    [From the U.S. Government Printing Office, www.gpo.gov]

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                 CIO                     THE BUFFER AREA STUDY
                                                   by

                                    Raymond Palfrey and Earl Bradley

                                       Coastal Resources Division

                                        Tidewater Administration

                                Maryland Department of Natural Resources

                   The production of this report was made possible with funding provided

              to Maryland's Coastal Zone Management Program from the Office of Coastal

              Zone Management, NOAA.

                                                    TABLE OF CONTENTS

                                                                                                  Page

                     INTRODUCTION  ..........................................................      1

                     THE USE OF BUFFER AREAS FOR SEDIMENT CONTROL

                          Introduction .....................................................       2

                          The Effectiveness of Buffer Areas for Sediment Control      ...........  3

                          Variables Which Affect the Efficiency of Buffer Areas      ............  4

                     THE USE OF BUFFER AREAS TO REDUCE STORMWATER RUNOFF

                          Introduction .....................................................       8

                          The Effectiveness of Vegetative Buffers for Reducing

                               Stormwater Runoff   ...........................................     9

                     THE USE OF BUFFER AREAS AS NUTRIENT FILTERS

                          Introduction .....................................................      11

                          The Effectiveness of Buffer Areas as Nutrient Filters

                               for Subsurface Runoff    .......................................   13

                     THE USE OF BUFFER .'-,::AS TO MODERATE STREAM WATER TEMPERATURES

                          Introduction .....................................................      14

                          The Effectiveness of Buffer Areas in Moderating Stream

                               Temperaturf,3  ................................................    15

                     THE VALUE OF BUFFER AREAS AS FOOD SOURCES     .............................  18

                     THE VALUE OF BUFFER AREAS AS TRANSITION ZONES     .........................  19

                     ESTABLISHING BUFFER AREAS

                          Methods That Have Been Used in Establishing Buffers      .............. 20

                          Recommendations for Establishing Buffer Areas     ....................  25

                     FOOTNOTES  .............................................................     27

                     BIBLIOGRAPHY  ...........................................................    30

                                               INTRODUCTION

                    Buffer areas are zones of undeveloped vegetated land extending from

               the banks or high water mark of a watercourse 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 uses

                    This report reviews these potentially detrimental impacts and notes

               how buffer areas have been shown to negate or reduce those impacts.

               Relevant literature documenting these positive functions of buffer areas is

               cited, and information is presented regarding the environmental factors

               which determine how effectively buffer areas function. This report

               concludes with recommendations regarding the establishment of buffer areas

               in the State of Maryland.

                                      THE USE OF BUFFER AREAS FOR SEDIMENT CONTROL

                     Introduction

                                Falling raindrops, by virtue of their mass and velocity of
                                falling, possess tremendous amounts of kinetic energy. When
                                they strike the earth's surface, this energy can dislodge
                                and mobilize soil particles, initiating erosion."I

                          Once dislodged, the soil particles splashed downhill travel farther

                     than those splashed uphill thus causing a net downhill movement of soil.

                     This process is called "rainsplash erosion." In areas where the rate of

                     rainfall exceeds the soils capacity to absorb it, water accumulates and

                     runs downhill, carrying dislodged soil particles with it in an irregular

                     sheet. The force of this movement of water can dislodge more soil

                     particles. This type of erosion is called "sheetwash erosion." When the

                     soil eroded by both rainsplash and sheetwash erosion is carried to a

                     receiving watercourse or water body, it becomes sediment in the receiving
                     waters-2

                          Recent studies in the Black Creek Watershed in Indiana have shown that

                     while surface runoff accounted for only fifty percent of the total water

                     loss in that agricultural watershed, it accounted for ninety-nine percelit
                     of the sediment lost.3 Thus, it can be concluded that adequate treatment

                     of surface runoff can control sediment inputs into watercourses or water

                     bodies.

                          Sediment by weight, is the largest single pollutant of water resources
                     in the nation.4 When it enters water bodies or watercourses, it reduces

                     the productivity of aquatic plant, invertebrate, and vertebrate communi-
                     ties.5 High concentrations of sediment have detrimental effects on

                     invertebrates such as crayfish and rooted aquatic plants. Very high

                     concentrations-greater than 20,000 parts per million (ppm)-can cause

                                                           2

               mortality in fish by clogging their gills. While such high concentrations

               are rarely found in watercourses, lesser amounts threaten the survival of

               fish by covering essential spawning grounds, smothering their eggs, and

               preventing the emergence of recently hatched fry. Sedimentation has been

               cited as one of the major causes of the decline in quality of fisheries
               throughout the United States-6

                   The significant proportion of invertebrate species which spend the

               majority of their lives in the bottom substrate are further impacted by
               sediment because it reduces substrate types.7 This inevitably -leads to

               the elimination of some invertebrate species and an overall reduction in

               the total invertebrate population.

