Storm Water Services is updating local floodplain maps. The process takes several years. For remapping, Mecklenburg County has been divided into four geographical areas called “phases.” New floodplain maps are being developed and adopted starting with Phase 1 and ending with Phase 4. The map below shows the four phases.
Floodplain maps show how likely it is for a building or a section of land to be affected by rising water from a creek during a storm event. Flood risks change over time. Floodplain maps must be updated to accurately show that risk.
The main uses of floodplain maps are:
• Flood insurance – which buildings must have it and how much it costs
• Local building regulation – grading, building and remodeling in the mapped floodplain must comply with special rules and regulations.
Drawing new floodplain lines does not have the same effect on all properties. In some cases, floodplain areas and the expected depth of flood water (called “elevation”) are expanding. So some properties that have been outside of the floodplain on the old maps will be inside the floodplain on the new maps. In other locations, floodplain areas and elevations are getting smaller. That means some properties will be removed from the regulated floodplain on the new maps. And other properties are not affected by the remapping.
Frequently Asked Questions about updating floodplain maps
The remapping of Charlotte-Mecklenburg’s regulated floodplains follows the standards, methods and sequence of steps required by the Federal Emergency Management Agency (FEMA). The sequence is:
FEMA sets the dates that the maps enter the Preliminary and Effective stages. Once the Preliminary date is reached, higher Base Flood Elevations (if any) can be used for local building regulation. On the Effective date, the revised maps must be used for flood insurance purposes. The time between the Preliminary and Effective dates is usually 12 to 18 months.
Phase 1 – South-central and southeast Charlotte-Mecklenburg (shown on map below in tan
Took effect on February 19, 2014. The new floodplain maps are now official. They are being used for both flood
insurance and building regulation purposes. However, new maps for Little Hope Creek will be revised again in 2014.
Phase 2 – Western Charlotte-Mecklenburg (shown on map below in green)
Now Preliminary status – one step away from becoming effective.
Phase 3 – Northeast Charlotte-Mecklenburg (shown on map below in yellow)
Now in Development status – engineering work underway to draw new lines
Phase 4 – Lower Lake Wylie and all of Lake Norman (shown on map below in gray)
Now in Planning status – early stages of preparing to draw new lines
The where, when and what of new floodplain maps