fldzone = 'D'

Risk tier: Undetermined.

Zone D designates areas where flood hazards are possible but have not been analyzed — no flood study has been performed, so FEMA makes no statement about the level of risk. It is neither a high-risk nor a low-risk classification; it is an explicit "unknown."

What it means in practice

D is common in sparsely populated regions where a detailed or even approximate study has never been justified. The absence of a determined hazard is not evidence of safety — the risk simply has not been studied. A parcel in Zone D could, on study, turn out to be high-risk or minimal-risk.

• No BFE exists, so staticbfe is NULL.
• Distinguish D (studied? no — risk unknown) from unshaded X (studied — minimal risk) and from a NULL fldzone (no NFHL polygon intersects the parcel at all).

Building and insurance implications

• Flood insurance is available and lenders may require it. Because the risk is undetermined, rating is based on the uncertainty rather than a known zone.
• No SFHA building requirements apply, but local due diligence is advisable before development.

zonesubty values

Zone D polygons generally carry no subtype.

In the data

SELECT lrid, parceladdr, fldzone
FROM   lr_parcel_us
WHERE  fldzone = 'D';

See also: Zone X (studied, minimal risk), Special values (including NULL).