                    In studies in Maryland, silt deposition of 2 millimeters (mm) was

               found to cause 100% mortality in white perch eggs with sediment thickness

               of .5-1 mm causing mortalities in excess of 50%. In addition, turbidity in

               excess of 100 ppm was found to greatly inhibit fish growth and reproduc-

               tion.8

               The Effectiveness of Buffer Areas for Sediment Control

                    Vegetative buffers can reduce both sediment generation and sediment

               transport. Reduction in sediment is accomplished both by vegetative cover

               reducing the impact of falling rain and by roots binding soil particles

               together. It has been noted that a thick cover of vegetation intercepts

               virtually all the kinetic energy of rainfall thus reducing sediment

               generation. Thus, grading of development sites should be kept to a

               minimum. With respect LQ sediment transport, studies in agricultural and

               forested watersheds have shown that the maintenance of vegetated buffer

               areas adjacent to watercourses and water bodies can inhibit the transport

               of sediment to these water resources. In a 1974 study in the Black Creek

                                                  3

                    Watershed in Indiana, Mannering and Johnson passed water containing

                    sediment through a 15 meter (49.2 foot) strip of bluegrass sod. In a

                    single trial, they determined that 45% of the sediment was removed from the
                    water.9 In a similar study in the Black Creek Watershed, tests utilizing

                    a rainulator showed that a 50-foot strip of bluegrass sod removed 46% of
                    the sedimentation in water flowing from a test plot.10 Stanley Wong and

                    Richard McCuen, in a report produced as part of a study on appropriate

                    stormwater management methods in coastal areas, funded by Maryland's

                    Coastal Zone Management Program, developed a mathematical model to

                    determine the effectiveness of buffer strips for sediment control. In the

                    application of the model to a 47 acre watershed, the use of a 150 foot

                    buffer strip with a 3% slope was found to reduce sediment transport by

                    90%.11

                    Variables Which Affect the Efficiency of Buffer Areas

                          The type of vegetation present has been cited as an important factor

                    in determining the u.'fectiveness of buffer areas as sediment filters. In a

                    study of the efficiency of vegetative filters to trap sediment in open

                    channels, cited by James Karr and Issac Schlosser in "The Impact of Near-

                    stream Vegetation anc Stream Morphology on Water Quality and Stream Biota,"

                    coastal and common bermuda grass were found to be the most efficient

                    species of vegetation for sediment filtration. Their effectiveness.for

                    removing sediment is noted in the following table:

                                                         TABLE 1

                                  PERCENT REP,jVAL OF SEDIMENT AFTER VARYING LENGTHS
                                          OF FILTRATION THROUGH BERMUDA GRASS

                                                               Distance Filtered (Meters)
                    Grass Species                               90         215         300

                    Common Bermuda                             50.0        90.4        97.0
                    Coastal Bermuda                            55.5        97.5        98.5

                                                          4

                    It is further noted that grasses used as vegetation filters should

               have the following characteristics;

                    1.   Deep root system to resist scouring in swift currents

                    2.   Dense, well branched top growth

                    3.   Resistance to flooding

                    4.   Ability to recover growth subsequent to inundation by
               flooding-13

                    While the efficiency to buffer areas as sediment filters varies with

               vegetative type, and increases as the width of the vegetated filter

               increases, this increase is a decreasing exponential function. Stated more

               simply, the percentage of sediment removed by vegetation increases with the

               width of the buffer area, but at smaller increments as buffer size is

               increased.

                    In addition to width and type of vegetation present in the buffer

               area, a number of other variables affect the efficiency of buffer areas as

               sediment filters. 1,.e slope of the vegetated buffer area affects the

               efficiency of the buffer area in a direct manner. As slope increases, the

               velocity of surface runoff increases, which increases its ability to

               transport sediment. "his means that when buffer areas are established in

               sloping areas, the width of the buffer must be increased to compensate for

               slope. Trimble and Schwartz developed the following recommendations as to

               how wide filter strips (or buffer areas) between logging roads and streams

               should be in municipal watersheds given sloping conditions. (It should be

               noted that logging roads 4ere analyzed by Trimble and Schwartz in their

               study of sedimentation in forested areas because they are a significant

               generator of sediment in forestry operations).

                         "Starting with a strip 50 feet wide on level land, the width
                         should increase 4 feet for each 1 percent increase in slope."14

                                                      5

                         While there is a general consensus in the literature that slope
                    affects the efficiency of buffer areas, Rodgers, Syz, and Golden state that
                    slopes greater than 10 percent are too steep to allow any significant
                    detention of runoff and sediment. When such slopes occur next to aquatic
                    resources, according to these authors, they should "be carefully managed,

                    kept covered with vegetation and considered part of the buffer zone."15

                         The height of vegetation in the buffer area also affects its

                    efficiency as a sediment filter. Taller grasses are reported as having
                    higher retardance coefficients than shorter species. Therefore, grasses in
                    buffer areas should not be cut. If they are cut and flow rates are high

                    enough to submerge the grass, their efficiency as a filter declines to

                    zero.

                         Other factors which affect the efficiency of vegetated buffer areas

                    include: the ability of the soil in the buffer to absorb water, size
                    distribution of incoming sediment, and rate runoff. McCuen and Wong in

                    their report on the Desk& of Vegetative BufferStrips for Runoff and

                    Sediment Control have undertaken the most comprehensive analysis of the

                    relationship among these variables in affecting the efficiency of buffer

                    strips.

                        Figure 1 shows uhe graphical relationship they developed between trap
                    efficiency (Tr), % slope, runoff velocity, effective buffer strip length,

                    and Manning's roughness coefficient of the vegetation (n).

