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Vegetated Riparian BuffersAnd Buffer Ordinances

2 Vegetated Riparian Buffers and Buffer Ordinances

Table Of Contents

Recommendations for Vegetated Buffers and BufferOrdinances in South Carolina .....................................................................................3I. Facts About Buffers ...............................................................................................4

A. The Advantages of Buffers ...............................................................................41. Water Quality and Aquatic Habitat Improvement ........................................42. Prevent Flooding, Drought, and Erosion ....................................................53. Wildlife Habitat Protection ..........................................................................54. Financial Benefits .......................................................................................55. Recreational Opportunities and Improved Aesthetics .................................6

B. Conditions Affecting Buffer Performance .........................................................61. Slope ............................................................................................................62. Vegetation ....................................................................................................63. Soil Type ......................................................................................................74. Buffer Width .................................................................................................75. Buffer Design ...............................................................................................86. Buffer Management ...................................................................................10

II. Problems and Solutions for Buffers and BufferOrdinances .......................................................................................................... 10A. Protecting the Rights of the Property Owner: Make the Buffer Ordinance

Flexible ...........................................................................................................101. Buffer Averaging ....................................................................................... 112. Density Compensation ............................................................................. 113. Conservation Easements ......................................................................... 114. Purchase of Development Rights ............................................................. 115. Variances .................................................................................................. 116. Allow Selective Pruning and Clearing to Provide a View Corridor ............12

B. Print Buffer Boundaries on Development Plans.............................................12C. Actively Manage Buffers ................................................................................13D. Minimize Crossings and Disruptions to the Stream Network .........................13E. Do not Rely Upon the Buffer as the Sole Stormwater Management Tool ......14

III. Examples of Existing Buffer Ordinances .............................................................15

Vegetated Riparian Buffers and Buffer Ordinances 3

Vegetated Riparian Buffers and Buffer Ordinances

Recommendations for Vegetated Buffers and Buffer Ordinances in SouthCarolina

I. Minimum average width 50 feet. The inner (streamside) zone of 25 feet (approximately two mature treesdeep) needs to be left pristine and forested. A width of 50 feet plus 25 feet of turf (residential backyard)before reaching the first pavement or structure is preferable, while a width of 100 feet (75 feet plus 25 feetof turf) is optimum and should be attempted where possible.A. Attempt to make two-thirds of the vegetated buffer at least 75 feet wide. Consider incentives to

developers (e.g. density bonuses elsewhere or property tax exemptions) for providing buffers of 75 or100 feet. See Figure 1 for the recommended three-zone riparian buffer design.

B. Do not allow the buffer to become too fragmented. Continuity is as important as buffer width. Do notallow more than 10% of the buffer to be less than 33 feet (10 meters) wide.

II. Establish specific water quality and habitat goals for the outer, middle, and streamside zones of the buffer.Adopt a vegetative target for the buffer based on the native, predevelopment plant community. Allowproperty owners to prune some vegetation in a portion of the buffer on their property so that they mayestablish a view of the water from their home.

III. Make the buffer ordinance flexible. The use of buffer averaging, density compensation, conservationeasements, and/or variances can ensure the rights of the property owner are protected.

IV. Actively manage buffers with annual buffer walks to ensure no improper encroachment by residents.Inform developers, builders, and residents on the location of and reason for the buffers. Make theboundaries of buffers visible before, during, and after construction with posted signs that describeallowable uses.

V. Print buffer boundaries on all development and construction plans, plats, and official maps.

VI. Limit the number and conditions for stream buffer crossings (e.g. roads, bridges, and underground utilities).All footbpaths running through the buffer to the water (perpendicular to the buffer) should be covered bynonelevated wooden boardwalks to prevent the channelization of stormwater runoff caused by dirtfootpaths.

VII. Do not rely on vegetated buffers as the sole stormwater management tool.

The purpose of this pamphlet is to provide basicinformation on riparian buffers. It is also intended asa general resource for local policy makers who areconsidering the creation of buffers or greenways intheir communities. It includes an annotated referencelist for those interested in pursuing the topic in moredetail.

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RIPARIAN AREAS. The term “riparian”refers to the area of land along a stream,river, marsh, or shoreline.


