sediments and the pollut-
               ance to discharge standards. Nonpoint sources, by             ants adhered to them. The effectiveness of a veg-
               their very nature, are most often diffuse, cryptic, not       etated buffer in removing pollutants, however, will
               easily monitored, and in many ways not fully                  vary according to a number of conditions, such as:
               understood. A further problem is that, even when a                 - Soil type in the buffer
               nonpoint source is clearly identified, it is often not             - Depth of the water table in the buffer
               the sole cause of any observed degradation of water                - Type, density, and age of vegetation in the
               quality or habitat. Instead, it is usually a result of the             buffer
               cumulative impact of many nonpoint sources within                  - Pollutant concentrations contained in the
               the area.                                                              runoff water entering the buffer
                   Although numerous problems are inherent in                     - Land use and size of areas draining into the
               controlling nonpoint sources of pollution, abatement                   buffer
               methods are being developed and implemented

                                                                                                                                       9









                - Hydrologic regime of the area within and               limitation to buffer effectiveness during the review
                   adjacent to the buffer                                of riparian buffers implemented on agricultural
                - Width of the buffer                                    lands in the state of Virginia. Nearly all the veg-
                - Residence time of water in the buffer                  etated buffers inspected. needed some form of
                - The path of runoff water into   and through the        maintenance or engineering to reduce channeli-
                   buffer                                                -zation of flow, and to increase effectiveness in the
                                                                         removal of sediment and pollutants from surface
                Due to the inherent variability in the conditions        runoff. The natural tendency of water to move in
          that determine the effectiveness of vegetated buffers          discrete channels may be one of the greatest impedi-
          for the removal of pollutants, no single "best buffer"         ments to successful buffer implementation for
          has been identified for widespread application.                nonpoint source pollution control, particularly when
          However, with better definition of those variables             implementing nonengineered vegetated buffers.
          that  -determine buffer effectiveness, a better under-             When depth of the surface water flow is such
          standing can be gained as to what conditions, in               that vegetation in the buffer is submerged, effective-
          general, promote pollutant removal effectiveness.              ness is reduced. As submergence increases, filtering
                                                                         efficiency of the buffer declines to zero (Karr and
          Surface Water Flow                                             Schlosser, 1978; Barfield et al., 1979). When storm
                In order for a vegetated buffer to effectively           events occur, such as sudden thunderstorms, precipi-
          remove pollutants and sediments, the surface water             tation.can often be extremely, heavy, submerging; the
          flow through the vegetated buffer must be slow,                buffer and allowing an initial heavy flow of pollutants
          shallow, and uniform (Broderson, 1973; Dillaha et              into receiving waters. All vegetated buffers may exper-
          al., 1986a). Surface water runoff should progress as           ience temporary ineffectiveness during thunderstorms
          shallow "sheet flow," and not become channelized               or similar events that bring heavy precipitation.
          as it moves across the buffer area. Slow flow allows
          for pollutants - which are often adsorbed to                   Gr oundwater Flow.
          sediments - to settle out and become incorporated                  As surface soils become saturated, water may
          into surface soils (Lee et al., 1089). Settling will be        move vertically rather than horizontally through the
          most pronounced in runoff that contains large-sized            soil layer and enter into the groundwater recharge
          sediment particles, and less pronounced in those               system. The net movement of groundwater depends
          containing fine silts and particulates, which often            on soil type, subsurface impermeable layers, geol-
          require long retention times and Very slow flows in            ogy, hydrologic regime, and slope. Groundwater
          the vegetated buffer to effectively settle. Slow flow          carries soluble pollutants that have passed through
          also promotes utilization of nutrients by plants,              soils in percolated water. As it eventually recharges to
          assists flood control by allowing water to percolate           lakes, rivers, streams, and coastal waters, it can be-
          into the soil, and reduces erosion within the buffer           come a source of pollution to surface waters. Ground-
          area. Rough surfaces, which better reduce flow                 water may also move into -subsurface aquifers and
          velocity and promote sheet flow, result in greater             degrade potable water supplies. In areas such as the
          pollutant and sediment removal than smooth sur-                coastal northeastern United States, groundwater
          faces (Flanagan'et al., 1986;"Williams and Nicks,              recharge can be a: significant source of nitrogen
          1988).,                                                        enrichment to coastal waters (Valiela et al., 1992;
                Field tests, however, indicate that naturally            Weiskel and Howes, 1992). Leachate from septic
          occurring vegetated buffers are generally incapable            tanks, leaking underground storage tanks, landfills,
          of inducing sheet flow from storm water runoff due             and accidental spills can all enter the groundwater
          to the natural tendency of water to move in discrete           system, eventually entering coastal waters.
          channels. Dillaha et al. (1986a) report a range of 40              Vegetated buffers, however, may only be able to
          to 95 percent reduced efficiency of sediment, nitro-           remove a limited number of pollutants from ground-
          gen, and phosphorus r    ernoval in vegetated buffers          water - nutrients and some metals, for instance.
          when runoff flow through the buffer area deviated              Oils, most metals, and pesticides will generally not
          from shallow sheet flow. Channelization. of flow               be effectively removed by vegetated buffers once
          through the buffer was cited as a major problem and            they have entered the groundwater recharge system.

          10










              Furthermore, vegetated buffers located over deep             removal of nitrate contained in both surface and
              water tables are not usually effective in the removal        groundwater supplies. A series of related studies by
              of pollutants from subsurface flow. Deep groundwa-           Gold et al. (1991), Simmons et al. (1992), and
              ter flows can move over considerable distances and           Groffman et al. (1992), reported that nitrate removal
              over relatively long time frames (Hynes, 1983), and          was greater in areas with shallow water tables than
              at depths where plant root systems are unlikely to           in those with deep water tables during both dormant
              reach them. Areas that are recharged from deep               and growing seasons. Ambus and Lowrance (1991)
              groundwater flows often receive pollutant inputs             found that 68 percent of the denitrification they
              from distant sources that may have originated                observed occurred in the top two centimeters of soil.
              decades ago. A time lag may therefore develop                A shallow water table keeps groundwater close to
              between both cause and effect, as well as between            the surface and in the area where carbon sources
              the implementation of abatement measures and any             (i.e., organic leaf litter) are most likely to promote
              observable effects.                                          the growth of denitrifying microbes. Correll and
                  Nutrient uptake and utilization by plants can be         Weller (1989), based on biomass removal estimates
              a major pathway of nutrient removal from ground-             for nitrate-nitrogen, suggest that denitrification may
              water supplies in a vegetated buffer. In areas that          be the most important nitrate removal mechanism
              contain a shallow aquaclude (a subsurface imperme-           from groundwater in forested areas.
              able soil layer), subsurface flow may be more                    There is, however, some concern that use of
              horizontal than vertical, increasing the likelihood of       vegetated buffers to treat surface water runoff may
              groundwater being reached by the roots of overlying          actually increase groundwater nitrate and other
              vegetation. In a forested area located over a shallow        soluble pollutant concentrations by promoting
              aquaclude (less than four meters deep), Peterjohn            percolation into soils. Gold et al. (1989) and
              and Correll (1984) reported an 80 percent removal            Weiskel and Howes (1992) have both reported that
              of nitrate from surface water flow, and Correll and          nitrate can readily travel through soils and into
              Weller (1989) reported an 84 to 87 percent removal           groundwater supplies with little or no removal in
              of nitrate from groundwater. In these instances the          transit. This may be true for many soluble forms of
              subsurface aquaclude kept the groundwater avail-             pollutants, particularly in areas with highly penne-
              able to the root systems of plants in the buffer for         able or very well-drained soils (Schwer and
              uptake, as well as keeping it available to denitrify-        Clausen, 1989). Under some soil conditions - well-
              ing microbial communities.                                   drained, sandy soils, for instance - the vegetated
                  A major pathway for nitrate removal in ground-           buffer could slow surface flow, promoting rapid
              water is denitrification. The process of denitrifica-        percolation of surface water to groundwater, and
              tion, which converts nitrate to nitrogen gas, which is       actually degrade potable water supplies or coastal
              then released to the atmosphere, is reliant upon the         waters. It is presently unclear, however, to what
              existence of a microbial community of denitrifying           extent this event occurs, and further study is needed
              bacteria. The microbial community is partly reliant          to determine if and when vegetated buffers promote
              upon anaerobic conditions - a circumstance in                groundwater contamination.
              which no free oxygen is present. The oxygen
              present in nitrate (NO 3) is utilized for metabolism         Slope
              by the microbial community, and nitrogen gas is                  Areas of steep slope do not allow for long
              released to the atmosphere as a metabolic by-                retention time of runoff water, and since pollutant
              product. A further limitation to this process is the         removal is at least partially time-dependent (i.e., to
              availability of a source of carbon (organic material)        allow plant uptake and deni'trification to occur),
              to support the microbial community (Obenhuber                steep slopes reduce vegetated buffer effectiveness.
              and Lowrance, 1991). Soils that are poorly drained           Furthermore, steeply sloped areas negate the veloc-
              and rich in organic materials will typically provide         ity-reducing effects of surface roughness, and
              conditions that promote denitrification.                     thereby promote erosion. Even though a steeply
                  Areas with a shallow water table, such as                sloped area may be thickly vegetated, it may be
              wetlands and areas with poorly drained soils, most           ineffective at removing sediments and pollutants
              readily provide the conditions conducive to the              because it promotes erosion and channelization of









           flow through the buffer area. The shallower the                   be deposited on the leading edge of the buffer area,
           slope, the longer the residence time, the slower the              forming a berm (Magette et al., 1986; Robat and.
           flow, and the greater the ability of sediment and                 Sabol, 1988). Once a berrn is formed at the leading
           pollutants to settle and be removed from the runoff.              edge of the vegetated buffer, water will be chan-
               A slope of less than 15 percent reportedly                    neled around the buffer, rendering it uselesg. Even-
           allows for adequate retention time and pollutant                  tually the berm will be breached, causing
           removal, while steeper slopes may not be suitable                 channelization of flow into the vegetated buffer,
           for vegetated buffers due to the slopes'erosion                   increasing erosion and reducing buffer effectiveriess
           potential and lack of adequate retention time                     for pollutant and sediment removal.
           (Schueler and Bley, 1987; Niewswand et al., 1990;
           Palmstrom, 1991). Clark (1977) gives some ex-                     Soil Characteristics
           amples of minimum buffer widths for water quality                     Soils with high pen-neability generally provide
           protection according to slope and soil erodibility: he            greater filtration of sediment and attached pollutants
           recommends a minimum width of 10 meters for                       (Chescheir et al., 1988; Lee et al., 1989). Once the
           areas with no slope on slightly erodible soils,                   pollutants enter the soil layer, they can become
           extending to 50 meters for 30-percent slopes on                   incorporated through physical, chemical, and
           severely erodible soils. Trimble and Sartz (1957)                 biological interactions. However, highly permeable
           suggest adding an extra 0.6 meters of vegetated                   soils, such as sandy soils, may allow for the rapid
           buffer width for each one'--percent increase in slope             movement of water into the groundwater recharge
           within the vegetated bufferfor minimum effective-                 system. The movement may be so rapid that no
           ness, and a 1.2-meter increase per one percent slope              removal of pollutants is'allowed by plants, and only
           increase to attain greatest water quality protection.             minimal removal by physical and chemical adsorp-
           Broderson (1973), in a study of the effectiveness of              tion, particularly for dissolved forms of pollutants.
           forested buffers to remove sediment from runoff                        Figure 1 shows that well-drained soils are only
           before the runoff enters a stream, suggests that                  half as effective for the removal of nitrogen as
           fifteen-meter buffers are sufficient at slopes less               poorly drained soils. Sandy soils provided the least
           than 50 percent, and a maximum 66-meter buffer is                 nitrogen removal, regardless of drainage capacity'
           sufficient for extremely sloped areas. Comerford et               Ehrenfeld (1987) found that nitrogen from septic
           al. (1992) note, from a review of the literature, that            system leachate moved greater distances vertically
           slopes greater than 30 percent generally allow                    than horizontally through the permeable sandy soils
           inadequate retention time in a vegetated buffer for               of the New Jersey Pinelands, where the nitrate-laden
           any significant denitrification to occur.                         septic leachate quickly percolated below the root
               Slope of the area preceding the vegetated buffer              zone of buffer vegetation. In some soils, vegetated
           also can affect pollutant and sediment removal.                   buffers that are not located directly in the septic
           Steep slopes leading into a flat buffer area often                system leach field plume will be ineffective in
           tend to cause the bulk of the transported sediment to             removing nitrate. The contaminants contained in


               Figure 1. Nitrogen removal in                           sand                  loam                    clay-loam
               various poorly drained and well-
               drained soil types. Nitrogen             Poorly drained
               removal is more than doubled in
               poorly drained soils compared to
               well-drained soils. Sandy soils                         sand     loam     clay-loam
               provided poor nitrogen removal
               regardless of soil wetness. Data            Well-drained
               from Groffman and Tiedje, 1989a.

                                                                       0  5     10     15.   20    25     30    35    40     45    @0
                                                                                         Nitrogen Removal (kg/N/ha)



           12








             septic system leachate can readily enter nearby              consistently removed. Other metals may therefore
             waterways under these conditions.                            not be effectively removed from surface runoff by
                 Poorly drained soils generally retain water long         vegetated buffers, even in buffers with conditions
             enough, and often under conditions favorable                 conducive to metals removal, and other methods
             enough, that pollutant removal is accomplished.              may need to be explored if removal of metals is of
             Figure I presents a range of nitrogen-removal data           major concern.
             reported by Groffman and Tiedje (1989a) for a
             variety of soil types and conditions. Poorly drained         Pollutant Characteristics
             soils were found to be more than twice as effective             Many studies indicate that most pollutants and
             as well-drained soils for the removal of nitrogen.           nutrients transported by surface runoff are attached
             Poorly drained soils that contain a higher organic           to sediments. This tends to be true for metals
             content are more apt to promote the growth and               (Zirschky et al., 1989), pesticides (Lake and
             maintenance of denitrifying microbial communities            Morrison, 1977), phosphorus (Karr and Schlosser,
             and hence greater nitrogen removal (Nichols, 1983;           1977; Chescheir et al., 1988; Lee et al., 1989), and
             Peterjohn and Correll, 1986; Groffman et al.,                some forms of nitrogen (Karr and Schlosser, 1977;
             199 1 a). In cases where long residence time occurs          Chescheir et al., 1988). Nitrate, however, has less
             in saturated, organic soils, nitrogen removal may be         affinity to sediments, and is most often found in a
             high (Cooper, 1990). These conditions are typically          dissolved phase (Chescheir et al., 1988). Runoff that
             found in salt marshes, wetlands, and wet forests, all        characteristically contains pollutants bound to
             of which have been repeatedly reported to express            sediment need only move through a buffer able to
             high denitrification potential. Saturated, organically       remove the sediment load. When runoff characteris-
             rich soils, therefore, can be useful in the removal of       tically carries pollutants in dissolved or soluble
             both soluble and sediment-bound pollutants, while            forms, the buffer area will need to promote long
             sandy soils may be most effective in removing                retention times in order for those pollutants to be
             sediments and bound pollutants, and soluble forms            effectively adsorbed to soils or utilized by plant and
             only marginally.                                             microbial communities.
                 Soils rich in clay content are often relatively             The effectiveness of pollutant removal will be
             impermeable, and removal of pollutants from                  related to the concentration of pollutants entering
             surface waters by soil percolation can be low.               the vegetated buffer from outside sources. Much of
             Scheuler and Bley (1987) do not recommend                    the reviewed literature reports testing buffer effi-
             vegetated buffers as effective pollutant removal             ciency in response to sources that have very high
             mechanisms in clay-rich soils. Mixed clay soils,             concentrations of incoming pollutants, particularly
             however, as shown in Figure 1, often are effective in        sediments and nutrients. For instance, Edwards et al.
             the removal of pollutants. Clay soils often have high        (t983) measured concentrations of total suspended
             affinities for binding positively charged pollutants,        solids, nitrogen, and phosphorus entering grassed
             particularly metals, by acting as a cation (negatively       buffers from a cattle feedlot to be: 10,200 mg/l TSS;
             charged) exchange site. Provided the clay soils are          705 mg/l N; 152 mg/l P. In most cases, very favor-
             not compacted, and runoff over the area is slow,             able removal efficiencies were reported, despite a
             pollutant removal via chemical binding may be                high input rate. In the Edwards et al. (1983) study,
             significant (Zirschky et al., 1989). Chemical re-            removal rates of 87 percent TSS, 83 percent N, and
             moval, however, is finite: once metals are adsorbed          84 percent P were recorded after the feedlot runoff
             to soils, they can be freed for transport by further         had moved through a settling basin and sixty meters
             chemical or physical disturbance of the soil layer,          of grassed buffer. This may suggest that vegetated
             and may be moved during the next runoff event. A             buffers treating more "average" concentrations of
             ranking of stability of soil-bound metals given in           pollutant inputs might produce even greater removal
             Baker and Chesnin (1975) shows that copper has the           efficiencies than those reported in the published
             greatest tendency to remain stable once adsorbed.            literature (see Schueler (1987), for example, for
             Zirschky et al. (1989), experimenting with copper,           average concentrations of various pollutants con-
             nickel, zinc, cadmium, chromium, iron, lead, and             tained in urban runoff water).
             manganese, found that only copper and zinc were                  In contrast, Nichols (1983) reported that re-

                                                                                                                                 13









          moval efficiency for nitrogen and phosphorus                dramatically. Wong and McCuen (1982) similarly
          decreased as loading of those nutrients into a              found that disproportional increases in buffer width
          wetland treatment area increased. Reuter et al.                from 33 to 66 meters - were required to in-
          (1992) report similar results. The U.S. Army Corps          crease sediment removal efficiency of a grassed
          of Engineers (199 1) suggests that, despite reported        buffer from 90 to 95 percent. The largest sediment
          high removal efficiencies for pollutants in vegetated       particles are generally deposited within the first few
          buffers, high pollutant loading rates into the buffer       meters of the vegetated buffer, leaving the fine silts
          may result in degradation of adjacent sensitive water       and clays in suspension. For example, Neibling and
          bodies. For example, Castelle et al. (1992) reported        Alberts (1979) reported that only 37 percent of clay-
          that 55 percent of the assessed buffers implemented         sized sediment and particulates were removed
          to protect wetlands that bordered residences using          within a 0.6 meter width of grass vegetated buffer,
          lawn, maintenance systems showed impacts from               while 91 percent of the"total sediment load was
          fertilizer applications. The sympto ins ranged from         removed within the same effective buffer width..
          increased wetland plant growth'to wetland plant             Wilson (1967) found that most coarse-grained
          -death from nitrogen  toxicity. Under high pollutant        sediment was removed in 3.3 meters, most silt in 15
          loading conditions, the percentage of pollutants not        meters, and most clays by 90 meters in a buffer
          removed may be sufficient to cause degradation of           vegetated with Bermuda grass.
          water quality and other resources. This is further              Relatively narrow buffers, provided they pro-
          exemplified by the study of Edwards et al. (1983),          mote shallow sheet flow through the buffer area,
          in which, despite high removal rates (87 percent            will effectively remove coarse-grained sediments
          TSS, 83 percent N, 84 percent P), the pollutant load        and their associated pollutants. Wider buffers,
          leaving the sixty-meter grass buffer was high (988          however, will be required to remove smaller-sized
          kg TSS, 63 kg N, 15 kg P), as were concentrations           particles of sediment and the pollutants adsorbed to
          (3,840 mg/l TSS; 260 mg/I N; 51 mg/l P). Although           them. Pollutants in dissolved forms may require
          high pollutant removal rates in vegetated buffers           even greater buffer width to be effectively removed
          will certainly reduce loadings to receiving water,          by chemical interactions, plant uptake, or microbial
          they may not necessarily equate to protection of            transformation.
          water quality.
              Over time, a vegetated buffer may become                Vegetation Type
          "saturated" with sediments and pollutants, reducing             The vegetative ground cover within a buffer
          overall removal efficiency. Eventually the buffer           serves multiple purposes with regard to overall
          could become a source of pollutants to adjacent             buffer effectiveness by removing pollutants, provid-
          water bodies. It is well known that physical distur-        ing.habitat, and creating aesthetic appeal. The type,
          bance can cause pollutants trapped in a vegetated           density, and age of the vegetative ground coverplay
          buffer to become available for transport out of the         a large role in determining the effectiveness of .              I
          buffer area. However, not enough research has been          pollutant removal, the habitat value to wildlife, and
          conducted on vegetated buffers to adequately assess         the overall aesthetic appeal of the vegetated buffer.
          either the conditions that lead to saturation with          The vegetative ground cover contained in a buffer
          pollutants or the circumstances under which an un-          can be manipulated, often in a cost-effective man-
          disturbed vegetated buffer becomes a pollutant source.      ner, to better achieve the goals for which the veg-
              Karr and Schlosser (1977) note that pollutants          etated buffer was implemented. For instance, the
          contained in surface runoff are generally bound to          vegetative cover in the buffer could be manipulated
          smaller-sized sediment particles, such as silts and         to enhance the removal of various pollutants of
          clays, and that the effectiveness of any vegetated          concern, thereby providing some flexibility to
          buffer will partially depend on how well it removes
                                                                      resource managers, for achieving their specific goals.
          silts and clays from runoff water. Clay sediment in            Table 2 provides a range of removal rates
          runoff generally exists at very small sizes, and Karr       reported in the literature for nitrogen, phosphorus,
          and Schlosser (1978) report that, ag particle size          and sediment in both g'rassed and forested buffers
          decreases, the buffer width required to remove a            and over a variety of site-specific conditions.
          greater percentage of those particle sizes increases        Nitrogen was the most widely reported pollutant

