There are fears Kosciuszko National Park within the iconic Snowy Mountains is being "carved away" by wild horses recently protected by the NSW government.
Much of the vegetation across the national park has been crushed, streams that used to be clear are now muddied and hoof marks from brumbies are "everywhere".
That's what former park ranger Kim de Govrik saw when he visited Kosciuszko National Park months after the a controversial law was passed protecting the heritage value of the wild horse populations in the park.
Mr de Govrik, who was a NSW park ranger for nearly 30 years, argues brumbies, like other "pest species" need to be controlled.
"Could you imagine the furore if they said they're going to protect pigs or something?," he told AAP.
Mr de Govrik, who's now a union organiser for the Public Service Association, used to fill his water bottle from the crystal clear water flowing in the park's many streams.
Now, he says he can't because stream banks have been trampled by the horses causing siltation - a type of sediment pollution.
The brumbies bill, passed in June 2018, drew criticism from environmentalists who argued letting numbers swell would result in mass starvation and damage to the iconic park.
With the ongoing drought conditions, there's even more competition between the wild horses for food and many are starving, Mr de Govrik said.
"When their feed is down, they struggle to survive," he said.
"(The bill) was a really poor error of judgement by the government."
Deakin University ecologist Don Driscoll warns the increase in feral horses could lead to the decline of several animal species as the horses destroy creek-side vegetation, cause stream banks to collapse and increase silt in streams.
The alpine water skink, broad-toothed rat, the critically endangered northern corroboree frog and equally endangered stocky galaxias fish are some of the species most at risk, Dr Driscoll said.
"The most environmentally devastating aspect of the bill is to give priority to feral horses over the protection of native biodiversity," he told AAP in a statement.
"What this bill does is legally carve away chunks of Kosciuszko National Park for raising feral horses."
An Office of Environment and Heritage spokeswoman said horse numbers are controlled by live trapping and they're rehomed where possible.
The brumbies bill recognises the heritage value of the horses while also recognising the environment needs to be protected, she told AAP in a statement.
Australian Associated Press