20260416Staff Comments.pdf

RECEIVED
April 16, 2026
JEFFREY R. LOLL IDAHO PUBLIC
DEPUTY ATTORNEY GENERAL UTILITIES COMMISSION
IDAHO PUBLIC UTILITIES COMMISSION
PO BOX 83720
BOISE, IDAHO 83702
[phone]
IDAHO BAR NO. 11675
Attorney for the Commission Staff
BEFORE THE IDAHO PUBLIC UTILITIES COMMISSION
IN THE MATTER OF AVISTA )
CORPORATION'S APPLICATION FOR ) CASE NO. AVU-E-25-15
APPROVAL OF THE 2026 WILDFIRE )
MITIGATION PLAN )
COMMENTS OF THE
COMMISSION STAFF
COMMISSION STAFF ("STAFF") OF the Idaho Public Utilities Commission
("Commission"), by and through its attorney of record, Jeffrey R. Loll, Deputy Attorney
General, submits the following comments.
BACKGROUND
On December 9, 2025, Avista Corporation ("Company") applied ("Application") to the
Commission requesting an order approving its 2026 Wildfire Mitigation Plan ("2026 WMP")
and processed under Modified Procedure. Application at 6-8. The Company previously had filed
its 2020 WMP, 2023 WMP, and 2024 WMP with the Commission in various cases for review.I
Additionally, the Company requested the Commission issue an errata to Order No. 36774
aligning the ordering language related to notices under Idaho Code § 61-1804(2) with Staff s
recommendation in Case No. GNR-E-25-02. Application at 6.
1 Case No.AVU-E-20-05,2020 WMP filed as part of a request for a deferral for wildfire mitigation expenses. Case
No.AVU-E-23-01,2023 WMP filed as part of a general rate case.Case No.AVU-E-25-01,2024 WMP filed as part
of a general rate case.
STAFF COMMENTS 1 APRIL 16, 2026

Lastly, the Company requested the Commission clarify within its order whether the
Company can file its updated WMP for the Commission's annual review on or about November
I"of each year going forward. Application at 8.
On December 22, 2025, the Commission issued an errata to Order No. 36774 in Case No.
GNR-E-25-02, aligning the ordering language to Staff s recommendation about notices.
On January 6, 2026, the Commission issued a Notice of Application and Notice of
Intervention Deadline. Order No. 36901. On January 29, 2026, the Commission granted
intervention to PotlatchDeltic Forest Holdings, LLC. Order No. 36888.
STAFF ANALYSIS
Pursuant to Idaho Code § 61-1804, Staff reviewed the Company's 2026 WMP for
compliance and believes it meets the requirements of the Wildfire Standard of Care Act
("WSCA"),Idaho Code § 61-1803, Order No. 36774 and the Commission approved WMP
Guidelines, detailed in Exhibit No. 1 to that Order("Guidelines"). Staff recommends the
Commission issue an order that(1) approves the Company's 2026 WMP, and(2) clarifies that
the Company may file its updated WMP for the Commission's annual review on or about
November I"of each year going forward. Although Staff believes that the Company's 2026
WMP meets the relevant requirements, Staff suggests the Company include additional items in
future WMP filings as discussed below.
I. 2026 Wildfire Mitigation Plan
The Company requested the Commission issue an order approving its 2026 WMP,
finding that it complies with Order No. 36774, as well as the WSCA, finding it meets the
minimum requirements stated in Idaho Code § 61-1803; is consistent with public health, safety
and welfare; is feasibly implemented; and adequately minimizes wildfire risk and proposes to
respond to wildfires that do occur. Application at 8. Staff believes that the WMP substantially
meets the requirements; however, Staff provides recommendations for future WMP filings.
Cost Forecasts
In its 2026 WMP, the Company inadvertently excluded certain operations and
maintenance ("O&M") expenses for a few WMP categories in Appendix B. Company's
STAFF COMMENTS 2 APRIL 16, 2026

Response to Staff Production Request No. 33. However, in its response, the Company provided
an attachment containing corrected cost forecasts for Idaho and Washington. Id.
For 2026 in Idaho, the Company forecasts $12.1 million in capital investments and$7.2
million for O&M expenses. Company's Response to Staff Production Request No. 33
Attachment A. The primary capital expenditures are the Company's Transmission Grid
Hardening Program and the Wildfire Detection Cameras installations, forecasted to be $3.5
million and $2.5 million, respectively.Id. The Company's primary O&M expense is its Risk
Tree Reduction program, forecasted to be $5.6 million.Id.
For 2028 through 2030, the Company's forecasted capital expenditures in Idaho
increased compared to 2026 and 2027. The increase is driven by planned investments in
Distribution Grid Hardening located in high-risk areas. Id. The Company's forecasted O&M
expenses for these years are relatively stable, with an average forecast of$7.9 million per year.
Id.
In Table No. 1 below, Staff summarized the Company's Idaho cost forecasts.
Table 1: Idaho Cost Forecasts Summary
$ in Category 2026 2027 2028 2029 2030 5-Year
`OOOs Total
Grid Hardening $ 4,200 $ 7,200 $15,400 $ 27,600 $ 20,900 $ 75,300
ID Operations and $ 3,460 $ 3,200 $ 2,600 $ 2,200 $ 2,200 $ 13,660
Capital EmergencyRes onse
Situational $ 4,400 $ 2,500 $ 3,300 $ 1,500 $ 1,500 $ 13,200
Awareness
TOTAL CAPITAL $ 12,060 $12,900 $21,300 $ 31,300 $ 24,600 $ 102,160
Grid Hardening $ 220 $ 220 $ 220 $ 220 $ 220 $ 1,100
Operations and $ 44 $ 44 $ 44 $ 44 $ 44 $ 220
ID Emergency Response
Situaonal
O&M Awareness $ 177 $ 221 $ 235 $ 260 $ 297 $ 1,190
Vegetation $6,784 $6,997 $ 7,123 $ 7,419 $ 7,445 $ 35,768
Management
TOTAL O&M $ 7,225 $ 7,482 $ 7,622 $ 7,943 $ 8,006 $ 38,278
Internal Wildfire Mitigation Labor
While reviewing the Company's cost forecasts, there was no line item that distinguished
internal labor for wildfire mitigation. Staff believes a separate line item for internal wildfire
STAFF COMMENTS 3 APRIL 16, 2026

