A national surf sports event scheduled for the Illawarra later this month is under threat after wild weather caused extensive erosion at Bulli Beach.
Heavy rain and stormwater run-off "split the beach in two" after 174.2 millimetres of rain was recorded in nearby Bellambi on the weekend of November 4 and 5.
This is almost double the average rainfall for the month.
Large sections of the beach have been carved away, with some drops up to 1.5 metres deep.
The main walkway from the club to the beach is now dangerous, with large expanses of sand washed away and wooden planks left hanging without support.
Some of the nations' most promising surf lifesaving talents are set to compete, with around 1000 people expected to attend.
Competitors and the public would be at risk, Mr Caldwell said.
"The beach will fix itself naturally, but we will probably need to have a look at doing some temporary work to some of the areas just to level it out," he said.
"God knows what's in the debris."
Heavy rain and stormwater run-off in Bulli "split the beach in two", Surf Life Saving Illawarra duty officer Anthony Turner said.
"On Sunday, 11 beaches were closed due to beach erosion, debris washed onto the sand and poor water quality due to storm water run-off," he said.
"There was a lot of localised flooding. Clubs closed the beaches due to safety concerns."
Mr Caldwell said the landscape of Bulli Beach has changed significantly in recent decades, with the original promenade on the beachside of the surf club replaced by dunes.
"Because you've got those dunes there, that's then trapping that sand that organically and naturally gets pushed up onto the beach," he said.
Wollongong City Council workers have taped off some sections of the beach while more work, largely dune stabilisation and excavating the base of the lifeguard stand, will start on Tuesday.
A council spokesperson encouraged people to use the NSW Government's Beachwatch website so they can make saferchoices on where and when to swim.
Mr Caldwell said the dunes interrupt the sand's natural movement and the beach is now much higher then it once was.
"What we're actually seeing is the water running off and scarping through, back down to the natural level of what the beach really should be," he said.
In Shellharbour, no beaches were damaged during the wild weather however they were closed on Sunday due to poor water quality.
"There was some flash flooding impacting low lying roads in Albion Park and Warilla and they were closed for a short period early Sunday morning. Preliminary assessment indicate there was no significant damage to public infrastructure requiring repairs," a council spokeswoman said.
No beaches were damaged in Kiama, and council staff opened the mouth of Werri Lagoon as it reached the level required level on the weekend.
"This happens fairly regularly throughout the year as a result of heavy rain," a council spokesman said.
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