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FY 1992 FINAL PRODUCT Task 9 Permit Compliance & Inspection Wetlands Guidelines him- VIRGINIA Ca co . I I . . . . . . . . 0 &, C -- C* Prepared by The Department of Wetlands Ecology Virginia Institute of Marine Science College of William and Mary and The Habitat Management Division Virginia Marine Resources Commission Developed Pursuant to Chapter 13 of Title 28.2, Code of Virginia Reprinted September 1993 "This reprint was funded, in part, by the Virginia Council on the Environment's Coastal Resources Management Program through Grant #NA270ZO312-01 of the Natio'nal Oceanic and Atmospheric Administration, Office of Ocean and Coastal Resource Management, under the Coastal Zone Management Act of 1972 as amended." Printed on recycled paper.@ Wetlands Guidelines Table of Contents Section I Introduction . . . . . . . . . . . . . . . . . . . . . . . 1 Section II Wetlands Types and Properties . . . . . . . . . . . . 3 Type I Saltmarsh Cordgrass Community . . . . . . . . 7 Type II Saltmeadow Community . . . . . . . . . . . . . 9 Type III Black Needlerush Community . . . . . . . . . . 11 Type IV Saltbush Community . . . . . . . . . . . . . . . 13 Type V Big Cordgrass Community . . . . . . . . . . . . 15 Type VI Cattail Community . . . . . . . . . . . . . . . . 17 Type VII Arrow Arum-Pickerel Weed Community . . . . . 19 Type VIII Reed Grass Community . . . . . . . . . . . . . . 21 Type IX Yellow Pond Lily Community . . . . . . . . . . . 23 Type X Saltwort Community . . . . . . . . . . . . . . . 25 Type XI Freshwater Mixed Community .......... 27 Type XII Brackish Water Mixed Community ........ 29 Type XIII Intertidal Beach Community ........... 31 Type XIV Sand Flat Community ............... 32 Type XV Sand/Mud Mixed Flat Community ........ 33 Type XVI Mud Flat Community ............... 34 Type XVII Intertidal Oyster Reef Community ........ 35 Section III Evaluation of Wetlands Types . . . . . . . . . . . . . 37 Section IV . Criteria for Evaluating Alterations of Wetlands . . . . 41 Section V Wetlands Mitigation-Compensation Policy ...... 63 Glossary ................................ 69 Wetlands Guidelines Wetlands Guidelines Section I Introduction Virginia's coastal zone is composed of many different but highly interrelated ecological systems. Below the low tide limits are found the vast areas of submerged bottomland which are vitally important as fish and shellfish feeding, spawning and nursery habitat. These areas not only help support Virginia's highly valu- able commercial catch but also the myriad of species which the average Virginian never directly encounters but nevertheless are as important ecologically as the commercially sought organ- isms. Between the high water line and the low water line are found the nonvegetated intertidal flats and beaches. These areas, though uncovered and seemingly devoid of life during a portion of each tidal.cycle, provide important habitat for a host of differ- ent marine organisms, aquatic birds and many mammals. Beginning approximately at the elevation we call mean sea level are found the various vegetated communities known as marshes. Best known for their high plant production on the or- der of tons per acre per year, marshes have other valuable func- tions. They are a buffer between the estuary and the upland; interacting with both. With the passage of House Bill 400, which adds nonvegetated in- tertidal areas to the existing wetlands protection mechanism, the General Assembly has not only recognized the value of inter- tidal flats and beaches to the Commonwealth but also the inter- related and interdependent nature of the vegetated and nonvegetated wetlands systems. All wetland resources of the Commonwealth will now be managed under a single, unified pro- gram. Moving landward from mean low water (the Marine Re- sources Commission controls the bottomland seaward of mean low water) wetland jurisdiction now extends to mean high water where no emergent vegetation exists, and to 1.5 times the mean tide range where marsh is present. All intertidal areas are now Wetlands Guidelines called wetlands and can be managed holistically under a single permit system. The purpose of this document is to revise the existing Wetlands Guidelines, which deal only with marshes, to include beaches, tidal flats and subaqueous lands as well. Although scientific re- search has yet to clearly define and quantify all aspects of wet- lands function and importance within the estuary, there are few in, the scientific community who would argue that these areas are not highly significant systems whose conservation is very im- portant to the Commonwealth. The policy stated by the legisla- ture when it passed the vegetated wetlands act in 1972 is as relevant today as it was then: "Therefore, in order to protect the public interest, promote the public health, safety and the economic and general welfare of the Commonwealth, and to protect public and private prop- erty, wildlife, marine fisheries and the natural enVironment, it is declared to be the public policy of this Commonwealth to preserve the wetlands, and to prevent their despoliation and destruction and to accommodate necessary economic develop- ment in a manner congistent with wetlands preservation." In the pages that follow, the value of the wetlands to the Com- monwealth and its citizens is described. This is followed by a brief description of each community type and then by an environ- mental value ranking system. In this section the community types are ranked relhtive to each other according to their envi- ronmental values. It should be noted that all wetlands are im- portant but where management decisions must be made rIegarding necessary economic development in wetlands, this ranking system may help in guiding development into the lesser value wetland communities. The ranking system is Olowed by the general and specific guide- lines for wetland disturbing activities. These guidelines have been expanded to cover the nonvegetated area and to deal with issues that have arisen since the adoption of the original guide- lines in 1974. it is intended that these guidelines aid wetland managers in preserving the wetlands while accommodating nec- essary economic development along Virginia's 5000 'miles of shoreline. 2 Wetlands Guidelines Section II Wetlands Types and Properties Wetlands, as defined in Chapter 13 of Title 28.2 of the Code of Virginia, fall into two major groupings: vegetated (tidal marshes and swamps) and nonvegetated (intertidal flats, bars and beaches). Although seldom recognized by the general public ex- cept as exhibited in the desire to live on or near the water, wet- lands have a variety of both tangible and intangible values which place them in a position of inestimable importance to the Commonwealth. This section of this document first identifies the primary values of the wetlands, then describes the general wetland types found in "Tidewater" Virginia, and finally ranks these types relative to each other in terms of these primary values. Each wetland type is evaluated in accordance with five general values. These are: A. Production and detritus availability. Marshes and tidal flats are major sites of primary production in the marine eco- system. When this plant material dies and begins to decay (detritus) it becomes the basis of a major marine food path- way. The productivity of all the major marsh community types is Well documented and ranges from one to six tons per acre per year. Generally, the lower the elevation of the marsh, the greater its contribution of detritus and the greater its value to the aquatic environment. Plant productivity on tidal flats is typically less than that of tidal marshes but higher than the bottom in deeper open water areas due to the greater supply of light and nutrients available. Plant productivity in intertidal areas is dominated by nonvascular plants (bottom-dwelling, one-celled micro- and macroalgae). Probably the most important function of the nonvegetated wetlands is that of mediating the break- 3 Wetlands Guidelines down of detritus produced on the vegetated marshes. Tidal flats located adjace 'nt to extensive marsh areas may there- fore be more biologically valuable than more isolated tidal flats. As mediators of detrital breakdown, nonvegetated wet- lands are 6ften the sites of large, diverse invertebrate popula- tions and are often major feeding sites and spawning and nursery grounds for estuarine organisms of sport and com- mercial value to man. B. Waterfowl and Wildlife Utilization. Long before wetlands were discovered to be detritus producers and feeding areas for marine organisms, they were known as rich habitats for various mammals, marine birds and migratory waterfowl. Some wetland types are more important than others in this. regard but in many cases distinctions may not be -clear-cut. A species, for example, may appear to be dependent on vege- tated marsh for cover and breeding but; without the adjacent tidal flats may not use a certain marsh at all. Wetlands offer- ing a variety of habitats and plant types are generally the more valuable from a habitat perspective. C. Erosion Buffer. Erosion is a common problem throughout coastal Virginia and is by no means limited to ocean beaches. Vegetated wetlands do erode but by virtue of their ability to establish dense root systems, trap and accumulate sedi- ments, and baffle wave energy they are buffers against ero sion and sea level rise. Among the vegetated wetlands the freshwater communities are less effective in this regard. Nonvegetated wetlands are also effective erosion buffers al- though they function in a different manner from the marshes. For example, a broad, gently sloping sand beach is an excellent wave energy dissipator and large intertidal bars and flats serve to "trip" waves as they move shoreward thus reducing their energy before they strike the shoreline. The disruption of nearshore intertidal areas may increase wave energy striking the adjacent shoreline thus accelerating ero- sion there. D. Water Quality Control. The dense growth of some marshes acts as a filter, trapping upland sediment before it reaches 4 Wetlands Guidelines waterways and thus protecting shellfish beds and navigation channels from siltation. Marshes can also filter out sedi- ments that are already in the water column. The ability of marshes to filter sediments and maintain water clarity is of particular importance to the maintenance of clam and oyster production. Some marshes have been shown to act as sinks or traps for other pollutants and marsh plants take up nutri- ents deposited in marsh soils. Excess nutrient levels in an es- tuary can be a problem but the exact role of marshes in nutrient removal is not yet fully understood. Nonvegetated wetlands are also important in the cycling of nutrients in the estuary and the filter feeding organisms pre- sent, particularly on tidal flats, remove suspended solids from the water column in amounts that may significantly af- fect water clarity. E. Flood Buffer. The peat substratum of some marshes acts as a giant sponge in receiving and releasing water. This charac- teristic is an effective buffer against coastal flooding, the ef- fectiveness of which is a function of marsh type and size. The higher elevation marshes are the more effective flood buffers. Nonvegetated wetlands, because of their intertidal location have little value in this regard. The following descriptions of wetland community types are iden- tified and presented for management purposes. The first twelve of these are the vegetated wetlands and of these the first ten are characterized by a single dominant species of emergent vegeta- tion. The term "dominant" is defined here to mean at least 50% of the vegetated surface of the marsh is covered by a single plant species. Types eleven and twelve are brackish and fresh- water marshes which have no clearly dominant species of vegeta- tion. The five types of nonvegetated wetlands described here are iden- tified mainly by physiographic position and sediment composi- tion. No attempt is made to quantitatively separate the communities by particle size dominance since this is not neces- sary for value judgements on the level described in this publica- tipn. 5 Wetlands Guidelines SALTMARSH CORDGRASS Spartina alterniflora 4 K A?t:4, 7 3 to 6 feet high 6 Wetlands Guidelines Type 1. Saltmarsh Cordgrass Community Dominant vegetation: Saltmarsh cordgrass (Spartina alterni- flora Loisel). Associated vegetation: Saltmeadow hay, saltgrass, black nee- dlerush, saltwort, sea lavender, marsh elder, groundsel tree, sea oxeye. Growth habit: Stout, erect grass; long, smooth leaves, often with attached periwinkle snails; located at the waters edge. Tall form 4 to 6 feet along the water; short form 1 to 2 feet at or slightly higher than MHW. Physiographic position: Ranges from mean sea level to ap- proximately mean high water. Average density: Usually 20 plants per square foot. Can range from 10 to 50 plants. Annual production and detritus availability: Average yield is about 4 tons per acre per annum; optimum growth up to 10 tons per acre. Daily tides flux nearly throughout this community. Available detritus to the marine environ- ment is optimum. This type of marsh is recognized as an important spawning and nursery ground for fish. Waterfowl and wildlife utility: Roots and rhizomes eaten by waterfowl. Stems used in muskrat lodge construction. Nest- ing material for Forsters tern, clapper rail and willet. Potential erosion buffer: Most salt marshes and brackish water marshes are bordered by saltmarsh cordgrass along the waters edge. A marsh/water interface of this type is highly desirable as a deterrent to shoreline erosion. Under- lying peat with a vast network of rhizomes and roots is very resistant to wave energy. Water quality control and flood buffer: Marshes of this type can also serve as traps for sediment that originate from upland runoff. This also includes large debris that may accumulate on the marsh surface. SU'NOIARY: Considering the many attributes of this type of marsh community, its conservation should be of highest pri- ority. 