One of the Gravity Recovery and Climate Experiment (GRACE) products, the Terrestrial Water Storage Anomaly (TWSA), was used for assessing large-scale flood risk through Reager's Flood Potential Index (RFPI) by Reager and Famiglietti (2009). The efficacy of the proposed RFPI for flood risk assessment was evaluated over the continental US using multi-year flood observation data from 2003 to 2012 by the US Geological Survey and Dartmouth Flood Observatory. In general, the flood risk based on the RFPI agreed well with the observed floods on regional and even local scales.