Nonpoint source (NPS) pollution fromstormwater runoff is a growing problem in SouthCarolina’s coastal areas. The water quality ofrivers and streams frequently becomes impaired inurbanized watersheds or where riparian corridors arealtered by such human activities as development oragriculture (WPT June 1997, pp. 490-491). Themovement of rainfall over urban and agricultural land-scapes flushes pollutants such as oil, gasoline,sediment, metals, and fertilizer into rivers, creeks, andestuaries. These pollutants:

• degrade water quality;• alter natural habitats for fish and other wildlife;• lead to excessive algae growth, which depletes

the oxygen needed by fish;• allow chemicals to accumulate in fish and

shellfish, which ultimately affectsconsumers.

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PURPOSES OF A RIPARIAN BUFFER:

• reduce erosion and stabilize streambanks.

• encourage infiltration of stormwaterrunoff

• control sedimentation.• reduce the effects of flood and drought.• provide forest areas to shade streams

and encourage desirable aquaticspecies.

• provide and protect wildlife habitat• offer scenic value and recreational

opportunity.• restore and maintain the chemical,

physical, and biological integrity of waterresources.

• minimize public investment in waterwayrestoration, stormwater management,and other public water resourceendeavors.

Schueler, WPT Summer 1995

I. Facts About RiparianBuffers

Riparian buffers or buffer zones are corridors ofvegetation along rivers, streams, and tidal wetlandswhich help to protect water quality by providing atransition between upland development and adjoin-ing surface waters. Vegetated riparian buffers filterurban stormwater runoff from impervious areasbefore it reaches the waterbody (U.S. EPA, 1993,pp. 4-47). Buffers also provide important wildlifehabitat, reduce flood and drought conditions, andcreate recreational opportunities.

THE ADVANTAGES OF BUFFERS

þ Water Quality and Aquatic HabitatImprovement

Many chemicals easily adsorb, or attach, toindividual sediment particles, so the sedimentparticles frequently carry pollutants and nutrients,such as nitrogen and phosphorus, into streams. Anoverabundance of nutrients in a waterbody causesalgae blooms; as the excess algae dies and decom-poses, oxygen is consumed, which kills plants, fish,and other aquatic life (Horton and Eichbaum, 1991).In addition, the sediment itself can be a pollutant, sinceit can impair the feeding and reproduction of manyforms of aquatic life (Anderson and Masters, 1993)Buffers act as a filter by reducing the amount of sedi-ment reaching the water. By slowing the movementof stormwater runoff, buffer vegetation allows moretime for sediment contained in the stormwater to settleout (Castelle et al., 1994).

When rainwater collects on roofed and pavedareas, it is heated by sunlight. This heated runoffraises the temperature of the receiving waterbody,which can limit fish spawning and also cause exces-sive algal growth. The tree canopy of a riparian buffershades the land below it and the receiving waterbody


to limit heating. One researcher found that shadingof small streams was adequate with a 50-foot wideforested buffer (Baltimore Buffer SubcommitteeRecommendations).

þ Prevent Flooding, Drought, andErosion

Vegetated buffers reduce downstream flooding byslowing stormwater velocity, storing some water insoils, and allowing more water to percolate to thewater table. Riparian buffers are useful also for floodzone management, keeping development back fromthe immediate banks of waterways and out of mostfloodways.

Riparian buffers reduce channelized flowerosion from stormwater runoff and stabilizestreambanks. The slow release of stored groundwa-ter from saturated soils in riparian areas helpsmaintain streamflow between storms and reducedrought conditions (Anderson and Masters, 1993).Leaves and grass on the ground act like a sponge byabsorbing water and then releasing it over time. Suchorganic debris also covers the soil, preventing splasherosion, and maintains infiltration capacity.

þ Wildlife Habitat Protection

Streams and the surrounding riparian areasprovide habitat for a diverse group of wildlife. These

animals either live in the riparian area or use the bufferas a travel corridor. For example, colonial waterbirdsneed buffers along the marsh-upland shoreline toprotect roosting and foraging sites (Dodd, 1998).Wildlife diversity within a buffer is linked to a buffer’ssize; i.e., wider buffers support a greater variety andnumber of species. A continuous buffer is ofparticular value in protecting amphibians, waterfowl,and coastal fish spawning and nursery areas (WPTJune 1997, pp. 471-472).

þ Financial Benefits

1. Minimizing Property DamagesBuffers mitigate property destruction by

maintaining some undeveloped land alongwaterways and keeping developing areas awayfrom floodwaters, storm surges, and extreme hightides (VBCZ, p. 29).

2. Decreased Public Investment NeedsBy reducing flooding, erosion, and sedimen-

tation, vegetated buffers minimize publicinvestment in stormwater management andwaterway protection and restoration (BaltimoreBuffer Subcommittee). Buffers can also reducethe number of drainage complaints received bylocal publicworks departments.

