Attachment A - Boulder Electric Grid State of the System

Study Session, April 23, 2026 · item Study Session Items2: Power Reliability and Resilience Staff Time: 30 Min Council Time: 60 Min · 34 pages

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Draft – April 2026

Boulder’s Electric Grid: Reliability and Resilience Policy Roadmap Initial Outline April 2026

Draft – April 2026

Preface This draft is intended to present a proposed framework for a Grid Reliability and Resilience Policy Roadmap, which would be the final deliverable for Boulder City Council’s 2026 Priority Project. The detailed roadmap would be accompanied by a shorter informational graphic. This draft provides an initial review of the electric grid serving the Boulder community, including its history and architecture, the wildfire risks it now poses, and emerging reliability and resilience concerns. The report also begins to map expected investments that will be made by Xcel Energy (Xcel) over the next decade to reduce wildfire risk, improve reliability and ready the grid to support future demands. The report was prepared by City of Boulder staff with input from Xcel.

Draft – April 2026

Table of Contents Executive Summary........................................................................................................5 Evolution of Boulder’s Electric Power Grid .................................................................7 History ......................................................................................................................................7 Components and Layout ........................................................................................................9 Overhead Verses Underground Construction ....................................................................10

Utility-Ignited Wildfire Risk ..........................................................................................11 Deadly Fires ...........................................................................................................................11 Camp Fire, California .........................................................................................................................12 Lahaina Fire, Hawaii ..........................................................................................................................12 Smokehouse Creek, Texas Panhandle..............................................................................................13 Eaton Fire, California .........................................................................................................................13

Risk Factors ...........................................................................................................................14 Climate Change .................................................................................................................................14 Wildfire Consequence ........................................................................................................................15 Infrastructure Age...............................................................................................................................15

Boulder’s Utility-Ignited Wildfire Risk and Mitigation Impact ..................................16 Xcel’s 2025-2027 Wildfire Mitigation Plan ...........................................................................18 North Boulder Undergrounding ..........................................................................................................19 Northwest Boulder Sectionalization and Hardening...........................................................................20 West Central Sectionalizing, Undergrounding and Rebuild ...............................................................20 South Boulder Undergrounding and Sectionalization ........................................................................21 East Boulder Undergrounding, Sectionalization and Rebuild ............................................................22

Other Reliability Concerns...........................................................................................24 Underground Cable Failures ..............................................................................................................24 Wildlife Contact ..................................................................................................................................24 Vegetation ..........................................................................................................................................24

Disparate Impacts..................................................................................................................25

Xcel Planned Investments Beyond Wildfire Mitigation .............................................26 Asset Health and Reliability Investments ...........................................................................27 Substation Rebuild and Expansion .....................................................................................27 Capacity Expansion ..............................................................................................................27

Community Engagement .............................................................................................27 Policy Roadmap............................................................................................................27

Draft – April 2026 Conclusions ..................................................................................................................29

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Executive Summary Reliable electricity supply is vital to the community’s safety, health, well-being and economic vitality. Yet the infrastructure that supplies this life blood has inherent vulnerabilities that present risks to both reliability and safety. The labyrinth of high- and medium-voltage power lines that make up Boulder’s electric grid traverse both overhead and underground throughout the community and the wildlands that surround Boulder. While both overhead and underground are vulnerable to outages, the risks and consequences of outage differ. Overhead lines, while less costly to construct and easier to repair than underground lines, are susceptible to damage from extreme weather. Underground lines can be 4-10 times more expensive to construct and, while far less vulnerable to weather, they are more difficult to diagnose and repair, resulting in longer duration outages when failures do occur. With increasingly dry winters, more frequent droughts and increased severity of storms because of climate change, the vulnerability of overhead power lines to extreme winds poses a material threat to communities like Boulder that abut wildland areas. Energized power lines failing and igniting dry vegetation in high winds can lead to devastating wildfire. In response to the growing threat of utility-ignited wildfire, utilities throughout the western United States have begun proactively de-energizing power lines during highrisk conditions, known as Public Safety Power Shutoff (PSPS). Safety protections devices are also programmed to more sensitive settings, known as Enhanced Power Safety Settings (EPSS), so that power lines will immediately de-energize upon fault. Boulder’s serving utility, Xcel Energy (Xcel), conducted its first PSPS event in Colorado in April 2024, which had widespread impact on Boulder and surrounding areas of Boulder County. Also beginning in 2024, Xcel began to use EPSS and, as a result, throughout 2024 and 2025, Boulder experienced multiple wide-impact EPSS outages, and this trend has continued into 2026. In December 2025, Xcel implemented its second and third PSPS events on the 17th and 19th, respectively. While not impacting Boulder, another PSPS was conducted by Xcel in January 2026, focused on northern Colorado, and in February 2026, Black Hills Energy conducted its first PSPS in areas near Pueblo. On March 14, 2026, the Boulder community was again impacted by a PSPS. Xcel has also conducted multiple PSPS events in its Texas and New Mexico service territory. In addition to the wildfire mitigation-related outages, Boulder has experienced an increase in outages due to underground equipment and cable failures, substation equipment failures, and weather-related damage to overhead lines from high winds, downed-vegetation and other debris. While outages events are not new to areas of the community, the past two years have seen a material shift in magnitude, duration and

