Flood
When water crossed the spillway on May 9, 1905, the people of Denver did not rejoice. The South Platte River already was roaring through Denver, tearing out bridges as far north as Colfax Avenue. Once Cheesman filled, it could no longer abate the flood. State officials warned in a press release of potential new emergencies.
When the water topped the spillway, messengers rode into Denver to warn of increased flow. Fortunately, no fresh disasters were attributed to the spillway in the ensuing weeks of 1905. Unlike Chatfield Dam, Cheesman was not built to abate the Platte's floodwaters. Its release outlets would temper the river's discharge, but only incidentally, as a side effect of accumulating water for Denver's use. The lowest outlet tunnel can release water when the dam is filled to only 15 of its 212 feet. Cheesman's mission has always been reserving water for year-round use, not controlling the river. Unlike a flood-control dam, Cheesman is kept full when possible.
Drought
The obvious use of a reservoir is to reserve water against drought. Cheesman Reservoir made its first contribution to Denver's welfare even before it was completed. In July of 1902, when other resources ran low, water was released from the incomplete dam to ease the shortage. Once it was built, Cheesman served the water needs of Denver effectively (with Antero for backup) until the 1930s, when Eleven Mile Canyon Reservoir was added to the system during one of the worst droughts to strike the region.
Water shortages are a permanent condition in what 19th-century explorers called, with more accuracy than once thought, "The Great American Desert."
Droughts were frequent, and streamflow for the South Platte varied tremendously from year to year. For example, between 1888 and 1925, the low was 150,000 acre-feet of runoff in 1889 and more than 650,000 acre-feet in 1914, with an average of 300,000 acre-feet per year. In the summer of 1934, drought struck hard. By September, Cheesman was less than one-third full. At its lowest point, the reservoir held only 4,000 acre-feet of water, a tiny fraction of its 79,000 acre-feet capacity.
Fire
Fire has only recently been recognized as a part of forest ecology. In the early days of Cheesman Reservoir, as in the early days of the Forest Service, stewardship meant fire prevention.
Historical data shows that significant natural fires had been occurring at roughly 50-year intervals in the Cheesman area before the reservoir was built. During the reservoir's first century, there were no catastrophic fires (with one terrible exception), primarily because of aggressive fire suppression. Diligent caretakers stopped about 10 fires each year.
When the dam was built, the surrounding hills were a sparse, open landscape of stunted trees and scattered shrubs. By 2000, nature and fire suppression had created a thick, combustible forest around the reservoir.
Immediately after the 1996 Buffalo Creek fire, rains choked Strontia Springs Reservoir, downstream of Cheesman, with mud and debris, silting it to 7 percent of capacity. That fire had been fueled by dense forest; the result of benign neglect conservation. It burned hotter, deeper, and wider as a result.
In 2002, another fire struck, this time the largest in state history. The Hayman Fire burned 7,500 acres of Denver Water property near Cheesman Reservoir, leaving a forest of charred trees in its path. The fires and subsequent rains have created sedimentation and erosion problems that Denver Water is still dealing with today.