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Report: Impacts of Sand Removal from and Placement in Coastal Barrier

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Report: Impacts of Sand Removal from and Placement in Coastal Barrier U.S. Fish & Wildlife Service U.S. Geological Survey and U.S. Fish & Wildlife Service Report: Impacts of Sediment Removal from and Placement in Coastal Barrier Island Systems Frequently Asked Questions Q: Who prepared this report and why was it created? On June 2, 2021, the U.S. Geological Survey (USGS) published an Open File Report on the impacts of sediment removal from and placement in coastal barrier island systems (OFR 2021-1062). The report was prepared jointly by the USGS and the U.S. Fish and Wildlife Service (FWS) in response to a June 2019 request from the House Committee on Natural Resources that the two agencies evaluate the short- and long-term impacts of sediment removal on areas in and adjacent to the Coastal Barrier Resources System (CBRS). The agencies assembled a team of scientists and landscape Army Corps of Engineers managers who reviewed and U.S. summarized the scientific literature on The U.S. Army Corps of Engineers Philadelphia District pumps sand onto Brant how sediment-supply alterations affect Beach, NJ in June of 2013 physical and ecological processes of coastal barriers and, in turn, how actions for any particular CBRS units tion about CBRA is available at: https:// specific species, habitats, and coastal or other site-specifc areas were be- www.fws.gov/cbra. resilience are impacted. The report can yond the scope of this report. be accessed at: https://doi.org/10.3133/ Q: What are coastal barrier island ofr20211062. Q: What is the Coastal Barrier Resourc- systems? es Act? Barrier islands, and the environments Q: What is the scope of the report? The Coastal Barrier Resources Act therein, are dynamic systems, re- This report contains a comprehensive (CBRA) of 1982 originally established sponding to wave and tidal processes, summary of the scientific literature on the CBRS which now encompasses sediment supply and disruption, and the physical, biological, and ecological about 3.5 million acres along the Atlan- sea-level change. These islands sup- effects of sediment removal and place- tic, Gulf of Mexico, Great Lakes, U.S. port a great diversity of plants and ment in coastal barrier island systems. Virgin Islands, and Puerto Rico coasts. animals, including many threatened Specifically, the report presents the The purpose of the law is to protect and endangered species. Historically, consensus findings and relevant knowl- natural resources, save taxpayer mon- coastal barrier island systems were edge gaps associated with the impacts ey, and keep people out of harm’s way largely sustained by natural sediment of sediment removal and placement on: by removing the federal incentive to de- exchanges between the inner conti- physical barrier island processes and velop ecologically-sensitive and storm- nental shelf, shoreface, beach, dunes, sediment supplies; benthic habitats; fish prone coastal barriers. CBRA prohibits marsh, and estuary. Today, humans also and other marine species; subaerial most new federal expenditures and alter these systems through sediment beach habitats; and coastal resiliency. fnancial assistance for projects and management, which refers to the re- activities within the CBRS, including moval of sediment from one part of the The report identifies the physical and projects to prevent the erosion of, or to system (e.g., dredging) for placement in biological data required for assessing otherwise stabilize, any inlet, shoreline, another part of the system (e.g., nour- and monitoring impacts of sediment or inshore area (16 U.S.C. 3504(a)(3)). ishment). These practices are used for management actions in coastal barrier The law does not restrict the use of either hazard mitigation (e.g., erosion island systems and provides a table of private, state, or local funds or limit the and food control) or coastal resto- existing USGS data resources for five issuance of federal permits within the ration (e.g., expansion or restoration CBRS areas of interest as identified by CBRS. FWS is responsible for main- of beach, dune, and/or marsh habitats). FWS (Hereford Inlet, NJ, Carolina taining the maps that depict the CBRS In instances where barrier systems are Beach, NC, Masonboro Inlet, NC, New and consulting with other federal altered through human intervention, River Inlet, NC, and Folly Beach, SC). agencies that propose spending funds naturally occurring coastal processes Assessments of sediment management within the CBRS. Additional informa- can be modifed, enhanced, or impeded. manatees and sea turtles, include direct and back-barrier environments. For Q: What are the key fndings of this entanglement in or physical strikes example, removal of sediment from any report? from dredging