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Updating Charlotte-Mecklenburg Floodplain Maps

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. Additional information below explains the purpose of floodplain maps and the reason maps are being updated.

Draft Phase 3 floodplain maps now available
Phase 3 covers Charlotte-Mecklenburg's northeastern watersheds - the areas shown in yellow on the map below. New floodplain maps for these watersheds are now available in draft form.

See the Phase 3 draft floodplain maps

You may review the maps online. From August ​30 through October 18, 2014, the mapping application allows you to enter comments or ask questions online.

Public meetings about the draft Phase 3 floodplain maps for northeastern Charlotte-Mecklenburg were held in September.
People attending a floodplain mapping meeting
           Public meetings are part of the
                  remapping process

Frequently asked questions about updating floodplain maps


Five-step process
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:

• Planning
• Development
• Draft
• Preliminary
• Effective

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 are being revised again in 2014.

Phase 2 – Western Charlotte-Mecklenburg (shown on map below in green)
Now in Preliminary status – one step away from becoming effective. Expected to become effective in 2015.

Phase 3 – Northeast Charlotte-Mecklenburg (shown on map below in yellow)
Now in Draft status – available for public review and comment

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​​​​​​​​​​​​​​​​

Phase 1 - Effective

Phase 1 includes the area shown in tan on the map, mostly central and southeastern Charlotte-Mecklenburg.

 

New floodplain maps for Phase 1


Updated floodplain maps for Phase 1 became effective on February 19, 2014.

 

Effective maps are considered official for both flood insurance and for local building regulations (development).


New floodplain maps for Little Hope Creek are undergoing an additional revision. The corrected Little Hope Creek maps will likely take effect in the fall of 2014.

Floodplain regulations for Charlotte, Matthews, Mint Hill and Pineville have been updated to reflect both the new flood hazard data and the date the new floodplain maps take effect.​

​​

Phase 2 - Preliminary


Phase 2 covers the western watersheds, shown on the map above in green. Please note that Phase 2 floodplain remapping includes parts of the Catawba River but does not include most lakefront property along Lake Norman or Lake Wylie.

Preliminary floodplain maps for Phase 2

Updated floodplain maps for Phase 2 became Preliminary on February 5, 2014. This means the new maps can be used for some building regulations. But during the Preliminary stage, the new floodplain maps are not used for flood insurance purposes.

Public meetings were held in April 2014 to show the Phase 2 preliminary maps to the public and get input. The next step is FEMA's mandatory, year-long review. 

The new Phase 2 floodplain maps are expected to become effective in 2015.


Phase 3 - Draft


Northeast Mecklenburg watersheds, shown on the map above in yellow, are the third phase of Charlotte-Mecklenburg’s floodplain remapping effort. Draft versions of these floodplain maps are now available. More information is at the top of this page.

Draft floodplain maps for Phase 3

After the public meetings and the required local and federal reviews, new floodplain maps for Phase 3 are expected to become effective in 2016.


Phase 4 - Planning

The final remapping phase of local floodplains will be along Lake Norman and Lake Wylie. No engineering work has begun yet for Phase 4.​


What are floodplain maps?

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.

Floodplain map using colors to show floodwater depth​​
 
Why do floodplain maps change?
 
Flood risks change because of:
  • development
  • population changes
  • local projects to manage storm water

Mapping technology has improved since the last remapping more than ten years ago. New technology allows Storm Water Services to more accurately predict where floodwater is likely to flow. The new maps also calculate how deep floodwater is likely to get. And they show how frequently a section of land is expected to flood.  

 
 
 
 
 
  
 
For more information about floodplain map updates:
 
Floodplain Administrator
Charlotte-Mecklenburg Storm Water Services
704-336-3734