BOSTON PUBLIC LIBRARY 3 9999 iifi^ii'iiER BEACHES GOVDOC Salt marshes & Tidal Flats pfeperty Ot library Lloyd Center For Environiivental Studies A^ssacKusetts Coastal Zone MaouLgement Prograon Digitized by the Internet Archive in 2011 with funding from Boston Public Library http://www.archive.org/details/barrierbeachessaOOIIoy ■0?: r-llSMC LIBRART BARRIER BEACHES, SALT MARSHES, AND TIDAL FLATS An Inventory of the Coastal Resources of the Commonwealth of Massachusetts by Alan Lee Hankin Lucille Constantine Steve Bliven January 1985 THE LLOYD CENTER FOR ENVIRONMENTAL STUDIES and THE MASSACHUSETTS COASTAL ZONE MANAGEMENT PROGRAM with major assistance from The United States Department of the Interior Fish and Wildlife Service, Region 5 Publication: #13899-27-600-1-85 C.R, Approved by: Daniel Carter, State Purchasing Agent Commonwealth of Massachusetts, Michael S. Dukakis, Governor Executive Office of Environmental Affairs, James S. Hoyte, Secretary Coastal Zone Management Program, Richard F. Delaney, Director ACKNOWLEDGEMENTS Preparation and publication of this document has involved the efforts of several people and organizations. The Lloyd Center and the Massachusetts Coastal Zone Management Program would like to express their special appreciation to the following for their efforts in the planning, research, data collection, and sup- port of this project: - Ralph Tiner and John Organ of the US Department of the Interior, Fish and Wildlife Service, Region V. These two gentlemen made available raw data, maps, equipment, and facilities, as well as their time and expertise to develop the data contained herein, and reviewed drafts of this report. Without their efforts, this project would not have been possible. - Lloyd Center researchers and volunteers David Jansen, Becky Goldstein, and Lisa Caron reviewed preliminary work and the resulting data for accuracy and clarity. - Maronn W. Sternack did the typing and provided the usual cogent comments. While many of the better features of this report came from the above sources, any flaws remain the sole responsibility of the authors, who would appreciate being made aware of them. Alan Lee Hankin Lucille Constantine Lloyd Center for Environmental Studies 430 Potomska Road South Dartmouth, MA 02748 Steve Bliven Massachusetts Coastal Zone Management Office 100 Cambridge Street, 20th Floor Boston, MA 02202 TABLE OF CONTENTS Introduction Salt Marshes Tidal Flats Barrier Beaches References Appendix Page 1 Page 3 Page 1 1 Page 16 Page 24 Page 26 TABLES OF DATA Table 1 Table 2 Table 3 Table 4 Table 5 Table 6 Table 7 Table 8 Table 9 Table 10 State and County Acreage of Three Major Natural Resources Salt Marsh Acreage within Counties Salt Marsh Acreage by Town Comparison of Salt Marsh Acreages in Prior Studies Tidal Flat Acreage within Counties Tidal Flat Acreage by Town Numbers of Barrier Beach Segments and Acreage within Counties Barrier Beach Acreage by Town Size Distribution of Massachusetts Barrier Beaches The 30 Largest Barrier Beach Landforms in Massachusetts Page 2 Page 6 Page 8 Page 10 Page 12 Page 14 Page 18 Page 20 Page 22 Paeje 2 3 - 1 - INTRODUCTION Cities and towns throughout the Commonwealth of Massachusetts have been charged with the primary responsibility for the management of local wetlands resources, particularly through the administration and enforcement of the Massachusetts Wetlands Protection Act (MGL C.131 s. 40). Although some political divisions have inventoried the wetlands within their borders, most do not have quantified information on the amount of resources under their protection. Local Conservation Commissions and Planning Boards are therefore often unaware of the extent of salt marsh, barrier beach, and tidal flat acreage within their juris- diction. Additionally, the regional, county, and state agencies charged with developing broader scale planning, resource protection, and enforcement activi- ties often have difficulty setting priorities for their work. By providing basic information on the extent of some of these coastal wetland .areas , this report seeks to address these problems . The following report will present a quantification of three of the most impor- tant coastal wetland resources in the Commonwealth; salt marshes, tidal flats^ and barrier beaches. For each of these resource areas the report presents a brief introduction to the resource, a discussion of the methodology used in determining the acreage, a discussion of the results, and various tables to pre- sent the data. It is hoped that this study will lead to additional work further defining and analyzing these important resource areas. For further information about the details of this project, data for individual communities, or further projects, please contact the Lloyd Center for Environmental Studies. - 2 - Table 1 STATE AND COUNTY ACREAGE OF THREE MAJOR NATURAL RESOURCES Barrier Beaches Salt Marshes Tidal Flats Massachusetts 18,888.0 48,104.6 41,514.2 Barnstable County 8,723.1 15,201.0 17,808.6 Bristol County 1,008.1 3,748.0 3,130.5 Dukes County 2,135.7 1,027.7 1,258.7 Essex County 2,955.4 18,026.9 6,087.7 Middlesex County 0.0 0.0 0.0 Nantucket County 1,841.7 657.3 136.9 Norfolk County 95.7 1,056.7 