Floodplains and Flood Insurance Rate Maps

What Is a Floodplain?

A floodplain is any area of land that is susceptible to being inundated by unusual and rapid accumulation of water from any source. The Floodplain Ordinance in Chapter 48 of the Arlington County Code regulates development in flood zones.

What Is a Flood Insurance Rate Map?

The Federal Emergency Management Agency (FEMA) publishes flood hazard maps, called Flood Insurance Rate Maps (FIRM), for all areas of the United States, including Arlington. The purpose of a FIRM is to show the areas in a community that are subject to flooding and the risk associated with these flood hazards.   Knowing your flood risk is the first step to flood protection.  

How do I find the effective floodplain map for my property?

As a property owner, you should be aware of the flood risk for your property.  All properties have some level of vulnerability. Knowing your flood risk is the first step to flood protection.

If you are having problems finding the flood zone information for your property, contact us, and we can help create a map for you.  Contact Elizabeth Thurber at 703-987-6546.

How Can I Reduce my Risk of Flooding?

Flooding can be a very costly disaster. The risk for flooding is affected by many variables, many of which can change over time, due to erosion, land use, weather events and other factors. The risk for flooding can vary within the same neighborhood and even property to property.  As the flooding that occurred in Arlington in 2019 illustrated, flooding occurs not only in identified high-risk areas, but may also occur in areas that may not have been identified as high risk.  More than 20% of flood claims are from low to moderate flood risk areas.

Learn more about what you can do reduce your risk of flooding, such as purchasing  flood insurance.

Development in the Floodplain

If you are planning a construction project on your property and it is in the floodplain, you may need a Resource Protection Area (RPA) or floodplain permit/review. A permit is required when a development proposal is partly or entirely with an established RPA.

  • The Water Quality Impact Assessment Data Sheet is required if the property is located within 100 feet of a stream (in the Resource Protection Area). Check the RPA map for more details.
  • A Floodplain Development Permit is required if the property is partly or entirely within the 100-year flood plain or County-required Flood Buffer Zone. Please contact the County stormwater team for more information.

Letters of Map Revision

The County-wide flood maps for Arlington are only updated periodically.  FEMA issues interim revisions to the maps for specific properties based on submittals from private property owners, developers, and from the County.  These revisions are addendums to the County-wide maps.  The approved map revisions and map changes (Letters of Map Revision (LOMR) and Letters of Map Amendment (LOMA)) can be found online at:  https://msc.fema.gov/portal/advanceSearch .

Lower Long Branch Flood Letter of Map Revision

Lower Long Branch Effective and Proposed 1% (100 year) Floodplain

Lower Long Branch Effective and Proposed 0.2% (500 year) Floodplain

Donaldson Run Conditional Letter of Map Revision

Donaldson Run Effective and Proposed 1% (100 year) Floodplain

Donaldson Run Effective and Proposed 0.2% (500 year) Floodplain

Floodplain Elevation Certificates

An Elevation Certificate is an important tool that documents your building’s elevation. If your home or business is in a high-risk area, your insurance agent will likely need an Elevation Certificate (EC) to determine your flood insurance premium. Floods mean rising water. Knowing your building’s elevation compared to the estimated height floodwaters will reach in a major flood helps determine your flood risk and the cost of your flood insurance.  An EC documents the elevation of your building for the floodplain managers enforcing local building ordinance, and for insurance rating purposes.

Arlington Certificates of Elevation

Flood Information Resources