Boulder’s powerlines pose wildfire risk. Why are so many still above ground?

This story is part of a new series, Rewiring Boulder, examining local solutions for a power grid under pressure from wildfire and climate change.

As wildfire risk grows in Boulder, the city’s above-ground powerlines are becoming harder to ignore.

While much of Boulder’s power system now runs underground — about 71% of lines, or roughly 350 miles, within city limits — about 140 miles remain overhead, often in areas most exposed to wind and debris. Those lines can snap or spark when debris makes contact, turning routine failures into ignition risks.

To reduce that risk and its own liability, Xcel Energy has begun cutting electricity during periods of extreme fire danger, a practice known as public safety power shutoffs. But those outages bring risks of their own and are becoming more frequent and disruptive.

Even when power is not intentionally cut, the system has become more sensitive. Xcel now automatically disconnects lines under certain conditions, leaving neighborhoods without electricity until crews can inspect and restore service.

Those disruptions have sharpened a longstanding question: Why are Boulder’s powerlines still above ground, especially when burying them can reduce ignition risk by as much as 95%, according to Xcel’s estimates. 

The answer stretches back more than half a century to a funding system that has never kept pace with the cost or scale of the work. Xcel owns and operates Boulder’s electric grid and performs the construction. Under the city’s franchise agreement, the utility is required to set aside 1% of its local revenue for undergrounding projects selected by the city and carried out by Xcel. 

But that funding has consistently fallen short, and efforts to raise more have not succeeded. In other communities, including Longmont and Fort Collins, broader undergrounding has often been driven by municipal ownership of the utility or regulatory requirements that do not exist in Boulder.

A plan built for aesthetics, not wildfire risk

The first push to underground powerlines in Boulder dates to the 1970s, according to newspaper archives and city records, but for very different reasons than today.

In 1970, Boulder voters approved a franchise agreement with Public Service Company of Colorado, now a subsidiary of Xcel, requiring the utility to reinvest 1% of its local revenue into burying overhead lines, at the city’s discretion. The city had already begun requiring developers to underground lines in new subdivisions, with the costs passed on to builders.

The measure passed by a wide margin, 8,452 to 1,149, more than 8 to 1. It “was one of the biggest majorities on record in local elections,” a Daily Camera editorial said in 1970.

At the time, the effort was largely about appearance. City leaders wanted to remove overhead wires that cluttered views and disrupted the landscape, particularly along major corridors. The agreement itself framed undergrounding as an improvement to the city’s “aesthetic environment.”

Even then, officials understood the scale of the task. A city council memo from March 1970 warned that “the magnitude of undergrounding needs are probably much higher than the city had anticipated,” according to city records.

City leaders also backed a separate excise tax on electricity use to accelerate the work. Voters rejected it. The 1970 Daily Camera editorial attributed the failure to economic conditions and already high taxes, noting at the time: “Which merely means the [undergrounding] program will go much slower than if the tax had been approved.”

That decision helped set the pace for the program in the decades that followed.

A funding gap that never closed

Through the 1970s and 1980s, undergrounding expanded gradually as projects were completed with the limited funds available.

By the late 1980s, however, the conversation began to shift. A study from CU Boulder raised concerns about potential health effects from low-level electromagnetic fields, including links to cancer and other cellular impacts. The research helped sustain public interest in undergrounding into the 1990s, even as those claims were not substantiated by subsequent science. 

In 1990, a proposed line in Gunbarrel drew strong public opposition over electromagnetic fields and was ultimately built underground. That same year, more than 2,100 North Boulder residents signed a petition to underground a transmission line for the same reason. Concerns about potential health effects from electromagnetic fields persisted throughout the decade, according to newspaper archives. An article from 1999 included a resident who believed that undergrounding lines would neutralize their energy fields.  

Even as those concerns kept public interest high, by the 1990s, the limits of the city’s approach were becoming clear.

About 43% of Boulder’s powerlines had been buried, supported by more than $5 million in investment since 1970. But the cost of remaining projects far exceeded the money available. City documents from 1990 estimated nearly $1.9 million in planned work, compared with about $930,000 in the fund. Annual revenue at the time was roughly $550,000.

City staff urged officials to think bigger. In April 1990, they recommended developing a long-range capital plan to underground the city’s entire system of transmission and distribution lines. Other options were considered, including special improvement districts that would allow neighborhoods to finance projects themselves, often through bonds repaid over time.

Public support appeared to be there. A 1995 city survey found most residents would be willing to pay to bury powerlines.

But the economics remained challenging, particularly for large transmission corridors. “Undergrounding transmission lines is a different animal,” said Lex Telischak, a city electrical engineer who manages the city’s 1% fund, noting the higher voltage and cost.

Efforts back then centered on the Grape Avenue line, which was estimated to cost about $4 million, far beyond what the city could afford.

Of roughly five miles of line, only about a quarter-mile was ultimately buried, near the Goose Creek floodway. 

The funding gap persisted into the next decade.

A decade-long pause, then a restart

In 2010, Boulder exited its franchise agreement with Xcel while pursuing municipalization of its electric utility, an effort to take control of its power system and transition to cleaner energy sources. Under a municipal utility, advocates and city leaders expected greater control over undergrounding, even if it was not seen as a primary motivator. Without the franchise agreement, the 1% fund that had supported undergrounding for decades was suspended.

The loss of funding became a central argument for critics of municipalization, who viewed it as a missed opportunity to continue burying lines.

When the city reentered the franchise agreement in 2020, Xcel paid out the accumulated backlog, about $11 million. Combined with new annual contributions, the city had roughly $16 million to spend on undergrounding projects between 2021 and 2025.

Those funds have since been used for projects along North Broadway, East Arapahoe, 19th Street and Chautauqua, according to Carolyn Elam, the city’s sustainability senior manager. Only one of those projects, in Chautauqua, was explicitly tied to wildfire risk.

Xcel also has its own undergrounding projects slated to begin construction this spring along 75th Street and North Foothills Highway, aimed at reducing wildfire risk. Other hardening projects are planned for the mountains, where overhead lines run through dense vegetation and steep terrain, increasing the likelihood that wind or falling trees could bring them down. These lines supply some of the city’s electricity and run through areas where shutoffs are most likely, making undergrounding there especially critical for reliability and safety in the city as well. Efforts are funded under Xcel’s wildfire mitigation plan.

At current pace, decades remain

Since Telischak began managing the 1% fund, undergrounding has typically aligned with city transportation projects, and costs range from $2 million to $7 million per project. The fund is currently accruing around $1.3 million per year, requiring the city to wait several years before new work can begin. The fund was most recently spent on the Chautauqua undergrounding effort. 

It can take around six months to underground one mile of line, depending on terrain, permitting and coordination with other infrastructure. At that pace, undergrounding the roughly 140 miles of remaining overhead lines would take decades, about 70 years if completed one mile at a time, though actual timelines depend on funding and how many projects can move forward simultaneously.

As for Grape Avenue, Telischak said that Xcel is considering rebuilding those lines, which are now about 100 years old. The corridor, first identified decades ago as a candidate for undergrounding, remains largely unchanged. 

The next story in this series will examine the status of Xcel’s undergrounding projects underway in and around Boulder, and why they matter for the city’s reliability and wildfire risk.