The annual illegal drugs haul in Northland equated to more than $100 million in social harm last year and police expect the same result this cannabis-growing season.
The shocking statistics have been released as the Northland growing season starts, and police are urging anyone with information on drug operations to contact them.
The social-harm figure is based on the Drug Harm Index which has been designed to help police and other agencies concentrate resources in areas where greater harm is caused by illicit drugs.
Business and Economic Research Ltd (BERL) developed the index and like models used in Australia and Britain, it highlights the economic costs of the social harm drugs have on society.
The harm relates to a variety of costs linked to crime, lost work output, health service use, court and prison costs.
It also includes psychological costs such as reduced quality or length of life.
In last year's national crime and cannabis operation (Operation Kelly), Northland police destroyed 40,158 plants and made 108 arrests.
They also recovered $51,000 worth of stolen property, and located 13 indoor growing operations, one methamphetamine lab, 15g of methamphetamine and 6kg of dried cannabis.
That equated to $107,678,070 in social harm.
Northland Detective Sergeant John Miller, who heads the annual cannabis recovery operations, said the figures showed how much of a blight cannabis and other drugs were on Northland's communities.
"This is why police continue to target the people who grow, manufacture and supply illicit drugs. In order to reduce the harm caused by these drugs and the cost to Northlanders, we want the public's help in flushing out the dealers and growers," Mr Miller said.
BERL research leader Adrian Slack said the social harm was calculated by estimating the cost that would have been caused if the drugs made it on to the street.
For example, the cost per kilogram of cannabis was $12,000. Stimulants or methamphetamine caused $400,000 of harm per kilogram.
He said crime included the cost of police operations, stolen property to fund drugs, and custom operations right through the court process to probation services.
Associated health costs also included the admittance of babies due to birth defects caused by drugs, drug overdoses, and the use of pharmaceutical drugs to manufacture illegal drugs.
Last cannabis season police received plenty of information through the Crimestoppers number that led to successful search warrants.
Mr Miller said information given through the number remained anonymous.
"We would like accurate and detailed information, such as locations of growing operations or methamphetamine labs and names of people involved."
Retailers, particularly rural supply companies, needed to be on the look-out for people who were not regular customers buying large amounts of fencing equipment and plant nutrients.
If anyone has information relating to cannabis growing or dealing, they can contact their local police station in confidence or call Crimestoppers on 0800 555 111.