Trump's Power Play: Can He Overrule California's Pollution Rules?

California has long been known for its severe air pollution and climate change issues, with state officials implementing rules to regulate diesel vehicles and reduce air pollution and greenhouse gases. However, with the election of Donald Trump as President, there is concern that these environmental efforts may be undone. Trump has taken executive actions and issued orders to override California's environmental policies, including those related to water management and air pollution. These actions have potential implications for the state's ability to combat climate change and protect its residents' health and safety. The question now arises: Can Trump legally revoke California's tougher pollution rules?

Trump's executive orders to revoke California's pollution rules

In 2025, Donald Trump issued several executive orders that directly impacted California's pollution rules and environmental policies. These orders came after Trump's visit to Los Angeles, which had been devastated by wildfires, and amid concerns about the state's water management practices.

One of the most notable executive orders was Trump's directive to override California's water management practices if they were found to be ineffective. This order was issued in response to the wildfires that had killed at least 28 people and burned more than 35,000 acres. Trump falsely claimed that the state's water shortages during the wildfires were due to California's water management policies and that the Democratic governor, Gavin Newsom, had refused to provide water from the northern part of the state to fight the fires. The order directed federal agencies to "take actions to override existing activities that unduly burden efforts to maximize water deliveries" and instructed the US Bureau of Reclamation to deliver more water and hydropower through the Central Valley Project, even if it conflicted with state or local laws.

Another executive order targeted California's clean vehicle policies, including the "EV mandate." Trump ordered the end of the "Green New Deal" and directed agencies to pause any disbursement of funds for the National Electric Vehicle Infrastructure (NEVI) and the Charging and Fueling Infrastructure (CFI) programs. The order also eliminated "state emissions waivers that function to limit sales of gasoline-powered automobiles," directly impacting California's waivers under the Clean Air Act to set emissions controls within its borders.

California had previously withdrawn its requests for waivers and authorizations from the US Environmental Protection Agency (EPA) for its clean-air rules, including regulations phasing out diesel trucks and requiring cleaner locomotives, as the Trump administration was unlikely to approve them. This withdrawal was a significant setback for the state's efforts to combat air pollution and climate change.

Trump's executive orders faced criticism from environmental groups, who argued that they put communities at risk and hindered progress in addressing air quality and climate change. The orders also raised concerns among California water management officials, advocates, and elected officials, who questioned the impact on water availability and the potential for flooding and destruction of local communities.

California's diesel truck ban

In January 2025, California withdrew its clean-air rule phasing out diesel trucks. The state's Air Resources Board Chair, Liane Randolph, stated that the withdrawal was due to the uncertainty presented by the incoming Trump administration, which had previously attacked California's programs to protect public health and the climate.

The withdrawal of the diesel truck ban was a setback for reducing California's air pollution but a win for trucking companies. The ban was part of California's Advanced Clean Fleet rule, which aimed to reduce air pollution and greenhouse gases by phasing out diesel trucks and requiring large trucking companies to convert their medium and heavy-duty fleets to electric or hydrogen models by 2042. The rule would have had a significant impact on the state's environment and economy, ending diesel's stronghold on goods movement in California.

The withdrawal came after the Biden administration approved the California Air Resources Board's mandate phasing out new gas-powered cars by 2035 but failed to approve waivers for four diesel vehicle standards that the state had adopted. The Trump administration had previously taken aim at California's special status to enact stricter emission rules, and it was unlikely that the new administration would allow California to implement the diesel truck ban.

Environmentalists criticized the withdrawal, arguing that diesel exhaust is one of the most dangerous kinds of air pollution and that the ban was necessary to protect the health of communities in California, especially low-income and disadvantaged communities of color near ports, freeways, and warehouses.

California's Air Resources Board is now assessing its options to continue its progress in improving the state's air quality and reducing harmful pollutants, but it may have to suspend any future rule-making for vehicles during the Trump administration.

Trump's impact on California's water supply

In the aftermath of the deadly wildfires in California in January 2025, President Donald Trump issued an executive order to increase water supply in the state. The order directed federal agencies to overrule California's regulations on endangered species, such as the Endangered Species Act (ESA), which seeks to protect certain fish species by minimising water infrastructure. Trump claimed that these environmental policies were “actively harmful” and restricted water availability, hindering efforts to fight the wildfires.

