The intensity of flooding in Huntington this summer was not anticipated because Fairfax County and Federal Emergency Management Agency were using floodplain information that was three decades old, according to a report issued Thursday by the Army Corps of Engineers.

The highly anticipated report was commissioned shortly after devastating floods struck the eastern Fairfax County locale in late June to explain why floodwaters penetrated so deeply into the community. A swift-moving wall of putrid water unexpectedly washed through neighborhoods on Arlington Terrace and Fenwick Drive, displacing scores of homeowners and causing millions of dollars’ worth of property damage.