          14









              with regard to removal in vegetated buffers. The            where the primary pollutant of concern is sediment
              removal rates provided in Table 2 may be useful to          (and its adsorbed pollutant load). The results of
              resource managers for estimating potential nitrogen         grassed buffer studies are generally reported as
              removal in implemented buffers, based upon vegeta-          percent removal and typically have treated source
              tion and other general characteristics. In the event        areas with a high pollutant load. Studies of wooded
              that pollutant loadings were able to be estimated,          buffers generally have focused on naturally forested
              actual removal rates for a proposed vegetated buffer        areas, with the removal of nitrogen the primary
              could be estimated, based upon Table 2 and site-            focus. Nitrogen removal typically is through bio-
              specific data, and the buffer area modified in order        logical rather than physical/chemical pathways,
              to achieve the desired pollutant removal goal.              such as denitrification and plant uptake and storage.
                  The removal rate values for nitrogen presented          Forested buffer studies less often reported source
              in Table 2 are graphically presented in Figure 2 to         areas that contained high pollutant loads, and
              visually show the range of nitrogen removal rates in        generally treated logged or urban areas rather than
              grassed and forested buffers. The range of nitrogen         livestock and agricultural areas. The result is very
              removal rates represented in Figure 2 shows that,           much two separate bodies of knowledge, which
              overall, grassed buffers have greater nitrogen              have taken two separate paths of study. This makes
              removal potential than forested buffers. Forested           for some difficulty in directly comparing grassed
              areas, particularly wet forests, are frequently noted       and forested buffer studies, as the methods and
              in the published literature to be more effective            reporting of results are generally different. Enough
              nitrogen removers than grassed areas. In Figure 2,          of each, however, has been reported in similar units
              however, grassed buffers are shown to have the              that some preliminary comparisons can be made and
              potential to remove nitrogen at a rate approximately        relationships proposed.
              three times greater than that of forested areas. The
              potential for forested areas to remove nitrogen may              Grasses
              be underestimated in the presented data, since some              Grasses tend to be very effective in reducing
              of the grassed buffers were treated with direct             overland flow, as well as being effective nutrient
              nitrogen applications (fertilizers), thus providing a       and sediment removers. Removal rates reported in
              greater representation of their overall nitrogen            Table 2 and used in Figure 2 show that grassed buf-
              removal potential. Studies conducted with forested          ffers treated with fertilizer applications can remove
              buffers generally did not include fertilizer treat-         up to 290 kg N/ha/yr. Despite high reported removal
              ments; therefore, their range of potential nitrogen         rates and efficiencies, it is often unclear how this re-
              removal may be underestimated. However, unfertil-           lates to water quality protection. Morton et al.(1988)
              ized control plots of Kentucky bluegrass utilized by        found nitrate leachate concentrations leaving fertil-
              Morton et al. (1988) had removal rates of only 2.0          ized plots of Kentucky bluegrass to be well below
              kg/N/ha/yr, which is considerably lower than the            the EPA drinking water standard of 10 mg/I nitrate-
              lowest removal rates reported for forested areas (see       nitrogen. Nitrate concentrations ranged from 0.51 to
              Table 2 and Figure 2). Furthen-nore, fewer studies          4.02 mg/l, with the higher values found leaving
              for grassed buffers reported removal in kg/ha/yr            heavily fertilized, overwatered experimental plots.
              than for forested buffers, and the average removal          The  *results of this study suggest that home lawn
              rate for grassed buffers may more closely approxi-          fertilization practices may not always pose a direct
              mate those for forested, given greater representation       threat to drinking water supplies. Although these
              (see Figure 2).                                             reported concentrations do not appear threatening to
                  Grasses and woody-stemmed species are de-               potable water supplies, concentrations at the upper
              scribed separately below because of the unique              portion of the range could, when combined with
              characteristics of each type, as well as the differ-        other sources of nitrogen, contribute to eutrophica-
              ences each group exhibits in the removal of sedi-           tion of coastal waters. This may be particularly true
              ment and pollutants from runoff. Furthermore, the           in the temperate coastal zone, where soils are
              literature on the two types of ground cover is very         typically composed of glacial till and sand, which
              different. Most of the work completed for grass             often allow rapid movement of groundwater to
              buffers comes from studies of vegetated filter strips       coastal waters with only minimal removal of nitrogen.

                                                                                                                                  15










              Table 2. Removal rates for various pollutants in vegetated buffers. The values reported for removal in grassed buffers may
              be high relative to forested buffers because most received direct fertilizer treatments, whereas forested buffers did not. Removal
              rates for forested buffers may therefore be underestimated with regard to their actual removal potential. [1 kilogram                                2.2
              pounds; I hectare = 2.47 acres]



                           Reference                            Removal Rate                                            Details
                   NITROGEN
                   Ehrenfeld, 1987                              75 - 80 kg NAWyr          Hardwood wetland getting septic tank leachate
                   Ehrenfeld, 1987                              45 - 56 kg N/ha/yr        Pine upland getting septic tank leachate
                   Ehrenfeld, 1987                              68 - 69 kg N/ha/yr        Oak upland getting septic tank leachate
                   Peterjohn & Correll, 1984                    77 kg N/ha/yr             Mid-Atlantic coastal plain forest trees
                   Palazzo, 1981                                290 kg N/ha/yr            Orchard grass; sewage waste treated
                   Fail et al., 1986                            50 kg N/ha/yr             Plant uptake and storage in a coastal plain riparian forest
                   Cole & Rapp, 1981                            75.4 kg N/ha/yr           Mean of 14 temperate deciduous forests
                   Lowrance et al., 1984c                       51.8 kg N/ha/yr           Aboveground plant storage in riparian forests
                   Lowrance et al., 1984c                       31.5 kg N/ha/yr           Denitrification in riparian forests
                   Morton et al., 1988                          2.0 kg N/ha/yr            Kentucky bluegrass control plot
                   Morton et al., 1988                          32 kg N/ha/yr             Kentucky bluegrass; overwatered and fertilized
                   Brown & Thomas, 1987                         194 kg N/ha               Bermuda grass on sandy soils with repeated harvesting
                   Peterjohn & Correll, 1984          11 kg/ha particulate organic N      Riparian forest treating agricultural watershed
                   Peterjohn & Correll, 1984             0.83 kg/ha ammonium N            Riparian forest treating agricultural watershed
                   Peterjohn & Correll, 1984                    2.7 kg/ha nitrate N       Riparian forest treating agricultural watershed
                   Peterjohn & Correll, 1984                    45 kg/ha nitrate N in     Riparian forest treating agricultural watershed
                                                                groundwater
                   Groffman & Tiedje, 1989a                     10 kg N/ha/yr             Well-drained loam
                   Groffman & Tiedje, 1989a                     I I kg N/ha/yr            Somewhat poorly drained loam
                   Groffman & Tiedje, 1989a                     24 kg N/ha/yr             Poorly drained loam
                   Groffman & Tiedje, 1989a                     18 kg N/ha/yr             Well-drained clay-loam
                   Groffman & Tiedje, 1989a                     17 kg N/ha/yr             Somewhat poorly drained clay=loam
                   Groffman & Tiedje, 1989a                     40 kg N/ha/yr             Poorly drained clay-loam
                   Groffman & Tiedje, 1989a                     0.6 kg N/ha/yr            Well-drained sand
                   Groffman & Tiedje, 1989a                     0.8 kg N/ha/yr            Somewhat poorly drained sand
                   Groffman & Tiedje, 1989a                     0.5 kg N/ha/yr            Poorly drained sand
                   Groffman et al.,   1991 a                    311 g NAWday              Well-drained aerobic forest soil with nitrate added
                   Groffman et al.,   1991a                     365 g N/ha/day            Poorly drained aerobic forest soil with nitrate added
                   Groffman et al.,   1991a                     7,889 g NAWday            Tall fescue on aerobic soil with nitrate added
                   Groffman et al.,   1991a                     4,537 g N/ha/day          Reed canary grass on aerobic soil with nitrate added
                   Groffman et al.,   1991a                     1. 1 g NftWday            Well-drained anaerobic forest soil, no nitrate added
                   Groffman et al.,   1991 a                    1,306 g N/ha/day          Well-drained anaerobic forest soil, nitrate added
                   Groffman et al.,   1991a                     13.1 g N/ha/day           Poorly drained anaerobic forest soil, no nitrate added
                   Groffman et al.,   1991a                     1,402 g N/ha/day          Poorly drained anaerobic forest soil, nitrate added
                   Groffman et al.,   1991a                     1.0 g N/ha/day            Tall fescue on anaerobic soil, no nitrate added
                   Groffman et al.,   1991a                     17,208 g N/ha/day         Tall fescue on anaerobic soil, nitrate added
                   Groffman et al.,   1991 a                    1.0 g NAWday              Reed canary grass on anaerobic soil, no nitrate added
                   Groffman et al.,   1991a                     15,208 g NftWday          Reed canary grass on anaerobic soil, nitrate added
                   Warwick & Hill, 1988                  0.05--0.53pg N/m2/day            Sandy sediments
                   Warwick & Hill, 1988                  0.08-1.20 pg N/m      ,2/day     Organic sediments
                   Warwick & Hill, 1988                  1.05-3.19 gg N/M2/day            Watercress bed detritus and sediments
                   Hook & Kardos, 1977                          388 kg N/ha/yr            Reed canary grass; sewage waste treated
                   Rhodes et al., 1985                   0.341-7.265 g N/hr/acre          Mean of I 11 high-altitude wet meadow samples
                   Lemunyon, 1991                               99.3 / 37.5 kg N/ha       Smooth Bromegrass in 15m2 well-drained plot; urea treated
                   Lemunyon, 1991                               56.1 /20.6 kg N/ha        Garrison grass in 15m2 well-drained plot; urea treated
                   Lemunyon, 1991                               73.9 / 48.9 kg N/ha       Kentucky bluegrass in 15m2 welTdrained plot; urea treated
                   Lemunyon, 1991                               87.6 / 38.4 kg N/ha       Orchard grass in 15m2 well-drained plot; urea treated
                                                                                          Perrenial ryegrass in 15m2 well-drained plot; urea treated


              16










                 Table 2. Removal rates for various pollutants in vegetated buffers. Continued



                        Lemunyon, 1991                           80.9 / 34.1 kg N/ha           Reed canary grass in 15m2 well-drained plot; urea treated
                                                                 65.2 / 3 3.5 kg N/ha
                        Lemunyon, 1991                                                         Sweet vernal grass in 15m well-drained plot; urea treated
                        Lemunyon, 1991                           78.2 / 37.9 kg N/ha           Tall fescue in 15m2 well-drained plot; urea treated
                        Lemunyon, 1991                           40.5 / 11.7 kg N/ha           Big bluestern in 15m2 well-drained plot; urea treated
                        Lemunyon, 1991                           29.1 / 18.5 kg N/ha           Switcligrass in 15m2 well-drained plot; urea treated
                        Hill & Sanmugadas, 1985                37-412 mg N/m2/day              24-hour stream sediment incubation
                        Hill & Sanmugadas, 1985                33-223 ing N/m 2/day            48-hour stream sediment incubation
                        Schellinger & Clausen, 1992              0.72 kg/m 21yr TKN            22.9 X 7.6m mixed species grass buffer; 2% slope
                        Schellinger & Clausen, 1992         0.32 kg/m 2/yr Ammonia-N           22.9 X 7.6m mixed species grass buffer; 2% slope
                        PHOSPHORUS
                        Peterjohn & Correll, 1984           3.0 kg/ha total particulate P      Riparian forest treating agricultural watershed
                        Lowrance et al., 1984c                      3.8 kg P/ha/yr             Aboveground plant storage in riparian forests
                        Schellinger & Clausen, 1992               0. 15 kg/m 2/yr TP           22.9 X 7.6m mixed species grass buffer; 2% slope
                        Schellinger & Clausen, 1992          0. 12 kg/m 2/yr Dissolved p       22.9 X 7.6m mixed species grass buffer; 2% slope
                        Schellinger & Clausen, 1992            0.09 kg/m 2/yr Ortho P          22.9 X 7.6m mixed species grass buffer; 2% slope
                        Cole & Rapp, 1981                           5.6 kg P/ha/yr             Mean of 14 temperate deciduous forests
                        SEDIMENT & OTHER
                        Peterjohn & Correll, 1984           4.1 kg/ha/yr of particulates       Riparian forest treating agricultural watershed
                        Schellinger & Clausen, 1992               1. 13 kg/m 2/yr TSS          22.9 X 7.6m mixed species grass buffer; 2% slope






                 Figure 2



                        Figure 2. Ranges of nitrogen removal
                        for grass and forested buffers. The
                        heavy line contained in the bar                       Grass                                                                              N  3
                        represents the mean of the data that
                                                                                                                               n              W@v
                        constitute the range. Data taken from
                        Table 2. [1 kilogram        2.2 pounds; I
                        hectare     2.47 acres]

                                                                              Forest                        N=7




                                                                                    0            50          100          150          200           250         300
                                                                                                           Nitrogen Removal (kg/N/ha/yr)













                                                                                                                                                                           17









               Grasses are desirable as part of the vegetative         removal of pollutants from groundwater (Ehrenfeld,
          matrix that constitutes the vegetated buffer. They are       1987;  Groffman et al., 199 1 b). In general, hardwood
          generally able to respond rapidly to increased               species .are better nitrogen removal mechanisms
          concentrations of nutrients, grow rapidly and                than are conifer species (Spur and Barnes, 1980),
          densely, and typically grow well in nearly all               but the overall removal of pollutants will vary
          climates. Thickly planted, clipped grasses provide a         according to characteristics of the forested buffe-r
          dense, obstructive barrier to horizontally flowing           site - such as vegetative composition, depth to the
          water. This increases the roughness of the terrain,          water table, and hydrology.
          which reduces flow velocity, promotes sheet flow,                For wooded buffers, poorly drained forest plots
          and inc 'teases sediment and adsorbed pollutant              have been found to provide greater denitrification
          removal efficiency. This also increases residence            than well-drained forest plots by creating better
          time in the buffer, which promotes uptake of nutri-          living and growth conditions for denitrifying mi-
          ehts by plants. Low-cropped grasses, however, may            crobes, as well as by keeping water within the organ-
          not be adequate in areas that-experience frequent            ically enriched surface soil layer 'and close to root
          flooding, as they are rendered temporarily useless           systems of resident vegetation (Correll, 1991; Groff-
          when submerged. Grasses that are to be used as part          man et al., 1992). Figure 2 shows removal rates as
          of the vegetated matrix of the buffer should there-          high as 85 kg N/ha/yr have been reported for nitro-
          fore be left in an uncut condition, or at least not cut      gen removal in forested areas. The range of nitrogen
          below a height of three or four inches. A worst-case         removal rates for forested buffers is small, suggest-
          grassed buffer would be one that is highly mani-             ing that removal and storage in these sites are, on
          cured and clipped low, resembling a golf course              average; fairly consistent. With regard to plant
          putting green. These become flooded very easily,             uptake, Ehrenfeld (1987) found that brush species
          thus being rendered useless as a pollutant filter.           did not show an increased nitrogen content *in the
          Medium height, thickly growing grasses represent             presence of septic system leachate, while hardwood
          the ideal for a grassed buffer area.                         and conifer species did. This suggests that species
              The use of grasses in vegetated buffers has              with shallow root systems may often be ineffective
          many maintenance benefits. Mowing is relatively              at removing nitrogen from groundwater supplies,
          easy, and the clippings can be readily collected for a       except in poorly drained areas where groundwater
          more permanent removal of nitrogen and other                 remains near surface soils. Areas with a deep water
          pollutants from the buffer area. Considering that            table will need to rely on deep-rooted species to
          grasses - particularly thickly growing covers -              realize any nitrate removal prior to recharge from
          are also effective at reducing runoff velocity, they         groundwater supplies to nearby waterways.
          may be used with the additional effect of promoting              There is considerable variation in the docu-
          slow, shallow sheet flow of runoff into a naturally          mented nitrate-reducing capacity of forested buffers,
          wooded buffer area. Although grasses are effective           'depending on site and climate. Whole-watershed
          as vegetated buffer species, they lack the versatility       studies conducted by Peterjohn and Correll (1984)
          required of multiple-use buffers - for preserving            and Lowrance et al. (1984a,b) report high levels of
          wildlife habitat or promoting visual diversity, for          nitrate removal from surface water within forested
          instance - and generally are not suitable for use as         buffers of mid-Atlantic latitudes, while work con-
          the only cover within a multiple-use vegetated               ducted by Warwick and Hill (1988) noted very little
          buffer area. Grasses therefore are suitable as part of       nitrate removal in.northem latitudes (Canada).
          the vegetated matrix that makes up the buffer area,          Warwick and Hill (1988), however, did note that
          or as ground cover in the area immediately preced-           reduced nitrate removal at their study site may have
          ing the naturally vegetated buffer.                          been-at least partially due to minimal retention time
                                                                       of runoff during their experiments, and that in-
              -Woody-stemmed Species                                   creased retention time of runoff water in a forested
              Woody-stemmed species generally have deeper              buffer should increase nitrate removal efficiency.
          and more well-developed root systems than grasses,               Groffman et al. (1992) and Simmons et al.
          and when the root system is greater than t  wo feet          (1992), in companion studies, noted that nitrate-
          deep, the vegetated buffer may be effective for the          nitrogen reduction in a vegetated buffer is domi-

          18









           nated by plant uptake during the growing season,              in buffer management schemes. The removal of leaf
           but that soil microbial denitrification is the domi-          litter, however, results in the loss of organic/detrital
           nant nitrate removal mechanism during the dormant             material to soils in the vegetated buffer, changing
           season. Denitrification during the dormant season             one of the conditions - high organic content -
           was a result of a higher seasonal water table that            that promotes the growth of denitrifying microbial
           allowed nitrate-laden waters to remain near surface           communities. The positive or negative effects of leaf
           soils, which are richer in organic content and allow          litter removal may be site-specific (e.g., presence of
           for microbial denitrification. Groffman et al.                a high water table).
           (1991b) reported that nitrate removal decreased by
           64 percent between the growing and dormant                    Buffer Width
           seasons in their study of vegetated buffers in Rhode              Buffer width variability is one of the most
           Island, while Correll et al. (1992), during a study of        versatile tools available to the resource manger.
           vegetated buffers in Maryland, reported 97 percent            Other variables that affect the efficience of veg-
           nitrate removal rates from groundwater in the fall            etated buffers in the removal of pollutants are often
           @growing season), declining to 81 percent removal             unchangeable, or at least may not be altered in a
           in winter months (dormant season).                            very cost-effective manner. Buffer width, however,
               These findings suggest that, at least in temperate        is often easy to manipulate in order to better achieve
           latitudes, seasonal variability in vegetated buffers          the desired affect (e.g., water quality protection).
           can be expected. Actively growing vegetation will                 Table 3 lists vegetated buffer widths reported in
           be effective at nutrient removal during summer                the literature to be adequate for generalized purposes.
           months, when coastal waters are typically most sus-               The range of buffer widths runs from two
           ceptible to nutrient inputs. During the dormant               meters to nearly 200 meters, with a variety of
           season of vegetation, at least in areas where ground-         vegetation types reported. These data are presented
           water can rise near the soil surface, denitrification         graphically in Figure 3, showing the overall range of
           will continue to remove nitrate, but possibly at a re-        values reported to be adequate to protect water
           duced rate. Cold weather months, however, may                 quality in several categories of water bodies. The
           result in vegetated buffers becoming ineffective as the       values contained in the table and figure suggest that
           ground freezes and becomes generally impermeable.             even relatively narrow buffers (less than 10 meters
               Although not as simple as mowing the grass, se-           wide) have some reported value as a resource
           lective harvesting of woody-stemmed species is pos-           mangement tool for the protection of water quality.
           sible, thereby permanently removing nutrients from            Based upon mean values reported by category,
           the vegetated buffer system (Lance,1972; Leak and             however, forty-five meter buffers appear adequate to
           Martin, 1975; Todd et al., 1983; Lowrance et al.,             protect water quality in general, at least within
           1984c; Ehrenfeld, 1987). Should a vegetated buffer            freshwater systems and areas where sediment and
           not be periodically harvested, eventually the nitro-          adsorbed pollutants are the major concern.
           gen stored in plant tissues will reenter the system               Table 4 presents a range of pollutant removal
           through decomposition. Woody-stemmed species                  effectiveness values, according to buffer width,
           are good long-term nitrogen sinks, but removal of             reported in the literature. Although values for the
           the entire plant also removes the nitrogen uptake             removal of other pollutants may have been given in
           and storage mechanism. As trees are removed from              the publications cited, those presented in Table 4
           the buffer area, they will need to be replaced for con-       sediment, total suspended solids (TSS), nitrogen,
           tinued nutrient removal at a more or less steady rate.        nitrate, and phosphorus - were reported most
               Ehrenfeld (1987) noted that most primary                  frequently, and were felt to provide the best range of
           production by trees is converted to leaf materials,           values for review purposes. Also provided in the
           and Peterjohn and Correll (1984) found that 81                table, when given in the original manuscript, is
           percent of the nitrogen uptake in a riparian buffer           information on runoff (pollutant) source, vegetation
           was returned to the forest floor as leaf litter at the        type(s), and slope of the buffer.
           end of the growing season. Removal of leaf litter                 What is immediately obvious is the variability
           from vegetated buffers may therefore be considered            in pollutant removal over both the range of buffer
           an effective permanent nitrogen removal mechanism             widths and within similar buffer widths surnmerized

