The Story
Thunderstorms stalled over the Black Hills and dropped up to 15 inches of rain in hours. Debris clogged Canyon Lake Dam's spillway until it breached around 10:45 p.m.; a crest of roughly 50,000 cubic feet per second tore through downtown by 12:15 a.m. on June 10. The flood killed 238 people, destroyed some 1,335 homes, and wrecked 15 of Rapid Creek's 23 bridges. Afterward the city permanently barred rebuilding across ~750 acres of floodplain, creating the greenway of parks and bike paths that runs through Rapid City today; Memorial Park downtown holds a monument naming the 238 victims.
Surprising Facts
→ The current dam is the third on the site (1890s resort dam, 1930s WPA rebuild, post-1972 reconstruction).
→ 15 of Rapid Creek's 23 bridges were destroyed and ~5,000 vehicles wrecked.
→ About 750 acres of floodplain were permanently rezoned to parks after 1972 — the greenway still used today.