7 Wetlands Guidelines SALTMEADOW HAY or SALTMEADOW CORDGRASS SALT GRASS Spartina patMs Distichlis spicata a b b 1 to 3 1 to 3 feet feet high high a. Flowering or fruiting head. a. Flowering or fruiting head. b. Leaves arranged in 3 or more b. Leaves arranged in one planes. plane. Wetlands Guidelines Type 11. Saltmeadow Community Dominant vegetation: Saltmeadow hay (Spartina patens (L.) Greene) Saltgrass (Distichlis spicata (L.) Greene). Associated vegetation: Saltmarsh cordgrass, black nee- dlerush, marsh elder, groundsel tree, saltwort, sea oxeye. Growth habit: Matted meadow-like stands with swirls or "cow- licks," individual plants wiry in appearance; saltgrass 1-2 feet high. Physiographic position: About mean high tide to the limit of spring tides; saltgrass at lower elevations, saltmeadow hay predominates at the higher end of the range. Average density: Mixed populations; 50-150 stems per square foot. Annual production and detritus availability: Ranges from 1-3 tons per acre annum. Only small amounts of dead plant material are flushed out during storms and spring tides. Waterfowl and wildlife utility: Seeds eaten by birds; pro- vides nesting area. Habitat for a snail (Melampus) impor- tant as food for birds. Potential erosion buffer: Effective erosion deterrent at higher elevations. Water quality control and flood buffer: In many cases, this community represents the oldest part of a marsh system. Peat may accumulate to great depths, making this type of marsh act as a giant sponge when flood waters wash over it. Denseness of vegetation and deep peat filter sediments and waste material. SUMNURY: This system is an excellent buffer, filtering out sediments and wastes and absorbing runoff water originat- ing in the uplands. Production and detritus are less impor- tant to the marine environment than in Type I communities. Its contributions tend to favor the upland en- vironment. Its values rank somewhat below Type I but, nevertheless, a Type Il marsh should not be unnecessarily disturbed. 9 Wetlands Guidelines NEEDLERUSH Juncus roemerianus x 3 to 4 feet high 10 Wetlands Guidelines Type III. Black Needlerush Community Dominant vegetation: Black needlerush (Juncus roemerianus Scheele.) Associated vegetation: Usually pure stands with saltmarsh cordgrass, saltgrass and saltmeadow hay near the margin. Growth habit: Dense monospecific stands; plant leafless, cylin- drical hard stems tapering to a sharp pointed tip; brown to dark green in color, 3 to 5 feet high. Physiographic position: About mean high water to some- what below spring tide limit. Seems to prefer sandy sub- stratum. Average density: 30 to 50 stems per square foot. Annual production and detritus availability: 3 to 5 tons per acre per annum, decomposes more slowly than most of the marsh grasses. Not flushed daily by tides. Waterfowl and wildlife utility: There is no evidence that wa- terfowl or wildlife utilize this type of plant directly as a food. Because of the dense, stiff stands, it has little wildlife value except for limited cover. Potential erosion buffer: The dense system of rhizomes and roots of black needlerush are highly resistant to erosion. On sandy shores and low sand berms which support this community type, this characteristic is of high value. Water quality control and t1ood buffer: An effective trap for suspended sediments, but less effective than the densely matted saltmeadow community. Provides effective absorb- ent areas to buffer coastal flooding. SUMMARY: As a single monospecific community this type would support less wildlife diversity than Type I and Il. It functions well as a sediment trap and erosion deterrent but ranks lower than the preceding types. The rhizomes of black needlerush are harder and tougher than the grasses that dominate Types I and Il communities; therefore, nee- dlerush is useful as an erosion deterrent. Overall, the val- ues of this marsh type rank below Types I and 11. Wetlands Guidelines MARSH ELDER GROUNSELTREE Iva frutescens Baccharis hamilifolia V A"", A ,x a a- OV 3 to 10 feet high 3 to 10 feet high a. Leaves thick and fleshy. a. Leaves alternate on stem. b. Leaves opposite each other on the stem. Awl tx ff, 12 Wetlands Guidelines Type IV. Saltbush (Gallbush) Community Dominant vegetation: Groundsel tree, highwater bush (Bac- charis halimifolia L.), marsh elder saltwater bush (Iva frutescens L.) Associated vegetation: Saltmeadow hay, saltgrass, wax myr- tle, sea oxeye. Growth habit: Shrubs 3 to 10 feet high along the margin of the marsh and upland plant communities. Physiographic position: Lower limit is approximately the up- per limit of marsh (marsh-upland ecotone). Average density: May provide dense canopy over marsh. Indi- vidual shrub trunks usually spaced 3 to 10 feet apart. Annual production and detritus availability: Probably less than 2 tons per acre per annum. Detritus of little value. Waterfowl and wildlife utility: Provides diversity for wildlife in general and especially as a nesting area for small birds. No significant food value. Potential erosion buffer: Although not structurally suited as an assimilator of sediment and flood waters, it serves some- what as a buffer to erosion on sand berms that often front small pocket marshes. Also functional as a trap for larger flotsam. Water quality control and flood buffer: Of minor conse- quence, but does trap larger material. (See above). SUMAL4,RY: Useful as an indicator of upper limits of marshes as defined in the Wetlands Act. Values of this type rank be- low that of the preceding types. However, this community does add diversity to the marsh ecosystem. 13 Wetlands Guidelines BIG CORDGRA.SS Spartina cynosuroides T. 4j, 14 Wetlands Guidelines Type V. Big Cordgrass Community Dominant vegetation: Big cordgrass (Spartina cynosuroides (L.) Roth.) Associated vegetation: Usually pure stands. Growth habit: Very tall (6-12 feet), heavily stemmed, leafy grass with distinct branched fruiting head in the fall. Physiographic position: At or slightly above mean high water and extending to the upland margin. Most common in brackish or lower salinity marshes. Average density: 10 to 15 stems per square foot. Annual production and detritus availability: 3 to 6 tons per acre per annum. Detritus accessible only on spring or wind tide, however is rivaled only by saltmarsh cordgrass, which gives big cordgrass a higher value in the context of production than other grasses found above mean high tide. Decomposes more slowly than saltmarsh cordgrass. Waterfowl and wildlife utility: Utilized as a habitat by small animals, often used for muskrat lodges. Geese often eat its rhizomes. Potential erosion buffer: The large, coarse rhizomes and in- tertwining roots stabilize peat along marsh edges. Water quality control and flood buffer: Usually this com- munity type occupies the older parts of a marsh system where peat may be deeper increasing its capacity as a flood water assimilator. It is also useful in trapping flotsam. SUMMARY: Although the elevation occupied by this commu- nity type is similar to that of the saltmeadow community, big cordgrass has a much higher yield of organic matter which likely contributes to the marine food web. It is also relatively high in value as a wildlife food as well as a buffer to erosion. 15 Wetlands Guidelines COMMON or BROAD-LEAVED NARROW-LEAVED CATTAIL CATTAIL Typha angustifolia Typha latifolia X:V, j,; 4@ P, F@ A ilk 3 04 14 16 Wetlands Guidelines Type V1. Cattail Community Dominant vegetation: Narrowleaf cattail (Typha angustifolia L.) Associated vegetation: Broadleaf cattail (Typha latifolia L.), sedges, bulrushes, arrow arum, pickerel weed, smartweed, other fresh or brackish water plants. Growth habit: Characteristie'Viener on a stick"fruiting heads, long strap-like leaves, somewhat blunted tips. 4 to 6 feet tall. Physiographic position: Very wet sites, sometimes in stand- ing water, often at the margin of marsh and uplands. Does well in seepage areas resulting from upland runoff. Average density: 2 to 6 stalks per square foot. Annual production and detritus availability: 2 to 4 tons per acre. Detritus usually not readily accessible to the ma- rine environment. Waterfowl and wildlife utility: Provides habitat for certain birds; roots consumed by muskrats. Potential erosion buffer: Because of its preferred habitat and its characteristic shallow root system, Type VI is only a mi- nor buffer to erosion. Water quality control and flood buffer: Its usual habitat along the upland margins in soft muddy areas ranks this marsh type high as a sediment trap despite its shallow rooted condition. Very few species will grow in these areas either because of the stagnant condition of the substratum or because they are inhibited by toxin release of the cattail roots or a combination of the two factors. SUNEMIARY: Because of its value as a wildlife food and habitat, its function as a sediment trap, its relatively high produc- tion and the usual soft substratum, this type of marsh com- munity should not be indiscriminately used as a development site. As far as overall value is concerned it compares with a saltmeadow marsh (Type 11). 17 Wetlands Guidelines PICKEREL WEED ARROW ARUM Pontederia cordata Peltandra virginica a a W., N b a. Blue flower head. a. Flower head. b. Fruiting head. 18 Wetlands Guidelines Type V11. Arrow Arum-Pickerel Weed Community Dominant vegetation: Arrow arum (Peltandra virginica (L.) Kunth.) Pickerel weed Pontederia cordata L.) Associated vegetation: Sedges, smartweeds, bulrushes, ferns, cattails, pond lily. Growth habit: Many broad leaved clumps growing from a thick, cylindrical rhizome; arrow or heart shaped leaves. Clumps 2 to 6 feet tall, average height 3 feet. Physiographic position: On tidal mud flats from mean sea level to about mean high tide in low salinity or freshwater marshes. Average density: 1 or 2 clumps per 10 square feet. Annual production and detritus availability: 2 to 4 tons per acre. Detritus readily available to the marine food web because of daily tide fluxes. In the fall of the year these spe- cies decompose quite rapidly and completely except for the root stock. Waterfowl and wildlife utility: Seeds and shoots of both spe- cies are eaten by ducks. Arrow arum seeds float after the pod decays and are readily available for wood ducks. Often associated with confirmed spawning and nursery areas for herring and shad. Potential erosion buffer: Although this community type lacks the vast network of rhizomes, roots and peat substra- tum typical of a saltmarsh cordgrass community, this marsh/water interface vegetation is often the only vegeta- tive buffer to shoreline erosion in freshwater areas. The substratum in a marsh such as this is typically often, un- stable mud. After the vegetation has decayed in the winter time, the mud flats are highly susceptible to erosion due to winter rains. Water quality control and flood buffer: Slows the flow of flood waters, causing some suspended sediment to settle out. SUAUdARY: Under natural conditions the marsh of this type is relatively stable but is highly sensitive to development and activities such as excessive boat traffic. Because of its many attributes this marsh ranks similar to that of Type 1. 