HomeMy WebLinkAboutCity of San Luis Obispo - Letter on Endangerment Finding RulemakingCity of San Luis Obispo, Office of the City Council, 990 Palm Street, San Luis Obispo, CA, 93401-3249, 805.781.7114,
slocity.org
September 19, 2025
U.S. Environmental Protection Agency
1200 Pennsylvania Avenue, NW
Washington, DC 20460
VIA ELECTRONIC SUBMISSION
Subject: Proposed Rule, Reconsideration of 2009 Endangerment Finding and Greenhouse
Gas Vehicle Standards,” 90 Fed. Reg. 36,288 (Aug. 1, 2025)
Docket No.: EPA–HQ–OAR–2025–0194; FRL–12715–01–OAR
To Whom It May Concern:
The City of San Luis Obispo respectfully submits this comment letter to register firm
opposition to the U.S. Environmental Protection Agency’s proposal to reconsider or rescind
the Endangerment Finding for greenhouse gases (GHGs) and to eliminate federal GHG
emission standards for motor vehicles. As a municipal government with a responsibility to
safeguard public health, safety, and welfare, the City urges EPA to uphold both the
Endangerment Finding and the vehicle GHG standards, which remain essential tools in
mitigating the adverse impacts of climate change on our community.
1. Local governments are where climate disasters happen; we are the ones who
experience, respond to, and recover from disasters that are empirically proven to
have been exacerbated by greenhouse gas emissions.
Municipalities such as the City of San Luis Obispo are already confronting the measurable
impacts of climate change, driven in substantial part by greenhouse gas (GHG) emissions
from motor vehicles and power generation facilities in the United States. Increasing average
temperatures, intensifying precipitation events, and the growing frequency of extreme
weather are placing significant burdens on public infrastructure and generating escalating
fiscal impacts for local governments. The City has experienced recent disasters including
historic drought, heat, flooding, and fire. The most recent examples include:
• Regional Wildfires: In 2025, regional wildfires, including the Madre Fire and the
Gifford Fire—burned more than 210,000 acres. Their rapid expansion was driven by
record high temperatures, low humidity, and strong winds, conditions that are
becoming increasingly common as a result of climate change. The City experienced
smoke impacts, and local taxpayers contributed to response costs through the
deployment of municipal personnel to provide mutual aid. Beyond the direct physical
threats, these events also exacerbate the emerging insurance crisis, with rising costs
and declining availability posing serious risks to housing affordability and stability in
our community.
• Localized Flooding Atmospheric River Flooding (2021–2023): A series of record-
breaking storms produced rainfall exceeding twice the seasonal average, resulting in
extensive flooding, damage to critical infrastructure, and major transportation
disruptions. These extreme precipitation events align with established climate
projections. The storms caused significant losses to private property and public
assets, including roadways and bridges, and imposed ongoing fiscal impacts on the
City’s municipal budget.
The ability for private entities to release pollution that results in these direct impacts to our
community is fundamentally unfair and substantially impacts our collective wellbeing. Rolling
back the Endangerment Finding and vehicle GHG standards would undermine our ability to
protect residents from these escalating harms.
2. The Endangerment Finding is based on sound, extensive, and conclusive science,
including federal and state climate assessments.
EPA’s 2009 Endangerment Finding was based on a substantial body of peer-reviewed
science, which has only strengthened over the past decade. The Fifth National Climate
Assessment (2023) concludes that climate change is already affecting U.S. communities,
with cities facing heightened risks from extreme heat, flooding, sea level rise, drought, and
wildfire.1 It further finds that infrastructure designed for historic climate conditions is
increasingly vulnerable, generating rising costs for municipalities and residents.2
These conclusions, supported by thousands of peer-reviewed studies and reinforced by
statewide analyses such as California’s Fourth Climate Change Assessment, are directly
reflected in the City of San Luis Obispo’s recent experiences with climate-related impacts.
The City therefore urges EPA to act on the best available science in maintaining and
strengthening regulation of greenhouse gas emissions, particularly in light of the growing
risks to local infrastructure and community resilience.
3. Rescinding vehicle GHG standards would eliminate any meaningful regulation of
transportation emissions.
Transportation is the largest source of greenhouse gas (GHG) emissions in the United States,
responsible for 28 percent of total emissions in 2022 according to EPA data.3 Within the City
of San Luis Obispo, transportation accounts for more than half of communitywide emissions.
Although transportation is the dominant emissions sector, Section 209 of the Clean Air Act
preempts states and municipalities from establishing independent motor vehicle GHG
standards.4 If EPA rescinds the Endangerment Finding and eliminates federal vehicle GHG
standards, the City of San Luis Obispo will be left with minimal capacity to address this
primary source of emissions, despite incurring the associated public health, infrastructure,
1 NCA5, Cities and the Built Environment, Key Message 1, p. 1842.
2 NCA5, Cities, p. 1845.
3 U.S. EPA, Inventory of U.S. Greenhouse Gas Emissions and Sinks (July 1, 2025),
https://www.epa.gov/ghgemissions/inventory-us-greenhouse-gas-emissions-and-sinks.
4 42 U.S.C. § 7543.
and fiscal costs. Rather than expanding local authority, repeal would remove one of the only
effective mechanisms available to reduce transportation-related GHG emissions.
Summary
The City of San Luis Obispo requests that EPA withdraw the current proposal and maintain
both the Endangerment Finding and the federal motor vehicle GHG standards. Continued
recognition of the risks posed by GHG emissions, and the preservation of effective federal
standards, are essential to protecting public health and welfare, safeguarding local fiscal
stability, and ensuring the capacity of municipalities to deliver core services in the face of
climate impacts.
Respectfully submitted,
Erica A. Stewart
Mayor
City of San Luis Obispo