Proactive Planning for Resilience: Protocols for Community-Led Climate Adaptation in Virginia

Strategy Development

Reducing Risk with Green and Gray Infrastructure

Communities have a choice between green and gray infrastructure to reduce climate change impacts. In the coastal setting, shoreline stabilization is a major concern, and communities can achieve that using gray infrastructure like seawalls, groins and breakwaters, or more natural, “green” infrastructure such as living shorelines, beach replenishment and dune restoration. The benefits and challenges of using green and gray infrastructure are discussed below.

Green Infrastructure

Green infrastructure uses engineered solutions that mimic natural processes to minimize flooding, erosion, and stormwater runoff.1 In the climate resilience context, green infrastructure often takes the form of nature-based solutions. Nature-based solutions are sustainable planning, design, environmental management and engineering practices that weave natural features or processes into the built environment to promote adaptation and resilience to climate change.2 The purpose of these solutions are to reduce damage from a disaster and increase a community’s ability to bounce back. Green infrastructure can be used to reduce flooding and stormwater runoff, fortify coasts against storms, and stabilize shorelines facing sea level rise and erosion.

Green infrastructure protects coasts by reducing erosion and the energy of rainfall, storm surge, and tidal flooding. Permeable surfaces and natural features (such as marshes and trees) allow stormwater absorption to reduce flooding. These features also increase groundwater supply and improve water quality by absorbing and filtering nutrients and pollutants from stormwater runoff. Other benefits of green infrastructure include improving habitats and biodiversity, enabling upland migration of wetlands as sea level rises, beautifying cityscapes and coastlines, attracting tourism,3 providing carbon sequestration, and reducing air temperatures.4 Green infrastructure is more cost effective than traditional gray infrastructure and requires less human capital to install.5 Green infrastructure also evolves over time through natural processes, whereas gray infrastructure does not adapt to any new climate conditions beyond what it was originally designed and built to withstand. The presence of green infrastructure can increase property values when constructed on private property, and when NFIP-participating communities install green infrastructure, they can earn credits through the Community Rating System that result in reduced flood insurance premiums for their residents.6 For more information on the benefits of nature-based solutions and specific benefits of various types of green infrastructure, see the Virginia Institute of Marine Science’s Nature-Based Solutions summary.

Communities can face several barriers to implementing green infrastructure. Local government installation of shoreline stabilization measures in the intertidal zone in a mean low water state like VA requires permission from private property owners, which can make it more difficult to obtain public funds for use on privately owned lands. In addition, engineers may hesitate to certify designs for living shorelines or other engineered green infrastructure projects when there are not effective design standards in place, in case the project fails and exposes properties or critical infrastructure to flood risks. So it is important for states and localities to adopt effective design and installation standards that are tailored to their local conditions, in order to incentivize the use of green infrastructure.7

Types of Green Infrastructure:

Living Shorelines

NOAA defines a living shoreline as “a protected and stabilized shoreline that is made of natural materials such as [native] plants, sand, or rock.”1 Living shoreline methods all have the basic goal of “stabilizing” the shoreline, or protecting it from erosion. Some living shorelines will also help break up the energy from coastal waves and protect coasts against storms. As of July 1, 2020, Virginia law discourages the use of hard armoring and instead requires the use of living shorelines unless the “best available science” shows that they are not suitable.2 Virginia’s stance on living shorelines is compatible with the concept of rolling easements; for more information, see the Innovative Idea: Rolling Easements case study.

Examples of living shorelines include:3

  • Manufactured wire reefs
  • Coir logs
  • Breakwaters
  • Salt marsh grass restoration
  • Oyster reef restoration
  • Linear reef clusters
  • Coastal wetland maintenance
  • Planting native plants on natural dunes

One study found that, across 12 states, coastal wetlands reduced direct flood damages from Hurricane Sandy by $625 million.4 Research also indicates that living shorelines are more resilient than bulkheads in protecting against the effects of hurricanes; for example, North Carolina properties that used natural shoreline protection measures withstood wind and storm surge during Hurricane Irene in 2011 better than properties using seawalls or bulkheads.5

Local governments in Virginia can use the VIMS‐CCRM Coastal Management Decision Tools Decision Tree for Undefended Shorelines and Those with Failed Structures to help them choose the environmentally preferable approach for management of their shoreline. They also can consider using a locality-wide regulatory structure to encourage an integrated approach to shoreline management.

