Revisions or updates to the specific maps and data that alter the established floodplains or floodway of the regulated flood hazard area require DNRC approval pursuant to Montana Code Annotated 75-5-203. An alteration of the regulated flood hazard area is a DNRC approved amendment to the DNRC order that originally delineated and designated the 100-year floodplain and is the basis of the regulated flood hazard area referenced in section 14-3-2 of this chapter. A DNRC approved alteration consists of revisions or updates to the specific maps and data of the referenced studies of this title and forms the basis for an amendment to the regulated flood hazard area. Any change to the regulated flood hazard area as a result of a DNRC alteration is effective upon amendment to the regulated flood hazard area described in section 14-3-2 of this chapter.
Substantial natural physical change or new technical or scientific flood data showing that the base flood elevation has or may be changed or was erroneously established shall be brought to the attention of DNRC and FEMA. Any floodplain permit application for a proposed development or artificial obstruction must be denied until a DNRC alteration pursuant to Montana Code Annotated 76-5-203, is approved if it causes an increase of 0.5 foot or more to the base flood elevation of a regulated flood hazard area without a floodway or an increase of more than 0.00 feet to the base flood elevation of a floodway.
To propose an alteration a petition must be submitted to DNRC and must include the following information:
A. Certification that no buildings are located in the areas which would be impacted by the increased base flood elevation;
B. Evidence of notice to all property and land owners of the proposed impacts to their properties explaining the proposed impact on their property;
C. Information that demonstrates that alternatives are not feasible;
D. Information that demonstrates that development is for a public use or benefit; and
E. Any other supporting information and data as needed for approvals.
The floodplain administrator may represent the permit authority for any necessary applications, approvals or endorsements such as the FEMA community acknowledgement form to FEMA where affecting the FEMA special flood hazard area.
A determination by the floodplain administrator that land areas located within the regulated flood hazard area are above the base flood elevation as proven by a certified elevation survey does not constitute or require an alteration or an amendment of the regulated flood hazard area and may be maintained as a public record that more explicitly defines the regulated flood hazard area boundary. Elevating with suitable fill as permitted does not alter the regulated flood hazard area or remove the elevated area from the regulated flood hazard area. A floodplain permit implementing the physical change cannot be approved until a CLOMR has been issued by FEMA. (Ord. 15-16, 10-5-2015)