19 Wetlands Guidelines REED GRASS Phragmites australis i@@ ol N 20 Wetlands Guidelines Type V111. Reed Grass Community Dominant vegetation: Reed grass (Phragmites australis) for- merly (Phragmites communes Trinius) Associated species: Switch grass, saltbushes, a few others. Growth habit: Tall stiff grass with short, wide leaves tapering abruptly to a point; soft plume-like seed head. 6 to 10 feet high. Physiographic position: Usually above mean high tide, drier areas on disturbed sites. Average density: 3 to 6 stems per square foot. Annual production and detritus availability: 4 to 6 tons per acre, detritus seldom available except in storm condi- tions. Waterfowl and wildlife utility: Little direct value to wildlife except as cover. May have a detrimental effect in that it can invade areas of a marsh and compete with desirable species. It appears to be replacing big cordgrass and other plants in freshwater marshes of the Pamunkey River. Potential erosion buffer: Good erosion deterrent on dis- turbed sites, especially on spoil. Water quality control and flood buffer: Valuable as a buff- er to erosion. Potential as sediment trap and flood deter- rent appears to be minimal. SUAUdARY: This plant is a relatively recent invader in Vir- ginia but is spreading rapidly, often displacing more impor- tant marsh plants. It has little or no value to wildlife in general. Its only important value would be its function as a stabilizer on dredge spoil. This community type ranks be- low a Type III marsh, the black needlerush community. 21 Wetlands Gpidelines YELLOW POND LILY -Naphur luteum 7@@ .. .. .... ... ------- --- 22 Wetlands Guidelines Type EK. Yellow Pond Lily Community Dominant vegetation: Yellow pond lily, spatter-dock (Nuphar luteum (L. Sibthrop and Smith) Associated vegetation: Pickerel weed, arrow ar um. Growth habit: Saucer shaped leaves with a narrow notch, floating on water; large, leathery yellow flower. 2 to 4 feet high from submerged root stalk. Physiographic position: Submerged except for floating leaves at high tide. Found in freshwater areas. Average density: One plant (cluster of leaves) for every 3 to 5 square feet. Annual production and detritus availability: To 1 ton per acre; detritus readily available but not a significant con- tributor to the food chain. Waterfowl utility: Excellent cover and attachment site for aquatic animals and algae. Feeding territory for aquatic birds and fish. Potential erosion buffer: While lacking the stiffness of grasses and sedges, these plants do reduce wave action from wind and boats. This has been noted in freshwater streams and boat channels. Water quality control and flood buffer: Although not a di- rect assimilator of sediments and flood waters, the flow of flood water is slowed somewhat and sediments can settle out. This function is minimal because the community is submerged completely in flood conditions. SUAMARY: Destruction of the community would result in a de- crease in number and diversity of aquatic animal life in the immediate area. The greatest value the community has is its habitat for aquatic biota. This type should be ranked with or slightly higher than a Type III (black needlerush) marsh. 23 Wetlands Guidelines SALTWORT Salicornia sp. L A 61, 24 Wetlands Guidelines Type X. Saltwort Community Dominant vegetation: Saltwort, glasswort (Salicornia sp.) Associated vegetation: Saltmarsh cordgrass, saltgrass, sea lavender. Growth habit: Leafless green fleshy-stemmed plant, red in color in fall, 8 inches to 1 feet tall. Physiographic position: Above mean high tide in pannes or sparsely vegetated areas. Average density: 10 to 15 stems per square foot. Annual production and detritus availability: Less than 1/2 ton per acre. Exerts very little influence on the marine en- vironment. Wildlife and waterfowl utility: Some evidence that stems are eaten by ducks. May be a feeding area for other marsh birds. Potential erosion buffer: Has very little value as an erosion deterrent. Water quality control and flood buffer: Because of the char- acter of the stem, a shallow root system and the usual small sizes of the populations, these community types have little or no value in this category. SLTAU4ARY: This community is not high in value. It usually oc- cupies small areas within larger more productive marshes and can be used as an indicator of higher marsh elevations. 25 Wetlands Guidelines FRESHWATER MDCED COMMUNITY - TYPE XI (excluding upland species - pines, cedars, etc.) Buttonbush Yellow Pond Lily Type.IX Big Cordgrass. Type V Arrow Arum and Pickerel Weed Wild Rice Type VII Cattail Smartweed and Type VI Waterdock Swamp Milkweed Sedges 26 Wetlands Guidelines Type XI. Freshwater Mixed Community Dominant vegetation: No single species covers more than 50% of the site. Associated vegetation: Bulrushes, sedges, waterdock, smart- weeds, ferns, pickerel weed, arrow arum, wildrice beggar's ticks, rice cutgrass. Growth habit: Heterogeneous mixture of plants. Physiographic position: From submerged to the upper limits of the wetlands. Average density: Highly variable. Annual production and detritus availability: 3 to 5 tons per acre. Detritus of species such as arrow arum, pickerel weed and yellow pond lily would be available in the interti- dal zone. Waterfowl and wildlife utility: A highly valuable marsh for a broad diversity in wildlife species. Plant species such as smartweeds, waterdock, wildrice and others are prime wa- terfowl and sora rail foods. Waters adjacent to these type marshes are also known as spawning and nursery grounds for striped bass, shad and river herring. Potential erosion buffer: Shoreline erosion protection pro- vided by this type of marsh is equivalent to Type VII, ar- row arum - pickerel weed community. Water quality control and flood buffer: This ranks some- what higher as a sediment trap and flood deterrent than an arrow arum - pickerel weed community. The presence of the stiffer, more resilient grasses, sedges and rushes and peaty-type substratum increases the ability of this type of community over a Type VII marsh as an assimilator of sedi- ments and flood waters. SUMIARY. Th6se are very valuable marshes and the aim should be to keep them in a natural state, This type of marsh would be ranked equivalent to a saltmarsh cordgrass marsh (Type I) and an arrow arum - pickerel weed (Type VII) marsh. 27 Wetlands Guidelines BRACKISH WATER MIXED COMMUNITY - TYPE XII (excluding upland species - pines, cedars, etc.) Saltbush Saltmarsh Cordgrass Type IV Type I Big Cordgrass Black Needlerush Type V Type III SaItgrass Meadow Saltmarsh Bulrush Type II Olney Threesquare Sea Lavender 28 Wetlands Guidelines Type XII. Brackish Water Mixed Community Dominant vegetation: No single species covers more than 50% of the site. Associated vegetation: Saltmarsh cordgrass, saltmeadow hay, saltgrass, black needlerush, saltbushes, threesquares, big cordgrass, cattails. Growth habit: Heterogeneous mixture of plants in wet areas. Physiographic position: Extending from about mean sea level to the upland margin. Average density: Highly variable. Annual productivity and detritus availability: 3 to 4 tons per acre, detritus readily available in the intertidal zone. Waterfowl and wildlife utility: Wide diversity of vegetation provides a variety of wildlife food. Waterfowl foods are plen- tiful, such as the generous seed heads of saltmarsh bulrush. Potential erosion buffer: Shoreline erosion protection is the same as that of a Type I marsh (saltmarsh cordgrass). Most brackish water marshes are bordered by saltmarsh cordgrass. Water quality control and flood buffer: Ranks high in this category, having similar attributes as a Type 11 marsh (saltmeadow). SUMAURY: This marsh is a microcosm of all the communities found in saline waters. Brackish water marshes are known spawning and nursery grounds. This community type con- tains valuable food and habitat for a wide diversity of wild- life species. Ranks with a Type I (saltmarsh cordgrass) marsh. 29 Wetlands Guidelines DOMINANT BENTHIC SPECIES OF THE NON-VEGETATEDNETLAND COMMUNITIES IntertidAl Oyster Intertidal Teach Tidal Flat Reef Community Community Community SEDIMENT TYPE SAND SAND SAND/MUD MUD SHELL DOMINANT Amphipods . Amphipods Mud snails Mud snails Oysters SPECIES Mole crabs Bloodworms Soft clams Bloodworms Hard clams Donax clams Soft clams Razor clams Razor clams Curved mussels Razor clams Spionid worms Spionid worms Arnphipods Sandworms Hard clams Mud crabs A. rso B.. R D G. K Lk SPECIES A. Mole crab (Emer@ita talpoida) F. Spionid worm (Polydora ligni) INDEX B. Haustorid amphipod G. Donax clam (Donax variabilius) (Parahaustorius) H. Mud snail (11yanassa obsoleta) C. Haustorid amphipod I. Bloodworin (Glycera dibranchiata) (Parahaustorius) J. Curved mussel (Isochodium recurvus) D. Sandworin (Nereid polycheate) K. Razor clam (Tagelus plubeus) E. Soft clam (Mya arenaria) L. Oyster (Crassostrea virginica) G.R 30 Wetlands Guidelines Type X111. Intertidal Beach Community Dominant species: Ocean Beach - Mole crabs, Donax clam, Haustorid amphipods Bay Beach - Haustorid amphipods, oligochaete worms, beach fleas Associated species: Ghost crabs, polychaete worms, razor clams Growth habit: Most organisms buried just below the sand sur- face. Constantly being uncovered by waves and burrowing back into sand. Most species are annuals. Average density: Highly variable, animals move up and down beach with tide level. In warmer months densities can aver age 100 to 5000 individuals/m2 . Annual production is very high. Primary production and nutrient cycling: Relatively low compared to marshes and tidal flats because of high wave energy. Habitat value: Very important foraging area for many shore- birds areas above mean high water are used as nesting sites by terns and skimmers. Fish utilize area for feeding during high tide. Erosion buffer: Beach is an ideal natural wave-energy dissipa- tor. It interacts with noarshore sand bars and dunes. Its most important ecological function to man is to buffer the effects of storm waves. SLTAUdARY: Beach systems deserve the hig hest order of protec- tion particularly when associated with extensive dunes and nearshore sandbars. 31 Wetlands Guidelines Type XIV. Sand Flat.Community Dominant species: Sandworm, bloodworm, amphipods, soft clams, razor clams. Associated species: Other polychaete worms, hiollusks and phoronid worms. Growth habi t: Most of the inhabitants are surface and deep burrowing species; some are permanent tube builders. Most species are annuals,or biannuals, several reproduce throughout the warm weather period. There is a fairly rapid turnover of individuals due to predation so the aver- age size of organisms is small'. Average densit@: Highly variable with polychaete worms reaching higher densities than other groups. Densities of major invertebrate. groups range from 330 to 3000 ind. /M2 Primar , y production: Annual production ranges from 100 to 200 g C/n12 . This is lower than that of marshes but only slightly less than other tidal flats. The primary production of tl@is community enters the estuarine food web directly via grazing. This is more efficient than the detrital food chain where decomposition in an intermediate step. The large particle size of sand and lower percentage of organics reduces the role of this community type in nutrient recy- cling. Habitat value: Very important as nursery and feeding area for fishes and blue crabs. Important shorebird feeding area. May support high shellfish populations. Erosion buffer: Important in reducing wave energy and thus erosion potential on adjacent shorelines. SUNEWARY: Overall, the ecological value of this community rates only slightly below beaches, oyster reefs and Group I marshes. 