2,334.6 Plymouth County 1,933.8 7,400.0 9,369.9 Suffolk County 194.5 987.0 1,387.3 All areas given in acres - 3 - SALT MARSHES Introduction Salt marshes are generally typified by flat, open, grassy areas along tidal waters. They are almost always found in sites protected from the high energy of the open coast; estuaries, salt ponds, or low, entrapped portions of barrier beaches. In Massachusetts' environmental regulations, salt marshes are defined as coastal wetlands "that extend landward up to the highest high tide line, that is the highest spring tide of the year, and are characterized by plants that are well adapted to, or prefer living in, saline soils. Dominant plants within salt marshes are salt meadow cord grass (Spartina patens) and/or salt marsh cord grass (Spartina alternif lora) ." (From the Coastal regulations to the Massachusetts Wetlands Protection Act, MGL C.131, s.40.) Other plant species often found within a salt marsh may include spikegrass (Distichlis spicata), marsh elder (Iva frutescens), saltworts (Sallcornia sp.), and sea lavender (Limonium carolinanum) . Historically viewed as wasted land, salt marshes are now valued for their resource features. They provide wildlife habitat, produce and export large quantities of plant material to nearby waters to form the base of the marine food chain, lessen the effects of storms, take up some water-borne contaminants, and protect ground water from salt intrusion by forming a peat "dam" along the shore. A discussion of salt marsh ecology and resource values may be found in The Ecology of New England High Salt Marshes: A community profile ( 1 ) . Study Methodology Acreage of individual salt marsh segments was taken from National Wetlands Inventory (NWI) maps provided by the US Fish and Wildlife Service (FWS) through their Region V office. These maps are based on US Geological Survey 71/2 minute quadrangle topographic sheets. The wetlands boundaries delineated on these maps were prepared through analysis of aerial photography taken in April of 1977. Classification was based on vegetation, visible hydrology, and geography in accordance with Classification of Wetlands and Deepwater Habitats (2) . All marshes over one-half acre in size are identified and located on the maps. Appendix 1 explains the classification scheme. For the purposes of this study, all areas classified as Estuarine Intertidal Emergent (E2EM) vjere considered to be salt marsh, notwithstanding any further subclassif ication. Areas classified as Estuarine Intertidal Scrub/shrub (E2SS) were listed as shrub marsh. w Each polygon representing E2EM vegetation was located on blackline paper copies from mylar originals. Acreage was measured by tracing each polygon with a Numonics digital read-out planimeter. Each polygon was traced at least twice to ensure accuracy. Data were recorded by quadrangle, city or town, and county. County and state totals are presented in Table 1. Acreages by town within county are found in Table 2. Table 3 lists acreages for all communities in the Commonwealth in sequential order; those communities with the most salt marsh are at the top, those with the least at the bottom. - 4 - Comparison with previous measurements In the past 30 years several measurements have been made of salt marsh acreages in Massachusetts. Results have varied depending on several factors, including: 1- Year of measurement Strong regulatory protection of salt marshes was not enacted until 1963 (the Hatch Act and the Coastal Wetlands Restriction Act) and the current high level of protection under the Coastal Regulations of the Wetlands Protection Act was not implemented until 1978. Prior to this, marshes were still being dredged or filled in significant increments. 2- Methodology of areal measurement The areas of mapped salt marsh units have been calculated using the cell method (dividing the unit into squares of a known area; cells less than half "full" are ignored, those more than half "full" are considered equal to the known area), or by the use of planimeters of varying accuracy. 3- Differences in base map interpretation As discussed below, different methods of aerial photo interpretation and different type and scale of base maps have been used. 4- Different levels of discrimination of polygon size Depending on the purpose of the study, different thresholds for minimum marsh unit size have been used, ranging from 1/2 acre to 40 acres. A brief description of the various prior surveys is provided below. For addi- tional details the reader is directed to the original sources listed under References on Page 24. 1- MacConnell Mapdown (3) Using aerial photography from 1951/1952 and 1971/1972, William MacConnell and his colleagues at the the University of Massachusetts in Amherst mapped the land use of the entire state. Included in the list of 100 categories were tidal marsh (defined as flooded twice daily, primarily Spartina alternif lora) , irregularly flooded salt marsh (flooded at monthly high tides and by storms, primarily Spartina patens and Distichlis spicata) , and salt meadows ditched for mosquito control. MacConnell and his staff made their interpretations of vegetation and land use from 1:20,000 scale black and white aerial photography. In 1951 the minimum land area mapped was 10 acres, for 1971 better photography allowed this to be reduced to 3 acres. A cell, or dot-grid, method was used to calculate areas. 