Draft – April 2026 consequence of outages. At the peak, 60% of Boulder was left without power on December 17, 2025, with outages lasting from several hours to several days. Based on Xcel’s 2025 quality of service data, Boulder ranked worst in the state for the number of customers experiencing 6 or more outages, while Nederland ranked the worst for customers experiencing outages of more than 18 hours.1 The community’s recent experiences with outages are illustrative of the now-realized nexus of increased wildfire threat due to climate change and growth within the wildlands, and the increased risk posed by aging grid infrastructure. These experiences have surfaced outage vulnerabilities of critical city infrastructure, resulted in substantial financial losses for residents and businesses, and threatened the health and well-being of medically vulnerable community members. While Xcel is working to harden and improve its infrastructure, it will be several years before PSPS and EPSS become less necessary in Boulder. Additionally, work Xcel has planned will not fully resolve all of Boulder’s reliability risks. City Council established the Power Reliability and Resilience project as a 2026 council priority with the goal to better understand Xcel’s current and planned actions to improve grid reliability and resilience and to identify what roles, authorities, and strategies the City of Boulder could pursue to reduce outage risk and community impacts. This effort is intended to develop a clear, actionable understanding of grid resilience risks, utility investments, and city-led or city-enabled options to reduce power outage frequency, duration, and community harm, and to identify community supports necessary when extended outage does occur. [Final version will include summary of the project outcomes and the prioritized policy recommendations for future councils to consider.]

1 Noteworthy due to the location of city critical infrastructure in this area and to wildfire risk.

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Evolution of Boulder’s Electric Power Grid History Electric infrastructure in Colorado began to be constructed in the 1880’s, but it was with the completion of Boulder Canyon Hydroelectric Plant in 1909 that Boulder’s electric grid emerged. To connect the hydroelectric plant to the growing community at the base of the foothills, towering structures were constructed along the rugged terrain, with one line heading north and then east across Mount Sanitas and the other heading south towards Eldorado Canyon. While the structures to the south were replaced in recent years, the original 1910s era structures still sit in the rugged mountain areas north of the dam, along with the later-added connection known as Sunshine tap that connects to the Sunshine substation on the west side of Boulder. As Boulder rapidly grew in the 1920s, Valmont Power Plant was constructed bringing power into the community from the east. It is this early 1900s architecture of the loop to the west and a second to the east that became foundation of the grid that serves Boulder today.

Figure 1 - Boulder Hydroelectric Power Plant

Draft – April 2026

Figure 2 - Photo of Boulder Hydro Substation

Figure 3 - Photo of Valmont Power Plant and Eastern Transmission Loop

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Components and Layout The electric grid consists of both high voltage transmission lines and medium voltage distribution lines. Transmission lines are used to deliver electricity over large distances, taking it from where it is generated and delivering it to substations located close to and within the communities that are being served. Distribution lines then radiate and branch out from the substation to deliver electricity to individual customers. As illustrated in Figure 4, distribution lines can be thought of much like trees, with the large trunk that starts from the substation through which all electricity flows, referred to as the mainline, then branches that split off from the trunk, called secondaries, that distribute the electricity out in different directions and further branch off until you get to the leaves that are the individual customers. A single trunk/mainline can serve several thousand customers.

Figure 4 - Like trees, distribution lines start from the substation as a large trunk that then branches off into smaller lines, where each leaf can be considered an individual customer.