Funding assistance is available to local governments for the installation of living shoreline projects. For example, National Fish and Wildlife Foundation funds are being used to install nature-based shoreline protection and habitat restoration measures on Hog Island in Gloucester County, on property owned by the Chesapeake Bay Public Access Authority. The project is intended to reduce erosion and sedimentation into the Chesapeake Bay, protect vulnerable communities, and protect and enhance habitat. For more information, see Virginia | NFWF; Virginia’s Middle Peninsula: Projects Focus on Oysters, Shorelines, and More and CBSF-SWG-Slate-2022-Final.pdf (nfwf.org).

1 National Oceanic and Atmospheric Administration, “What is a living shoreline?,” last modified July 27, 2023, https://oceanservice.noaa.gov/facts/living-shoreline.html 2 Va. Code § 28.2-104.1, https://law.lis.virginia.gov/vacode/title28.2/chapter1/section28.2-104.1/. 3 John Rozum, “Introducing Green Infrastructure for Coastal Resilience,” National Oceanic and Atmospheric Administration Office for Coastal Management, 2019, https://www.northeastoceancouncil.org/wp-content/uploads/2019/01/Intro-Green-Infrastructure-NOAA.pdf. 4 Siddharth Narayan et al., “The Value of Coastal Wetlands for Flood Damage Reduction in the Northeastern USA,” Scientific Reports 7, art. 9463, (2017), https://www.nature.com/articles/s41598-017-09269-z. 5 John Rozum, 2019. (See 3).

Permeable infrastructure allows for the absorption of water, reducing stormwater runoff and flooding while recharging groundwater stores. Standard infrastructure, such as roads and sidewalks, is typically impermeable, meaning it does not allow water absorption and induces surface runoff during severe storm events.1

Examples of permeable green infrastructure include: 2

  • Concave green space
  • Storage ponds
  • Porous pavements
  • Bioswales
  • Grass and gravel pavers
  • Rain gardens
  • Stormwater planters

In 2014, the Town of Onancock, Virginia partnered with the Chesapeake Bay Foundation and the Center for Watershed Protection to replace one of the town’s largest parking lots with permeable pavement. Polluted stormwater runoff from parking lots was running into Onancock Creek and emptying into the Chesapeake Bay. The permeable surface allowed water to infiltrate into the ground and seep toward a vegetated area of native trees and grasses, filtering out pollutants and reducing runoff,3 thereby reducing pollution in the Chesapeake Bay watershed.

1 University of Delaware, “Permeable vs. Impermeable Surfaces,” https://www.udel.edu/canr/cooperative-extension/fact-sheets/permeable-impermeable-surfaces/.
2 John Rozum, “Introducing Green Infrastructure for Coastal Resilience,” National Oceanic and Atmospheric Administration Office for Coastal Management, 2019, https://www.northeastoceancouncil.org/wp-content/uploads/2019/01/Intro-Green-Infrastructure-NOAA.pdf.
3 Karen Cappiella, “Onancock parking lot soaks up rain for a cleaner creek.” Center for Watershed Protection, June 4, 2014, https://www.prlog.org/12332556-onancock-parking-lot-soaks-up-rain-for-cleaner-creek.html. See also “Remodeled Onancock parking lot curbs runoff,” Delmarva Now, May 13, 2014, https://www.delmarvanow.com/story/news/local/virginia/2014/05/13/remodeled-onancock-parking-lot-curbs-runoff/9041255/.

