The South Platte River flood of 1965 was one of the worst natural disaster in Denver’s history. It claimed twenty-one lives and resulted in property losses estimated at $543 million (more than $4.4 billion in 2019 dollars), with the worst damage occurring in the Denver metro area. While other Colorado floods have produced greater death tolls, including the Big Thompson Flood in 1976 and the Arkansas River Flood in 1921, the 1965 flood remains the most expensive flood in state history.
The flood ravaged hundreds of houses and all but obliterated dozens of businesses; many never recovered. It also led to a reappraisal of decades of haphazard urban growth and myopic planning. The disaster became a trigger for long-delayed flood control projects, ambitious urban renewal plans, and a renaissance along the South Platte itself.
Containing Cherry Creek
In 1858 gold prospectors, suppliers, and speculators set up a series of encampments near the confluence of the South Platte and Cherry Creek. What would become the city of Denver expanded in all directions from those communities. The waterways seemed placid, so the new arrivals gave little consideration to the floodplain. Yet Arapaho and Cheyenne sources warned that the South Platte could be dangerous at times, including a flood in 1844 when the river had risen twenty feet.
In May 1864, Cherry Creek flooded, taking out structures in the heart of the new town, including the Larimer Street bridge, the Blake Street bridge, city hall, and the offices of the Rocky Mountain News. Cherry Creek overran its banks six more times in the next fifty years. By the time of the 1912 flood, the city had put up retaining walls and greatly improved the channel. The creek continued to menace the city until the completion of the Cherry Creek Dam in 1950.
Neglecting the South Platte
Denver worked to control Cherry Creek, but little was done about the South Platte itself—even though several of its other tributaries were almost as unpredictable as Cherry Creek. A 1945 study had recommended building a dam and reservoir southwest of the city, where Plum Creek converged on the Platte. In 1950 the proposed Chatfield Dam was authorized by Congress. But property owners in the area did not want the dam, and there was little political will to build it.
In part, the city’s neglect of the South Platte reflected the river’s relatively placid history. Over the first century of Denver’s existence, the South Platte had only one notable flood, in 1885. Most residents paid little attention to the river. Starting in the 1870s, it had become a place of factories and railyards, a dumping ground for whatever the city didn’t want: animal carcasses, used oil and old tires, rejected feathers from a pillow factory, paint and wood shavings, and effluent from dozens of other plants.
By the 1960s, half a dozen landfills had been created along the river. No fewer than 250 drains poured directly into it, spewing stormwater and salt from city streets along with raw sewage. Its banks were choked with weeds, abandoned cars, hobo camps, and trash.
The Flood of 1965
For weeks in late spring 1965, Colorado’s Front Range experienced a number of unusual meteorological conditions, including high winds, hailstorms, and exceptionally heavy rains. On Monday, June 14, southeast Colorado Springs was hammered by golf-ball–sized hail. Funnel clouds were sighted to the north, and one tornado touched down in Loveland, smashing trees and cars.
On Tuesday, the rain and hail swept northeast, a procession of storms from Greeley to Sterling and on to the Nebraska line. Pawnee Creek and Lodge Pole Creek, both tributaries of the South Platte River, jumped their banks and submerged roads in Logan and Sedgwick Counties. Sheep and cattle drowned, and areas of some towns were soon under three feet of water.
The main event came on Wednesday, June 16, starting at about 1:30 pm. It began on the southern edge of Douglas County, with a hard rain and a tornado that ripped through the tiny town of Palmer Lake, peeling the roofs off thirty houses.
Fourteen inches of rain fell on Dawson Butte, north of Palmer Lake, in four hours. “Creeks overflowed, roads became rivers, and fields became lakes—all in a matter of minutes,” wrote flood watcher H. F. Mattai in a report to the US Geological Survey.
The runoff swelled East Plum Creek, wiping out roads and bridges in its path through Castle Rock. The east and west branches of Plum Creek joined forces just outside Sedalia. The combined surge swamped the town’s main street, including seven houses, a church, and the grange hall. The creek, typically no more than a few feet wide, now stretched nearly a mile wide as it headed north. Later calculations indicated that the flow of Plum Creek increased one thousand–fold in less than three hours, from 150 cubic feet per second to 154,000 cubic feet per second (a discharge of one cubic foot per second amounts to about 450 gallons a minute).
North of Louviers, the raging creek poured into the roiling South Platte. State patrol officers reported a wall of water estimated to be twenty feet high headed for Littleton, with a second crest not far behind. A photographer in a helicopter described the bloated river as “a knife of mud, slicing across the green countryside.”
By 5 pm. the Denver Police Department had cleared its radio traffic for emergency calls only. For all its tremendous force, the wall of water was only one concern. Even more worrisome, perhaps, was all the hazardous material in its debris flow: fuel storage tanks, heavy equipment, mobile homes, even brick houses and their foundations, as well as old cars, junked appliances, and the contents of landfills.