Draft – April 2026

Draft – April 2026 Today, power from the transmission loops on the east and west is brought into six substations that then serve Boulder. From these substations there are more than 30 individual distribution mainlines that provide power to residents and businesses within the city (See Figure 5). A subset of these lines also serve areas outside of the city limits.

Figure 5 - Illustration of the distribution lines serving the City of Boulder, including lines that serve both within (gray shaded area) and outside of the city limits.

Overhead Verses Underground Construction The early build out of the electric grid was overhead, with lines attached to wood poles or steel structures. It wasn’t until the late 1960s that utilities like Fort Collins began experimenting with underground construction and it was not until the 1970s and 1980s that underground construction became a widespread practice. In 1971, Boulder set precedent becoming the first municipality in Colorado to pass an ordinance requiring newly installed distribution lines to be constructed underground. Legacy overhead infrastructure has largely been maintained overhead, unless transitioned from overhead to underground during redevelopment, to make space for roadway expansion, or as funded by individual customers. Cumulatively, Boulder has an

Draft – April 2026 estimated 165 miles of distribution line and roughly 71% of those lines are constructed underground. Transmission is far more costly and complex to construct underground due to the larger cable size and spacing requirements. Additionally, a fault on a transmission line can impact tens of thousands of customers, so the ability to repair quickly becomes increasing important. Thus, except in dense urban areas like Denver, transmission lines have continued to be built overhead. This is true of utilities throughout the state, not just Xcel. For Boulder, only a very small segment of transmission line runs underground.3 In 1970, Public Service Company introduced the so-called 1% undergrounding program as a compensatory offering to communities with which it had a franchise. Through the program, Public Service would transition overhead lines to underground in the public right of way at the request of a franchise community at no cost to the community up to the equivalent of 1% of the annual revenues they collected from customers in the community. This program continued when Public Service merged with Southwestern Public Service Company to form New Century Energies in 1995 and again when New Century Energies merged with Northern States Power Company to form Xcel Energy in 2000. Boulder accessed this program from 1970 until the franchise expired in 2010 for a total of $17.5 million in undergrounding investments. When the city went back under franchise with Xcel in 2021, the city again gained access to the 1% program. As a result of the city’s settlement with Xcel on municipalization, Xcel made available makeup funds for the 10 years the city was out of franchise in addition to the forward looking 1% accruals. This resulted in $17.6 million worth of undergrounding projects completed from 2021 through 2025.

Utility-Ignited Wildfire Risk Live power lines faulting or failing have always been a hazard and potential source of wildfire. It is the last two decades, however, that have led to a material change in understanding of risks and consequences of utility-ignited wildfire. “The only real mistake is the one from which we learn nothing.” Henry Ford

Deadly Fires The October 2007 Southern California fire season was a historically significant event, with October fires burning nearly 1 million acres, causing over $2.39 billion in damage, and forcing the evacuation of 1 million people—at that time the largest in California

3 The transmission line that connects to the downtown Boulder Terminal substation from the west was

undergrounded from Mapleton Mobile home part to substation.

Draft – April 2026 history. Driven by severe drought and extreme Santa Ana winds, the fires brought realization to the threat posed by climate change and urban growth into the wildlands. The most destructive of the 2007 fires was the merged Witch and Guejito Fires, which resulted in two fatalities, the destruction of more than 1600 structures and estimated damages of more than $1 billion. Both fires were sparked by arcing power lines. The power line that caused the Witch Fire was found to have shorted three times in three hours, yet the utility did not cut power to it for six hours.5 These fires also changed the course of utility wildfire liabilities when the California Public Utilities Commission ruled that San Diego Gas & Electric had not trimmed back trees as state law requires. In August 2017, the administrative law judges ruled that the utility did not reasonably manage its facilities and that the wildfires were not outside of its control. Therefore, they ruled that the utility could not pass its uninsured costs along to its ratepayers. As global climate change has continued to drive warming and ecological changes, the wildfire risks that were first realized in Southern California, have now spread throughout the western United States, with several of the most destructive fires of the past two decades linked to utility infrastructure. Some of the most notable include: Camp Fire, California The November 8, 2018, Camp Fire is the deadliest and most destructive wildfire in California history to date. The fire began when hardware on a poorly maintained Pacific Gas and Electric Company (PG&E) transmission line in the Feather River Canyon failed during strong winds.6 Those winds drove the fire through the communities of Concow, Magalia, Butte Creek Canyon and Paradise, causing 85 fatalities, destroying over 18,000 structures and resulting in an estimated $16.5 billion in damages. PG&E filed for bankruptcy in January 2019, citing expected wildfire liabilities of $30 billion, and on June 16, 2020, they pled guilty to 84 counts of involuntary manslaughter. Lahaina Fire, Hawaii On August 8, 2023, intense winds knocked down multiple utility poles, leading to power outages impacting more than 12,000 customers across Maui. While attempting to reenergize, a downed power line sparked a brush fire on the northeast side of Lahaina and spread quickly. By the time the fire was extinguished 102 people were confirmed dead and more than 2200 structures were destroyed, including most of historic Lahaina,