Beach replenishment, or beach nourishment, is the process of adding sand to an eroding beach to widen it, protect the coast, or improve the recreational value of the beach.1 Such efforts are undertaken to absorb wave energy, protect upland areas, and mitigate erosion.2

Beach nourishment is often the government’s go-to method to protect coasts. However, it is costly and not sustainable. NOAA projects that maintaining a nourished beach over 10 years costs between $3.3 and $17.5 million per mile.3 Despite the high cost, the effectiveness of these projects too often is temporary, as storms wash away replenished sand as they batter coasts. A recent and painful example arose in 2024, when wealthy homeowners in the Massachusetts beach town of Salisbury spent nearly $600,000 on a beach replenishment project, only to see it washed away by a winter storm just three days after its completion. The Salisbury Beach Citizens for Change raised funds to bring in 14,000 tons of dredged sand to build dunes to protect homes and infrastructure. While it may have protected some homes during the storm, the group’s efforts were entirely washed away, leaving their coast vulnerable once again.4 To help Salisbury after the storm, the State of Massachusetts committed $1.75 million to bring 30,000 tons of sand to mitigate erosion from winter storms, as part of a long-term $6 million strategic plan to improve coastal resilience.5

In another instance, in 2023, Avalon, New Jersey spent $1.1 million on 550,000 cubic yards of sand to replenish its beaches, which washed away within the year. The locality spends approximately $600,000 per year importing sand to renew its coasts.6 As of 2022, New Jersey is estimated to have spent over $3 billion on beach nourishment and has replenished its beaches over 350 times since 1938.7 These examples demonstrate that, while beach nourishment can help to support tourism and can provide a temporary buffer, it is not a viable option for long term community resilience without undertaking repeated replenishment efforts, at great expense. Recognizing this, the Dutch developed the innovative Sand Motor “mega- nourishment” project off the Delfland coast on the North Sea, creating a peninsula to preserve the coastline and protect against flooding.8 The project uses natural processes to distribute the sand and is expected to provide the equivalent of 20 years’ worth of regular beach nourishment.9 In addition, in the mid-Atlantic region, the Virginia Department of Energy and the United States Bureau of Ocean Energy Management have been researching the potential extraction of heavy minerals from marine sand deposits during dredging and beach nourishment operations to help offset the costs of beach replenishment. For more information, see the Virginia Department of Energy’s “Proceedings of the 2022 Mid-Atlantic Marine Heavy Mineral Sands Forum.”

An example of beach erosion with a different resolution is Rodanthe, North Carolina, where homes formerly on upland have been collapsing into the ocean and more are projected to follow. Rodanthe residents have requested that Dare County take action to nourish their beaches, but County officials estimate that a one-time beach replenishment could cost as much as $40 million, while nourishing the beach over the next thirty years could cost more than $175 million.10 In addition, a study by the Program for the Study of Developed Shorelines at Western Carolina University found that removing Rodanthe’s most-threatened structures would give the village a viable beach for 15-25 years, versus five years or less provided by a nourishment project.11 The village is trying to determine the next best steps to keep residents safe and also safeguard the tourism industry and economy. In the meantime, the National Park Service notes on its website for the Cape Hatteras National Seashore that many private properties adjacent to the beach in Rodanthe are partially or fully covered with ocean water on a regular basis, and six houses there have collapsed in recent years;12 so the NPS has purchased and removed structures on two threatened oceanfront properties as a pilot for potentially more purchases, and to provide public beach access.13

Another approach is used by the Sandbridge community in Virginia Beach, where residents approved imposition of a fee on themselves decades ago to fund beach replenishment via the creation of the Sandbridge Special Service District.14 Beach nourishment has been largely successful for the community, thus funds collected from local residents are used to finance a long-term beach nourishment program. For more information, see Step 5 and pages 39-42 of the Virginia Beach Beaches and Waterways Advisory Commission’s Management Plan.15