32 Wetlands Guidelines Type XV. Sand/Mud Mixed Flat Community Dominant species: Hard clams, parchment worms, Spionid polychaetes, soft clams, razor clams and mud snails. Associated species: Other polychaetes, molluscs, crustaceans, acorn worms, Phoronid worms. Growth habit: This community is populated in general by many surface and deep burrowers, and permanent tube builders. Otherwise similar to sand flats. Average density: Highly variable but overall higher than sand flats or mud flats. Densities range from 5300 to 8300 indi- 2 viduals/m Primary production and nutrient cycling: Primary produc- tion in this community is very similar to sand flats. Since the organic matter content of the sediments is higher than that of sand flats, secondary, microbial production may be higher and this augments the primary production. This community probably interacts with estuarine nutrient cy- cles to a greater extent than sand flats. Habitat value: This community is a very important area for wading birds, shorebirds and other other migratory water- fowl. It is heavily used by important commercial and sports fishes for feeding and is important blue crab habitat. The habitat value may increase in importance when a marsh is adjacent due to higher organic content in the sediments and the habitat variety provided by the marsh. Erosion buffer: Slows wave velocity and thus may reduce wave erosion impinging on adjacent shoreline. SUAMARY: Overall this community has very high habitat val- ues especially if associated with marshes. Ranks only slightly below beaches and intertidal oyster reefs. 33 Wetlands Guidelines Type XV1. Mud Flat Community Dominant species: Spionid worms, mud snails, razor clams, bloodworms. Associated species: Other polychaetes, molluscs and crusta- ceans. Growth habit: Surface and shallow burrowing organisms pre- dominate in this community type. Some permanent tube builders may be present. Problems with sediment stability limit species to mainly surface detrital feeders. Average density: Highly variable; Generally densities are slightly lower than mixed flats but higher than sand/flats with a range of 50 to 5000 individuals/m2. Primary production and nutrient cycling: The areal extent of mud flats is probably equal to or greater than the total for marshes. Primary production is probably the highest of the nonvegetated communities. Mud flats interact signifi- cantly with adjacent vegetated areas in the cycling of nutri- ents. Where mudflats and marshes occur together they are. mutually dependent. Ecologically, each is an extension of the other. Habitat value: Highly important foraging area for waterfowl, sports and commercial fishes and Many other species of food chain value in the marine ecosystem. Erosion buffer: Since this community is generally only found in quiescent areas it has less value in this regard than sand or mixed flats. SUAUdARY: The overall ecological value of mud flats is compa- rable to sand flats and mixed flats. It is probably'most im- portant in nutrient cycling of the three. 34 Wetlands Guidelines Type XVIL Intertidal Oyster Reef Community Dominant species: Oysters, hard clams, sand worms, am- phipods, mud crabs. Associated species: Other polychaetes, mud snails, curved mussels, barnacles, sponges, hydroids, razor clams, other molluscs and crustaceans. Growth habit: Oyster shells provide increased diversity of habitats for a variety of estuarine species. This community is characterized by high diversity of attached and associ- ated organisms. Average density: Oysters dominate when area managed by man, Otherwise the reef is dominated by fouling organisms as listed above. Highly variable density but generally greater than other flats. Primary productivity and nutrient cycling: Very little data are available concerning the primary production of oyster reefs. Given the high habitat and animal diversity however, it is probable that primary production is at least as high as other nonvegetated communities. Habitat value: Very high; many important food chain organ- isms associated. This community is heavily utilized by blue crabs and fishes during high tides. Very high diversity and secondary productivity. Erosion buffer: Shells cemented together may be important in dissipating waves and may resist shoreline erosive forces. SUNBURY: Overall ecological value very high. This coramu- nity is an excellent habitat with high diversity. 35 Wetlands Guidelines . 36 Wetlands Guidelines Section III Evaluation of Wetlands Types For management purposes, th'e twelve types of vegetated wet- lands (marshes) and five types of nonvegetated wetlands (tidal flats and beaches) identified in Section II are grouped into five classifications based on the estimated total environmental value of an acre of each type. The reader is cautioned however that these groupings are based on average values and case-by-case analysis may yield differing results. One must also exercise re- straint when comparing vegetated vs. non-vegetated communi- ties. Group One: Vegetated communities Saltmarsh cordgrass (Type I) Arrow arum-pickerel weed (Type VII) Freshwater mixed (Type XI) Brackish water mixed (Type XII) Nonvegetated communities Intertidal beaches (Type XIII) Intertidal oyster reef (Type XVID The vegetated community types in Group One have the highest values in productivity and wildlife utility and are closely associ- ated with fish spawning and nursery areas. They also have high values as erosion inhibitors, are important to shellfish popula- tions and are important factors in nutrient cycling. Intertidal beaches and sand bars have the highest relative val- ues as buffers to shoreline erosion. In addition, they rank very high as marine habitat and in secondary productivity. Intertidal oyster reefs, which occur primarily on the seaside of the Eastern Shore, have their highest values in terms of productivity, habi- tat and commercial importance. All of the communities in the Group One classification merit the highest order of protection. 37 Wetlands Guidelines Group Two; Vegetated communities Big cordgrass (Type V) Saltmeadow (Type II) Cattail (Type VI) Nonvegetated communities Sand/flats (Type XIV) Sand/mud mixed flats (Type XV) Mud/flats (Type XVI) The marshes in Group Two are only slightly less valuable than those in the Croup One classification. The major -differences be- ing the reduced availability of detritus from the Group Two marshes due to physiographic factors. The detritus produced on the Group Two marshes is more likely to accumulate in the marsh and is less available to marine organisms. Group Two marshes have high values in maintaining water quality, buffer- ing coastal flooding, and as habitat. The Group Two, nonvegetated communities have high general productivity values and play an essential role in nutrient cycling in the estuary. They are very important foraging areas for ma- rine birds and many mobile marine organisms of commercial and recreational importance. They have less value than the Group One communities from an erosion and flood buffering standpoint. Group Two wetlandscommunities rank only slightly below those of Group One in overall environmental importance. They deserve an order of protection only slightly below that of the Group One wetlands. Since there are many variables involved in any evaluation scheme, it is highly likely that some Group Two wetlands may on occasion outrank some Group One communi- ties. This may be particularly true of the nonvegetated communi- ties which exhibit a great deal more variability than the vegetated communities. 38 Wetlands Guidelines Group Three: Yellow pond lily (Type IX) Black needlerush (Type III) The two marshes in the Group Three category are quite dissimi- lar in properties. The yellow pond lily marsh is not a significant contributor to the food web but it does have high values to wild- life and waterfowl. Black needlerush has a high productivity fac- tor but a low detritus availability value. Black needlerush has little wildlife value but it ranks high as an erosion and flood buff- er. Group Three marshes are important, though their total val- ues are less than Group One and Two marshes. If development in wetlands is considered necessary, it would be better to alter Group Three marshes than Group One or Two. Group Four: Saltbush (Type IV) The salthush community is valued primarily for the diversity and bird nesting habitat it adds to the marsh ecosystem. To a lesser extent it also acts as an erosion buffer. Group Four marshes should not be unnecessarily disturbed but it would be better to concentrate necessary development in these marshes rather than disturb any of the marshes in the preceding groups. Group Five: Saltwort (Type X) Reedgrass (Type VIII) Based on present information Group Five marshes have only a few values of significance. While Group Five marshes should not be unreasonably disturbed, it is preferable to develop in these marshes than in any of the other types. The ranking system above is only a partial tool for use in rnak- ing decisions to alter wetlands for it measures only one wetland type against another. Other factors, involving a total view of the creek or river system involved, should be considered in the deci- sion making process. Acreage is obviously one important factor to consider when evaluating a specific wetland. A large wetland is inherently more valuable than a smaller wetland of the same type. Many 39 Wetlands Guidelines creeks and rivers in Virginia however, contain vegetated and nonvegetated wetland areas which are quite small and/or frag- mented. The cumulative value of these small areas may be as great or greater than that of a single wetland of the same type and acreage. Any marsh which is *2 feet or more in average width i's consid- ered to have significant values as an erosion deterrent and in fil- tering sediments coming from the uplands. It may also have other values depending upon the total acreage of the marsh par- cel. Any marsh which is greater than 1/10 of an acre in size may have, depending on type and viability, significant values in terms of productivity, detritus availability and wildlife habitat. Depending,on its location, it may also have value as an erosion buffer. In Virginia wetlands represent a little over 1% of the total acre- age in the state yet they play a vital role in sustaining the impor- tant commercial and recreational fisheries which millions of east coast citizens enjoy. Population and development pressures in the tidal portion of Virginia pose a subtle but constant threat to these marine resources. Habitat losses are generally counted in small portions rather than catastrophic leaps. It is very impor- tant to'note that althoughIthe large scale projects attract greater publicity, the total resource loss due to many small pro- jects may be of equal or greater importance from an environ- mental viewpoint. Because of the essential functions performed by wetlands in the marine environment and the limited extent of this resource, it is necessary to limit the activities which adversely affect wetlands to those considered highly essential. If the activity proposed can be accommodated while preserv ing all or most of the wetlands involved, a proper balance has been struck. In cases where devel- opment and preservation are mutually exclusive the necessity of the activity must be weighed against the value of the resource involved and the degree of adverse impact the, activity will have on the wetland. 40 Wetlands Guidelines Section IV Criteria for Evaluating Alterations of Wetlands The legislature established a policy "to preserve the wetlands and to prevent their despoliation and destruction and to accom- modate necessary economic development in a manner consistent with wetlands preservation". This section addresses the forego- ing policy. Many proposed uses of the shoreline can be accommo- dated with little or no loss of wetlands if the following criteria are applied. There are times, of course, when these criteria may not apply in specific cases. The conscientious application of these criteria will, however, materially reduce adverse environ- mental impacts of man's activities on the shoreline. The individual criteria contained in this section are supported by brief statements explaining the basic reasons behind adop- tion of the particular criterion. It is emphasized that these ra- tionale are of necessity very brief and do not encompass all aspects of the given subject. Persons desiring further details should contact either the Virginia Marine Resources Commis- sion, Habitat Management Division or the Virginia Institute of Marine Science, Department of Wetlands Ecology. General Criteria A. Provided significant marine fisheries, wetlands and wildlife resources are not unreasonably detrimentally affected, altera- tion of the shoreline or construction of shoreline facilities may be justified in order to: 1 Gain access to navigable waters by: a. Commercial, industrial, and recreational interests for which it has been clearly demonstrated that wa- terfront facilities are required. b. Owners of land adjacent to waters of navigable depth or waters which can be made navigable with only minimal adverse impact on the environment. 