6 PG&E’s transmission infrastructure was of similar vintage to the Xcel’s transmission infrastructure west

of Boulder.

Draft – April 2026 with damages estimated at close to $6 billion. Hawaiian Electric agreed to pay $2 billion of the $4 billion settlement for their role in the fire.

Figure 6 - PG&E transmission line towers near the spot where the Camp Fire began (credit Josh Edelson/AFP-Getty Images).

Smokehouse Creek, Texas Panhandle The February 26, 2024, Smokehouse Creek Fire became the largest in Texas history, burning more than a million acres (1654 square miles). The fire was caused by a downed power line from a broken Xcel-owned utility pole. The fire led to 2 human deaths and the death of more than 15,000 cattle, devastating the agricultural industry. Over 500 structures were destroyed and losses are estimated at more than $1 billion. In December 2025, the State of Texas filed suit against Xcel to recover over $1 billion in economic damages. The trial judge has since issued a temporary injunction, ordering Xcel to replace damaged wooden electric distribution poles and inspect at least 35,000 poles per year. Eaton Fire, California The Eaton Fire began on the evening of January 7, 2025, in Eaton Canyon in the San Gabriel Mountains. Powerful Santa Ana winds drove the fire into foothill communities, particularly Altadena. The fire killed at least 19 people and destroyed more than 9,000 buildings, becoming the fifth deadliest and the second most destructive wildfire in California history. The U.S. Justice Department has determined the cause to be high tension power lines operated by Southern California Edison.9

9 The so-called ghost line had last been used more than 50 years prior but is believed to have

experienced a momentary surge of electricity.

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Risk Factors These deadly fires boil down to three common denominators: • • •

Climate-driven drought and extreme winds; Increased consequence of wildfire due to urban growth into wildland areas; and Aging and undermaintained electric utility infrastructure.

Climate Change Boulder, like the western United States as a whole, is realizing the acute effects of global climate change in the form of more frequent drought, increasingly warmer and dryer winters and weather extremes. Already, Boulder has realized a near doubling in extreme heat days and a seven-fold increase in fire risk days. (see Table 1) As discussed, the evolution of the electric grid resulted in the construction of hundreds of miles of overhead high voltage power lines running through forests and grasslands to carry electricity from where it is generated to city gates. While it has always been true that a spark from a power line could start a fire, the risk grows as the areas these lines run through become increasing stressed by chronic drought and disease. Similarly, it has always been windy in Boulder, but the strongest and most destructive winds are typically in the winter months. When pole snapped or power line broke free in high

Draft – April 2026 winds in the past, there was likely also snow on the ground. Today, winters are increasingly dry creating the perfect recipe for wildfire. Table 1 - Effects of climate change on indices of fire risk and extreme weather showing change over historic baseline and forecasted projections based on climate science. (source City of Boulder Climate Action Plan)

Indicator (per year) Days over 95F Average Drought Days Extreme Precipitation Events Heat Wave Peak High Fire Risk Days

Historic Baseline

Today (Current)

