Wildfire project reveals hidden history of Boulder’s 100-year-old hydro system

The recently announced Tram Hill Fuel Reduction Project on city-owned property west of Boulder has already produced reader questions about the area’s history. As it turns out, the corridor selected for tree removal — between Flagstaff Road and Boulder Canyon — overlaps a pressure pipeline in Boulder’s more than a century-old hydroelectric project. A “tram line” on what is now known as Tram Hill transported the building materials needed for construction.

This existing pipeline (on Tram Hill), however, is only one of the project’s main components. In 1908, construction began on Barker Dam, near Nederland. From there, a gravity pipeline still transports water to Kossler Reservoir, west of Flagstaff Mountain. The water then drops 1,821 feet down Tram Hill through the pressure pipeline before generating power with two water wheels and two generators inside the plant in Boulder Canyon.

When the Boulder Canyon Hydroelectric Project was completed in 1910, it was considered an engineering marvel. It still is today.

Boulder’s hydro project was part of an ambitious plan by the Eastern Colorado Power Company to create multiple hydro plants and power lines in the Rocky Mountains. Only the Boulder and Shoshone (on the Colorado River near Glenwood Springs) projects, however, materialized. 

To obtain the water needed to power the plant, the company created Barker Reservoir, on land east of Nederland previously owned by businesswoman and civic leader Hannah Barker. Its 175-foot dam, straddling Middle Boulder Creek, was built by hundreds of laborers, mostly immigrants. In 1910, a federal census-taker documented their countries of origin as Germany, England, Sweden, Denmark, Austria, Greece, France, Turkey, and Bulgaria.

To create the 11.7-mile gravity pipeline to Kossler Reservoir, two-foot sections of pipe, 36 inches in diameter, were cast in a meadow on Magnolia Hill. Laborers then crossed heavily forested areas, rugged hillsides, and sheer rock faces to build a trench. They laid the pipe in sections and cemented them together. 

Kossler Lake only needed two earth embankments to make it usable as a reservoir. From there, additional laborers built the pipeline (on Tram Hill) down to the hydro plant, then under construction in Boulder Canyon. The pipe (called a penstock) decreases in diameter as it goes downhill, creating the needed water pressure to generate electricity.

At least since the 1940s, “Tram Hill” has shown up as a geographical feature on topographic maps. Newspaper reports and photos from the cable tramway’s construction in 1906 confirm that it was “built of heavy rail and securely anchored on the slopes.” Small rail “cars” (similar, perhaps, to ore cars used in mining operations) carried pipes and cement from the site of the power plant up the steep mountainside. 

Jack Kossler, one of the laborers and the son of the ranchers who originally owned Kossler Lake, was interviewed, years later, by a newspaper reporter. “The cars ran over steel rail laid on ties about four feet apart,” he stated. “Three steam-operated hoists pulled the cars up. The first [hoist] was at the big flat about one mile above the plant. The second a half mile above that, and the third at the [Kossler] lake.” Jack also recalled that work crews rode in the tram. One time, on the way down, they were overloaded and had a “wild ride.” They never rode the tram again.

Company ownership of the hydro project changed throughout the years, with the Public Service Company of Colorado becoming a partner in 1924. The city purchased the entire project in 2001. Since that time, the plant has operated primarily as a municipal water supply, while also generating power when there is excess capacity in the system. (For additional information, see here.)

Boulder’s hydro plant is visible from the east side of the only tunnel in Boulder Canyon, on Colorado 119.

The hydro project’s completion was celebrated on Aug. 4, 1910. Accompanied by nearly 100 Boulder and Denver dignitaries, Boulder Mayor A.A. Greenman pulled a lever that set in motion one of two 10,500-horsepower wheels. A Daily Camera headline read, “Big wheels revolve at mayor’s touch.”

The assembled crowd was told that the newly generated power was being sent to Denver via a steel tower transmission line and connected there with the line from the Shoshone plant. Meanwhile, a reporter noted, “Flashes of lightning from the heavens added to the crackling sensation of a great electric plant and affected the nerves of some of the spectators.”

Unbeknown to these same spectators, the Boulder plant was not yet ready for the water to hit the turbines, or for the turbines to spin the generator. Not wanting to cancel the celebration, the plant operators arranged for power from the Shoshone plant to be transmitted to the Boulder plant when the mayor pulled the lever. According to company records, none of the visiting dignitaries suspected the sleight of hand.