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This layer shows the Federal Emergency Management Agency (FEMA) floodplain boundaries for Newton. These are the boundaries as they appear on FEMA’s Flood Insurance Rate Maps (FIRM). The FEMA maps were compiled at a much smaller scale and therefore are considerably less accurate than Newton’s Floodplains data layer.

Newton’s Floodplains layer shows actual floodplains as designated by city Engineers. This layer refers to legal areas defined by FEMA for flood insurance requirements and rates.

Features and Attributes

For full documentation visit FEMA online. The “zone” polygon attribute classifies all of Newton into one of three areas: Zone AE, Zone X, and Zone X*. Zone AE is defined as, “An area inundated by 1% annual chance flooding (usually sheet flow on sloping terrain), for which average flood depths and velocities have been determined; flood depths range from 1 to 3 feet”. Zone X* is defined as, “An area inundated by 0.2% chance flooding; an area inundated by 1% annual chance of flooding with average depths of less than 1 foot or with drainage areas less than 1 square mile”. The other Zone X* areas are uplands or areas that have not been studied.

*There are two zones marked Zone X on the current FEMA maps. Upland areas and the areas formerly known as Zone X500 is the area described above with the 0.2% chance of flooding.

Last Updated: March, 2023