The Environmental Protection Agency (EPA) says it is "directing its resources to the most significant and impactful cases" but I think it would be more fair to say they're directing resources to hardly any cases at all.
Government records obtained through the Freedom of Information Act (FOIA) show that the EPA referred as many cases for criminal prosecution in 2018 as they did when I was 4-years-old.
From NBC News:
[The] 166 cases referred for prosecution in the last fiscal year is the lowest number since 1988, when Ronald Reagan was president and 151 cases were referred, according to Justice Department data obtained by the nonprofit Public Employees for Environmental Responsibility advocacy group and released Tuesday. [...]
Asked for comment, EPA spokesman John Konkus pointed to the civil settlement of about $800 million with Fiat Chrysler over claims the automaker rigged its diesel-powered Ram and Jeep vehicles to cheat on emissions tests.
Action against Fiat Chrysler and other car companies such as Volkswagen who've cheated on emissions tests was initiated by the Obama administration.
I doubt anyone believes for a single second that the Trump regime would have pursued those cases on their own and they certainly won't have anything similar to point to when 2019 comes to an end.
Considering that the EPA is currently idled by Trump's government shutdown, I don't think we should be surprised if even fewer cases are referred for prosecution this year.