2- US Fish and Wildlife Service Two different types of study that included salt marsh areas have been done by the FWS . In 1954, an evaluation of those Massachusetts wetlands areas significant to waterfowl was done through the Office of River Basin Studies (4) . Using US Geological Survey 71/2 minute quadrangle - 5 topographic sheets, wetland areas of 40 acres or more were identified, delineated, and measured using either a planimeter or the cell method. Figures were provided for both high (Spartina patens and Distichlis spicata) marshes and low (Spartina alternif lora) marshes. A second study was done in 1954 and repeated in 1959 and 1964 to deter- mine vulnerability of wetlands and changes in wetlands areas (5). The minimum threshold size was not stated in the report, but it may have been the same 40 acres as in the above study. The report estimates that 90% of the wetlands in Massachusetts were surveyed. A planimeter was used to measure areas . Table 4 compares the results of these studies at the county and state levels with the results of the work at hand. It is the feeling of the authors that the present study, using recent, accurate mapping, interpretive, and raeasurment techniques provides the most up-to-date, comprehensive definition of Massachusetts' salt marshes. Discussion Almost 70% of Massachusetts' 48,104.6 acres of salt marsh are found in Essex (37.5%) and Barnstable (32%) Counties. In Essex County, marshes make up over 10% of the total land area and within several towns the percentage is signifi- cantly higher. The town of Newbury is 30% marsh (4,646 acres), Salisbury is 25% marsh (2,536 acres), Essex is 24% marsh (2,188 acres), and Ipswich is 21% marsh (4 ,376 acres) . Aptly named Marshfield on the south shore is 13% marsh (2,312 acres) and on Cape Cod (Barnstable County), Orleans and Eastham are each 15% marsh (1377 and 1376 acres respectively) while Barnstable's 4,085 acres of marsh make up 10% of the town. - 6 Table 2 SALT MARSH ACREAGE WITHIN COUNTIES Town Town Area Salt Marsh Shrub Marsh in Acres acreage in acreage in Town Town Barnstable County Barnstable 40,153.6 4,085.1 0.0 Orleans 9,081.6 1,377.0 0.0 Eastham 9,344,0 1,376.2 9.3 Yarmouth 16,339.2 1,230.0 0.0 Dennis 14,016.0 1,138.9 5.5 Sandwich 27,916.8 1,128.2 0.0 Chatham 10,438,4 1,117,1 7.4 Wellfleet 13,324.8 1,039.5 2.4 Harwich 14,342.4 558.2 0.0 Falmouth 29,260.8 529.4 0.0 Brewster 16,102.4 420.5 0.0 Mashpee 16,614.4 337.5 0.0 Provincetown 5,600.0 332.6 0.0 Bourne 26,585.6 297.7 0.0 Truro 13,824.0 233.1 0.0 Totals 262,944.0 15,201.0 24,6 Bristol County Dartmouth 39,558,4 1,143.1 0.0 Westport 35,353.6 1,116.6 0.0 Fairhaven 7,936,0 607.5 0.0 Swansea 14,585,6 184.8 0.0 Dighton 14,304.0 151,4 0.0 Freetown 23,174.4 145,8 0.0 Berkley 10,496,0 125,9 0.0 Somerset 5,446,4 97,3 0.0 Rehoboth 30,374,4 88.5 0.0 Seekonk 11,955,2 52.8 0.0 Acushnet 12,038.4 30,4 0.0 Fall River 2/.,371,2 3,9 0.0 New Bedford 12,691.2 0,0 0.0 Totals 242,284.8 3,748,0 0.0 Dukes County Edgartown 18,720.0 504,1 0.0 Chilmark 14,182.4 241.1 0.0 Gosnold 8,288.0 89.7 0.0 Oak Bluffs 4,640.0 89,3 2.7 Tisbury 4,825,6 53,6 0.0 Gay Head 4,057,6 29.0 6.6 West Tisbury 17,075.2 20.9 0.0 Totals 71,788.8 1,027.7 9.3 - 7 - Essex County Newbury- 15,577.6 4 ,669.5 6.6 Ipswich 21,344.0 4 ,376.0 2.2 Salisbury 10,323.2 2 ,535.5 0.0 Essex 9,203.4 2 ,188.3 0.0 Rowley 12,179.2 1, ,983.3 0.0 Gloucester 16,928.0 1, ,188.1 2.7 Saugus 7,411.2 670.4 0.0 Newburyport 5,702.4 179.9 0.0 Rockport 4,531.2 48.2 0.0 Danvers 8,857.6 34.9 0.0 Nahant 678.4 32.8 0.0 Salem 5,235.2 30.8 0.0 Beverly 9,830.4 29.5 0.0 Manchester 4,940.8 19.1 0.0 Lynn 7,174.4 17.6 0.0 Peabody 10,758.4 9.0 0.0 Ames bury 8,838.4 8.0 0.0 Marblehead 2,828.8 6.0 0.0 Swamps CO tt 1,984.0 0.0 0.0 Totals 164,326.6 18, ,026.9 11.5 Middlesex County Everett 2,400.0 0.0 0.0 Nantucket County Nantucket 32,217.6 657.3 3.7 Norfolk County . Quincy 10,649.6 587.2 0.0 Cohasset 6,438.4 158.4 0.0 Weymouth 11,340.8 157.2 0.0 Milton 8,448.0 147.9 0.0 Braintree 9,222.4 6.0 0.0 Totals 46,099.2 1,056.7 0.0 Plymouth County Marshf ield 18,252.8 2,311.9 0.0 Scituate 10,924.8 1,245.2 0.0 Duxbury 15,686.4 1,093.0 1.7 Wareham 24,339.2 917.0 0.0 Norwell 13,651.2 462.5 0.0 Mattapoiset 11,187.2 349.9 0.0 Marion 9,152.0 305.8 0.0 Plymouth 66,048.0 290.5 0.0 Pembroke 14,886.4 145.4 0.0 Hull 1,619.2 89.6 0.0 Hingham 14,457.6 89.2 3.7 Kingston 12,179.2 83.8 0.0 Hanover 10,003.2 16.2 0.0 Totals 222,387.2 7,4.00.0 5.4 Suffolk County Revere 4,044.8 490.6 0.0 Boston 29,056.0 391.7 0.0 Winthrop 1,043.2 102.7 0.0 Chelsea 1,388.8 2.0 0.0 Totals 35,532.8 987.0 0.0 - 8 - Table 3 SALT MARSH ACREAGE BY TOWN (arranged in descending order) Town County Town Area Salt Marsh Shrub Marsh Newbury ES 15,577.6 4, ,669.5 6.6 Ipswich ES 21,344.0 4. ,376.0 2.2 Barnstable BA 40,153.6 h, ,085.1 0.0 Salisbury ES 10,323.2 2, ,535.5 0.0 Marshf ield PL 18,252.8 2, ,311.9 0.0 Essex ES 9,203.4 2, ,188.3 0.0 Rowley ES 12,179.2 ,983.3 0.0 Orleans BA 9,081.6 ,377.0 0.0 Eastham BA 9,344.0 ,376.2 9.3 Scituate PL 10,924.8 ,245.2 