equipment. part of the submerged barrier system An extensive review of the literature may alter the position of barrier island for this report found that sediment The report also highlights some posi- shorelines. Over time, placed sediment management actions can have both tive impacts of sediment management. may be dispersed to other barrier is- benefcial and detrimental impacts on For instance, sediment placement can land environments and may cause both coastal species and the physical and increase feeding areas, viable nesting physical and ecological benefts, such as ecological resiliency of barrier island habitat, and increase nesting success increased sediment supply to downdrift systems, depending on where and how for some coastal wildlife like shore- beaches and increasing habitat extent. they are applied. birds and turtles. However, the timing Placement may also result in adverse of nourishment is important, since impacts, such as the alteration of nat- The key fndings in the report illus- the addition of sediments to beaches, ural sediment exchanges between bar- trate how some sediment management dunes and marshes could interfere with rier island environments that decrease practices can have negative impacts on breeding seasons of certain species. habitat suitability. seafoor habitats, fsh and other ma- Though beach nourishment can tem- rine species, beach and dune habitats, porarily protect coastal infrastructure This review revealed a need for more and the coastal sediment supply that and habitats from storm inundation and research and monitoring on the follow- maintains barrier island resiliency. For erosion, it may lead to negative affects ing topics in order to better estimate instance, when sediment is removed at other locations. Beach nourishment both benefcial and adverse physical from one barrier island system and can cause detrimental sedimentation impacts of sediment removal and used in a separate system it reduces on sensitive seafoor habitats and placement on coastal systems: (1) prior the amount of sediment for the orig- the dredging required to acquire the to sediment removal, it is important to inal island. This may lead to coastal sediments needed for nourishment establish the range of natural shoreline erosion near the removal location or can reduce sediment supply to barrier variability so that after sediment re- could cause longer-term impacts to the islands, which reduces their ability to moval, variability in shoreline position supply of sediments to neighboring keep pace with sea-level rise. can be attributed to sediment supply barrier islands, all of which may alter disruptions; (2) substantial uncertainty the islands’ ability to withstand future Five topics addressed in the report and surrounds forecasts of the impacts of storms and increases in sea level. This associated fndings (and knowledge sediment removal or placement due to process of removing sediments from gaps) are: the episodic nature of the storms that an area can also directly and indirectly drive many of the changes and the dif- alter the quality of nearshore seafoor 1. Physical Impacts of Sediment fculty in predicting exact magnitudes habitats like seagrass beds and fsh Removal and Placement on Coastal of storm-related sediment transport; nurseries that are critical for support- Sediment Supplies (3) effects of sediment placement on ing economic and ecologically import- Sediment removal and placement estuarine or back-barrier beaches is ant species. Organisms that live in or reshapes barrier islands and their adja- less studied than effects on ocean-fac- on the seafoor, which often serve as cent environments by altering: a) wave ing beaches; and (4) more food sources for many threatened and and current impacts at the shoreline, understanding is needed of the barrier- endangered coastal and marine spe- b) the volume of sediment exchanged system as a whole, including effects of cies, may be directly excavated during via inlets, c) alongshore sediment sediment removal from inlet-associated dredging activities. Additional impacts transport, and/or d) the frequency of shoals, tidal fats, and channels on inlet to surface-dwelling species, such as sediment exchanges between beaches shore-lines and downdrift sediment supply and physical and ecological feedbacks from sediment placement. 2. Impacts of Sediment Removal and Placement on Benthic Habitats and Their Importance Benthic habitats, and the organisms that live in and on the seabed, are directly and immediately impacted by sediment removal and placement. Changes to water depth, sediment composition, and the hydrodynamic conditions at the seafoor can impact habitat quality for benthic organisms, which are important food resources for shore and waterbirds and other marine species. The physical removal of Army Corps of Engineers sediments causes immediate mortality U.S. and
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