City of Ann ArborThat portion of the river valley, adjacent to the channel, which is built of sediments deposited during the present geological / climatic regime. Based on statistically derived hydrologic recurrence intervals, a portion of the land adjacent to the watercourse experiences bank full overflow during flood stage episodes. Source is FEMA FIRM Mapping.floodplainengAnn Arbor Data CatalogPublicEnvironmentFloodplainDatasetsMichigan--Ann ArborMichiganLast Modified: 2026-05-10