3. Increased Property ValuesIn a national study of ten programs that

diverted development away from flood-proneareas, researchers discovered that land next toprotected floodplains had increased in value byan average of $10,427 per acre (Burby, 1988). Inanother national study, buffers were thought tohave a positive or neutral impact on adjacentproperty values in 32 out of 39 communitiessurveyed (Schueler, 1995). Homes located nearseven California stream restoration projects hada 3 to 13% higher property value than similarhomes located on unrestored streams (Streiner andLoomis, 1996).


“When managed as a ‘greenway,’ streambuffers can expand recreational opportunities andincrease the value of adjacent parcels (Flink andSearns, 1993). Several studies have shown thatgreenway parks increase the value of homes ad-jacent to them...” (WPT, June 1997 pp. 471-472).

4. Reduced Maintenance Costs“Corporate landowners can save between

$270 to $640 per acre in annual mowing andmaintenance costs when open lands are managedas a natural buffer area rather than turf,” (Wild-life Habitat Enhancement Council, 1992 - as citedin WPT June 1997, pp. 471-472).

þ Recreational Opportunities andImproved Aesthetics

Many urban areas are combining the habitat andwater quality benefits of buffers with therecreational and transportation advantages ofgreenways. Trail systems provide an alternate meansfor people to travel and can be a principle place forrecreation. Greenways serve to make communitiesmore attractive places to live and tend to boost localeconomies. Quality of life can be an important factorin many corporate relocation decisions.

CONDITIONS AFFECTING BUFFERPERFORMANCE

The effectiveness of a buffer in achieving waterquality benefits depends on several conditions,including:

• buffer slope• vegetation• soil type• buffer width• buffer design• buffer management

þ Buffer Slope

Several researchers have concluded that the slopeof a buffer should not exceed fifteen percent (Schueleret al., 1992). Above fifteen percent, the velocity ofrunoff becomes too fast, and sediment particles willnot have time to settle out. Runoff is likely tobecome concentrated and channelized, rendering thebuffer much less effective (Baltimore Buffer Subcom-mittee). Shallower slopes allow for longer residencetime, slower flow, and are more effective atremoving sediment and pollutants from the runoff.

“Use near construction sites and agricultural fieldsthat yield heavy sediment loads requires a buffer slopegreater than 1% or the sediment deposits may need tobe removed or spread after each heavy rainfall. Atemporary silt fence could also be installed and thedeposits removed at the end of construction or thefarming season. After construction and where sedi-ment loads from existing urban developments aremoderate, buffer slopes may be as low as 0.5% andstill only require normal annual maintenance... [L]andslopes average 0.2% in the Cooper, Wando, andAshley river basins, and near the wetland margins tendto steepen to 0.5% to 1%, (McCutcheon et al., 1999).If sediment buildup is not expected, the shallowerslopes (


If runoff is allowed to “short circuit” a buffer byconcentrating and forming channels or rivulets, thechance for filtration of runoff is greatly reduced. Themore dense the vegetation is in a buffer, the better itwill filter runoff.

If the intended use of a buffer is solely forstormwater filtration, grasses work best, because treesand shrubs allow more channelization of runoff(McCutcheon et al., 1999). However, grasses do notprovide the habitat of forested buffers. In addition,removing trees and shrubs along a streambank tocreate a grassed buffer can erode the streambank.Grassed buffers also require mowing two or threetimes annually to prevent the natural succession ofbushes and trees (McCutcheon et al., 1999), and theyprovide no shade for the land or the waterbodies.

þ Soil Type

Medium-fine textured soils, such as loams andsilt loams, work best to establish plants, filter pollut-ants, retain surface water, and increase groundwaterdischarge to streams. Highly permeable soils, suchas coarse-textured sandy soils, may percolate waterso rapidly that little uptake of excess nitrogen occurs.Well-drained soils are only half as effective at remov-ing nitrogen as poorly drained soils. The saturated,organically rich soils typically found in salt marshes,wetlands, and wet forests are useful in the removal ofboth soluble and sediment-bound pollutants. Sandy

Table 1. Example buffer width formulas.

• 50 ft. + 4-5 ft. for every 1% increase in slope(Trimble and Schwartz, 1957; Aucella, 1989).

• 75 ft. for slopes less than 10%. Additional widthmay be added for steeper slopes (Carter, 1988).

