For HUD programs under which a financial transaction for a property located in a floodplain (a 500-year floodplain for a Critical Action) is guaranteed, approved, regulated or insured, any private party participating in the transaction and any current or prospective tenant shall be informed by HUD (or by HUD's designee, e.g., a mortgagor) or a responsible entity subject to 24 CFR part 58 of the hazards of the floodplain location before the execution of documents completing the transaction.