Flash Flood — Delaware, Iowa

2010-07-24 · near Manchester Arpt, Delaware, Iowa

Event narrative

Record flooding on the Maquoketa River resulted in the failure of the earthen berm on the south side of the Lake Delhi/Hartwick Lake dam during the late morning and afternoon of July 24. The dam failure resulted in flash flooding of residences along the Maquoketa River immediately downstream of the dam, including portions of Hopkinton. In addition, the dam failure emptied out the 9 mile stretch of the Maquoketa River that constituted Lake Delhi/Hartwick Lake.

In Hopkinton, a few homes, several garages, outbuildings, parks and roads flooded.

By the time the flood waters reached Monticello, the flood wave from the dam failure had largely been absorbed in the larger crest due to the ongoing record flooding of the Maquoketa River.

Please see the Storm Data narrative for the record flooding on the Maquoketa River for details on the damage due to the flooded Maquoketa River, including the homes at Lake Delhi.

Wider weather episode

After repeated rounds of heavy rain associated with a stationary frontal boundary, record flooding on the Maquoketa River resulted in the failure of the earthen berm on the south side of the Lake Delhi/Hartwick Lake dam during the late morning and afternoon of July 24. The dam failure resulted in flash flooding of residences along the Maquoketa River immediately downstream of the dam. In addition, the dam failure emptied out the 9 mile stretch of the Maquoketa River that constituted Lake Delhi/Hartwick Lake.

View location on OpenStreetMap → (42.5000, -91.5000)

Source: NOAA Storm Events Database, event_id 250797. Narrative written by the NWS forecast office that issued the report.