FEMA flood map notices

Flood map changes in McHenry County, Illinois

FEMA has published 3 flood hazard notices covering McHenry County, Illinois since November 2023. The most recent, map revision flood hazard determinations, was published Mar 26, 2025.

Notices for McHenry County

Also covered by these notices

FEMA often studies whole watersheds, so one notice can span several counties.

What these notices mean

Proposed
FEMA has new draft flood maps. This starts a 90-day window when owners can appeal with technical data. It's the best time to act.
Final
Appeals are resolved. The new maps usually take effect about six months later, when lenders start applying the new zones.
Map revision
A Letter of Map Revision changes one stretch of the map, often after a levee, channel project or new survey.

Notices are organized by county and community, so a notice for your county doesn't mean your property is changing zones. What flood zones mean