Excess breath alcohol readings of 1237mcg and 1550mcg in the past week have alarmed Oamaru police.
At 5pm on Tuesday afternoon, a 60-year-old man was processed for drink-driving in Hampden after allegedly blowing 1550mcg. The legal limit is 400mcg of alcohol per litre of breath.
The man attracted the attention of police after driving slowly on the state highway through Hampden.
He will appear in the Oamaru District Court on November 28.
Oamaru police Senior Sergeant Jason McCoy said the level was "extremely appalling".
"That's almost four times the limit, so that's a danger to all road users."
The incident was the second occurrence in the district in the past week, with a 52-year-old man being pulled over in Hampden with an alleged breath-alcohol level greatly exceeding the legal limit on Friday.
He blew a "staggering" 1237mcg and was suspended instantly for 28 days.
Mr McCoy said the high levels were "extremely alarming".
Mr McCoy urged people to report any suspected drunk drivers to the Oamaru police on (03) 433 1400.