                                                       6

         14-

         13-

         12-

         1 1-
         10-  (forest)
          9-  n:0.80       (dense                               1500
                           turf)
       LU 8-              n:0.35      (light
       CL                             turf )
       0  7-                          n:0.20                   -1400
       _j 6-
       W
          5-                                                   - 1300

          4-

          3-                                                   -1200

          2---
                                                                      m
                                                                1 100
                              ITR:99%
          0                                                           m
                                                         TR:95%
                                                               - 1000
                                                                      <
                                                                      rn

                                                               - 900  C3
                                                                      c
                                                                        n
                                                                      -n
                                                               -800   m

                                                                      CD
                                                               - 700  -4

                                                               - 600
                                                        TR:90%        m

                                                                Soo
                                                                      X

                                                                40,0

                                                        TR:85%
                                                        .R:80%  300
                                                    ZT,

                                                                200

                                                     Trt :7 5 % 100

                       0.33         0.67         1.00         1.33

                        RUNOFF VELOCITY (ft/sec)
                                   Fig
                                     _,urf, 1
                                             7

                                THE USE OF BUFFER AREAS TO REDUCE STORMWATER RUNOFF

                   Introduction

                        In addition to reducing sediment transport vegetated buffer areas also

                   reduce the total volume of surface runoff. This is because the vegetation

                   in the Buffer area retards the flow of surface runoff and allows the soil

                   to absorb much of it. The soil then goes on yielding this water to the

                   watercourse or water body over an extended period of time.

                        U.S. Department of Agriculture studies in Wisconsin have shown that
                   runoff from grasses is one-fifth of that from continuous row crops.16

                   Rotations with grain and hay had intermediate sediment delivery ratios.

                   The reserchers in these studies concluded that runoff is inversely related

                   to the density of vegetation. When runoff volumes from forested watersheds

                   are compared to areas under intense cultivation, the differences are even

                   greater. Runoff from intensely cultivated agricultural land may be as much
                   as forty times thac uf forested land.17

                        Hewlett and Nutter have shown that in watersheds in a natural

                   condition surface runoff is rare.18 The natural vegetation in the

                   watershed impedes tht flow of runoff and allows it to percolate into the

                   ground. The water is then passed through a soil filter before it reaches a

                   watercourse or water body. Trees, in particular, facilitate this process,

                   since their roots penetrate deep into the ground, aerating the soil and

                   improving its porosity. Their litter and humus also add to the ability of

                   other vegetation to retard runoff. Overall, this process results in a more

                   gradual release of water from the watershed and provides for more stable

                   watercourses and aquatic environments.

                        On lands which are not covered by vegetation or which are only par-

                   tially covered, flooding and seasonal shortages of water are more common.

                                                      8

               This leads to the conclusion that the establishment of buffer areas

               adjacent to watercourses and water bodies not only reduces sediment and

               nutrient transport and moderates water temperatures, but reduces total

               runoff volumes, the possibility of flooding, and seasonal shortages of

               water as well.

                    It should be noted that buffer areas provide additional protection

               from flooding by providing a margin of safety between watercourses and

               water bodies and development. Natural processes and changes caused by man

               often alter hydrology by increasing peak flows. These peak flows can in

               turn change stream geometry. If such changes become radical., flooding and

               erosion hazards may result. Buffer areas provide safety from these hazards

               by providing space between watercourses or water bodies and development.

               The Effectiveness of Vegetative Buffers for Reducing Stormwater Runoff

                    In their paper on "The Design of Vegetative Buffer Strips for Runoff

               and Sediment Control," Wong and McCuen note that:

                         "Buffer s1rips have not received the attention they
                         deserve as a means of controlling stormwater runoff
                         because they have not been viewed as a viable
                         alternative to the detention basin. Design methods
                         have not been previously developed that can account
                         for the effects of buffer strips on runoff volumes
                         and sedimert loadings. However, it seems reasonable
                         that the tital volume of detention storage that is
                         required to mitigate the effects.of development could
                         be reduced if properly designed and located buffer
                         strips were used to reduce runoff volumes and sediment
                         loadings into the detention facility."19

                    They further note that the reduction in the runoff volume occurs as

               the vegetation impedes and retards the flow of water, allowing a portion

               of it to infiltrate the soil. The rate of infiltration is a function of:

               1) the condition of the vegetative cover, 2) the properties of the under-

               lying soil, 3) the rainfall intensity, and 4) antecedent soil conditions.

               These factors act in an interrelated manner to influence the amount of

               water that infiltrates a buffer strip.

                                                   91

                         In their analysis of a 47 acre watershed in Maryland, they noted that
                   the location of a 150 ft. buffer strip above the inlet to a detention

                   structure would result in a reduction of runoff volumes of 10 observed

                   Storms of 28%. The reduction of runoff into the detention basin is

                   greatest for the smallest storm event and, in general, the total volume
                   loss will increase when the duration of the runoff is longer.20

                                                      10

                               THE USE OF BUFFER AREAS AS NUTRIENT FILTERS

               Introduction

                   One of the major causes of excess nutrient enrichment, or eutrophi-

               cation, is the transport of phosphorus and nitrogen from fertilized

               agricultural lands to watercourses or water bodies by surface and substance

               runoff. Nutrients, in the right proportions, are not harmful to water

               resources. In fact, they are essential to the normal life processes of

               aquatic plants and animals. Under normal conditions, they are supplied by

               decaying organic matter in or near watercourse or water bodies and provide

               for a highly productive aquatic environment. Water quality problems only

               arise when too many nutrients are introduced into the aquatic environment.

