In June 1965, several days of extraordinarily heavy rains in the Denver area resulted in massive flooding along the South Platte River. Hundreds of homes and businesses were completely destroyed as were most of Denver's bridges over the river. In all, the damages exceed $500 million dollars. Butch La Rita was there and gives us a graphic first-hand account of the devastion that was left in the flood's wake.
Casualty counts vary, depending on the source. In a 1999 article, the Rocky Mountain News reported that the flood took six lives, while a 2007 article in the Denver Post attributed "more than two dozen" deaths to the flood. Wikipedia puts the total at 28.
Following the destruction, the South Platte River was dammed to help prevent future floods. The project, completed in 1975, resulted in Chatfield Lake in southwest Denver, part of Chatfield State Park.
The images below appear courtesy of the Denver Public Library.