Built in 1890 along Cherry Creek south of Franktown, Castlewood Dam was meant to help irrigate Douglas County farms. In 1933 the dam gave way, unleashing a fifteen-foot surge of water on Denver and ultimately spurring development of the Cherry Creek Dam to prevent future flooding. Today the ruins of the Castlewood Dam are a historic site protected as part of Castlewood Canyon State Park.

Construction

The Castlewood Dam was planned as part of the agricultural development of Douglas County, which remained an isolated, sparsely populated region until the arrival of the Denver & Rio Grande Railroad in 1871. Soon the country south of Franktown was settled by groups of Germans, a few French, and some Scandinavians. Potato farming and dairy ranching became principal industries in the county. With the growing importance of farming in the region came the need for irrigation. In the late 1880s, a plan was made to build a dam on Cherry Creek in Douglas County.

The Colorado General Assembly first broached the idea of building a dam at the site in 1889.  But when the state failed to follow through, a private entity, the Denver Water Storage Company, was organized to build a dam some forty miles south of Denver and create a 180-acre reservoir for farming and manufacturing purposes. The Denver Water Storage Company purchased 16,000 acres downstream from the dam site, which it hoped to sell to future settlers in forty-acre tracts.

On March 6, 1890, the Rocky Mountain News reported that eighty-five men were working on the dam at Castlewood, with an additional 250 men and 180 teams employed on the ditch running down Cherry Creek Canyon. The dam was designed by engineer A. M. Wells and completed that summer.

Problems

No sooner had Castlewood Dam been built than it became a focus of controversy. Many Denver residents still remembered the Cherry Creek flood of 1864, one of the worst in the city’s history, and worried that the Castlewood Dam could give way. In May 1891, a committee of Denver citizens formed to protest what they believed to be unsafe conditions at the dam. In a petition to the Denver mayor, the citizens’ group charged that the excavation for the foundation of the dam was insufficient and that it was already leaking. In response, W. F. Alexander of the Denver Water Storage Company sent a note to the mayor that characterized the committee’s report as a “low-lived attack from prejudiced persons” who “deliberately falsified” their statements. According to Alexander, “the idea of a flood in Denver as a result of the breaking of the dam is ridiculous.”

Denver’s concerned citizens evidently knew more about the dam than Alexander. In 1897 a 100-foot section washed out and did some downstream damage. Repairs were made, but Denverites remained nervous about the possibility of the entire dam giving way. Heavy rains in the spring of 1900 led to speculation that Castlewood Dam would break. In an attempt to quell these rumors, Wells wrote a letter to the Denver Times on May 2, 1900. “[The dam] has for ten years withstood every test and attempt to produce disaster,” he noted, “and in the past few days has undergone an ordeal which few dams on earth ever endured and survived. . . . The Castlewood Dam will never, in the life of any person now living, or in generations to come, break to an extent that will do any great damage either to itself or others from the volume of water impounded, and never in all time to the city of Denver.”

However, it appears that those associated with the construction of Castlewood Dam were too invested in the project to be objective. Under the pressure of the rising reservoir behind the dam, large holes developed at the bottom of the structure. It leaked so badly that in March 1901 local farmers complained that there was no water in the reservoir for irrigation. On April 13, 1901, the state engineer told the Denver Times that “there is absolutely no danger from the dam this year, as the dam will not hold water.” That same year the Denver Water Storage Company went bankrupt, and Castlewood Dam became the property of the Knickerbocker Investment Company of New York, which had loaned $185,000 for the project. In May Knickerbocker sold the dam to Seth H. Butler of Middletown, Connecticut, for $8,000.

Repairs

In February 1902 the Denver Sugar, Land and Irrigation Company acquired Castlewood Dam. This company, backed by local investors, planned to repair the dam, build a sugar factory, sell off irrigated farmland below, and encourage Cherry Creek farmers to grow sugar beets. The company soon completed its repairs and acquired 18,000 acres of land downstream, which became known as “Clark’s Colony,” after Rufus “Potato” Clark, the venture’s founder.

The company’s land sales got off to an auspicious beginning, with some 2,000 acres sold by April 1903. However, the project hinged on the construction of the sugar factory, which was never built, in part because local farmers did not want to grow beets and feared that a sugar factory would pollute their water. Eventually a new company, the Denver Suburban Homes and Water Company, took over the Castlewood Dam project. This company acquired land downstream from the dam, planted about 900 cherry trees, and attempted to sell off small tracts of irrigated land as orchards to easterners who wanted to retire to a western suburban setting.

Around 1912 the orchard scheme encountered financial difficulties, with the issue of water rights going to court. While the property was in receivership, the cherry orchards were not properly tended and many of the trees died. The case was finally resolved in 1923, when the project was reorganized with the individual landowners sharing the rights to water from Castlewood Dam and reservoir. In the early 1930s about 150 landowners organized as stockholders in the Cherry Creek Mutual Irrigation Company. The company managed the dam and ensured that downstream users got their supply of water. Water from the reservoir irrigated about 2,500 of the 9,000 acres below the dam; the rest was left for dry farming or pasture. Most of the land tied to this project was planted in alfalfa, with some grain and miscellaneous crops cultivated.

