It's believed to be one of, if not the largest, hydroponic cannabis set-ups found in the south-west.

Detective Acting Sergeant Elissa Smith, of the Warrnambool police divisional tasking unit, said a warrant was executed about 10.30am Tuesday at a Sundale Road address.

Plants were found in the front lounge room which led to Powercor and Wannon Water officials being called in to assist.

By 1.30pm police were able to access the home and police botanists were also called in to assist in the collection and weighing of the plants, which ranged in size from seedlings to mature.

Detective Acting Sergeant Smith said it was a highly sophisticated hydroponic set -up, involving a large number of high-powered lights, 180 transformers, as well as a watering and nutrient system.

The operation was in every room except the kitchen and one bedroom.

"It was capable of producing large amount of drugs. We don't know how long the grow house has been in operation," she said.

"There's a large amount of forensic work and investigations to undertake to identify persons of interest.

"We'll also have to wait for Powercor inspectors to try and give us an estimate of how much electricity has been stolen."

Warrnambool police divisional tasking unit members, crime investigation unit detectives, crime scene officers and uniform officers assisted in the collection of the plants.

Tuesday night: Police have seized about 300 cannabis plants with a potential street value of more than $500,000 from a grow house in Warrnambool's Sundale Road.

Detective Acting Sergeant Elissa Smith, of the Warrnambool police divisional tasking unit, said a warrant was executed about 10.30am Tuesday and plants were found in the home.

Powercor workers were called in and it was found there was an electrical bypass on the house.

Detective Acting Sergeant Smith said plants were found in every room of the house - about 300.

Mature cannabis plants have a street value of about $2000 each.

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The plants were about one metre high and well on the way to being mature.

Tonight State Emergency Service volunteers were setting up lights to assist while police officers were dismantling the hydroponic set-up in the home.

Botanist police officers were called in from Melbourne to assist with the operation, counting and weighing all the plants.

"On arrival this morning it was straight away observed there was a hydroponic cannabis growing set-up in the front lounge room and Powercor and Wannon Water were called in," she said.

"Entry was made to the home about 1.30pm.

"Since then we've been pulling it apart. All rooms have got hydroponic set-ups, except the kitchen and one bedroom."

The detective said the set-ups including lights, water and nutrients, were all set on timers.

"No one was here at the time the warrant was executed so investigations are still ongoing," Detective Acting Sergeant Smith said.

"We received information from the public that this was a suspicious address which led to investigations and the application for a warrant.

"The house was unkempt, there was never anyone here. This is the biggest crop I've seen. I haven't seen a set-up like this before. It's a complete grow house."

Detective Acting Sergeant Smith requested anyone with information about drugs to contact Crime Stoppers on 1800 333 000.

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