mitigation labor should be included in each WMP to identify dedicated labor expenses related to
wildfire mitigation and to allow Staff to track labor costs over time. The Commission previously
ordered Idaho Power Company and Rocky Mountain Power to include internal labor in the cost
forecasts in their WMPs. Order Nos. 37004 and 36405. Staff recommends the Commission
direct the Company to add a line item to its cost forecasts for internal wildfire mitigation labor
for future WMP filings to assist Staff in its review and to provide consistency in the WMPs of
Idaho's investor owned utilities.
Targets within WMP
The Company identified targets to be met for each major cost category within its WMP:
Grid Hardening, Operations and Emergency Response, Situational Awareness, and Vegetation
Management. Company's Response to Staff Production Request No. 33 Attachment A. Staff
appreciates the Company's identification of targets for each program; this information assisted
Staff in evaluating the feasibility of the proposed 2026 WMP.
Comparison to 2024 WMP
The Company's 2024 WMP did not separate Idaho and Washington forecasted
expenditures. 2024 WMP at 10. In that WMP, the Company provided its actual expenditures at
year end for 2020 through 2023 and forecasted expenditures for 2024 through 2029. Id.
In its 2024 WMP, the Company forecasted 2026 capital expenditures to be $60.3 million
and O&M expenses to be $13.8 million. Id. The Company had planned to increase its strategic
undergrounding and steel pole replacement investments.
Overall, in Idaho and Washington for 2026, the Company forecasted$15.9 million less in
capital expenditures and $4.2 million more in O&M expenses in the 2026 WMP compared to the
2024 WMP.
II. Geographical Risk Assessments
Idaho Code § 61-1803(3)(a) and the Guidelines require all WMPs to include a
description of the Company's wildfire risk assessment and a map of identified risk areas. The
Company's methodology incorporates a mathematically coherent framework for wildfire risk
calculation, strong and diverse data inputs, statistical model validation, and development of
STAFF COMMENTS 4 APRIL 16, 2026

practical wildland urban interface ("WUI")maps that are updated every 2 years. Staff believes
the Company generally followed sound quantitative and qualitative modeling approaches to
assess wildland fire risks to identify geographical areas with heightened risk. However, Staff
believes the Company's Geographical Risk Assessment section in the WMP has several
limitations, such as: (1) nomenclature issue with the WUI maps compared to industry standard,
(2) lack of descriptive narrative details of data inputs and methodology for risk modeling within
the 2026 WMP, and(3) lack of several input parameters in the risk assessment techniques used
by the Company. These topics are discussed in detail in the following sections.
WUI Risk Map
The Company created a risk map that the Company refers to as the WUI map. However,
there is a standard industry map of the WUI that is different than the Company's risk map, as it
doesn't consider the same factors.2,3 To avoid confusion from industry-standard WUI maps,
Staff encourages the Company to change the name of its risk map.
Risk Model
Staff observed that the Company's 2026 WMP does not include a detailed description of
the wildfire risk assessment or model used to guide wildfire mitigation activities, in accordance
with the WSCA and the Guidelines. The 2026 WMP only shows outputs from the modeling
process. 2026 WMP at 9-10. In its comments, the Idaho Department of Lands ("IDL")
highlights this issue and requests that the Company include a detailed narrative that covers data
inputs and model methodology. IDL Comments at 1. Staff concurs with the IDL's
recommendation. Staff was able to verify the data inputs and methodologies through the
Company's response to Staff Production Request Nos. 15-17. Because this information is
necessary for the approve the WMP, Staff recommends the Commission direct the Company to
provide a detailed methodology description of the risk modeling and determination of
geographical risk areas as a part of future WMP filings rather than through responses to
discovery.
2 The Federal Emergency Management Agency("FEMA")defines WUI as the zone of transition between
unoccupied land and human development.It is the line,area or zone where structures and other human development
meet or intermingle with undeveloped wildland or vegetative fuels.
3 FEMA has publicly available WUI maps and data sets.https:Hgis-fema.hub.arc isg com/pages/wui-awareness.
STAFF COMMENTS 5 APRIL 16, 2026

The 2026 WMP indicates that the Company is transitioning from its in-house Fire Risk
Index("FRI") approach, as discussed in the Situational Awareness section, to a next-generation
wildfire risk modeling technique with the vendor, Aerospace Technical Services ("ATS"). 2026
WMP at 12. The new modeling framework should incorporate asset fragility, ignition
probability, consequence analysis, and economic impact modeling to quantify cost-benefit ratios
of mitigation efforts. Staff believes the results of the next-generation risk modeling should be
available in the Company's future WMPs.
Risk Assessment Methodology
Staff believes the Company's risk modeling contains several limitations, including: (1)
missing and de-weighted driver of ignitions, (2)biased exposure to populated areas, and(3)
limited asset and attachment visibility, which are discussed in the next section. Based on Staff s
assessment, the Company should consider including the following in wildfire risk modeling and
assessments in future WMP filings:
1. Take necessary steps to incorporate the following input parameters as a part of its new
modeling approach, as applicable:
a. Asset fragility& ignition probability (per asset/class);
b. Third-party pole attachments; and
c. Lightning density as a dynamic input.
2. Augment Housing Unit Impact("HUI") data with critical facility layers, including but
not limited to healthcare organizations, airports, traffic controls, communication systems,
etc. (2026 WMP at 75), vulnerable populations (2026 WMP at 49), and community
recovery capacity to refine wildfire consequence modeling per Electric Power Research
Institute ("BPRI") guidance on exposure and vulnerability integration;4,5 and
3. Publish confidence bands or uncertainty bands around risk scores (e.g.,by input variance)
to inform decision risk and avoid false positives at the hexagonal or equivalent unit cell
boundaries.
4 hLtps:Hrestservice.epri.com/publicdownload/000000003002022665/0/Product;Accessed: 04/02/2026.
5 hLtps://www.utilitydive.com/spons/epri-releases-study-of-wildfire-tools-to-proactively-assist-electric-
compan/718770/;Accessed:04/02/2026.
STAFF COMMENTS 6 APRIL 16, 2026

