Haligonians have a new bathing opportunity Saturday. The harbour is officially open to swimmers.

About as long as there have been toilets, Halifax dumped its sewage straight into one of the world's great natural harbours.

Walk along the waterfront and you could see unpleasant flushables in the murky water. Locals called them harbour squid, sea-mice, finless browns.

But now, thanks to a $333-million sewage treatment project, the water is sparklingly clear — so clear, the city says, that it had to hire divers to pick up some of the junk, shopping carts and beer kegs that used to line the bottom.

James Campbell, communications manager of the Harbour Solutions Project, said bacteria counts have plummeted.

"Well, the first plant in Halifax came online in November, and the results were dramatic," he told CBC News. "They came down quite quickly; within weeks, literally, they were in the guidelines, so it's really quite dramatic."

Now, lifeguard chairs are back for the first time in three decades.

Mayor Peter Kelly is playing host Saturday at beach parties in two spots where a swim used to come with the risk of a nasty skin infection.

The parties are at Black Rock Beach in historic Point Pleasant Park and Dingle Beach on the North West Arm.

Kelly, who has already taken an inaugural dip, said the water's fine.

"It's cool, it's clean, and most of all it's fun!"