                    Excess nutrient enrichment causes the acceleration of plant growth,

               partially phytoplankton and algae. This leads to large algal plankton

               blooms which cause water quality problems including noxious odors and toxic

               metabolic byproducts. This over-production can also block the light

               required by desirable aquatic plants for normal growth. While phyto-

               plankton and algae normally produce oxygen, under conditions of accelerated

               growth they consume ore oxygen than they produce. This situation can

               cause a shortage of dissolved oxygen. Aggravating this situation is the

               fact that these plants have extremely short life spans. This causes a

               further depletion of dissolved oxygen, since large amounts of dissolved

               oxygen are used during the decomposition of the dead plants. Maintenance

               of a moderately high dissolved oxygen content is necessary for the mainte-

               nance of healthy aquatic systems.

               The Effectiveness of Buffer Areas as Nutrient Filters for Surface Runoff

                    In studies in the Black Creek watershed, 88 percent of all nitrogen

               and 96 percent of all phosphorous reaching watercourses or water bodies as

                                                  11

                    surface runoff in agricultural watersheds was found to be attached to
                    sediment particles.21 As previously noted, data from field and labora-

                    tory studies indicate that vegetation effectively removes sediment from

                    surface flows. Hence, the removal of nutrients attached to sediment

                    particles can be accomplished by the filtering of surface runoff through

                    vegetated buffer areas.

                        In the same study, when fertilizers were applied to agricultural land,

                    slightly higher proportions of phosphorous and nitrogen were found in

                    solution in surface runoff and less attached to sediment. Under this

                    condition, an average of 92 percent of phosphorous and 72 perceriz of
                    nitrogen was attached to particles.22 Past efforts to use vegetation to

                    remove the smaller percentage of nutrients which are carried in solution in

                    surface runoff have yielded conflicting results. Reductions of nitrogen

                    and phosphorous as high as 80 percent respectively have been reported using
                    a 90 meter sod filter strip with a slope of 12 percent.23 Lows of 4

                    percent nitrogen reduction and 6 percent phosphorous reduction have been

                    reported in an experiment using a 300 meter vegetated filter strip to
                    remove nutrients from municipal effluent.24 James Karr and Issac

                    Schlosser in "Impact )f Nearstream Vegetation and Stream Morphology on

                    Water Quality and Stream Biota" conclude that the reasons for these extreme

                    variations in nutrients removal are difficult to determine due to poorly

                    controlled or unreported experimental conditions. However, four factors

                    were identified as likely to be important to the success in removing

                    nutrients in solution from surface runoff: detention time (related to

                    slope of filter), type of vegetation, volume of water treated, and soil
                    type.25

                        The literature therefore supports the conclusion that the maintenance

                    of vegetated buffer areas adjacent to watercourses or water bodies can

                                                      12

               significantly improve water quality by filtering nutrients from surface

               runoff, although the degree of improvement is difficult to quantify.

               The Effectiveness of Buffer Areas as Nutirent Filters for Subsurface

               Runoff

                    Most of the research undertaken on nutrient enhancement has con-

               centrated on surface flows rather than on subsurface flows. Studies on

               watersheds in the Rhode River area in Anne Arundel County indicate that

               nutrients in subsurface runoff may contribute to nutrient enrichment, and

               that forested buffer areas may sificantly reduce the amount of nutrients in
               subsurface flows-26 Research has also been undertaken on effluent runoff

               from septic tanks. Factors such as soil permeability, groundwater level,

               stratigraphy, distribution of soil types, and slopes were found to be

               particularly important to safe use of septic tanks. If there is an

               inadequate distance between the septic tank and water body, contamination

               of the water may occur, with nitrates which are particularly mobile in

               groundwater likely o be the cause of most estuarine entrophication. As

               noted in Coastal Ecosystem Management by John Clark, the setback presently

               required for septic systems, typically 50 feet, which may be adequate to

               remove pathogens is r3t adequate for the removal of certain dissolved

               pollutants, particularly nitrates. In many urbanized areas, estuarine

               bodies have become eutrophic and degraded from septic tank leachates and

               overflow. Clark cites studies that have shown high concentrations of

               nitrates at distances of 100 feet from septic systems with unacceptable

               levels remaining at 150 IL'eet. He therefore recommends that a 300 ft.

               setback be used whenever possible, with 150 feet the minimum setback con-
               sidered to be adequate to avoid nitrate pollution.27

                                                   13

                              THE USE OF BUFFER AREAS TO MODERATE STREAM WATER TEMPERATURES

                     Introduction

                           Temperature is very important in determining water quality as the
                     table below indicates. As a water temperature increases, the capacity of
                     water to hold oxygen decreases.28

                                      RELATIONSHIP BETWEEN TEMPERATURE AND MAXIMUM
                                          DISSOLVED OXYGEN CONCENTRATION IN WATER

                                TemDerature                Maximum Oxygen Concentration (ppm)

                                      0                                    14.6
                                     10                                    11.3
                                     20                                    10.7
                                     30                                      7.6

                          Since oxygen is utilized in the decomposition of organic matter,

                     elevated water temperatures reduce the ability of streams to assimilate
                     organic wastes without oxygen depletion.29

                          Even more important to water quality is the effect of temperature on

                     the release of nutri-ents attached to sediment particles. As water

                     temperature increases, the rate at which nutrients attached to sediment

                     particles are released and thus become soluable increases.30 These

                     nutrients are then ir a more readily available form. Data from Sommers,

                     Nelson, and Kamisky indicates that an exponential increase in phosphorous
                     release occurs with increases in temperature.31 Slight increases in

                     temperature above 150C were shown to produce substantial increases in the

                     amount of phosphorous released.

