<strong>Coastal</strong> <strong>Resource</strong> <strong>Guide</strong> for <strong>Pleasant</strong> <strong>Bay</strong> <strong>and</strong> <strong>Chatham</strong> HarborSection 7Natural <strong>Resource</strong>s237.1 PurposeThe purposes of this section are <strong>to</strong> briefly describe the region’sglacial his<strong>to</strong>ry <strong>and</strong> sediment regime, <strong>and</strong> <strong>to</strong> illustrate the breadth ofnatural resources in the <strong>Pleasant</strong> <strong>Bay</strong> system, including the currentstatus of water quality in the <strong>Bay</strong>.7.2 MethodologyNarratives describing the <strong>Bay</strong>’s diverse natural resources are basedon previous scientific studies <strong>and</strong> resource management plansfor the <strong>Bay</strong>, as well as information from local <strong>to</strong>wn officials. GISdata depicting wildlife habitats was supplemented by informationfrom Mass Audubon staff familiar with the <strong>Bay</strong>. Water qualityinformation was derived from studies determining critical nitrogenloading thresholds. Robert Oldale’s 2001 publication describing thegeology of Cape Cod <strong>and</strong> the Isl<strong>and</strong>s provided useful informationabout the glacial his<strong>to</strong>ry <strong>and</strong> geology of the bay area.The location <strong>and</strong> distribution of natural resources in the <strong>Bay</strong> is basedon existing maps, Geographic Information System (GIS) data layers(including MORIS <strong>and</strong> ESI data layers), <strong>and</strong> local knowledge.<strong>Coastal</strong> wetl<strong>and</strong> resource areas (e.g., dune, salt marsh, etc.),eelgrass, fish <strong>and</strong> wildlife, <strong>and</strong> priority natural community typesare delineated by MORIS <strong>and</strong> ESI data mapping. MORIS, theMassachusetts Ocean <strong>Resource</strong> Information System, is an onlinemapping <strong>to</strong>ol created by Massachusetts Office of <strong>Coastal</strong> ZoneManagement (CZM) <strong>and</strong> the Massachusetts Office of GeographicInformation (MassGIS). MORIS can be used <strong>to</strong> search <strong>and</strong>display spatial data related <strong>to</strong> the Massachusetts coastal zone(e.g., eelgrass beds, coastal wetl<strong>and</strong>s, shore access points, etc.)on a backdrop of aerial pho<strong>to</strong>graphs. Environmental SensitivityIndex (ESI) maps delineate coastal resources that are at risk,including biological resources, in a geodatabase format. TheMassachusetts Environmental Sensitivity Index Metadata (April2000) provides attribute definition <strong>and</strong> source information.7.3 Surficial GeologyThe type <strong>and</strong> distribution of natural resources in <strong>and</strong> around<strong>Pleasant</strong> <strong>Bay</strong> <strong>and</strong> <strong>Chatham</strong> Harbor are largely influenced bythe area’s Pleis<strong>to</strong>cene glacial his<strong>to</strong>ry <strong>and</strong> the diverse types <strong>and</strong>distribution of sediments deposited during this time. The surficialgeology of Cape Cod, including the <strong>Pleasant</strong> <strong>Bay</strong> area, owes itsorigin <strong>to</strong> the last continental glacier (Laurentide ice sheet) <strong>and</strong>the subsequent rise in sea-level. The dynamics <strong>and</strong> timing ofglaciation as well as the variety of deposits left by the glacier asit advanced <strong>and</strong> retreated over the l<strong>and</strong>scape of Cape Cod isdescribed in detail by Robert Oldale in his book Cape Cod, Martha’sVineyard & Nantucket: The Geologic S<strong>to</strong>ry (Oldale, 2001). Threebroad categories of glacial sediments were deposited during thePleis<strong>to</strong>cene epoch (10,000 years or older) on the Cape: glacialtill, glacial moraine deposits, <strong>and</strong> glacial stratified deposits (S<strong>to</strong>ne& DiGiacomo-Cohen, 2009). Glacial till consists of unsorted <strong>and</strong>unstratified sediments of various grain sizes (boulders, gravel,s<strong>and</strong>, silt, clay) deposited directly on bedrock by the glacier. GlacialSection Highlights<strong>Pleasant</strong> <strong>Bay</strong> supports a wide variety of inl<strong>and</strong> <strong>and</strong>coastal wetl<strong>and</strong> resources, fish <strong>and</strong> wildlife, <strong>and</strong> manyrare species <strong>and</strong> natural community types.