The trough could be filled in if a tropical cyclone came and shifted sand around, but if that did not happen Mr Sefton said it would likely stick around for the rest of the season.
Rescue numbers this season were well ahead of last year, likely because of the trough combined with the swell at the beaches.
The trough had skipped Mount Main Beach, although swimmers still needed to be cautious.
Mr Sefton said beachgoers had generally been well behaved this summer, although some people were still "not really thinking" and putting themselves in dangerous situations.
"They're going in past all the signs warning about rips and into dangerous areas that have been clearly marked.
"There are groups of people choosing to swim outside the flagged areas where it would be only 100m to get to the flags, then getting into trouble."
There had also been several minor rescues involving people swimming in clothes rather than swimwear.
Mr Sefton said around the country several rescuers had got into trouble trying to help someone and had lost their lives.
"If you don't have the skillset to save someone, call 111 or one of the local surf clubs. If you're determined to go and help someone, take a flotation device like a body board so when you get to the person in trouble they have something to hold on to until help arrives."