Donna Stepan had been in Australia for less than a year when she saw a white ute deliberately swerve to hit a wombat who was grazing near Braidwood.

Although she rushed to help the injured animal there was nothing she could do for him.

"All I could do was sit with him and wait for him to die. I never ever wanted to be in a situation where that could happen to an animal and I just promised myself from that day onwards I would help them until the day I die, and I'm going to," she said.

But as numbers in her sanctuary continue to grow, with 23 wombats now calling it home, Mrs Stepan has turned to the community for help protecting Canberra's natural fauna.

She has launched a Pozible campaign with a target of $20,000, with which Mrs Stepan hoped to build a new enclosure and keep her service running.

She said it cost her and her partner, Phil, more than $35,000 a year to run the facility, all out of their own pockets.

Arriving in Canberra from South Africa in 1999, Mrs Stepan started volunteering at the RSPCA shortly afterwards – within a year she took in her first injured wombat, who she named Rustle.

She said one wombat turned into six at which point she had to move out to Gundaroo to accommodate them. When her colony grew to 12 she created the Sleepy Hollows Wombat Sanctuary.

Mrs Stepan said her sanctuary had an average of 20 wombats at any one time, as the number of animals injured on NSW roads and confiscated in animal cruelty cases began to surge.

"The world's gone mad and they take it out on the animals ... We've had 12 cruelty cases and confiscated pet wombats this year alone; normally we get one or two a year. The cruelty cases are getting worse," she said.

She said often had to collect pet wombats which people had taken in as babies, not realising how large and dangerous the animals can become in later life.