Mitigation Zones - Metro Flood Diversion Authority

The Upstream Mitigation Area or UMA means the area where the member entities of the MFDA are required to obtain property rights as mitigation for the temporary storage of floodwaters during Project operations.
The UMA is defined using four mitigation zones, summarized as follows.

Mitigation Zone Definitions
Zone 1	Depth difference of 1-foot or greater for the 100-year and 500-year flood events (whichever is greater) within Cass and Clay Counties and along the Red River corridor within Richland and Wilkin Counties.
Zone 2	Depth difference of 1 foot or greater for the 100-year and 500-year flood events (whichever is greater) within Richland and Wilkin Counties.
Zone 3	This is an area in North Dakota beyond Federal Mitigation Zone 1 and Zone 2 where the Project causes a hydraulic effect of 0.5-feet or more at the 100-year flood event.
Zone 4	This is an area in Minnesota beyond Federal Mitigation Zone 1 and Zone 2 where the Project causes a hydraulic effect of 0.1-feet or more from flood events up to and including the Probable Maximum Flood (PMF) flood event. Mitigation Zone 4 is divided into three sub-zones reflecting the flood event that defines the boundary of impacts.
Zone 4A	This is an area in Minnesota beyond Federal Mitigation Zone 1 and Zone 2 where the Project causes a hydraulic effect of 0.1-feet or more at the Probable Maximum Flood PMF event.
Zone 4B	This is an area in Minnesota beyond Federal Mitigation Zone 1 and Zone 2 where the Project causes a hydraulic effect of 0.1-feet or more at the 500-year flood event.
Zone 4C	This is an area in Minnesota beyond Federal Mitigation Zone 1 and Zone 2 where the Project causes a hydraulic effect of 0.1-feet or more at the 100-year flood event.

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