                          The previously citea information indicates that the removal of the

                     vegetation which shades streams will cause several detrimental effects.

                     During the summer months, average temperatures will be higher which will

                     reduce the ability of streams to hold oxygen and cause the release of more

                     nutrients from the sediment particles to which they are attached.

                                                           14

               Increasingly large blooms of nuisance algae will result because of elevated

               nutrient concentrations, temperatures, and light availability. The net
               effect of these changes will be decreases in water quality and the quality

               of biotic communities.

                    Changes in temperature can also cause shifts in the aquatic community.
               Temperature increases of 6-90C can make it energetically impossible for

               some species to continue living in the aquatic environment. In fact, an

               overall shift can occur in the aquatic community because of temperature

               increases,, with more desirable species replaced by less desirable species
               more tolerant of increased temperatures.32

                    Headwater streams, which are very important as the breeding grounds

               for many valuable species of sport and commercial fish, are particularly

               vunerable to increases in temperature when nearstream vegetation is

               removed. The maintenance of continuous vegetated buffer areas adjacent to

               these streams is very important to their biological productivity.

               The Effectiveness oi Buifer Areas in Moderating Stream Temperatures

                    A number of studies have shown that the maintenance of nearstream

               vegetation moderates stream temperatures. The results of some of these

               studies are summarizel below.

                    G.F. Green compared the temperatures of a stream flowing through

               farmland to a stream flowing through a hardwood forest over a one year

               period. The maximum weekly temperature of the farm stream, which was not

               bordered by vegetation, ranged from 50 to 12.80C above the maximum

               weekly temperatures of tne forest stream during the warmer months. During

               the coldest months, the temperature of the forest stream was frequently as
               high as 3-90C above the farm stream-33 Similar effects were recorded

               in a study of a single stream, before and after vegetation was removed.22

                                                   15

                    These studies indicated that nearstream vegetation protects streams from

                    temperature extremes in both summer and winter.

                         In a more detailed study of stream temperatures conducted in the

                    Appalachian Mountains by L. W. Swift and J. E. Messer, it was shown that

                    temperature minimums during the warmest months also increased for streams
                    not bordered by vegetation.35 This indicates that the temperatures of

                    these streams did not decrease significantly during the night. Such

                    prolonged periods of elevated temperatures can have significant impacts on

                    the energy budget of the aquatic ecosystem, causing major alterations in

                    the biotic community. Swift and Messer also showed that if nearstream

                    vegetation was left to shade a stream, while the remainder of the forest
                    was cleared out, only minor changes in stream temperatures would occur-36

                    These findings support the conclusion that if vegetated buffer areas are

                    maintained adjacent to streams, significant decreases in stream

                    temperatures will result.

                         A more recent -aaly6is of the use of buffer areas by G.W. Brown and
                    J-R. Brazier supports the above conclusion.35 After examining various

                    streams and types of buffers, they concluded that angular canopy density (a

                    measure of the abilifl of vegetation to provide shading) is the only buffer

                    area parameter strongly correlated with temperture control. Buffer area

                    width was found to be related to the effectiveness of the buffer area to

                    moderate stream temperatures through a complex interrelationship of canopy

                    density, canopy height, stream width and stream discharge.

                         The study recommena.,-d that the angular canopy density be kept at least

                    at 80% coverage. It further concluded that for the average buffer strip

                    composed largely of trees, the maximum angular canopy density and hence the

                    maximum shading ability is reached within a width of 80 feet, with 90% of

                    the maximum reached within 55 feet.

                                                         16

                     The study also showed that the effectiveness of buffer areas on

               temperature control increased as stream size decreased. This is generally

               beneficial in terms of water quality, since small streams tend to have the

               greatest temperature control problems. The study also showed that if

               temperatures are controlled in the upper reaches of drainage basins,

               temperature problems in downstream areas, including reservoirs, will be

               controlled as well.

                                                    17

                                    THE VALUE OF BUFFER AREAS AS FOOD SOURCES

                        The input of leaves and twigs from nearstream vegetation is a very

                    important food source for aquatic organisms, particularly in headwater
                    streams.36 In these watercourses, the microflora which cover leaves and

                    twigs provide the majority of the energy utilized by invertebrates. These

                    invertebrates are at the base of the aquatic food chain headed by predator

                    fish. If nearstream vegetation is removed and vegetated buffer areas are

                    not preserved along the banks of watercourses, the energy budget and,

                    hence, the aquatic structure, will be negatively impacted.

                                                        18

                             THE VALUE OF BUFFER AREAS AS TRANSITION ZONES

                   The edge of wetlands includes a transitional zone between the wetland

              and adjacent uplands which should be preserved to maintain the health of
              the wetlands. This zone exhibits great variety in soils, terrain, and
              hydrology resulting in a tremendous variety of plant species. This array
              of plant species provides food and cover for large numbers of wildlife

              species. The zone serves many functions crucial to wildlife. It provides
              food, cover, travel routes, roosting sites, nesting sites, and denning

              sites. It is crucial to the ecology of the wetlands.

                   Cultivation, grazing, construction and other impacts within the

              wetland edge lead to increased surface runoff and erosion into the wetland.

