Australia Weather News

The weekend's storms may have underwhelmed some Melburnians, but when it comes to their effect on the Yarra River there is good news and bad news.

The Victorian capital escaped the worst of the state's "rain event", which hit hardest in the north-east.

Yarra riverkeeper Andrew Kelly said the lesser downpour meant the Yarra's baby platypuses appeared to be safe and sound.

The bad news is the storms were large enough to flush the river with human faeces.

First, the good news

In Victoria, platypuses mate between August and October, after which the pregnant females build deep and complex burrows or renovate another female's burrow from a previous year.

It is in these specially constructed burrows that the mothers lay their eggs and suckle their hatchlings.

Before the storms Mr Kelly was concerned the burrows along Melbourne's main river would be flooded, drowning the babies.

"The burrows are in the bank, positioned above the waterline," he said.

"Platypus can only be under water for a few minutes at best.

"The risk was that the burrows would be flooded, but I'm confident that didn't happen because there was no extreme rise in water level."

Previous Melbourne floods had taken their toll on the Yarra's platypus population.

"After the 2011 floods there weren't as many juveniles for the next year or so," Mr Kelly said.

Now for the bad news

Mr Kelly said while some rises and falls in the river was natural, what was unnatural was the very sudden runoff flooding into the river from carparks, roads and driveways.

"The river is really turbid at the moment," he said, adding that the turbidity was bad for the river's ecology because "the murkier the river the less light gets to the bottom".

Mr Kelly said while the river's litter traps had done a good job of collecting the rubbish washed in by the storm, there were some contaminants the traps could not catch.

"Stormwater puts a lot of pressure on the sewerage system," he said.

"Water will leak in, the sewers will fill and water will leak out again under pressure."

He said there were still illegal sewerage systems along the Yarra leeching effluent into the river.

Further up the river there were also many properties with septic tanks that may have flooded and seeped into the river.

It's not just the Yarra; the Victorian Government website lists all of Port Phillip Bay's beaches as having poor quality water that is unsuitable for swimming at the moment.

An EPA alert advised the public to avoid contact with the water in Melbourne's waterways, including the Yarra, until further notice.

"Don't stick your hands in it, don't go paddling," Mr Kelly said.

"You get a lot of spray, you get water on your paddle, you get a lot of risk of getting infected.

"Last time I went paddling after a storm I got sick."

Hopefully the water is a little cleaner by the time the baby platypuses emerge from their burrows in a few months' time.

ABC