0.0 Yarmouth BA 16,339.2 ,230.0 0.0 Gloucester ES 16,928.0 ,188.1 2.7 Dartmouth BR 39,558.4 ,143.1 0.0 Dennis BA 14,016.0 ,138.9 5.5 Sandwich BA 27,916.8 ,128.2 0.0 Chatham BA 10,438.4 ,117.1 7.4 Westport BR 35,353.6 ,116.6 0.0 Duxbury PL 15,686.4 ,093.0 1.7 Wellfleet BA 13,324.8 ,039.5 2.4 Wareham PL 24,339.2 917.0 0.0 Saugus ES 7,411.2 670.4 0.0 Nantucket NA 32,217.6 657.3 3.7 Fairhaven BR 7,936.0 607.5 0.0 Quincy NO 10,649.6 587.2 0.0 Harwich BA 14,342.4 558.2 0.0 Falmouth BA 29,260.8 529.4 0.0 Edgartown DU 18,720.0 504.1 0.0 Revere SU 4,044.8 490.6 0.0 Norwell PL 13,651.2 462.5 0.0 Brewster BA 16,102.4 420.5 0.0 Boston SU 29,056.0 391.7 0.0 Mattapoiset PL 11,187.2 349.9 0.0 Mashpee BA 16,614.4 337.5 0.0 Provincetown BA 5,600.0 332.6 0.0 Marion PL 9,152.0 305.8 0.0 Bourne BA 26,585.6 297.7 0.0 Plymouth PL 66,048.0 290.5 0.0 Chilmark DU 14,182.4 241.1 0.0 Truro BA 13,824.0 233.1 0.0 Swansea BR 14,585.6 184.8 0.0 All areas given in acres - 9 - SALT MARSH ACREAGE BY TOWN (continued) Town County Town Area Salt Marsh Shrub Marsh Newburyport ES 5,702.4 179.9 0.0 Cohasset NO 6,438.4 158.4 0.0 Weymouth NO 11,340.8 157.2 0.0 Dighton BR 14,304.0 151.4 0.0 Milton NO 8,448.0 147.9 0.0 Freetown BR 23,174.4 145.8 0.0 Pembroke PL 14,886.4 145.4 0.0 Berkley BR 10,496.0 125.9 0.0 Winthrop SU 1,043.2 102.7 0.0 Somerset BR 5,446.4 97.3 0.0 Gosnold DU 8,288.0 89.7 0.0 Hull PL 1,619.2 89.6 0.0 Oak Bluffs DU 4,640.0 89.3 2.7 Hlngham PL 14,457.6 89.2 3.7 Rehoboth BR 30,374.4 88.5 0.0 Kingston PL 12,179.2 83.8 0.0 Tisbury DU 4,825.6 53.6 0.0 Seekonk BR 11,955.2 52.8 0.0 Rockport ES 4,531.2 48.2 0.0 Danvers ES 8,857.6 34.9 0.0 Nahant ES 678.4 32.8 0.0 Salem ES 5,235.2 30.8 0.0 Acushnet BR 12,038.4 30.4 0.0 Beverly ES 9,830.4 29.5 0.0 Gay Head DU 4,057.6 29.0 6.6 West Tisbury DU 17,075.2 20.9 0.0 Manchester ES 4,940.8 19.1 0.0 Lynn ES 7,174.4 17.6 0.0 Hanover PL 10,003.2 16.2 0.0 Peabody ES 10,758.4 9.0 0.0 Ames bury ES 8,838.4 8.0 0.0 Braintree NO 9,222.4 6.0 0.0 Marblehead ES 2,828.8 6.0 0.0 Fall River BR 24,371.2 3.9 0.0 Chelsea SU 1,388.8 2.0 0.0 Everett MI 2,400.0 0.0 0.0 New Bedford BR 12,691.2 0.0 0.0 Swamps CO tt ES 1,984.0 0.0 0.0 State Totals 1, 079,981.0 48,104.6 54.5 All areas given in acres - 10 Table 4 1-1 1—1 0) c c s c o o o C3 1 o a cfl cfl S S o- LTl csir^oorocoo— io>m ^HC^OF — r-^*^i— If— I *> Wf ¥y ^ r » #v vo ro ^j o> ^H 00 — I (0 V •H o IN oooinoooLoo vOOOOCsliriKlvDm cNmiriav o CM in 1^ O •H U OB bO CO 0) u (0 «0 w M-l O a o (0 •H (d o o c/0 ^ c .H z*"^ r^ in CO CO O O in CM o m ^H o «K ri #\ ^ r> in CO 1—1 00 1— I r-. o H (U 4-1 cfl iH X 4J J3 .'^-l cfl M 3 CO •H cfl O rH 3 PQpaQDqgZSCLiC/i CU o 0) M 0) m - 11 - TIDAL FLATS Introduction Tidal flats, as defined by the coastal regulations to the Massachusetts Wetlands Protection Act, are those nearly level parts of coastal beaches which usually extend from the mean low water line landward to the more steeply sloping face of the beach, or which may be separated from the beach by an area of deeper water. They are exposed at low tide and may or may not be connected to the rest of a coastal beach. Tidal flats are commonly found both along shorelines exposed to the open ocean or within estuaries and the material making up the flat will generally reflect these differences in location; finer sediments are generally more common on protected flats and larger, sandy material more common in exposed areas. The values of tidal flats are often underestimated in the public eye. Most people recognize them as habitat for shellfish, however, they also play an important role in lessening storm waves and providing sediment to down-current beaches. The critical relationships with saltmarshes in the flow of nutrients within the estaurine or marine ecosystem are presently becoming better understood (6) . For further information on the nature and values of tidal flats, the reader is referred to The Ecology of New England Tidal Flats: a com- munity profile (7) . Study Methodology The methodology to determine tidal flat locations and areas was the same as that described above for salt marshes. Both estuarine and marine tidal flats (E2FL and M2FL respectively in the NWI indicator codes) were identified and planime- tered on black line copies of the National Wetlands Inventory maps. Again, one half acre was the minimum threshold for resource area size used in developing the NWI maps. To our knowledge, this is the first systematic survey of tidal flats within the Commonwealth. Table 5 lists acreages by town within counties. Table 6 provides the acreage of tidal flats by community in descending, sequential order. In each case, totals are provided for both marine (open ocean) and estuarine (within bays, river mouths, salt ponds, etc.) flats and combined as tidal flats. Discussion The north side of Cape Cod (Barnstable County) has extensive marine flats as may be seen in the figures of Eastham, Brewster, Wellfleet and Yarmouth. Estuarine flats are concentrated in such areas as Duxbury Bay, Pleasant Bay (Chatham and Orleans), Barnstable Harbor, Plymouth Bay, and the Westport River. 