2030 Projected

2050 Projected

28+

42+

151+

168+

12+

96F

98F

101F

103F

116

192+

230+

Wildfire Consequence Compounding the increased potential for utility-ignited wildfire is the increased consequence of wildfire due to exurban growth. As density of human-built structures in or adjacent to wildland areas increased, the likelihood of structures becoming involved in the fires has also increased. Once structures become involved, the intensity of the fire will grow making it more dangerous and challenging to combat. Once high intensity fires reach the urban environment, urban conflagration can ensue with devastating impact. Such was the case with the 2012 Waldo Canyon Fire and more recently the Marshal Fire. Infrastructure Age Generally, the average useful life of powerlines is more than 50 yeas for underground lines and more than 70 years for overhead; the useful life represents the timeline before a full rehabilitation is necessary, noting that individual components may require replacement sooner. Some of the infrastructure serving Boulder dates back more than a century. This issue is not unique to Boulder or to Xcel Energy. It is a challenge faced not just by the utility industry, but also by local and state governments – massive amounts of infrastructure were constructed during high growth periods that are now harder and more costly to replace. Tight budgets result in deferral of maintenance. As long as equipment keeps working or can be patched, it is kept in service well past its rated useful life. As the infrastructure continues to age, the deferred maintenance balance

Draft – April 2026 grows, and it becomes that much harder to catch up and the equipment is that much more likely to fail in catastrophic ways.

Boulder’s Utility-Ignited Wildfire Risk and Mitigation Impact One of Boulder’s great treasures is the open space and wildland areas that surround it. These beautiful and natural landscapes, however, place Boulder among the top wildfire risk communities in the country. As illustrated by the state’s wildfire risk map of the Boulder area (Error! Reference source not found.) wildfire risk is particularly prevalent along the city’s western and northern perimeters.

Figure 7- Boulder wildfire risk map illustrating the fire risk along the perimeter of the city. Red represents the highest risk areas, followed by orange and then yellow.

Today, new electric power infrastructure is designed to mitigate the potential for fire ignition. Thicker and taller poles increase clearances between wires, reducing vulnerabilities to wind and snow loading, and line-to-line contact. Covered wire, often referred to “tree wire,” protects against faults and sparks. Improved fault detection and safety devices de-energize lines more quickly when a fault occurs. It is the infrastructure constructed to the standards of the last century that poses the most significant risk, and the same wildland areas that present the greatest wildfire risk overall are also the areas where some of Xcel’s oldest infrastructure can be found. This is not just true of Boulder. Similar risks exist throughout Colorado; however, Boulder is amongst the most 16

Draft – April 2026 concerning because of the locations of electric equipment and the prevalence of extreme winds. While Xcel is working to replace infrastructure in high-risk areas, it will be years and even decades before the wildfire risks associated with their equipment is mitigated. In the interim, Xcel has joined utilities throughout the western United States in wildfire safety operations, which includes two components: 1. Public Safety Power Shutoff (PSPS): Where power lines that serve in high-risk areas are proactively de-energized. Xcel’s Criteria: Top 1% of historical wind speeds + <15% humidity + fuel conditions (dryness and amount of vegetation) 2. Enhanced Power Safety Settings (EPSS): Where the sensitivity of the system is increase so that power remains on but will go off and stay off if a fault occurs. Xcel’s Criteria: Red Flag Warning For extreme weather and fire risk events, Xcel will identify power lines that are situated within wildland areas that pose a potential ignition risk based on meteorological forecasts and modeling. Based on the modeled risk, the line will either be proactively de-energized (PSPS) or placed in EPSS mode. Xcel conducted its first PSPS event in Colorado in April 2024, which had widespread impact on Boulder and surrounding areas of Boulder County. Also beginning in 2024, Xcel began to use EPSS and, as a result, throughout 2024 and 2025, Boulder experienced multiple wide-impact EPSS outages, and this trend has continued into 2026. In December 2025, Xcel implemented its second and third PSPS events on the 17th and 19th, respectively. While not impacting Boulder, another PSPS was conducted by Xcel in January 2026, focused on northern Colorado, and in February 2026, Black Hills Energy conducted its first PSPS in areas near Pueblo. On March 14, 2026, the Boulder community was again impacted by a PSPS. Xcel has also conducted multiple PSPS events in its Texas and New Mexico service territory. While Black Hill is the only other Colorado utility to use PSPS to date, EPSS has been and continues to be a mitigation approach used by most Colorado utilities. Because of ongoing drought and the fact that Boulder is prone to some of the highest wind speeds in the country, Boulder has been included in all but one of Xcel’s Colorado PSPS events and had EPSS in place for extended periods of the year. While the risk of wildfire ignition is low within the urban center, a portion of the power lines that serve residents and businesses in Boulder either emanate from of extend to areas outside of the city that are a wildfire concern as highlighted in Figure 8. De-energizing the lines in these areas has necessitated the entire line to be turned off, causing extended outages

Draft – April 2026 for large areas inside the city limits even though most of the area within the city limits is considered low risk for wildfire ignition.

