Residents of northern Michigan faced unprecedented flooding this spring, revealing significant gaps in the region’s flood risk mapping and insurance coverage. The historic flooding, which overwhelmed homes, damaged infrastructure, and prompted states of emergency across dozens of counties, highlighted long-standing limitations in how flood risks are assessed and managed in less-populated areas.

Tom and Diane Peterman, who bought a retirement home on Black Lake 14 years ago, were unable to secure flood insurance at the time, while John Solum, a cabin owner on the same lake, was assured his property was outside flood zones. Both households experienced severe damage this spring, with floodwaters damaging floors, walls, furniture, and appliances. The lake’s water levels rose so dramatically that floating ice broke decks and crashed through windows.

Across Michigan, communities were unprepared for the combined impact of record snowfall in March and heavy rainfall in April. Despite growing evidence of increased precipitation intensities linked to climate change, many residents were unaware of their exposure to flooding, largely due to outdated and incomplete flood plain maps.

Flood risk maps maintained by the Federal Emergency Management Agency (FEMA) play a dual role in determining insurance requirements and helping local planning efforts. However, FEMA has not systematically developed flood maps for many less-populated areas, including parts of Michigan where Black Lake is situated. The lake spans two counties—Cheboygan, with a flood map last updated in 2012, and Presque Isle, where much of the area has never been mapped.

Moreover, FEMA’s flood mapping primarily addresses risks from rivers and streams overflowing their banks, overlooking flooding caused by intense rainfall that can overwhelm stormwater systems or inundate rural areas. First Street, a firm specializing in climate-related financial risk analysis, incorporated comprehensive rainfall data and smaller waterways into its models and found more than twice as many properties nationwide at significant flood risk compared to FEMA’s maps. In Michigan, the number of properties identified at risk was four times higher.

Jeremy Porter, chief economist at First Street, emphasized that federal maps are “missing a whole source of flooding” by not fully accounting for heavy rainfall events in their risk assessments. While FEMA reportedly uses rainfall data in setting insurance rates, it remains unclear whether this information is integrated into flood plain mapping efforts.

Five years ago, the Government Accountability Office cautioned that FEMA’s flood hazard maps did not incorporate the latest climate science or adequately reflect heavy rainfall patterns. FEMA declined interview requests for further comment but stated that 95% of the U.S. population resides in areas with maps that represent “snapshots in time.” The agency did not address whether this year’s flooding will accelerate updates to mapping in rural or less-mapped regions.

Michigan’s National Flood Insurance Program coordinator, Matthew Occhipinti, called the spring floods “truly a monumental flood,” exceeding the 100-year flood threshold—an event with a 1% chance of happening annually—in many areas. Scientists link these extreme events to a warming atmosphere capable of holding more moisture, which can result in heavier precipitation. University of Michigan climate scientist Richard Rood noted that an “extraordinarily warm” Gulf of Mexico contributed to both heavy snow and rain in the region this spring, intensifying the flooding crisis.