People have been sighted swimming illegally in a pool of water in a quarry on the outskirts of Millicent.
The quarry adjoins the Lake McIntyre reserve and the activity has been reported by its management committee to Wattle Range Council.
It has also asked the council they consider erecting signage warning against the practice.
The swimming occurred when the Millicent swimming lake was empty.
Lake McIntyre has recorded relatively high water levels in 2023 with a current level of 1.75 metres compared to 1.2 metres at the same time last year.