Police have struck a major blow to Wanganui's gangs, seizing more than 2000 cannabis plants in a major sting operation.
The plots, found in forestry plantations and dense bush up the Whanganui River, netted 2024 plants in the sting, dubbed Operation Kristy, earlier this year.
More than 11,000 plants were pulled overall in this year's cannabis recovery programme over the Central policing district, including 1500 in the Ruapehu area.
According to a combined team from police, Ministry of Health and Winz it represented an estimated saving of nearly $30 million in social harm costs.
Operation Kristy has put a significant dent in the cannabis trade with 257 people charged and in many cases jailed, say police.
Police could not provide a figure for the number of Wanganui or Ruapehu people charged.
About 100 police officers worked on the operation across the Central district.
Central district spokesman Constable Dave Kirk said that in Wanganui the cannabis hauled in came from plots run by the three local gangs: Hells Angels, Black Power and Mongrel Mob.
"We knew exactly who was doing what because we had many of plots under surveillance and could see clearly who was going there and how often."
The surveillance phase ran from last September when police were able to identify exactly where crops were being grown.
Police moved in to arrest offenders and pull out the plants in February and March, he said.
"Some raids made up the Whanganui River were by air force Iroquois helicopter with officers being winched in to the plots."
Mr Kirk said tip-offs about plots to police had come in from a number of people including farmers and a few calls had come from people driving along a backcountry rural road.
He said the good recovery results this year had not been entirely unexpected given the topography and good growing conditions in and around Ruapehu and Wanganui.
Even though the number of plants seized was down by more than a thousand on last year, the number of offenders had risen, he said.
"It's well-known and well publicised that we carry out this operation every year but some growers still seem to think they can operate under the radar.
"I'm sorry to say they are sadly mistaken because we're always going to catch up with them."
The aim every year was to track plots back to the growers and eradicate as many plants as possible, he said.
"The bottom line is we don't want drugs on the streets so even if we can't get the offenders pulling the plants has a significant impact."
The social harm that the cannabis trade creates is enormous, he said.
"Health, education, employment, the benefits system are all affected by the influences of drugs on people's lives … this sort of cost to society cannot be underestimated."
The national police operation saw more than 140,000 cannabis plants destroyed and more than 1100 people arrested.