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Castlewood Canyon Dam
When: Thursday, September 26 • 8:00 AM - 3:30 PM MT
Registration Fee: This field trip has reached capacity.
Castlewood Canyon Dam was constructed in 1890 across Cherry Creek, 40 miles southeast of Denver, Colorado. The masonry and rock-fill structure, built from local materials, was around 600 feet long with a height of 70 feet measured from the reservoir floor, 8 feet wide at the crest, and 50 feet wide at the base. The dam was regulated by an outlet structure with eight 12-inch inlet pipes and one 26-inch outlet pipe. The dam had a 100-foot long by 4-foot-deep notched uncontrolled spillway at the center of the crest and a 40-foot-wide masonry-lined bypass spillway near the left abutment. The 5,300 acre-feet of storage was used for irrigating fertile Douglas County farmland, dotted with dairy farms, potato fields and orchards.
In late June and early August of 1933, locals experienced a continued wet period. Some estimated the wet spell to be three days, others as long as a week. On the afternoon of August 2nd, between 4 to 9 inches (estimates vary) of rain fell in approximately three hours from a localized storm event.
At around 11:15 p.m. on the evening of August 2nd, 1933, the reservoir level behind Castlewood was about 6 feet below the spillway crest. By midnight, the water level had risen to the crest of the dam, and only 15 minutes later, water was overtopping the dam crest by approximately one foot. It is estimated that approximately one hour later, around 1:20 a.m. on August 3rd, 1933, Castlewood Canyon dam was breached, sending a wave of water down the canyon towards Denver. Peak discharge immediately downstream was later estimated at 126,000 cubic feet per second (cfs).
Ultimately, the failure of Castlewood Canyon Dam caused two fatalities and $1M ($20M in 2018) worth of damage to crops, property, and animals, yet could have been substantially worse.
The trip will include an organized tour of the dam along with other park features. The tour will be conducted by Castlewood Canyon Park staff; however, staff may have limited knowledge of the actual failure. More information on the failure can be found on
DamFailures.org.
Participants will walk approximately 2 miles on this trip. The walk is mostly flat, but there is one 200-foot elevation gain. Participants are urged to bring sunscreen and water. Shorts are acceptable, but participants should dress in layers to be prepared for the changing weather. Make sure to wear comfortable shoes with good tread.
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