                                                                                                                                 19











                 Table 3.- Recommended vegetated buffer widths for pollutant removal, giving the desired effect of the implemented
                 buffer. The reported values are generally intended, as minimum buffer width values to achieve the desired purpose. [I meter
                 3.28 feet]



                                Author(s),              Width (m)                        Objective                                    Specifics
                      in: Comerford et all 1992               2             Maintain stream channel stability                        Ozark Mts
                      Ahola, 1990                          2-10                  Stream habitat protection
                      Ahola, 1990                          5-20                     River/lake protection '
                      Scheuler and Bley, 1987                 7                Low level pollutant removal                         Grassed buffer
                      in: Comerford et al., 1992           7-12                     General purpose use                         Low slope; rural land
                      Palmstr6m, 1991                         7.6     1             General purpose use
                      Doyle et al., 1975                      7.6       Protect water quality from animal wastes                   Forested buffer
                      in: Comerford et al., 1992              8                Protect general water quality
                      in: Comerford et al., 1992              9         Protect water quality from ground-based
                                                                                    herbicide applications
                      Martin et al., 1985                     10 -         Protect water quality from clear-cut                    Forested buffer
                      Clark, 1977                             10                    General  purpose use                  0% slope over slightly erodible
                                                                      I                                                                  soils
                      Swift, 1986                          10-19               Protect general water quality                    Road runoff sediment
                      Trimble & Sartz, 1957              10.6-12.2         Protect water quality from logging                        <10% slope
                      Florida Div. Forestry, 1990             11               Protect general water quality                    Primarily strearnside
                      in: Comerford et al., 1992              11           Protect small stream water quality                      Forested buffer
                      in: Comerford et al., 1992           12-24               Protect general water quality                       Forested buffer
                      in: Comerford et al., 1992           12-83               Moderate erosion protection                            Forested
                      in : Comerford et al., 1992-            15           Protect water quality from pesticides
                      Phillips, 1989b                      15-60               Protect general water quality                     Well-drained soils
                      in: Comerford et al., 1992           15-103                Severe erosion protection                         Forested buffer
                      Corbett & Lynch, 1985                20-30           Protect water quality from logging                      Forested buffer
                      Clark, 1977                             23           Protect water quality from logging                      Forested buffer
                      Moring, 1982                            30               Protect salmon egg and juvenile                     Forested buffer
                                                                                       development
                      En-nan et al., 1977                     30       Protect stream water quality from logging                   Forested buffer
                      USACE, 1991                             30                    90%-removal of TSS                             Grassed buffer
                      in: Comerford et al., 1992              30       Protect water quality from aerial herbicide,
                                                                                        applications
                      in: Comerford et al., 1992              31        Protect large stream/river water quality                   Forested buffer
                      Phillips, 1989b                      40-80               Protect general water quality                    Poorly drained soils
                      Clark, 1977                             45               Protect general water quality             30% slope over severely erodible
                                                                                                                                         soils
                      Clark, 1977                             46               Protect general water quality
                      in: Comerford et al., 1992              91           Protect private residences from aerial
                                                                                    herbicide applications
                      Phillips, 1989b                         93               Protect stream water quality                     Under all conditions
                      Roman & Good, 1983                      100                   Wetland protection                          NJ Pinelands habitat
                      Brown et al., 1990                      178              Protect wetland water qu'ality













                20










              in Table 4. This variability in vegetated buffer pol-                    sources with differing input concentrations (see
              lutant removal effectiveness is a direct result of the                   Table 4). The relationships between percent removal
              site-specific conditions previously discussed. Most                      and vegetated buffer width given here, therefore,
              of the reported pollutant removal values come from                       integrate buffer effectiveness over a range provided
              studies that have utilized buffers vegetated with                        in the literature, and are to be interpreted as general-
              grasses to treat runoff from sources rich in pollu-                      ized, or average, pollutant removal effectiveness.
              tants - manure, sewage spray, and feedlots for in-
              stance. The range of values for removal effectiveness                         Removal of sediment and suspended solids
              presented in Table 4 may therefore be biased toward                           Sediments are readily removed from surface
              the treatment of extreme pollution sources, compared                     water runoff moving through vegetated buffers. This
              to what may be considered typical for runoff water.                      is evident from Table 4 and is further exemplified in
              Furthermore, studies of grassed buffers have provided                    Figure 4, which shows that removal efficiencies are
              most of the data summarized in Table 4, with the result                  typically high, even for relatively narrow vegetated
              that forested buffers are potentially underrepresented                   buffers. From the modeled relationship, a vegetated
              with regard to pollutant removal efficiency.                             buffer of even two meters in width could be ex-
                   The data presented in Table 4 are graphically                       pected to remove about sixty percent of the sedi-
              shown in Figure 4 through Figure 8 for sediments,                        ment load entering the vegetated buffer. A twenty-
              total suspended solids, nitrogen, nitrate, and phos-                     five-meter-wide vegetated buffer could be expected
              phorus. An associated "best fit" curve - a logarith-                     to remove about eighty percent of sediment inputs.
              mic function using percent removal as the depen-                         Only slight increases in removal efficiency with
              dent variable - is also provided to show the mod-                        increasing buffer width are noted for buffers greater
              eled relationship between buffer width and pollutant                     than 25 meters wide. Overall, vegetated buffer
              removal efficiency. The relationship between buffer                      width must increase by a factor of 3.5 in order to
              width and polutant removal agrees with those                             achieve a 10 percent increase in the removal of
              previously developed by Karr and Schlosser (1978),                       sediment in the vegetated buffer. Although the
              Wong and McCuen (1982), and others, in which                             majority of data that was used to develop the curve
              removal efficiency increases rapidly up to a certain                     shown in Figure 4 comes from grassed buffers, the
              buffer width, after which large increases in buffer                      few reported values that come from forested buffers
              width are needed to improve removal efficiency by                        are high, particularly at larger buffer widths.
              even a small amount. It is important to note that the                         The pattern noted for the removal of total
              data used to construct the graphs in Figures 4                           suspended solids JSS; Figure 5, following page) in
              through 8 do not come from a single, controlled                          vegetated buffers is similar to the relationship seen
              study, but from a wide variety of studies reported in                    for the removal of sediment. In vegetated buffers six
              the literature. The studies were conducted at a                          meters in width, the expected removal efficiency for
              variety of sites and treated different pollutant                         TSS is about sixty percent. Eighty percent removal
                 igure 3

                   Figure 3. A range of vegetated
                   buffer widths reported in the
                   literature to be adequate for the         Rivers and Lakes                         N=3
                   protection of water quality in
                   various water body types. The range
                   represents buffer widths noted in the
                   literature, as reported in Table 3. The             Stream                                                                     N=7
                   General category contains buffer
                   widths that were reported to protect
                   water quality, but were not specific to             General                                   N= 13
                   a type of water body. The heavy line
                   contained in the bar represents the
                   mean of the data that make up the                             0   10     20     30     40     50     60      70     80     90      100
                   range. [I meter = 3.28 feet]                                                             Buffer Width (m)



                                                                                                                                                          21











                Table 4. A summary of pollutant removal effectiveness values according to width of the vegetated buffer. Removal
                efficiency values are given as percen            't removal for each of the various pollutants treated in the vegetated buffer                          sediment,
                TSS, total nitrogen, total phosphorus, and nitrate-nitrogen. [I meter = 3.28 feet]

                                                                                                       PollutantRemoval
                                               Author(s)                 Width (m) Sediment                 TSS              N             P             N03
                                   Doyle et al., 1977                         0.5                                                          9VO           00/0-
                                   Neibling, & Alberts,        1979           0.6           91%
                                   Neibling & Alberts,         1979           0.6           37%
                                   Neibling & Alberts,         1979           12            78%
                                   Doyle et al., 1977                         1-5                                                          8%            57%
                                   Neibling & Alberts,         1979           2.4           82%
                                   Doyle et al., 1975                         3.8                                          95%             99%
                                   Doyle et al., 1977                         4.0                                                          62%           68%
                                   Young et al., 1980                         4.06                                         84%             83%           9170
                                   Dillaha et al., 1988                       4.6                           31%            070             2%
                                   Dillaha et al., 1988                       4.6                           87%            61%             63%
                                   Dillaha et al., 1988                       4.6                           76%            67%             52%           3%
                                   Magette et al., 1987                       4.6                           72%      1     17%             41%
                                   Dillaha et al., 1986b                      4.6           63%                            63%             63%
                                   Neibling & Alberts,         1979           4.9           83%
                                       bling & Alberts,        1979           6.1           90%
                                   Doyle et al., 1975                         7.6                                          96%             99%
                                   Schellinger & Clausen, 1992                7.6                           401b           15%             601o
                                   Schellinger & Clausen, 1992                7.6                           27%      1     16%             18%
                                   Dillaba et al., 1988                       9.1                           58%            7%              19%
                                   Dillaha et al., 1988                       9.1                           95%            77%             80%           401o
                                   Dillaha et al., 1988                       9.1                           88%            71%             57%           17%
                                   Dillaha et al., 1986b                      9.1           78%                            78%             78%
                                   Magette et al., 1987                       92                            86%            51%             53%
                                   Thompson et al., 1978                      12                                           45%             55%           46%
                                   Bingham et al., 1978                       13                                           28%             25%           28%
                                   Mannering & Johnson, 1974                  15            45%
                                   Doyle et al., 1977                         15.2                                         97%             99%
                                   Lake & Morrison, 1977                      15.2          46%.
                                   Peterjohn & Correll, 1984                  19            90%,                           62%             OVO           60%
                                   Young et al., 1980                         21.3          81%
                                   Young et al., 1980                         21.3          75%
                                   Schwer & Clausen, 1989                     26                            95%      1     92%             89%
                                   Young et al., 1980                         27.4          93%
                                   Young et al., 1980                         27.4                          66%            87%             88%
                                   Young et al., 1980                         27.4                          82%            84%             81%
                                   Edwards et al., 1983                       30                            23%            31%             29%
                                   Doyle et al., 1975                         30.5                                         98%             99%
                                   Patterson et al., 1977                     35                            71%
                                   Thompson et al., 1978                      36                                           69%.            61%           62%
                                   W-ong & McCuen, 1982                       45            90%
                                   Woodard, 1988                              57            99%
                                   Edwards et al., 1983                       60                            87%            83%             84%
                                   Baker & Young, 1984                        79                      1                    99%
                                   Kaff & Schlosser, 1978                     91            55%       1     50%                            -
                                   Karr & Schlosser, 1978                     215          97.5%            90%
                                   Karr & Schlosser, 1978                                   99C/O           97%
                                   Lowrance et al., 1984                                                                   85%         30-42%      8 '30/b
                                   Jacobs & Gillam, 1985                                                                                                 99%
                                   Rhodes at al., 1985                                                                                                   99%
                                                                                                      @
                                                                                                            95
                                                                                                            '8


                                                                                                            86












                                                                                                            950/o


                                                                                                            66
                                                                                                            82   0
                                                                                                             0
                                                                                                      23E
















                                   Reuter et al., 1992                                                      85%                            97%         85-90%
                                   Schipper et al., 1989                                                                                                 98%



               22











                  Table 4. A summary of pollutant removal effectiveness values according to width of the vegetated buffer.
                  Continued


                                            Runoff source                 Vegetation               Slope                                Other
                                            Dairy manure                  Grass-fescue               10%                              90 mT/ha.
                                              Bare soil                        Grass                 701o                 For coarse-grained sediments
                                              Bare soil                        Grass                 7%                      For clay-sized particles
                                              Bare soil                        Grass                 7%                      For clay-sized particles
                                            Dairy manure                       Grass                                                  90 mT/ha
                                              Bare soil                        Grass                 7%                      For clay-sized particles
                                            Dairy manure                  Forest/scrub             35-40%                    Gravely, silt-loam soils
                                            Dairy manure                       Grass
                                            Dairy feedlot                                            401o
                                            Dairy manure                  Orchard grass              501b                       Concentrated flow
                                            Dairy manure                  Orchard grass              11%              Av. 10,000 kg/ha manure application
                                            Dairy manure                  Orchard grass              16%              Av. 10,000 kg/ha manure application
                                            Dairy manure                  Forest/scrub             35-40%                    Gravely, silt-loam soils
                                            Fertilized cropland           Orchard grass
                                              Bare soil                        Grass               _71/_0                    For clay-sized particles
                                              Bare soil                        Grass                 791,                    For clay-sized particles

                                     -Dairy yard runoff                Fescue & rye mix              201o                Poorly drained, surface sample
                                            Dairy yard runoff          Fescue & rye mix              2%                Poorly drained, subsurface sample
                                            Dairy manure                  Orchard grass              501o                       Concentrated flow
                                            Dairy manure                  Orchard grass              11%              Av. 10,000 kg/ha manure application
                                            Dairy manure                  Orchard grass              16%              Av. 10,000 kg/ha manure application



                                            Dairy manure                  Orchard grass
                                            Poultry manure                     Fescue                6-8%
                                                                          Bluegrass sod
                                            Dairy manure                  Forest/scrub             35-40%              90 mT/ha; Gravely, silt-loam soils
                                                                          Bluegrass sod
                                            Agricultural runoff             Forested
                                            Feedlot runoff                     Corn                  401o
                                                                               Oats                  401o
                                            Milk house waste           Fescue & rye mix              2%
                                                                               Corn                  401o              25-year, 24-hour storm simulation
                                                                          Orchard grass              401o              25-year, 24-hour storm simulation
                                                                          Sorghum/grass              401o              25-year, 24-hour storm simulation
                                            Feedlot runoTf                     Fescue                201o         Settling basin, then through 60 m of grass
                                                                                                                                        buffer
                                            Dairy manure                  Forest/scrub             35-40%                    Gravely, silt-loam soils
                                            Liquid dairy waste                 Fescue                3.4%



                                                                          Natural, mixed
                                            Feedlot effluent                   Fescue                201o           Moved through 2 consecutive 30m VFS
                                             Fertilizers                       Grass
                                                                          Bermuda grass



                                                                            Forested
                                                                          Forest/wetland                                  79.6 ha undisturbed watershed


                                            Fertilized field           Man-made gravel
                                                 runoff
                                            Sewage spray                  Forested pine


                                                                                                                                                                                         23










           occurs at about sixty meters of buffer width, beyond        -buffer width and nitrate removal is simply inappro-
           which improved removal efficiency is slight with            priate. Considering that nitrate removal predomi-
           increased buffer width. For TSS removal, an ap-             nantly occurs through biological rather than physi-
           proximate increase in buffer width by a factor of 3.0       cal or chemical means., site-specific variables, such
           provides a 10 percent increase in removal efficiency.       as denitrification potential, may need to be consid-
           The greater vegetated buffer widths required for            ered in order to better estimate nitrate removal in
           TSS removal, compared to sediment removal, may              vegetated buffers.
           be due to smaller-sized particles and a greater
           amount of particulate matter, which in general                  Removal of total phosphorus
           requires greater buffer width to b e adequately                 The data given in Table 4 and modeled in Figure
           removed from surface water runoff. As with sedi-            8 suggest that the removal efficiency of phosphorus
           ment removal, the few included forested buffer              in vegetated buffers is quite variable, and relatively
           values are high for the removal of TSS from runoff.         low at very narrow buffer widths. Buffer efficiency
                                                                       increases rapidly to twelve meters of buffer width,
               Removal of total and nitrate-nitrogen                   where approximately sixty percent phosphorus
               The removal efficiency of vegetated buffers for         removal is achieved. Buffer efficiency improves
           nitrogen varies considerably, particularly within the       with added buffer width, until approximately eighty
           range of narrow buffer widths. This is very evident         percent removal is achieved in an eighty-five-meter-
           from both Table 4 and Figure 6. Removal efficiency          wide vegetated buffer. Greater phosphorus removal,
           of nitrogen in a nine-rrieter-wide vegetated buffer         as with other pollutants, is achieved only with large
           is expected, from the modeled relationship, to be           additions of buffer width after this point. Overall, an
           about sixty percent. Removal efficiency increases           approximate increase in buffer width by a factor of
           with increasing buffer width to about 80 percent            2.5 is required to achieve a 10 percent increase in
           removal at sixty meters of buffer width, after which        phosphorus removal.
           point the rate of removal of nitrogen per unit in-              Although phosphorus is reported to be typically
           crease in buffer width slows. An approximate                bound to sediments, it is generally bound to smaller-
           increase in vegetated buffer width by a factor of 2.6       sized sediment particles (Karr and Schlosser, 1977).
           is required to achieve a 10 percent inc rease in            Since smaller-sized particles and particulates are
           nitrogen re m-oval efficiency.                              typically not as effectively filtered out by vegetated
               The nitrogen removal efficiency data used in            buffers as coarse-grained sediments, this may result
           Table 4 and Figure 6 are mainly from studies.               in the differences noted'between sediment and
           performed in grassed buffers, and therefore may not         phosphorus removal efficiencies, as seen when
           adequately portray removal efficiencies of forested         comparing the removal patterns in Figure 4 and
           buffers. However, the scatter in the forested buffer        Figure 8. The forested buffer data given in Figure 8
           data included in Figure 6 appears as wide and as            appear to be as variable and scattered as those for
           variable as that noted for grassed buffers.                 grassed buffers.
               Nitrate removal, is variable, but generally low,
           according to'the data give ni in Table 4 and shown in           Performance standards
           Figure 7, for all buffer widths. The modeled nitrate            From the values given in Table 4, and the
           removal-to-buffer width relationship shown in               modeled relationships seen in Figure 4 through
           Figure 7 suggests that approximately 50 percent of          Figure 8, an estimated removal standards matrix
           the nitrate present will be removed in buffers of one       was constructed (Table 5). Other than for nitrate, the
           hundred meters in width. The modeled relationship           matrix suggests that, on average, 50 percent overall
           for nitrate'removal suggests that increased removal         pollutant removal can be expected to occur in
           will only occur given enormous increases in veg-            vegetated buffers five meters wide. Seventy percent
           etated buffer width. It is unclear if the low removal       removal efficiency can generally be expected to oc-
           efficiency of nitrate in vegetated buffers provided         cur in vegetated buffers of about thirty-five meters
           by this model is due to the data being generally            in width, while eighty percent removal efficiency
           from grassed buffers, which are often less than ideal       might b e expected in buffers of about eighty-five
           denitrification sites, or if the relationship between       meters in width. Vegetated buffer widths between

           24










                   Figure 4.




                            Figure 4. Relationship of percent                               100-                0
                            removal to buffer width for the                                       -0  00
                            treatment of sediments contained in                                80- P
                            surface water runoff. An approximate                           >           0
                                                                                           0
                            increase in vegetated buffer width by a                        E
                                                                                           4)  60-
                            factor of 3.5 is required to achieve a 10
                            percent improvement in removal of
                                                                                           E   40-
                            sediment. The most efficient vegetated
                            buffers, based upon width-to-removal
                            ratios, will be about 25 meters in width,                      0-0 20-
                            after which large additions of buffer                                 -                                                                 N = 4 (forested) 0
                            width are required to achieve only small                                                                                                N = 15 (grassed) 0
                            increases in sediment removal efficiency.                          0                                                                     1               1
                                                                                                  0           50           100           150          200           250            300
                            The modeled line is: % removal = [(7.613                                                              Buffer Width (m)
                            * In(width in meters)) + 55.8]. Data are
                            taken from Table 4. [1 meter = 3.28 feet]






                   Figure 5.




