1972 Black Hills flood

15 inches (380 mm) of rain in a small area over the Black Hills caused Rapid Creek and other waterways to overflow.

Severe flooding of residential and commercial properties in Rapid City occurred when Canyon Lake Dam became clogged with debris and failed in the late evening hours of June 9 resulting in 238 deaths and 3,057 injuries.

"[4] On the afternoon of June 9, substantial rains fell on the area, caused by "an almost stationary group of thunderstorms.

"[4] Additionally, "a strong low-level easterly flow which forced the moist unstable air up-slope on the hills.

This sustained orographic effect helped the air to rise, cool, and release its moisture in repeating thunderstorms.

Another contributing factor was the unusually light winds at a higher atmospheric levels which did not disperse the moist air nor move the thunderstorms along to prevent an extreme concentration of rainfall.

"[4] According to Herbert Thompson the air pattern causing this storm was noticed in big measure over the Great Plains, with a minor scale to the east of the Rockies.

The run-off carried rubble to the Canyon Lake Dam creating a barrier in front of its spillway.

Flood waters displaced large rocks, trees, trailers, and vehicles, and carried homes away.

The total amount of rain the Black Hills received was "800,000 acre feet" equal to "1 billion metric tons of water.

In 1972, the National Weather Service office in Rapid City did not have a teletype system to broadcast warnings.

Today warnings are sent to a regional site where they are sent to the National Oceanic and Atmospheric Administration (NOAA) Weather Wire System satellite.

The majority of the flood plain was made into large parks, which have increased in number and have been improved and updated on a continuing basis.

For those who have given up all hope about finding a priceless photo album or sheet of important personal papers there may be a happy ending with "Operation Family Treasure," a clearing house for irreplaceable items run by the Rapid City Jaycees in conjunction with the Office of Civil defense.

Rita, who was 20 at the time, described the scene, "There was so many [people] in trees and screaming and crying and the sparks were flying from electric wires, houses were on fire, it was just — it was hell," she says.

We grabbed the children and my dad's crippled and we picked him up and put him in the car, and just as we drove out the driveway, a big trailer started floating right across the pathway, and we just made it up the hill and that was all it was.