12 - Table 5 TIDAL FLAT ACREAGE WITHIN COUNTIES Town Town Area Tidal Flat Marine Estuarine in Acres acreage in Flat Flat Town Acreage Acreage Barnstable County Eastham 9,344.0 2,817.9 2,275.4 542.5 Barnstable 40,153.6 2,646.4 689.2 1,957.2 Orleans 9,081.6 2,441.1 413.5 2,027.6 Brewster 16,102.4 2,367.2 2,352.3 14.9 Chatham 10,438.4 2,231.9 1,098.0 1,133.9 Wellfleet 13,324.8 1,893.7 1,107.2 786.5 Yarmouth 16,339.2 1,542.1 1,065.3 476.8 Dennis 14,016.0 1,002.1 880.1 122.0 Falmouth 29,260.8 307.5 127.3 180.2 Province town 5,600.0 205.4 43.0 162.4 Bourne 26,585.6 201.8 35.8 166.0 Truro 13,824.0 92.5 0.0 92.5 Mashpee 16,614.4 51.6 0.0 51.6 Sandwich 27,916.8 7.4 0.0 7.4 Harwich 14,342.4 0.0 0.0 0.0 Totals 262,944.0 17,808.6 10,087.1 7,721.5 Bristol County Westport 35,353.6 2,032.8 0.0 2,032.8 Fairhaven 7,936.0 582.1 442.0 140.1 Dartmouth 39,558.4 281.7 14.7 267.0 New Bedford 12,691.2 107.7 0.0 107.7 Berkley 10,496.0 53.6 0.0 53.6 Acushnet 12,038.4 49.8 0.0 49.8 Swansea 14,585.6 11.4 0.0 11.4 Dighton 14,304.0 7.0 0.0 7.0 Somerset 5,446.4 4,4 0.0 4.4 Fall River 24,371.2 0.0 0.0 0.0 Freetown 23,174.4 0.0 0.0 0.0 Re hobo th 30,374.4 0.0 0.0 0.0 Seekonk 11,955.2 0.0 0.0 0.0 Totals 242,284.8 3,130.5 456.7 2,673.8 Dukes County Edgartown 18,720.0 786.9 154.1 632.8 Tisbury 4,825.6 221.1 0.0 221.1 Chilmark 14,182.4 119.5 6.0 113.5 Gay Head 4,057.6 47.8 0.0 47.8 Oak Bluffs 4,640.0 37.9 0.0 37.9 Gosnold 8,288.0 34.1 25.4 8.7 West Tisbury 17,075.2 11.4 0.0 11.4 Totals 71,788.8 1,258.7 185.5 1,073.2 - 13 - Essex County Ipswich 21,344.0 Gloucester 16,928.0 Newburyport 5,702.4 Essex 9,203.4 Newbury 15,577.6 Salem 5,235.2 Beverly 9,830.4 Rowley 12,179.2 Manchester 4,940.8 Salisbury 10,323.2 Marblehead 2,828.8 Danvers 8,857.6 Saugus 7,411.2 Rockport 4,531.2 Lynn 7,174.4 Amesbury 8,838.4 Nahant 678.4 Peabody 10,758.4 Swampscott 1,984.0 1,539.9 516.8 1,023.1 1,412.9 510.0 902.9 690.7 0.0 690.7 512.5 0.0 512.5 431.6 127.7 303.9 317.0 196.0 121.0 303.9 198.5 105.4 211.2 12.6 198.6 127.6 111.4 16.2 115.5 115.5 0.0 112.2 112.2 0.0 96.5 0.0 96.5 92.2 0.0 92.2 74.7 74.7 0.0 49.3 0.0 49.3 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Totals 164,326.6 6,087.7 1,975.4 4,112.3 Middlesex County Everett 2,400.0 0.0 0.0 0.0 Nantucket County Nantucket 32,217.6 136.9 0.0 136.9 Norfolk County Quincy 10,649.6 Weymouth 11,340.8 Cohasset 6,438.4 Braintree 9,222.4 Milton 8,448.0 1,459, .6 549, .7 287, .6 37, .7 0, .0 0.0 1,459.6 0.0 549.7 0.0 287.6 0.0 37.7 0.0 0.0 Totals 46,099.2 2,334.6 0.0 2,334.6 Plymouth County Duxbury 15,686.4 Plymouth 66,048.0 Kingston 12,179.2 Scituate 10,924.8 Hingham 14,457.6 Hull 1,619.2 Mattapoiset 11,187.2 Wareham 24,339.2 Marshfield 18,252.8 Marion 9,152.0 Hanover 10,003.2 Norwell 13,651.2 Pembroke 14,886.4 3,436.8 0.0 3,436.8 2,109.5 20.3 2,089.2 905.0 0.0 905.0 621.8 0.0 621.8 614.5 0.0 614.5 511.0 0.0 511.0 453.6 439.5 14.1 451.2 256.3 194.9 172.9 0.0 172.9 93.6 46.7 46.9 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Totals 222,387.2 9,369.9 762.8 8,607.1 Suffolk County Boston 29,056.0 Winthrop 1,043.2 Revere 4,044.8 Chelsea 1,388.8 Totals 35,532.8 1,387.3 129.1 1,258.2 878.5 0.0 295.8 0.0 183.5 129.1 29.5 0.0 878, .5 295, .8 54, .4 29. .5 TIDAL FLAT ACREAGE BY TOWN - 14 - Table 6 (arranged in descending order) Town County Town Area Tidal Flats Marine Estuarine Flats 0.0 Flats Duxbury PL 15,686.4 3; ,436.8 3 ,436.8 Eastham BA 9,344.0 1, ,817.9 2,275.4 542.5 Barnstable BA 40,153.6 1. ,646.4 689.2 1 ,957.2 Orleans BA 9,081.6 2 ,441.1 413.5 2 ,027.6 Brewster BA 16,102.4 2 ,367.2 2,352.3 14.9 Chatham BA 10,438.4 2 ,231.9 1,098.0 1 ,133.9 Plymouth PL 66,048.0 2 ,109.5 20.3 2 ,089.2 Westport BR 35,353.6 2 ,032.8 0.0 2 ,032.8 Wellfleet BA 13,324.8 1 ,893.7 1,107.2 786.5 Yarmouth BA 16,339.2 1 ,542.1 1,065.3 476.8 Ipswich ES 21,344.0 1 ,539.9 516.8 1 ,023.1 Quincy NO 10,649.6 1 ,459.6 0.0 1 ,459.6 Gloucester ES 16,928.0 1 ,412.9 510.0 902.9 Dennis BA 14,016.0 1 ,002.1 880.1 122.0 Kingston PL 12,179.2 905.0 0.0 905.0 Boston SU 29,056.0 878.5 0.0 878.5 Edgartown DU 18,720.0 786.9 154.1 632.8 Newburyport ES 5,702.4 690.7 0.0 690.7 Scituate PL 10,924.8 621.8 0.0 621.8 Hingham PL 14,457.6 614.5 0.0 614.5 Fairhaven BR 7,936.0 582.1 442.0 140.1 Weymouth NO 11,340.8 549.7 0.0 549.7 Essex ES 9,203.4 512.5 0.0 512.5 Hull PL 1,619.2 511.0 0.0 511.0 Mattapoiset PL 11,187.2 453.6 439.5 14.1 Wareham PL 24,339.2 451.2 256.3 194.9 Newbury ES 15,577.6 431.6 127.7 303.9 Salem ES 5,235.2 317.0 196.0 121.0 Falmouth BA 29,260.8 307.5 127.3 180.2 Beverly ES 9,830.4 303.9 198.5 105.4 Winthrop SU 1,043.2 295.8 0.0 295.8 Cohasset NO 6,438.4 287.6 0.0 287.6 Dartmouth BR 39,558.4 281.7 14.7 267.0 Tisbury DU 4,825.6 221.1 0.0 221.1 Rowley ES 12,179.2 211.2 12.6 198.6 Provincetown BA 5,600.0 205.4 43.0 162.4 Bourne BA 26,585.6 201.8 35.8 166.0 Revere SU 4,044.8 183.5 129.1 54.4 Marshfield PL 18,252.8 172.9 0.0 172.9 Nantucket NA 32,217.6 136.9 0.0 136.9 All areas given in acres 15 - TIDAL FLAT ACREAGE BY TOWN (continued) Town County Town Area Tidal Flats Marine Flats 111.4 Estuarine Flats Manchester ES 4,940.8 127.6 16.2 Chilmark DU 14,182.4 119.5 6.0 113.5 Salisbury ES 10,323.2 115.5 115.5 0.0 Marblehead ES 2,828.8 112.2 112.2 0.0 New Bedford BR 12,691.2 107.7 0.0 107.7 Danvers ES 8,857.6 96.5 0.0 96.5 Marion PL 9,152.0 93.6 46.7 46.9 Truro BA 13,824.0 92.5 0.0 92.5 Saugus ES 7,411.2 92.2 0.0 