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Longmont, CO Environmental Rules: Flood Zones (2026)

Some Restrictions

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

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

Key Facts

Permit trigger: Any development in special flood hazard area
Administrator: Director of public works and natural resources
Penalty: Separate offense per day, chapter 1.12
Substantial improvement threshold: 50% of pre-improvement market value
RV exemption: On site under 180 consecutive days
Appeals body: Board of adjustment
Judicial review: Colorado Rule of Civil Procedure 106

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 Longmont, CO.

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 Longmont, CO on the FEMA flood map

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

Summary

Longmont Municipal Code section 20.12.030 requires a floodplain development permit before any building, fill, or land-use change proceeds within a special flood hazard area. The director of public works and natural resources serves as floodplain administrator, reviewing applications and enforcing standards that track National Flood Insurance Program minimums. Violators face daily fines under chapter 1.12 and nuisance injunctions, while property owners keep a variance and judicial-review path through the board of adjustment.

Sec. 20.12.030. - Establishment of floodplain development permit. A floodplain development permit shall be required to ensure conformance with the provisions of this title.
Sec. 20.12.040. - Compliance. No structure or land shall hereafter be located, altered, or have its use changed within the special flood hazard area without full compliance with the terms of this title and other applicable regulations. Nothing herein shall prevent the city from taking such lawful action as is necessary to prevent or remedy any violation. These regulations meet the minimum requirements as set forth by the state water conservation board and the National Flood Insurance Program.
Sec. 20.16.060. - Penalties for noncompliance.
(a) It is unlawful to construct, locate, extend, convert or alter any structure or land without full compliance with the terms of this title and other applicable regulations. (b) Any person committing or permitting a violation of this Code commits a separate offense for each day or part of a day during which the violation exists. Offenses are punishable according to chapter 1.12.

View official code

Full Breakdown

Chapter 20.12 sets the citywide trigger. Section 20.12.030 requires a floodplain development permit to ensure conformance with title 20, and section 20.12.040 bars locating, altering, or changing the use of any structure or land within the special flood hazard area without full compliance, noting the rules meet the state water conservation board's and National Flood Insurance Program's minimum standards. The special flood hazard area is defined in chapter 20.08 as land subject to a one percent or greater annual chance of flooding, the 100-year floodplain shown on FEMA's Flood Insurance Study for Boulder County.

Permit applications go to the floodplain administrator, designated in section 20.16.010 as the director of public works and natural resources, and under section 20.16.030 must include scaled plans, the lowest-floor elevation of new or substantially improved structures, and, for nonresidential floodproofing, a professional engineer's or architect's certification. "Substantial improvement" is defined in chapter 20.08 as reconstruction or addition work costing 50 percent or more of a structure's pre-improvement market value, and it excludes correcting existing code violations or altering a historic structure that keeps its historic designation.

Recreational vehicles are exempt from the elevation and anchoring rules under section 20.20.020(E) if they stay on site fewer than 180 consecutive days and remain fully licensed and highway-ready. Anyone seeking relief, including on a half-acre or smaller infill lot under section 20.16.040, may petition the board of adjustment for a variance, and appeals of the administrator's own decisions go to the same board under section 20.16.050, with judicial review available under Colorado Rule of Civil Procedure 106.

Violations & Fines

Section 20.16.060 makes it unlawful to construct, locate, extend, convert, or alter any structure or land in the special flood hazard area without full compliance with title 20. Each day the violation continues is a separate offense punishable under chapter 1.12. The city also treats any violation as a public nuisance the city attorney may ask a court to enjoin, on top of the criminal penalty, and the code preserves any other lawful legal or equitable relief the city may pursue.

Frequently Asked Questions

Do I need a permit to build in Longmont's floodplain?

Yes. Longmont Municipal Code section 20.12.030 requires a floodplain development permit for any construction, fill, or land-use change within a special flood hazard area, and section 20.12.040 bars locating, altering, or changing the use of a structure or land there without full compliance. Applications go to the floodplain administrator, the director of public works and natural resources, under the procedures in section 20.16.030.

What happens if I build in the floodplain without a permit?

Section 20.16.060 makes it unlawful to construct, locate, extend, convert, or alter any structure or land in the special flood hazard area without full compliance, and each day the violation continues is a separate offense punishable under chapter 1.12. The city can also treat the violation as a public nuisance and ask a court to enjoin it, in addition to the daily penalty.

Can I get a variance from Longmont's floodplain elevation rules?

The board of adjustment can grant variances under section 20.16.040, most readily for new construction or improvements on a half-acre lot or smaller surrounded by existing below-grade structures. Variances cannot be issued within a designated floodway if they would raise flood levels, and applicants must show good cause and exceptional hardship without increasing public risk or cost.

Are recreational vehicles exempt from floodplain elevation requirements?

Yes, under section 20.20.020(E). A recreational vehicle parked in a special flood hazard area is exempt from the elevation and anchoring rules if it stays on site fewer than 180 consecutive days, remains fully licensed, and is ready for highway use, meaning it sits on its wheels or jacking system with only quick-disconnect utility hookups.

Sources & Official References

[1]Longmont Municipal Code, Title 20 - Floodplain Management

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All Longmont rules

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Significant Restrictions