WASHINGTON—Nearly 400 workers have left the Environmental Protection Agency in recent days, the agency said Tuesday, a wave of departures that soon could take the agency’s staffing to its lowest point in almost 30 years.

The departures come primarily from buyouts offered as part of President Donald Trump’s efforts to fulfill a campaign promise of “tremendous cutting” at the EPA. His budget proposal in March suggested a 31% funding cut that would result in approximately 3,200 fewer jobs at the agency.

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