Floodplains – What are the Zones?
Floodwaters don’t stop at a line on a map. In fact, more than 20% of National Flood Insurance Program (NFIP) claims come from areas outside of mapped high-risk flood zones. And just a few inches of floodwater can cause tens of thousands of dollars in damage to your home and its contents.
(Special Flood Hazard Area or SFHA)
In high-risk areas, there is at least a 1 in 4 chance of flooding during a 30-year mortgage. More commonly known as the 100-Year Floodplain.
All home and business owners in these areas with mortgages from federally regulated or insured lenders are required to buy flood insurance. Flood insurance is mandatory. Flood insurance is federally required for most mortgage holders. Insurance costs may rise to reflect the true (or high) risk.
Within the High Risk Zones you have the following here in Lincoln County:
- Approximate A: Areas with a 1% annual chance of flooding and a 26% chance of flooding over the life of a 30‐year mortgage. Because detailed analyses are not performed for such areas; no depths or base flood elevations are shown within these zones. You will have to determine the elevation for any development.
- AE: The base floodplain where base flood elevations (BFE) are provided. AE Zones are now used on new format FIRMs instead of A1‐A30 Zones. When developing; these elevations are your base start and any flood needs to be two (2) feet above this elevation to alleviate any insurance or permitting issues.
- AO: River or stream flood hazard areas, and areas with a 1% or greater chance of shallow flooding each year, usually in the form of sheet flow, with an average depth ranging from 1 to 3 feet. These areas have a 26% chance of flooding over the life of a 30‐year mortgage. Average flood depths derived from detailed analyses are shown within these zones. Hardest to remove from the floodplain.
Moderate- to Low-Risk Areas
(Non-special Flood Hazard Area or NSFHA)
In moderate- to low-risk areas, the risk of flooding is reduced but not completely removed. More commonly known as the 500-Year Floodplain.
These areas submit more than 20% of NFIP claims and receive one-third of Federal disaster assistance for flooding. Flood insurance isn’t federally required in moderate- to low-risk areas, but it is recommended for all property owners and renters. Flood insurance is optional but still recommended. The risk is only reduced, not removed. You can still obtain flood insurance, and at a lower rate. Even though flood insurance isn’t federally required, everyone is financially vulnerable to floods.
Within the Moderate-to-Low Risk Zones you have the following here in Lincoln County:
- Shaded X (or B Zone): Area of moderate flood hazard, usually the area between the limits of the 100‐ year and 500‐year floods. B Zones are also used to designate base floodplains of lesser hazards, such as areas protected by levees from 100‐year flood, or shallow flooding areas with average depths of less than one foot or drainage areas less than 1 square mile.
- Unshaded X (or C Zone): Area of minimal flood hazard, usually depicted on FIRMs as above the 500‐year flood level. Zone C may have ponding and local drainage problems that don’t warrant a detailed study or designation as base floodplain. Zone X is the area determined to be outside the 500‐year flood and protected by levee from 100‐ year flood.
ZONE D: Undetermined Risk Areas
Some flood maps also include areas where there are possible but undetermined flood hazards or unstudied areas. Flood insurance rates reflect the uncertainty of the flood risk. This is less than 1% of Lincoln County.