image of Flood Plain

The purpose of a Floodplain Delineation Study is to establish the limits of the Floodplain District within or near proposed construction activity or development when an acceptable delineation does not already exist, or when proposed development may change an existing delineation.

A Floodplain District is defined as the area subject to inundation in a 100-year storm from a drainage area of 30 acres or more, plus a 25-foot buffer. Because the inundated area is dependent on topography and existing features it often traverses property lines.

Any land disturbing activity (which may include temporary or permanent construction) within a Floodplain District may require a Floodplain District Permit. In some instances, the limits have already been established by methods acceptable to DPS. However, when that is not the case, a Floodplain Delineation Study must be performed. Once the 100-year floodplain is delineated by a study for the existing condition, a Floodplain Delineation Study for the proposed development condition may also be required.