<strong>Coastal</strong> <strong>and</strong> inl<strong>and</strong> wetl<strong>and</strong>s serve important publicinterests such as flood control, s<strong>to</strong>rm damageprevention, pollution prevention, <strong>and</strong> marine <strong>and</strong>terrestrial wildlife habitat.Approximately 1,400 acres of salt marsh <strong>and</strong> 225 acresof intertidal flats exist in the <strong>Bay</strong>. Several areas of saltmarsh <strong>and</strong> tidal flat in the <strong>Bay</strong> are identified as “Areasof Critical Marine Habitat” based on their habitat valuesfor coastal waterbirds, horseshoe crabs, <strong>and</strong> the rarediamondback terrapin.Over 1,800 acres of eelgrass beds occur in the <strong>Bay</strong>. Thesehighly productive subtidal communities provide feeding<strong>and</strong> nursery habitat for many marine species, includingmany commercially valuable finfish <strong>and</strong> shellfish species.Seven rare wildlife species have been documented usingbay habitats, including Piping Plover, Northern Harrier,<strong>and</strong> Diamondback terrapin. Many other rare speciesoccur within the study area.Nutrient impacts on <strong>Bay</strong> water quality have beenmoni<strong>to</strong>red since 2000, <strong>and</strong> data were used <strong>to</strong> identifythreshold limits for Total Nitrogen. Reductions in currentwatershed nitrogen load will be needed <strong>to</strong> maintain orres<strong>to</strong>re healthy water quality. Increased flushing fromthe 2007 inlet did not result in changes sufficient <strong>to</strong>mitigate the effects of watershed nitrogen loading.moraine deposits are similarly unsorted <strong>and</strong> unstratified, s<strong>and</strong>ysediments with coarser materials including boulders. Morainedeposits accumulated in ice-walled lakes <strong>and</strong> streams <strong>and</strong> onstagnant, buried ice in front of the receding edge of the ice sheet.Glacial stratified deposits are layered, well-sorted <strong>to</strong> poorlysortedgravel, s<strong>and</strong>, silt <strong>and</strong> clay laid down by flowing meltwaterin glacial streams <strong>and</strong> lakes in front of the retreating ice margin(identified as “coarse” in Map 9). The glacial stratified depositson Cape Cod (e.g., Harwich outwash plain deposits) are the mostextensive in Massachusetts. These broad, gently sloping plainsare sometimes pitted, forming dry depressions or kettle pondswhere the depressions intersect groundwater. Less common areglacial lake sediments composed of gravelly s<strong>and</strong>, silt <strong>and</strong> claythat were deposited in lakes impounded by glacial ice (identifiedas “glaciolacustrine fine” in Map 9). The diverse sedimenttypes deposited by the Laurentide ice sheet comprise the parentmaterials of the Cape’s modern sedimentary environments. Risingsea-levels reworked the glacial sediments forming beaches, dunes<strong>Pleasant</strong> <strong>Bay</strong> Alliance 2011
<strong>Coastal</strong> <strong>Resource</strong> <strong>Guide</strong> for <strong>Pleasant</strong> <strong>Bay</strong> <strong>and</strong> <strong>Chatham</strong> Harbor<strong>and</strong> marshes during the Holocene epoch (post-glacial, less than10,000 years old). Bedrock is not exposed on the Cape due <strong>to</strong> thethick layer of glacial sediments.The distribution <strong>and</strong> types of surficial geologic deposits around<strong>Pleasant</strong> <strong>Bay</strong> is shown on the U.S. Geological Survey’s <strong>Chatham</strong><strong>and</strong> Orleans geologic quadrangle maps (Map 9) (S<strong>to</strong>ne &DiGiacomo-Cohen, 2009). Glacial stratified deposits (“coarse”)comprise almost all of the upl<strong>and</strong>s (not including Nauset Beach)surrounding the <strong>Pleasant</strong> <strong>Bay</strong> <strong>and</strong> <strong>Chatham</strong> Harbor. This map unitconsists of stratified s<strong>and</strong> <strong>and</strong> gravel deposits laid down in variousdepositional environments in front of the retreating ice margin(e.g., meltwater stream, lake deltas, etc.). The sediment layersmay be poorly sorted in gravel deposits <strong>to</strong> well-sorted in s<strong>and</strong> <strong>and</strong>gravel deposits, with faulted bedding due <strong>to</strong> post-depositionalcollapse.Post-glacial deposits in the region surrounding <strong>Pleasant</strong> <strong>Bay</strong> <strong>and</strong><strong>Chatham</strong> Harbor include beaches, dunes, salt marshes, freshwaterswamp <strong>and</strong> marsh deposits, as well as artificial fill. Beaches aretypically linear, narrow deposits of s<strong>and</strong> <strong>and</strong> fine gravel reworkedby waves <strong>and</strong> currents. The texture of beach deposits varies locally<strong>and</strong> is generally controlled by the sediment composition of nearbyglacial materials eroded by wave action. Dunes are wind-depositeds<strong>and</strong>s <strong>and</strong> granules derived from beaches, which may consist ofcross-bedded deposits up <strong>to</strong> 100 feet thick. Nauset Beach <strong>and</strong>North Beach Isl<strong>and</strong> are composed of beaches <strong>and</strong> extensive dunes,with localized areas of s<strong>to</strong>rm beach deposits (e.g., overwash fans,channels) consisting of s<strong>and</strong> <strong>and</strong> gravel deposited by high energys<strong>to</strong>rm waves. Beach <strong>and</strong> dune deposits may also include artificials<strong>and</strong> deposits from locally-replenished beaches. Swamp <strong>and</strong> marshdeposits are composed of decaying marine grasses <strong>and</strong> vegetationwith varying amounts of fine marine sediments. These olderpeat deposits are overlain by live marine <strong>and</strong> brackish wetl<strong>and</strong>vegetation. Swamp <strong>and</strong> marsh deposits occur locally on barrierbeaches where depressions intersect groundwater. Cranberry bogsexist locally in low-lying upl<strong>and</strong> areas. Artificial fill occurs alongthe shoreline (e.g., beneficial re-use of dredged materials on <strong>to</strong>wnbeaches).7.4 <strong>Coastal</strong> Wetl<strong>and</strong> <strong>Resource</strong>sSeveral coastal wetl<strong>and</strong> resource areas, as defined by theMassachusetts Wetl<strong>and</strong>s Protection Act (MWPA) (M.G.L. c. 131,s. 40) <strong>and</strong> its Regulations (310 CMR 10.00), occur in <strong>Pleasant</strong> <strong>Bay</strong>including: Salt Marsh, Barrier Beach, <strong>Coastal</strong> Beach, <strong>Coastal</strong> Dune, 7.4.2 Marine <strong>and</strong> Estuarine Wetl<strong>and</strong>s<strong>Coastal</strong> Bank, <strong>and</strong> other l<strong>and</strong>s subject <strong>to</strong> tidal flow (Map 10 <strong>and</strong> Marine <strong>and</strong> estuarine wetl<strong>and</strong>s include non-vegetated flats (tidalTable 3). The MWPA protects wetl<strong>and</strong>s <strong>and</strong> the public interests flats) <strong>and</strong> vegetated, tidal wetl<strong>and</strong>s. Non-vegetated flats arethey serve, including flood control, prevention of pollution composed of various combinations of s<strong>and</strong>, silt <strong>and</strong> clay (Tiner,<strong>and</strong> s<strong>to</strong>rm damage, <strong>and</strong> protection of public <strong>and</strong> private 2010). Some flats are colonized by algae, while shallow estuarinewater supplies, groundwater supply, fisheries, l<strong>and</strong> containing waters in the <strong>Bay</strong> support extensive beds of eelgrass. Tidal wetl<strong>and</strong>sshellfish, <strong>and</strong> wildlife habitat. For example, <strong>Coastal</strong> Beach is include salt marshes <strong>and</strong> brackish marshes, which are salinitysignificant <strong>to</strong> the interests of s<strong>to</strong>rm damage prevention, flood dependent. Salt marshes develop closest <strong>to</strong> the