Peninsula Perimeter Protection Project

With increasing frequency every year, the City of Charleston finds itself under water. We are on the front lines of a changing climate and sea level rise. Stronger and more frequent rain events, higher seas pushing water further inland with extreme high tides, dangerous storm surges from hurricanes, and groundwater inundation from a rising water table all contribute to one of the most urgent threats of our time: flooding.  

Charleston is no stranger to catastrophic storms or flooding. Since its settlement by Europeans three-and-a-half centuries ago, man has tried to battle nature in an attempt to keep water from getting onto the land and flooding homes. Creeks and marshes have been filled, walls have been constructed, and massive tunnels and pump stations have been engineered to try and keep our city dry. And now, Charleston faces projects that amount to billions of dollars to try and keep up with this pace.  

The Peninsula Perimeter Protection Project, which began as US Army Corps of Engineers (USACE) 3x3x3 project, was initiated in response to the vulnerability of the Charleston peninsula to flood risks from sea level rise, high tides, increasingly stronger storms, and storm surge. In 2018, the USACE—with authorization from Congress—completed a study to examine the coastal storm risk of the Charleston peninsula. After nearly four years of study, the USACE recommended an eight-mile seawall to wrap around the Charleston peninsula. Included in the recommendation was a 4,000 foot breakwater located offshore of the Battery, a few supplemental nature-based features, and vague nonstructural measures for vulnerable communities excluded from the protection of the proposed seawall.  


USACE projected modeling of Hurricane Hugo-type surge impacts on the peninsula in year 2082 without the project (left) and with the project (right). Image courtesy of Charleston Peninsula Storm Risk Management Study from USACE.


The Coastal Conservation League had many concerns with the initial proposal by the USACE on its appropriateness and effectiveness for the area, it’s inclusivity of vulnerable communities, and the disconnect it would create between people and the water in our coastal city. However, we are encouraged by recent updates that appear to respond to many the concerns raised by Charlestonians throughout the process thus far. We look forward to learning more about the future of the project in 2024. 

The Latest 

Currently, the City of Charleston is in negotiations with the USACE to reach a design agreement and enter the Pre-construction, Engineering, and Design (PED) phase of the project. The Conservation League maintains that it is vital that any plan the City of Charleston agrees to proceed with will incorporate green infrastructure and multifunctional elements incorporated throughout the proposed project to maintain and enhance the community’s connections with the water while also improving overall resilience. 


A design idea in the Peninsula Coastal Storm Risk Managamenet project FAQ that shows an example of what a portion of the seawall could look like with green infrastructure. This mock up is of the Joe Riley Waterfront Park. Image courtesy of City Design Division.


Wherever and whenever possible, the City of Charleston – and the greater Lowcountry – should be adapting to live with water by creating parks that can double as protective barriers against floodwaters, restoring former creeks, elevating structures, utilizing natural green infrastructure, re-naturalizing the floodplains, and determining where hard armoring may be necessary on a site-specific basis.  

Alongside the Peninsula Perimeter Protection Plan, the City of Charleston and USACE announced in September 2023 the launch of the Tidal and Inland Flooding Feasibility Project that will assess stormwater and tidal flooding across the city. This new project addresses the concerns of citizens who live in areas outside of the Charleston Peninsula, but also still face increased flooding from heavy rain and tidal events. 

Additionally, the City of Charleston is developing a Comprehensive, Integrated Water Plan (CWIP) through a selected team of engineers, architects, landscape architects, and ecologists. The Water Plan will develop strategies, projects, and policies that will address the increasing risk of flooding from high tides, sea level rise, stormwater, storm surge, and groundwater within the Urban Growth Boundary.  



Corps of Engineers Proposes a Seawall around the Charleston Peninsula 

In April 2020, the US Army Corps of Engineers released a draft feasibility report and environmental assessment to address coastal storm risk for the Charleston Peninsula. The initial comment period to provide feedback on the proposed project closed June 19th, 2020. A second comment period was open late in the first quarter of 2021.  

This study is the result of the federal planning process referred to as the 3x3x3 process consisting of a study that costs $3 million to complete within three years and includes three concurrent levels of review. In Charleston, the Army Corps was tasked with identifying a buildable project to protect the peninsula from flooding caused specifically by storm surge.  

Following 18 months of data collection, modeling, and analysis the Army Corps is proposing to construct a nearly eight-mile seawall around the perimeter of the peninsula approximately three feet higher than the current height of the High Battery seawall. The seawall would require at least five pump stations to be constructed to pump water outside the wall. In total, the project would impact nearly 111 acres of marsh.  

Also included in the USACE recommendations is a 4,000-foot-long breakwater located offshore by the Battery. In addition, nonstructural measures are being proposed to address nearly 100 houses located outside of the wall in the Rosemont and Bridgeview Village communities. The specific definition of nonstructural measures was not included in the report beyond potential options ranging from elevating, ‘floodproofing’, relocating, or buying-out homes.  

In June 2020, the Conservation League facilitated a webinar with our partners at Charleston Waterkeeper, Groundswell Charleston, Historic Charleston Foundation, Preservation Society of Charleston, and The Nature Conservancy to provide a platform for the public to hear from the Army Corps of Engineers and the City of Charleston about the 3x3x3 project. You can watch that recorded webinar by clicking here. 