• 3 times the maximum height of the tree canopy(Palfrey and Bradley, 1982).

soils may be most effective in removing sedimentsand sediment-bound pollutants, but only marginallyeffective at removing soluble forms of pollutants.

þ Buffer Width

The ability of a buffer to provide multiplebenefits is closely linked to width. A national surveyof 36 local buffer programs found a range in widthfrom 20 to 200 feet on each side of the stream, with amedian of 100 feet. The buffer programs surveyedgenerally incorporated the 100-year floodplain andsome included adjacent wetlands, steep slopes orcritical habitat areas. In most regions of the country,100 feet translates to three to five mature trees deepon each side of the stream (WPT Summer 1995,p. 157). The only types of development allowed inthese areas are usually limited to those structuresneeded to allow reasonable use of the property, suchas docks (U.S. EPA, 1993, pp. 4-47).

Table 1 lists several methods suggested fordetermining appropriate buffer widths. The methodslisted have been used by many municipalities.

The Environmental Protection Agencyrecommends a 100-foot minimum buffer of nativevegetation landward from the mean high tide line incoastal areas to help remove or reduce sediment, ex-cess nutrients, and toxic substances entering surfacewaters (MWCOG, 1991). A main difference between


tidal creeks and freshwater streams is that research-ers recommend bigger buffers for bigger freshwaterstreams, but the opposite is true for tidal creeks. Sincesmall tidal creeks are critically important spawningand nursery areas, bigger buffers are recommendedfor small tidal creeks. Tributaries of non-tidallyinfluenced freshwater streams have not been shownto be as important to freshwater stream ecosystems.

In a University of Washington study, “twenty-twosmall-stream watersheds [were] chosen to representa range of development levels from relativelyundeveloped (reference) to highly urbanized. In thisstudy, the streambank stability [was found to bedirectly related] to the width of the riparian bufferand inversely related to the number of breaks in theriparian corridor,” (WPT June 1997, pp. 488-489).This study found that “wide, continuous, and mature-forested riparian corridors appear to be effective inmitigating at least some of the cumulative effects ofadjacent basin development.” Results of the studysuggest that“enhancement and mitigation effortsshould be focused on watersheds where ecologicalfunction is impaired but not entirely lost...” (WPT June1997, pp. 490- 491). The study made severalrecommendations to maintain existing natural streamquality:

1. Ensure that at least 70% of the riparian corridorhas a minimum buffer width of 30 m [approx.100 ft.] and utilize wider (100m) buffers aroundmore sensitive or valuable resource areas [Abuffer width of less than ten meters (approxi-mately thirty-three feet) is generally consideredfunctionally ineffective (Castelle et al., 1994)].

2. Limit encroachment of the riparian buffer zonethrough education and enforcement (


Stream

Foot path

Bike pathPosting

Fence

Compostpile

INNER CORE MIDDLE CORE OUTER CORE

Figure 1: Schematic of a three-stage stream buffer.

Buffer Width Pollutant Removal Effectiveness Wildlife Habitat Value

5 meters Approximately 50% or greater Poor habitat value; useful for temporarty(approx 16.5 ft.) sediment and pollutant removal. activities of wildlife.10 meters Approximately 60% or greater Minimally protects stream habitat; poor(approx 33 ft.) sediment and pollutant removal. habitat value; useful for temporary activities of wildlife.15 meters Greater than 60% sediment and Miinimal general wildlife and avian(approx 50 ft.) pollutant removal. habitat value.20 meters Approximately 70% or greater Minimal wildlife habitat value; some(approx 66 ft.) sediment and pollutant removal. value as avian habitat.30 meters Approximately 70% or greater May have use as a wildlife travel(approx 100 ft.) sediment and pollutant removal. corridor as well as general avian habitat.50 meters Approximately 75% or greater Minimal general wildlife habitat value(approx 165 ft.) sediment and pollutant removal.75 meters Approximately 80% or greater Fair-to-good general wildlife and avian(approx 248 ft.) sediment and pollutant removal. habitat value100 meters Apporximately 80% or greater Good general wildlife value; may(approx 330 ft.) sediment and pollutant removal. protect significant wildlife habitat.200 meters Approximately 90% or greater Excellent wildlife value; likely(approx 660 ft.) sediment and pollutant removal. to support a diverse community.

Table 2: A summary of pollutant removal effectiveness and wildlife habitat value of vegetated buffersaccording to buffer width (1 meter=3.28 feet) (Source: Desbonnet et al. 1994).

WATER SOURCEwater quality &aquatic habitatenhanced.