92.2 Rockport ES 4,531.2 74,7 74.7 0.0 Berkley BR 10,496.0 53.6 0.0 53.6 Mashpee BA 16,614.4 51.6 0.0 51.6 Acushnet BR 12,038.4 49.8 0.0 49.8 Lynn ES 7,174.4 49.3 0.0 49.3 Gay Head DU 4,057.6 47.8 0.0 47.8 Oak Bluffs DU 4,640.0 37.9 0.0 37.9 Braintree NO 9,222.4 37.7 0.0 37.7 Go s no Id DU 8,288.0 34.1 25.4 8.7 Chelsea SU 1,388.8 29.5 0.0 29.5 Swansea BR 14,585.6 11.4 0.0 11.4 West Tisbury DU 17,075.2 11.4 0.0 11.4 Sandwich BA 27,916.8 7.4 0.0 7.4 Dighton BR 14,304.0 7.0 0.0 7.0 Somerset BR 5,446.4 4.4 0.0 4.4 Amesbury ES 8,838.4 0.0 0.0 0.0 Everett MI 2,400.0 0.0 0.0 0.0 Fall River BR 24,371.2 0.0 0.0 0.0 Freetown BR 23,174.4 0.0 0.0 0.0 Hanover PL 10,003.2 0.0 0.0 0.0 Harwich BA 14,342.4 0.0 0.0 0.0 Milton NO 8,448.0 0.0 0.0 0.0 Nahant ES 678.4 0.0 0.0 0.0 Norwell PL 13,651.2 0.0 0.0 0.0 Peabody ES 10,758.4 0.0 0.0 0.0 Pembroke PL 14,886.4 0.0 0.0 0.0 Rehoboth BR 30,374.4 0.0 0.0 0.0 Seekonk BR 11,955.2 0.0 0.0 0.0 Swamps CO tt ES 1,984.0 0.0 0.0 0.0 State Totals 1,079,981.0 41,514.2 13,596.6 27,917.6 All areas given in acres - 16 - BARRIER BEACHES Introduction Barrier beaches are geologic landforms defined in the regulations to the Massachusetts Wetlands Protection Act as narrow, low-lying strips of land generally consisting of coastal beaches and coastal dunes extending roughly parallel to the trend of the coast. They are separated from the mainland by a relatively narrow body of fresh, brackish, or saline water or by a salt marsh system. A barrier beach may be joined to the mainland at one or both ends. Storm damage prevention and flood control are two of the most obvious values of these resource areas. The sands of a barrier beach can absorb the force of storm waves, and the reshaping of beaches and dunes by waves provides material to beaches down-current and eases the effects of erosion. Barrier beaches are also often important recreational areas and provide nesting and resting sites for many species of shore and migratory birds. For further information about barrier beaches, their resources and management, see the Barrier Beach Management Sourcebook (8) and Massachusetts Barrier Beaches (9) . Study Methodology The acreage of barrier beach units was developed from an inventory prepared for the Massachusetts Coastal Zone Management (MCZM) program by the Provincetown Center for Coastal Studies. Delineation of barrier units was made on US Geological Survey 71/2 minute quadrangle topographic sheets. Original versions of these maps are on file in the MCZM office. Reduced size versions as well as identification criteria and study methodology information are available in Massachusetts Barrier Beaches (9) or through MCZM. As with the salt marshes and tidal flats described above, each defined area was traced using the Numonics digital read-out planimeter at the US Fish and Wildlife Service' Region V office. Numbers of barrier units and their acreage were recorded by town and county. County and state acreages are presented in Table 1. Numbers of barriers and acreages listed by town within county sequence are found in Table 7. Table 8 lists barrier beach acreage by town. Discussion A size distribution of the Commonwealth's barriers was prepared and is presented in Table 9. For the purposes of this analysis, the acreage of the entire geolo- gic landform was used, despite any political boundaries. The barrier beach inventory is based on community units and a large barrier such as Plum Island may have its acreage divided among several towns. The distribution analysis indicates that most of the 661 barriers of Massachusetts are relatively small. - 17 - More than half are less than 2.5 acres and more than three-quarters are less than 10 acres. Conversely, the 30 largest barriers make up three-quarters of the total barrier beach acreage in the state. These 30 barrier landforms are listed in Table 10. Interestingly, the Town of Gosnold (the Elizabeth Islands) has the largest number of barriers, and, in fact, has more barrier beaches (7 7) than year-round residents (63) according to the 1980 census. - 18 - Table 7 NUMBERS OF BARRIER BEACH SEGMENTS AND ACREAGE WITHIN COUNTIES Town Town Area Barrier Beach Barrier Beach in Acres Acreage in Segments in Town Town Barnstable County Falmouth 29,260.8 278.4 44 Barnstable 40,153.6 1,700.7 29 Bourne 26,585.6 75.0 29 Wellfleet 13,324.8 164.4 22 Chatham 10,438.4 3,108.1 20 Orleans 9,081.6 532.1 17 Yarmouth 16,339.2 212.5 13 Dennis 14,016.0 232.2 12 Eastham 9,344.0 224.7 7 Harwich 14,342.4 27.1 7 Truro 13,824.0 1,001.1 7 Mashpee 16,614.4 128.5 6 Sandwich 27,916.8 259.5 5 Brewster 16,102.4 53.0 4 Province town 5,600.0 725.8 2 Totals 262,944.0 8,723.1 224 Bristol County Fairhaven 7,936.0 86.3 23 Dartmouth 39,558.4 154.4 13 Westport 35,353.6 729.4 6 Swansea 14,585.6 33.5 2 Somerset 5,446.4 4.5 1 Acushnet 12,038.4 0.0 0 Berkley 10,496.0 0.0 0 Dighton 14,304.0 0.0 0 Fall River 24,371.2 0.0 0 Freetown 23,174.4 0.0 0 New Bedford 12,691.2 0.0 0 Rehoboth 30,374.4 0.0 0 Seekonk 11,955.2 0.0 0 Totals 242,284.8 1,008.1 45 Dukes County Gosnold 8,288.0 186.3 77 Edgartown 18,720.0 962.6 40 Chilmark 14,182.4 297.0 19 West Tisbury 17,075.2 82.5 17 Oak Bluffs 4,640.0 115.4 13 Tisbury 4,825.6 88.1 13 Gay Head 4,057.6 403.8 