Know your Flood Hazard

Know your Flood Hazard

Floodplains in unincorporated Story County were first mapped in November 1977, and the initial Flood Insurance Rate Map (FIRM) became effective June 1, 1983. Over 95,000 acres are mapped in the unincorporated areas of Story County by FEMA as Special Flood Hazard Areas, and only 12% of those mapped areas are in areas with detailed flood studies.

The local streams and rivers in Story County include: Ballard Creek, Clear Creek, College Creek, Fourmile Creek, Indian Creek, Keigley Creek, Long Dick Creek, Onion Creek, Rock Creek, Rock Creek Tributary, Skunk River, South Skunk River, Squaw Creek, Walnut Creek, West Branch Indian Creek, Worle Creek, and various unnamed creeks and tributaries. Over 90 percent of Story County lies in the upper reaches of the Skunk River basin whose drainage eventually outlets to the Mississippi River. Development in the county is sparse residential. Development in the floodplain is primarily agricultural in nature, with areas of single-family residential and limited commercial.

The history of flooding of the streams in Story County indicates that flooding usually occurs during the spring and summer months of the year. The area is particularly susceptible to flooding caused by a combination of rainfall and snowmelt.

How to get more information?

Information on whether your property is in the floodplain can be obtained by visiting Story County and having our Certified Floodplain Manager (CFM) help you. Maps are available for viewing in the office of the County Outreach and Special Projects Manager (in the Story County Administration Building) and also available (in general format) on the Story County Assessor's website.

Other flood-related information is also available both at the County and on the website. We also have Elevation Certificates available for new development (for the unincorporated areas of Story County) and older Flood Insurance Rate Maps (FIRMs) from 1983.

For more information, please review our "Mapping" page and contact us at 515-382-7247 or email the Floodplain Manager with any additional questions you may have.

Resources and Publications

Public Service Notice - Map Information Service (PDF)
Changes in Flood Maps (PDF) (FEMA-developed)

You can find more information on the FloodSmart website, the official site of the National Flood Insurance Program.