Flood Zones in Wapello County, Iowa

Two floods, both well past ordinary flood stage, sixty years apart

The Des Moines River's flood record through Wapello County is unusually well documented for two twentieth-century events. In 1947, the entire population of Eddyville -- a town on the river upriver from Ottumwa -- evacuated before floodwaters submerged the town entirely; downriver in Ottumwa, residents banded together to build emergency dikes and stack sandbags, while the U.S. Army sent food and supplies to stockpile at local schools as river levels exceeded 20 feet. According to local historical accounts, the river did not exceed that 20-foot threshold again for decades -- until the flood of July 1993, which set the all-time record crest for the Des Moines River at this location: 22.15 feet, recorded on July 12, 1993.

That means two of the most severe flood events recorded on this stretch of the Des Moines River -- a full-town evacuation in 1947 and an all-time record crest in 1993 -- occurred on the same river reach that runs through populated parts of Wapello County. For context, USGS maintains long-running stream gauges on the Des Moines River both at Ottumwa and further upriver at Eddyville, providing continuous historical discharge and stage data for anyone researching a specific parcel's flood exposure along this corridor.

What the record crest means for floodplain mapping today

A record crest that high, on a river that has now cleared 20 feet in at least two separate historical events, is the kind of data point that legitimately shapes FEMA's Flood Insurance Rate Map (FIRM) boundaries for the area -- mapped Special Flood Hazard Areas along this stretch of the Des Moines River are not a theoretical worst-case exercise but a reflection of documented past events. Iowa DNR regulates construction within mapped floodplains statewide, and a floodplain development permit, with DNR approval, is required before construction begins on any property within a mapped 100-year flood zone. The DNR's online PERMT system handles the state-level floodplain permit application, but it explicitly does not submit applications to county or city officials for local floodplain permitting -- so any locally required floodplain permit is a separate step you have to take up with the county directly.

For a buyer, the practical sequence is: pull the current FEMA FIRM for the specific parcel (not a general county-level flood statement) to determine whether it falls within a mapped Special Flood Hazard Area; check the Iowa Flood Center's flood-risk mapping tools, which draw on more granular Iowa-specific flood modeling than the national FEMA maps alone; and confirm with Wapello County Planning and Zoning whether the parcel would require a local floodplain development permit for any construction, addition, or substantial improvement. Given the documented severity of the 1947 and 1993 events on this river reach, do not assume that a parcel's apparent distance from the current riverbank at normal flow is a reliable substitute for an actual flood-zone determination -- the 1993 crest reached levels that put river water well beyond the channel itself.

What to verify before buying

• The parcel's current FEMA Flood Insurance Rate Map (FIRM) zone designation, pulled for the specific parcel rather than assumed from a general county flood history.
• Whether the parcel would require a Wapello County floodplain development permit for any proposed construction, addition, or substantial improvement, separate from the state-level DNR permit.
• Historical high-water marks near the specific parcel if available, given the documented 1993 record crest (22.15 feet) and the 1947 flood's severity at Eddyville.
• Whether flood insurance is required as a condition of any mortgage financing for the parcel, and current NFIP premium costs for the mapped zone.