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DC Coastal Study

The objective of the Middle Potomac – Washington, DC and Metropolitan Area Coastal Flooding Feasibility Study (DC Coastal Study) is to investigate coastal flooding problems and potential solutions for the Middle Potomac and Metropolitan Washington, D.C. region. 

DC Coastal Study is a three-year, $3-million study cost-shared evenly between the U.S. Army Corps of Engineers, Baltimore District, and the Metropolitan Washington Council of Governments (MWCOG). The National Capital Planning Commission (NCPC) serves as a study advisor and will help coordinate federal participation. The effort is a spin-off of the two-year North Atlantic Coast Comprehensive Study (NACCS) that was completed in January 2015 and was commissioned by Congress as part of Hurricane Sandy recovery. The purpose of NACCS was to help local communities better understand their changing flood risks due to climate change and provide them tools to be better prepared for the future. The DC Metropolitan region was one of nine high-risk areas identified in NACCS as needing further analysis.  

The study area encompasses more than 57 square miles and includes portions of the District of Columbia; Prince George’s and Charles counties in Maryland; and Arlington, Fairfax, and Prince William counties, and the City of Alexandria in Virginia, all located along the Anacostia and Middle Potomac rivers. The northern boundary for the study area is Bladensburg along the Anacostia River, and Little Falls along the Potomac River in Maryland. The southern boundary is near Fort Washington along the Potomac River. 
 

The goal is to reduce coastal flood risk to vulnerable populations, properties, infrastructure, and important environmental and cultural resources considering future climate and sea level change scenarios to support resilient communities within the DC Metropolitan region.

The study will provide recommendations to reduce economic damages from coastal flooding to residences, businesses, government offices and/or national treasures through site-specific measures; and to reduce coastal flooding that disrupts critical infrastructure, services, and shared systems in these communities. These shared systems include water, energy and communication utilities; transportation hubs; federal buildings and military installations; national security facilities; and significant national monuments and cultural treasures. The region is only as protected as the weakest link in its shared infrastructure system. This study will help address those critical issues and will aid in the long‐term resilience and sustainability of the region.

 

Three overarching efforts will be performed as part of this study


  1. Assessment of the study area’s problems, opportunities and what the future conditions would be without a project ;
  2. Assessment of the feasibility of implementing system-wide coastal storm risk management solutions such as policy/programmatic strategies, storm surge barriers at selected inlet entrances, or tidal gates at selected lagoon entrances; and
  3. Assessment of the feasibility of implementing site-specific solutions, such as a combination of structural, non-structural, and natural and nature-based features, if system-wide solutions are not possible. Structural solutions include barriers, levees, etc., and non-structural solutions include wet and dry floodproofing, etc. 

Preliminary designs and cost information will be included for the assessments. 

The Corps and coastal communities could seek additional funding to implement the recommendations from this study. Depending on the expertise needed for the recommendations, the Corps or another more suitable agency may lead a project. 

 

Public Meetings

Information to be posted soon. 

 


Contact

If you have any information or datasets related to flooding or flood risk management that may be relevant to this study, including reports, photos or other digital data, as well as climate change impact analyses or studies, please share this information with the study team by sending an email to MetroDCCoastalStudy@usace.army.mil.   

DC Coastal Q&As

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The team will continue to consider ways to engage the public on this study. If you have any information or datasets related to flooding or flood risk management that may be relevant to this study, including reports, photos or other digital data, as well as climate change impact analyses or studies, please share this information with the study team by sending an email to MetroDCCoastalStudy@usace.army.mil.    

In addition, a draft report will be available for public comment around late fall 2018. 

The non-federal sponsor, Metropolitan Washington Council of Governments, will take the recommendations from the study to decide the best path forward for the region.

Coastal flood risk management recommendations outlined in this study are meant to be customizable to incorporate into local mitigation plans, so jurisdictions can consider all potential options on the table with respect to their budgets.

This study does not lead directly to project construction. The Corps and coastal communities could seek additional funding to start more refined studies or implement the recommendations. The lead agency would depend on the expertise needed based on the recommendations. 

The District of Columbia Silver Jackets is an interagency flood risk management team, led by the Army Corps, National Park Service and the District Department of Energy and Environment. It’s a unique team that leverages resources to identify and implement comprehensive and sustainable solutions to reduce flood risks around the District. The team’s priorities include flood inundation mapping and stream gauges; flood emergency planning; interior drainage flooding; levee certification and accreditation; and communication. 

