But Climate Change Minister Shane Rattenbury said "costs will reduce, as outages will not be needed" after a transition period of three to five years.

Responsibility for tree trimming around powerlines had previously been with Transport Canberra and City Services.

The cost of the management had been paid for out of rates revenue collected by the ACT Government.

However, the Utilities (Technical Regulation) Amendment Bill 2017, passed in the ACT Legislative Assembly last month, transferred the responsibility for the management of vegetation near powerlines on public and rural land, national parks and nature reserves to ActewAGL Distribution.

The utility can then apply to the Australian Energy Regulator to pass on the cost to customers.

ActewAGL Distribution confirmed it would apply to recover the costs for the work and expected pricing changes to begin mid-next year.

Rates will not decrease by a corresponding amount.

During debate on the laws in September, Mr Rattenbury, told the Assembly that the average Canberra household would pay extra $9 to $10 per year for the new urban tree management regime.

"The utility is confident that after a transition period of three to five years, the trees will be in a much more manageable state and costs will reduce, as outages will not be needed," Mr Rattenbury said.

"Some trees are dangerously close to the powerlines and require outages to prune them back to within acceptable clearances.

"The utility is confident that after a transition period of three to five years, the trees will be in a much more manageable state and costs will reduce, as outages will not be needed. "

Rules for residential properties will remain unchanged, with residents still responsible for keeping vegetation clear of powerlines on their property.

The Canberra Liberals unsuccessfully opposed the bill, with Member for Brindabella Nicole Lawder arguing the cost of living pressures meant the extra $10 would hurt a lot of Canberra households.

"Whilst Mr Rattenbury said ... in his speech that when trees are in a more manageable state costs will reduce, as outages will not be needed, I have yet to see any changes introduced by this government that lead to a reduction of electricity prices," Ms Lawder said in the Assembly on Tuesday.

"What we see time and again is a small increase and another small increase and another small increase.

"This change is going to see an increase for consumers. I do not understand what the benefit is going to be. All it is going to be is another charge to consumers. That is on top of every other charge that we see."

An ACT Government spokesperson said the change had been about keeping Canberra's power on.

"This bill protects the community from the risk of fire and power outages from vegetation hitting powerlines," the spokesperson said.

"That's why we've included a range of bushfire management measures, coupled with environmental protections, to ensure that minimum clearance distances for trees are maintained.

"This will help to ensure that the ACT does not experience a major preventable bushfire—like those experienced in 2003—and ensures reliability of supply during major storms."

The spokesperson said the change had been consistent with interstate practices and would provide greater consistency as the utility would assume responsibility for maintaining clearances from all their overhead electricity assets, except urban backyards and National Land.

The government also said the changes would ensure that the environment would be managed sensitively.

"A Technical Code to accompany the changes will include specific measures to manage potential environmental impacts, such as weed and pathogen spread, and the code will be overseen by the Conservator of Flora and Fauna.

"This legislation is partly driven by recent legislation in Victoria requiring improvements after fatal and catastrophic fires in that state.

"It is also part of ensuring we meet the objectives of our Strategic Bushfire Management Plan 2014–19."