Swimmers have been given the all clear to dive into the waters of Lake Burley Griffin.
But the National Capital Authority has reminded the boating public of restrictions on the type of engines that can be used on the waterway.
As pleasure boats took to the lake in Thursday's sunshine, it warned that generally only craft driven by electric engines were allowed on the lake.
A water quality update, published on Thursday, found algae levels posed no problems for a swimmers, though the report showed that four of the eight lake zones recorded elevated bacterial levels.
Further samples were taken at East Basin, Ferry Terminal, Lotus Bay and Weston Park East on Thursday and the results were expected on Saturday.
If the levels remain high those zones will be closed for swimming, but will remain open for fishing, canoeing, and rowing.
The authority's chief executive, Gary Rake, said bacteria levels often spiked after storms such as those that swept Canberra on Christmas Eve.
He said the stormwater washed debris, such as duck faeces, into the lake, causing temporary leaps in bacteria numbers. But even if the four areas were closed, Mr Rake said popular swimming spots at Weston Park West, Black Mountain Beach, Central Basin and Yarralumla Beach would be open to bathers.
Water police, based in Yarralumla, patrol the lake regularly checking boat permits.