A cannabis factory containing around 330 plants has been discovered at a house in Potters Bar.
Police believe the plants, which were found in Willow Way, to have a street value of about £90,000.
A 26-year-old man has been arrested on suspicion of being involved in the production of cannabis.
The discovery was made due to the sharing of intelligence between Police and Hertfordshire Fire and Rescue Service, as Sergeant David Perkins explains: "This is a great example of partnership working with our colleagues in the fire service to take action against the cultivation of drugs and the associated criminal activity.
"Cannabis factories are often linked to human trafficking, modern day slavery and the exploitation of society's most vulnerable.
"These factories use large amounts of water and electricity which are often syphoned from other people's supplies and can pose a fire hazard."
Sergeant Perkins continued: "If you suspect a cannabis factory is being operated in your neighbourhood or have any other information about drug cultivation or dealing, please let us know by calling the non-emergency number 101 or report information online at www.herts.police.uk/Report.
"If you'd like to remain anonymous you can get in touch with the independent charity Crimestoppers on 0800 555 111 or online at www.crimestoppers-uk.org."