More than a dozen states are moving to strengthen environmental protections to combat a range of issues from climate change to water pollution, opening a widening rift between stringent state policies and the Trump administration’s deregulatory agenda.

In recent months, Hawaii, New York and California have moved to ban a widely used agricultural pesticide linked to neurological problems in children, even as the administration has resisted such restrictions. Michigan and New Jersey are pushing to restrict a ubiquitous class of chemical compounds that have turned up in drinking water, saying they can no longer wait for the Environmental Protection Agency to take action.

Colorado and New Mexico have adopted new policies targeting greenhouse gas emissions from fossil fuel drilling and limiting where these operations can take place. And more than a dozen states have adopted policies that would force automakers to produce more fuel-efficient cars than required by federal standards.

The growing patchwork of regulations is creating uncertainty for American businesses as state lawmakers vie to change rules that, in past administrations, were more likely to be set at the federal level.

“At the end of the day, I think regulated entities want to know what the expectations are,” said Wendy Heiger-Bernays, an environmental health professor at Boston University. “They’d prefer not to have two different standards — one in one state and another in another state.”

Local officials say the jumble of policies also threatens to create disparities, not only in obligations placed on businesses but also in the level of protections guarding human health in different communities.

“It is difficult to communicate to your customers that New Jersey or Minnesota or Vermont has evaluated the risk to their residents differently, and that one state places a lower value on protection of public health than another,” Brian Steglitz, the water treatment manager for Ann Arbor, Mich., said last week in testimony before a panel of the U.S. House Energy and Commerce Committee.

Since President Trump took office, his administration has scaled back numerous environmental rules enacted under President Barack Obama and declined to impose federal limits on some contaminants and pesticides. The Trump administration also has reversed course on climate change, refusing to embrace the limits on greenhouse gas emissions that the federal government previously had pledged to adopt under an international agreement.

In an interview, EPA Administrator Andrew Wheeler said the federal government regularly works hand-in-hand with the states, which often are the more appropriate forum for litigating such environmental matters. For example, he said, the Trump administration has allowed many states to shape their own strategies for meeting air quality standards, rather than imposing a federal plan.

“Overall, we try to defer to the states as much as possible,” Wheeler said — though he added that the administration would oppose state action that would “interfere with national commerce” or “create uncertainties for consumers or for businesses.”

At the Interior Department, which controls industry access to vast swaths of public lands, spokeswoman Molly Block said in an email that the administration views its more business-friendly approach as a key contributor to the nation’s vibrant economic growth under Trump.

“We will continue our work to advance President Trump’s deregulatory agenda, which has boosted the American economy,” she said.

In some states — especially those newly under Democratic control — the federal approach has created a vacuum that other officials have rushed to fill. For example, when New Mexico Gov. Michelle Lujan Grisham (D) replaced a Republican in the governor’s mansion earlier this year, one of her first acts was to sign an executive order focused on climate change. It instructs regulators to develop statewide limits on greenhouse gas emissions and a more stringent renewable energy requirement for New Mexico’s power sector.

“A lot of what you see in that executive order reflects a lack of action on the federal level,” said Sarah Cottrell Propst, secretary of the New Mexico Energy, Minerals and Natural Resources Department. “The state is feeling like we need to fill the gap.”

In Orgeon, Gov. Kate Brown (D) is expected to sign a bill this week to codify federal clean air and clean water standards that were in place before Trump took office, making them enforceable under state law even if the White House rolls them back. The Trump administration is poised to replace at least three major policies this year, and has delayed or altered many others.

States also are taking the lead on chemical and pesticide regulation, as the EPA in some cases has held off on setting exposure limits or banning some substances outright.

At least a half-dozen states have pushed forward with their own plans to limit a class of compounds known as polyfluoroalkyl and perfluoroalkyl substances, or PFAS, saying ample evidence exists to regulate them. The lab-made compounds have long been used in consumer products such as nonstick pans, water-repellent fabrics and firefighting foams.

Long-term exposure has been associated with an array of health problems, including thyroid disease, weakened immunity, infertility and certain cancers, though researchers continue to study the human health implications. Because PFAS do not break down in the environment, they have become known as “forever chemicals.”