                            Figure 5. Relationship of percent                                  100-
                            removal to buffer width for the treat-                                                                                                                   0
                            ment of TSS contained in surface water                                'as
                            runoff. An approximate increase in                                 80-
                            vegetated buffer width by a factor of 3.01 is                  >
                                                                                           0
                            required to achieve a 10 percent improve-                      E   60- 0
                            ment in removal of TSS. The most efficient
                            vegetated buffers, based upon width-to-                            40-
                            removal ratios, will be about 60 meters in                     -IR    -0
                            width, after which large additions of buffer                       20-   0
                            width are required to achieve only small                                                                                                 N = 3 (forested) 0
                            increases in TSS removal efficiency. The                                 0                                                               N = 15 (grassed) 9
                            modeled line is: % removal = [(8.34 *                               04 .    1.111-1111                         1    1 1 1 1    1 1        1 1 1 1        1
                            In(width in meters)) + 45. 1 ]. Data are                              0            50           100           150          200           250           300
                            taken from Table 4. [1 meter             3.28 feet]                                                    Buffer Width (m)









                                                                                                                                                                                         25










           250 and 550 meters will be needed to achieve 90 -                   Decreased disturbance from neighboring
           99 percent overall pollutant removal effectiveness.                   areas
               The matrix given in Table 5 may be useful in                    Decreased predation: wider buffers further
           estimating the potential overall removal of a veg-                    reduce predation
           etated'buffer for a given buffer width, or for estimat-
           ing the removal of a given buffer width for a spe-                It is difficult to be specific about the value to
           cific pollutant of concern. These values should be            wildlife of vegetated buffers as habitat, since the
           held in light of the site-specific conditions in and          vegetative makeup of the buffer area will often
           around the actual buffer area, and buffer width               determine what species will use it, as well as how
           adjusted according to best professional judgment for          they use it. The habitat value of vegetated buffers
           best estimating a buffer width to achieve the desired         for different animal and plant species will also be
           removal efficiency.                                           determined by width of the buffer, proximity to
                                                                         other required habitat types, proximity and density
               M Wildlife Habitat Protection                             of predators and competitors, and proximity of each
               For the purposes of this review, the term "wild-          organism to others of its species. Furthermore, noise
           life" refers to both animal and plant species. The use        disturbance from developed or developing areas
           of the term wildlife, with regard to its animal               affects habitat quality and use. The greater the
           component, is generally meant to encompass all                disturbance, the greater the buffer required to reduce
           except large mammals. This is particularly. true at           the impact upon the use of adjacent environments
           narrow buffer widths, but large mammals may                   by wildlife. In some instances, buffers may need to
           become part of the vegetated buffer complex as the            be established around habitat areas in order for them
           width of the buffer increases,. providing more                to be successfully utilized by wildlife. This will be
           suitable conditions and space for large mammals.              most critical in areas that are highly developed and
               The vegetated buffer concept has reached its              create a lot of disturbance     noise, for instance.
           greatest application for wildlife habitat protection in       The value of narrow buffers as habitat will therefore
           the development of "gre* enway   ... .. stream corridor,"     be directly related to the amount of disturbance they
           and "habitat corridor" management programs. These             receive from adjacent areas.
           practices generally set aside vegetated strips along              Table 6 provides a summary of buffer widths
           rivers and streams to promote good water quality,             reported in the literature considered to provide
           maintain wildlife habitat, and provide wildlife travel        habitat for various broad wildlife categories: this
           corridors. Current paradigms suggest that increased           summary is presented graphically in Figure 9.
           environmental diversity and complexity promote                Several authors (for example, Tassone, 198 1; Cross,
           increased biodiversity (see Wilson, 1988). There-             1985; Triquet et al., 1990; Groffman et al., 1991b)
           fore, the establishment of vegetated buffers can be           note that vegetated buffers that are contiguous to
           viewed as one step in maintaining local ecosystems            areas of natural vegetation are likely to support, or
           and promoting regional biodiversity. The following            be used by, a greater number of species. Even sinall
           highlights some of the potential benefits to wildlife         vegetated buffers can be enhanced in value by being
           of vegetated buffers, as.noted by Groffman et al.             close to undisturbed areas that more fully satisfy
           (1991b):        -                                             species-specific resource requirements.'
               - Increased species diversity: mixed habitat                  From the reported values in Table 6, which
                    types promote greater diversity                      range from 15 to 200 meters, it is difficult to deter-
               - Increased foraging sites; mixed vegetation              mine a "best size" buffer width for general wildlife
                    provides greater food availability                   habitat. It has been noted that 15-meter buffer
               - Wildlife dispersal corridor: wider buffers              widths provide habitat under certain conditions, and
                  @ provide a better travel corridor                     it may be that widths much less than that will not
               - Escape from flooding                                    provide adequate space - bird nesting sites for
               - Hibernation sites                                       instance - for resident species. Buffers less than 15
               - Breeding and nesting sites: wider buffers               meters  wide, however, may provide adequate habitat
                    reduce nest parasitism                               for the temporary activities, such as resting'or
                                                                         feeding, of both resident and transitory' species.

           26










               Figure 6.



                    Figure 6. Relationship of percent removal                 loo- 0   0    0          0                                    0
                    to buffer width for the treatment of nitro-                                     0
                    gen contained in surface water runoff.
                    An approximate increase in vegetated buffer            >
                                                                           0
                    width by a factor of 2.6 is required to achieve        S                   0
                                                                           0  60-
                    a 10 percent improvement in removal of
                    nitrogen. The most efficient vegetated buffers,        401,
                                                                           2  40-
                    based upon width-to-removal ratios, will be
                    about 60 meters in width, after which large            z
                    additions of buffer width are required to                 20-   00
                                                                                  -                                                     N 5 (forested) 0
                    achieve only small increases in nitrogen                            0                                               14=211,ra, I!,
                    removal efficiency. The modeled line is: %                 0111, - II                                               "@ _4,
                    removal = [(10.5 * ln(width in meters)) +                     0     110 .... 210 .... 310 .... 510       610     710    80
                    37.4]. Data are taken from Table 4.                                                     Buffer Width (m)
                    [I meter = 3.28 feet]







               Figure 7.



                    Figure 7. Relationship of percent                         100-
                    removal to buffer width for the treat-
                    ment of nitrate contained in surface
                    water runoff. Unlike the other modeled                    80-
                    pollutant removal-to-buffer width relation-            0
                                                                           E  60-                          0
                    ships, that for nitrate is suggested to be
                    inappropriate. Nitrate is typically removed
                    by biological processes rather than                       40-
                    through physical and chemical means, and
                    the variables that control denitrification                20
                    may better determine the removal of                                                                                 N = 1 (forested) 0
                    nitrate in vegetated buffers than does                                                                              N = 10 (grassed) 0
                    buffer width. Data are taken from Table 4.                0    . . . I I I I I I                      IT . . . IT." I      I
                    [I meter = 3.28 feet]                                         0    5      10    15      20    25     30     35      40    45     50
                                                                                                            Buffer Width (m)



















                                                                                                                                                       27










          Figure 8.


              Figure 8. Relationship of percent removal    100- 0 0   0        0
              to buffer width for the treatment of
              phosphorus contained in surface water
                                                           80-
              runoff. An approximate increase in vegetated0
              buffer width by a factor of 2.5 is required toE
                                                           60-
              achieve a 10 percent improvement in removal 9)
                                                         a.   -
              of phosphorus. The most efficient vegetated0
              buffers, based upon width-to-removal ratios, CL 40-0
                                                         0
                                                         0
              will be be about 75 meters in width, after
              which large additions of buffer width are    20-
              required to achieve only small increases in     - b                                      N 5 (forested) 0
                                                                                                       N 11 (,@sd"
              phosphorus -removal efficiency. The modeled   0 41                                       ""    ,
              line is: % removal = [(10.3 * ln(width in       0    10   20     30   40   50     60    710  80    90
              meters)) + 34. 1 ]. Data are taken from Table 4.                    Buffer Width (m)
              [1 meter 3.28 feet]








         Table 5. Estimated removal standards matrix for specific pollutants as taken from the modeled relationships shown in
         Figure 4 through Figure 8 for vegetated buffers. In general, greater than 50 percent removal standards can be met with
         vegetated buffers about 5 meters wide. The 80 percent removal category generally marks the optimal width-to-removal ratio
         boundary, above which the increase in removal efficiency for a given increase in buffer width is small. [I meter 3.28 feet]



                                                          Buffer Width (m)
                       % Removal     Sediment        TSS      Nitrogen       Nitrate      Phosphorus
                          50            0.5          2          3.5            >100            5
                          60            2            6          9               -              12
                          70            7            2D         23              -              35
                          8D            25           6D         6D              -              85
                          90            90           200        150             -             250
                          99-           300          700       350              -             550
                                                              @0_








         28










                Many studies have determined buffer widths for           rather than providing a sharp contrast between
            wildlife habitat by determining species-specific             habitat types. In some cases where no buffer exists,
            needs - such as those for rare, threatened, or               a sharp contrast may be unavoidable, and transient
            endangered species - and then applying them to               wildlife may be the major users of the vegetated
            buffer width requirements. Few studies, however,             buffer area. Wider buffers will provide less contrast,
            have determined overall needs for multiple-species           since they will produce a larger gradient between
            use of buffers, and fewer still have studied use             habitats, and will become habitat themselves. Some
            patterns of wildlife for existing or newly established       routine assessment and maintenance practices may
            vegetated buffers that are part of a multiple-use            be required to maintain habitat value and keep in-
            resource management program. It is therefore                 vading species from overtaking implemented buffers.
            difficult to determine how buffers of various widths
            and vegetative makeup, once implemented, will be                 0 Erosion and Flood Control
            used by wildlife.                                                Vegetated buffers employed as erosion controls
                However, if current paradigms are correct, then          are generally applied as best management practices
            with regard to value of vegetated buffers to wildlife,       to mitigate the off-site impacts of development and
            bigger is better, and some is better than none. Large        construction activities. However, by their very
            buffers may be required in areas where species               nature, vegetated buffers can assist in reducing
            preservation is a major focus of vegetated buffer            erosion even when not specifically designed for that
            development, while smaller buffers may be ad-                purpose. Since vegetated buffers slow the velocity
            equate in other areas, particularly where more               of runoff flow, as well as dissipate flow and reduce
            contiguous stretches of habitat are nearby. Larger           channelized flow, they will reduce the probability of
            buffers will provide a greater diversity of resources        erosional problems downstream of buffer areas.
            over the long term for wildlife in general, while                It was previously noted, however, that vegetated
            small patches will provide "island" habitats in the          buffers can become clogged with sediment removed
            larger mosaic. The greater the diversity of available        from surface water runoff. Vegetated buffers that are
            resources, the greater the potential for the long-term       employed specifically for erosion control - for
            survival of the targeted or intended wildlife species,       instance, to control sediment movement from
            as well as for incidental users.                             construction sites - may need to be rehabilitated
                Some caution, however, is noted in a summary             after construction work if they are intended to
            by Groffman et al. (1991b) of vegetated buffers as           continue functioning as a multiple-use buffer.
            wildlife habitat. The authors note that sharp con-               Vegetated buffers also have value for flood
            trasts between habitat types, such as engineered             control, and have been employed for this purpose.
            buffers, may promote the growth of weed species.             They control flooding by reducing flow velocity,
            The weed species could invade nearby natural areas,          allowing absorption and storage of water in soils,
            replacing resident vegetation with opportunistic and         and by moving water from surface to subsurface
            transient species. This was reported by Dillaha et al.       watercourses. Vegetated buffers also mitigate
            (1986a) to be a common problem in vegetated                  property destruction by maintaining some undevel-
            buffers assessed in the state of Virginia. Weed              oped land along waterways and keeping developed
            species have been known to invade nearby habitats,           or developing areas back from floodwaters, storm
            thereby reducing the habitat value of the buffer. This       surges, and extreme high tides.
            is a most important consideration if the vegetated               The capacity of the buffer area to provide flood
            buffer is established for the protection of rare,            control will depend on rainfall and runoff intensity,
            threatened, or endangered species, and may also be           soil characteristics, hydrologic regime, and slope of
            a consideration in the development of small buffers          both the buffer and the source of runoff water. Even
            that represent island patches.                               under ideal conditions, the ability of a vegetated
                This suggests that care should be taken in               buffer to control flooding will be related to the
            designing and designating vegetated buffers next to          water source area. A buffer that is small relative to
            sensitive areas, or where rare or endangered species         the water source area will have only limited ability
            live. In these cases, the vegetated buffers could be         to control flooding. When buffers are applied with a
            developed to graduate into the sensitive habitat,            primary intent of flood control, water-holding

                                                                                                                                29











                 Table 6. Recommended buffer widths for wildlife habitat. The reported widths are generally intended as minimu                                              rn values
                 to provide the desired habitat requirement to meet the given objective. [I meter = 3.28 feet]



                                  Author(s)                  Width W                             Objective                                           Specifics
                             Triquet et al., 1990                15-23                     General avian habitat                              Riparian wooded area
                             Shisler et al., 1987                15-30            Protect wetland habitat from low-                 Densely growing mixed species buffer
                                                                                           intensity disturbances
                                Tassone, 1981                     30                       Wildlife travel corridor
                             Shisler et al., 1987                30-45            Protect wetland habitat from high-                Densely growing mixed species bufTe-r
                                                                                           intensity disturbances
                         Howard and Allen, 1989                   60                       General wildlife habitat
                                Tassone, 1981                     60          Breeding sites for fragment-sensitive bird
                                                                                                   species
                           Groffman et al., 199 1 b             60-100                     General wildlife habitat
                                 Cross, 1985                      67                       Small mammal habitat                               Wooded riparian area
                          Groffman et al., 199 1 b               91.5             Protect significant wildlife habitat                         Natural vegetation
                             Brown et al., 1990                  178                   Wetland habitat protection
                               Scheuler, 1987                    200                  Diverse songbird community
                              U.S. ACE, 1991                    <9W                    For all but large mammals                                  Riparian forest









                Figure 9.


                      Figure 9. Ranges of buffer widths
                      noted in the literature to provide                                      Avian-
                      effective habitat for several broad,                  Wildlife Travel Corridor
                      categories of wildlife. Thexanges                              Breeding Bird -                                           40
                      of categories represented by a circle                            All .Except -
                      arise from one study, and therefore                                                                                                             200---C;-
                                                                                   Large Mammals -
                      may not be very representative of                            General Wildlife
                      that particular category. Two                                                -
                      reported values make up the range                               Rare Species
                      shown by each of the horizontal
                      bars. Data are taken from Table 6.                                            0             20            40             60            80             100
                       H meter       3.28 feet]                                                                                Range of Buffer Widths (m)











                30










            capacity of the buffer area will need to be deter-            general guidelines can be developed for the use of
            mined, and proper width applied to the buffer in              vegetated buffers. Table 7 provides a generalized
            order to store the water received during a given              overview of the pollutant removal effectiveness -
            storm event.                                                  taken from the modeled relationships and as pre-
                                                                          sented in Table 5 - and wildlife habitat value,
                E Historical and Cultural Preservation                    taken from Table 6 - for a range of buffer widths
                While vegetated buffers are best known for their          for multiple-use vegetated buffers. The effectiveness
            use in preserving and protecting water quality and            of vegetated buffers for pollutant removal, as well
            wildlife habitat, application of coastal buffer zones         as for wildlife use, is presented as increasing steps
            may also have value in preserving and protecting              of buffer width.
            historical and cultural sites. In Rhode Island, for               Using the generalized set of buffer widths
            instance, many of the important archaeological sites          presented in Table 7 for developing and implement-
            pertaining to Native Americans         such as summer         ing a vegetated buffer policy requires that local
            encampments and trading sites         are within 200          conditions and intended uses be taken into consider-
            feet of the coast. The same may be true for other             ation. The buffer widths listed in Table 7 are meant
            coastal states. If so, establishing coastal vegetated         to be useful in a general sense for planning pur-
            buffers can preserve potentially important sites for          poses. For example, the table values may be overly
            future archaeological study.                                  large if removal of sediment is the intended effect,
                                                                          and if the area of buffer implementation is very
                N Scenic and Aesthetic Enhancement                        conducive to sediment removal. Similarly, the table
                Aesthetic and scenic qualities of vegetated               values may be too small if the removal of metals is
            buffers often provide an "extra" value or benefit to          the intended effect and the proposed buffer area
            the major purpose for which the vegetated buffer              overlies impermeable soils on steep slopes.
            was designed. As noted in Mann (1975), Simeoni                    From the values presented in Table 7, a mul-
            (1979), and Forman and Godron (1986), landscapes              tiple-use vegetated buffer of five meters could be
            with high visual diversity are generally more ap-             considered a reasonable minimum-buffer-width
            pealing than nondiversified landscapes. Designed              standard. A five-meter-wide vegetated buffer will
            planting of trees and shrubs within the buffer area           provide approximately 50 percent sediment and
            can enhance visual diversity and thus aesthetic               nutrient removal (except for nitrate). While a
            appeal. As the vegetated buffer attracts wildlife,            vegetated buffer of this width may not provide good
            such as songbirds, visual and biological diversity            overall wildlife habitat, it may be sufficient to
            are both enhanced. In areas previously cleared of             provide resting and feeding areas for both resident
            vegetation, reestablishing native species can assist          and migratory species. A five-meter-wide multiple-
            in rebuilding the sense of "wilderness" often associ-         use vegetated buffer can be practically imple-
            ated with coastal expanses. It is this sense of isola-        mented, except in areas of very dense development,
            tion and wilderness that makes coastal regions                and these exceptions could be reviewed as a vari-
            attractive to those who visit.                                ance to general buffer policy. A five-meter-wide
                The aesthetic value of vegetated buffers is, how-         vegetated buffer could be established as a minimum
            ever, mostly based on subjective factors, and there-          goal for the restoration of already developed areas.
            fore not fully transferable in implementation prac-           Establishing a minimum buffer width will also
            tices. Although no criteria for aesthetic values of           maintain or improve the scenic and aesthetic quality
            vegetated buffers exist, aesthetics will continue to be       of the area, and will act as nondestructive, natural
            included as an intrinsic value of vegetated buffers that      fencing between public waters and private uplands.
            are implemented for natural resource management.                  It should be kept in mind, however, that a five-
                                                                          meter-wide vegetated buffer removing approxi-
                0 General Guidelines for Multiple-use                     mately 50 percent of pollutants and sediment
                     Vegetated Buffers                                    contained in surface waters may not meet minimum
                Although the conditions determining the actual            performance standards in all instances. If an ap-
            effectiveness of a multiple-use vegetated buffer will         proximate performance criterion of 80 percent
            be of a local and/or site-specific nature, some               removal is desirable, then a 75-meter-wide ve97

                                                                                                                                   31









           etated buffer may be the acceptable minimum. This             many areas, however, a 25-meter vegetated buffer
           buffer width will also provide minimum general                may make some developable lots unusable due to
           habitat value. If protection of habitat for significant       site constraints, and may not give sensitive re-
           species is to be the main purpose of the vegetated            sources adequate protection. Shifting the fixed
           buffer, then 200 meters may be the minimum accept-            width to higher  or lower values alleviates problems
           able buffer width. This width will also provide               on one end while creating them at the other. This
           approximately 90 percent removal of sediment and              approach has many limitations, but has been used by
           pollutants. As minimum buffer width increases, how-           resource managers in vegetated buffer programs.
           ever, conflict may arise in areas where small-sized               A variation of the fixed-width vegetated buffer
           land parcels or extensive development already exists.         approach is that recommended by the U.S. Forest
               For general-purpose buffers that will provide             Service in a recently published booklet describing
           some value as wildlife habitat, a minimum width of            riparian buffers (see Welsch, 1991). In this case, a
           15 meters is suggested. A vegetated buffer of this            vegetated buffer has a minimum width of 28 meters,
           width should be implementable in most areas that              and consists of three zones. The zone closest to the
           are only moderately developed. Vegetated buffers of           water is of a fixed width (five meters) and allows
           15 meters should provide some water quality                   for no alteration of the buffer. The second, or
           protection for most waterways (e.g., approximately            middle, zone has a minimum width (17       meters) but
           60 percent pollutant removal); will offer minimal             can be expanded based upon local or site-specific
           wildlife habitat value and greater visual and aes-            conditions or to achieve a given effect (e.g., rare
           thetic appeal; and can provide a natural physical             species protection). Limited use, such as selective
           barrier between public and private properties.                'harvest of timber, may be allowed in this zone of the
               For areas that are undeveloped, or are character-         buffer area. The third, or most inland zone, abuts a
           ized by large lot sizes, buffers of 50 meters or more         developed or disturbed area and possesses a mini-
           could be applied to ensure that some areas are                mum width (6 meters) that can also be expanded
           providing general wildlife habitat. Buffers of this           based on local conditions. This inland zone might
           width could be applied to all publicly owned lands,           consist of lawn in a residential setting or hay field in
           such as state parks, recreation areas, and conserva-          an agricultural setting. This approach alleviates some
           tion areas. For areas that are considered critical, or        problems by allowing greater buffer widths to be ap-
           provide habitat for rare, threatened, or endangered           plied as needed, but still may be restricted in its
           species, the buffer width could be extended to 100            applicability in areas where small lot sizes are conunon.
           meters or more to ensure sufficient habitat diversity             A further modification of the fixed-width
           and isolation from disturbance, and to promote the            approach to vegetated buffer implementation is
           long-term survival of these species and their eco-            setting a realistic minimum vegetated buffer width
           system. The minimum acceptable width will be                  based upon lot size or land use. A minimum width
           determined by the function or functions of the vege-          could be established for small lots or high-density
           tated buffer. Resource managers may need to define            residential areas so the buffer will provide some
           present and future uses for the regions under their           benefit for pollutant removal and/or habitat while
           purview, and then develop minimum multiple-use                not inordinately restricting use of property. The
           vegetated buffer widths for the goals and uses desired.       minimum vegetated buffer width could then be
                                                                         expanded as lot size and/or land use changes to
               M Implementation Approaches to Multiple-                  provide greater benefits of pollution removal and
                   use Vegetated Buffer                                  habitat provision, while not overly restricting use of
               One approach to multiple-use buffer implemen-             private or public lands. One example of this ap-
           tation is applying a fixed vegetated buffer width             proach is that developed by the state of Rhode Is-
           along all waterways. For instance, a vegetated                land, which is provided in full detail in Appendix A.
           buffer of 25 meters in width could be required                    An alternative to a fixed-width vegetated buffer
           bordering all waterways. This approach, according             is a vegetated buffer tailored to each site, using a
           to Table 7, would provide approximately 70 percent            model to generate a buffer width based upon a
           overall removal of sediment and pollutants, and               variety of data, but dependent upon site-specific
           provide minimal general wildlife habitat. Along               conditions. This  approach is often data-intensive,

