FEMA Rescinds New Flood Maps for D.C.

The Federal Emergency Management Agency has rescinded maps declaring a large swath of downtown Washington and the National Mall a flood zone after city officials pledged to have a stronger levee system in place by late next year.

The new flood maps were scheduled to take effect in September. They would have led to stricter building codes, complicating the construction of federal and office buildings and forcing hundreds of homeowners to buy flood insurance.

FEMA approved the maps in March after an analysis by the U.S. Army Corps of Engineers determined that a levee system designed in the 1930s to hold back the Potomac River would not provide adequate protection during a major storm.

But in a letter Monday to Mayor Adrian M. Fenty, FEMA announced it was withdrawing the decision. The change was made after District of Columbia officials pledged to build an improved flood control system by November 2009. The city is committing $2.5 million for the project.

‘”The proposed effective date of September 26, 2008, for the Flood Insurance Study and Digital Flood Insurance Rate Map for Washington, D.C., has been suspended as a result of this action,” FEMA’s deputy administrator, Vice Adm. Harvey Johnson, wrote in the letter.

FEMA took action shortly after the D.C. government filed a lawsuit Monday against the agency in federal court. The suit calls the new flood map “arbitrary and capricious” and “unsupported by substantial evidence.”

The city’s maps for a so-called 100-year flood have not been changed since 1985, when the hazard zone was limited mostly to the area surrounding the Tidal Basin. In a post-Hurricane Katrina review, however, the Army Corps determined that the levee system running from the Lincoln Memorial to the Washington Monument was not adequate.

Without improvements, the Army Corps has estimated that a major flood could cause $200 million in damage to museums, memorials and federal office buildings.

The main problem involves a disruption in the levee at 17th Street, which cuts across the Mall near the Washington Monument.

During six previous floods, officials placed sandbags on the road to protect the city. Had there been more serious flooding, plans called for erecting an 8-foot earthen embankment with dirt taken from the grounds of the Washington Monument.

But in its review following Katrina, the Army Corps concluded that an earthen wall was not reliable and that a better system was needed.

Officials said they are considering several improvements to meet FEMA’s November 2009 deadline. They include a post-and-panel barrier, which would involve placing temporary vertical beams in the road to support metal panels that would form a wall. Other possibilities include using an inflatable dam or raising the level of 17th Street.

D.C. officials are working closely with the Army Corps, the National Park Service and the National Capital Planning Commission to select the best solution.

“Everyone agrees let’s provide this flood protection, let’s do it right away,” said Harriet Tregoning, director of the D.C. Office of Planning.

To meet the deadline, she said, construction on the improved levee system would need to begin early next year.