Flash Flood in South Dakota, July 30, 2010

Name: Flash Flood in South Dakota, July 30, 2010
Start: 2010-07-30T00:00
End: 2010-07-30T06:00
Location: South Dakota

July 30, 2010 · NWS ABR · 1 event in 1 county or zone

Training thunderstorms across southeast Hand County brought very heavy rains of 5 to 10 inches which caused the Rosehill Dam to fail resulting in flash flooding.

Where it happened

Every event with a place to put it. Tap one for its entry below.

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The toll

Deaths: 0
Injuries: 2
Property damage: $150,000
Crop damage: None recorded
Events: 1

Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.

What happened

The episode as NWS ABR wrote it up.

Training thunderstorms across southeast Hand County brought very heavy rains of 5 to 10 inches which caused the Rosehill Dam to fail resulting in flash flooding.

What forecasters said that day

The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Aberdeen, SD wrote its last area forecast discussion before the first event at Jul 29, 8:52 PM CST, 3 hours 8 minutes earlier.

Area forecast discussion, Jul 29, 8:52 PM CST, 3 hours 8 minutes before

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Hazardous weather outlook, Jul 29, 4:17 AM CST, 19 hours 43 minutes before

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In the hours before

Local storm report, Jul 29, 8:37 PM CST, 3 hours 23 minutes before

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Local storm report, Jul 29, 8:58 PM CST, 3 hours 2 minutes before

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Local storm report, Jul 29, 9:00 PM CST, 3 hours before

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Local storm report, Jul 29, 9:15 PM CST, 2 hours 45 minutes before

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Local storm report, Jul 29, 10:26 PM CST, 1 hour 34 minutes before

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Local storm report, Jul 29, 11:22 PM CST, 38 minutes before

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The radar

The Aberdeen radar (KABR), 127 km away, was scanning. The volume nearest the first event began at 06:00 UTC.

Open the radar archive at this moment

Event by event

1 flash flood. Local standard time, as filed.

Flash Flood, Hand

When: July 30, 12:00 AM CST to 6:00 AM CST
Where: Hand County, 9.68 mi NE of Danforth to 10.45 mi NE of Danforth
Cause: Dam / Levee Break
Injuries: 2 direct, 0 indirect
Property damage: $150,000
Reported by: Emergency Manager
Coordinates: 44.340, -98.730

Very heavy rains of 5 to 10 inches caused the Rosehill Dam to break in the early morning hours in southeast Hand county. Flash flooding began around 1 am CDT with two campers being swept up around 130 am CDT. The two campers clung to a tree until they could be rescued around 6 am CDT. They were both injured with one camper being treated for hypothermia and other airlifted to Sioux Falls to be treated for broken ribs and head trauma.

The dam broke at 330 am CDT with the spillway breaking at 420 am CDT. There was a 100 to 150 foot hole left by the dam break. The flash flooding continued downstream on Sand Creek causing damage to area farms, filling basements, and flooding many roads.

What these are

Flash Flood: Flooding that begins within six hours of the rain that causes it, or of a dam or levee failure or ice jam release, often with deadly speed.

After NWS Directive 10-1605, the rules offices file Storm Data by.

The same day elsewhere

Every storm in South Dakota in 2010 Every state in 2010 This day in weather history Warnings in South Dakota, July 2010

Sources

NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-10-01. Each event’s entry at NCEI: 250759.