Last fall, the team held an inaugural DC Flood Summit that brought together more than 150 experts. 

The team has also created a Flood Inundation Mapping tool, which consists of real-time digital maps housed on the National Weather Service’s web site that display the potential depth and extent of flooding in the DC area based on impending storms – so it shows where flooding might occur and how deep it may be.

The team is also conducting a flood risk management study for vulnerable neighborhoods along Watts Branch. The first part of the study entails modeling the potential flood threat, and the second part entails outlining potential flood risk management options. 

The Corps is leading similar studies for the Washington Navy Yard and Joint Base Anacostia-Bolling. 

All of the agencies working together as part of the DC Silver Jackets stress that it is imperative for the public to know their flood risk and take appropriate actions to reduce this risk. Even with these projects in place and studies underway, the District is still extremely susceptible to interior flooding caused by storm drains becoming overwhelmed, and there is a large transient population that may not be aware of the flood risks. We all need to work together to educate one another. 

The 17th Street closure structure is part of the Potomac Park Levee System. It is situated between the Lincoln Memorial and the Washington Monument, and it reduces risk to human safety and critical infrastructure in downtown District of Columbia from flooding of the Potomac River. It was constructed and is regulated by the Corps of Engineers, and operated and maintained by the National Park Service. Construction completion was in 2014. The 17th Street closure is a removable structure that can be erected in the event of high water to attach to the floodwalls on both sides of 17th Street and consists of aluminum panels between steel posts. 

Upcoming related work as part of Phase II plans for the levee system includes providing a small floodwall at 2nd and P streets near Ft. McNair and raising the existing grade along 23rd Street to eliminate sandbag closures at these locations. Additionally, Phase II would raise the Potomac Park Levee system up to a uniform elevation to provide flood risk reduction up to the Congressionally-authorized 700,000 cubic feet per second flow-rate event, or approximately 19 feet above sea level. These plans still need Congressional funding.  

This is a massive undertaking to assess flood risk in our nation’s capital and come up with potential solutions, all while incorporating past, current and future related efforts and working with a multitude of stakeholders.

Three overarching efforts will be performed as part of this study:

1)         Assessment of the 57-square-mile study area’s problems, opportunities and the future if a project is not implemented. As part of the scoping process during the initial phase of the study, high-risk areas within the study boundaries will be identified with federal and non-federal cost-sharing partners and stakeholders. Future conditions will account for uncertainty and changing risk over time resulting from climate and sea level change;

2)         Assessment of the feasibility of implementing various system-wide coastal storm risk management solutions such as policy/programmatic strategies, storm surge barriers at selected inlet entrances, or tidal gates at selected lagoon entrances; and

3)         If system-wide solutions are not feasible, assessment of the feasibility of implementing various site-specific solutions, such as a combination of structural (barriers, levees), non-structural (flood-proofing measures), and natural and nature-based features.

The study team will also develop preliminary designs and costs for the solutions assessed. 

There has been extensive work completed related to the vulnerability of individual jurisdictions; however, there is no comprehensive understanding in the region of how a disruption like a large-scale flood event could impact the continuity of operations of agencies.  

This study will consider past, current, and future coastal storm risk management and resilience planning initiatives and projects by the Army Corps and other federal, state, and local agencies to ensure efforts are not duplicated and that existing projects and studies can be leveraged.


The purpose of the Middle Potomac – Washington, DC and Metropolitan Area Coastal Flooding Feasibility Study is to investigate coastal flooding problems and potential solutions within more than 57 square miles in the District of Columbia and surrounding areas of suburban Maryland and northern Virginia. 

This study is a spin-off of the two-year North Atlantic Coast Comprehensive Study (NACCS) completed in January 2015 that was commissioned by Congress as part of the Hurricane Sandy recovery effort. The District of Columbia is one of nine high-risk areas that was identified in NACCS as needing further analysis. 

As part of this study, the team will investigate flood risk and identify ways to help protect vulnerable and critical assets upon which the region relies. This infrastructure includes water, energy and communication utilities; transportation hubs; federal buildings and military installations; national security facilities; and significant national monuments and cultural treasures.

Flood risk management recommendations will be outlined in the study’s report to include holistic approaches and site-specific approaches through various structural and non-structural options, along with preliminary designs and costs. The recommendations will reduce the economic costs and risks to both people and property associated with largescale flood and storm events and, therefore, will aid in the longterm resilience and sustainability of the region.