The water cut a wide swath through the Centennial racetrack, where most of the thoroughbreds had been evacuated. Meanwhile, debris in the current smashed against Denver bridges like a battering ram. Standing on top of Ruby Hill with his wife and a clutch of other sightseers, The Denver Post staffer John Buchanan watched trailers and houses smash against the Florida Avenue bridge. In addition to the roar of the water, there was a constant grinding sound as one object after another joined the scrum. Buchanan saw explosions and flames rising to the south and “something that looked like skyrockets” above the Gates Rubber plant, even as much of the city was going dark from downed lines and swamped power stations.
One by one, the bridges fell, all the way to the Colfax viaduct—which miraculously held. The flood knocked out thirteen of the twenty-four spans across the river. At Sixth Avenue and Platte River Drive, two large butane tanks ruptured, and the explosion could be heard for miles.
The flood muscled into downtown Denver around 8 pm. Unlike the bridges to the south, most of the viaducts survived the pounding. But the flood had its way with the railyards, the Tivoli Brewery, the warehouses, and the modest houses of the Bottoms west of downtown. Power outages spread; some television and radio stations went silent, while the Rocky Mountain News was forced to use the printing presses at The Denver Post to get out the morning’s sodden disaster coverage.
The downed bridges from Douglas County to Colfax left thousands of people stranded. In all, 1,720 buildings in the city were destroyed or damaged by the flood. Livestock losses were heavy. People also reported seeing human bodies in the flood, but with phones dead and power sporadic, deaths were difficult to confirm. Casualty reports trickled in over the next few days, as the storm front and flooding shifted to the Arkansas Valley, prompting evacuations from Pueblo to Dodge City, Kansas.
If not for Cherry Creek Dam, the deaths in the Denver metro area might have numbered in the hundreds. The reservoir rose sixteen feet the night of the flood, but the dam held.
Four days after the flood hit Denver, President Lyndon Johnson declared a disaster area across twenty-seven Colorado counties. Once the emergency passed, city leaders began to set in motion a plan to prevent similar catastrophes in the future. The flood “forced us to look at the Platte River Valley, and challenged us to do something about it,” Mayor Tom Currigan observed.
The first priority was the need to implement the long-delayed proposal for a dam on the southwest edge of the city. The US Army Corps of Engineers began work on Chatfield Dam in 1967 and completed it in 1975. During its construction the South Platte flooded twice, in 1969 and 1973. Neither event approached the sheer fury of the 1965 disaster, but the other floods did underscore the need to take the river seriously.
An equally significant development was the state legislature’s creation of the Urban Drainage and Flood Control District in 1969. An independent agency spanning six counties, the district has become a national model of multijurisdictional coordination of floodplain management.
The 1965 flood also sparked major changes to downtown Denver. In the late 1960s, the Denver Urban Renewal Authority mounted a campaign to convince voters that the Auraria neighborhood was hopelessly blighted, three-fourths of its housing stock “dilapidated or damaged beyond repair,” in part because of the flood. Actually, less than half of the area had been affected by the flood, but many civic leaders were inclined to eradicate as much of the Bottoms as possible and start over. A bond issue to create the Auraria campus narrowly passed, leading to contentious condemnation proceedings and the dispersal of “displaced Aurarians” who still mourn the loss of their neighborhood.
Despite numerous studies and proposals, the city’s riverfront remained a grim, inaccessible place for several years after the flood. But in 1974 Denver mayor Bill McNichols asked former state legislator Joe Shoemaker to help raise funds for river improvements. Shoemaker worked closely with the Urban Drainage and Flood Control District on projects designed to improve water quality and flood control while making the river a safer, more attractive place. He started by assembling a bipartisan group of community activists and businesspeople to promote construction of the original Confluence Park and another modest riverfront park in Globeville. The committee evolved into the Greenway Foundation, a nonprofit that would work with foundations, municipalities, state lottery funds, and any other sources available to improve the waterways.
Starting with McNichols, Denver mayors began to see the river as an asset worth cultivating. Federico Peña introduced a Central Platte Valley master plan that consolidated rail lines and removed several viaducts, making the river more accessible and changing the warehouse district into “LoDo,” an area of lofts, restaurants, sports bars, and entertainment venues. Wellington Webb declared 1996 “the Year of the River” and advanced the central greenway by creating Commons and City of Cuernavaca parks. Family attractions, such as the Children’s Museum and Elitch Gardens, suddenly saw the value in locating close to the river —and close to the Pepsi Center and Coors Field.
Along with the creation of Chatfield Dam and the city’s various urban renewal efforts, the Greenway Foundation has become one of the most significant outcomes of the 1965 flood. In addition to overseeing a total of $130 million in clean-up and improvements along the Platte and its tributaries, the group has helped create more than 100 miles of hiking and biking trails connecting more than twenty parks (including ten built on former landfill sites) along the waterways.