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Gaithersburg, MD Environmental Rules: Flood Zones (2026)

Some Restrictions

Compiled from the official code textEditor Martyn O'NeillLast verified September 2026

FEMA flood zone rules in Gaithersburg, MD, also called floodplain regulations or special flood hazard area (SFHA) rules, determine flood insurance requirements and elevation standards for new construction.

Key Facts

Permit required: Site development permit before any SFHA work
Enforcing official: City floodplain administrator (city manager designee)
Base flood data: County FIS dated September 29, 2006 + FIRM
Permit validity: 180 days, extendable 90 days at a time
Penalty: Municipal infraction; each day a separate offense
NFIP participation since: December 1, 1982

FEMA Flood Zone Lookup

FEMA assigns every parcel in the U.S. a flood-hazard designation on its Flood Insurance Rate Maps (FIRMs). Zones starting with A or V are high-risk Special Flood Hazard Areas where federally backed mortgages require NFIP flood insurance. Zone X indicates moderate-to-minimal risk, where insurance is optional but often recommended. Your specific zone determines insurance cost, build elevation, and permit requirements in Gaithersburg, MD.

Zone	What it means	NFIP required?
A	High-risk flood area; 1% annual chance flood, no detailed analysis.	Yes
AE	High-risk; same as A but with established Base Flood Elevations.	Yes
AH	High-risk shallow flooding (1-3 ft), usually ponding.	Yes
AO	High-risk shallow flooding (1-3 ft) with sheet flow on sloping terrain.	Yes
V	High-risk coastal zone subject to wave action (no BFE).	Yes
VE	High-risk coastal zone with wave action and established BFEs.	Yes
X (shaded)	Moderate risk; between the 1% and 0.2% annual chance flood.	Recommended
X	Minimal risk; outside the 0.2% annual chance floodplain.	No

Look up Gaithersburg, MD on the FEMA flood map

FEMA maps update periodically; verify zone before buying flood insurance or building.

Summary

Gaithersburg bars any grading, filling, new construction, substantial improvement, or watercourse alteration inside a mapped special flood hazard area until a site development permit is issued under Chapter 10. The city's own floodplain administrator, not Montgomery County, reviews every application against the 2006 flood insurance study and FIRM panels for the city.

It shall be unlawful for any person to begin any development or construction which is wholly within, partially within, or in contact with any flood hazard area established in section 10-5, including but not limited to: filling; grading; construction of new structures; the substantial improvement of buildings or structures, repetitive loss structures, including repair of substantial damage; placement or replacement of manufactured homes, including substantial improvement or repair of substantial damage of manufactured homes; erecting or installing a temporary structure, or alteration of a watercourse, until a site development permit is obtained from the city. No such permit shall be issued until the requirements of this chapter have been met.

View official code

Official source re-checked September 7, 2026: no newer edition of the code had been published (publisher’s edition: Code of Ordinances: Supplement 52 Update 1).

Full Breakdown

The City of Gaithersburg joined the National Flood Insurance Program on December 1, 1982, and Chapter 10 of the City Code has governed floodplain development ever since, most recently rewritten by Ordinance No. O-10-15 in 2015 and amended by Ordinance No. O-6-24 in November 2024. Because Gaithersburg is one of the small number of Montgomery County municipalities that exercises independent planning and zoning authority, the city's floodplain administrator, appointed by the city manager under Section 10-11, administers this chapter inside city limits rather than the county.

Special flood hazard areas are established using the flood insurance study for the county and incorporated areas dated September 29, 2006, and the accompanying FIRM panels, kept on file at the city's planning and code administration offices. Section 10-14 makes it unlawful to begin filling, grading, new construction, substantial improvement of a repetitive-loss structure, placement of a manufactured home, a temporary structure, or alteration of a watercourse anywhere in a mapped flood hazard area without first obtaining a site development permit; the permit is valid for 180 days from issuance, with the floodplain administrator authorized to grant extensions of up to 90 days at a time.

Section 10-15 requires the application to include scaled site plans consistent with Chapter 24 zoning review, existing ground elevation referenced to the FIRM datum, and delineation of flood hazard boundaries and flood protection setbacks. 04, in addition to the city permit.

Violations & Fines

Failing to obtain a site development permit before building in a flood hazard area is itself a violation of Section 10-52 and is enforced as a municipal infraction under Section 10-54, with a fine set by city council resolution for the initial violation and each subsequent day the violation continues counted as a separate offense. Before any fine, the floodplain administrator issues a written notice of violation or stop work order under Section 10-53 listing the sections violated, ordering remedial action, and advising the property owner of the right to appeal to the board of appeals.

Frequently Asked Questions

Does Montgomery County or the City of Gaithersburg regulate floodplain construction here?

The City of Gaithersburg regulates it directly. Gaithersburg is one of only two Montgomery County municipalities, along with Rockville, that runs its own independent zoning and floodplain program, so the city's floodplain administrator, not the county, reviews permits and enforces Chapter 10 inside city limits.

What work requires a floodplain permit in Gaithersburg?

Any filling, grading, new construction, substantial improvement of an existing building, manufactured home placement, temporary structure, or watercourse alteration located wholly or partly within a special flood hazard area mapped under Section 10-5 requires a Section 10-14 site development permit before work begins.

How long is a Gaithersburg floodplain permit good for?

A site development permit is valid only if actual work starts within 180 days of issuance. If more time is needed, the floodplain administrator may grant one or more written extensions of up to 90 days each, provided the flood hazard maps underlying the permit have not been revised.

Sources & Official References

[1]Gaithersburg City Code, Chapter 10 - Floodplain Management

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