Ms Ley is examining how federal environment laws could be used to conserve the park's plants, animals and waterways, which have been under threat by the thousands of brumbies which roam Kosciuszko's wide expanses.

ACT Land Management Minister Mick Gentleman has welcomed Ms Ley's stance, which comes more than two years after he first wrote to her predecessor urging the Commonwealth to step in.

There were an estimated 14,000 horses in the park according to a 2020 survey, about 5000 fewer than in 2019 but well above levels at the turn of the century.

NSW Deputy Premier John Barilaro spearheaded a 2018 bill to protect the park's feral horse population, but has since reportedly changed his tune and accepted brumby numbers should be cut back - possibly to as low as 600.

Ms Ley earlier this year backed the NSW government's intention to cull horse numbers, saying the environmental concerns were "real and needed to be addressed".

But she went ever further on Wednesday after she asked to comment on the issue following an address to the National Press Club.

Ms Ley said her appreciation of the park's natural beauty dated back to when, as an 18-year-old, she rode on horseback through Kosciuszko on a trip from Yass to Ninety Mile beach in Gippsland.

"Wind the clock forward and seeing the damage that feral horses have done to the park now makes me extremely angry," she said.

Ms Ley said she would "love" to find a provision within the federal Environment Protection and Biodiversity Conservation Act that would allow the Commonwealth to effectively compel states to better conserve national parks such as Kosciuszko.

Ms Ley admitted that her anti-brumby stance could make her unpopular with people in her regional electorate of Farrer, as well with some of her Coalition colleagues.

She did, however, suggest that her cabinet colleague and Hume MP Angus Taylor shared her view.

She encouraged others to "make their voices heard" amid the bitter and divisive debate over the iconic animal's presence in the park.

Mr Gentleman told The Canberra Times he was pleased Ms Ley had recognised the damage feral horses were causing in national parks.

He first wrote to Ms Ley's predecessor Melissa Price in 2018, and then again in 2019, urging immediate Commonwealth intervention to "protect these nationally important ecosystems".

Mr Gentleman on Wednesday challenged his federal counterpart to "stay the course" and not be deterred by potential pushback from her Coalition colleagues.

"Every month that passes without appropriate management means more damage to our precious habitats and water catchments," he said.

"The longer horse numbers are left to grow the harder they will be to bring under control."

The Berejiklian government is expected to release a new draft plan to manage horse numbers in Kosciuszko before the end of the month.

A major reduction in horse numbers could head off any federal intervention.

Ms Ley used Wednesday's speech to express her determination to push through contentious reforms of the environmental approvals process, which were drafted in response to Graeme Samuel's scathing EPBC review.

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The changes would see decision-making powers devolved to the states and territories, under bi-literal agreements with the Commonwealth.

A set of national environment standards would underpin the agreements, which would be monitored by a new watchdog.

Labor wants the government to go back to the drawing board on changes it has rubbished as a rehash of Tony Abbott's 2014 proposal, while the Greens have described it as "legislation for extinction" of Australia's native species.

With the fate of the reforms set to rest with key senate crossbenchers, Ms Ley warned that environmental protection efforts would be harmed if the changes weren't passed swiftly.

"Make no mistake, if we do not get the process moving it will end up hurting both the environment and the economy," she said.