Shane Rattenbury was at South Durras on Wednesday night waiting for the bushfire now threatening the small coastal town.
The fire front was moving towards the hill from the north on the western side of the lake and was expected to round the bottom of the lake on Wednesday night.
Mr Rattenbury, the Greens leader in the ACT, said if it the winds turned westerly during the night as forecast, the village could be under threat.
At that point the road would be impassable.
"There's only one way in and if the fire comes that road will be blocked, so everyone will head to the beach," he said.
Mr Rattenbury drove to the coast on Monday night to defend his holiday house with his partner, forcing the Greens to cancel Thursday's announcement of candidates for the 2020 election.
He said about 50 people remained in the town on Wednesday night and the feel was "eerie" as they waited.
His house, which he described as a wooden shack, is close to the bush on the western edge of the town. He said he had spent the past two days clearing the property and preparing it, with hoses and buckets of water ready. Residents of South Durras have only tank water.
He is no stranger to defending homes against fire, having helped his parents save their Holder home in Canberra in 2003, when houses around them burned.
"It's an eerie feeling" he said.
"I went though the fire in Canberra in 2003 so I feel a combination of perhaps a sense of what we might be in for, but at the same time having no idea, because it's always different."
North Durras has taken the brunt so far, and on Tuesday night the fire had jumped the lake to the south side, where firefighters had beaten it back as residents in South Durras watched the orange glow.
Conditions were better on Wednesday, but were expected to be dangerous again on Thursday with hot temperatures and strong wind.
On Monday and Tuesday night, Mr Rattenbury set his alarm to wake him every two hours to check on conditions. On Wednesday night, he was planning still more vigilance through the night.