Key Strengths of the Company's Risk Modeling Methodology
Staff identified the following strengths in the Company risk-assessment methodology:
1. Clear Mathematical Structure and Actionable Granularity—In its risk modeling, the
Company defines: Wildfire Risk=Probability of Outage X Consequence. The fire spread
calculation framework is based on a geospatial granularity of 200-meter hexagonal shapes
across its territory, combining various inputs such as utility outage frequency, vegetation
exposure, construction type (such as, overhead or underground) datasets including Wildland
Hazard Potential ("WHP") and HUI from United States Forest Service ("USFS") and
localized customer feedback to quantify wildfire consequence. Dynamic modifiers (e.g.,
wind speed, wind gusts, relative humidity, Severe Fire Danger Index or"SFDI" and fire
preparedness) are updated every 2 hours and are applied to the sub-circuit sectionalizing
devices, which enables precise Fire Safety Mode ("FSM") and Public Safety Power Shutoff
("PSPS") actions and targeted hardening. 2026 WMP at 11-12 and Company's Response to
Staff Production Request Nos. 14-16.
2. Transparent Tiering and Planning—The Company has four statistically-defined wildfire tiers
or WUIs based on the calculated geographical risk scores: Low, Moderate, Elevated, and
Extreme. 2026 WMP at 10 and Company's Response to Staff Production Request No. 16.
Staff believes it is a clear, reproducible way to identify and drive long-term mitigation efforts
such as vegetation management, grid hardening, etc.
3. Calibration and Validation via Regressions and Back-casting The Company utilized simple
regression methods to identify the appropriate input variables within its model for fire
prediction and then created a back-casting model to compare predicted fire growth with
historical wildfires. Company's Response to Staff Production Request No. 16.
Gaps in the Company's Approach and Improvements to Consider
Staff also identified the following gaps in the Company's risk-assessment methodology
that should be addressed in future WMP filings.
1. Missing or de-weighted drivers of ignition:
a. Historic outage and ignition—The Company's statistical analysis found that there is
no significant correlation between historic outage data and utility ignitions -yet the
STAFF COMMENTS 7 APRIL 16, 2026

risk modeling approach applied outage as one of the fundamental variables for
calculating static risk. Company's Response to Staff Production Request No. 8.
b. Lightning was not modeled—The Company monitors lightning strike maps but it
does not incorporate lightning as an input to the risk calculation. Company's
Response to Staff Production Request No. 8. According to the existing literature,
lightning strikes are considered as one of the natural catalysts for both disrupting
electrical network operations and igniting fires. Staff believes lightnings should be
accounted for as a part of the risk modeling.6,7,8
2. Exposure bias to populated areas—The Company's strong reliance on HUI (potential number
of homes lost) can underweight remote high fuel areas, such as the Idaho Panhandle National
Forest. Company's Response to Staff Production Request No. 16. Staff believes that
although such forest areas may have fewer existing structures due to the abundance of
available fuel, fires could grow and cause large acreage to be burnt. Thus, Staff believes
using lower bias towards high fuel areas may potentially mask the operational threat to
transmission corridors in remote areas containing large amounts of fire fuel.
3. Limited asset/attachment visibility:
a. Third-party pole attachments—Third-party pole attachments are not considered in
risk modeling or wildfire risk mitigation efforts. The violations are addressed
opportunistically, instead of through wildfire-specific inspection. Company's
Response to Staff Production Request No. 19.
b. Material failure analysis—The Company does not typically perform material failure
analyses based on a routine. Such analyses are conducted by external experts for
post-wildfire events with privileged and confidential results only when an initial
investigation indicates a failure of the Company's facilities may have caused the
event. Company's Response to Staff Production Request No. 9. Staff believes this
approach limits data feedback to the modeling.
6 hLtps://www.mdpi.com/1999-4907/14/6/1146;Accessed: 04/06/2026.
hLtps:Hdocs.nrel.gov/docs/fy23osti/80746.pdf;Accessed: 04/06/2026.
8 hLtps://www.sciencedirect.com/science/article/pii/S1474034620300392;Accessed: 04/06/2026.
STAFF COMMENTS 8 APRIL 16, 2026

III. Preventative Actions and Programs
Idaho Code § 61-1803(3)(b) and the Guidelines require all WMPs to include discussion
of all the electric corporation's preventative actions and programs within the WMP. The
Guidelines require that the following sections be included: (1)public outreach and engagement,
(2) government outreach, (3) method of line design, (4) situational awareness and monitoring, (5)
infrastructure inspection and maintenance, (6) de-energization and line operation practices, and
(7)vegetation management. Staff discusses all the required preventative actions and programs in
the sections below.
The Guidelines also state that the Company may include other actions or programs, such
as system hardening strategies, workforce preparedness, and pilot programs. Id. at 3-4. Staff
discusses the Company's workforce preparedness in this section.
Workforce Preparedness
The Guidelines state that a WMP may include workforce P\preparedness as a
preventative program. Guidelines at 3. A robust workforce demonstrates that personnel possess
the skills and readiness to safely and effectively execute wildfire risk-reduction measures, such
as situational awareness, emergency response actions, and safe line operations. This approach
not only fulfills regulatory obligations but also strengthens operational resilience, reduces the
likelihood of safety incidents during wildfire season, and supports timely, coordinated responses
when conditions escalate.
The Company described its workforce training in Appendix D. It also provided the
training materials used and training completion data in responses to Staff Production Request
Nos. 20 and 21. Based on its review of the WMP and Company's responses to Staff Production
Requests, Staff believes the Company has met the requirements related to workforce
preparedness in the Guidelines. Not all of the data Staff needed to review on this topic was
included in the WMP. To assist Staff in future reviews, Staff recommends the Commission
direct the Company to provide copies of all wildfire related training as attachments and provide a
table identifying the role, number of people, training date (i.e., date, month, or quarter), and type
of training completed in future WMP filings.
STAFF COMMENTS 9 APRIL 16, 2026

