Colligan also pleaded guilty to two counts of supplying ecstasy and two of supplying LSD but the Crown has conceded that these drugs were given to his "workforce" so the supply was for non-commercial purposes.
"A bit like providing biscuits and tea," Judge Neave said, while granting bail but warning the accused that prison was inevitable.
Operation Marvel culminated in December 2008 when more than 30 marked and unmarked police cars and an Iroquois helicopter swept on houses in Westport, Waimangaroa and Cape Foulwind.
About 90 police officers took part, busting what police described as a multi-million dollar commercial drug syndicate.
Police had spent 14 months on the case and used phone taps, secret cameras and undercover officers.
Cannabis was grown near Westport and Reefton and prepared for sale in Buller, then sold in Nelson, Canterbury and Wellington.
In total there were 15 arrests from Operation Marvel but all other defendants have already been sentenced, some to jail and others to community-based sentences.
One Westport couple was also ordered to pay $30,000 to police as profit forfeiture, under the Criminal Proceeds (Recovery) Act, 2009.