41 Wetland.@ Guidelines 2. Protect property from significant damage or loss due to erosion or.other natural causes. B. Alteration of the shoreline is ordinarily not justified: 1. For purposes or activities which can be conducted on exist- ing fastlands and which have no inherent requirement for access to water resources. 2. For purposes of creating waterfront property from lots and subdivisions which are not naturally contiguous to waters of navigable depth or waters which can only be made navi- gable by substantial alteration or destruction of marine.re- sources. 3. When damage to properties owned by others is a likely re- sult of the proposed activity. 4. When the alteration will result in discharge Qf efhuents which impair wetlands, water quality or other marine re- sources. 5. When there are viable alternatives which can achieve the given purpose without adversely affecting marshes, oyster grounds or other natural resources. Rationale: These criteria recognize riparian rights and re- serve the shoreline for those uses or activities which re- quire water access. These criteria also point out that activities such as dredging into the fastlands for housing developments often have a significant and long term ad- verse impact on the marine environment through such ef- fects as changed upland hydrology, sedimentation, changes in water current patterns near the shoreline, and the introduction of pollutant discharges which frequently lead to closure of shellfish grounds. The dredging of chan- nels into fastlands may also lead to deterioration of ground water by salt water intrusion into aquifers. 42 Wetlands Guidelines C. Utilization of open-pile type structures for gaining access to adequate water depths is generally preferred over the con- struction of solid structure, dredging or filling. Rationale: The construction of solid structures, or the con- duct of dredging and filling operations, often causes irretriev- able loss of wetlands through their direct displacement or by indirect effects of sedimentation or altered water currents. Open-pile type structures permit continued tidal flow over ex- isting wetlands and subtidal areas, avoid potential sedimen- tation problems, future maintenance dredging, and have less effect on existing water current patterns. D. Channels, fills and structures should be designed to with- stand the maximum stresses of the marine environment and also to minimize the frequency of future maintenance activi- ties. Rationale: Shoreline alterations o ften change currents, af- fect shoreline stability and cause biological damage. Unsuc- cessful structures or channels generate demands for remedial action which can compound initial adverse effects. Designs which minimize the dredging frequency in channels are particularly important. Dredging destroys or displaces bottom-dwelling organisms of value to the aquatic food web. Organisms can be expected to recolonize a dredged area after a period of time, however, too frequent dredging can inhibit recolonization. E. High density development in or immediately adjacent to wet- lands and/or other flood plains is discouraged. Rationale: Development in low-lying areas and on high en- ergy coastlines has historically created costly flood control and flood relief problems including claims for indemnifica- tion. Additionally, hydrological changes in surface run-off patterns are caused by the paving over of formerly absorbent soil. The usual effect is an increase in both the amount and the rate of surface water-flow, often contributing to shoreline eros'ion and other problems. Finally, high-density develop- ment leads to a concentration of contaminating constituents 43 Wetlands Guidelines in urban surface water runoff which can severely stress re- ceiving waters in the adjacent marine environment. There ap- pears to be a direct relationship between population density in a watershed and increased bacterial levels in adjacent wa- ters. This may lead to the imposition of long term restric- tions on the direct marketing of shellfish. Specific Criteria The following specific criteria are established for use in the de- sign, evaluation or modification of individual projects. A. Shoreline Protection Strategies 1. Shoreline protection structures are justified only if there is active, detrimental shoreline erosion which cannot be otherwise controlled; if there is rapid sedimentation ad- versely affecting marine life or impairing navigation which cannot be corrected by upland modifications; or if there is a clear and definite need to accrete beaches. Rationale: The'design and placement of shoreline protec- tion structures is, a highly technical subject and often the precise or long-term effects of such structures on littoral processes cannot be predicted. A study of one county's shoreline shows that nearly 50% of the existing.s'horeline protection systems are ineffective or poor in performance. Shoreline protection structures disrupt natural forces and drive a shoreline away from a natural equilibrium state. In short, all protective structures have the potential to ad- versely affect marine resources directly or through indi- rect means. Needless shoreline modification is therefore discouraged. 2. For shorelines experiencing mild to moderate erosion, the planting of marsh grasses is a preferred means of stabiliza- tion, Note: The planting of marsh grasses is not appropri- ate on all shorelines and requires some technical expertise. Free advice is available from the Virginia Shore- 44 Wetlands Guidelines line Advisory Service and the Virginia Institute of Marine Science. Rationale: Fringing marshes buffer erosion through their dense root systems and ability to collect sand and sedi- ments moving along the shoreline. When a fringe marsh is established, it not only provides food and habitat for ma- rine birds and other organisms but also minimizes the ad- verse effects to adjacent shoreline properties which are often associated with other types of erosion control meas- ures. 3. When an erosion control structure, such as a bulkhead or seawall, is deemed necessary, it should ordinarily be placed landward of any existing and productive marsh vegetation. A line of saltbushes, if existing, can usually in- dicate the seaward limit of the vertical structure. Along shorelines where no marsh vegetation exists, the retaining structure should ordinarily be placed far enough landward of mean high water so as to minimize exposure to wave ac- tion. Rationale: A vertical retaining structure behind a marsh not only preserves the marsh for its biological productivity but also utilizes the marsh's capabilities of aiding water quality and deterring erosion. Placing a vertical retaining structure landward of mean high water minimizes its exposure to wave action and re- duces erosion or scour along the toe which could jeopard- ize the integrity of the structure. Landward placement also preserves intertidal bottom, maintaining habitat di- versity and associated functions of this area within the ma- rine ecosystem. 4. Sloped rock or riprap revetments and gabions are gener- ally preferred over vertical structures. 45 Wetlands Guidelines Rationale: Vertical retaining structures tend to reflect wave energy and often transfer a problem to neighboring properties. Coastal waves, whether from natural causes or from boat wakes, are better absorbed or dissipated by riprap revetments or gabio'ns. In addition, the slope and open spaces in riprap or gabion structures may provide suitable habitat for crabs and small fish. In some cases, sediment may be trapped in riprap or gabion structures and subsequently become vegetated with marsh species. 5. The placement of offshore breakwater or submerged, near- shore sills parallel to a portion of shoreline in order to at- tempt to elevate the height of a beach or dampen wave energy is generally acceptable only in areas with a good sand supply in the nearshore zone or where there is active detrimental erosion. Sill structures are usually con- structed of properly filled sandbags, gabions or mortar filled bags. Although not a general rule, the sill is usually most effective when placed at or near the mean low water line. Both breakwaters and sills must be specifically de- signed for the shoreline segment in question. Rationale: The placement of sill structures where there is an insufficient supply of sand to the beach may cause harmful effects to the shorelines of adjacent downdrift properties. Placing the sills at, or near the mean low water line will usually ensure sufficient backshore height; Place- ment of the sill structure too far offshore may result in in- sufficient filling and ultimately failure of the system. Sills. may also not be suitable for high use beaches because of the potential hazard to swimmers. 6. The placement of a groin or series of groins on eroding shorelines in an effort to trap sand and build up a beach is justified only when there is sufficient sand in the littoral drift system or if properly functioning groins Already exist in the section of shoreline in question. 46 Wetlands Guidelines Rationale: Groins are designed to trap sand and build beaches. When they function properly, they necessarily de- prive downdrift shorelines of sand and thus may acceler- ate erosion to adjacent properties particularly if there is only a small amount of sand available in the system. 7. When groins are considered justified they should be low profile in design and only as long as is necessary to trap sand drifting in the littoral zone. Ideal groin length can be determined by examining the sand fillets in existing groins along the same shoreline reach or can be based on the width of the local beach. Rationale: The low profile groin is designed to resemble the natural beach slope and allow sand to by-pass and thus nourish downstream properties once the groin has filled. Groins which are too long for the existing beach may shunt sand out to deeper water thus making it un- available to downdrift properties. 8. The use of jetties at the entrance of a channel in order to maintain navigable depths or protect the entrance from wave attack is justified only when there is a clear and dem- onstrated need for such a structure and adjacent proper- ties will not be significantly adversely affected. Rationale: jetties attempt to prevent the littoral drift from entering the channel by trapping sediment moving along the shoreline. Sand tends to accumulate on the up- drift side of a jetty and sediments are transported away from the jetty on the downdrift; side. This can often result in accelerated erosion of the downdrift shoreline. B. Filling and Dredged Material Disposal. 1. Filling in wetlands or subaqueous areas for the singular purpose of creating waterfront upland property is gener- ally undesirable. 47 Wetlands Guidelines Rationale: Marine resources are finite, provide many valuable services and products and are delicately balanced in an intricate web of biological and physical interactions. Permanent loss of these resources and unnecessary altera- tions jeopardize this delicate ecological balance. 2. When filling along a shoreline is necessary, the activity should be confined to the area landward of any wetlands. If suitable non-wetland areas are not available and it is necessary to locate the fill further seaward, locations in Group 3;-5 wetlands should be selected if possible (reed grass, saltwort, saltbush, black needlerush, yellow pond lily). Every reasonable effort should be made to preserve existing Group 1 and 2 wetlands communities. In nonvege- tated wetlands, fill should be contained at or above the mean high water line. in cases where some encroachment beyond mean high water is justified (e.g. where an eroding -bluff is being graded down to stop erosion), the encroach- ment,channelward of mean high water should be limited to the minimum required to achieve the desired goal. Rationale: The values of the more important wetland communities are preserved, thus somewhat-lessening the undesirable impact of destroying marshes and in the case of nonvegetated areas, minimizing encroachment con- serves these shallow areas to- function as described in Sec- tion II of this document. 