Illicit drug use is rampant in the West Coast workforce, with methamphetamine the drug of choice, according to recent tests.
The West Coast use of methamphetamine - nearly twice the national average - has alarmed the Drug Detection Agency.
Figures supplied by the agency yesterday show 23.8 per cent of workers drug tested on the West Coast last year had tested positive for methamphetamine use; the national average is 14.3 per cent.
Chief executive Kirk Hardy said it was the highest recorded in New Zealand.
"It is alarmingly high and is a concern, as is the high number of synthetic cannabis tests that came back positive," Mr Hardy said.