Each mortgage company obtains a flood zone determination prior to the closing of a loan to determine if the property is located in a SFHA. These determinations are done by any company chosen by the lender. If the flood zone determination (right or wrong) comes back and states your property is in a SFHA then by law the lender must require flood insurance on the property.
You have a right to dispute this and once the flood zone is changed the lender will remove the requirement for flood insurance. A copy of the flood zone change must be given to the lender in order for them to remove the flood insurance requirement.