The Googong Dam, when it reached capacity in September. Photo: Rohan Thomson

Googong dam has begun to spill again as Wednesday's wet weather pushed it to capacity, while chaos reigned on Canberra's roads.

The spills come as parts of Canberra received more than the city's June average rainfall in less than two days, getting doused with 42mm of rain since Monday night.

Water being released from Scrivener Dam on Wednesday. Photo: Graham Tidy

"Googong dam is currently spilling and current inflows to Googong Dam are approximately 250 megalitres a day and rising," an Icon Water spokeswoman said.

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Water levels at other territory dams are also getting higher with the Cotter Dam 81 per cent full and Bendora 94.5 per cent full as of Wednesday.

"Current inflows to all three Cotter catchment dams are estimated as 400 megalitres a day, which represents four days current consumption for the whole of Canberra and Queanbeyan," the spokeswoman said. 

A milk truck stuck on a divider on the Monaro Highway on Wednesday. Photo: Jamila Toderas

High dam levels at Googong have been an ongoing concern, particularly for Queanbeyan residents after a disastrous flood in 2010 which caused $1.3 million in damage.

A major nearly-1,300 megalitre spill in August last year, saw Queanbeyan City Council to seek assurances from the then ACTEW Water, Icon's former name.

On Wednesday Icon Water said the dam's current state was not a major problem.

Rain hit the city on Tuesday after a dry winter spell. Photo: Graham Tidy

"In the scale of things it is not really a large event. More importantly, this event prepares our catchments to generate good runoff in subsequent rainfall events. 

"This is particularly important at this time of year as late winter and early spring typically produce the best inflows to our dams," the spokeswoman said.

Road chaos came to a tragic crescendo on Wednesday with a fatal crash in Wanniassa.

While Canberra sports grounds will be closed on Wednesday, the Raiders still had to battle the elements on Tuesday. Photo: Graham Tidy

Among a number of other incidents, a milk truck became trapped for some time on a divider on the highway near Pialligo Avenue and a single car crashed at just before 1.30pm in McKellar.

Earlier, four cars collided on Barry Drive in O'Connor just before 9am, and another three cars collided on Long Gully Road at about 8.50am.

Further west, a single car crashed on Uriarra Road about 9.30am. 

Sullivans Creek at the ANU on Wednesday. Photo: Graham Tidy

An emergency services spokesman said no-one was seriously injured in any of these crashes. 

There could be more trouble to come, however with rain not expected to ease from Wednesday to Thursday night.

In response, all ACT government sportsgrounds had been closed to prevent damage, an ACT government spokesman said.

They will remain closed until at least Friday morning, when they will be reviewed.

Down at the Snowy Mountains, rain also battered the snowfields.

Thredbo resort spokeswoman Susie Diver said the snow was managing to hold up regardless.

A milk truck stuck on a divider on the Monaro Highway on Wednesday. Photo: Jamila Toderas

"The snow is holding up well as the base is very solid due to big snowmaking sessions over the past four weeks," she said.