Well, this happens to be me a lot. For whatever reason the flood maps in my areas often state "A" but after an elevation survey is done, or a flood certification completed, it is found that the improvements are just above the flood plain and not in the flood hazard zone.
Therefore, whenever I have a house in a flood hazard area, which is common and 99% of the time it has no effect on value, I state: "The subject appears to be in a flood hazard "AE" zone, which requires flood insurance. Flood locations are common in this market and have no measurable effect on value. The determination was based on internet flood map sources and my findings yield to any contrary finding by a current and qualified elevation survey or flood certifcation. If it is determined that the subject is not in a flood zone, there would be no measurable effect on the appraised value".
Of course this statement only applies in those 99% of the cases where there is no effect.
Still, I sometimes get a request to correct the report. I don't. I simply write an addendum which states something like: "I have reviewed the flood certification for the subject property identified above and it shows the subject is located in a "X" flood hazard zone. The finding contained in the report, that the subject is in an "A" zone, yields to this more qualified determination. There are no effects on value".
The only time I will revise the actual report is if the flood location actually does have an effect on value.