James Campbell, speaking for Halifax Water, said 90 per cent of people under the evacuation order left last night by 11 p.m.
"As far as I know everything is going as planned. The contractors plan to start work at 9 o'clock this morning," he said.
The work is expected to wrap up by suppertime Saturday.
Campbell said the fish ladder at the Lake Major dam was damaged during the heavy rain event on Dec. 10. The fish ladder is a passageway for fish to bypass the dam.
Bridges over Highway 107 and Highway 207 are open today.
But four other bridges in the area are closed.
There are warming centres open for people who had to leave their homes. They are the East Preston Recreation Centre and the City Heights Church in Westphal.
The homes under the evacuation order are near the Salmon River, which flows from Lake Major. The affected homes are located in North Preston, Cherry Brook, East Preston, Westphal, Lawrencetown and Cole Harbour.
"It's been pretty smooth so far. People have been understanding, very cooperative. This is just a precaution, we're just hoping for the best," said Coun. David Hendsbee.
Cody Faught and his dog Karm went to one of the warming centres Saturday morning.
"I didn't want to leave her by herself, she might get a little bit upset," he said.
A few Halifax Transit buses have been brought in to keep pets out of the cold.
CBC News is at the scene and reporting the latest on the situation.