The 1972 Black Hills/Rapid City Flood

The Damage from the 1972 Flood. June 2007 marks the 35th anniversary of the worst flood in the recorded history of the Black Hills. Heavy rains-from 10-15 inches in six hours in some areas-produced floods that killed 238 people and injured an additional 3,057 people, according to a U. S. Geological Survey (U.S.G.S.) fact sheet produced in 2002. Property damage was estimated to be in excess of $160 million (equivalent to $600-700 million in today's dollars), and the flood destroyed 1,335 homes and 5,000 automobiles, according to the report. Photographs taken after the flood show automobiles stacked on top of one another.

Conditions for Flooding. Heavy rains fell on June 9-10, but prior to that, showers throughout the Black Hills area had saturated the ground, leaving the Black Hills ripe for a catastrophe. Increased rain leading to increased soil saturation led to increased runoff which led in the end to the disastrous flooding. Atmospheric conditions created a series of severe thunderstorms. Combined with the thunderstorms were light winds, which meant that the storms did not move; instead, they dumped heavy rains in a limited area. According to a 1972 report from the National Oceanic and Atmospheric Administration, quoted by the U.S.G.S., "The heaviest rainfall averaged about four times the 6-hour amounts that are to be expected once every 100 years in the area."

The result was record flooding. Fortunately, the flooding did not last long. In the Rapid City area, one creek-the Rapid Creek-was back to its normal level by the evening of June 10.