              This results in siltation which chokes out wetland plants and reduces the

              size of the wetland. The surface runoff can increase nutrient loading by

              carrying fertilizers, domestic animal and human wastes, detergents and dead

              vegetation into the wetiand. It can also carry toxic substances such as

              road salts, petroleum wastes, herbicides, pesticides and industrial wastes

              into the wetlands. These pollutants reduce water quality and negatively

              impact the aquatic pl-ints and animals of the wetlands. This in turn

              affects the wildlife dependent on these organisms as food sources. Thus,

              while the immediate effect of disturbances in the wetland edge is felt by

              wildlife directly dependent on that zone, in time the effect will be felt
              throughout the wetland.39

                                                  19

                                              ESTABLISHING BUFFER AREAS

                    Methods That Have Been Used in Establishing Buffers

                         The preceding information has documented the ways that vegetated

                    buffer areas can provide protection for sensitive water resources. This

                    section will outline three distinct methods of establishing vegetated

                    buffer areas, will present examples of these three strategies as imple-

                    mented in various parts of the country, and will present recommendations

                    for the implementation of buffer areas in the coastal zone of the State of

                    Maryland.

                         The simplest method of establishing a buffer area is to define the

                    area as extending from the banks or high water mark of a watezcourse or

                    water body to some point landward. This approach has the advantage of

                    being easy to delineate and administer. Natural vegetation is preserved in

                    this area and any type of development or other land alteration is

                    prohibited within LLi..'.s area.

                         Fixed point boundaries from as little as 25 feet to as much as 300

                    feet have been established throughout the country with the buffer width

                    depending as much on political acceptability as scientific justifica-
                    tion.40

                         In Maryland, Cecil County has established a special waterfront

                    district consisting of all land within any commercial or industrial zone

                    adjoining tidal waters or wetlands and any land zoned otherwise within 110

                    feet of the mean high water line or tidal wetland. No buildings, struc-

                    tures and parking areas are allowed within the zone except (1) boat houses,

                    piers, docks, launching ramps, and mooring facilities; (2) marinas and

                    accessory uses in commercial zones; (3) beaches, bath houses and related

                    structures; and (4) industrial uses in areas appropriately zoned provided

                                                       20

              no industrial structures be located within 500 feet of the mean high
              waterline unless such structures are required for the operation of the
              industrial establishment. For such permitted uses, no on-site disposal of

              sewage or other waste is allowed within one hundred (100) feet of the mean
              high waterline. Restaurants, motels, and retail establishments serving the

              boating public are allowed no special exceptions. Within the district land

              surfaces and vegetation are to be preserved with vegetative removal or land

              alteration required to be in accordance with approved erosion and sediment

              control procedures or as part of crop tillage which is in accordance with

              an approved soil conservation plan.

                    In addition, Harford County has established a Natural Resources

              Protection District consisting of:

                    (1) areas exceeding 40,000 sq. ft. with a slope in excess of 25%;

                    (2) tidal and non-tidal wetlands greater than 40,000 sq. ft;

                    (3) buffer areas around third order streams consisting of 150 feet on

              both sides of the center line of the stream or 50 feet beyond the flood-

              plain, whichever is greater, and along their tributaries for a minimum

              distance of 300 feet from the main branch with a minimum distance of 50

              feet on both sides of the center line of the tributary or 25 feet beyond

              the floodplain, whichever is greater; and

                    (4) a buffer area of 500 feet from the waters edge of the Chesapeake

              Bay, Back River, Susquehanna River and the Gunpowder River.

                    Within this district, activities are restricted to protect water

              quality, minimize erosion/siltation and protect essential vegetation,

              protect shorelines, wetlands and beaches, protect steep terrain, protect

              person and property from environmental hazards, and, in general, ensure

              that use of land within the District protects the ecology of the area. In

                                                  21

                   particular, a 75 foot buffer is to be maintained adjacent to tidal and

                   non-tidal wetlands. Also, clearing of wooded areas is not to exceed 30% of

                   the wooded area with a minimum buffer area maintained adjacent to streams

                   of three times the height of canopy or 50 feet plus four feet for each 1%

                   increase in slope, whichever is greater.

                        Sensitive environmental areas, including special natural features,

                   significant wildlife habitats, cultivated soils, erosive soils and

                   designated scenic areas are not to be disturbed during any development. In

                   agricultural areas, a vegetative buffer of 25 feet is to be maintained

                   adjacent to stream banks to reduce run-off of sediment, fertilizer and

                   manure. Finally, shoreline areas adjacent to tidal waters are to be

                   minimally disturbed with a maximum of 30% impervious surfaces for a

                   distance of 100 feet landward from the water's edge with at least 50% of

                   any shoreline area maintained in permanent open space.

                        The main v-eakness of this method of establishing a buffer area is that

                   it does not make any provistcn for incorporating adjacent sensitive areas,

                   such as hillsides, poorly drained soils, or areas with high water tables

                   into the buffer area. It also does not take into account any special

                   problems which are t be used in developments adjacent to tidal waters.

                   For example, an increased buffer width may be needed to avoid nitrate

                   contamination.

                        A second method of establishing a buffer area would be to define the

                   area according to the character of adjacent lands. These lands would be

                   examined and such features as slope, vegetative cover, soil type and

                   porosity would be noted and taken into consideration in the development of

                   the required buffer area width. In areas where sensitive lands, such as

                   hillsides or poorly drained soils are in proximity to the water resource,

                                                        22

               the buffer area would be extended to include the sensitivity to critical

               areas along the stream. It is generally referred to as a floating buffer

               area.

