Large numbers of brumbies will be shot from the air in the Australian Alps for the first time in years as their trampling of native wildlife trumps tradition.
NSW Environment Minister Penny Sharpe said she was reluctant to kill horses but the changed approach in Kosciuszko National Park was essential to protect threatened species and pristine ecosystems.
Numbers of the feral animals have boomed over the past decade and the state is on track to miss a legislated target to reduce numbers to 3000 by 2027.
"We've paused for too many years," Ms Sharpe said.
"The sooner we get the horse numbers down, the fewer horses actually need to be culled into the future."
A dozen species were already directly impacted by the park's estimated 18,800 horses, which had carved paths and trampled river banks.
"If humans were making that impact on a park, we wouldn't allow that. We have specialised walking tracks that keep people off it," Ms Sharpe said.
Environmental groups have long called for the use of aerial shooting, a move that was also supported at a federal parliamentary inquiry in early October which found brumbies posed an immediate extinction risk to native species in the Australian Alps.
Federal Environment Minister Tanya Plibersek backed aerial shooting as "a huge help" to reducing serious damage to parks from horses.
Feral horse numbers have exploded since then-NSW Nationals leader and deputy premier John Barilaro opposed culls in favour of trapping and rehoming in 2018.
Some forms of culling were reintroduced in 2021 in an effort to bring the population to a "sustainable" headcount of 3000 within six years.
But numbers have instead reached 18,800 in NSW.
Achieving the 2027 target would require about 6000 horse removals a year for five years, according to modelling for the Invasive Species Council - far higher than current rates.
Aerial culling of horses is legal but not used in Victoria while the ACT rarely resorts to it for the few brumbies it manages.
NSW allows the measure for other feral species, including pigs and deer.
An independent wildlife veterinarian and RSPCA NSW will be involved in the rollout of the horse-shooting program.
Relevant areas of Kosciuszko National Park will be closed when aerial shooting occurs.
But the decision will have wider consequences for state Labor as it loses a key left-wing vote that will narrow its ability to pass legislation.
Animal Justice MP Emma Hurst said it was difficult to see how her party could support a government that had failed to uphold any election promises for animal protection reform.
She and other animal rights activists don't agree with Ms Sharpe that aerial shooting can be carried out in accordance with rigorous animal welfare standards.
"When the last government-sanctioned aerial shooting of brumbies took place at Guy Fawkes (national park), horses were found days later still alive with bullet wounds," she said.
"This is the sort of bloodbath we will likely see again."
The loss of her vote would force Labor to rely on at least one vote from the right to pass any legislation opposed by the opposition.
The Greens strongly supported Friday's change in "rolling back the destructive and unscientific policies" of the previous government.
Aerial shooting also won 82 per cent support during public consultation, from the 9500 submissions commenting on the proposal.
"We believe this is representative of a broader shift in public sentiment as awareness of the impact of feral horses has grown," Nature Conservation Council of NSW chief executive Jacqui Mumford said.
