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Franktown, Colorado

Castlewood Canyon Dam Ruins

The remains of the dam that unleashed a 15-foot wall of water on Denver. 

Crumbling away in a verdant state park, the ruins of the old Castlewood Canyon Dam hardly looks like the remains of a sturdy industrial water wall that released a torrential flood on the surrounding area when it finally broke. 

Built in 1890 and leaking for years after that, the Castlewood Canyon dam collapsed on August 3, 1933.  A storm raged on that day, filling the dam’s reservoir to bursting.  When the crumbling stone barrier finally failed, over a billion gallons of water were released, traveling over 40 miles of surrounding wilderness before eventually flooding Denver. Huge logs were floated through train stations, bridges were washed away, and by the end of the torrent, the whole city was sitting in four feet of water. Luckily (and tragically) only one person was killed, but the property damage of the catastrophe was immeasurable. 

While it was likely just age and a lack of maintenance that caused the dam to give way, some residents who still remember the disaster claim that it could have been the local muskrat population effecting the integrity of the dam. No matter the cause, the ruins of the dam remain in Castlewood Canyon State Park. Either side of the structure still remains and the track through which the water broke through is now a dry, grassy thoroughfare.  

Know Before You Go

Use the West Entrance. 0.3 mile moderate walk. Bring good hiking shoes.