Georges River experts say the river's water quality will be affected for a while following this month's flooding and intense weather events.
Georges Riverkeeper program manager Beth Salt said water quality was the organisation's biggest concern in the wake of the floods.
"The water quality will be affected for some time given the amount of water that has moved through the system, bringing with it pollution from the urban landscape including litter, nutrients, sewage overflows and sediment," she said.
"Raw sewage is a particular concern and people seeking to enjoy the waterway should check in with the NSW Beachwatch Beach Pollution Forecast before going for a swim or paddle on the river, even now some time after the rain event."
Where past floods or rain events have caused damage to some of the species which call the river home, Ms Salt said the Georges fared well this year.
"Thankfully this time around we haven't received any reports of fish kills on the river," she said.
"During the rain event this time last year there was a significant fish kill affecting yellowfin bream and prawns.
"With so much water entering the system it is difficult to pinpoint the exact cause of these fish kills.
"However, quick changes in salinity, temperature and dissolved oxygen as well as chemical spills as a result of heavy rainfall can have devastating effects."
Ms Salt said Georges Riverkeeper was awed by the pace at which waters rose, particularly in the Warwick Farm area, and it was certainly a learning moment.
"The speed in which the water can rise is quite incredible," she said.
"On two occasions, it rose several metres within a few hours at Scrivener Street in the upper estuary and fell away almost as fast.
"People living and working within flood zones of the river need to be vigilant and follow warnings to avoid getting into trouble.
"Georges Riverkeeper would like to extend our condolences to anyone affected by the flooding within the catchment and elsewhere. The intensity and extent of the flooding has been overwhelming.
"We wish everyone who has been affected a speedy recovery."
Learn more: georgesriver.org.au
