THE state government has proposed making artificial reefs off Galgabba Point, Swansea, a permanent fixture.
Six reefs, each separated by 350 metres, have 100 reef balls each.
About 180 reef balls were lowered onto the lake bed in 2005 and a further 420 reef balls were added in 2009.
Lake Macquarie City Council's conditions of consent for the pilot project required the reefs' removal this year, or a new application to extend their lives or leave them in the lake.
The Department of Primary Industries has applied to the council to keep the reefs in place permanently. A department report said the reefs were a success.
"We found the artificial reefs were rapidly colonised by a diverse fish community, with 51 species observed over the two-year study period," the report said.
The reef project was mainly done for scientific research.
The study showed the reefs were "effective at extending the habitats of a variety of fish such as yellowfin bream, snapper and tarwhine".
Natural reefs near Pulbah Island and Wangi Point were compared with the artificial reefs off Swansea.
"Artificial reefs recorded a higher number of species (28), than natural reefs (21)," the report said.
Tarwhine, snapper and sand whiting accounted for 70 per cent of the recreational catch at the artificial and natural reefs.
Striped trumpeter and snapper were three-times more abundant on artificial reefs than natural reefs, but yellowfin bream were twice as abundant on natural reefs.
Popular with recreational fishers, the reefs were a "productive location where a range of recreational species may be targeted responsibly".
The department concluded that the artificial reef had a "negligible physical and environmental effect".
"The reef is now providing a complex and productive habitat for a diverse and abundant range of fish."
This was contributing to "the broader ecological diversity of the lake".