Assateague Island, a barrier island located along the coasts of Maryland and Virginia, has moved westward due to a process called island rollover. Storms, wind, and wave action have slowly moved sediment, pushing the island well over 350 meters toward the coast. The island’s westward movement has been exacerbated by the installation of jetties on Assateague island in the 1930s, which drastically increased sediment erosion. To combat this problem, a group of officials created a two-stage restoration plan for Assateague. The first stage replenished lost sediment using a one-time beach nourishment: in 2002, officials deposited 1.4 million cubic meters of sand on Assateague Island to replace a portion of the sand lost due to the effects of the jetties. The second stage addresses future sediment loss due to the jetties through long-term beach replenishment. Since 2004, Assateague has deposited dredged sediment twice per year to maintain a supply of sediment. For more information, see the National Park Service’s Assateague Island Restoration Project Introduction.16

Dutch Sand Motor Project (Photo from Elizabeth Andrews)

1 Casey Hedrick, “State, Territory, and Commonwealth Beach Nourishment Programs; Executive Summary” National Oceanic and Atmospheric Administration, March 2000, https://coast.noaa.gov/data/czm/media/finalbeach.pdf. 2 U.S. Army Corps of Engineers Institute for Water Resources, “Beach Nourishment,” https://www.iwr.usace.army.mil/Missions/Coasts/Tales-of-the-Coast/Corps-and-the-Coast/Shore-Protection/Beach-Nourishment/. 3 Casey Hedrick, 2000. (See 1). 4 Michael Casey, “Massachusetts town spent $600K on shore protection. A winter storm washed it away days later,” News Center Maine, March 13, 2024, https://www.newscentermaine.com/article/news/regional/massachusetts/massachusetts-town-spent-600k-on-shore-protection-it-washed-away-three-days-later/97-1d2a8b87-e307-456c-b948-866a40217db3. 5 Beth Treffeisen, “State comes through with $2 million for erosion repairs at Salisbury Beach,” Boston.com, May 21, 2024, https://www.boston.com/news/travel/2024/05/21/state-delivers-salisbury-beach-2-million-for-repairs/. 6 Steven Rodas, “Jersey Shore town spent $1M to fix its beach last spring but nearly all the sand washed away,” NJ.com, April 03, 2024, https://www.nj.com/cape-may-county/2024/04/wealthy-jersey-shore-town-spent-1m-to-fix-beach-last-spring-but-nearly-all-the-sand-washed-away.html. 7 “New Jersey Beach Nourishment,” Western Carolina University, https://beachnourishment.wcu.edu/state/NJ. 8 European Environment Agency, “Sand Motor: Building with Nature Solution to Improve Coastal Protection Along Delfland Coast, the Netherlands,” 2018, https://climate-adapt.eea.europa.eu/en/metadata/case-studies/sand-motor-2013-building-with-nature-solution-to-improve-coastal-protection-along-delfland-coast-the-netherlands. 9 Ibid. 10 Gareth McGrath, “Study says buyout of threatened Outer Banks homes would be cheaper than beach nourishment,” StarNews Online, June 27, 2023, https://www.starnewsonline.com/story/news/local/2023/06/27/north-carolina-beach-houses-on-outer-banks-are-threatened-are-buyouts-the-answer/70317382007/. 11 Ibid. Also see “The Potential Cost/Benefits of Buyouts in Rodanthe, North Carolina,” Western Carolina University, https://psds.wcu.edu/projects-and-research/municipalprojects/rodanthe-buyout-study/. 12 National Park Service, “Threatened Oceanfront Structures,” last modified May 28, 2024, https://www.nps.gov/caha/learn/news/threatened-oceanfront-structures.htm. 13 Ibid. 14 Va. Beach Code of Ordinances “Chapter 35.1: Stormwater and Erosion Control,” https://library.municode.com/va/virginia_beach/codes/code_of_ordinances?nodeId=CO_CH35.1SASPSEDI. 15 Beaches and Waterways Advisory Commission, “Virginia Beach Management Plan,” April 2002, 39-42, https://s3.us-east-1.amazonaws.com/virginia-beach-departments-docs/planning/Comprehensive-Plan/Documents-Adopted-by-Reference/Beach-Management-Plan-2002.pdf. 16 National Park Service, “Assateague Island National Seashore North End Restoration Project Introduction,” https://www.nps.gov/asis/learn/nature/upload/projectintroduction.pdf.