Figure 8 - Xcel system map highlighting electric infrastructure located in highest wildfire risk areas.

Xcel’s 2025-2027 Wildfire Mitigation Plan In August 2025, the Colorado Public Utilities Commission formally approved Xcel’s 2025-2027 Wildfire Mitigation Plan (WMP), authorizing nearly $2 billion dollars in wildfire mitigation investments. The City was a party to the unanimous, comprehensive settlement in the case. The WMP and associated settlement outline significant investments in the Boulder area that, once implemented, will materially reduce the impacts of PSPS and ESPP and the threat of utility-ignited wildfire. Investments will include targeted undergrounding; line sectionalization; rebuilding to wildfire standards; and increased deployment of weather stations, infrared cameras, and fault detection. While the precise financial investment planned for the Boulder area is still evolving, the

Draft – April 2026 City estimates that capital investments could approach $0.5 billion. Projects already underway include: [This section would be updated based on additional information developed over the course of 2026. The initial list of projects is provided here to help give context to the community’s current experiences and how planned Xcel investments will reduce impacts.] North Boulder Undergrounding Among the most significant wildfire concerns is the overhead line that starts in downtown Boulder, heads north along 28th Street and then continues north along Highway 36 towards Lyons. A spur from this line also heads into the foothills along Lee Hill Drive. This line provides power to a significant portion of north Boulder, including high speed traffic intersections and business areas, as illustrated in Figure 9. Xcel will underground roughly 5.5 miles of this line, and plans to begin construction during 2026. Once complete, only the foothills areas served by the Lee Hill Drive section of the line would remain subject to PSPS.11 Long-term, Xcel is expected to rebuild the line in the foothills areas to meet wildfire mitigation standards, further reducing the need for PSPS.

Figure 9 - Wildfire risk associated with Xcel's powerline along Highway 36 and extending up Lee Hill Drive. The area circled generally represents the areas impacted by PSPS for this powerline.

11 While there is no guarantee that PSPS would never be utilized, the probability that it would be

necessary once the line is undergrounds is so low as to be considered negligeable.

Draft – April 2026 Northwest Boulder Sectionalization and Hardening While most of the powerline serving the highlighted area shown in Figure 10 is inside the lower risk urban core, small sections of the line reach up into the foothills. Xcel is evaluating solutions to include sectionalizing and rebuilding the sections in the foothills to wildfire standards.

Figure 10 – Wildfire risk associated with Xcel’s power line serving areas of northwest Boulder. The area circled generally represents that impacted by PSPS and EPSS events.

West Central Sectionalizing, Undergrounding and Rebuild The areas west of Broadway, generally between Mapleton and Upper Chautauqua have been heavily impacted by both PSPS and EPSS outages. The electric infrastructure in this area is amongst the oldest and most concerning due to the rugged terrain the power lines run through up Sunshine Canyon. As illustrated in Figure 11, both the transmission line that carries power to Boulder from the west to the Sunshine substation and distribution lines that then delivers power from the substation to customers inside and outside the city limits are located in the highest risk wildfire risk area. Xcel has completed design and is final permitting to begin rebuilding the transmission line. Xcel is also expected to make improvements to the distribution line during 2026, which could include sectionalization, automated switching to allow for rerouting power from a lower risk line, or undergrounding. In addition to the wildfire risk shown in the Figure, one of the power lines that originates from the Sunshine substation also serves Chautauqua and Flagstaff. This is the same line that powers University Hill and areas generally on the south side of Canyon Boulevard. During 2025, Xcel completed the second phase of underground at Chautauqua, removing the main wildfire concern. Xcel will use sectionalization to isolate 20

Draft – April 2026 the section that serves up flagstaff to reduce the impacts of PSPS and EPSS until the Flagstaff area can be reconstructed to wildfire standards.

Figure 11 - Wildfire risk associated with Xcel's powerlines along Sunshine Canyon. The area circled generally represents the area impacted by PSPS and EPSS events.