Additionally, On June 19, 2020, the Coastal Conservation League and the Southern Environmental Law Center, along with Charleston Waterkeeper, the South Carolina Wildlife Federation, Audubon South Carolina, and the South Carolina Environmental Law Project submitted comments to the Army Corps on its seawall proposal. (See our full comment letter at the bottom of this page.) In our comments, we pointed out some significant flaws and concerns, including:  

  • The lack of a robust environmental review. The Corps inexplicably concluded that the seawall will not have a “significant” impact on the human environment, and therefore doesn’t need an Environmental Impact Statement (EIS) that would require the Corps to rigorously explore and objectively evaluate reasonable alternatives. In fact, because the current proposal would end up destroying or impairing national historic landmarks, significant wetlands, essential fish habitat, and more, the Corps is legally required to prepare a full EIS to thoroughly examine and describe its plans to avoid and minimize harm to these precious resources.  
  • A reliance on “grey infrastructure.” The proposal focuses only on human-engineered solutions like concrete seawalls, ignoring nature-based solutions or green infrastructure that could deliver multiple benefits, including buffering from storms and added flood storage capacity. Instead of building a single-purpose, uniform wall, the Corps should carefully evaluate solutions that create multiple benefits and are tailored to the unique needs of different areas of the peninsula.  
  • Incomplete or inaccurate data and assumptions. The proposal ignores important sources of flooding on the peninsula which are also tied to strengthening coastal storms, such as more intense rainstorms, tidal flooding, and groundwater inundation. It also underestimates likely future sea level rise, creating the danger of building a costly seawall that can’t even achieve its stated goal of protecting the peninsula from storm surge.  
  • Uncertainty about unprotected areas. The Army Corps doesn’t explain how communities outside the proposed seawall will be protected. The exclusion of a number of working class communities from the seawall perimeter shows that the Corps has not appropriately considered environmental justice issues. It also hasn’t adequately evaluated the potential for damage from wave deflection to communities west of the Ashley River or east of the Cooper River, the risks of catastrophic failure or overtopping of the seawall, or the damage to wetlands.  
  • High cost. The proposal is biased toward costly, environmentally damaging grey infrastructure when less expensive, nature-based solutions are available, and the projected cost is incomplete and probably underestimated.  

The nearly $2 billion proposal from the Corps, of which the city would have to pay just over a third, is focused solely on one problem: defending the peninsula from storm surge. While storm surge is a major concern, Charleston faces many other flood threats that interact with and exacerbate damages in coastal storms. With a price tag this massive, the Corps should take a more holistic approach to flooding and should find solutions that create greater benefits for the community.  

In 2019, the citizens of Charleston chose a broader approach than just a wall, adopting the “Dutch Dialogues” as guiding principles for living with water. The proposed wall design is inconsistent with the Dutch Dialogue principles, but we remain hopeful that this process and the discussions that will continue between the Corps, Charleston’s leaders, and, most importantly, the city’s residents will result in an approach that addresses the proposal’s shortcomings and results in effective solutions. The best way to ensure that outcome is to engage in a robust review that a proposal of this magnitude deserves.  

Beyond the Wall  

In 2021, the Coastal Conservation League and the Southern Environmental Law Center (SELC)worked with Sherwood Design Engineers, a San Francisco-based firm with extensive experience working on resilience projects around the country to analyze the Army Corps’ Draft Feasibility Report/Environmental Assessment (“EA”) for the Charleston Peninsula Coastal Flood Risk Management Study, also known as 3x3x3. Sherwood has compiled their recommendations and ideas for ways that the Corps can better utilize natural and nature-based solutions in their shoreline protection on the peninsula in a new report titled, Beyond the Wall.   

Beyond the Wall provides a range of nature-based alternatives that address storm surge and other sources of flooding while delivering additional benefits such as recreational amenities. These alternatives are more in keeping with the character of the city than the proposed seawall, which would sever residents’ connection to the water. While this report only looks at three specific areas, the Battery, Lockwood Boulevard, and Rosemont, these areas are three places that represent ways to embrace a more natural approach where the Corps currently proposes a seawall or simply raising homes. However, the recommendations in each section can be applied to other locations within the Corps’ study area and should be viewed as part of the menu of potential ideas as the City of Charleston and Army Corps of Engineers continues to analyze and evaluate the best approach to perimeter protection around the Charleston peninsula.

Environmental Impact Statement (EIS) Public Engagement 

Thanks to the broad and diverse public engagement last year that advocated for a more thorough evaluation of the Corps’ seawall proposal, an Environmental Impact Statement (EIS) was initiated earlier this year. A draft EIS will soon be unveiled to the public for review and another round of public comments. We encourage people to review Beyond the Wall and submit comments during this engagement period to advocate for more natural and nature-based solutions to be incorporated in areas where that is appropriate and to abandon the Corps’ one-size-fits-all approach that considers only a concrete seawall around the peninsula.  

Below are suggested talking points to incorporate into public comments for the upcoming draft EIS:  

  • The Corps should divide the study area into sections in order to identify areas on the peninsula where natural or nature-based, layered strategies to address flooding can be incorporated per Sherwood’s recommendations.  
  • The Corps’ current recommendation do not address the city’s most pervasive flooding problems, including chronic tidal flooding and intensifying rain events combined with a low-lying, aging stormwater drainage system. The Corps’  seawall approach is expensive and will take resources away from other, present day needs. Therefore, an area-specific approach should look at the context of that smaller section and assess whether nature-based solutions can be utilized that are multi-functional and address both storm surge and other flooding issues.  
  • The Corps’ current economic analysis fails to account for the benefits and services of nature-based solutions and is skewed in favor of affluent communities. There needs to be more transparency as to why neighborhoods like Rosemont and Bridgeview Village were excluded from the proposed perimeter protection.  
  • The Corps’ and the City of Charleston should begin now to work directly with communities like Rosemont and Bridgeview Village to develop community-led resilience plans to develop more equitable solutions for long term flood mitigation in neighborhoods that have historically been left out of the conversation.  

Contact Us

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