STREAMSIDE ZONE25 ft. wide;mature forest;very restricted uses.

MIDDLE ZONE50+ ft. wide;managed forest;restricted uses.

OUTER ZONE25+ ft. wide;forest or turf;few restrictions.

Source: Schueler, WPT 2/94, p.19 (Graphic Courtesy of the Center for Watershed Protection)


The outer buffer zone: 25 feet wide minimum,composed of forest or turf. It is the buffer’s buffer, anadditional 25-foot setback from the outward edge ofthe middle zone to the nearest permanent structure. Itis usually a residential backyard. The only major re-strictions are no septic systems, no new impervioussurfaces, and no new permanent structures (WPTSummer 1995, p. 157).

þ Buffer System Management

Buffer management is covered in depth in the followingsection.

II. Problems andSolutions for Buffersand Buffer Ordinances

PROTECTING THE RIGHTS OF THEPROPERTY OWNER: MAKE THE BUFFERORDINANCE FLEXIBLE

Since in most watersheds a 100-foot bufferordinance will take about 5% of the total land areaout of development consideration, many communi-ties are concerned that stream buffer requirementscould represent an uncompensated taking of privateproperty. This situation can be mitigated by making abuffer ordinance more flexible (WPT Summer 1995,p. 162).

To address the concern that stream buffer require-ments could represent an uncompensated taking ofprivate property, a community can incorporateseveral simple measures to ensure fairness andflexibility when administering its buffer program(WPT Summer 1995, p. 162).

“Buffer ordinances that retain property in privateownership generally are considered by the courts toavoid the takings issue, as buffers provide compel-ling public safety, welfare, and the environmentalbenefits to the community that justify partialrestrictions on land use. Most buffer programs meetthe ‘rough proportionality’ test recently advanced bythe Supreme Court for local land use regulation(Hornbach, 1993) ... [S]tream buffers are generallyperceived to have a neutral or positive impact onadjacent property value. The key point is that thereservation of the buffer cannot take away alleconomically beneficial use for the property.” Sixtechniques described below can ensure that theinterests of the property owners are protected (WPTSummer 1995, p. 162).


1. Buffer Averaging

Buffer averaging permits the buffer to becomenarrower at some points along the stream, as long asthe average width of the buffer meets the minimumrequirement. However, buffer narrowing must be limited, so that the streamside zone is not disturbedand no new construction is allowed within the100-year floodplain. Since continuity in the buffer isas important as width, do not allow more than 10%of the buffer to be less than 33 feet (10m) wide (WPTSummer 1995, p. 162).

2. Density Compensation

“This scheme grants a developer a credit foradditional density elsewhere on the site, in compen-sation for developable land that has been lost due tothe buffer requirement... Credits are granted whenmore than 5% of developable land is consumed. Thedensity credit is accommodated at the developmentsite by allowing greater flexibility in setbacks, front-age distances or minimum lot sizes to squeeze in ‘lostlots.’ Cluster development also allows the developerto recover lots that are taken out of production due tobuffers and other requirements. The intent of streambuffers is to modify the location but not the intensityof development,” (WPT Summer 1995, pp. 162-163).

3. Conservation Easements

“[An] easement conditions the use of the buffer,and can be donated to a land trust as a charitable con-tribution that can reduce an owner’s income tax bur-den. Alternatively, the conservation easement can bedonated to a local government, in exchange for a re-duction or elimination of property tax on the parcel,”(WPT Summer 1995, pp. 162-163).

4. Purchase of Development Rights

“Purchase of development rights could be con-sidered by local governments if a proposed bufferwould encompass all or nearly all of a propertyowner’s developable land. It is “a tool that achievessome of the same goals as conservation easements,in that another landowner may purchase the rights todevelop a property from the owner. When the land issold or inherited, it retains the prohibition againstdevelopment,” (WPT June 1997, p. 479).

5. Variances

“The buffer ordinance should have provisions thatenable an existing property owner to be granted avariance or waiver, if the owner can demonstratesevere economic hardship or unique circumstancesmake it impossible to meet some or all of the buffer


requirements. The owner should also have access toa defined appeals process should the request… bedenied,” (WPT Summer 1995, p. 163).

6. Allow Selective Pruning and Clearingto Provide a View Corridor

Allow property owners to prune vegetation in aportion of the buffer on their property to afford thema view of the water a “view corridor.” Keep suchcorridors either 75 feet wide or one-third the width ofeach lot, whichever is less. A landowner should alsohave the option to submit a selective clearing and land-scaping plan for the view corridor. Such a plan mustleave or replace enough vegetation in the corridor tomaintain the value of the buffer. To prevent conver-sion of the area to turf, do not allow pruning below aheight of three feet.

