Changes that took effect earlier this month could save thousands of Camden County landowners over $3 million annually in federal flood plain insurance.

Changes that took effect earlier this month could save thousands of Camden County landowners over $3 million annually in federal flood plain insurance.

More than two years ago, the FEMA Region VII Office in Kansas City undertook a review of 2011-era FIRMs for the area utilizing a new method of hydrologic analysis approved by the U.S. Geological Survey in 2014. FIRM stands for Flood Insurance Rate Map. The outcome was a revision to the flood plain maps that included some areas in Camden, as well as a few in Miller and Morgan counties. The changes took effect on April 18.

Camden County Planning and Zoning Administrator Tanna Wirtz said she has had quite a few calls in the last several weeks from landowners trying to determine if their property is included in the revisions. Wirtz recommends landowners visit the FEMA website and look at the map service information to determine if they fall within the revised areas.

According to officials, the areas in Camden County that are most affected by the revised maps include portions of the Big Niangua, Little Niangua and Linn Creek.

Estimates given early on in the process by Camden County officials indicated the map revisions had an impact on 3,840 parcels of land and represented an annual savings on flood plain insurance of $3.5 million annually.

BACKGROUND:

More than two years ago, the FEMA Region VII Office in Kansas City undertook a review of 2011-era FIRMs for the area utilizing a new method of hydrologic analysis approved by the U.S. Geological Survey in 2014. FIRM stands for Flood Insurance Rate Map.

According to officials, the areas in Camden County that are most affected by the revised maps include portions of the Big Niangua, Little Niangua and Linn Creek. Nine panels in Camden County were updated, while two each were updated in Morgan and Miller counties.

During a preliminary review of the proposed revised FIRMs in June 2016, the overall outcome of the review appeared to be good news with the amount of high hazard flood area generally less than the current area due to the base flood elevation (BFE) along some of the main tributaries of the Lake of the Ozarks being lowered.

With the new methodology, estimated flood flow was reduced dramatically - some by as much as half, according to FEMA Region VII Risk Analysis Branch Chief Rich Leonard - on the Niangua River, Little Niangua and Grand Glaize. That in turn impacted the hydraulic analysis used to set the BFE.

Hydraulic analyses take into account flood flow combined with the topography or geometry of the stream channel at various cross sections.

For the Niangua River, the BFE would be lowered as much as four to five feet. Linn Creek and Gravois Creek were two areas where the flood flow estimates actually increased, thereby raising the proposed BFE. For Linn Creek the difference amounted to approximately half of a foot, while Gravois Creek would see a range from just under a foot in places up to four feet higher further upstream.