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FEMA FLOOD ZONE DESIGNATIONS & EXPLANATIONS |
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Annual Probability of Flooding of 1% or greater |
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A |
Subject to 100-year flood. Base flood elevation undetermined. |
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AE or A1-A30 |
Both AE and A1-A30 represent areas subject to 100-year flood with base flood elevation determined. |
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AH |
Subject to 100-year shallow flooding (usually areas of poundings) with average depth of 1-3 feet. Base flood elevation determined. |
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AO |
Subject to 100-year shallow flooding (usually sheet flow on sloping terrain) with average depth of 1-3 feet. Base flood elevation undetermined. |
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A99 |
Subject to 100-year flood, with federal flood protection system (levee/dam) under construction. Base flood elevation undetermined. |
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V |
Subject to 100-year flood and additional velocity hazard (wave action). Base flood elevation undetermined. |
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VE or V1-V30 |
Both VE and V1-V30 represent areas subject to 100-year flood and additional velocity hazard (wave action). Base flood elevation determined. |
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In SFHA |
Areas in a "Special Flood Hazard Area" (or 100-year flood plain). Subject to 1% annual chance flooding. No distinctions have been made between the different flood hazard zones that may be included within the SFHA. |
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Flood Prone Area |
An area designated as a "Flood Prone Area" on a map prepared by USGS and the Federal Insurance Administration. This area has been delineated based on available information on past floods. This is an area inundated by 1% annual chance flooding for which no base flood elevations have been determined. |
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Annual Probability of Flooding of 0.2% to 1% |
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B or X500 |
Both B and X500 represent areas between the limits of the 100-year and 500-year flood; or certain areas subject to 100-year flood with average depths less than 1 foot or where the contributing drainage area is less than 1 square mile; or areas protected by levees from the 100-year flood. |
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Annual Probability of Flooding of Less than 0.2% |
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C or X |
Both C and X represent areas outside the 500-year flood plain with less than 0.2% annual probability of flooding. |
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Annual Probability of Flooding of Less than 1% |
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No SFHA |
Areas outside a "Special Flood Hazard Area" (or 100-year flood plain). Can include areas inundated by 0.2% annual chance flooding; areas inundated by 1% annual chance flooding with average depths of less than 1 foot or with drainage areas less than 1 square mile; areas protected by levees from 1% annual chance flooding; or areas outside the 1% and 0.2% annual chance floodplains. |
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Undetermined |
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D |
Unstudied areas. Flood hazards are undetermined. |