Scott Pruitt resigned from his job as EPA administrator Thursday amid more than a dozen ethics scandals and investigations into his spending, energy industry ties, and secrecy. But the reforms he’s implemented at the agency will leave a legacy for years to come.

In the last 18 months, the Trump administration has attempted to cancel or roll back more than 70 environmental rules. And as EPA administrator, Pruitt made a major contribution to this anti-regulation agenda. From Day One, he launched an attack on climate science and policy that included scrubbing public information on climate change from agency websites and stopping implementation of the Clean Power Plan, a flagship policy to limit emissions from coal-fired power plants. Pruitt also enthusiastically backed President Trump’s decision to withdraw the U.S. from the Paris climate agreement.

But he was just getting started: Pruitt took on the Clean Water rule, tried to lower fuel-efficiency standards for vehicles, removed a prohibition on toxic water discharge from power plants, and missed the deadline for implementing smog-fighting ozone limits. He also overturned a ban on the carcinogenic pesticide chlorpyrifos.

“Every one of the things he tried to roll back had a benefit in terms of human health and the environment. So rolling those back is hurting Americans,” said Michael Mikulka, president of the Midwest region EPA workers’ union.

Still, the most lasting blow to the EPA could simply be Pruitt’s campaign to defund and destaff the agency’s programs. In the 2019 budget proposal, he suggested the agency take a 23 percent budget cut and pushed to kill programs — including ones aimed at cleaning up the Great Lakes and preventing children’s exposure to lead — in an attempt to make up for a $2.5 billion funding gap.

With the number of employees now down to the lowest level in 30 years, the EPA is also increasingly incapable of enforcing the laws that remain. Because the agency needs to catch and fine perpetrators to fund cleanup, reducing its workforce is a significant blow. The EPA is already issuing fewer citations and fines; it ordered just $1.6 billion in fines last year, one-fifth of the amount in 2016.

As a result, American environmentalists increasingly see litigation as the only way to win against an EPA leadership that takes meetings with industry and excludes scientists from decision-making.

Many of the administration’s recent rule changes have been challenged in court, and Pruitt’s EPA suffered more than a few defeats: in March, for example, courts ruled that Pruitt illegally delayed a decision on pesticide regulation. Another court stopped him from rolling back a rule on mercury pollution.

Still, even successful legal challenges are no guarantee that Pruitt’s effect on the agency can be undone, because of scrapped budgets and the steady flow of qualified staff leaving the EPA. And with Pruitt’s second-in-command and former coal lobbyist Andrew Wheeler taking the wheel, Trump’s EPA is set to continue its current path of deregulation.