The Susquehanna River Basin is one of the most flood-prone areas in the nation

The Susquehanna River Basin is one of the most flood-prone watersheds in the entire nation. The main stem of the Susquehanna and its many tributaries drain 27,510 square miles of New York, Pennsylvania, and Maryland.

Since the early 1800s, the main stem of the Susquehanna has flooded every 20 years on average. Even the Native Americans who once lived in the area told of frequent floods. The Susquehanna Basin also is vulnerable to frequent, localized flash floods every year. These flash floods, usually affecting smaller tributaries, can occur with little advance warning.

Tropical storm Agnes in 1972 caused the worst recorded flooding in the Basin in June 1972. The flooding caused 72 deaths and $2.8 billion in damage. Flood levels exceeded the record levels of the 1936 flood by as much as six feet in some places. It was the nation's most costly natural disaster until Hurricane Andrew hit in 1992.

In all, 1,160 of the 1,400 communities in the river basin have some residents who live in flood-prone areas. For these residents, flood warning and flood management and protection are of utmost concern.