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Executive Order 11988 (“Floodplain Management”) requires the National Park Service and other 

agencies to evaluate the likely impacts of actions in floodplains. This statement of findings (SOF) has 

been prepared to comply with EO 11988. 

In managing floodplains on park lands, the National Park Service policy is to (1) manage for the 

preservation of floodplain values; (2) minimize potentially hazardous conditions associated with 

flooding; and (3) comply with the NPS Organic Act and all other federal laws and Executive Orders 

related to the management of activities in flood-prone areas (Management Policies Sec. 4.6.4). This SOF 

is considered a part of the Environmental Impact Assessment associated with the National Mall Plan. 

PROPOSED ACTION

The National Park Service proposes to implement the preferred alternative of the Final National Mall 

Plan / Environmental Impact Statement. 

The National Mall Plan performs two critical functions for Park Service managers. First, by describing 

specific desirable resource conditions and visitor experiences for the National Mall, it establishes a 

clear direction for management of resources and visitation. Second, the management plan provides a 

framework to guide park management decision-making for up to 50 years. The National Mall Plan was 

developed in consultation with interested parties including federal, state, and local agencies as well as 

the public. 

The plan provides overall direction for park management but specific actions needed to implement the 

plan will be provided in subsequent plans. Because the plan is general in nature, floodplain analysis is 

also general. Site-specific environmental analysis and compliance documentation will be completed 

for individual actions prescribed in the plan. 

The preferred alternative will continue to use and retain existing facilities in floodplain areas within 

the park. One additional visitor facility is planned within the floodplain. Other construction will be 

replacement of existing facilities. Land use patterns and visitation levels will not change appreciably 

from current situations. 

SITE DESCRIPTION AND BACKGROUND

The National Mall is located along the Atlantic seaboard. The majority of precipitation comes in the 

form of rains with some typically minor winter snows. Extended storms are capable of dropping 

several inches of rain in a 24 to 48 hour period which can cause temporary flooding of low-lying areas. 

Floodplains in the planning area are associated with the Potomac and Anacostia rivers. Most of the 

southern portions of the planning area were created from fill dredged from the rivers or the 

Washington Channel. These areas remain as low-elevation flats within the identified floodplains. 

Occasionally, extreme high tides will result in a tidal flow up the Potomac River from Chesapeake Bay 

and cause overflowing of the river banks or the Tidal Basin. High water events have led to inundation 

of relatively small areas of open lawns and playing fields. 

The Federal Emergency Management Agency (FEMA) has identified 100-year and 500-year flood 

hazard areas in the District of Columbia (see Floodplains map; the 500-year floodplain is slightly larger 

than the 100-year floodplain shown). 
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Figure SOF-1. Floodplains Map 

Development within the floodplains includes primary and secondary roads, monuments, visitor 

services (restrooms, information kiosks, food services, etc.), sidewalks, and park operation facilities. 

Some structures are historic, and moving them would be considered an adverse effect. The Lincoln 

Memorial, Jefferson Memorial, and Washington Monument are built on elevated ground and are out 

of the floodplain. 

These facilities are determined to be in Action Class I according to the definitions in Director’s Order 

77-2: “Class I includes the location or construction of administrative, residential, warehouse and 

maintenance buildings, non-excepted parking lots or other man-made features, which by their nature 

entice or require individuals to occupy the site, are prone to flood damage, or result in impacts to 

natural floodplain values. Actions in this class are subject to the floodplain policies and procedures if 

they lie within the 100-year regulatory floodplain (the base floodplain).” 

JUSTIFICATION FOR CONTINUED USE OF THE FLOODPLAIN

As described above, some of the park development is in the 100-year or 500-year floodplains. Development and public use in these areas has been in place for many years. The situations that lead up to 

flooding of the rivers, and the scope and duration of high water events are well known by park staff. 

Actions proposed in the preferred alternative include the retention of roads, monuments, visitor 

services, and park operation facilities within 100-year and 500-year floodplains. The facilities are 

historically and functionally dependent on their locations. 

Moving entire developed areas out of the floodplains would be cost-prohibitive and would adversely 

affect historic resources. 
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SPECIFIC FLOOD RISKS

Conditions associated with flooding in the locations discussed in this statement are not considered 

particularly hazardous to people or property. Flooding generally occurs gradually in the planning area 

as a result of prolonged rainfall, making warning and evacuation a practical option for protection of 

human life. 

Park development in the floodplains has been in place for many decades and the situations, scope, and 

duration of flooding of the rivers are well known by park staff. The timing, depth, and velocity of 

floodwaters will be considered when preparing evacuation plans. 

An evacuation plan will be prepared to identify high ground safe areas and evacuation routes for each 

area of visitor concentration. In the event that it should become necessary to evacuate visitors and NPS 

personnel, it could be readily accomplished along the many access roads. 

There will be no additional storage facilities for fuels or toxic materials, or museum collections in a 

floodplain as a result of the preferred alternative. 

MITIGATION

An evacuation plan for each developed area in a floodplain will be prepared to identify high ground 

safe areas and evacuation strategies. Water levels will be monitored by park staff and, if flooding is 

imminent, visitors will be informed of evacuation procedures. 

No major new construction in floodplains is prescribed in the preferred alternative. Nonetheless, sitespecific environmental analysis will be conducted for all construction and will address potential 

impacts to floodplains. 

SUMMARY

The National Park Service has determined that implementing the preferred alternative will not result 

in any additional disruption of floodplains. Risk to life from flooding is minimal and can be mitigated. 

The National Park Service will allow existing structures to remain in their current locations because 

there are no reasonable alternative locations. One additional visitor facility is planned within the 

floodplain. Other construction will be replacement of existing facilities. Water levels will continue to 

be monitored by park staff. Visitors will be informed of changes caused by heavy precipitation events 

through regular interpretation and local media. 

Therefore, the proposed action will not have any additional adverse impacts on floodplains and their 

associated values. 

The environmental impact statement, this statement of findings for Executive Order 11988, and the 

signed record of decision complete the requirements of the National Environmental Policy Act for the 

National Mall Plan.

STATEMENT OF FINDINGS REFERENCES

Executive Order 11988, "Floodplain Management" (May 28, 1980). 

National Park Service, U.S. Department of the Interior 

2003 Director's Order 77-2: Floodplain Management. Washington, DC. 

2006 Management Policies. Washington DC.