An Associated Press review has found that thousands of people may be paying more for flood insurance or remain unaware of the dangers of dam failures because of conflicting federal policies.

The problem stems from a complex set of flood policies and some national security precautions taken after the Sept. 11, 2001, terror attacks.

To get the best discount on flood insurance, the Federal Emergency Management Agency’s points-based rating system requires communities to chart all the homes, businesses and critical facilities endangered by a potential dam failure and warn people of their risk. But that’s difficult or even impossible in some communities, because other federal agencies restrict the release of such information for hundreds of dams that they own or regulate across the U.S., citing security risks.

The quandary has persisted for years, though federal officials have been warned of its implications.

Federal “dam information sharing procedures costs communities points, homeowners money, and potentially citizens lives,” a California emergency services official warned in a January 2020 presentation to FEMA’s National Dam Safety Review Board at an invitation-only meeting attended by dozens of federal and state officials.