39 CFR 776.7: Lease, easement, right-of-way, or disposal of property to non-federal parties.

When postal property in floodplains is proposed for lease, easement, right-of-way, or disposal to non-federal public or private parties, the Postal Service shall:

(a) Reference in the conveyance document that the parcel is located in a floodplain and may be restricted in use pursuant to federal, state, or local floodplain regulations; or

(b) Withhold the property from conveyance.