ocean wherecontrol, <strong>and</strong> the protection of wildlife. Salt Marshes are also salinities are highest, while brackish marshes form along tidal riverssignificant <strong>to</strong> the protection of s<strong>to</strong>rm damage prevention <strong>and</strong> <strong>and</strong> streams where salt water is significantly diluted by fresh water.wildlife habitat, but also <strong>to</strong> the protection of marine fisheries,shellfish, the prevention of pollution, <strong>and</strong> groundwater supply.These public interests are protected by requiring a carefulreview of proposed work that may alter these wetl<strong>and</strong>s. The 24<strong>Pleasant</strong> <strong>Bay</strong> Alliance 2011law protects not only wetl<strong>and</strong>s, but other coastal resourceareas, such as L<strong>and</strong> Subject <strong>to</strong> <strong>Coastal</strong> S<strong>to</strong>rm Flowage (100-yearcoastal floodplain), the Riverfront Area (Rivers Protection Act),<strong>and</strong> L<strong>and</strong> Under Salt Ponds, L<strong>and</strong> Under the Ocean, <strong>and</strong> fishruns. Several tidal or salt ponds exist in the study area, includingRound Cove in Harwich, Crows Pond in <strong>Chatham</strong>, <strong>and</strong> QuansetPond, Arey’s Pond, <strong>and</strong> Kescayogansett (Lonnie’s) Pond in Orleans.Freshwater wetl<strong>and</strong>s <strong>and</strong> water bodies that outflow in<strong>to</strong> <strong>Pleasant</strong><strong>Bay</strong>, as well as isolated wetl<strong>and</strong>s located on coastal l<strong>and</strong>forms(Nauset Beach), also occur within the study area. These includehydrologically-connected lakes <strong>and</strong> ponds <strong>and</strong> their borderingfreshwater wetl<strong>and</strong>s, vernal pools, bogs, shrub swamps, woodedswamps, <strong>and</strong> freshwater seeps. These wetl<strong>and</strong>s are similarlyprotected by the MWPA <strong>and</strong> its regulations under several wetl<strong>and</strong>resource area types: Bordering Vegetated Wetl<strong>and</strong>s, Bank, L<strong>and</strong>Under Water Bodies <strong>and</strong> Waterways, L<strong>and</strong> Subject <strong>to</strong> Flooding, <strong>and</strong>Riverfront Area.Activities within the above wetl<strong>and</strong> resource areas are also strictlyregulated by local <strong>and</strong> federal wetl<strong>and</strong> protection laws <strong>and</strong>regulations. Activities undertaken within 100 feet of wetl<strong>and</strong>slocated within the state-designated ACEC are subject <strong>to</strong> the higherst<strong>and</strong>ard of “no adverse effect.” Local wetl<strong>and</strong> bylaws for <strong>to</strong>wnsbordering the <strong>Bay</strong> may extend wetl<strong>and</strong> protections further thanstate or federal regulations.7.4.1 Beaches, Dunes <strong>and</strong> <strong>Coastal</strong> BanksNauset Beach, the most prominent coastal l<strong>and</strong>form in the <strong>Pleasant</strong><strong>Bay</strong> area, is a barrier beach consisting of coastal beach <strong>and</strong> extensivecoastal dune resource areas. Smaller barrier beaches exist elsewherearound the <strong>Bay</strong>, extending downdrift of headl<strong>and</strong>s (e.g., StrongIsl<strong>and</strong>) <strong>and</strong> protecting small coves <strong>and</strong> marshes. <strong>Coastal</strong> beachesbacked by coastal banks composed of glacial sediments (<strong>and</strong>sometimes associated with small, linear dunes or fringing salt marsh)form much of the shoreline on the western side of the <strong>Bay</strong>. Wherecoastal banks are actively eroding, they provide sediment <strong>to</strong> thecoastal system, allowing beaches, marshes <strong>and</strong> flats <strong>to</strong> accrete <strong>and</strong>keep pace with ongoing sea-level rise. Eroding banks also providenesting sites for some bird species (e.g., bank swallow, beltedkingfisher). Where coastal structures such as seawalls or revetmentsexist, beach <strong>and</strong> dune environments are typically narrower unlessthe shore has been re-nourished.