Floods, in Colorado's semi-arid climate?  You bet.  Fort Collins residents can testify to the inundation that occurred from more than fourteen inches of rain being dumped on their city in thirty-one hours in 1997.  That is the amount typically received in a whole year.  Floods perennially threaten much of the state because of the high topographic relief of the drainage basins, torrential spring thaws, and intense summer thunderstorms. Early pioneers often chose to build highways, railroads, and towns in canyons close to riverbanks.  Predictably, flooding was among the first natural hazards of which new citizens became painfully aware.  Large floods devastated Denver, Pueblo, and other Colorado cities.
 
Colorado's most expensive flood was probably the "Flood of 1965" in the South Platte River Basin south of Denver.  This flood caused $508 million worth of damage and drowned six people. The losses can be attributed to the failure to realize the significance of the South Platte drainage routes and flood plains.  Homes, shopping centers, and many other buildings occupied-and still occupy-land that has been intermittently flooded for many years.