IV. Public Outreach and Engagement
Idaho Code § 61-1803(3)(c) and the Guidelines require each WMP to describe how the
utility maintains community outreach and public awareness before, during, and after wildfire
season. Staff believes the Company's WMP meets the public outreach and engagement
requirement.
The 2026 WMP describes the community outreach efforts to educate customers about
wildfire risk and the Company's mitigation activities. The Company's community engagement
includes: (1)Avista Connections, (2) customer e-mails, (3) PSPS notifications (e.g., awareness,
preparedness, watch, warning execution, and restoration), (4)telephone town halls, (5)print
advertisements, and (6) community meetings. 2026 WMP at 66-67. The Company indicated it
will tailor communications using a mix of channels, including: e-mail, interactive voice response
calls, press releases, social media, outage map updates, and direct outreach. Id. Staff believes
the public outreach efforts are reasonable and consistent with Commission expectations.
Consistent with Staff s discussion in the Government Outreach section below, the Company
should consider identifying methods to expand public participation by partnering with federal,
state, local, and tribal organizations.
V. Government Outreach
Idaho Code § 61-1803(3)(d) and the Guidelines require each WMP include a discussion
of outreach and coordination with federal, state, tribal, and local officials and agencies regarding
wildfire preparedness and emergency response planning. Staff believes the Company's 2026
WMP satisfies these requirements.
The Company describes coordination efforts with federal, state, local, and tribal
governments, including partner forums, tabletop exercises, and coordinated planning activities.
2026 WMP at 58-65. However, the section does not identify the parties involved in the outreach.
The Company should consider specifying the federal, state, local, and tribal organizations with
which it coordinates,preferably in a table or appendix, for clarity. Staff notes that public
participation may increase when the Company partners with these organizations. Accordingly,
the Company should continue to identify opportunities to expand and increase public
participation.
STAFF COMMENTS 10 APRIL 16, 2026

Additionally, the Company has partnered with different agencies to implement mitigation
projects, called"Fuel Reduction Partnerships". 2026 WMP at 39-40 and Company's Response
to PotlatchDeltic Production Request No. 27. Staff suggests the Company provide more detailed
descriptions of each current and planned partnered project in future WMP filings.
VI. Method of Line Design and Grid Hardening
Idaho Code § 61-1803(3)(e) and the Guidelines require each WMP include a description
of the Company's methods of line design for new lines and planned system upgrades. Staff
believes the Company's approach for its grid hardening and line rebuilding is reasonable;
however, Staff recommends the Company include additional details in the future. Similarly,
Staff believes the undergrounding study and covered conductor study are reasonable justification
for the pilot projects that Company has started; however, Staff has suggestions for the Company
to consider in future WMP filings.
Grid Hardening
Staff assessed the Company's grid hardening efforts, such as the overhead to
underground conversion study and the covered conductor study. Staff identified several areas for
improvement, including lack of: (1) measurable targets for these projects, prioritized by wildfire
risk zones, (2) information regarding potential mitigation effectiveness in wildfire risk
reductions, and(3) comparative cost-benefit analysis ("CBA")between various grid hardening
strategies. Based on its analysis, Staff suggests the Company consider incorporating the
following in its grid hardening approach, in future WMP filings:
1. Provide short-term (3 to 5 year)measurable targets, such as, miles per year, feeders, WUI
tier mix, material standards (e.g., tree-wire vs. spacer cable, insulation thickness, tie/arm
hardware), and selection criteria derived from ATS (asset-level ignition probability,
monetized consequence) output, based on the reasonableness of costs across the
anticipated grid hardening efforts (e.g.,undergrounding, covered conductor, etc.).
2. Provide table(s) of mitigation effectiveness, including feeder-specific ignition risk
reductions (e.g.,utility caused ignitions per 100 miles of line, pre- and post-
undergrounding, etc.) and expected reliability improvement metrics (e.g., changes in
STAFF COMMENTS 11 APRIL 16, 2026

service interruption duration and frequency indexes on converted or upgraded segments,
restoration cost per event, etc.).
3. Provide comparative CBA for all grid hardening efforts, such as covered conductor,
selective undergrounding of segments, etc., to provide a ranking of risk reductions based
on benefit to cost ratios (`SCRs") across the total portfolio, not based only on one
specific mitigation approach.
4. Include asset-level ignition likelihood, including asset fragility, spark potential, local
weather, available fuel, etc., and then re-monetize the feeder-by-feeder grid-hardening
approach.
5. Include stochastic scenario optimization in wildfire consequence modeling (fat-tailed
events as outlined in Company's 2026 WMP Appendix C at 51) to produce annual feeder
portfolios (undergrounding, covered conductor, vegetation management, etc.)by
weighing critical infrastructure such as hospitals, airports, medically vulnerable
customers, so the grid hardening approach prioritizes community resilience along with
respective BCRs.
Line Rebuilding
The Company considers rebuilding lines with hardened designs as a wildfire mitigation
strategy. 2026 WMP at 19. Staff believes that some transmission and distribution ("T&D")
projects may be driven by factors other than wildfire mitigation, such as reliability, end of life
replacement, or load growth. Staff recommends the Commission direct the Company to include
a list of all T&D projects that includes wildfire mitigation as a driver, such as rebuild projects,
overhead and undergrounding hardening projects, in future WMP filings. For each project, the
Company should include the following: the name of the project, project type (transmission or
distribution), primary driver(wildfire, future growth, end of useful life, etc.), respective wildfire
risk zone tier, and an explanation of how the wildfire mitigation priority of the project affected
the project design, cost, and timeline.
Third-Party Undergrounding Study
The Company hired a third-party vendor, Exponent, Inc. ("Exponent"), to conduct a
study regarding overhead to underground conversion of a selected portion of its distribution
STAFF COMMENTS 12 APRIL 16, 2026

