The full report and other reports regarding the National Flood Insurance Program are on this webpage. Below is the executive summary of the report:
The Association of State Floodplain Managers has developed an estimate, based on a careful analysis, of the total cost to provide floodplain mapping for all communities in the nation based on the parameters specified in the Biggert-Waters Flood Insurance Reform Act of 2012. The Nation has invested $4.3 billion in flood mapping to date, and has enjoyed multiple benefits from that investment, including providing the basis for guiding development that saves over $1 billion/year in flood damages. ASFPM has identified criteria of what constitutes adequate flood mapping for the country, and has produced an estimate showing the initial cost to provide flood mapping for the nation ranging from $4.5 billion to $7.5 billion. The steady-state cost to then maintain accurate and up-to-date flood maps ranges from $116 million to $275 million annually. This national investment in a comprehensive, updated flood map inventory for every community in the nation will drive down costs and suffering of flooding on our nation and its citizens, as well as providing the best tool for managing flood risk and building sustainable communities.
 These estimates do not include revenue from the Federal policy fee which is primarily used to support administrative cost including the issuance of letter of map change, program management, and data dissemination.
Thanks to Bill Cumming for this citation.