Watching water flow over Cheesman Dam’s unique stone spillway is nothing short of spectacular.
The dam and reservoir sit in a remote canyon that straddles the border of Douglas and Jefferson counties about two hours southwest of Denver near Deckers.
When the water level in Cheesman Reservoir behind the dam is high enough, water cascades like a waterfall down the spillway, a 220-foot-high wall of boulders, into the South Platte River below.
The reservoir collects mountain snow that melts and pours into the South Platte River. On June 28, Cheesman filled to capacity and started spilling thanks to abundant snowfall last winter.
Spillways provide an important safety feature for dams, offering a safe path for the water to flow downstream and ensuring large amounts of water do not go over the top of the dam.
Cheesman is unique among Denver Water’s 12 major dams in that it has three ways to move water through the dam.
Five valves at the bottom of the dam serve as the primary way the dam operators can release water. In the middle of the dam is another valve, which functions as a backup to the main valves below. And when water levels in the reservoir are high enough, the operators can choose to send water down the spillway. (Watch this video to see how the three release options lead to happy trout in the South Platte River.)
Cheesman opened in 1905 and can store 79,000 acre-feet of water, nearly 27 billion gallons. That’s enough water to supply 316,256 residential households for an entire year.
The dam is expected to continue spilling water into mid-July. Hikers can catch a peek of the stone spillway in use from a recreational trail at the bottom of Cheesman Canyon.
Bailee Campbell, Denver Water’s video intern, contributed to this story and video.