The Dam Breaks

Finally—in 1933—the event that Denver residents had dreaded since 1890 came to pass. A series of summer thundershowers filled the reservoir to capacity. Then, at 1:20 am on August 3, Castlewood Dam gave way, sending a wall of water fifteen feet high down Cherry Creek Canyon. The caretaker at the dam, Hugh Paine, saw what was happening and hurried to Castle Rock to spread the news. Nettie Driscoll, Parker’s telephone operator, warned the Denver police of the flood. Time Magazine offered a gripping account of the disaster:

Cherry Creek was a battering-ram of water, boiling over its embankments. At 7 o’clock it burst into Denver, ripped out six bridges in swift succession. Just ahead of it were police cars and fire engines, sirens a-scream, racing the residents to safety. A stampede of 5,000, many clad in night clothes, fled from the lowlands. In the yard of his house, Tom Casey, 80, fell into a hole, could not pull himself out. The torrent surged over him, stilling his screams. Power lines were destroyed, houses canted. The flood poured into store basements, soaking tons of merchandise. The Market Street produce centre was buried in three feet of water. The City Auditorium, fire and police headquarters, the city jail were flooded. The floor of Union Station was covered six inches deep, a log came bumping into the waiting room.

On Champa Street, the floodwaters extended as far uptown as Thirteenth Street. Portions of the concrete walls along Cherry Creek were torn up, and waves spilled over onto Speer Boulevard. By 8 am the torrent was subsiding. Later that afternoon Denver slowly regrouped and appraised the impact. The Denver Post reported it as the city’s worst flood since 1864. Hundreds of acres of farmland were inundated, and many stock animals drowned. Besides poor Tom Casey, there was a fatality in Franktown. Property damage in Denver was estimated to be over $1 million.

Flood Control

The disaster of 1933 forced the city of Denver to seriously consider a comprehensive flood-control program for the Cherry Creek drainage, which ultimately led to the building of the Cherry Creek Dam. City officials proposed a plan that would include the walling of Cherry Creek from University Boulevard to Colorado Boulevard and the construction of a diversion dam across the creek channel several miles southeast of Denver. The site for the dam on Cherry Creek near Sullivan, later referred to as the Kenwood Dam, was acquired by the city of Denver late in 1934, and construction began the following year on the forty-five-foot earthen structure.

Business owners who had suffered during the 1933 flood organized the Denver Flood Control Association and began to lobby the federal government for the construction of a better flood-control system on Cherry Creek. One of the options under consideration by the Department of Agriculture, Bureau of Reclamation, and Army Corps of Engineers was the reconstruction of Castlewood Dam. In April 1940 a spokesperson for the Army Corps of Engineers recommended that Castlewood Dam be rebuilt and that another dam be constructed on Cherry Creek closer to Denver. He stated that while the Kenwood Dam, already in place, was sufficient for ordinary situations, it could be destroyed by a strong basin-wide flood, which would inundate Denver.

In August 1941, President Franklin D. Roosevelt signed into law a bill giving official authorization for the Cherry Creek project as part of a $275 million national flood-control program, and in April 1946 Congress approved a specific appropriation of almost $3 million for flood-control work on Cherry Creek. Land for the dam on Cherry Creek was then acquired and ground broken at the site in July 1946. The new dam was planned to be 140 feet high and almost 3 miles long. Under supervision by the Army Corps of Engineers, the dam was completed in January 1950 at a total estimated cost of $18 million. Proponents claimed that the Cherry Creek Dam proved its worth on June 16, 1965, when it stopped the largest flood in the area’s history.

Today

As late as the early 1970s, the Army Corps of Engineers still considered rebuilding Castlewood Dam as part of the Cherry Creek flood-control project. By that date, however, local residents were against the idea, believing that the Castlewood Dam was not really necessary with the Cherry Creek Dam already in place. In May 1972 political pressure forced the Corps to drop their plans for a new dam at Castlewood. Instead, concerned citizens recommended that Castlewood Canyon State Park be expanded.

The park had its origins in 1961, when Lawrence P. Brown gave eighty-seven acres of land to the state park system for only ten dollars. In 1964 that land became Castlewood Canyon State Park. The park grew in 1979–80, when the state acquired an additional 800 acres, including the old Castlewood Dam site. Trails built since the 1980s allow visitors to tour the canyon and ruins of the dam. Today the park preserves more than 2,300 acres of the unique Black Forest ecosystem and part of the Cherry Creek floodplain.

*Adapted from Paul D. Friedman, “To Tame Cherry Creek: The Birth and Death of Castlewood Dam,” Colorado Heritage no. 1 (1987).