PRINT BUFFER BOUNDARIES ON ALLDEVELOPMENT PLANS

Buffer boundaries are often invisible to propertyowners, developers, and even local governmentofficials. Without defined boundaries, urban buffersare subject to encroachment and incompatible uses.Landowners are more often unaware of buffers thandeliberately violating buffer boundaries.

Over 60 percent of the local governmentssurveyed in a national survey of 36 local bufferprograms (Heraty, 1993) indicated that mostindividual property owners were unaware of eitherthe boundary or the purpose of a buffer. One-timelegal disclosures, such as notes on the deed of salewere usually the only notification given to propertyowners about buffer limits. Local governments needto record the buffer boundaries on their own officialmaps. Such buffer maps are necessary so localgovernments can inspect and manage their networkof buffers and evaluate the potential impact of newdevelopment at specific sites in the buffer network(WPT 2/94, pp. 19-20).

In a study of 21 buffers in Seattle ranging fromtwo to eight years old, ninety-five percent had beenvisibly altered, including tree removal, conversion intolawns, and erosion by stormwater runoff. In onehundred percent of the residential lots located withinnarrow buffer networks, natural vegetation had beencleared and replaced by lawns. Encroachment intoriparian buffer zones is extremely difficult to control.(WPT 2/94, pp. 20-21). Boundaries for vegetatedbuffers printed on all development plans delineate thelimits of disturbance during construction, decreasingthe likelihood that contractors will encroach ordisturb the buffer (WPT February 1994, p. 19).

Dwelling

Lawn Lawn

Buffer areato remainundisturbed

Buffer areato remainundisturbed

ViewCorridor

4' widewalkover 50' buffer

100' lotwidth atedge of marsh

Edge of creekDock

Edge of marsh

Driveway

33'

Figure 2: Example of a Selective Clearing andLandscape Plan

• View corridor to be maintained by pruning brush to aheight of 3’

• View corridor at shore = 33’/100’ of buffer length atcoastal feature = 33%


ACTIVELY MANAGE BUFFERS

Due to staff constraints, in almost every jurisdic-tion surveyed in the Seattle study, only one inspec-tion of property within buffer zones is performed,usually at the end of construction. Subsequentpost-construction “bufferwalks” are rare or nonexist-ent (WPT 2/94, p. 20). However, after requiringbuffers during development review, localgovernments must also make the effort to managebuffers after they become established. Render themvisible to contractors, users, and property ownersbefore, during, and after construction. Install siltfencing outside the limit of the buffer to keep silt outof the buffer. Buffer education and enforcement arealso needed to protect buffer integrity (WPT 2/94,p. 21; WPT Summer 1995, p. 157).

Additional recommendations for buffermanagement:• “Verify the stream delineation in the field;• Mark buffer limits on all plans used during

construction (i.e., clearing and grading plans,and erosion and sediment control plans), plats,and other official maps;

• Conduct a preconstruction stakeout of buffersto define limits of disturbance;

• Mark the limits of disturbance with silt or snow

fence barriers, and signs to prevent the entry ofconstruction equipment and stockpiling;• Mark the buffer boundaries with permanent

signs that describe allowable uses;• Conduct annual bufferwalks to check on

encroachment;” (WPT Summer 1995,pp. 160-162)

• Inform buffer owners using pamphlets,interpretive buffer-walks, and meetings withhomeowners associations;

• Ensure new property owners are made awareof the buffer limits/uses when property is soldor transferred;

• “[S]ome kind of limited enforcementprogram may be necessary. This usuallyinvolves a series of correction notices and sitevisits, with civil fines used as a last resort...Some buffer ordinances have a furtherenforcement option, whereby the full cost ofbuffer restoration is charged as a propertylien,” (WPT Summer 1995, p. 162).

MINIMIZE BUFFER CROSSINGS ANDDISRUPTIONS TO THE STREAM NETWORK

“Fragmentation of the riparian corridor in urbanwatersheds can come from a variety of humanimpacts; the most common and potentially damagingbeing road crossings. [In a University of Washingtonstudy], the number of stream crossings (roads, trails,and utilities) increased in proportion todevelopment intensity... In general, the morefragmented and asymmetrical the buffer, the wider itneeds to be to perform the desired functions (Bartonet al., 1985),” (WPT June 1997, p. 486).