lines. The analysis spans approximately 177 feeders (over 2,000 overhead distribution line
miles) located in Washington and Idaho. 2026 WMP Appendix C at 43. The study provides a
quantitative, monetized CBA of undergrounding overhead distribution feeders to reduce utility
caused ignition risk, improve reliability with feeder-specific BCRs to identify feeders where
undergrounding is economically justified.
Staff believes the overall analytical and engineering modeling framework, data inputs,
and benefit categories (e.g., reliability, vegetation management, etc.) included in the CBA study
are generally reasonable. However, Staff identified the following limitations to the study.
I. The fundamental premise of relying on outage history to justify conductor
undergrounding as a wildfire mitigation measure is not sufficiently supported. The
CBA study relies primarily on the Company's historic outages data(from January
2018 to June 2024), where the Company's own analysis discovered that there is no
statistically significant correlation between historic outage data and historic utility-
caused ignitions. See Company's Response to Staff Production Request No. 8. Staff
identified this same limitation in its assessment of the Company's risk modeling
approach, as noted in the "Gaps in the Company's Approach and Improvements to
Consider" section.
2. The use of a fixed 19%Expected Annual Loss ("EAL") attribution for utility-caused
wildfire losses is overly generalized. The Company does not have any utility-specific
data related to wildfire losses that can be translated into dollars, so Exponent's study
used EAL, defined by Federal Emergency Management Agency's ("FEMA"), as a
parameter of wildfire losses. 2026 WMP Appendix C at 26-30. FEMA's EAL
estimation(measured in US dollars) is based on a combination of exposure, annual
frequency, and historical losses for 18 different natural hazards.9 As FEMA's EAL
includes losses associated with both utility and non-utility-caused wildfires, Exponent
used a fixed 19%EAL from the California State Auditor Report No. 2021-117,
following the State of California's fire damages during the five year period from 2016
through 2020.10 2026 WMP Appendix Cat 28.
9 https://www.fema.gov/sites/default/files/documents/fema_national-risk-index_methodolog_y-hazards-overview.pdf;
Accessed: 04/06/2026.
10 hlWs:Hinformation.auditor.ca. og v/reports/2021-117/index.html;Accessed: 04/06/2026.
STAFF COMMENTS 13 APRIL 16, 2026

3. The study's CBA calculations are not based on asset-specific ignition probabilities.
Applying a fixed share of EAL to utilities could over or underestimate the losses
across the Company's wildfire risk zones, and it might not accurately reflect the
actual cost-benefits for those pilot undergrounding project's feeders.
4. The outcome of the study is dependent on the Company's existing wildfire risk
modeling results as outlined in the 2026 WMP. As the Company moves forward with
a revised wildfire risk modeling approach,undergrounding recommendations based
on the existing study's CBA may not properly align with the revised modeling risk
zones in the Company's future WMP filings.
5. The undergrounding study does not provide comparative CBAs of undergrounding
compared to other alternatives (such as covered conductor, overhead upgrades, etc.).
Covered Conductor Pilot Study
The Company conducted a covered conductor study on a 2.5-mile section of a
distribution feeder near Springdale, Washington. 2026 WMP at 23. Being a pilot project, the
current WMP does not provide any performance metrics, such as contact-fault reductions, outage
minutes avoided,partial-discharge/thermal anomalies, connector failure rates, etc., nor does it
demonstrate a quantified roadmap (e.g., miles per year, feeder selection criteria, material
standards, and target risk reduction) regarding future implementation of such projects. As a
result, Staff was unable to effectively benchmark the Company's progress against other major
utilities who publish covered-conductor mileage and annual targets.11,12 Accordingly, the
Company should consider providing short-term(3 to 5 year) measurable targets, and the projects
selection criteria based on reasonableness of costs as a part of its future WMP filings.
VII. Situational Awareness and Monitoring
Idaho Code § 61-1803(3)(f) and the Guidelines require each WMP to discuss how the
Company monitors weather conditions and wildfire risk. In 2026, the Company forecasts $4.4
million in capital expenditures and$175,000 in O&M for Idaho's Situational Awareness
"h Vs://www.sce.com/outages-safety/wildfire-safety/wildfire-mitigation-efforts;Accessed: 04/07/2026.
'Z h!Ws://www.hawaiianelectric.com/safety-and-outages/wildfire-safety;Accessed: 04/07/2026.
STAFF COMMENTS 14 APRIL 16, 2026

program. Company's Response to Staff Production Request No. 33 Attachment A. Over the
five-year plan, the Company forecasts spending a total of$13.2 million in capital expenditures
and$1.2 million in O&M for Idaho situational awareness. Id. Through its review, Staff believes
the Company has substantially met the situational awareness and monitoring requirements of
Idaho Code § 61-1803(f) and the Guidelines. However, Staff discusses below its
recommendations regarding the level of detail to include for weather stations and wildfire
detection cameras in the Company's future WMP filings.
Fire Risk Index
The Company performs dynamic risk assessments on its Fire Weather Dashboard, which
refreshes every 2 hours and generates a FRI to provide system-wide alerts and to assist local
operators in making informed decisions around fire and reliability risks. According to the
Company's 2026 WMP, approximately 36% of its system-wide distribution system lies in
elevated WUI risk areas where approximately 13% of Idaho's distribution lines fall within the
elevated WUIs. 2026 WMP at 9.
Weather Stations
The Guidelines require the Company to identify the systems, tools, or external resources
used to monitor weather, fire potential, or other situational awareness indicators. Guidelines at 6.
The Company stated that it uses its WUI risk map and its Fire Weather Dashboard and plans to
launch a new Fire Risk Model in 2026, to aid in its daily situational awareness. 2026 WMP at
11. The Company uses data from its own weather stations and other publicly available data in its
Fire Weather Dashboard.
While the Company briefly states that it integrates information from National Weather
Service forecasts in its Fire Weather Dashboard, it did not explain how it utilizes other weather
station data sources. In its response to Staff Production Request No. 5, the Company explained it
utilized data accessed from Synoptic and MesoWest. Staff believes these details should be
documented within the WMP for transparency and completeness; therefore, Staff recommends
the Commission direct the Company to add a description of the publicly available data the
Company uses as part of its situational awareness efforts.
STAFF COMMENTS 15 APRIL 16, 2026