3. Fill material, whether on wetlands or nearby fastlands, should not contain contaminants which may leach into ad- jacent waters. Upland source material is generally prefer- able to dredged material for use as fill. Rationale: Oil or other contaminants can leach off the surface of filled areas and travel to adjacent waters via surface runoff. In some instances, they may also leach downward into the water table. In either case, water qual- ity is impaired. Most dredged material is composed of silts 48 Wetlands Guidelines and clays which when dry and compacted do not allow the free flow of water and thus may cause hydraulic flow prob- lems behind a bulkhead. 4. Where feasible, controlled disposal of dredged material on highland property is the preferred method. Rationale: There are many difficulties inherent in control- ling dredged material in the marine environment. Marine resources are finite and subject to significant disruption from such activities since the water column can act as a vector carrying sediments well beyond the immediate dis- posal point. 5. Dredged material disposal areas should meet the following criteria: a. Disposal by the bucket or dragline method: (1) Build an earth-tight bulkhead along the perime- ter of the disposal area sufficient to confine the dredge spoil. The bulkhead or dike (berm) should have a top elevation at least 3 feet above the average upper limit of spring tides. (2) Earthen dikes (berms) should be compacted as they are constructed, have side slopes no steeper than 1 horizontal to 3 vertical, a top width of at least 3 feet, and the toe of the slope should be at least 15 feet from existing marsh grasses. Spillway boxes or release pipes should be provided to prevent water from eroding or over-topping the dike. As soon as possible after completion of the project, the disposal area should be graded and vegetative cover estab- lished. 49 Wetlands Guidelines (3) In some projects involving small volumes of gen- erally sandy material, a double line of staked straw bales may provide suitable containment. b. Disposal by hydraulic methods: (1) Earthen dikes should be constructed by dragline or land fill methods to the specifica- tions as described in 3 (1) above. The volume of the disposal area lying below the elevation of the spillway crest should, at all times during the dredging, be sufficient to provide a retention time long enough to clarify the discharge water to meet applicable water quality standards. The spillway should be placed as far as possible from the discharge end of dredging pipes. (2) The dredge pipeline should have tight joints to prevent leaks. Grading and vegetative cover ,should be accomplished as soon as possible. (It is recognized that hydraulically filled areas may take many months to dry sufficiently for people or equipment to move across them. Seeding may have to be delayed for periods possibly as long asa year. The spillway should therefore be maintained until the area is permanently seeded and vegetation is well established and providing adequate ground cover to retain the soil). Rationale: Control of sedimentation is accom- plished if the above criteria is maintained dur- ing the entire dredging period. 6. Dredged material should not ordinarily be deposited in ad- jacent marsh as a convenience. if it becomes necessary to place spoil on a marsh, consideration should be given to placing it on those portions of lower value or to scattering the material in a thin layer rather than containing it be- 50 Wetlands Guidelines hind a berm. Berms in marshes should be used to contain fill only when absolutely necessary and when they will not impair tidal flow to other wetlands areas. Rationale: A continuous berm often cuts off water supply to a marsh. Selective piling allows continued water supply to uncovered portions of a marsh and may enhance habitat for wildfowl and animals. Scattering of dredged material in a thin layer can sometimes maintain basic marsh val- ues though it may ultimately lead to changes in vegetative species if the marsh surface is significantly raised in eleva- tion. The depth of the soil layer must be evaluated in each case. 7. Whenever feasible, displaced marsh vegetation and peat should be used to reconstitute marsh in the vicinity of the activity site and particularly along the banks of newly cut canals. The practice of compensating for marsh loss in one area by building marsh in another is theoretically viable but because of significant technical difficulties is not al- ways recommended. Rationale: This procedure, when successful, aids in main- taining marsh inventory and will deter shoreline erosion and enhance water quality conditions. 8. When under specific case by case analysis it is determined that marsh creation is an acceptable means of compensat- ing for an unavoidable marsh loss, one marine habitat (e.g. tidal flats) should ordinarily not be sacrificed to cre- ate another (marsh). Resource compensation through marsh creation is not a panacea and should be limited to cases where the loss of existing marsh is unavoidable and significant and there is a high probability of success. Rationale: There is at present no conclusive evidence that the trading of one marine habitat for another results in a net gain for the environment. The creation of marsh from upland or other habitat is technically feasible in 51 Wetlands Guidelines many cases. It is however a complex activity that gener- ally cannot be successfully accomplished without technical knowledge and expertise. 9. Overboard disposal of dredged material is generally unde- sirable unless the deposits are basically clean sand, the disposal area is devoid of comme'rcially important bottom organisms, and the deposits will have a beneficial effect on shoreline erosion problems. There may be occasions when overboard disposal of silty spoil can be used to create marsh. This will probably also entail the planting or seed- ing of marsh vegetation under closely controlled conditions. Rationale: Silty soils tend to stay in the water column longer than the heavier sands and may therefore drift to other areas resulting in damage to bottom organisms out- side the selected spoil area. Pollutants may likewise drift with the currents. In some cases, good quality sand can be beneficial in nourishing starved or eroding beaches and this possibility should be considered, 10. Whenever overboard disposal is permitted, the operation should be located and conducted so as to minimize impacts on commercially important bottom dwelling (benthic) or- ganisms such as clams and oysters, submerged aquatic vegetation, and other unique or highly productive habitats. Rationale: Because water is the link which ties all differ- ent marine habitats together and can transport pollutants ,over large areas, care must be taken to localize the im- pacts of overboard disposal to the maximum extent practi- cal. 11. The overboard disposal of good quality sand in order to re@- plenish beaches is generally acceptable so long. as the beach sand and dredged sand are size-compatible. Rationale: The placement of material of smaller particle size than that found on the natural beach will only serve 52 Wetlands Guidelines to increase turbidity since it will be resuspended by wave action and carried away very quickly resulting in little benefit for the sand-starved beach. C. Dredging 1. When possible, open pile piers should be lengthened to reach necessary water depths in order to minimize the amount of dredging required. Rationale: Open pile piers have a minimal adverse im- pact on the marine environment. Dredging is a significant, though temporary, disruption which must be repeated in order to maintain water depths. Every dredging project, whether new dredging or maintenance requires an ap- proved disposal area and this can be a major problem par- ticularly in developed areas. 2. Dredging for the singular purpose of obtaining fill is ordi- narily not justified. Rationale: Although dredged areas are repopulated to a degree by organisms after cessation of dredging, they gen- erally never return to their predredge productivity levels if water depths are greatly increased. The result is a chronic degradation of habitat quality and reduction in system pro- ductivity. 3. For relatively small projects (2000 c.y. or less), dredging by dragline or bucket method is generally preferred. Rationale: Control of sedimentation is much simpler with the bucket dredge in that there is a higher ratio of soil to water as the dredged material is transferred from the dredging area. Dredged material disposal is less compli- cated and more easily subject to productive use. Hydraulic dredging is preferred for large dredging projects particu- larly when the dredged material is to be placed in an area remote from the dredged site. 53 Wetlands Guidelines 4. The practice of "double handling" dredged material in a waterway is generally undesirable. Rationale: This activity, which involves the interim place- ment of dredged material in the waterway effectively dou- bles the adverse effects of bottom disruption and turbidity associated with dredging activities. 5. Dredging in shellfish areas, beds of subaquatic vegetation and other areas of singularly high productivity should be avoided if possible. Rationale: These areas generally have very high values to both commercial and sport fisheries and to the organ- isms that support them. In addition their recovery period from dredging is measured in years rather than months as is the case for other bottom types. In many cases the new depth involved after dr edging may preclude any recovery of these particular biotic communities. 6. In oyster and clam growing areas (brackish and saline water) dredging should be avoided during the months of July, August, September, December, January and Febr-u- ary, whenever possible. This is particularly important when the dredging is to be performed within 500 yards of, or overboard disposal is within one mile of, productive pub- -lic or privately leased oyster ground. In anadromous fish spawning and nursery areas (i.e. freshwater), dredging and overboard disposal operations should be avoided, when possible, during the period of mid-March through Oc- tober. Particularly critical is the actual spawning period, mid-March through June. Concern is heightened when overboard disposal is involved. Rationale: The majority of oyster spawning and S'patfall occurs during the months of July, August and September in most areas of Virginia. Higher than normal suspended solids levels, which can occur in proximity to large dredg- ing and disposal activities', can interfere with the develop- 54 Wetlands Guidelines ment and survival of oyster larvae. Resultant sedimenta- tion can also adversely affect the setting of oyster larvae by covering clean hard substrates thus making them un- available to the larvae. During the coldest months of the year, oysters are more susceptible to siltation because their pumping activity is reduced and they are less able to clear away rapidly accumulating silt. During the spring spawning run (mid-March through June) anadromous fish eggs and larvae can be adversely affected by higher than normal levels of suspended sediments. Adult migrations can be impeded especially in narrow streams and rivers where turbidity may reach from bank to bank. The period July through October is the nursery period when the lar- vae develop into juveniles before beginning their migra- tion back to the ocean. Note: This guideline is not subject to blanket application in the salinity regimes where it is applicable. Careful case-by-case analysis is required. 7. In relatively large water bodies, overdredging to reduce the frequency of maintenance dredging, should not exceed an additional two feet and this should be based on the an- ticipated sedimentation rate. In narrow canals and other water bodies subject to poor flushing, the dredged depth should not exceed one foot below that of the connecting wa- ters. Rationale: This guideline balances the benefits of re- duced maintenance frequency and thus environmental dis- turbance with the creation of stagnant or' "dead" water which can occur when artificially deep holes are created. Specialized Structures and Activities D. Channeling into Fastland or Marshes 1. Where feasible, community piers and launching facilities are preferable to channeling into fastlands or marshes for water access in conjunction with urban development. 