Trump's order specifically targeted rules that guide two massive Delta water systems: the federal Central Valley Project and the state-operated State Water Project. These systems provide water to millions of acres of farmland and 30 million people, drawing water from rivers that flow into the Sacramento-San Joaquin Delta and San Francisco Bay. The order instructed the Secretary of the Interior and the Secretary of Commerce to "immediately take actions to override existing activities that unduly burden efforts to maximise water deliveries".

In response to Trump's directive, the U.S. Army Corps of Engineers released water from two reservoirs in the foothills of the southern Sierra Nevada: Lake Kaweah and Lake Success. This release was intended to increase water flow to Southern California. However, critics questioned the timing and effectiveness of this move, as the reservoirs typically irrigate fields later in the year, and the released water would not reach Los Angeles. Experts and officials, including Senator Alex Padilla and Senator Adam Schiff, expressed concerns that the unscheduled releases endangered residents downstream and would not address the water needs of Los Angeles.

Trump's actions reflect a misunderstanding of California's complex water supply system. The president claimed that California could simply "open the valve" to let more water flow southward, despite the state's water management officials, advocates, and elected officials disputing this notion. Trump's order also overlooked the fact that Los Angeles' water supply comes mostly from sources other than the Delta or the Central Valley, and that Southern California cities have ample water reserves following two wet winters.

In conclusion, Trump's impact on California's water supply has been controversial. While he aimed to increase water availability in the aftermath of the wildfires, his actions have been criticised for disregarding environmental protections, endangering communities, and failing to address the actual water needs of the affected regions.

California's air pollution waiver

California has been granted waivers by the U.S. EPA to set its own vehicle emissions standards under the Clean Air Act. This is due to the state's unique air pollution problems, including severe smog and climate change impacts such as rising temperatures, increasing levels of ozone, and exacerbated wildfires. The waivers allow California to implement regulations that are stricter than federal standards, such as the Advanced Clean Cars rule, which aims for 100% sales of zero-emission vehicles by 2035.

The state's authority to set its own emissions standards is based on the Clean Air Act, which was affirmed by Congress due to the success of California's standards in protecting public health and driving innovation. The Act does not include a process for revoking waivers, and no waiver has ever been revoked. Waivers do not expire but can be superseded by new waivers with more stringent standards.

California's vehicle emissions rules have resulted in major technological advances, such as the development of the catalytic converter and onboard diagnostics. The state has applied for and received more than 100 waivers over the past 50 years, and these waivers have driven emission control technologies that have benefited all Americans.

However, there have been challenges to California's authority to set its own emissions standards. During the Trump administration, there were attempts to revoke the state's waivers, arguing that a federal fuel economy statute (EPCA) blocked California's program. These attempts were ultimately unsuccessful, and the Biden administration reversed these efforts in 2022.

In summary, California's air pollution waiver is a crucial tool for fighting air pollution in the state and has driven major advances in vehicle pollution technology nationwide. The state's authority to set its own standards is protected by the Clean Air Act and has a long history of precedent, making it difficult for any administration to legally revoke the waivers.

Trump's stance on clean vehicle policies

Trump has promised to eliminate what he calls "the electric vehicle mandate" imposed under former President Joe Biden. However, there is no actual mandate to force the purchase of EVs; instead, Biden's policies encouraged Americans to buy them and car companies to shift from gas-powered vehicles to electric cars. Trump's order, entitled "Unleashing American Energy," seeks to remove regulatory barriers to motor vehicle access and ensure a level regulatory playing field for consumer choice in vehicles.

Trump's actions could severely curtail the availability of federal incentives for electric vehicles and lead to the dismantling of standards that are driving the clean vehicle transition and saving drivers money. Repealing EPA standards and federal incentives may cost car buyers more in lifetime fuel and maintenance costs, increase greenhouse gas emissions, and result in higher healthcare costs. It could also put investments and jobs in the electric vehicle industry in jeopardy, as manufacturers have announced nearly $200 billion in investments in U.S. electric and battery manufacturing in the last two years.

Trump has also taken aim at California's special status to enact stricter vehicle emission rules, which was granted by the federal EPA under the Clean Air Act. During his first term, Trump's administration targeted California's ability to set its own aggressive emission standards, but the Biden administration reversed these efforts in 2022. With Trump back in office, California has withdrawn its requests for EPA approval of its clean-air rules as it is unlikely that the Trump administration will allow them. This includes rules regulating diesel vehicles and phasing out the sale of new gas-powered cars by 2035, which are essential to addressing California's severe air pollution and combating climate change.

Frequently asked questions