Wildfire Detection Cameras
The Company has installed 15 wildfire detection cameras as of 2025, with five located in
Idaho. 2026 WMP at 13. The Company has worked with IDL and the Washington Department
of Natural Resources in the placement of cameras. 2026 WMP at 14. The camera network has
been viewed over 54,000 times. Id. The Company has a target to add 26 cameras in Idaho by
2030 with ten installations anticipated in 2026. Company's Response to Staff Production
Request No. 33 Attachment A.
As the Company plans to expand its camera network, Staff suggests the Company include
the same level of detail provided in its response to Staff Production Request No. 4 in future
WMP filings. The additional details include: locations of focus, average cost of installation,
timeframe for installation of cameras, cost-benefit analysis, and other alternatives considered.
Additionally, Staff suggests the Company consider including metrics that track the number of
ignitions detected, response time to ignitions, whether the Company responded, and whether its
infrastructure was involved.
VIII. Infrastructure Inspection and Maintenance
Idaho Code § 61-1803(b),Idaho Code § 61-1803(g)(i), and the Guidelines require
discussion of the frequency and standards for inspections of each type of electric infrastructure
within areas of elevated wildfire risk and targets or goals to be achieved within the WMP. Clear
inspection guidelines support timely inspections, maintenance, and emergency repairs, reducing
reliability and safety risks during high fire danger conditions and in heightened wildfire risk
zones. Based on its review of the WMP, Staff believes the Company has substantially met the
applicable WSCA and Guidelines requirements. However, Staff has identified areas for
improvement in the Company's future WMP filings.
Inspection Details
The Company describes inspections of wood poles, distribution lines, and transmission
lines and provides a summary of distribution and transmission related outages. 2026 WMP at
23-26. However, the WMP does not provide a detailed explanation of what was inspected,
which may be documented in a checklist or manual. Staff recommends the Commission direct
STAFF COMMENTS 16 APRIL 16, 2026

the Company to include the details of all inspections, including what is inspected, in future WMP
filings.
Deficiency Backlog Monitoring
The Company should identify deficiencies through its inspections and other related
activities. Monitoring and correcting inspection deficiencies according to their respective
priority is essential to protect safety and system reliability because a growing backlog signals
that additional resources or process changes are needed to keep risks from escalating. The
Company provided this data in response to Staff Production Request No. 48. Staff believes the
Company should include the data below for the three previous years in future WMP filings for
deficiencies related to infrastructure in heightened fire risk areas:
1. Number of deficiencies found by category type (P1, P2, etc.);
2. Number or percentage of deficiencies repaired by priority type;
3. Goal for remediation to be complete by category;
4. Average time to repair by category type; and
5. Pending repairs at year-end by category type.
Quality Assurance
Similarly, a Quality Assurance ("QA")program is essential because it verifies that
completed corrective work truly resolves the identified issue, ensuring safety, reliability, and
accountability in the utility's maintenance practices. Staff believes the Company should describe
the QA process for each inspection program in future WMP filings. This should include what is
selected for a QA audit(i.e., 100% in high fire risk areas, or 20% sample of all-service-area
work), frequency of the audits (i.e., weekly, monthly), and process for addressing any items that
failed to meet the Company's standards.
IX. De-Energization and Line Operation Practices
Idaho Code § 61-1803(b),Idaho Code § 61-1803(g)(ii), and the Guidelines require each
WMP to include descriptions of de-energization protocols and line operation practices.
Additionally, the WMP includes discussion of operational changes during heightened wildfire
risk days or in high wildfire risk zones which includes line settings, restrictions to workforce
STAFF COMMENTS 17 APRIL 16, 2026

practices, and changes to operational procedures. Operational changes during heightened
wildfire risk days reduce the likelihood of ignition not only from electrical infrastructure but also
from activities performed on that infrastructure, such as routine maintenance or emergency
repairs.
The Company describes its operations and emergency response in its 2026 WMP on
pages 41 through 45. Staff believes the Company has adequately described its de-energization
protocols and associated operational practices. However, Staff has identified areas for
improvement in the Company's future WMP filings.
Operation Practices
The Company provides a description of how recloser settings are changed based on
different Fires Safety Mode levels. 2026 WMP at 44. However, the Company does not provide
similar summaries for its workforce practices and requirements. Staff suggests the Company
consider providing similar summary tables or narratives in future WMP filings that describe how
workforce practices and requirements change due to an increased Fire Risk Index and/or Fire
Safety Mode, similar to how the Company summarized recloser setting changes with Fire Safety
Mode on page 44. This should include descriptions of content of tail board meetings,
required equipment for crews and vehicles, required activities such as dedicated fire watches,
and restricted or prohibited work hours.
Public Safety Power Shutoff
Idaho Code § 61-1803(g)(ii) and the Guidelines specifically require the Company to
describe its standards, criteria, and operational protocols for de-energization, including PSPS.
Staff believes the Company's PSPS process, as described throughout the 2026 WMP, is
reasonable and generally consistent with industry practices.
The Company executed its first PSPS event in 2024, providing experience that can
inform future PSPS execution. The Company should continue refining its PSPS protocols based
on planned and executed events. Ongoing evaluation and improvement of PSPS procedures will
be important to ensure that public safety objectives are met while minimizing customer
disruption. Specifically, 2026 WMP states how the Company may stand up a Community
Resource Center("CRC"). The Company should consider including documentation in its future
STAFF COMMENTS 18 APRIL 16, 2026