           32










               Table 7. A summary of pollutant removal effectiveness and wildlife habitat value of vegetated buffers according to buffer
               width. The stepwise increments are adapted from Table 5 and Table 6, and reflect changes in pollutant removal effectiveness
               and wildlife habitat value according to width of the vegetated buffer. [ I meter = 3.28 feet]



                   Buffer Width (m)           Pollutant Removal Effectiveness                            Wildlife Habitat Value
                            5            Approximately 50% or greater sediment and          Poor habitat value; useful for temporary activities of
                                                       pollutant removal                                          wildlife
                            10           Approximately 60% or greater sediment a7d-          Minimally protects stream habitat;poor habitat
                                                       pollutant removal                     value; useful for temporary activities of wildlife
                            15                   Greater than 60% sediment and               Minimal general wildlife and avian habitat value
                                                       pollutant removal
                            20           Approximately 70% or greater sediment and          Minimal wildlife habitat value; some value as avian
                                                       pollutant removal                                          habitat
                            30           Approximately 70% or greater sediment and          May have use as a wildlife travel corridor aswell as
                                                       pollutant removal                                    general avian habitat
                            50           Approximately 75% or greater sediment and                Minimal general wildlife habitat value
                                                       pollutant removal
                            75           Approximately 80% sediment and pollutant           Fair-to-good general wildlife and avian habitat value
                                                         removal
                            100          Approximately 80% sediment and pollutant            Good general wildlife habitat value; may protect
                                                         removal                                        significant wildlife habitat
                            200          Approximately 90% sediment and pollutant           Excellent general wildlife value; likely to support a
                                                         removal                         I                  diverse community
                            600          Approximately 99% sediment and pollutant           Excellent general wildlife value; supports a diverse
                                                         removal                               community; protection of significant species



               but does result in a given buffer width that will                            Despite its limitations, the modeling approach is
               better approximate a specific performance standard.                     often considered the most accurate and dependable
               The modeled approach, however, will only be as                          method of delineating vegetated buffer widths, and
               good as the site-specific data from which the model                     is commonly used by regulatory agencies. A strictly
               is run. High quality data for use in a model will                       modeled approach, because it is based solely upon
               often be expensive (e.g., time put into collecting it),                 "real" data, leaves less room for argument of re-
               which may limit its overall practicality for general                    quired buffer widths (other than whether or not the
               use in resource management programs. Further-                           input data or the actual model is appropriate) and is
               more, most modeled approaches only consider one                         therefore generally viewed as more "justifiable."
               vegetated buffer benefit - pollutant removal, for                       Since a strictly modeled approach is very "black-
               instance - and neglect other potential benefits.                        and-white," it is generally inflexible, and may limit
               Many of the existing buffer delineation models were                     full implementation of multiple-use vegetated
               developed to mitigate construction impacts, and                         buffers by resource managers. Using a modeled
               therefore may not be readily applicable in establish-                   approach to determine buffer widths to achieve a
               ing multiple-use vegetated buffers in already devel-                    given pollutant removal standard, and then review-
               oped or undeveloped areas. A further limitation to                      ing the modeled buffer width using best professional
               the site-specific modeled approach is that regulatory                   judgment to achieve other benefits (e.g., provision
               staff will be required to delineate vegetated buffers                   of wildlife habitat) may provide more flexibility and
               on a case-by-case basis, which could become time                        a better multiple-use vegetated buffer program.
               consuming. Furthermore, permit applicants will not                           Each approach to the application of vegetated
               be able to incorporate vegetated buffer widths                          buffers as a management tool has both good and bad
               during the initial design process. This will add cost                   points, and it will be up to the implementing author-
               to all development requiring a permit, and the cost                     ity to determine what trade-offs are the most reason-
               will be bome by both the permit applicant and the                       able and the most acceptable. Costs and benefits
               pen-nitting agency.                                                     will have to be weighed and examined in light of the


                                                                                                                                                          33









            uncertainty, restrictions, and flexibi lity inherent in       canopy. Wherever possible, wetlands          both
            each of the different approaches.                             coastal and inland -- would be incorporated into the
                                                                          buffer area. These areas most often provide the
                 The "Ideal" Buffer                                       conditions that are conducive to denitrification, as
                Although it is not possible to develop- a "one            well as often providing valuable habitat. Further-
            best" vegetated buffer for all purposes, it is possible       more, upland buffers would be designated around
            to describe the components of an "ideal" vegetated            wetland areas to provide habitat for the in   any
            buffer for multiple use. If the vegetated buffer is           animals that use wetlands as feeding and foraging
            intended to reduce pollutant inputs -to waters from           areas but rely upon the uplands for breeding sites
            nonpoint sources, provide wildlife habitat, and               and refuge from predators.
            establish a visual and physical barrier, it is possible           Vegetation species growing in the buffer would
            to develop a general description of an ideal veg-             be native, or species that are known to grow in
            etated buffer. This description may prove useful in           similar habitat and climate. Ornamental species may
            creating vegetated buffers that will perform within           be appropriate, provided they will not exclude or
            expectations and provide the results for which they           outcompete *native species. Many state agencies or
            were established.                                             nongovernmental organizations - land trusts,
                                                                          universities, and botanical societies - have put
                Contour                                                   together pamphlets that list and describe plant
                The ideal multiple-use vegetated buffer for the           species native to a region. These publications would
            removal of pollutants, regardless of width, would be          be consulted when planning a vegetated buffeT to
            relatively flat in contour in order to promote shallow        best e'nsure an indigenous cover within the buffer
            sheet flow through the buffer. This would increase            area.This is important for ensuring the longevity of
            residence time, allow greater absorption of water             the vegetation in the buffer, for providing adequate
            into the soil layer, and reduce the probability of            cover and forage for resident species, and for
            channelized flow. The v(-,getated buffer would not            preventing problems associated with invasions of
            have any gullied or channelized areas within it.              nonnative species. -       'I I
            Similarly, the landscape surrounding and leading                  To provide greatest value to wildlife, the ideal
            into the buffer would not promote channelized flow            buffer would contain a mix of vegetation that fruits
            into the buffer area, and would have adequate                 on a progressional schedule in order to provide     a
            vegetation or engineered design to reduce sedimen-            variety of feed types over the greatest length of
            tation at the leading edge of the buffer zone. Engi-          time. Vegetation in the buffer would be as randomly
            neered designs might include the installation of              distributed as possible- woody vegetation inter-
            level spreaders, or mechanical grading of the soils to        spersed with areas of grass - to provide increased
            produce a less steep slope, and/or alteration of the          diversity within the buffer habitat landscape. W-g-
            "preferred" direction of surfaceflow to promote               etation of various heights and canopy thickness
            shallow sheet flow into the buffer.                           would provide the greatest diversity to avian wild-
                                                                          life, and would promote use by the greatest diversity
                Vegetation                                                of birds, as well as other fauna. Some bird species
                Ideally, the vegetation within.the multiple-use              herons and osprey, for example - require. large
            vegetated buffer would consist of a mix of species.           trees as nesting sites, and providing some large trees
            The leading edge of the buffer might consist of a             in the- vegetated buffer would promote the nesting
            thickly growing grass maintained at a height of               activities of these and other species.
            about four inches. Beyond the grassy area would                   For aesthetic appeal, a mix of vegetation would
            grow a mix of trees, brush, and possibly native               provide visual diversity. Although some tall trees
            grasses. The species of trees would have well-                within the buffer area would be kept to provide
            developed root systems capable of exploiting                  canopy habitat, short trees and brush would be
            nitrogen stores traveling in groundwater, particu-            dispersed throughout the buffer to allow water
            larly in areas that are serviced by septic systems.           views from areas landward of the leading edge of
            Brush or woody-stemmed understory species would               the buffer. Based upon vegetation type and pollutant
            also provide a well-developed root system. and                uptake rates, the buffer area would be determined to

            34









           remove a given portion of those pollutants of                   Although the ideal vegetated buffer may not be
           concern, and then aesthetically fit into the landscape      realized under most circumstances, the concept of
           based upon development patterns and paths of                the ideal buffer is useful as a reference or goal
           surface water flow.                                         during design and implementation phases. It can
               The ideal multiple-use vegetated buffer would           help ensure that the buffers that are eventually
           be designated in existing natural areas. Designating        implemented will contain the most desirable traits
           vegetated buffers composed of existing vegetation           possible, given natural limitations and site restric-
           assures the habitat value of the buffer to the support      tions, and thereby be the most practical. The closer
           of native species. Designation of preexisting veg-          to the ideal a given buffers becomes, the more
           etated areas as buffers is also more economical since       closely it will serve its intended purpose and pro-
           the costs of design and engineering are avoided.            vide the anticipated results.










































                                                                                                                              35


















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                         W"9=






















                                         *'Ar

                                                                                                                71-





                                                                                                                -le








                                                                                17.







            111. Use of Vegetated Buffers in                             area of vegetated buffer. If estimates of pollutant
                                                                         input to the vegetated buffer can be arrived at -
            the Coastal Zone                                             through nonpoint source loading models, for in-
                                                                         stance - an estimate of removal efficiency can be
                 N Application and Approach                              obtained for a given buffer area. Given the rapidity
                 Vegetated buffers hold the promise of being an          of the growth and sophistication of nonpoint source
            effective multiple-use management tool for sustain-          loading models and computerized geographic
            ing the diverse uses of the coastal zone. The range          information systems, it is not unrealistic to imagine
            of multiple-use vegetated buffer widths, five to 200         calculating pollutant loadings to the coastal zone,
            meters (or more; see Table 7), provides resource             locating sensitive habitat areas or especially scenic
            managers with a set of tools that can be applied             or otherwise "special" areas, deten-nining the
            according to developmental conditions along the              vegetated buffer area required to provide expected
            coast. It also allows flexibility with regard to pur-        benefits, and then designing the location, extent, and
            pose and use of the multiple-use vegetated buffer            configuration of the vegetated buffer.
            area. Adopting some form of vegetated buffer                     Some coastal areas, such as historical seaports
            program that applies minimum buffer widths ac-               and coastal villages, gain much of their charm and
            cording to existing or potential development and             ambiance by their location directly on the water. In
            density, as well as applying wider buffer zones              such instances, a vegetated buffer may be inappro-
            around areas of critical concern, can result in the          priate, and other ways to mitigate nonpoint source
            development of a contiguous, or nearly contiguous,           pollution impacts and create wildlife habitat, if
            band of vegetated land bordering the coast. Such a           possible, may need to be considered. Resource
            program will assist in reducing the nonpoint source          managers will have to evaluate the various uses of
            contribution of pollutants flowing into coastal              their coastal zone, decide on a vegetated buffer
            waters, provide a diversity of wildlife habitats,            approach, and then define where and how to imple-
            provide for the protection and enhancement of                ment the vegetated buffer program.
            scenic and aesthetic appeal of the coastal zone,
            promote flood and erosion control, and provide a                 0 Public Perception
            visual and physical transition zone between public               It is important to acknowledge that humans are a
            and private coastal properties. Development of such          species that utilizes the coastal zone for a variety of
            a program is realistic, equitable, and feasible.             purposes. This must be not only considered, but
                 A coastal zone buffer policy can be readily             incorporated into vegetated buffer policy. Design
4           established using a variety of available resources.          and implementation of a coastal vegetated buffer
11
 4          U.S  :Geological Survey topographic maps, town               zone program that disregards human use of the
 J          zoning maps, aerial photographic survey results, or          coastal zone is bound to meet both resentment and
            Geographical Information Systems (GIS) databases             resistance, which could potentially be great enough
            can readily be used to interpret conditions along the        to force the abandonment of the use of this impor-
 A          coast, and then to establish vegetated buffer widths         tant management tool for preserving and protecting
 4          for a given region. Habitat for rare, threatened, or         coastal resources.
            endangered species; areas particularly prone to                  Establishing a program that utilizes vegetated
            erosion and/or flooding; areas bordering poorly              buffers for multiple use - pollution control, wild-
            flushed estuaries or significant shellfish beds; and         life habitat, scenic improvement - would help in
            areas of particular historic or scenic significance          making the program more appealing to a wider aud-
            may be identified as critical resource areas by              ience. Furthermore, a multiple-use approach to a
            coastal managers, and larger buffer widths imple-            coastal vegetated buffer program would make the
            mented to provide for a greater degree of protection         results of its implementation more "real" in the eyes
            and/or preservation,                                         of many. Increased scenic improvement, or greater
                 Although the removal rates presented in Table 2         wildlife sightings, are both very tangible, very visi-
            cannot be used directly to provide a required width          ble, and very real public "benefits" of a multiple-use
            for implementing a vegetated buffer, they can be             buffer program. Certainly they are more tangible
            used to estimate annual removal rates for a given            than increased pollutant removal, which is often in-

                                                                                                                                 37










             visible to, and misunderstood by, the general public.             access to the water's edge, and the trails would be
                 The ideal buffer -program, however, would be                  checked and maintained on a regular basis for
             one that is acceptable to the landowner who is being              erosion -or promotion of channelized flow through
             requested to-"donate" the fringe of coastal acreage               the buffer area. An occasional picnic table, gazebo,
             for the benefit of the public. Certainly the private              or similar use structure might be suitable within
             landowner will gamer some benefit from the pro-                   some vegetated buffers, provided it promotes
             gram - increased wildlife sightings and the pres-                 neither a loss of effectiveness nor overuse of the
             ence of a natural barrier between his personal lands              buffer as a travel zone to and from the structure.
             and those of the public, for instance - but resent-               Areas that have buffers established to protect critical
             ment due to land use limitations is often -felt by                habitat or significant wildlife may not be suitable
             private landowners. Given some leeway,for manipu-                 for any manipulation for recreational use. Such
             lation and use of the buffer area, most landowners                manipulation will have to be assessed on a case-by-
             will feel less threatened by the program's        infringing      case basis in order to ensure that the original intent
             upon their rights of ownership and use..                          for which the buffer was established is not jeopar-
                                                                               dized. Appendix B provides an example of a mul-
                 0 Management and Maintenance                                  tiple-use vegetated buffer management and mainte-
                 Regulatory agencies should develop a vegetated                nance program. This example is taken from the
             buffer use, maintenance, and management booklet                   Rhode Island Coastal Resources Management
             that outlines to abutting landowners what is permis-"             Program (CRMP), and was developed to comple_
             sible within the buffer, information sources for the              ment the vegetated buffer policies for the state of
             proper maintenance and management of the buffer                   Rhode Island CRMP (Appendix A@.
             area, and a calendar and schedule of recommended                      All woody-stemmed species of vegetation
             or required maintenance procedures. An assessment                 would be pruned and trimmed on a schedule to pro-
             of implemented buffers by Castelle et al. (1992)                  mote vigorous growth and utilization of nutrients.
             reported that 95 percent of the assessed buffers                  As trees and brush mature, or as individual plants
             showed signs of alteration after their implementa-                succumb to natural causes, selective harvesting
             tion. In all cases where the buffer was part of a                 would maintain a vigorously growing and diverse
             resident'ial lot, the buffer was eventually replaced              plant community. Leaf litter and other organic debris,
             with lawn by the homeowner. The authors suggest                   providing that it does not present a hazard or limit
             that a lack of clear'use and management objectives                other intended uses of the buffer area, would not be
             for the buffer, as well  "as a lack of buffer monitoring,         removed from the buffer area. The breakdown of
             resulted in the high alteration rate. A strong public             leaf litter provides a natural source of carbon to the
             education program implemented with the adoption                   soil layer, which is one requirement for the process
             of the buffer policy into the regulatory framework                of denitrification. Considering that coastal waters
             will go a long way toward helping landowners                      Are generally nitrogen-sensitive, and nitrate is a
             understand why the buffers were established and                   readily usable form of nitrogen in marine waters, the
             how.landowners can use and maintain these areas.                  promotion of denitrification in coastal zone veg-
             This is supported by the findings of Castelle et al.              etated buffers should be considered a priority. G
                                                                                                                                          Irass
             (1992), who note that buffers on the property of                  clippings may or may not be removed from the buf- -
             landowners who understood the purpose of the                      fer area, and worn or thin spots may be overseeded.
             buffers were less affected by homeowner manipula-                 -Although neither fertilizatio 'n nor watering of the
             tion and impact than those buffers on property of                 buffer area would be needed as a regular maintenance
             landowners who had little or no understanding of                  activity, either or both might be appropriate in estab-
             buffer purpose.                                                   lishing new buffer areas or restoring existing ones.
                The management of coastal zone multiple-use
             vegetated buffers will need to balance landowners'                   'N An Example: Rhode Island's Coastal
             rights to use of their property with maintenance of                      Buffer Program
             the purpose for which the buffer was originally                       An example of multiple-use vegetated buffer
             implemented. Winding trails and footpaths would be                policies that have been developed for use in the
             allowed within the vegetated buffer to provide                    coastal zone of Rhode Island. is provided in Appen-

             38










             dix A. It applies various-sized, fixed-width veg-              are applied on small lots so as not to cause the lots
             etated buffers, based on the summary given in Table            to become unusable, and with the realization that
             7, for residential lands; a fixed-width buffer on areas        pollutant removal will be limited and habitat value
             of concern or significance; and a case-by-case                 minor. As lot size increases, wider buffers are
             approach to other development, such as industrial,             implemented, increasing their value for pollutant
             residential subdivisions, and commercial uses.                 removal, wildlife habitat, and visual appeal.
                  The Rhode Island example institutes vegetated              I In all cases, and for all lot sizes, wider buffers
             buffers along the entire coastline of the state, while         are implemented where they border waters whose
             taking into consideration land parcel size and                 primary use has been designated Type I - Conser-
             existing coastal development patterns. The program             vation, or Type Il - Low Intensity Boating. The
             strives to strike a balance between land use by the            reasoning is that these types of waters require a
             homeowner and protection of coastal resources. The             higher degree of protection and preservation in or-
             widths of the established buffers are determined               der to maintain their designated primary uses. Wider
             according to lot size and Coastal Resources Man-               buffer widths are also applied when the area receiv-
             agement Council (CRMC) water type. The CRMC                    ing the buffer abuts an area of critical concern, special
             water type is a designation of the predominant use             significance, or scenic or historical importance.
             of coastal waters (i.e., I-Conservation Areas; 11-Low               The actual regulatory program, as adopted by
             Intensity Boating; III-High Intensity Use; IV-                 the state of Rhode Island, is included in Appendix A
             Multipurpose Waters; V-Commercial and Recre-                   exactly as it appears in the state's regulatory coastal
             ational Harbors; VI-Industrial Waterfronts and                 program documentation. Appendix B includes a
             Commercial Navigation Channels). Special mea-                  complementary vegetated buffer maintenance and
             sures (e.g., wider buffers) are applied along areas            management document created as part of the veg-
             that are considered critical or sensitive, such as             etated buffer program implemented by the Rhode
             wetlands or habitat that is used by rare, threatened,          Island CRMC.
             or endangered species.
                  The vegetated buffer policies and regulations                  E State Coastal Buffer Programs:
             are limited to residential areas (existing and infill)                 A Summary
             and allow for limited use of the buffer areas so that               This review of coastal states' programs, poli-
             homeowners are not unduly denied use oftheir                   cies, and/or regulations that could be used to estab-
             coastal property. These policies and regulations are           lish vegetated buffers along the coastal zone con-
             used as guidelines for other types of development              cerns itself only with those that are a part of the
             (commercial/industrial), but the final determination           states' Coastal Zone Management Programs. Poli-
             of buffer width for development other than single              cies and regulations applied by other state agencies
             family residential is performed on a case-by-case              are mentioned when the state CZMP defaults to
             basis by CRMC staff engineers and biologists to                other programs to avoid replication, or when no
             mitigate any potential impacts to the coastal zone.            CZMP has been established for a given state.
                  The Rhode Island vegetated buffer program was             Finally, despite the fact that the shores of the Great
             developed to provide for multiple uses and multiple            Lakes are considered under the federal coastal zone
             benefits. During development of the program, it was            management program, this review restricts itself to a
             quickly realized that implementing vegetated                   description of those states bordering saltwater
             buffers that would provide both high pollutant                 coastlines'*
             removal and high quality habitat was not practical in               Table 8 provides an overview and summary of
             all coastal areas. Attempting to implement such                the differences among states' policies, regulations,
             buffers would either lead to the proposed program's            and requirements for the establishment of vegetated
             not being adopted, or to requests for variances on             buffers along the coastal zone. A similar description
             nearly all permit applications.                                of state buffer policies has been put together in
                  Given this, a program was developed that                  Castelle et al. (1992), but pertains strictly to wet-
             balances the landowners' rights and the CRMC's                 lands and buffers around wetlands. Readers with a
             mandate to "preserve, protect, and where possible,             particular interest in wetlands may want to review
             restore ecological systems." Narrow buffer widths              that document. The program descriptions given here

