La Plata County, CO Environmental Rules: Flood Elevation Requirements (2026)

Section 78-73 of the La Plata County Code sets the elevation rules for all special flood hazard areas except the shallow flooding areas covered by section 78-75, and it directs that available base flood elevation data be used to decide compliance. For a residential structure, one foot of freeboard above the base flood elevation applies to the lowest floor, the basement, and the electrical, heating, ventilation, plumbing and air conditioning equipment and other service facilities, ductwork included. When the structure is finished, a registered Colorado Professional Engineer, architect or land surveyor certifies the lowest-floor elevation, and the certification goes to the floodplain administrator, who is the manager of the county building department.

Nonresidential buildings have a choice. They can meet the same one-foot elevation, or be flood proofed so the structure is watertight, with substantially impermeable walls, to at least one foot above the base flood elevation. A Colorado registered professional engineer or architect must develop or review the design and certify it, and the floodplain administrator keeps the certification. Critical facilities follow section 78-79 instead.

Fully enclosed areas below the lowest floor that are used solely for parking, building access or storage need at least two openings with a total net area of not less than one square inch for every square foot of enclosed area, and the bottom of every opening can be no higher than one foot above grade. Manufactured homes in Zones A1-30, AH and AE go on a permanent foundation with the lowest floor and equipment at least one foot above base flood elevation. In existing manufactured home parks the alternative is a chassis supported by reinforced piers at least 36 inches above grade. Recreational vehicles must be on site fewer than 90 consecutive days, be fully licensed and ready for highway use, or meet the permit, elevation and anchoring rules. A below-grade crawlspace cannot exceed four feet in height, and its interior grade can be no lower than two feet below the lowest adjacent grade.

In shallow flooding areas (AO and AH zones), section 78-75 requires the lowest floor of a residential structure to sit above the highest adjacent grade at least one foot above the depth number on the FIRM, or at least three feet if no depth number is specified.