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Catherine McCabe, an EPA veteran, is now the top environmental official in New Jersey, which has proposed one of the nation’s most stringent standards for PFAS in drinking water. The state also is trying to compel five chemical manufacturers, including 3M and Dupont, to fund tests for the chemicals and to clean up contamination.

McCabe said it would be better for the nation and for industry if the federal government set a single national limit for PFAS in drinking water. “It doesn’t serve anybody’s interest for us all to be coming up with different numbers,” she said.

Given the health threat, however, McCabe said the need for action is urgent. “I would love to wait if [federal officials] were moving quickly, but they are not,” she said. “We can’t wait any longer.”

Companies such as 3M, which faces significant regulatory and cleanup costs, also have pressed for a national standard. “We support regulation rooted in the best-available science and believe that this plan may help prevent a patchwork of state standards that could increase confusion and uncertainty for communities,” the company said in a statement.

Wheeler said the EPA is acting with urgency, pointing to a long-term PFAS “action plan” released earlier this year. But he said the agency must undertake a “rigorous” review before settling on national standards that are legally and scientifically defensible.

One of the most pressing splits is unfolding in the auto industry, as the EPA and the Transportation Department prepare to finalize a rollback of tighter tailpipe standards for cars and smaller pickup trucks. Last year, the Trump administration proposed freezing federal mileage requirements between model years 2020 and 2026, rather than boosting them to require that vehicles get more than 50 miles per gallon, as was required under Obama administration rules.

California, which has received federal waivers in the past to set its own rules, has pledged to press ahead with the tighter standards regardless of what the White House decides. Thirteen states and the District of Columbia are poised to adopt California’s standards if they diverge from the federal government’s.

Automakers, who pressed Trump to revisit the mileage targets as soon as he took office, are pressing the two sides to reach a compromise rather than fracture the nation’s car market. Two different standards could lead companies to market a small variety of more-efficient vehicles in some states while offering their entire fleet in others, said Alliance of Automobile Manufacturers spokeswoman Gloria Bergquist.

“That’s why there could be a stampede to buy popular larger vehicles in a neighboring state that follows the federal standard,” Bergquist said. “This is all new territory, so no one really knows how it will unfold, but it will be a headache for everyone involved, including consumers.”

Colorado and New Mexico are in the midst of rewriting the rules for how the oil and gas industry operates, such as limits on greenhouse gas emissions from drilling operations.

Colorado Gov. Jared Polis (D) recently signed a bill transferring a large portion of the state’s authority over drilling to local governments, and changing the orientation of its Oil and Gas Conservation Commission to emphasize public health and safety over extraction.

Even as the Interior Department has relaxed an Obama-era rule limiting methane emissions from drilling operations, Colorado is tightening its methane standards.

New Mexico, too, is drafting a new methane rule. Meanwhile, its land commissioner last month put nearly 73,000 acres in the northwest part of the state off-limits to drilling on the grounds that the area, known as the Greater Chaco Region, is sacred to the Pueblo and the Navajo tribes.

Interior had planned to auction off more than 4,000 acres of leases in the Greater Chaco Region last year but abruptly canceled the sale in the face of public criticism.

Robert McEntyre, spokesman for the New Mexico Oil and Gas Association, said in an interview that his members are used to dealing with both state and federal regulators, and are engaged in discussions about how to curb methane that leaks or is deliberately released and burned off.

“Across the board, every operator in New Mexico recognizes that limiting methane emissions while continuing growth is a top priority,” McEntyre said, adding that EPA data show overall methane emissions dropping by 4 percent in the Permian Basin, which straddles New Mexico and Texas, even as production doubled between 2011 and 2017.

Erik Milito, vice president of upstream and industry operations for the American Petroleum Institute, said the industry recognizes the role of the states as regulators. But he said some changes, such as Colorado’s new limits on drilling, go too far.

“The localities should not have the authority to ban oil and gas operations,” said Milito, whose group is now working with regulators to help shape how the new law is implemented. “They should have the zoning authority they already have.”