                                                                                                                                       39






            are based on a* review of published state programs             leaving vegetation along coastal areas being logged,
            and/or discussions with state agency personnel. Any            but the actual vegetated width preserved is deter-
            errors, omissions, or misinterpretations are those of          mined on a case-by-case basis. On city- and state-
            the authors.                                                   owned lands, a 100-foot no-cut zone is required,
                Of the twenty-three state programs reviewed,               while on private property there is a 66-foot no-cut
            four had buffer programs applying to the entire                zone. This relates to timber harvest areas only, and
            coastal zone as an element of their state coastal zone         as noted above, is subject to modification on a case-
            management programs. Two other states had buffer               by-case basis. No statewide coastal zone program
            elements that pertained only to a certain portion of           buffer requirement currently- exists.
            their coastal zone. Nearly all states had some fon-n
            of mitigation procedure that could be applied during               Californ  *ia
            the permitting process to establish vegetated buffers              The state of California buffer program focuses
            in the coastal zone. Construction or septic system             on wetland habitat protection. The program requires
            setbacks, which could be used to establish vegetated           a minimum 100-foot buffer around coastal wetlands,
            buffers, were reported by most states, although                with additional width required if adjacent lands. are
            many reported those to be established by town                  biologically significant, if sensitive wildlife inhabit
            rather than state regulations  '                               the buffer, if the area is highly susceptible to ero-
                The various setbacks and buffer policies being             sion, or if proposed development poses significant
            used by state coastal zone management programs                 potential impact. The 100-foot buffer@ however, is
            that could establish vegetated buffers range from 20           used -as guidance only, and may be negotiated on a
            feet to 300 feet of buffer width (excluding the                case-by-case basis. Buffer regulations may exist at
            possibility of no buffer). This represents a range of          local levels of government, and may be more or less
            buffer effectiveness (from Table 7) from fifty                 stringent than the 100-foot buffer guideline sug-
            percent pollutant removal and poor habitat 'Value to           gested by the state coastal program. Vegetated
            eighty percent pollutant removal and good general              buffers may be applied to riparian areas when
            wildlife habitat value. No state program had policies          coastal program jurisdiction is extended into water-
            or regulations that provided greater than 80 percent           sheds that drain into sensitive coastal areas.
            pollutant removal, and none provided buffer widths
            that were in the category (from Table 7) considered                Connecticut
            excellent as wildlife habitat, although either or both             The state of Connecticut coastal zone program
            could potentially be achieved during case-by-case              has policies that promote preservation of vegetated
            buffer development.                                            coastal areas but has no statewide requirements.
                                                                           Implementation of vegetated buffers or construction
                Alabama                                                    setbacks along the coast may occur through zoning
                The state of Alabama has a 40-foot construction            regulations and requirements at local levels of gov-
            setback requirement, but it is only applicable to land         ernment. Construction setbacks that do exist in local
            along-the shoreline areas immediately on the Gulf              zoning ordinances may vary by town throughout the
            Coast; it does not include back bays and coves.                coastal zone of the state. New    vegetated buffer
            The application of the 40-foot setback is meant to             policies and regulations are being drafted by state
            protect beach dune systems and is measured                     regulatory agencies. While these new policies are
            from the dune crest. Vegetated buffers may be estab-           generally focused on riparian systems, their applica-
            lished through local zoning regulations of coastal             tion may be extended into the state's coastal zone.
            districts but are not a requirement of the state
            coastal zone program.                                              Delaware
                                                                               In the state of Delaware, establishment of
                Alaska                                                     vegetated buffers in the coastal zone is not a re-
                In the state of Alaska, separate requirements for          quirement of the coastal zone management program
            coastal vegetated buffer areas may be established              but may occur at the local level, according to local
            through local government mandates for each re-                 zoning regulations. State CZMP staff may require
            gional borough. Regulations exist that require                 the establishment of a vegetated buffer during the

            40










                  Table 8. A listing of buffer and setback widths that coastal states have established through their coastal zone manage-
                  ment programs. M denotes the. width is mandated, while R denotes that the width is recommended only. [I foot = 0.305 meters]



                             State              Buffer Width            Status         Setback Width            Status                 Comments
                            Alabama                                                   40% Applies to Gulf          M         Primarily for dune protection and
                                                                                          Coast only                                   preservation
                            Alaska                                                    10Y city/state lands;        M         Applies only to tim r harvest
                                                                                      66' private property                              operations
                           California       100' around wetlands            R                                                Mainly for habitat preservation
                          Connecticut                                                                                           Through local ordinances
                           Delaware                                                   50'from mean high            M         Also through local ordinances
                                                                                          water mark
                             Florida                                                                                            Through local ordinances
                            Georgia                                                                                               No CZMP at present
                             Hawaii                                                   40' from shoreward           M          Applies to all islands in the
                                                                                      vegetation line; 20' if                    Hawaiian islands group
                                                                                       hardship shown
                           Louisiana                                                                                            Through local ordinances
                             Maine          75' along entire coast;         M                                                Also has a buffer management
                                             250' along sensitive                                                                        program
                                                wetland areas
                           Maryland         100' along Chesapeake           M                                             Case-by-case on non-Chesapeake Bay
                                                   Bay shore                                                                               shores
                        Massachusetts                                                                                           in process of development
                          Mississippi                                                                                              Rarely; case-by-case
                              New            100' along wetlands            M                                             The definition of wetlands includes
                           Hampshire                                                                                               the entire NH coast
                         New Jersey         0-300'on a case-by-case         R                                                Only along sensitive areas; local
                                                      basis                                                                      zoning supersedes state
                          New York                                                    75' from wetlands (30'       M         Vegetation not required in the
                                                                                      in New York City)                                   setback
                             North          30' around significant          M                                                Vegetation not required in buffer
                            Carolina                waters
                             Oregon                                                                                             Through local ordinances
                        Rhode Island        0-200' on a case-by-case        R         50' from the coastal         M            New buffer program being
                                                      basis                                 feature                                      reviewed
                        South Carolina                                                Variable, according to       R            Only applicable in coastal
                                                                                        erosional rates                      dunes; vegetation not required
                              Texas                                                                                              CZMP being developed
                            Virginia        100' along Chesapeake           M                                                Not required along other state
                                                   Bay shore                                                                           coastal areas
                          Washington                                                                                            Through local ordinances



                  permitting process on a case-by-case basis. Further-                                Florida
                  more, a 50-foot construction setback from the edge                                  In the state of Florida, vegetated buffers may be
                  of a water body or wetland is required, and may act                            established in the coastal zone as part of the permit-
                  as a vegetated buffer. The state coastal zone pro-                             ting process on a case-by-case basis, or as mitiga-
                  gram also requires the use of vegetation for shore-                            tion requirements due to proposed development
                  line stabilization as a first choice during the pen-nit-                       impacts. Furthermore, requirements for vegetated
                  ting process. Rip-rap or other engineered shoreline                            buffers may exist at local levels of government
                  stabilization structures may be allowed where                                  through implementation of construction setback
                  vegetation proves inefficient or impractical. A major                          regulations for development along the coast. State-
                  focus of the program is the creation of wetland areas                          mandated setbacks in the coastal zone relate only to
                  as the shoreline stabilization structure of choice.                            requirements for the setback of septic systems from
                                                                                                 coastal wetlands.


                                                                                                                                                                         41









              Georgia                                                  years. Pruning and other maintenance procedures
              The state of Georgia has, no statewide require-          are allowed, but complete removal of grasses or
          ments for the establishment of vegetated buffers,            understory in the buffer is prohibited. A vegetated
          and at present is not a participant in the federal           buffer 250 feet wide is required along areas border-
          coastal zone management program. A Marshland                 ing sensitive wetlands. The larger buffer width is
          Protection Act may create vegetated buffers in the           implemented to provide added protection to wild-
          coastal zone adjacent to protected marshes (or as the        life, especially waterfowl, while the minimum
          marsh itself), but the primary purpose of the Act is         buffer width of 75 feet is implemented for protec-
          to protect marshlands, not create vegetated buffers.         tion of water quality and visual appeal.
          The Shoreline Protection Act gives'state regulatory              The buffer applies to new construction only., and
          agency staff some discretionary power to establish           preexisting lots are exempt from the 75-foot buffer
          vegetated coastal buffers through the permitting and         requirement. Preexisting Jots may not expand by
          review process.                                              greater than 30 percent, may not expand toward the
                                                                       water's edge, and if outside the 75-foot buffer zone,
              Hawaii                                                   may not extend into the buffer area during expari-
              The state of Hawaii has policies and regulations         sion. Local zoning ordinances may require a greater
          within the state coastal zone program to establish           buffer width than the minimum 75-foot buffer
          vegetated buffers along the coast. For all of the            mandated by the state program.
          Hawaiian island group, a 40-foot shoreline setback
          is requiredi beginning at the shoreward edge of the              Maryland
          coastal vegetation line and extending inland. The                It is the policy of the Maryland coastal zone
          buffer is generally intended to remain in an undis-          program to promote the establishment of vegetated
          turbed state, but certain uses are allowed, and vari-        buffers along the coast, and buffers may be required
          ances may be sought for limited development within           on a case-by-case basis,, particularly around wetland
          the buffer. In cases in which hardship can be proven,        areas. As part of the Chesapeake gay Program, all
          the mandatory 40-foot setback buffer can be reduced,         land 1000 feet inland of the shoreline of the Chesa-
          to 20 feet. Each of the islands in the Hawaiian island       peake Bay and its tributaries is subject to a 100- foot
          group may develop its own regulations with. regard           buffer requirement. The buffer requirement may be
          to the shoreline setback, but the width may not be           waived if "good conservation practices" are em-
          less than the 40 feet mandated by state regulations.         ployed at the shoreline site. Furthermore, the buffer
                                                                       requirement is only applicable to new development
              Louisiana                                                - existing development and previously plattedlots
              The state of Louisiana has no statewide policies         are "grandfathered" to p, reexisting requirements.
          or regulations that establish vegetated buffers in the       Other state programs share the cost of buffer strip
          coastal zone. Vegetated buffer areas may be estab-           implementation with farmers actively using land.
          lished on a case-by-case basis as part of the -state         bordering the Chesapeake.Bay and its tributaries.
          permitting process. When established, buffers are                The major emphasis of this policy has been in
          used to protect significant habitat or resources by          tidal tributaries of Chesapeake Bay. The emphasis in
          moving. development activities away from the                 non-Chesapeake Bay portions of the Maryland
          resource to a region of minimal im -pact.                    coastal zone has been on stabilization of the coast
                                                                       by promoting planting and preservation of vegetated
              Maine                                                    areas. Vegetation within,the buffers along the coast
              The state of Maine, as part of its Shoreline             has focused on grass species, while woody-
          Zoning Act, has implemented a coastal vegetated              stem med species have received greater emphasis
          buffer establishment program. The coastal zone               along tidal tributaries.
          program mandates a 75-foot minimum vegetated                     Plummer (1993) provides a more comprehen-
          area, measured from mean high water, along the               sive review of Maryland buffer policies and regula-
          entire Maine coast. The buffer must be kept in a             tions, as well as a review of implementation within
          vegetated state, with no more than 40 percent of             the coastal zone program.
          existing trees in the buffer being harvested every      10

          42









                  Massachusetts                                          Jersey buffer policy and regulations, as well as
                  The state of Massachusetts coastal zone pro-           implementation examples.
              gram does not currently have policies or regulations
              that establish vegetated buffers along the coast.              New York
              Establishment of vegetated buffer areas may occur              The general policy of the state of New York
              at local levels of government through zoning ordi-         coastal zone program is to protect significant coastal
              nances and regulations, or may be established on a         resources and habitats, and therefore vegetated
              case-by-case basis through the coastal zone program        buffer areas may be established during the permit-
              permitting process. The state coastal zone program,        ting process on a case-by-case basis. The state
              however, is in the process of developing a buffer          coastal zone program encourages the protection and/
              zone program, which is presently being drafted.            or planting of vegetation along the shoreline, but
                                                                         does not require it as part of the program mandate.
                  Mississippi                                                Through the regulatory program of the Depart-
                  The state of Mississippi coastal zone program          ment of Conservation, a construction setback
              has no statewide policies or regulations that estab-       regulation exists that may establish vegetated buffer
              lish vegetated buffers in the coastal zone. During the     areas. The regulations require a setback from
              permitting process, however, vegetated buffers that        wetland areas of 75 feet (30 feet in New York City).
              consist solely of tidal wetlands may be established        The setback regulation does not require that the
              to protect significant resources and habitats. The         buffer area be vegetated, but encourages the use of
              establishment of vegetated buffer areas applies only       vegetation. Local government may develop and
              to tidal wetland environments, and does not apply to       implement vegetated buffer policy and regulations
              upland areas adjacent to the coast.                        according to local zoning ordinances.

                  New Hampshire                                              North Carolina
                  The state of New Hampshire coastal zone                    In the state of North Carolina, the portion of the
              program, through state wetlands regulations, re-           coastal zone that lies within 75 feet of the water's
              quires the establishment of a 100-foot vegetated           edge is subject to permit approval for development
              buffer around coastal wetlands, beginning at the           purposes. Vegetated buffers may be established
              mean high tide mark. Although the buffer area is a         through the permitting process on a case-by-case
              requirement, activities can still be conducted             basis. When buffer areas are established, they need
              within the buffer, provided that proper permits have       not be vegetated as a requirement, but vegetation is
              beenissued.                                                encouraged. A 30-foot buffer is required around
                                                                         waters that are classified as high quality and/or of
                  New Jersey                                             high significance, but the buffer need not be veg-
                  The state of New Jersey has a coastal zone             etated. The 30-foot buffer requirement is most
              program element that may be used to establish              typically used to protect public water supply water-
              vegetated buffers along the coast. The program             shed areas. Local zoning ordinances may require the
              element requires a buffer width of 0 to 300 feet,          establishment of vegetated buffers along the coast.
              determined on a case-by-case basis, and is depen-          Phillips (1989d) reviews some local-level buffer
              dent on the potential impact to water resources from       requirements in North Carolina.
              the proposed development activity. The buffer
              program applies to private property, and to all                Oregon
              activities conducted in the coastal -zone by any state         The state of Oregon has several statewide
              agency. The buffer program, however, is only               policies that require local governing bodies to be
              applicable to those areas of the shoreline designated      consistent in their planning and zoning efforts.
              as significant or sensitive areas. Furthermore, local      Statewide policies to preserve and protect signifi-
              plans and zoning ordinances supersede the state            cant coastal habitats, cultural and historic resources,
              coastal buffer program, and do not have to be              and scenic qualities may result in the establishment
              consistent with state coastal zone policy. Plummer         of vegetated buffers along the coastal zone through
              (1993) provides a more detailed review of New              local adoption and implementation. Areas marked

                                                                                                                               43









          for preservation and/or restoration in estuaries may         program deal with the concept of vegetated (and
          also be viewed as vegetated buffers.                         nonvegetated) buffers.

              Rhode Island                                                 Virginia
              The state of Rhode Island coastal zone program               The state of Virginia has a buffer program
          has a policy for the establishment of vegetated              applicable to the shoreline of the Chesapeake Bay
          buffers, but it is implemented on a case-by-case             under the Chesapeake Bay Preservation Act, but the
          basis under the purview of program staff. When               program does not apply to other coastal areas in the
          applied, the buffer is measured from the inland edge         state. The coastal zone program recommends the use
          of the coastal feature (as defined by the program),          of vegetation and vegetated buffer areas for shore-
          with buffer width based on potential impacts of              line stabilization and other uses, but it is accom-
          development and the sensitivity and use of the               plished on a voluntary basis by property owners.
          adjacent land and water. The state coastal zone                  Along the shores of the Chesapeake Bay, the
          program also requires a minimum 50-foot construc-            Chesapeake Bay Preservation Act requires a 100-
          tion setback, but local zoning ordinances or regional        foot vegetated buffer along all shoreline that drains
          Special Area Management Plans may require the                to or is adjacent to the Chesapeake Bay. The pro-
          establishment of a buffer area, or require a greater         gram does provide for limited use within the veg-
          setback distance.                                            etated buffer, and variances may be sought to utilize
              The state of Rhode Island has developed a more           lands within the buffer area. No variances will be
          complete vegetated buffer program, a final version           provided that result in less than a 50-foot vegetated
          of which is included in Appendix A. Adoption of the          buffer remaining along the shoreline (except for
          program occurred during early 1994. Appendix B               agricultural uses).
          contains a copy of the vegetated buffer management               Water-dependent uses - such as marinas and
          and maintenance document that accompanies the                docks - are generally allowable within the 100-
          state's buffer program.                                      foot buffer area. Agricultural land uses that abut the
                                                                       shoreline may seek a smaller vegetated buffer width
              South Carolina                                           of 50 feet, and a 20-foot buffer may be allowed for
              In the state of South Carolina, -vegetated buffers       agricultural purposes, provided that a management
          may be established on a case-by-case basis along or          plan has been developed and is actively being
          within critical or sensitive areas, such as salt             implemented. Plummer (1993) provides a more
          marshes. Typically, the program regulates activity           complete review of the Virginia Chesapeake Bay
          within the critical or sensitive areas, rather than          Preservation Area Program, as well as implementa-
          establishing buffers around them. The coastal zone           tion examples.
          program also has jurisdiction within a setback area
          inland of coastal dune systems. The setback width is             Washington
          determined by erosional rates, and although veg-                 The state of Washington coastal zone prograrn
          etated buffers could be established within the               recommends the use of vegetated areas for shoreline
          coastal setback, the focus of the program is to              stabilization and other purposes, but does not
          regulate activity in the setback area rather than to         require their use. Each of the coastal counties in the
          establish it as a buffer area. The overall intent of the     state is required to develop its own master plans and
          setback.is to protect property by removing structures        zoning ordinances, which may, but are not required
          from erosional zones along the coast.                        to, include regulations for the establishment of
              Texas ,                                                  vegetated buffers at a local level.
              The state of Texas is in the process of develop-
          ing its coastal zone program, and therefore at
          present has no policies or regulations that establish
          vegetated buffers along the coast. The program that
          is in development recognizes the value of coastal
          buffer zones, and several policies within the draft

          44
















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               IV. Selected Bibliograph                                                      Adams, L.W. and L.E. Dove. 1984. Urban wetlands for
                                                                   Y                    stormwater control and wildlife enhancement. National
                                                                                        Institute for Urban Wildlife. Columbia, MD. 15 pp.
                    This bibliography represents a search of the                             Adams, L.W. and D.L. Leed (eds.). 1987. Integrating man
               literature for works that relate to vegetated buffers.                   and nature in the metropolitan environment. National Institute
               The selected bibliography presents a wide range of                       for Urban Wildlife. Columbia, MD. 249 pp.
               subjects, ranging from pollutant removal research to
               the aesthetic and scenic value of vegetated buffers.                          Adams, L.W., T.M. Franklin, L.E. Dove, and J.M.
               The selected works are definitely biased towards                         Duffield. 1986. Design considerations for wildlife in urban
               research on pollutant removal efficiency of veg-                         stormwater management. Transactions of the North American
               etated buffers. The reason for this is twofold: (1) the                  Wildlife and Natural Resources Conference 51:249-259.
               bulk of the published literature is the results of                            Ahola, H. 1990. Vegetated buffer zone examinations on
               research with this as their focus, and (2) in light of                   the Vantaa River basin. Aqua Fennica 20(l):65-69.
               the recent emphasis on control of nonpoint source                             Allen, H.H. 1979. Role of wetland plants in erosion
               pollutants, this portion of the literature is extremely                  control of riparian shorelines. In: P.E. Greeson, J.R. Clark, and
               valuable in pursuing the use of vegetated buffers as                     J.E. Clark (eds.), Wetland Functions and Values: The State Of
               a nonpoint source control mechanism. However,                            Our Understanding. American Water Resources Association
               the selected references presented here represent a                       Technical Publication No. TPS79-2. pp. 403-414.
               reasonable introduction to the diversity of uses of                           Ambus, P. and R. Lowrance. 1991. Comparison of
               vegetated buffers as a multiple-use resource man-                        denitrification in two riparian soils. Soil Scientist Society of
               agement tool.                                                            America Journal 55:994-997.
                    Several bibliographies, some annotated, are                              Anacostia Restoration Team. 1992. A current assessment
               given in the following list of literature references.                    of urban best management practices: Techniques of reducing
               One of special note, however, is that compiled by                        nonpoint source pollution in the coastal zone. Metropolitan
               Dr. David Correll at the Smithsonian Environmental                       Washington Council of Governments. Washington, DC.
               Research Center (Correll, 1993). This bibliography                            Anderson, B.W. and R.D. Ohmart. 1985. Riparian
               is specific to the literature regarding forested buff-                   revegetation as a mitigating process in stream and river
               ers, and is indexed according to the parameters                          restoration. In: J.Gore (ed.), The Restoration of Rivers and
               researched in each citation given. The bibliography                      Streams. Butterworth Publishers. Boston, MA. pp. 41-80.
               also contains references culled from international                            Anderson, M.P. 1984. Movements of contaminants in
               sources, and provides       'a robust compendium of                      groundwater: Groundwater transport, advection, and disper-
               research in forested buffers.                                            sion. In: National Academy of Sciences, Groundwater
                                                                                        Contamination. pp. 37-45.