                     Placer County, California defines its buffer areas (stream environment

               zones) in  this way:

                          A land strip on each side of the stream bed
                          necessary to maintain existing water quality.
                          The width of the stream environment zone shall
                          be determined by investigation. Investigation
                          shall consist of:

                          1. soil types and how surface water filters into
                             the ground;

                          2. types and amount of vegetative cover and how it
                             stabilizes the soil;

                          3. slope of the land within the zone and how signifi-
                             cant it is for retaining sediment from reaching the
                             streams.41

                     Fairfax County, Virginia has established environmental quality

               corridors to  protect its stream and adjacent lands which consist of:

                     1. all lands presently mapped as 100 year floodplains or subsequently
               mapped as such;

                     2. all floodplain soils and soils adjacent to streams which exhibit a
               high water table, poor bearing strength, or other severe development
               constraints;

                     3. tidal wetlan.s;

                     4. fresh water wetlands adjacent to streams;

                     5-steep slopes (greater than 15 percent) adjacent to the above
               floodplains, soils and wetlands; and

                     6. at a minimum, where the above floodplain, soils and wetlands cover
               only a narrow area, a buffer on each side of the stream calculated as
               follows: buffer width = 50 + (4 x percent slope) in feet.

                     The potential weakness of this approach lies in the evaluation of the

               buffer area. If the evaluation is inadequate, the buffer area provided may

               also be inadequate. An additional drawback of this approach is that it may

                                                        23

                    initially require large amounts of staff time to study the areas adjacent

                    to watercourses and water bodies to determine the requirements for buffer

                    areas.

                         A third approach, consisting of a combination of the above two

                    approaches, may well prove to be best. Under such a combination, a minimum

                    boundary would be specified, then adjusted depending on the location of

                    adjacent resource areas. If a proposed development abuts the fixed

                    boundary, the regulations defining the buffer area would require the

                    submission of environmental information regarding any resources within the

                    parcel. If areas of environmental significance or areas unsuitable for

                    development are present in the adjacent parcel, the boundary of the buffer

                    area would be extended to include these resources. If no such areas are

                    present in the adjacent parcel, the boundary would remain fixed.

                         The California Coastal Commission has utilized this approach in

                    establishing its Statewide Interpretive Guidelines for Wetlands and Other

                    Wet Environmentally Seitsltive Habitat Areas for its own use and that of

                    local coastal commissions. It requires a minimum buffer width of 100 feet

                    with additional area included in the buffer area upon the following

                    criteria: biologica significance of adjacent lands, sensitivity of

                    wildlife species occurring in the buffer area, susceptability of the area

                    to erosion, use of natural topographical features to locate development,

                    use of existing cultural features to locate buffer zones, lot

                    configurations, location of existing development, and type and scale of

                    development proposed.

                         In a variation of this approach, the New Jersey Department of

                    Environmental Protection has a New Jersey Coastal Resource and Development

                    Wetlands Buffer Policy (NJ Annotated Code, Section 7:lE-3.27) which states

                    that:

                                                         24

                        "All land within 300 feet of Wetlands as defined
                        in NJ AC 7:7E-3.26 and within the drainage of those
                        Wetlands comprise an area within which the need for
                        a Wetlands Buffer shall be determined."

                   The precise geographic extent of the actual Wetlands Buffer required

               is determined on a case-by-case basis to ensure any proposed development

               .1 will not have a significant adverse impact and will cause minimum feasible

               adverse impact, through the use of mitigation, where appropriate, (1) on

               the Wetlands, and (2) on the natural ecotone between the Wetlands and the

               surrounding upland."

               Recommendations for Establishing Buffer Areas

                    Based upon the results of the scientific studies noted above and the

               experience with the use of buffers in Maryland and elsewhere, it is

               recommended that a minimum buffer width of 100 feet be maintained from the

               mean high-water line of waterbodies or the edge of tidal and non-tidal

               wetlands. In addition, buffer areas should be sufficiently wide to include

               the 100-year riveripp floodplain, tidal wetlands, non-tidal wetlands, steep

               slopes (greater than 15%) adjacent to streams or the 100-year floodplain;

               soils with severe development. constraints (erodible soils, soils with a

               high water table, soils with poor bearing strength, etc.) adjacent to

               waterbodies or wetLids; and upland areas adjacent to waterbodies and

               wetlands which are of high biological significance. In the case of areas

               which have a slope of greater than 5 % adjacent to wetlands or waterbodies,

               the buffer area should contain an area of at least 25 feet from the top of

               the slope. Septic systems should be required to be a minimum of 150 feet

               from waterbodies. In the case of adjacent land areas of high nutrient

               loadings, a buffer width of 300 feet should be required in order to ensure

               the preservation of water quality.

                                                   25

                        la the case of agricultural uses, no-till farmi.ng j1ppears to greatly

                   reduce the sediment and nutrient rtmoff from agricultural lands and thus

                   buffer areas of lesser width may be appropriate. Also, the implementation

                   of effective soil conservation plans may reduce the width of the buffer

                   areas needed to protect water quality and aquatic resources.

                        Finally, buffer strips should be considered as valuable components of

                   a sediment control and stormwater management approach, but, in most cases,

                   they are not sufficient to minimize adverse effects from runoff by them-

                   selves. Their use, however, can reduce the cost and extent of sediment

                   control and stormwater management measures that otherwise would be required

                   and can retain sediment, nutrients, and non-point pollutants not caught by

                   other measures from entering water bodies and other environmentally

                   sensitive areas.