WMP filings describing when and how a CRC is setup during PSPS events. Additionally, the
Company should consider including additional details about resources available to call center
agents within WMPs, as detailed in the Company's response to Staff Production Request No. 24.
X. Vegetation Management
Idaho Code § 61-1803(3)(g)(iii) and the Guidelines require each WMP to include a
discussion of vegetation management and enhanced vegetation management for heightened fire
risk areas. Staff reviewed the Company's routine and enhanced vegetation management
practices described in the 2026 WMP. The Company estimates an average of$11.58 million in
annual O&M expenses for these programs. 2026 WMP Appendix B at 2 and Company's
Response to Staff Production Request No. 40. Staff believes the Company's routine and
enhanced vegetation management programs are critical components of wildfire mitigation and
that the Company has substantially met the WSCA and Guidelines requirements. However, Staff
has identified areas of potential improvement in the Company's future WMP filings.
Quality Assurance
As stated above regarding an inspection QA program, Staff believes a QA program is
essential, as it verifies that corrective work truly resolves the identified issue, ensuring safety,
reliability, and accountability. The Company described its vegetation management QA process
in its response to Staff Production Request No. 30; however, it was not included within its WMP.
The Company should consider including a description of its vegetation management QA process
in or as an attachment to future WMP filings.
Wildfire Risk Specific Training and Certification
The Company's vegetation management is done according to federal and industry
standards that include ANSI A300,National Electrical Safety Code Section 21, Part 2, Rule 218,
and North American Electric Reliability Corporation("NERC") Standards FAC-003-5 and FAC-
501-WECC-4. Each standard addresses clearance, tree/shrub conditions, how to safely and
appropriately prune or remove vegetation, and maintain vegetation health.
IDL's comments mention the standards do not address ignition potential or fire
propagation perspectives of vegetation management such as "ladder" fuels, which allow
STAFF COMMENTS 19 APRIL 16, 2026

wildfires to progress from the ground to the canopy. IDL recommended the Company consider
adding standards specific to wildland fire to training and certification required for personnel
doing vegetation management work. Staff agrees with IDL that the Company should consider
adding standards specific to wildland fire, such as the International Society of Arboriculture's
Wildfire Risk Reduction Qualification, to the qualification standards for personnel performing
vegetation management.
Vegetation Induced Fault, Outage and Ignition Data
The Company's WMP describes system level transmission and distribution fault, outage,
and ignition data over the last 3 plus years in its 2026 WMP on pages 25, 27, 36 and in Appendix
E on pages 13 and 17. Appendix E was included in the 2026 WMP in compliance with Order
No. 52980. Staff recommends that the Commission direct the Company to provide similar
summary data in future WMP filings. In addition, the Company should consider providing this
data at the line and feeder level, if that level of granularity is possible, with the existing data the
Company currently captures.
XI. Other WMP Recommendations
Filing Date
The Company requested to file its annual WMP filing on or about November 1 of each
year. Staff recommends that the Commission direct the Company to file its annual WMP on or
about November 1 of each year.
Cost-Benefit Approach
Idaho Code § 61-1804(b) requires the Commission to consider the feasibility of the plan
and the cost of its implementation. In Order Nos. 36774 and 36882, the Commission directed
the Company to include a cost-benefit analysis within its WMPs and provided guidance on the
information necessary to support its analysis.
The Company stated that it is developing a comprehensive wildfire risk modeling
decision support tool. 2026 WMP at 12. The tool is intended to assist in evaluating risk at the
asset level and to inform cost-benefit analyses for mitigation strategies. Id. The Company
indicates the tool will provide two key analyses: (1) a benefit calculation(averted wildfire risk
STAFF COMMENTS 20 APRIL 16, 2026

costs as baseline risk less post-mitigation risk) and(2) a cost-benefit ratio comparing the
monetized benefit to mitigation costs. See Company's Response to Staff Production Request No.
35. The tool remains under development and is expected to begin producing results in 2026.
2026 WMP at 12.
While benefits may not always be quantified solely in monetary terms, Staff believes the
Company should apply a consistent, transparent, and repeatable methodology across projects.
Such consistency is necessary to evaluate whether projects are prioritized using comparable
criteria. Additionally, when qualitative benefits are applied, the Company should define what
they are and the efficacy of mitigating wildfire risk.
The Company should include a clear description of the wildfire risk modeling tool in
future WMP filings, including key factors and assumptions. The Company should also consider
identifying conditions when it deviates from the model's output, including its cost-benefit
analysis. Additionally, the Company should consider quantifying the risk reduction associated
with specific infrastructure mitigation measures.
Although Staff reviewed the forecasted capital and O&M expenditures that were
inadvertently omitted from the WMP, approval of the WMP does not guarantee approval of cost
recovery. The prudence and recovery of WMP-related capital expenditures and O&M expenses
will be evaluated in a future rate proceeding.
Grants
The 2026 WMP did not mention grants that the Company was awarded or applied for. In
its response to Staff Production Request No. 32, the Company provided some information of
three grants the Company applied for as part of its wildfire mitigation efforts, none of which the
Company was awarded as of January 2026. Id.
Staff believes this information is necessary to be part of a WMP,because grant funding
may mitigate potential increased wildfire mitigation costs to ratepayers. Additionally, because
the Commission must consider the cost implementation of WMP expenditures, this information
could aid in the Commission's review of the cost and feasibility of the Company's planned
actions. Staff recommends the Commission direct the Company to provide details of all funding
alternatives and sources pursued within future WMPs.
STAFF COMMENTS 21 APRIL 16, 2026

Metrics
The 2026 WMP does not describe the metrics the Company will use for its wildfire
mitigation efforts, operations, and projects. In response to Staff Production Request No. 1, the
Company provided a list of specific metrics that will be used to evaluate the effectiveness of the
WMP programs.
Staff believes these metrics and the associated data are valuable and should be
incorporated into the WMP to track progress, demonstrate the plan's feasibility, and evaluate the
extent to which it reduces wildfire. Therefore, Staff recommends the Commission direct the
Company include all metrics used for the WMP within each respective sections of future WMP
filings and provide the data in a format that can easily be tracked across WMP filings.
Specifically for the inspections and vegetation management programs, there are industry-
standard metrics that may be beneficial to track reliability as the Company implements its WMP.
These include the System Average Interruption Duration Index ("SAIDI"),13 System Average
Interruption Frequency Index("SAIFI"),14 Customer Average Interruption Duration Index
("CAIDI"),15 and Momentary Average Interruption Frequency Index("MAIFI"). 16 These
metrics allow utilities to benchmark reliability performance over time, identify poor-performing
circuits to prioritize investment, and assess the effectiveness of vegetation management,
protection schemes and system maintenance and hardening. Accordingly, Staff believes the
Company should consider tracking and reporting the last three years of these metrics at the
system and circuit levels in future WMP filings.
Idaho Requirements Crosswalk
The Guidelines require the Company to provide a section in its WMP that describes how
the Company addressed each of the Commission's orders and Staff s recommendations.
Guidelines at 8. In Appendix A, the Company provided a crosswalk of the WMP and the
WSCA, however it did not include all of the Commission ordered requirements. In future WMP
filings, Staff suggests the Company include all the Commission ordered components in its
" SAIDI represents the total number of minutes of interruption the average customer experiences.
14 SAIFI represents the average number of times a customer experiences an outage during the year.
15 CAIDI is the average number of minutes it takes to restore non-momentary electric interruptions.
16 MAIFI is the average number of momentary interruptions that a customer would experience during a given period
(typically a year).
STAFF COMMENTS 22 APRIL 16, 2026