                    Abell, D.L. (ed.). 1989. Proceedings of the California                   Asmussen, L.E., A.W. White, Jr., E.W. Hansen, and J.M.
               Riparian Systems Conference: Protection, Management, and                 Sheridan. 1977. Reduction of 2,4-D load in surface runoff
               Restorationfor the 1990s. Pacific Southwest Forest & Range               down a grassed waterway. Journal of Environmental Quality
               Experiment Station Technical Report No. PSW- I 10. Berkeley,             6:159-162,
               CA. 115 pp.                                                                   Aubertin, G.M. and J.H. Patric. 1974. Water quality after
                    Aber, J.D., K.J. Nadelhoffer, P. Stendler, and J.M.                 clearcutting a small watershed in West Virginia. Journal of
               Melillo. 1989. Nitrogen saturation in northern forest ecosys-            Environmental Quality 3:243-249.
               tems. BioScience 39:378-386.                                                  Ault, G.H., T.L. Loudon, and I.B. Gerrish. 1979. Crop-
                    Adam, R., R. Lagace, and M. Vallieres. 1986. Evaluation             land, buffer, and stream: A field study. American Society of
               of beef feedlot runoff treatment by a vegetative filter. Ameri-          Agricultural Engineers Paper No. 79-2010. St. Joseph, MI.
               can Society of Agricultural Engineering Paper No. 86-208. St.                 Baker, D.E. and L. Chesnin. 1975. Chemical monitoring
               Joseph, MI.                                                              of soils for environmental quality and animal and human
                    Adams, L.W. and L.E. Dove. 1989. Wildlife reserves and              health. Advances in Agronomy 27:305-367.
               corridors in the urban environment: A guide to ecological                     Barfield, B.J., E.W. Tollner, and J.C. Hayes. 1979.
               landscape planning and resource conservation. National
               Institute for Urban Wildlife. Columbia, MD. 91 pp.                       Filtration of sediment by simulated vegetation. 1. Steady state
                                                                                        flow with homogeneous sediment. Transactions of the Ameri-
                                                                                        can Society ofAgricultural Engineers 22(3):540-545; 548.

                                                                                                                                                           47










                 Barker, J.C. and B.A. Young. 1984. Evaluation of a                    Broderson, J.M. 1973. Sizing buffer strips to maintain
            vegetative filter for dairy wastewater in southern Appalachia.        water quality. Master's of Science thesis, University of
            Water Resource Research Institute, North Carolina State               Washington. Seattle, WA. 84 pp.
            University. Raleigh, NC.
                                                                                       Brown, K.W., K.C. Donnelly, J.C. Thomas, and J.F.
                 Barnes, K.B. 1988. Cartographic modeling of nonpoint             Slowey. 1984. The movement of nitrogen species through
            pollutant surfaces for a coastal drainage area. In: Lyke and          three soils below septic fields. Journal of Environmental
            Hoban (eds.), Proceedings of the Symposium on Coastal Water           Quality 13:460-465.
            Resources. Technical Publication Series of the American Water
            Resources Association, MD. pp. 133-145.                                    Brown, K.W. and J.C. Thomas. 1978. Uptake of N by
                                                                                  grass from septic fields in three soils. Agronomy Journal
                 Bartlett, M.S., L.C. Brown, N.B. Hanes, and N.H.                 70:1037-1040.
            Nickerson. 1979. Denitrification in freshwater wetland. soil.
            Journal of Environmental Quality 8:460-464.                                Brown, M.T. and J.M. Schaefer. 1987. Final Report: An
                                                                                  evaluation of the applicability of upland buffers for the
                 Barton, D.R., W.D. Taylor, and R.M. Biette. 1985.                wetlands of the Wekiva Basin. Center for Wetlands, University
            Dimensions of riparian buffer strips required to maintain trout       of Florida. Gainesville, FL. 163 pp.
            habitat in southern Ontario streams. North American Journal
            of Fisheries Management 5:364-378.                                         Brown, M.T., J.M. Schaefer, and K.H. Brandt. 1990.
                                                                                  Buffer zones for water, wetlands and wildlife in cast central
                 Beaulac, M.N. and K.H. Reckhow. 1982. An examination             Florida. Center for Wetlands Publication No. 89-07. Florida
            of landuse - nutrient export relationships. Water Research            Agricultural Experiment Station Journal Series No. T-00061.
            Bulletin 18:1013-1024.                                                71 pp.

                 Best, L.B. 1983. Bird use of fencerows: Implications of               Bubenzer, G.D., J.C. Converse, and J.W. Patoch. 1989.
            contemporary fencerow management practices. Wildlife                  Downward movement of water below grass filter strips --
            Society Bulletin 11:343-347.                                          case studies. Department of Agricultural Engineering,
                                                                                  University of Wisconsin. Madison, WI.
                 Bingham, S.C., P.W. Westerman, and M.R. Overcash.
            1980. Effect of grass buffer zone length in reducing the                   Budd, W.W., P.L. Cohen, P.R. Saunders, and F.R. Steiner.
            pollution from land application areas. Transactions of the            1987. Stream corridor management in the Pacific Northwest: 1.
            American Society of Agricultural Engineers 23(2):330-335;             Determination of stream-corridor widths. Environmental
            342.                                                                  Management 11:587-507.

                 Bingham, S.C., M.R. Overcash, and P.W. Westerman.                     Burgess, R.L. and D.M. Sharpe (eds.). 1981. Forest
            1978. Effectiveness of grass buffer zones in eliminating              Island Dynamics In Man-Dominated Landscapes. Springer-
            pollutants in runoff from waste application sites. American           Verlag. New York, NY.
            Society of Agricultural Engineers Paper No. 78-2571. St. -                 Cain, D. 1989. Evaluations of regional groundwater
            Joseph, MI.
                                                                                  quality in relation to land use. Groundwater 27(2):230-244.
                 Blake, J.G. and J.R. Karr. 1984. Species composition of
            bird communities and the conservation benefit of large versus              Canter, L.W. and R.C. Knox. 1985. Septic Tank Effects
            small forests. Biological Conservation 30:173-187.                    On Ground Water Quality. Lewis Publishers, Inc. Chelsea, MI.
                 . Booth, N.K. 1983. Basic Elements of Landscape Architec-             Carter, W.R. 1988. The importance of buffer strips to the
            tural Design. Elsevier Science Publis  .hing Co., Inc. New York,      normal functioning of stream and riparian ecosystems.
            NY. 315 pp.                                                           Maryland Department of Natural Resources, Tidewater
                                                                                  Administration, Coastal Resources Division. Annapolis, MD.
                 Bormann, F.H., G.E. Likens, D.W. Fisher, and R.S.
            Pierce. 1968. Nutrient loss accelerated by clear-cutting of a              Casman, E. 1989. Effects of agricultural best management
            forest ecosystem. Science 159:882-884.                                practices on water quality as related to adjustments of HSPF
                                                                                  parameters, a literature review: 111. Parameters and concepts
                 Bowmer, K.H. 1987. Nutrient removal from effluents by            for modeling vegetated filter strips. The Interstate Commission
            an artificial wetland: Influence of rhizosphere aeration and          on the Potomac River Basin.
            preferential flow studies using bromide dye tracers. Water
            Resources 21:591-599.                                                      Castelle, A.J., C. Conolly, M, Emers, E.D. Metz, S.
                                                                                  Meyer, and M. Witter (eds.). 1992. Wetland buffers: An
                 Brinson, M.M. 1988. Strategies for assessing the cumula-         annotated bibliography. Washington State Department of
            tive effects of wetland alteration on water quality. Journal of       Ecology. Olympia, WA. 71 pp.
            Environmental Management 12:655-662.



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                   Ca'stelle, A.J., C. Conolly, M. Emers, E.D. Metz, S.                   Conner, W.H. and J.W. Day, Jr. 1988. Response of coastal
               Meyer, M. Witter, S. Mauermann, T. Erickson, and S.S.                 wetland forests to human and natural changes in the environ-
               Cooke. 1992. Wetlands buffers: Use and effectiveness.                 ment with emphasis on hydrology. In: D.D. Hook and R. Lea
               Washington State Department of Ecology Pub. No. 92-10.                (eds.), The Forested Wetlands of the Southern United States.
               Olympia, WA. 171 pp.                                                  pp. 34-43.
                   Chesapeake Bay Local Assistance Act. 1990. Chesapeake                  Cook College Department of Environmental Resources.
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                   Chescheir, G.M., R.W. Skaggs, and J.W. Gilliam. 1992.             1-89. New Brunswick, NJ.
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               Society of Agricultural Engineers 35:175-182.                         1989b. Buffer strips to protect water supply reservoirs and
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                   Chescheir, G.M., JW. Gilliam, R.W. Skaggs, R.G.                   Jersey Agricultural Experiment Station Report No. H-17505-
               Broadhead, and R. Lea. 1987. The hydrology and pollutant              2-89. New Brunswick, NJ.
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               pumped agricultural drainage water, Water Resources                        Cooper, A.B., C.M. Smith, and A.B. Boucher. 1992.
               Research Institute Report No. 23 1, University of North               Predicting runoff of water, sediment, and nutrients from a New
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                   Chescheir, G.M., R.W. Skaggs, JW. Gilliam, and R.G.
               Broadhead. 1988. Wetland buffer areas for treatment of                     Cooper, A.B. 1990. Nitrate depletion in the riparian zone
               pumped agricultural drainage water. In: Lyke and Hoban                and stream channel of a small headwater catchment.
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                   Clark, J. 1977. Coastal Ecosystem Management. John                Robarge. 1987. Riparian areas as filters for agricultural
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                   Clausen, J.C. and D.W. Meals, Jr. 1989. Water quality             420. Cooper, J.R., JW. Gilliam, and J.C. Jacobs. 1986.
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                Appendix A                                                                  2. Vegetated buffer zones have been applied as best
                                                                                       management practices within the fields of forestry and
                The Rhode Island Coastal Zone                                          agriculture since the 1950s to protect in-stream habitats from
                                                                                       degradation by the input of sediment and nutrients (Desbonnet
                Buffer Program                                                         et al 1993). More recently, vegetated buffer zones have gained
                                                                                       popularity as a best management practice for the control and
                                                                                       abatement of nonpoint source pollutants (contaminated runoff)
                     Adopted April 1994, RI CRMP                                       and are routinely applied in both engineered and natural
                                                                                       settings (Desbonnet et al 1993; EPA 1993).
                     Section 140 Setbacks                                                   3. Coastal Buffer Zones provide multiple uses and
                     Amend Section 140. C to read as follows:                          multiple benefits to those areas where they are applied
                                                                                       (Desbonnet et al 1993). The multiple uses and benefits of
                     11C. Setbacks shall extend a minimum distance of either           Coastal Buffer Zones include:
                fifty (50) feet from the inland boundary of the coastal feature             (a) Protection of Water Quality: Buffer zones along the
                or twenty-five (25) feet inland of the edge of a Coastal Buffer        perimeter of coastal water bodies can be effective in trapping
                Zone, whichever is further landward. In areas designated by            sediments, pollutants (including oil, detergents, pesticides,
                the Council as Critical Erosion Areas-(Table 2), the minimum           herbicides, insecticides, wood preservatives and other     .
                distance of the setback shall be not less than 30 times the            domestic chemicals), and absorbing nutrients (particularly
                calculated average annual erosion rate for less than four              nitrogen) from surface water runoff and groundwater flow.
                dwelling units and not less than 60 times the calculated               The effectiveness of vegetated buffers as a best management
                average annual erosion rate for projects proposing more than 4          ractice for the control of nonpoint source runoff is dependent
                dwellings units.                                                       P
                                                                                       upon their ability to reduce the velocity of runoff flow to allow
                     "SECTION 150 COASTAL BUFFER ZONES                                 for the deposition of sediments, and the filtration and biologi-
                                                                                       cal removal of nutrients within the vegetated area. In general,
                     A. Definition                                                     the effectiveness of any vegetated buffer is related to its width,
                     1. A Coastal Buffer Zone is a land area adjacent to a             slope, soil type, and resident species of vegetation. Effective
                Shoreline (Coastal) Feature that is, or will be, vegetated with        buffers for nonpoint source pollution control, which remove at
                native shoreline species and which acts as a natural transition        least 50%, and up to 99%, of sediments and nutrients entering
                zone between the coast and adjacent upland development. A              them, range from 15 feet to 600 feet in width.
                Coastal Buffer Zone differs from a construction setback                     The removal of pollutants can be of particular importance
                (Section 140) in that the setback establishes a minimum                in areas abutting poorly flushed estuaries that are threatened
                distance between a shoreline feature and construction activi-          by an excess of nutrients or are contaminated by runoff water,
                ties, while a buffer zone establishes a natural area adjacent to a     such as the South Shore Salt Ponds and the Narrow River.
                shoreline feature that must be retained in, or restored to, a          Large, well flushed water bodies, such as Narragansett Bay,
                natural vegetative condition (Figure 2). The Coastal Buffer            are also susceptible to nonpoint source pollutant inputs, and
                Zone is generally contained within the established construc-           can be severely impacted by nonpoint source pollutants as has
                tion setback.                                                          been documented in studies completed for the Narragansett
                                                                                       Bay Project.
                     Figure 2 An example of the application of a Coastal                    (b) Protection of Coastal Habitat: Coastal Buffer Zones
                     Buffer Zone.                                                      provide habitat for native plants and animals. Vegetation
                                                                                       within a buffer zone provides cover from predation and
                                                       Boundary of                     climate, and habitat for nesting and feeding by resident and
                                                     Construe tion Area                migratory species. Some species which use coastal buffer
                                                                                       zones are now relatively uncommon, while others are consid-
                      Inland Edge of the        Buffer                                 ered rare, threatened or endangered. These plants and animals
                        Coastal Feature-       Boundary                                are essential to the preservation of Rhode Island's valuable
                                                                                       coastal ecosystem.
                                                                                            The effectiveness of vegetated buffers as wildlife habitat
                                                                                       is dependent upon buffer width and vegetation type. In
                  Coastal                            Lawn
                  Feature       50' Vegetated Buffer                                   general, the wider the buffer the greater its value as wildlife
                                        75'CRMC Setback                   Septic       habitat. Larger buffer widths are typically needed for species
                              d                                           Field        that are more sensitive to disturbances (e.g., noise). Further-
                                                    CRNIC 200'Jurisdiction             more, those buffers that possess vegetation native to the area
                                                                                       provide more valuable habitat for sustaining resident species.
                       Ita'
                       tur@e

                     B. Findings                                                       A diversity of plant species and types (e.g., grasses, shrubs
                     1. The estab;ishment of Coastal Buffer Zones is based             and trees) promotes biodiversity within the buffer area, and the
                upon the CRMC's legislative mandate to preserve, protect and,          region overall.
                where possible, restore ecological systems.


                                                                                                                                                          65











                        (c)   Protection of Scenic and Aesthetic Quality: One of                                  managed in accordance with the standards contained in this
                 the primary goals of the Council is to preserve, protect, and                                    section. In cases where native flora (vegetation) does not exist
                 where possible restore the scenic value of the coastal region in                                 within a buffer zone, the Council may require restoration
                 order to retain the visual diversity and unique visual character                                 efforts which include, but are not limited to, replanting the
                 of the Rhode Island coast as seen by hundreds of thousands of                                    Coastal Buffer Zone with native plant species.
                 residents and tourists each year from boats, bridges, and such
                 vantage points as roadways, public parks, and public beaches                                            4. Coastal Buffer Zones shall remain covered with native
                 (Section 330). Coastal Buffer Zones enhance and protect                                          flora and in an undisturbed state in order to promote the
                 Rhode Island's scenic and visual aesthetic resources along the                                   Council's goal of preserving? protecting, and restoring
                 coast. Coastal buffers also preserve the natural character of                                    ecological systems. However, the Counciltray permit minor
                 the shoreline, while mitigating the visual impacts of coastal                                    alterations to Coastal Buffer Zones that facilitate the continued
                 development. Visual diversity provides for both contrast and                                     enjoyment of Rhode Island's coasta( resources. All alterations
                 relief between the coastal and inland regions, leading to                                        to Coastal Buffer Zones or alterations to the natural vegetation
                 greater aesthetic value of the landscape.                                                        (i.e., areas not presently maintained in a landscaped condition)
                                                                                                                  within the Council's jurisdiction shall be conducted in
                        (d) Erosion Control: Coastal Buffer Zones provide a                                       accordance with the standards contained in this section as well
                 natural transition zone between the open coast, shoreline                                        as all other applicable policies and standards of the Council.
                 features and upland development. Natural vegetation within a                                     In order to -ensure compliance with these requirements, the
                 Coastal Buffer Zone helps to stabilize the soil, reduces the                                     Council may require applicants to submit a Buffer Zone
                 velocity of surface water runoff, reduces erosion of the soil by                                 Management Plan.
                 spreading runoff water over a wide area, and promotes
                 absorption and infiltration through the detrital (leaf) layer and
                 underlying soils. The extensive root zones often associated                                      Table 2a.
                 with buffer zone vegetation also help prevent excessive                                          Coastal Buffer Zone designations for residential
                 shoreline erosion during coastal storm events by stabilizing                                     development.
                 underlying soils.                                                                                                                              Water Use
                        (e) Flood Control: Coastal Buffer Zones aid in flood                                           Residential Lot              Type        Category                      Type,
                 control by reducing the velocity of runoff and by encouraging                                                Size              3,    4, 5 &                                            & 2
                 infiltration of precipitation and runoff into the ground rather                                            (sq. ft.)                 6         Required      Buffer
                 than allowing runoff to flow overland and flood low -lying                                                                                               (f t)
                 areas. In addition, Coastal Buffer Zones often occupy the                                                  .<10,000                  15               ....................             25
                 flood plain itself and thus add to coastal flood protection.                                          10,000 - 20,000                25               ....................             50
                                                                                                                       20,001 - 40,000                50               ....................             75
                                                                                                                       40,001 - 60,000                75               ......... ..........             100
                        (f) Protection of Historic and Archa                .eological Resources:                      60,001 - 80,000                100              ....................             125
                                                                                                                       80,001 - 200,000               125*             ....................             150
                 Coastal Buffer Zones protect areas of cultural and historic                                                >200,000                  150              ....................             200
                 importance such as archaeological sites by helping prevent
                 intrusion while protecting the sites' natural surroundings.

                                                                                                                         5. In order to enhance conservation, protect water quality,
                        C. Policies                                                                               and maintain the low intensity use characteristic of Type I and
                                                                                                                  2 waters, greater buffer widths shall be applied along the
                        1. The establishment of a Coastal Buffer Zone i's based                                   coastline abutting these water types.
                 upon the CRMC's legislative mandate to preserve, protect and,
                 where possible, restore ecological systems. The determination                                           6. In critical areas and when the property owner owns
                 of the inland boundary of the Coastal Buffer Zone must                                           adjoining lots, these lots shall be considered as one lot for the
                 balance this mandate with the property owner's rights to                                         purposes of applying the values contained in Table 2a and
                 develop and use the property.                                                                    ensuring that the appropriate'buffer zone is established.

