Three-year-old springer spaniel Freya has been trained to spot the nocturnal amphibians by trainer and ecologist Nikki Glover.
It is an offence to damage or destroy their environment without a licence from Natural England.
Glover said: “The Wessex Water region is a stronghold for great crested newts and we come across them when carrying out construction works.
“If works are within 250 metres of breeding ponds and we are likely to cause an offence under the legislation, we must apply for a licence from Natural England.
“We would then be required to fence off the construction area and carry out pitfall trapping (buckets sunk into the ground), which could take around 30 days to complete.
“Having a great crested newt detection dog within a utility company is a massive benefit because they can find the newts more efficiently and effectively, and it’s a non-invasive method.”
Great crested newts are the UK’s largest newt species.
They are found in breeding ponds from mid-March to mid-June, and the rest of the time they can be found commuting and foraging along hedgerows, grasslands and woodlands.
They are a nocturnal species so seek refuge during the day in stone walls, log piles and cracks in the ground.