 

Helpful Tools/Resources:

Funding for Green Infrastructure:

Gray Infrastructure

Gray infrastructure is traditional stormwater infrastructure in the built environment, such as gutters, drains, pipes, bulkheads, rip rap revetment, dikes, levees, seawalls, and retention basins.8 Gray infrastructure provides protection from severe weather events, and traditional stormwater management infrastructure is able to quickly drain stormwater to prevent on-site flooding.9 However, gray infrastructure requires high up front costs for installation; it can take a long time to design, obtain funding for, and install; and, unlike green infrastructure, it does not adapt to new climate conditions beyond what it was originally designed and built to withstand.10 Gray infrastructure also is generally considered an eyesore, which may generate community concern. Importantly, it can give water nowhere else to go, which can worsen flooding. Once a stormwater management system has surpassed the volume it can handle, it pushes water to unprotected areas, creating runoff that collects pollutants as it washes over impervious surfaces. That runoff ultimately flows into and pollutes the environment.11

Gray infrastructure also can negatively impact the surrounding landscapes and ecosystems. For example, Assateague Island, a barrier island along the coasts of Virginia and Maryland, was breached by a storm in 1933, creating an inlet that split the island into two separate islands, Assateague and Fenwick. Local officials installed jetties along the coasts of the two islands to form a navigable waterway from the inlet. The construction of the jetty on Assateague Island drastically increased erosion and inhibited longshore sediment transport, causing the island to lose large amounts of sediment without recovering it.12 Due to this, the destabilized shoreline has migrated at an unnatural rate, creating large scale landscape and habitat changes.13 Much of the island’s salt marsh has been destroyed since the installation of the jetties, which is habitat for several endangered species on the island.14 The island has also become very vulnerable to breaching during storms due to the loss of sediment.15 Officials have implemented a two-step plan to restore the island using beach nourishment. See the Green Infrastructure – Beach Replenishment section above for more information.

New Orleans has discovered that gray infrastructure can come with a plethora of unintended consequences. The most costly of these is that New Orleans is sinking.16 While the gray infrastructure has been good for combating some effects of storm surge outside of city boundaries, any water that does land in the City causes severe issues. New Orleans pumps its groundwater out so stormwater can be absorbed into the ground without flooding the streets, but this pumping causes the soil to compress and sink.17 Normally, this sediment would be replaced by the Mississippi River, but the floodwalls and levees prevent this from happening. Due to land subsidence, more groundwater has to be drained to prevent flooding, leading the land to subside more, and so on, creating a detrimental cycle.18 Furthermore, the pumps are often clogged by debris which prevents the gray infrastructure from operating at full capacity.19 As a result, New Orleans is looking to shift towards green infrastructure.

As mentioned in the Green Infrastructure: Living Shorelines section, Virginia law discourages the use of hard armoring and instead requires the use of living shoreline approaches unless the best available science shows that they are not suitable. The Virginia Marine Resources Commission’s Tidal Wetlands Guidelines explain that if living shorelines are proven to not be a suitable solution for a coastal locality and gray infrastructure has to be implemented, then riprap or rock revetments are the preferred alternative. Vertical retaining structures such as seawalls and bulkheads reflect wave energy, impacting surrounding coastlines and ecosystems, and barricade tidal wetland migration. Meanwhile, riprap revetments better absorb and dissipate wave energy while creating habitat for small aquatic life. For more information, see pages 10-11 of the VMRC Tidal Wetlands Guidelines.20

Case Studies:

The City of Charleston, S.C. is pursuing the extension of one of its key seawalls. This project, known as the Peninsula Perimeter Protection Project, faces several challenges that can arise in gray infrastructure projects.1 Not only will the eight mile long, twelve foot high seawall cost over $1 billion, but it will end before it protects some of the area’s most vulnerable communities.2 Two areas that will not be protected are the majority Black, lower income neighborhoods of Bridgeview and Rosemont. The benefit-cost analyses used by the US Army Corps of Engineers consider the value of protected buildings and infrastructure, and due to the low value of buildings in the towns, they could potentially receive significantly less federal protection than affluent areas, raising significant environmental justice concerns.3 Furthermore, the height of the wall is not based on projected worst case scenario storm surge levels, meaning that the seawall may not even be sufficient to protect the areas it will serve.4 For more information, visit Charleston’s Peninsula Coastal Storm Risk Management project site.5