1. Develop performance criteria to specificallydescribe the conditions under which the streamor its buffers can be crossed with linear forms ofdevelopment, such as roads, bridges, and under-ground utilities.

• “Crossing width: Minimum width to allow formaintenance access.


• Crossing angle: Use direct right angles to crossstreams since they require less clearing in thebuffer than oblique crossing angles.

• Crossing frequency: Allow only one road cross-ing within each subdivision

• Crossing elevation: All roadway crossings andculverts should be capable of passing the ultimate100-year flood event, and, where feasible, lowerone culvert below stream invert to ensure waterduring low-flow periods...” (WPT Summer 1995,pp. 158-159).

2. Reduce road right-of-way in buffer zone, withutilities under pavement.

3. Avoid crossing stream with mainline sewer.4. Site sewers out of buffers (WPT Summer 1995,

p. 159).5. Use buffers to minimize the impact of golf courses

on streams:a. Construct all fairway crossings perpendicu-

lar to the stream.b. Allow no more than one golf fairway

crossing for every 1,000 feet of buffer.c. Protect all wetlands with an extra buffer.d. Treat outflow with a combination of

vegetative BMPs (filter, swale, wetland).(adapted from Powell and Jolley, 1992) WPTSummer 1994, p. 74; WPT Summer 1995,p. 158)

DO NOT RELY UPON THE BUFFER AS THESOLE STORMWATER MANAGEMENT TOOL

The capacity of vegetated buffers to removepollutants in urban stormwater is fairly limited. Inurban watersheds rainfall is rapidly converted intoconcentrated flow. If flow is allowed to concentrate,it forms a channel that effectively bypasses a buffer.As much as 90% of urban runoff concentrates beforeit reaches a buffer, ultimately crossing it in a channelor stormwater drain pipe. Therefore additionalstructural BMPs are usually needed to removepollutants from runoff before they reach a stream(WPT Summer 1995, p. 155).

Only use the stream buffer as a stormwaterfiltering system “if basic maintenance can be assured,such as routine mowing of the grass filter and annualremoval of accumulated sediments at the edge of theimpervious areas and the grass filter,” (WPTSummer 1995, p. 160).

Constructing stormwater ponds on or near thestream provides treatment of the greatest possibledrainage area, making construction easier and cheaper.In some areas, ponds and wetlands “require the dryweather flow of a stream to maintain water levels andprevent nuisance conditions. Lastly, ponds and


wetlands add a greater diversity of habitat types andstructure and can add to the total buffer width in somecases. On the other hand, placing a pond or wetlandin the buffer can create environmental problems,including the localized clearing of trees and streamwarming...” Therefore it is useful to consider possibleperformance criteria that restrict the use of ponds orwetlands:

1. A maximum contributing area (e.g. 100acres)

2. Clearing of the streamside buffer zone onlyfor the outflow channel (if the pond is dis-charging from the middle zone into thestream),

3. Use ponds only to manage stormwaterquantity within the buffer,” (WPT Summer1995, p. 160).

Buffer Design in Relation to Pavement:

“When the buffer receives flow directly from animpervious area, design curb cuts or spacers to spreadrunoff evenly over the buffer strip. Locate the buffer3 to 6 inches below the pavement surface to preventsediment deposits from blocking inflow to the buffer.A narrow stone layer at the pavement edge can servethis purpose,” (WPT Summer 1995, p 160).

III. Examples of ExistingBuffer Ordinances

Numerous states and communities have imple-mented requirements for various types and sizes ofbuffers. Some examples are given below (contact thestate or individual community for more detailed in-formation).

Brunswick, MaineThe city adopted 125-300 foot buffers from mean

high water within the Coastal Protection Zone. Theexact width is determined by the slope of the buffer,as designated on the town’s land use map (USEPA,1993, pp. 4-48).

Chesapeake BayThe states of Maryland and Virginia have buffer

programs in effect to protect the Chesapeake Bay.Both states require a 100-foot vegetated buffer alongthe shoreline of the Bay and its tributaries. In Mary-land, the buffer requirement is only applicable to newdevelopment; however, the requirement may bewaived if “good conservation practices” are utilizedat the shoreline. Virginia’s Chesapeake Bay Preser-vation Act does provide for limited use within thebuffer, generally allows for marinas and docks withinthe buffer, and can grant variances for utilizing landwithin the buffer area; however, no variance will re-sult in a vegetated buffer of less than 50 feet (exceptfor agricultural uses) (Desbonnet et al., 1994).