Appendix A, including the following: the Order No. 36774 (especially the Guidelines), Order
No. 36929, and any other Commission-ordered requirements. This would help track all the
required components of WMPs and explain how the Company addresses each.
XIL Coordination with IDL
Idaho Code § 61-1804(3)requires the Commission to consult with the State Forester at
IDL, specifically regarding vegetation management, reduction of wildfire fuels, and other duties
of the state forester under Title 38, Idaho Code.
On December 19, 2025, IDL submitted a letter stating it would not intervene in this case,
unless IDL found it necessary.
On January 26, 2026, Staff met with the Company and IDL to discuss the Company's
WMP, specifically to discuss the Company's wildfire risk model and vegetation management.
On January 29, 2026, Staff met with IDL to discuss IDL's desired participation in the
case. Staff and IDL agreed to include IDL on meetings with the Company.
On February 13, 2026, Staff met with the Company and IDL to clarify the Company's
responses to production requests.
On March 13, 2026, IDL filed its comments and recommendations to the Company. IDL
expressed concerns with (1) the Company's risk model descriptions within the WMP, (2) the
cost-benefit analysis approach, (3)the need to clarify the Company's actions for internal and
external wildfire events, (4)the need for the Company's fair market value approach to be
defined, (5) the Company's vegetation management not addressing wildland fire related issues,
and(6) the Company's integration with county fire planning groups. IDL comments at 2-3. Staff
believes the recommendations laid out within IDL's comments are reasonable and support the
recommendations.
Public Comments
As of April 14, 2026, two public comments were filed, both of which were filed by IDL.
On December 19, 2025, IDL commented it had received notice of the Company's WMP and
noted it would not formally intervene. On March 13, 2026, IDL provided several
recommendations for the Company's future WMP filings, as described above.
STAFF COMMENTS 23 APRIL 16, 2026

STAFF RECOMMENDATION
Staff recommends the Commission issue an order that:
1. Approves the Company's 2026 Wildfire Mitigation Plan; and
2. Allows the Company to file future annual Wildfire Mitigation Plans on or about
November 1"of each year.
For future WMP filings, Staff recommends the Commission direct the Company to:
1. Add a line item in its cost forecasts for internal wildfire mitigation labor;
2. Provide copies of all wildfire related training in or as attachments and provide a table
identifying the role, number of people, training date (i.e., date, month, or quarter), and
type of training completed;
3. Add a detailed description of the risk modeling methodology and determination of
geographical risk areas;
4. Include a list of all T&D projects that includes wildfire mitigation as a driver within
WMPs, such as rebuild projects and grid hardening projects, that includes the following:
project name,project type (transmission or distribution),primary driver(wildfire, future
growth, end of useful life, etc.), respective wildfire risk zone tier, an explanation of how
the wildfire mitigation priority of the project affected the project design, cost, and
timeline;
5. Add a description on the publicly available data the Company uses as part of its
situational awareness efforts;
6. Include the details of all inspections the Company conducts, including what is inspected;
7. Continue providing similar summary data of the Company's transmission and distribution
fault, outage, and ignition data within WMPs;
8. Provide details of all funding alternatives and sources pursued within the WMP; and
9. Include all metrics used for the WMP within each respective sections and provide the
data in a format that can easily be tracked across WMP filings.
STAFF COMMENTS 24 APRIL 16, 2026

Respectfully submitted this 16th day of April 2026.
ZV
Jeffrey R. Loll
Deputy Attorney General
Technical Staff. Kimberly Loskot, Karla Ducharme, Shubhra Deb Paul, and Ray McArthur
I:\Utility\UMISC\COMMENTS\AVU-E-25-15 Comments.docx
STAFF COMMENTS 25 APRIL 16, 2026

CERTIFICATE OF SERVICE
I HEREBY CERTIFY THAT I HAVE THIS 161h DAY OF APRIL 2026, SERVED
THE FOREGOING COMMENTS OF THE COMMISSION STAFF , IN CASE NO.
AVU-E-25-15, BY E-MAILING A COPY THEREOF TO THE FOLLOWING:
ANNI GLOGOVAC ELIZABETH ANDREWS
COUNSEL FOR REGULATORY SR. MGR., REVENUE REQUIREMENTS
AFFAIRS AVISTA CORPORATION
AVISTA CORPORATION PO BOX 3727
PO BOX 3727 SPOKANE WA 99220-3727
SPOKANE WA 99220-3727 E-mail: liz.andrews&avistacorp.com
E-mail: anni.glo og vac(cavistacorp.com
avistadocketskavistacorp.com
Potlatch Deltic Forest Holdings, LLC:
PETER J. RICHARDSON
RICHARDSON ADAMS, PLLC
515 N. 271h STREET
BOISE, ID 83702
E-mail: petergrichardsonadams.com
MICHELE TYLER, ESQ.
WADE SEMELISS
BRIAN SCHLECT, ESQ.
ANNA TORMA
PotlatchDeltic Forest Holdings, LLC
601 W. FIRST AVE, SUITE 1600
SPOKANE, WA 99201
E-mail:
michele. . ler(4potlatchdeltic.com
wade.semeli ss(&,potlatchdeltic.com
brian.schlect&potlatchdeltic.com
anna.torma(&,potlatchdeltic.com
PATRICIA JORDA , SECRETARY
CERTIFICATE OF SERVICE