Norfolk, Virginia also is planning on building additional seawalls. The City sits near the mouths of the James and Elizabeth Rivers close to the Chesapeake Bay. It is home to the largest naval base in the world and one of the largest international shipping ports in the United States.6 To protect its residents and infrastructure from coastal flooding and extreme storm events, the City has developed a $2.6 billion climate resilience project known as the Resilient Norfolk Coastal Storm Risk Management (CSRM) Project.7 Norfolk’s feasibility study began in 2016 and the project is still in progress. The five-phase project includes four seawalls, several tide gates, pump stations, and levees, and localized home and commercial modification efforts.8 Other concerns are that the seawalls will degrade water quality, potentially harming nearby ecosystems, and may make flooding worse elsewhere, as they are likely to deflect storm surges along the Elizabeth River to the nearby minority neighborhoods of Berkley and Campostella, which are not protected by the proposed seawall.9 However, as of 2023, Norfolk requested the Army Corps of Engineers adjust its cost-benefit analysis method to not solely consider building value, but also broader benefits such as protecting community history. Using this revised cost-benefit analysis, Norfolk officials seek to extend the sea wall project to cover Berkley and Campostella.10 

Norfolk project planners have prioritized community outreach, creating informational materials for the community and hosting nearly 70 public events. Community outreach allowed residents from Southside, a majority-Black and lower income area that had limited protection in the initial resilience plan, to advocate for seawall protection for their community. Norfolk project officials have identified nearly 200 challenges just within the first phase of their proposed resilience plan, one being necessary relocation of old utility lines. For more information, see the Post and Courier “Holding back the sea: Norfolk’s approach to flooding offers Charleston insight” article.11

Key Takeaways:

  • Relying primarily on the property value of buildings when conducting a benefit-cost analysis for a project can create environmental justice concerns, because it can result in excluding communities with lower housing values. Considering additional metrics such as lives saved and culture preserved as additional benefits deserving local investment could create a more equitable outcome.
  • Accounting for worst-case scenario SLR and storm surge predictions in planning gray infrastructure will ensure that the efforts are sufficient to protect communities during hazardous events.
  • Learning from existing climate resilience and gray infrastructure projects may help Virginia localities planning their own gray infrastructure projects.

Cuba has made nature-based solutions the central tool for building coastal climate resilience. It made this decision in light of gray infrastructure failures, such as the Havana seawall becoming insufficient to protect the City from rising sea levels. Green infrastructure, including mangrove restoration, is seen as a more effective climate resilience strategy because of its ability to stabilize shorelines more effectively and remove carbon from the atmosphere. Additionally, the Cuban government recognized that nature-based solutions would provide them with significant cost savings compared to gray infrastructure.1

See the full Cuba’s Tarea Vida case study, which details the importance of nature-based solutions in creating resilient coastlines and communities.

1 Katherine Angier, “Three lessons from Cuba about improving coastal climate resilience,” Environmental Defense Fund, April 4, 2019, blogs.edf.org/growingreturns/2019/04/04/cuba-lessons-coastal-climate-resilience/.

Citations for This Page

1 National Oceanic and Atmospheric Administration, “Natural Infrastructure,” last modified July 9, 2024, https://coast.noaa.gov/digitalcoast/topics/green-infrastructure.html.
2 Federal Emergency Management Agency, “Nature-Based Solutions,” last modified October 13, 2023, https://www.fema.gov/emergency-managers/risk-management/climate-resilience/nature-based-solutions.

