The legal limit for drivers aged 20 and over is 250 mcg.
"That result is well over treble the adult limit and, had our officers not intervened when they did, there's no telling how that journey might have ended for her, her passengers or others using the road," said Mr King.
"It beggars belief that parents could choose to put such precious cargo as their own children in such vulnerable situations."
Police had referred the incident to Child, Youth and Family.
"Adults need to take responsibility for their decisions and ensure that they don't put children, who have no input into such decisions, unnecessarily in harm's way."
As well as the driving ban, Waitea was fined $400 and sentenced to 8 months' supervision.
Under New Zealand law, all children under 7 must use an approved child restraint appropriate for their age and size.
Youngsters aged 7 must be secured in a restraint if one is available in the vehicle.
