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South Platte at Denver

May 6-7, 1973

 
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To view the summary as a pdf document (printer friendly) click here
Rainfall Data: click here
Damage Estimate: According to the National Weather Service, damages from the flood were estimated at around $120 million (http://www.crh.noaa.gov/den/floods.html). The following damage estimates were printed in the Denver Post on May 13, 1973. Damages estimates in Weld County, hardest hit by the flood, were $20 million. In Adams County, the estimate was $8 million. In Denver, the estimate had climbed to well over $6 million and in Jefferson County, officials were reporting over $500,000 damage to roads, culverts, and other county property.
Deaths: 2

“The 1973 flood was the last big flood in Denver” (Brian Schat, Denver Public Works, personal communication 8/22/03). Rainfall was widespread along the Front Range with totals ranging from one to five inches. A sustained downpour dropped more than three inches in the Denver metropolitan area on Sunday, May 6. In the foothills, heavy snow fell.

Most of the damage was a result of river flooding. The South Platte was four feet above flood level at its crest when it measured 10.85 feet at the 19th Street Bridge early on the morning of May 7. The flood stage of the South Platte at W. Evans Ave. equaled that during the 1965 disaster. However, this flood was more of “a steady overflowing of water” as opposed to the “one surge” Denver experienced during the flood of 1965.

The South Platte flooding was compounded when normally dry gulches and tributaries from the mountains west of Denver became turbulent flows that emptied into the river. When Bear Creek reached southwest Denver, it had grown to be 150 yards wide in spots. Plum Creek and Indian Creek, other South Platte tributaries, also poured out of their banks, virtually isolating the town of Louviers. In Englewood, the Highline Canal and the normally dry Little Dry Creek both overflowed.

More than 3,500 people were evacuated from their homes as floodwater poured onto land from Douglas County 175 miles north to the Colorado-Nebraska border. In the Denver metropolitan area, Englewood, the Wellshire section of southeast Denver and the area around S. Santa Fe Drive and W. Alameda Drive were the hardest hit areas. Seven low-lying areas in Adams County were evacuated in addition to evacuations in the Wellshire neighborhood, a portion of Englewood, and outlying areas in Adams County, Douglas and Weld Counties.

Before evacuations were ordered in Denver, water began rising in Turkey, Bear, and Clear Creek Canyons because of the heavy snow runoff on May 5. By May 6, several Jefferson County roads in those areas had been washed out and residents had to be evacuated. In addition, several rock and mudslides forced road closures.

Officials claimed that Denver was saved by a major effort to keep the South Platte River channel from backing up with flood debris at bridges. Several cranes and other construction equipment were used to clear the river. This work helped eliminate the ‘wall of water' effect that caused the greatest damage in 1965. Only one bridge, over 15th Street, was lost in Denver. Many streets were closed in and the Valley Highway was once again flooded and closed for several days.

As the flood subsided in the Denver metro area on May 7, South Platte tributaries to the northeast of the city caused great problems. The town of Roggen, on the Lost Creek tributary in Weld County, and the town of Wiggins, on Kiowa Creek in Morgan County were the hardest hit. The biggest contributing factors to the flooding in those areas were highway and railroad bridges that were clogged with debris. Water levels were as high as four feet in parts of the town of Wiggins. There it is believed that a bridge served to divert Bijou Creek directly into town.

Eight to ten bridges were out across the state. The damage to agricultural lands was expected to surpass that of the 1965 flood. The most costly effect of the storm was the delay in planting of crops and delay in growth of grass for pasture in addition to the extensive loss of irrigation channels, ditches and support lines. Two drowning deaths were a result of the floods.  

Rainfall Data:

Date
Location
Peak Rainfall
5/6
Byers
4.1” in 24 hrs.
5/6
Deer Trail
3.71” in 24 hrs.
5/6
Denver WSFO AP
3.27” in 24 hrs.
5/6
Evergreen
2.70” in 24 hrs.
5/6
Greenland 6 NE
3.39” in 24 hrs.
5/6
Greenland 9 SE
2.78” in 24 hrs.
5/6
Hoyt
2.38” in 24 hrs.
5/6
Manitou Springs
2.00” in 24 hrs.
5/6
Morrison 1 SW
3.00” in 24 hrs.
5/6
Palmer Lake
1.60” in 3 hrs, 4.10” in 24 hrs.
5/6-7
Kiowa
6” (estimate) in 24 hrs.
5/6-7
Near Broomfield
5.31” in 31 hrs.

 

Sources

-The Denver Post, May 7-8, 13, 1973

-McKee, T.B., Doesken N.J, Colorado Extreme Storm Precipitation Data Study, Colorado State University, Dept. of Atmospheric Science, Ft. Collins, 1997.

-Storm Data, May 1973


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