Prosecutions of environmental crimes have "plummeted" during the Trump administration, a new report said.

The first two years of the Trump administration had a 70% decrease in criminal prosecutions under the Clean Water Act and a decrease of more than 50% under the Clean Air Act, the Environmental Crimes Project at the University of Michigan law school found.

The research examined cases brought between 2005 and 2018, and the two-year period starting in 2016 had "the worst pollution prosecution numbers in the 14 years covered by our study," said study author David M. Uhlmann.

Civil prosecutions have also dropped significantly during the Trump years, and the administration has abandoned the long-standing practice of using settlements of environmental cases to require polluters to address past and future pollution problems with supplemental environmental projects.

The drop in prosecutions occurs within the larger context of President Donald Trump's hostility toward government regulation in general and environmental regulation in particular. Since his election, the administration has tried to roll back 100 environmental regulations, although many of these initiatives have not fared well in the courts.

The analysis notes that resources for environmental prosecutions have long been under pressure at the federal level, which has led to a gradual drop in the number of prosecutions, even during the Obama administration. The number of defendants dropped from 191 in 2011 to 106 in 2014.

"Under President Donald J. Trump the bottom fell out," Uhlmann wrote, "with just 90 defendants prosecuted during 2017, and 75 defendants prosecuted during 2018." In 2018, the administration charged only nine defendants under the Clean Water Act.

Environmental prosecution is a partnership between the EPA, which investigates misconduct, and the Department of Justice, which pursues the civil and criminal lawsuits.

Jeffrey Bossert Clark, who heads the environment and natural resources division of the Department of Justice, said the article "paints a misleading picture." A spokeswoman for the EPA said the agency "has reinvigorated its criminal enforcement program" and "reversed the downward trend" in cases.