3 For example, a 2024 study the Virginia Institute of Marine Science found that marshes and living shorelines in the Middle Peninsula region of Virginia generate more than $6.4 million per year in economic value for recreational fishing – more than three and a half times greater than the value associated with hardened shorelines – because surveyed anglers preferred those habitats for fishing. Andrew M. Scheld et al., “Valuing shoreline habitats for recreational fishing,” Ocean and Coastal Management 253, July 1, 2024, https://www.sciencedirect.com/science/article/pii/S0964569124001352.
4 National Oceanic and Atmospheric Administration, “What is a living shoreline?,” last modified July 27, 2023, https://oceanservice.noaa.gov/facts/living-shoreline.html. See also National Resources Defense Council, “Green Infrastructure: How to Manage Water in a Sustainable Way,” July 25, 2022, https://www.nrdc.org/stories/green-infrastructure-how-manage-water-sustainable-way.
5 Environmental Protection Agency, “Green Infrastructure Cost-Benefit Resources,” last modified January 18, 2024, https://www.epa.gov/green-infrastructure/green-infrastructure-cost-benefit-resources.
6 Federal Emergency Management Agency, “Reduce Insurance Costs and Conserve Species,” last modified April 1, 2022, https://www.fema.gov/floodplain-management/wildlife-conservation/reduce-insurance-cost-conserve-species#:~:text=Through%20the%20CRS%2C%20communities%20receive,be%20reduced%20up%20to%2045%25.
7 Adriana Zuniga-Teran et al., “Challenges of mainstreaming green infrastructure in built environment professions,” Journal of Environmental Planning and Management 63, (2019), https://doi.org/10.1080/09640568.2019.1605890. (Noting that uncertainty about how best to design green infrastructure is an impediment to its use, and arguing that cities need to follow a standardized green infrastructure design process using context-specific technical guidelines that they develop based on GI performance data)
8 Environmental Protection Agency, “Green and Gray Infrastructure Research,” January 9, 2024, https://www.epa.gov/water-research/green-and-gray-infrastructure-research.
9 National Association of City Transportation Officials, “Chapter 3: Fundamentals of Stormwater Management,” New Hampshire Stormwater Manual 1, (2015): 5-18, https://nacto.org/wp-content/uploads/2015/04/wd-08-20a_ch3.pdf.
10 Projects built by the U.S. Army Corps of Engineers require four congressional approvals: approval of a study; funding for the study; approval of the project; and funding for the project.
11 Environmental Protection Agency, “Leaving the Gray Behind,” June 24, 2016, https://www.epa.gov/sciencematters/leaving-gray-behind.
12 National Park Service, “Assateague Island National Seashore North End Restoration Project Introduction,” https://www.nps.gov/asis/learn/nature/upload/projectintroduction.pdf.
13 Ibid.
14 U.S. Army Corps of Engineers, “Ocean City, Maryland, and Vicinity Water Resources Study. Final Integrated Feasibility Report and Environmental Impact Statement. Appendix D Restoration of Assateague Island,” June 1998, 2-15. https://www.nab.usace.army.mil/Portals/63/docs/Civil%20Works/Restoration_of_Assateague.pdf.
15 Ibid., 3-2.
16 John Sabo, “Why Engineering With Nature Could Save New Orleans And The Mekong Delta,” Forbes, December 16, 2022, https://www.forbes.com/sites/johnsabo/2022/12/16/why-engineering-with-nature-could-save-new-orleans-and-the-mekong-delta/.
17 Laura Nougues, and Roelof Stuurman, “Groundwater drainage in New Orleans,” Amsterdam International Water Web, September 21, 2022, https://www.amsterdamiww.com/best-practices/groundwater-drainage-in-new-orleans/.
18 Ibid.
19 Leah Campbell, “How New Orleans neighborhoods are using nature to reduce flooding,” Prevention Web: United Nations Office for Disaster Risk Reduction, June 9, 2022, https://www.preventionweb.net/news/how-new-orleans-neighborhoods-are-using-nature-reduce-flooding.
20 Va. Marine Resources Commission, “Tidal Wetlands Guidelines,” May 2021, 10-11, https://www.mrc.virginia.gov/regulations/Final-Wetlands-Guidelines-Update_05-26-2021.pdf.

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