Glenn's Dam Historic District
The ruins of Glenn’s Dam (locally known as Hefner’s) represent a rare nineteenth-century example of a Montana earthen dam used for industrial processing. Additionally, the ruins are vivid reminders of Anaconda’s early rise to prominence as a major ore-processing center. Marcus Daly bought Butte’s copper-rich Anaconda Mine in 1880. Realizing that profits hinged on smelting the copper nearby, Daly created the Anaconda Company with San Francisco investors and purchased land along Warm Springs Creek for a smelter site. In 1883, as construction of the smelter progressed, workers upstream built a headrace (to divert water from the creek), a reservoir, a dike, and two earthen dams. A metal pipeline then diverted water from the reservoir two miles downstream (by gravity) to the new Upper Works smelter. Water was the main source of power used for copper-ore smelting and auxiliary functions. Completed in 1884 and named after its first watchman, William Glenn, the dam featured a massive 540-foot-wide earthen embankment. Two years later, the Anaconda Company purchased new equipment and doubled the plant’s ore-processing capacity—significantly increasing its water requirements. To meet that need, the Company built a much larger “Highline” flume to replace the pipeline. The Highline also served the Lower Works, completed in the late 1880s. A third “Jones” flume, added in the mid-1890s, again increased capacity. The Company abandoned Glenn’s Dam in 1902 after completion of a much larger water system to serve its new Washoe Smelter. After 1959, workers breached the dam and partially drained the reservoir.
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