Flood Zones in Butler County, Iowa: What the 2016 Flood Means for Land Here

September 2016: a new record crest, and a levee that failed overnight

More than 12 inches of rain fell across northeast Iowa, southeast Minnesota, and southwest Wisconsin in a 24-hour period on September 22-23, 2016, sending the Shell Rock River to a record crest of 21.51 feet at the city of Shell Rock on September 23 -- surpassing the river's previous record of 20.36 feet, set on June 10, 2008, during the broader 2008 Iowa flood. In Clarksville, a temporary levee protecting the town gave way overnight on September 22, and the river's rise forced more than 280 of the community's roughly 1,400 residents from their homes on short notice, including about three dozen residents evacuated from the Westside Assisted Living facility as a precaution (the facility itself stayed dry). The scale of the emergency response reflects how serious the event was: crews and volunteers placed an estimated 180,000 sandbags and 4,300 linear feet of flood barriers, delivered with support from the Iowa Department of Homeland Security and Emergency Management.

Governor Terry Branstad issued a state disaster proclamation specifically naming Butler, Chickasaw, and Floyd Counties in response to this event, covering the string of Shell Rock and Cedar River valley communities hit by the flooding -- Shell Rock, Clarksville, Greene, and Nashua in Butler and neighboring counties, along with Nora Springs and Charles City further downstream. This was one wave in a broader run of Iowa flooding across September and October 2016 that led to additional, wider federal disaster-declaration activity across the state; we could not confirm the specific FEMA major-disaster-declaration number covering Butler County for this event in this research pass, so treat the governor's proclamation -- which is well documented and specifically names Butler County -- as the confirmed anchor fact, and verify any federal declaration number directly with FEMA or Iowa Homeland Security and Emergency Management if it matters for a specific claim or program.

What's unconfirmed: permanent levee status and current FIRM revisions

We could not confirm, in this research pass, whether Clarksville has since built a permanent levee or flood-control structure to replace the temporary levee that failed in 2016, whether a FEMA-funded property buyout program was carried out for flood-damaged Clarksville properties (as happened in some other Iowa flood-hit communities), or whether Butler County's effective FEMA Flood Insurance Rate Map (FIRM) panels along the Shell Rock River corridor have been revised since 2016. Don't assume any of these things happened, and don't assume none of them did -- confirm current levee infrastructure, floodplain map status, and any buyout-eligible areas directly with the Butler County Zoning Office and, for anything inside city limits, the City of Clarksville, before relying on this page as the final word on current flood protection.

What this means for evaluating land near the Shell Rock River

If you're evaluating a parcel near the Shell Rock River anywhere in Butler County -- particularly near Shell Rock or Clarksville -- treat the September 2016 event as the flood to benchmark against rather than an older or more theoretical FIRM scenario: a record crest that broke an 8-year-old record, paired with an actual levee failure that displaced a fifth of a town's population overnight, shows the river can exceed both historical expectations and existing flood-control infrastructure. Ask the county for the parcel's current FIRM zone, ask specifically whether the levee or floodplain protection near a given parcel was upgraded after 2016, and ask whether the parcel or any structure on it was affected by the 2016 flood before treating flood risk along this corridor as settled or fully mapped.