55 Wetlands Guidelines Rationale: Studies have shown that such channeling leads to water quality problems. Poor water circulation and flushing, combined with contaminating constituents and high nutrient loads from adjacent development often leads to reduced dissolved oxygen levels, noxious odors, un- controlled algal growth and fish kills. 2. While environmentally objectionable, there may be times when channels into marshes or uplands are permitted. When this is the case, the following criteria should be ap- plied in order to reduce adverse effects: a. Channels should be short in length and preferably no longer than twice the width. b. Channels should not be dredged more than I foot deeper than the depth of the waterway to which they are to be connected. c. Channels should not be box-cut but should be dredged with slopes that approximate the natural an- gle of repose of soils of the area, usually on the order of 3 feet horizontal for every 1 foot vertical. d. The top banks of channels should be graded to a slight incline anywhere between mean sea level and mean high tide f6r an inland distance of at least 10 feet. This area should then be planted with marsh vegetation appropriate to the soils and the salinity of waters in the area. e. Channels should be significantly shallower at their heads than at their mouths in order to promote bet- ter exchange with the natural waterway. f. Channel curves and angles should be avoided. Rationale: The foregoing criteria reduce the poten- tial adverse impacts of channelization by providing 56 Wetlands Guidelines for better water circulation and bank stability. The marsh vegetation aids in preventing upland spoils and contaminants from lowering water quality. E. Dams and Impoundments 1. Dams and impoundments should ordinarily not be located in tidal wetland areas. If some encroachment into such ar- eas is deemed necessary every effort should be made to limit the encroachment as much as possible and restrict marsh loss to Group 3-5 marshes. Rationale: Impounding an upland area generally involves a tradeoff of one set of upland habitat values (e.g. hard- wood forest) for another set (lake or pond). When tidal wet- lands are lost to this same type of development, the loss to the marine environment can be severe and is generally ir- replaceable. 2. When a dam or impoundment is constructed in, or adja- cent to, a tidal stream, provisions should be incorporated into the design to maintain a flow of freshwater into the es- tuary. Rationale: Maintaining a flow will minimize the up- stream movement of salt water in the stream and thus re- duce large scale aquatic habitat changes due to salinity shift. 3. Dams should incorporate the use of fish ladders in order to minimize the loss of upstream spawning and nursery grounds for marine species. Rationale: Many commercial and sports fishes are spawned and develop to adult stages above the tidal estu- ary. These areas are critical to the maintenance of popula- tion levels in these species. 57 Wetlands Guidelines 4. Techniques which will minimize the possibility of mud- wave creation adjacent to the dam site should be imple- mented when wetlands are present. Rationale: This guideline limits wetland losses due to im- poundments to that immediately in and upstream of the dam site. A mudwave effectively destroys wetlands in its path by raising the substrate elevation above the range of tide. 5. Whenever possible, impoundments should be designed to incorporate shallow water areas capable of supporting emergent vegetation and water tolerant timber. Rationale: Shallow water habitat within the impound- ment can help offset the loss of tidal wetland habitat due to dam construction. F. Marinas 1. Dry storage type facilities are encouraged in preference to wet slip complexes. Rationale: Such facilities minimize adverse impacts to the marine environment and do not occupy space in the water which could be used for recreation by all citizens of the Commonwealth. 2. When siting and designing a marina facility in a coastal 'waterway, the following should be considered: a. All structures should be open-pile or floating with any permanent loss of aquatic habitat limited to that which is absolutely necessary. b. If sited in a small tributary or other poorly circulat- ing body of water,the marina should be situated near the mouth rather than the headwaters. 58 Wetlands Guidelines c. The structures should encroach no more than one third the distance across the waterway except in un- usual channel configurations. d. Marinas should be sited away from productive or ac- tively worked oyster and clam grounds. e. Consideration should be given to the size and depth of the existing waterway and to the number of boats already housed in the vicinity. f. Slips for deep draft vessels should be located in the naturally deeper waters of the marina. g. If the site involves a marsh, all structures except those needed for access (ramps, railways, etc.) should be located landward of or channelward of marsh vege- tation. h. Design of any necessary breakwaters should permit adequate water circulation within the facility to help prevent an accumulation of pollutants. Floating tire or other non-permanent type breakwaters should be considered. Rationale: The foregoing criteria reduce the poten- tial adverse impacts of marinas by providing for bet- ter water circulation, minimizing marine habitat loss, and reducing initial and maintenance dredging requirements. G. Drainage and mosquito ditches 1. Drainage and mosquito ditches should be designed accord- ing to a master plan which will maximize their effective- ness while minimizing their extent as much as possible. 2. Ditches designed along conventional grid patterns are dis- couraged in favor of ditches which link identified mosquito 59 Wetlands Guidelines producing areas within the marsh with tidal waters. Drainage ditches should also be designed to connect to spe- cifically identified, areas of poor drainage. 3. Depths should be limited to no more than 1 foot deeper than the connecting waters. 4. Depending on the size of the ditch, dredging should be ac- complished "in the dry" Gandside to seaward). 5. If dredge spoil must be placed in the marsh, it should be spread or broadcast as thinly as possible over a broad area with no effective elevation change on the marsh surface. If this is not possible, the dredged material should be placed in small widely separated mounds creating plant diversity and allowing water to circulate over the remaining marsh. 6. Where maintenance dredging is to be accomplished, the dredged material should be placed, to the maximum ex- tent possible, on the old spoil area. If this is in the form of a continuous berm paralleling the ditch, the berm should be breached periodically to promote inundation of the re- maining marsh. 7., Rotary ditchers are the preferred means of constructing mosquito ditches and small drainage ditches. Rationale: Adherence to the above procedures will maxi- mize the effectiveness of the ditches while minimizing ad- verse impacts to the wetlands. H. Submarine pipeline crossings 1. Whenever feasible,' pipelines should be placed on piles or attached to existing structure. 2. When a pipeline must be buried in the river bottom, the st ockpiling of excavated material adjacen t; to the trench should be avoided. 60 Wetlands Guidelines 3. When a pipeline must be buried in a marsh, material may be temporarily placed along side the trench if upon comple- tion all excess material is removed from the marsh, the original elevation is restored, and all denuded areas are sprigged with appropriate vegetation. Rationale: These guidelines minimize construction im- pacts to the wetlands and allow for the fastest possible re- covery of the natural system after the disturbance. 61 Wetlands Guidelines 62 Wetlands Guidelines Section V. Wetlands Mitigation-Compensation Policy Definitions The following words, when used in these guidelines, shall have the following meaning unless the context clearly indicates other- wise: "Compensation" means actions taken which have the effect of substituting some form of wetland resource for those lost or sig- nificantly disturbed due to a permitted development activity; gen- erally habitat creation or restoration. Compensation is a form of mitigation. "Mitigation" means all actions, both taken and not taken, which eliminate or materially reduce the adverse effects of a pro- posed activity on the living and nonliving components of a wet- land system or their ability to interact. Policy In spite of the passage of the Virginia Wetlands Act and the Fed- eral Water Pollution Control Act in 1972, the pressures to de- velop lands, including wetlands along Virginia's shoreline, have continued to accelerate as evidenced by the increasing number of permit applications being submitted. At the same time scientific research has demonstrated that certain wetlands can be estab- lished or re-established in areas where wetlands are not found at present. This has led to an increasing number of proposals call- ing for the destruction of wetlands in one area in order to accom- modate development, and the creation of wetlands in another area in order to offset the loss of the natural wetland resource. Although compensating for the loss of a wetland by establishing another of equal or greater area sounds very attractive in theory and has been regarded as successful in a few specific cases, in general, this form of mitigation has proven difficult to success- fq1ly implement. Many questions regarding the ecological sound- 63 Wetl ands Guidelines ness and feasibility of substituting one habitat for another re- main to be answered.. In addition, a number of studies have dem- onstrated that for various reasons the created habitats either never attain the level of productivity or diversity of the natural systems they replace or simply are not capable of performing the ecological functions of the undisturbed habitat. Although California and Oregon now require compensation for lost wetlands on all projects, states such m North Carolina and New Jersey have taken a much more limited approach to the mitigation-compensation question. In general, these latter two states rely on wetland compensation only as a last resort to re- place *wetlands whose loss is highly justified and unavoidable. Virginia to this point has also taken a very conservative tack with regard to the use of wetland compensation as a manage- ment tool. The Commission, and these guidelines, do not require that all wetlands losses be compensated. They do recommend, however, that compensation be required on a limited basis to replace un- avoidable wetlands losses. There are three main reasons for this recommendation. First, a'literature survey and experience with implementing com- pensation on a day-to-day basis reveal a number of significant problems with the concept itself that remain to be resolved. Second, there are general philosophical and technical questions regarding compensation which have not been answered by the scientific community to this.point in time.