                                                        26

                                                 FOOTNOTES

                1 Water and Environmental Plannin  -g, Thomas Dunn and Luna Lepold, W.H.
                Freeman and Company, San Francisco, 1978.

                2 Ibid

                3 "Impact of Nearstr eam Vegetation and Stream Morphology on Water Quality
                and Stream Biota," James Karr and Issac Schlosser, U.S. Environmental
                Protection Agency, Athens, Georgia, August, 1977, EPA Document Number
                600/3-77-097.

                4 "Environmental Impact of Land Use on Water Quality," James Lake and
                James Morrison, U.S. Environmental Protection Agency, Chicago, Illinois,
                October, 1977, EPA Document Number 905/9-77-007.

                5 "Impact of Nearstream Vegetation and Stream Morphology on Water Quality
                and Stream Biota," OP. Cit.

                6 Ibid

                7 Ibid

                8 Carter, III, W. A. and John Foster III, Maryland Fisheries Administra-
                tion, Memo to Earl Shaver, Maryland Water Resources Administration on
                Fisheries Recommendations to a Waterway Construction Application by Howard
                S. Culver on Newastico Creek, Wicomico County, Maryland.

                9 "Impact of Nearstream Vegetation and Stream Morphology on Water Quality
                and Stream Biota," -P. 2i@L-

                10 "Environmental Impact of Land Use on Water Quality" op. Cit.

                11 Design of Vegetative Buffer Strips for Runoff and Sediment Control,
                Stanley L. Wong and Richard H. McCuen, Research Paper, Department of Civil
                Engineering, Univers4ty of Maryland, College Park, Maryland, 1981.

                12 "Impact of Nearstream Vegetation and Stream Morphology on Water Quality
                and Stream Biota" Op. Cit.

                13 Ibid

                14 "How Far from a Stream Should a Logging Road be Located," George R.
                Trimble, Jr. and Richard S. Schwartz, Journal of Forestry, Volume 55, 1957.

                15 "Maryland Uplands NaLaral Areas Study," John Rodgers, Stephan Syz,
                Fritts Golden, A report by Rodgers and Golden, Inc., Philadelphia,
                Pennsylvania, for Maryland Department of Natural Resources, 1976.

                16 "Impact of Nearstream Vegetation and Stream Morphology on Water Quality
                and Stream Biota," OP. Cit.

                                                       27

                     17 Ibid

                     18 "The Varying Source Area for Streamflow from Upland Basins," J.D.
                     Hewlett and W.L. Nutter, Procedural Symposium on the Interdisci linary
                     Aspects of Watershed Management, American Society of Civil Engineers, New
                     York, 1970.

                     19 The Effectiveness of Vegetative Buffer Strips for Runoff and Sediment
                     Control, op. Cit.

                     20 Ibid

                     21 "Impact of Nearstream Vegetation and Stream Morphology on Water Quality
                     and Stream Biota," Op. Cit.

                     22 Ibid

                     23 Ibid

                     24 Ibid

                     25 Ibid

                     26 Personal Communication with Dr. David Corell, Smithsonian Institution
                     Center for Environmental Studies, January 6, 1981.

                     27 Coastal Ecos_ystem Management, John Clark, The Conservation Foundation,
                     Job Wiley and Sons, New York, 1977.

                     28 "Impact of Nearst --,.m Vegetation and Stream Morphology on Water Quality
                     and Stream Biota" up. C:Lt.

                     29 Ibid

                     30 Ibid

                     31 Sommers, L.W., D.1- Nelson, and D.B. Kaminsky, "Nutrient Contributions
                     to the Maumee River, Non-Point Pollution Seminar, EPA-905/9-75-006. U.S.
                     Environmental Protection Agency, Chicago, Illinois, 1975.

                     32 "Water Resources and the Land-Water Interface  ,  James Karr and Issac
                     Schlosser, Science, Volume 201, July, 1978.

                     33 "Land Use and Trout Streams," G.F. Green, Journal of Soil and Water
                     Conservation, Volume 5, 1950.

                     34 "Effect of Woodland C.Learance on Stream Temperature," J.R. Gary and J.M.
                     Eddington, Journal of Fishery Resources Board of Canada, 1969.

                     35 "Forest Cuttings Raise Temperatures of Small Streams in the
                     Appalachians," L.W. Swift and J.E. Messer, Journal of Soil and Water
                     Conservation, 1971.

                     36 Ibid

                                                            28

               37 "Controlling Thermal Pollution in Small Streams" G.W. Brown and J.R.
               Brazier, US EPA Report No. R2-72-083, 1972.

               38 "Impact of Nearstream Vegetation and Stream Morphology on Water Quality
               and Stream Biota" Op. Cit.

               39 "National Wetlands Newsletter," Vol. 2 No. 4, July-Aug. 1980, Environ-
               mental Law Institute, Washington, D.C.

               40 Performance Controls for Sensitive Lands: A Practical Guide for Local
               Administrators, Charles Thurow, William Toner, and Duncan Erley, Washington
               Environmental Research Center, U.S. Environmental Protection Agency,
               Washington, D.C., March, 1975, EPA Document Number 600/5-75-00.

               41 Ibid

                                                      29

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                                                                         i
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