South Boulder Undergrounding and Sectionalization For south Boulder, there are three main areas of wildfire risk concern – 1) on and surrounding the federal laboratory property, 2) areas along the east/southeast city perimeter such as CU South, and 3) and the Shanahan Ranch/Marshal area. These are illustrated in Figure 12 and Figure 13. Xcel plans to underground the power lines in all three of these areas. Prior to the March 14 PSPS, Xcel completed installation of equipment to reduce customer impacts for the Marshal line. This allowed them to maintain power for the Shanahan Ridge neighborhood.

Draft – April 2026

Figure 12 - The wildfire risk associated with Xcel's power lines serving areas of south Boulder. The highlighted areas show where the line runs through high wildfire risk areas. PSPS impacts are the areas generally between and to the north of the highlights.

Figure 13 - The wildfire risk associated with Xcel’s power lines entering South Boulder from the Eldorado Springs/Marshall area. The highlighted area shows the area generally impacted by PSPS.

East Boulder Undergrounding, Sectionalization and Rebuild Wildland areas along Boulder’s eastern perimeter also pose a wildfire threat, particularly for neighboring communities as illustrated by Figure 14 and Figure 15. Xcel is in final permitting and expects to begin construction in late April or early May 2026 for the first undergrounding project in this area, which will be along 75th Street between Lookout and the city’s Water Resource Recovery Facility located just south of Jay Road. [Staff are working with Xcel to understand the full scope of other work planned for this area in addition to the undergrounding project on the 75th. This will likely include a combination of additional undergrounding, sectionalization and overhead rebuild.]

Draft – April 2026

Figure 14 - Wildfire risk associated with Xcel's power lines in grassland areas in eastern Boulder.

Figure 15 - Wildfire risk assocated with Xcel's power lines in grassland areas in eastern Boulder.

Draft – April 2026

Other Reliability Concerns While PSPS events have been the most disruptive to the community since multiple areas are impacted at once and outages tend to be longer, the community has also experienced outages unrelated to wildfire safety operations. Underground Cable Failures In October 2025, the underground cable serving the west downtown failed. The pair for this line failed during the 2013 floods and was never replaced. While Xcel was able to restore power to customers, the solution is temporary and precarious as summer cooling demands approach.13 A second underground cable and required emergency repair in February 2026 along Linden Avenue near Maxwell Reservoir. While Xcel was able to reroute power to residential customers in the area, the city’s hydroelectric facility at Maxwell Reservoir was left without grid-connection for nearly two months. While this did not threaten city water supply, there were lost revenues associated with inability to deliver power from the city’s generation equipment. In addition to these two lines that required emergency replacement, there have also been several other underground cable failures that required repair. Staff believe that most if not all of the outages are associated with circa 1970s-1980s installations. Wildlife Contact A common form of outage in Boulder is animal contact, either birds and squirrels shorting out overhead equipment or snakes and rodents getting into cabinetry and underground equipment. In recent years, the Shanahan Ridge neighborhoods experienced excessive outages for this reason. City staff became aware of this issue in 2024 and were able to work with Xcel to get guards installed around equipment to mitigate future occurrences. Vegetation In many of the older neighborhoods, power lines were run along back-of-lot easements, rather than in the public right of way which is now the more common practice. Maintaining vegetation around lines in these areas is more challenging due to access limitations and periodic resistance from property owners. Additionally, many mature trees have become less stable due to age, drought and disease. Many outages have been caused by limbs brushing lines as well has as large limbs and entire trees collapsing on lines during high winds or heavy precipitation. While Xcel will be conducting extensive vegetation management during 2026, vegetation issues tend to recur over time unless trees are fully removed or power lines are moved underground.

13 Permits have been issued and the repair is underway.

Draft – April 2026

Disparate Impacts Based on Xcel’s 2025 data and as shown in the heat map (Figure 16), Boulder had the worst reliability in terms of outage frequency, which is measured as the percent of customers experiencing 6 or more outages. While Boulder was not the worst in terms of outages lasting more than 18 hours, the percentage of customers in Boulder that do experience extended outages is far greater than many other front range communities.

Figure 16 - Quality of Service Heat map showing areas where Xcel customers experienced six or more outages during 2025.

More granularly, different areas of Boulder have very different experiences in terms of power reliability. Even within individual neighborhoods, individual neighbors can have very different experiences. This is because of how individual power lines traverse through the city. Different properties on the same block can be served from two or more completely different mainlines. Using geographic information about the electric system that is available to the city through its partnership with Xcel, the community can be divided into reliability zones. An illustrative map is included as Figure 17.