Alexandria, VirginiaThe city of requires buffers in all designated Re-

source Protection Areas (RPAs). Buffer must reduce75% of sediments and 40% of nutrients. Buffers of100 feet are considered adequate to achieve this stan-dard, and smaller widths may be allowed if they canbe proven to meet sediment and nutrient removal re-quirements. “Indigenous vegetation removal is lim-ited to that necessary to provide reasonable sight lines,access paths, general woodlot management, and BMPimplementation,” (USEPA, 1993, pp. 4-48).


Queen Annes County, MarylandThe county has a standard shoreline buffer of 300

feet from the edge of tidal waters or wetlands, with atleast 50 percent forested (USEPA, 1993, p. 4-48).

IllinoisThe state has adopted a five-sixths property tax

exemption for vegetated buffers managed in accor-dance with a plan approved by the county conserva-tion district. The protected zone must be at least 66feet wide and “contain vegetation that ‘has a densetop growth, forms a uniform ground cover, [and] hasa heavy fibrous root system,’” (NPSN 4/5 1998,p. 11).

MassachusettsThe state’s new Rivers Protection Act establishes

a 200-foot wide buffer zone along the state’s peren-nial rivers and streams (NPSN 4/5 1998, p. 11).

North CarolinaThe state has adopted a 50-foot protected, veg-

etated zone on each side of the Neuse river (NPSN 4/5 1998, p. 11). In North Carolina’s coastal zone man-agement program, the portion of the coastal zone thatlies within 75 feet of the water’s edge is subject topermit approval for development purposes.

Beaufort, South CarolinaTo protect water quality and habitat, “a buffer strip

of 50 feet from the OCRM critical line was estab-lished in 1995 on all waterfront property. The bufferstrip must be maintained as an undeveloped landscapeor undisturbed natural area with some restricted usesallowed in the area. The River Protection District alsoestablishes development setbacks of 50, 100, and 150feet from the OCRM critical line, depending on theintended development,” (NPSN 4/5 1998, p. 11).

Beaufort’s Buffer Regulations:

“[A] buffer strip of existing or planted vegeta-tion is established within the District, extending fiftyfeet perpendicular to and in a horizontal plane fromthe OCRM Critical Line. The purpose of this bufferstrip is to:

1. provide a natural filtration system for runofffrom adjoining development that may enterthe waters;

2. minimize erosion and help stabilize thestreambank;

3. provide a natural habitat for the flora andfauna that exist in this important transitionarea between wetland and upland areas... Theentire buffer must be maintained as anundeveloped landscaped area.”

“ No development is permitted in the buffer withthe exception of the following six uses:

1. Pedestrian and/or vehicular access waysleading to docks, fishing piers, boatlandings... provided that only permeable... orsemi-permeable materials ... are used forvehicular access ways…

2. [the structures that the vehicular access wayslead up to]

3. Use of grassed swales rather than drainagepipes is required...

4. Approved flood control and erosion controldevices...

5. Utility lines serving approved water/marshuses or crossing the water/marsh...

6. Installation of playground equipment orbenches, picnic tables or other similaroutdoor furniture.”

“Roads leading to bridges that cross the water-way [are allowed] provided the roads are placed ap-proximately perpendicular to the line of the bufferand provided all shoulders are grassed.”


“The following uses within the River ProtectionOverlay District shall be set back a minimum of fiftyfeet from the OCRM Critical Line: agricultural uses...regulation golf courses... recreational parks andplaygrounds...drainage systems and retention ponds.”

“The following require a one hundred-foot set-back: detached single family residential units, multi-family and attached residential units, parking areasand driveways, garages, [civic buildings] not largerthan four thousand square feet, parking lots with nomore than [6 spaces or 1000 square feet], ... and ROWof two-lane road.” Any uses not specified in the RiverProtection District must be set back a minimum ofone hundred fifty feet (Beaufort County River Pro-tection Overlay District Ordinance, pp. 3-6).

CONCLUSION

Vegetated riparian buffers along urbanwaterbodies have proven to be effective against pol-luted runoff, flooding, and erosion while protectingaquatic and terrestrial habitats. However, scientificresearch often encourages the use of buffers that arewider than what many communities are willing toaccept. After informing citizens on the need for buff-ers and receiving public input, community leadersmust decide on buffer widths that both afford a mea-sure of protection for riparian zones and are accept-able within the community (politically feasible). Usethe information presented in this document as a guidefor establishing appropriate buffers and for resolvingany conflicts that may arise from a proposed bufferordinance.


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