Goats will be used for the second time this year as part of an "elite four-legged weed eradication team" on the shores of Lake Burley Griffin.

Used in a trial last year, the goats returned to the Yarramundi Reach area on Monday. The herd of 30 goats is already munching its way through the weeds including blackberries, black alder, willow and other undesirable plants.

The goats will spend three weeks at Acacia Inlet before being moved on to the Lindsay Pryor National Arboretum on the lake's west shore from November 26 to December 7.

Herder Elisabeth Larsen owns the Herds for Hire business and spends the days with the goats, supervising them and sometimes helping them get to harder to access weeds.

"They are the best staff - they will work 12 hours a day, they never complain, they’re always happy, they need a pat every now and then. These goats are having the time of their lives, they have a career, they get to travel," Ms Larsen said.

The goats are good for the job because they can access places that machines can't and their bodies can metabolise woody branches.

Unlike horses, cattle and sheep, goats break down the seeds of weeds in their digestive system, meaning the seeds don't re-enter the ground through their faeces.

"Goats are browsers, they are adapted to eat not only grass, but they can eat branches and leaves and trees in addition to grass. They have metablism which is designed to break down really course stuff, as a result they can remove and graze on the woody weeds we want to get rid of," Ms Larsen said.

"Last year’s trial of goats for weed control at Acacia Inlet led to a substantial time saving for the follow-up human work crews, reduced the environmental impact of clearing weeds and made it much safer for crews to access the waterline to implement control of an alligator weed infestation," National Capital Authority boss Sally Barnes said.

"Goats have a vast appetite and create far less soil disturbance than machinery and can tackle terrain that would not be safe for mechanical plant."

While the goats may look fun to pat, the National Capital Authority is advising people not to approach them unless their owner is on-site, as the fence will be electrified.

"For the safety of the goats, people walking dogs in the area are asked to maintain control of their dogs and keep them on lead," Ms Barnes said.