Draft – April 2026

Figure 17 - Illustrative reliability zone map where each identified area represents customers served from a common power line.

[As part of the 2026 project this map will be further refined with reliability and resilience scores assigned to each group. This analysis will include an equity overlay.]

Xcel Planned Investments Beyond Wildfire Mitigation [Staff are working with Xcel review planned and anticipated investments.]

Draft – April 2026

Asset Health and Reliability Investments [This section would include ongoing maintenance investments, including end of life equipment replacement and vegetation management.]

Substation Rebuild and Expansion [This section would discuss plans and timelines, to include the planned reconstruction of the downtown substation, expansion of and improvement to existing substations, and potential a new substation(s).]

Capacity Expansion [This section would include plans to upgrade equipment to address current capacity constraints on the system that present barriers to solar installations, new development, electric vehicle charging stations, and building electrification.]

Community Engagement [What we heard.]

Policy Roadmap [This section will be replaced with the final policy recommendations adopted by council at the end of the project.] To support development of the Power Resilience Roadmap, staff will evaluate a set of potential policy pathways that reflect the range of roles the City can play to improve reliability and reduce community impacts from power outages. These pathways are not mutually exclusive and are intended to provide a structured framework for analysis, community input, and future Council decision-making. 1. Grid Hardening and Infrastructure Investment Focus on reducing outage frequency and wildfire risk through physical improvements to the electric system. Potential strategies may include: • Accelerated undergrounding of distribution lines, including evaluation of costsharing models; • Replacement of aging infrastructure and targeted system upgrades in high-risk areas; • Increased sectionalization to limit the geographic extent of outages; and • Expanded vegetation management and right-of-way improvements.

Draft – April 2026 This pathway will include assessment of how the City can influence or accelerate investments by Xcel Energy through existing agreements, regulatory engagement, partnership and shared investment. 2. Distributed Energy and Local Resilience Solutions Focus on reducing the impact of outages by enabling localized, decentralized energy resources. Potential strategies may include: • Deployment of solar + battery storage systems for homes, businesses, and critical facilities; • Development of microgrids to support critical infrastructure and communityserving facilities; • Incentive programs, rebates, or financing mechanisms to expand access to backup power; and • Exploration of neighborhood-scale or community energy solutions. This pathway is particularly important for supporting continuity of essential services and enabling resilience during extended outages. 3. Community Preparedness and Resilience Capacity Focus on strengthening the community’s ability to prepare for, respond to, and recover from power outages. Potential strategies may include: • Expansion of community resilience hubs to provide safe, powered locations during outages; • Targeted support for medically vulnerable residents and those with limited mobility; • Business continuity resources and support for small businesses; and • Public education, communication tools, and emergency preparedness programs. This pathway emphasizes near-term, community-centered actions that can reduce harm regardless of outage cause. 4. Regulatory, Legislative, and Legal Strategies Focus on advancing policy and regulatory changes to improve accountability, performance, and investment in the electric system. Potential strategies may include: • Engagement with state regulatory bodies (e.g., Public Utilities Commission) on reliability standards and utility performance; • Evaluation of legal strategies related to service reliability and risk mitigation; • Advocacy for state legislation to support resilience investments and community protections; and

Draft – April 2026 •

Use of franchise agreement provisions to establish expectations and accountability mechanisms.

This pathway will explore how Boulder can use its voice and authority to shape broader system outcomes. 5. City-Led Investment and Critical Infrastructure Resilience Focus on ensuring continuity of City operations and protection of essential public services. Potential strategies may include: • Backup power and resilience upgrades for critical City facilities; • Integration of resilience into capital planning and infrastructure investments; • Coordination with regional partners, including Boulder County and special districts; and • Strategic investments to support emergency response and recovery operations. This pathway ensures the City is leading by example while maintaining essential services during disruptions. 6. Equity-Centered Resilience Strategies Equity will be integrated across all policy pathways, with a focus on addressing disparities in outage impacts and access to resilience resources. Key considerations include: • Prioritizing investments in communities with higher outage risk and lower adaptive capacity; • Expanding access to backup power and financial assistance programs; • Partnering with community-based organizations to co-develop solutions; and • Ensuring engagement processes elevate the voices of those most impacted.

Conclusions [This section would summarize the next steps.]