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The Department of Commerce, Community, and Economic Development offices are closed to the public at this time. We are still open for business and encourage you to contact us via phone or email.

Local Government Resource Desk

Planning & Land Use

Floodplain Management


A "floodplain" is the lowland adjacent to a river, lake, or ocean. Floodplains are designated by the frequency of the flood that is large enough to cover them. For example, the 10-year floodplain will be covered by the flood having a 1 in 10 chance of occurring annually. The 100-year floodplain is more commonly referred to as the one-percent flood or a flood having a one percent chance of occurring annually.

Flood frequencies, such as the one-percent flood (100-year flood), are determined by plotting a graph of the size of all known floods for an area and determining how often floods of a particular size occur.

Narrative Frequently Asked Questions Additional Resources Applicable Laws and Regulations

Revised 12/18/2014