- Third, and most important, a reading of the Wetlands Act clearly indicates that the General Assembly intended for the Commonwealth's wetland resources to be preserved in their natural state," and emphasized through its declaration of pol- icy, the importance of an overall ecological approach to wetlands mana gement. "The Commonwealth of Virginia hereby recognizes the unique character of the wetlands, an irreplaceable natural resource which, in its natural state, is essential to the ecological sys- 64 Wetlands Guidelines tems of the tidal rivers, bays and estuaries of the Common- wealth." (Emphasis added) The General Assembly also stated that where economic develop- ment in the wetlands is clearly necessary and justified it will be accommodated while preserving the wetlands resource. it is declared to be the public policy of this Commonwealth to preserve the wetlands and to prevent their despoliation and destruction and to accommodate necessary economic de- velopment in a manner consistent with wetlands preserva- tion." (Originally adopted under Section 62.1-13.1 of the Code of Virginia) (Emphasis added) In Section 28.2-1308 of the Code of Virginia the General Assem- bly mandated the preservation of the ecological systems within wetlands of primary ecological significance and then stated: "Development in Tidewater, Virginia, to the maximum extent possible, shall be concentrated in wetlands of lesser ecological significance, in wetlands which have been irreversibly dis- turbed before July one, nineteen hundred seventy-two, and in areas of Tidewater, Virginia, apart from the wetlands." The General Assembly has spelled out clearly that "necessary economic development" is to be accommodated in Tidewater, Vir- ginia, but that the emphasis is on wetlands preservation in their natural state. General Criteria It shall remain the policy of the Commonwealth to mitigate or minimize the loss of wetlands and the adverse ecological effects of all permitted activities through the implementation of the principles set forth in these Wetlands Guidelines which were promulgated in 1974 and revised in 1982. To determine whether compensation is warranted and permissible on a case-by-case ba- sis, however, a two-tiered mechanism will be implemented. This dual approach will consist first of an evaluation of necessity for the proposed wetlands loss (See Specific Criteria). If the pro- posal passes this evaluation, compensation will be required and 65 Wetlands Guidelines implemented as set forth in the second phase, the Supplemental Guidelines. The primary thrust of combining the existing Wetlands Guide- lines with the two-tiered compensation guidelines is to preserve the wetlands as much as'possible in their natural state and to consider appropriate requirements for compensation only after it has been proven that the loss of the natural resource is unavoid- able and that the project will have the highest public and private. benefit. Commitments to preserve other existing wetlands shall not ordinarily be an acceptable form of compensation. Specific Criteria In order for a proposal to be authorized to destroy wetlands and cornpensate for same in some prescribed manner, the three crite- ria listed below must be met. If the proposal cannot meet one or more of these criteria, the activity shall be denied, or must occur in areas apart from the wetlands. Should it satisf3i all three crite- fia, however, compensation for the wetlands lost is'required. 1. All reasonable mitigative actions, including alternate siting, which would eliminate or minimize wetlands loss or distur- bance must be incorporated in the proposal. 2. The proposal must clearly be water-dependent in nature. 3. The propos al must demonstrate clearly its need to be in the wetlands and its overwhelming public and private benefits. Supplemental Guidelines If compensation is required, then the following guidelines should be given due consideration and, if appropriate, may be included as conditions of the permit: A. A detailed plan, including a scaled plan view drawing, shall be submitted describing the objectives of the wetland compen- sation, the type of wetland to be created, the mean tide range at the site, the proposed elevations relative to a tidal datum, the exact location, the. areal extent, the method of marsh es- 66 Wetlands Guidelines tablishment and the exact tim e frame from initial work to completion. B. Once the grading is completed at the planting site, it should be inspected by a competent authority to insure that the ele- vations are appropriate for the vegetation to be planted and that the surface drainage is effective. C. The compensation plan and its implementation must be ac- complished by experienced professionals knowledgeable of the general and site-specific requirements for wetland estab- lishment and long-term survival. D. A performance bond or letter of credit is required and shall remain in force until the new wetland is successfully estab- lished; a minimum of two growing seasons. E. The compensation marsh should be designed to replace as nearly as possible, the functional values of the lost resource on an equal or greater basis. In general this means creating a marsh of similar plant structure to that being lost. This may not be the case where a lesser value marsh is involved (i.e. Group 4 or 5 wetlands). A minimum 1:1 areal exchange is re- quired in any case. F. The compensation should be accomplished prior to, or concur- rently with, the construction of the proposed project. Before any activity under the permit may begin, the permittee must own all interests in the mitigation site which are needed to carry out the mitigation. G. All reasona ble steps must be taken to avoid or minimize any adverse environmental effects associated with the compensa- tion activities themselves. H. On-site compensation is the preferred location alternative with off-site in the same watershed as a consideration when on-site is not possible. Locating a compensation site outside the river basin of the project is not acceptable unless it is done as part of a state-coordinated program of ecological en- hancement. 67 Wetlands Guidelines L In selecting a compensation site, one aquatic community should not be-sacrificed to "create" another. In cases where dredged material must be placed overboard, the area may be used to create marsh, oyster rock or improve the resource value of the bottom. J.. The type of plant community proposed as compensation must have a demonstrated history of successful establishment in or- der to be acceptable. K. The proposed activity should stand on its own merits in the permit review. Compensation should not be used to justify permit issuance. L. Manipulating the plant species composition of an existing marsh community, as a form of compensation, is unaccept- able. M. Nonvegetated wetlands should be treated on an equal basis with vegetated wetlands with regard to compensation and mitigation, unless site-specific information indicates one is more valuable than the other. N. Both short- and long-term monitoring of compensation sites should be considered on a case-by-case basis. For unproven types of compensation the applicant will be responsible for funding such monitoring as is deemed necessary. 0. Where on-site replacement for noncommercial projects is not feasible, compensation for small wetland losses (less than 1,000 sq. ft.) should be avoided in favor of eliminating loss of the natural marsh to the maximum extent possible. P. Conservation or other easements to be held in perpetuity should be required for the compensation marsh. Easements accepted by the Commission will be processed in accordance with the provisions of Section 28.2-1301 of the Code of Vir- ginia. Q. All commercial projects which involve unavoidable wetland losses should be compensated. 68 Wetlands Guidelines Glossary ALGAE - Simple marine or freshwater photosynthetic plants. May be single or multicelled. ANNUALS - Invertebrates which generally spawn once a year and live about a year. BENTHIC - Pertaining to any plant or animal living in or on the bottom sediment of a river, ocean, lake or other aquatic sys- tem. BERM - A wall or mound built around a low-lying area to con- tain a spoil material. BIANNUALS - Invertebrates which generally spawn twice a year and live less than a year. BRACKISH - Pertaining to the waters of bays and estuaries, salty but of lower salinity than seawater. BULKHEAD - A structure or partition, usually running parallel to the shoreline, for the purpose of protecting fastlands from wave action or protecting channels from upland sedi- mentation. COMMUNITY - Ecological term for any naturally occurring group of different organisms inhabiting a common environ- ment, interfacing with each other relatively independent of other groups. Communities may vary in size and larger communities may contain smaller ones. DETRITUS - Organic matter (primarily marsh plants) which while decaying in the aquatic system forms the basis of ma- jor marine food web. The organic matter and its rich growth of microbes are fed on by many estuarine species. DOMINANT - For purposes of classifying marshes in this re- port, any organism which makes up at least 50% by volume. of the organisms present in a given area. DRAGLINE - The method of dredging employing a crane and large metal bucket to remove accumulated sediment. DREDGING IN THE DRY - A technique of dredging used where new channels or canals are being cut. The canal is dredged from the landward end toward the seaward end and the last step is to open the new canal to the existing waterway. 69 Wetlands Guidelines DIKE - A wall or mound built around a low-lying area to pre- vent flooding- ECOLOGY - The overall relationships between organisms and their environment. FASTLANDS - The zone extending from the landward limits of wetlands to at least 400 feet inland. FRESH WATER - Waters containing no appreciable, salt, usu- ally less than .5 parts per thousand. FOOD WEB - The complex interactions of organisms in a natu- ral community involving organisms feeding on one another to obtain energy. GABION -A container filled with stone, brick, shells or other material to give it a heavy weight suitable for use in con- structing bulkheads or groins. In the marine environment, usually made of galvanized steel wire mesh with a PVC (polyvinyl chloride) coating over the galvanizing. GROIN - A shore protection structure built (usually perpendicu- lar to the shoreline) to trap sand and other material mov- ing along the shoreline and thus retard erosion of the shore. HETEROGENEOUS - Being composed of many different forms of something. Specifically, a heterogeneous marsh is one composed of many- different species without any one being dominant. HYDROLOGICAL - Pertaining to water, its properties and dis- tribution especially with reference to water on the surface of the land, in the soil and underlying rock. INTERTIDAL - Area on a shoreline between mean high water and mean low water. JETTY - On open seacoast, a structure extending into a body of water designed to prevent shoaling of a channel by sand or other materials.@ Usually,placed along side channels at en- trances. LINE OF SALTBUSHES - Refers to the characteristic growth of salt marshes at the upper limit of the highest high tides. When present in a line along the inland side of a marsh it often indicates the upper limits of wetlands as'defined in the Virginia Wetlands Act. 70 Wetlands Guidelines LITTORAL PROCESSES - Those physical features and charac- teristics of the intertidal area which determine the type of shoreline present. MICROCOSM - A small community regarded as having all the characteristics of the biosphere or the world. MONOSPECIFIC - Being composed entirely of one species or one type of organism. In this case a marsh vegetated by one type of grass. MEAN HIGH WATER - The average height of high waters over a nineteen year period. MEAN LOW WATER - The average height of low waters over a nineteen year period. PERENNIAL - A plant which produces new growth year after year according to the seasons. In the case of nonwoody plants the aerial portion dies each winter and is replaced each spring. PHYSIOGRAPHIC - A description of nature or natural phenom- ena in general. POPULATION - All of the members of one species within a coni- munity. PRIMARY PRODUCTION - Biomass produced directly from sunlight by plants. PRODUCTIVITY - The rate of energy storage of an ecosystem or community in the form of organic substances which can be used as food materials. RHIZOMES - Underground stems capable of producing new aer- ial shoots. RIPRAP - Refers to a bulkhead or groin constructed of selected rock or concrete forms carefully placed so as to dissipate wave energy (bulkhead) or collect sand (groin) along a shoreline. SECONDARY PRODUCTION - Biomass produced by animals grazing on plants or other organic matter. SHORE DEFENSE STRUCTURES - A bulkhead or groin in- tended to deter erosion of the shoreline. 71 Wetlands Guidelines SPECIES DIVERSITY - Pertaining to the numbers of different species inhabiting a given area, i.e. high species diversity would mean many different species in one area. SPOIL - The material removed from a channel bottom or other body of water during a dredging operation. SPRING TIDES - Higher high tides which occur twice monthly due to astronomical conditions. WRACK LINE - A line of debris, above the mean high tide line, which has been deposited by previous higher than normal tides. 72 . Wetlands Guidelines NOTES 73 Wetlands Guidelines NOTES 74 NOAA COASTAL SERVICES CTR LIBRARY 3 6668 14111702 0-