3 Totals 71,788.8 2,135.7 182 - 19 - Essex County Gloucester 16,928.0 171.6 9 Ipswich 21,344.0 1,333.3 6 Rockport 4,531.2 35.6 5 Manchester 4,940.8 10.7 4 Nahant 678.4 80.0 3 Beverly 9,830.4 1.5 Marblehead 2,828.8 14.6 Newbury 15,577.6 606.6 Newburyport 5,702.4 166.1 Rowley 12,179.2 186.0 Salisbury 10,323.2 345.3 Swampscott 1,984.0 4.1 Amesbury 8,838.4 0.0 0 Danvers 8,857.6 0.0 0 Essex 9,203.4 0.0 0 Lynn 7,174.4 0.0 0 Peabody 10,758.4 0.0 0 Salem 5,235.2 0.0 0 Saugus 7,411.2 0.0 0 Totals 164,326.6 2,955.4 34 Middlesex County Everett 2,400.0 0.0 0 Nantucket County Nantucket 32,217.6 1,841.7 56 Norfolk County Quincy 10,649.6 71.4 6 Cohasset 6,438.4 20.1 3 Weymouth 11,340.8 4.2 1 Braintree 9,222.4 0.0 0 Milton 8,448.0 0.0 0 Totals 46,099.2 95.7 10 Plymouth County Wareham 24,339.2 58.7 36 Mattapoiset 11,187.2 83.5 26 Marion 9,152.0 36.9 14 Plymouth 66,048.0 348.0 12 Scituate 10,924.8 323.1 11 Hull 1,619.2 599.0 9 Marshf ield 18,252.8 232.1 6 Hingham 14,457.6 4.8 3 Duxbury 15,686.4 247.7 1 Hanover 10,003.2 0.0 0 Kingston 12,179.2 0.0 0 Norwell 13,651.2 0.0 0 Pembroke 14,886.4 0.0 0 Totals 222,387.2 1,933.8 118 Suffolk County Boston 29,056.0 28.4 11 Revere 4,044.8 151.2 2 Winthrop 1,043.2 14.9 2 Chelsea 1,388.8 0.0 194.5 0 Totals 35,532.8 15 - 20 - Table 8 BARRIER BEACH ACREAGE BY TOWN (arranged in descending order) Town County Town Area Barrier Beach Number of in acres Acreage within Town barriers in Town Chatham BA 10,438.4 3,108.1 20 Nantucket NA 32,217.6 1,841.7 56 Barnstable BA 40,153.6 1,700.7 29 Ipswich ES 21,344.0 1,333.3 6 Truro BA 13,824.0 1,001.1 7 Ed gar town DU 18,720.0 962.6 40 Westport BR 35,353.6 729.4 6 Provincetown BA 5,600.0 725.8 2 Newbury ES 15,577.6 606.6 1 Hull PL 1,619.2 599.0 9 Orleans BA 9,081.6 532.1 17 Gay Head DU 4,057.6 403.8 3 Plymouth PL 66,048.0 348.0 12 Salisbury ES 10,323.2 345.3 1 Scituate PL 10,924.8 323.1 11 Chilmark DU 14,182.4 297.0 19 Falmouth BA 29,260.8 278.4 44 Sandwich BA 27,916.8 259.5 5 Duxbury PL 15,686.4 247.7 1 Dennis BA 14,016.0 232.2 12 Marshfield PL 18,252.8 232.1 6 Eastham BA 9,344.0 224.7 7 Yarmouth BA 16,339.2 212.5 13 Gosnold DU 8,288.0 186.3 77 Rowley ES 12,179.2 186.0 1 Gloucester ES 16,928.0 171.6 9 Newburyport ES 5,702.4 166.1 1 Wellfleet BA 13,324.8 164.4 22 Dartmouth BR 39,558.4 154.4 13 Revere SU 4,044.8 151.2 2 Mashpee BA 16,614.4 128.5 6 Oak Bluffs DU 4,640.0 115.4 13 Tisbury DU 4,825.6 88.1 13 Fairhaven BR 7,936.0 86.3 23 Mattapoiset PL 11,187.2 83.5 26 West Tisbury DU 17,075.2 82.5 17 Nahant ES 678.4 80.0 3 Bourne BA 26,585.6 75.0 29 Quincy NO 10,649.6 71.4 6 Wareham PL 24,339.2 58.7 36 - 21 - BARRIER BF.ACH ACREAGE BY TOWN (continued) Town County Town Area Barrier Beach Number of in acres Acreage within Town barriers in Town Brewster BA 16,102.4 53.0 4 Marion PL 9,152.0 36.9 14 Rockport ES 4,531.2 35.6 5 Swansea BR 14,585.6 33.5 2 Boston SU 29,056.0 28.4 11 Harwich BA 14,342.4 27.1 7 Cohasset NO 6,438.4 20.1 3 Winthrop SU 1,043.2 14.9 2 Marblehead ES 2,828.8 14.6 1 Manchester ES 4,940.8 10.7 4 Hingham PL 14,457.6 4.8 3 Somerset BR 5,446.4 4.5 1 Weymouth NO 11,340.8 4.2 1 Swamps cot t ES 1,984.0 4.1 1 Beverly ES 9,830.4 1.5 1 Acushnet BR 12,038.4 0.0 0 Ames bury ES 8,838.4 0.0 0 Berkley BR 10,496.0 0.0 0 Braintree NO 9,222.4 0.0 0 Chelsea SU 1,388.8 0.0 0 Dan vers ES 8,857.6 0.0 0 Dighton BR 14,304.0 0.0 0 Essex ES 9,203.4 0.0 0 Everett MI 2,400.0 0.0 0 Fall River BR 24,371.2 0.0 0 Freetown BR 23,174.4 0.0 0 Hanover PL 10,003.2 0.0 0 Kingston PL 12,179.2 0.0 0 Lynn ES 7,174.4 0.0 0 Milton NO 8,448.0 0.0 0 New Bedford BR 12,691.2 0.0 0 Norwell PL 13,651.2 0.0 0 Peabody ES 10,758.4 0.0 0 Pembroke PL 14,886.4 0.0 0 Rehoboth BR 30,374.4 0.0 0 Salem ES 5,235.2 o.n 0 Saugus ES 7,411.2 0.0 0 Seekonk BR 11,955.2 0,0 0 state Totals 1,079,981.0 18,888.0 684 Table 9 SIZE DISTRIBUTION OF MASSACHUSETTS BARRIER BEACHES Range of Acreage // vjich in ranj; ;e & Cumulative : total & % of Tot :al % of Total 0 _ .4 47 7 % .5 - .9 94 14 % 141 21 % 1.0 - 1.4 88 13 % 229 35 % 1.5 - 1.9 59 9 % 288 44 % 2.0 - 2.9 69 10 % 357 54 % 3.0 - 4.9 70 11 % 427 65 % 5.0 - 9.9 87 13 % 514 78 % 10.0 - 49.9 99 15 % 613 93 % 50.0 - 99.9 18 3 % 631 95 % 100.0 - 999.9 25 4 % 656 99 % over 1000 5 less than 1 % 661 100 % The 5 largest barriers ( 1 % of total) make up 38 % of total acres. The 30 largest barriers ( 5 % of total) make up 75 % of total acres. All areas given In acres, - 23 - Table 10 THE 30 LARGEST BARRIER BEACH LANDFORMS IN MASSACHUSETTS Acreage Barrier Name 2126.8 1381.7 1255.0 1241.4 Monomoy Island Sandy Neck Nauset Beach Plum Island Town(s) 1119.6 Coatue Point and Beach Chatham Barnstable, Sandwich Chatham, Orleans Ipswich, Newbury, Newburyport, Rowley Nantucket County Barnstable Barnstable Barnstable Essex Nantucket 875.2 Castle Neck/Cranes Beach Ipswich, Gloucester Essex 789.0 Head of the Meadow Beach Truro Barnstable 651.7 Horseneck Beach Westport Bristol 527.7 Nantasket Beach Hull Plymouth 442.7 Race Point/Hatches Harbor Provincetown Barnstable 345.3 Salisbury Beach Salisbury Essex 337.5 Lobsterville/West Payson Road Gay Head Dukes 310.8 Duxbury Beach Duxbury, Marshfield, Plymouth Plymouth 301.2 Cape Poge Edgartown Dukes 283.1 Wood End/Long Point Provincetown Barnstable 270.6 Hummarock/ Rexhame Marshfield, Scituate Plymouth 223.5 Norton Point Edgartown Dukes 149.7 Revere Beach Revere Suffolk 138.7 Wauwinet Nantucket Nantucket 135.7 Coast Guard/Nauset Beach Eastham Barnstable 134.6 Great Island Yarmouth Barnstable 133.5 Chapin Beach Dennis Barnstable 132.2 Beach Point Truro Barnstable 129.3 Edgartown Great Pond Edgartown Dukes 127.0 Squibnocket/Long Beach Chilmark, Gay Head Dukes 124.1 Plymouth Beach Plymouth Plymouth 122.2 East Sandwich/Springhill Sandwich Barnstable 121.2 Eel Point Nantucket Nantucket 116.4 Dead Neck Barnstable Barnstable 103.3 Ester Island Nantucket Nantucket - 24 REFERENCES (1) Nixon, Scott W. 1982 The Ecology of New England High Salt Marshes: A community profile , US Fish and Wildlife Service, Office of Biological Services, Washington, D.C. FWS/OBS - 81/55 70 pp. (2) Cowardin, L.M., V. Carter, F.C. Golet, and E.T. LaRoe 1979 Classification of Wetlands and Deepwater Habitats of the United States. US Fish and Wildlife Service, Office of Biological Services, Washington, D.C. FWS/OBS - 79/31 103 pp. (3) MacConnell, William P. 1975 Remote Sensing 20 Years of Change in Massachusetts, 1951/52- T971/72. Massachusetts Agricultural Experiment Station, University of Massachusetts, Amherst, MA. Research Bulletin #630 79 pp. (4) US Fish and Wildlife Service 1954 Wetlands Inventory of Massachusetts Office of River Basin Studies, US Fish and Wildlife Service, Boston, MA. 28 pp. (5) US Fish and Wildlife Service 1965 Supplementary Report (June 1965) on the Coastal Wetlands Inventory of Massachusetts. US Fish and Wildlife Service, Bureau of Sport Fisheries and Wildlife, Region V, Boston, MA. 13 pp. (6) Welsh, Barbara L. 1980 Comparitive Nutrient Dynamics of a Marsh-Mudf lat Ecosystem. Estuarine and Coastal Marine Sciences (1980), 10, 143-164. - 25 (7) Whitlatch, Robert B. 1982 The Ecology of New England Tidal Flats: A coramunity profile. US Fish and Wildlife Service, Office of Biological Services, Washington, DC, FWS/OBS - 81/01 125 pp. (8) Smith, Lester B., Jr. 1983 Barrier Beach Management Sourcebook. Massachusetts Coastal Zone Management Program, Boston, MA. 48 pp, (9) Massachusetts Coastal Zone Management Program 1979 Massachusetts Barrier Beaches . Massachusetts Coastal Zone Management Program, Boston, MA. 80 pp. - 26 APPENDIX Classification Scheme for Salt Marshes and Tidal Fl at s The classification scheme used on the National Wetlands Inventory maps is that provided in Classification of Wetlands and Deepwater Habitats of the United States (2) , This is based on a hierarchical model of System/ Sub-system Class / Sub-Class based on ecosystem and abiotic factors: Systems: include Estuarine and Marine (the two important to this study) as well as Palustrine, Lacustrine, and Riverine. Subsystems: where applicable, Intertidal (both salt marshes and tidal flats are found here) and Subtidal. - Class: flat, emergent, scrub/shrub (the classes important here), rocky shore, beach bar, etc. - Subclass: includes type of vegetation, water regimes and the like. (Subclasses were not used in this analysis.) For the resources included in this work, the inter-relationships between the various systems, classes, and subsets of each are schematically illustrated below. System Subsystem Class Marine Intertidal Flat Estuarine Intertidal Flat Emergent Vegetation (salt marsh) Scrub/Shrub (shrub marsh) An Estuarine System consists of deepwater tidal habitats and adjacent tidal wetlands that are semienclosed by land but have open, partly obstructed, or sporadic access to the open ocean, and in which ocean water is diluted by fresh water runoff from the landward side. The Estuarine System extends upstream and landward to the point that ocean-derived salinity measures less than 0.5 o/oo (parts per thousand) during the period of average low flow. The seaward boun- dary is an imaginary line closing the mouth of the river, bay, or sound, or the seaward limit of emergent vegetation, whichever is greater. The Marine System consists of the open ocean and its associated high-energy coastline. Marine habitats are exposed to the waves and currents of the open ocean. Salinities generally exceed 30 o/oo with little or no dilution except directly outside mouths of estuaries. Emergent vegetation is characterized by erect, rooted, herbaceous, aquatic or - 11 - water tolerant plants. This vegetation is present for most of the growing season in most years. Emergent wetlands are relative stable and retain the same appearance year after year. Included within each polygon on the National Wetlands Inventory maps is an encoded classification of wetland type. These take the following form: Example 1 Salt Marsh E2EM E 2 EM Example 2. Shrub Marsh E2SS E 2 SS Example 3. Estuarine Flat E2FL E Estuarine System Intertidal Subsystem Emergent vegetation (Class) Estuarine Intertidal Subsystem Scrub/Shrub (Class) - Estuarine System 2 - Intertidal Subsystem FL - Flat (Class) Example 4. Marine Flat M2FL M - Marine System 2 - Intertidal Subsystem FL - Flat (Class) Each polygon containing these codes was identified and measured to develop the acreage figures shown In the text. Estuarine and Marine Flats were also com- bined to be listed as Tidal Flats. Preperty Of Library