                        2. The Council shall require Coastal Buffer Zones in
                 accordance with the requirements of this section for the                                                D. Standards
                 following: a) new residential development; b) commercial and
                 industrial development; c) activities subject to Section 300.8                                          1. All Coastal Buffer Zones shall be measured from the
                 and Section 300.13; and d) inland activities identified in                                       inland edge of the most inland Shoreline (Coastal) Feature.
                 Section 320. For existing residential structures, the Councir
                 shall require a Coastal Buffer Zone for category "A'; and "B"                                           2. Coastal Buffer Zone Requirements for New Residential
                 activities when the RIDEM requires the modification or                                           Development: The minimum Coastal Buffer Zone require-
                 expansion of an existing septic-system or when the footprint of                                  ments for new residential development bordering Rhode
                 the structure is expanded.                                                                       Island's shoreline are contained in Table 2a. The Coastal
                                                                                                                  Buffer Zone requirements are based upon the size of the lot
                        3. The vegetation within a buffer zone must be either                                     and the CRMC's designated Water Types (Type I - Type 6).
                 retained'in a natural, undisturbed condition, or properly                                        Where the buffer zone requirements noted above cannot be

                 66@











                 met, the applicant may request a variance in accordance with            variance to these requirements in accordance with the burdens
                 Section 120. 1 A variance to 50% of the required buffer width           of proof contained in Section 120.
                 may be granted administratively by the Executive Director if
                 the applicant has satisfied the burdens of proof for the granting            6. All property abutting Coastal Natural Areas (Section
                 of a variance. Where it is determined that the applicant has            210.4) shall have a minimum vegetated Coastal Buffer Zone
                 not satisfied the burdens of proof, or the requested varriance is       of 25 feet from the inland edge of the coastal feature. The
                 in excess of 50% of the required width, the application shall           Executive director shall have the authority to grant a variance
                 be reviewed by the full Council.                                        to these requirements in accordance with the burdens of proof
                                                                                         contained in Section 120.
                      3. Coastal Buffer Zone Requirements for Existing
                 Residential Structures that Expand the Footprintofthe                        7. All property located within the boundaries of a Special
                 Structure andfor Structures Required by the RIDEM to Modify             Area Management (SAM) Plan approved by the Council shall
                 or Expand an Existing Septic System: When an existing                   meet additional buffer zone requirements contained within
                 residential structure does not meet the Council's Coastal               these SAM plans. When a SAM plan's buffer zone require-
                 Buffer Zone requirements contained in Table 2a (e.g., the               ments apply, the buffer width values contained in this section
                 existing structure does not have a buffer zone or has a buffer          will be compared to those required by the SAM plan, and the
                 zone with a width less than the value contained in Table 2a),           larger of the buffer widths applied.
                 the following Coastal Buffer Zone requirements shall apply to
                 each modification of the residential structure until the                     8. The setback (Section 140) for all new residential,
                 property's Coastal Buffer Zone equals, but does not exceed,             commercial, and industrial structures shall exceed the Coastal
                 the value contained in Table 2a:                                        Buffer Zone requirement by a minimum of 25 feet for fire,
                                                                                         safety, and maintenance purposes. Where the 25 foot separa-
                      (a) Where alterations to a residential structure result in         tion distance between the inland edge of the buffer and
                 the expansion of the structure's footprint (square footage of           construction setback cannot be obtained, the applicant may
                 the ground floor area encompassed by the structural founda-             request a variance in accordance with Section 120. The
                 tion of an existing building), the Coastal Buffer Zone require-         Executive Director shall have the authority to grant variances
                 ment shall be established with a width equal to the percentage          to this requirement. However, a vegetated Coastal Buffer
                 increase in a structure's footprint as of April 15, 1994 multi-         Zone shall not directly contact any dwelling's footprint.
                 plied by the value contained in Table 2a ([square foot increase
                 of footprint/square footage as of April 15, 1994] X value
                 contained in Table 2a = Coastal Zone Buffer Requirement);                    E. Buffer Management and Maintenance Requirements

                      (b) Where alterations to a residential structure result in an           1. All alterations within established Coastal Buffer Zones
                 increase in flow to the Individual Sewage Disposal System               or alterations to natural vegetation (i.e., areas not presently
                 (ISDS) and the RIDEM has required the modification or                   maintained in a landscaped condition) within the Council's
                 expansion of the existing ISDS, the Coastal Buffer Zone                 jurisdiction may be required to submit a Buffer Zone Manage-
                 requirement shall be established with a width equal to 25% of           ment Plan for the Council's approval that is consistent with the
                 the value contained in Table 2a (0.25 X value contained in              requirements of this section and the Council's most recent
                 Table 2a = Coastal Buffer Zone requirement).                            edition of Buffer Zone Management Guidance. Buffer Zone
                                                                                         Management Plans shall include a description of all proposed
                      These requirements only apply to category "A" and "B"              alterations and methods of avoiding problem areas such as the
                 assents. In addition, the Executive director shall have the             proper placement and maintenance of pathways. Applicants
                 authority to grant a variance to these requirements for category        should consult the Council's most recent edition of Buffer
                  A" assents in accordance with the burdens of proof contained           Zone Management Guidance when preparing a buffer manage-
                 in Section 120.                                                         ment plan.

                      4. Coastal Buffer Zone Requirements for all Commercial                  2. In order to promote the Council's goal to preserve,
                 and Industrial development and activities subject to the                protect and, where possible, restore ecological systems,
                 requirements of Section 300.8, Section 300.13, or Section 320:          Coastal Buffer Zones shall be vegetated with native flora and
                 Coastal Buffer Zones shall be determined on a case-by-case              retained in a natural, undisturbed condition, or shall be
                 basis by the Council. Table 2a may be used as appropriate               properly managed in accordance with Council's most recent
                 pidance. However, depending on the activity proposed and                edition of Buffer Zone Management Guidance. Such manage-
                 its potential impacts on coastal resources, the Council may             ment activities compatible with this goal include, but are not
                 require a Coastal Buffer Zone with a width greater than that            limited to:
                 found in the Table 2a.
                                                                                              (a) Shoreline Access Paths: Pathways which provide
                      5. All property abutting critical habitat areas, as defined        access to the shoreline are normally considered permissible
                 by the Rhode Island National Heritage Program or the                    provided they are less than or equal to 6 feet wide and follow a
                 Council, shall possess a minimum vegetated buffer zone of               path that minimizes erosion and gullying within the buffer
                 200 feet between the identified habitat and any development             zone (e.g., a winding, but direct path). Pathways should
                 area. The Executive director shall have the authority to grant a        avoid, or may be prohibited in, sensitive habitat areas,


                                                                                                                                                            67










             including, but not limited to, coastal wetlands. Pathways may                   (d) Safety and Welfare: Selective tree removal, pruning
             be vegetated with grasses and mowed or may be surfaced with                and. thinning of natural vegetation within a Coastal Buffer
             crushed  stone or mulch,                                                   Zone may be allowed by the Council on a case-by-case basis
                                                                                        for proven safety and welfare concerns (e.g., removal of a
                  (b) View Corridors: Selective tree removal and pruning                damaged tree in close proximity to a dwelling). In order to
             and thinning of natural vegetation may be allowed within a                 promote child safety and manage pets in areas harboring ticks,
             defined corridor in order,to promote a view of the shoreline.              fences along the inland edge of a Coastal Buffer Zone and
             Only the minimal alteration of vegetation necessary to obtain a            along shoreline access pathways may be permitted.
             view shall be acceptable to the Council. Shoreline access
             paths shall be located within view corridors to the maximum                     (e) Shoreline Recreation: The CRMC recognizes that
             extent practicable in order to minimize disturbance of Coastal             shoreline recreation is one of the predominant attractions for
             Buffer Z ones. View corridors shall be prohibited in sensitive             living on, or visiting the Rhode Island Coast. In order to allow
             or critical habitat areas.                                                 for such uses, minor alterations of buffer zones may be
                                                                                        permitted along the shoreline if they are determined to
                  (c) Habitat Management: Management of natural                         consistent with Council's requirements. These alterations may
             vegetation within a buffer zone to enhance wildlife habitat and            include maintaining a small clearing along the shore for picnic
             control nuisance and non-native species of vegetation may be               tables, benches, and recreational craft (dinghies, canoes, (Jay
             allowed. Homeowner control of pest species of vegetation                   sailboats, etc.). Additionally, the CRMC may allow small,
             such as European bittersweet and nuisance species such as                  non-habitable structures including storage sheds, boat houses
             poison ivy is normally considered acceptable. However, the                 and gazebos within Coastal Buffer Zones, where appropriate.
             indiscriminate use of herbicides or the clear-cutting of                   However, these structures may be prohibited in sensitive or
             vegetation shall be prohibited. The use of fertilizers is                  critical habitat areas. Due to the potential for these structures
             generally prohibited within the Coastal Buffer Zone except                 to impact values provided by Coastal Buffer Zones, the
             when used to enhance the replanting of native vegetation (e.g.,            Council shall exercise significant discretion in this area.
             hydro-seeding) approved by the Council. However, the
             clearing or outright elimination of natural vegetation for such
             purposes as controlling ticks or pollen shall not be permitted.





































             68











                                                                                             B. Management options within coastal buffer zones:
                Appendix B
                Rhode Island Coastal Buffer                                                  1. Shoreline Access Paths - Pathways which provide
                                                                                         access to the shoreline are normally considered appropriate.
                Zone Management Guidance                                                 Pathways may be 6' wide or less and follow a winding, but
                                                                                         direct path that does not promote erosion within the buffer
                                                                                         zone. Shoreline access paths must be designed to minimize
                     Revised January 7, 1994                                             disturbance and may be prohibited in sensitive habitat areas,
                                                                                         including but not limited to, coastal wetlands. Pathways may
                     CRMC Coastal Buffer Zone Management Guidance                        be vegetated with grasses and mowed or may be surfaced with
                                                                                         crushed stone or mulch. Fertilizers may only be allowed for
                     A. Guidelines for preparing an application for Coastal              the initial establishment of grassed pathways. Proper site
                Buffer Zone Management:                                                  plans must be submitted which show the location of the
                                                                                         proposed path through the buffer zone. Applicants may also
                     1. All proposals for buffer zone management must be                 be required to delineate the path on site for CRMC staff
                designed with respect to the one or more of the "Management              inspection.
                Options" identified in Section "B" of these guidelines and                   2. View Corridors - Selective tree removal and pruning
                must utilize appropriate techniques for managing vegetation as           and thinning of natural vegetation may be allowed within a
                defined in Section "C".                                                  defined corridor in order to promote a view of the shoreline.
                     2. Photographs and site plans must be submitted for all             Only the minimal alteration of vegetation necessary to obtain a
                applications in order to minimize the need for on-site inspec-           view shall be considered acceptable (clear cutting is not
                tions. Actual field inspections will only be performed when              allowed). Shoreline access paths (if proposed) should be
                deemed necessary by CRMC staff. All applications should be               located within a view corridor to minimize disturbance within
                complete, clear and concise. Applications which are unclear or           the buffer. Applicants proposing a view corr idor must prepare
                imprecise will be returned.                                              a plan showing the view corridor's location within the Coastal
                                                                                         Buffer Zone with respect to view points from a dwelling or
                     3. Applications which propose acceptable alterations                other viewing area. View corridors are typically trapezoidal in
                within Coastal Buffer Zones (as determined by CRMC staff)                shape, being narrow at the inland edge and expanding toward
                will be processed as a "Category "A" and will receive                    the shore. On residential lots of 2 acres or less, only one view
                administrative approval. In cases where CRMC staff deter-                corridor is typically considered acceptable. View Corr idors
                mines the application to be unacceptable, an effort will be              may not affect more than 25 % of the length of the Coastal
                made to negotiate a resolution with the applicant. If a                  Buffer Zone as measured along the shoreline feature. View
                favorable resolution cannot be reached, CRMC staff will make             Corridors may be prohibited in sensitive or critical habitat
                a recommendation to the Executive Director that the applica-             areas.
                tion be processed as a Category "B" review requiring final                   3. Habitat Management - The management of natural
                decision by the full Coastal Council.                                    vegetation within a Coastal Buffer Zone to either enhance
                     4. All proposals for Coastal Buffer Zone management                 wildlife habitat or control nuisance and/or non-native species
                should involve minor alterations which do not depreciate the             of vegetation may be allowed where it is demonstrated that the
                values and functions of Coastal Buffer Zones as defined by               existing environmental conditions will be improved for native
                Section 150 of the RICRMP. At a minimum, at least sixty                  plantlife and wildlife. Additionally, homeowner control of
                (60%) of a buffer zone shall remain completely unaltered.                nuisance species of vegetation such as European Bittersweet
                Typically, Coastal Buffer Zone Management Plans which                    and poison ivy are considered acceptable within managed
                affect 25% or less of a buffer zone are more likely to be                portions of Coastal Buffer Zones. However, the indiscrimi-
                approved. Areas to remain unaltered should be clearly                    nate use of herbicides is prohibited and fertilizers may only be
                identified on the pfoposed plans. An exception to this                   used to enhance the replanting of native vegetation. In
                requirement is allowed for "Suburban Coastal Buffer                      addition, maintaining a buffer zone in a "landscaped condi-
                Zones" - see Section B.6 of this Guidance material.                      tion", or establishing lawn are not considered appropriate
                                                                                         habitat management activities and are prohibited. In Coastal
                     5. Where appropriate, Coastal Buffer Zone management                Buffer Zones encompassing one acre or more, clearing may
                  ay be applied to Coastal Banks. However, the CRMC may                  be allowed to establish field conditions which contain native
                impose greater restrictions on alterations affecting coastal             grasses and herbaceous plants. In such cases, clearing for
                hanks.                                                                   field establishment shall not affect more than 25% of the
                                                                                         Coastal Buffer Zone. All Buffer Zone Management plans
                     6. Tree damage and removal - in cases where a small                 involving habitat management within a Coastal Buffer Zone of
                number of dead, diseased, or storm damaged trees need to be              one acre or more, or in sensitive or critical habitat areas (as
                removed from a buffer zone, the applicant may request an                 determined by CRMC staff) shall submit a buffer zone
                expedited review. In such cases, a description of work and a             management plan prepared by a qualified environmental
                photograph of the area may be sufficient for CRMC review.                professional or biologist.


                                                                                                                                                           69











                 4.  Safety and Welfare - Selective tree removal and                         2. Selective Pruning - Pruning as defined for CRMC
            pruning and thinning of natural vegetation within a Coastal                 purposes involves cutting branches from trees, tree saplings
            Buffer Zone may be allowed on a case-by-case basis for                      and shrubs. For certain Coastal Buffer Zone Management
            proven safety and welfare concerns (e.g., removal of a                      options, pruning the tops of shrubs and forest undergrowth
            damaged or diseased tree in close proximity to a dwelling).           In    (topping) may be appropriate to discourage growth in height.
            order to promote child safety and manage pets in areas                      On level ground, shrubs and forest undergrowth should be
            harboring ticks, fences along the inland edge of a Coastal                  pruned to a height of not less than 4'-5'. In areas where the
            Buffer Zone and along shoreline.access paths or shoreline                   ground surface descends toward the shoreline, topping should
            recreation areas may be permitted (fences must be of an                     only be perfonned to a height that allows a view of the water.
            "open" type construction to permit the passage of wildlife, e.g,            Applicants proposing pruning must describe in detail the work
            split rail or similar). Coastal Buffer Zone management plans                proposed, provide photographs and a'site plan, and/or mark
            shall include methods of avoiding problem areas such as the                 -those portions of the Coastal Buffer Zone where vegetation
            proper placement and maintenance of paths.                                  will be pruned on-site. The species of vegetation to be pruned
                                                                                        should be identified since some species of vegetation cannot
                 5. Shoreline Recreation - The CRMC recognizes that                     tolerate excessive pruning or topping. Selective pruning is
            shoreline recreation is one of the predominant attractions for              often a preferred technique for the establishment of a view
            living on, or visiting the Rhode Island coast. In order to allow            corridor.
            for. such uses, minor alterations of Coastal Buffer Zones may
            be permitted along the shoreline if they are determined to be                    3. Selective Thinn       - Thinning as defined for CRMC
            consistent with CRMC's goals and policies as noted in the                   purposes involves the selective removal of tree saplings,
            Rhode Island Coastal Resources Management Program (RI                       shrubs and vines occurring in brush areas and in the under@
            CRMP). Appropriate alterations typically include maintaining                growth of forested buffer zones. Applicants proposing
            a small clearing along the shore for picnic tables, benches, and            thinning must describe in detail the work proposed, provide
            recreational craft (dinghies, canoes, day sailboats, etc.).                 photographs And a site plan, and/or mark areas to be thinned
            Additionally, where appropriate, the CRMC may allow small                   on-site. The species of vegetation to be removed from a
            (200 sq. ft. total floor space, or less), non-habitable structures          Coastal Buffer Zone man     -agement area must be differentiated
            including storage sheds, boat houses, and gazebos within                    from those species which are to be retained and encouraged.
            Coastal Buffer Zones. Due to the potential for these structures             Selective thinning is often a'preferred technique in areas
            to impact natural values provided by Coastal Buffer Zones,,the              where habitat management will be performed.
            Council shall exercise significant discretion in this area.
                                                                                             4. Restorative Planjing - For purposes of Coastal Buffer
                 6. Suburban Coastal Buffer Zones - Where the Coastal                   Zone Management, restorative planting shall be strictly
            Buffer Zone requirement is 25' or less (as per RICRMP                       defined as the planting or replanting of natural vegetation
            Section 150, Table 2a), the CRMC shall consider such buffer                 native to the Rhode Island shoreline. However, naturalized
            zones "Suburban Coastal Buffer Zones". Suburban Coastal                     species such as Rugosa Rose may be allowed, as determined
            Buffer Zones may be managed in their entirety (100%) by                     by CRMC staff. The planting of non-native, landscape and
            selective tree removal, s  'elective pruning, selective thinning            exotic species, in most cases, shall not be considered appropri-
            and restorative planting. However, the CRMC may require                     ate in Coastal Buffer Zones.
            thatseveral trees be maintained or planted to protect scenic
            quality.                                                                         5. Mowing - In most cases, mowing of vegetation within
                                                                                        a Coastal Buffer Zone shall be prohibited unless associated
                                                                                        with the establishment and maintenance of shoreline access
                 C. Appropriate techniquesfor managing vegetation                       path or approved shoreline recreation area. However, for
            within a coastal buffer zone:                                               certain habitat management options, annual or biannual
                                                                                        mowing may be allowed to maintain field vegetation where
                 1. Selective Tree Removal - In cases where the applicant               such vegetation is considered valuable to wildlife and other
            wishes to remove a few select trees, trees proposed to be cut               natural values. In such cases, mowing shall be confined to
            must be specifically identified for CRMC staff review. In                   25% of the Coastal Buffer Zone area, or less.,
            most cases, photographs of the buffer area may be sufficient
            provided-the affected trees are clearly shown in relation to the                 6. Clearing - Clearing or clear-cutting of vegetation
            surrounding buffer and shoreline. Trees may also be marked                  within a Coastal Buffer Zone shall only be allowed for the
            on-site to allow inspection by CRMC staff. In order to                      establishment of shoreline access paths, shoreline recreation
            minimize disturbance and allow monitoring by CRMC staff,                    areas and in certain cases, habitat management options which
            tree stumps of fallen trees shall not be removed. CRMC staff                are designed to maintain a field of native grasses and herba-
            may make a follow-up inspection to verify that only marked                  ceous plants. Clearing shall not affect more than 25% of the
            trees were cut based upon stump counts. Should the applicant                Coastal Buffer Zone area. Clearing for habitat management
            wish to remove a fallen tree from the buffer zone, this must be             shall not be allowed in Coastal Buffer Zones of less than one
            performed in a manner which does not disturb remaining                      acre.
            vegetation. Selective tree removal is often a preferred
            technique for the establishment of a view corridor.



            10











                   7. Filling and grading - Minor filling (10 cubic yards or
              less) and grading shall only be allowed in Coastal Buffer Zone
              areas for the establishment of shoreline access paths and
              shoreline recreation areas. Certain minor cutting and filling
              activities may also be allowed on a case-by-case basis to
              promote these uses. Filling and grading shall not be allowed
              for habitat management options,


                                 Figure 10. Example of an adequate buffer,zone management plan drawn by owner.


                                    - View corridor to be maintained by pruning bruï¿½h to a height of 4-5'

                                    - View corridor at shore 507200' of buffer length at coastal feature 25%









                                                                  River Road





                                                                    Driveway




                                                                         Dwelling









                                                                         40'

                                                                        View                                       100'setback
                                                                        Corridor

                                                                           6'wide         Buffer area
                                             Buffer area                   path           to remain                75'buffer
                                             to remain                                    undisturbed
                                             undisturbed                 F-I       O'x 10' gazebo
                                                                           50'                                     200' buffer
                                                                                                                   length at
                                                                                                                   coastal wetland

                                                            Edge of wetland


                                             W







                                                           Edge of Narrow River



                                                                                                                                                   71





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