buffer area study

[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

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

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

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

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).

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

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.

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.

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

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

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

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

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.

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

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.

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.

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.

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

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

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

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,

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

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:

"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.

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.

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.

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

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

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i
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