On the eve of summer, Melburnians are being warned they could get sick from a dip in the bay or a splash in the Yarra thanks to the La Nina weather alert.
Australian meteorologists have declared a La Nina weather event is underway, with the country's wettest spring in 10 years to continue into summer.
On Tuesday, the Environmental Protection Authority warned Melburnians will need to check water quality before going for a dip in a bid to fight off the chances of getting gastro or other bugs.
The rains a La Nina brings can wash unseen pollutants off streets, into the drains and out into Port Phillip Bay and river systems.
"Run-off can often contain harmful microbes that can cause skin irritations, eye and ear infections, and even gastro illness especially for our kids, elderly and people with vulnerable immune systems," EPA Water Scientist Paul Leahy said.
Pets aren't safe either, according to Mr Leahy, who says they can often get skin irritants from water.
"Give them a good hose down after they've been in for a swim."
The EPA posts twice-daily water quality updates under Beach Report and Yarra Watch on their website.
EPA'S TIPS FOR AVOIDING GETTING SICK AT THE BEACH:
* Avoid swimming near stormwater drains
* Avoid swimming for 48 hours after rain
* Try not to swallow water during recreation
* Cover cuts and scratches with waterproof bandages
* Wash your skin with soap after touching the water and shower after swimming
