The National Capital Authority received reports on the bacteria levels in the water this morning, which confirmed the lake could safely be reopened to all sporting and recreational uses, including swimming.

The lake had been closed since March 1, after Queanbeyan Sewage Treatment Plant went on bypass operations, sending partially treated sewage into the Molonglo River.

While the bacteria levels have now been deemed safe for lake users to jump back in, the NCA is still advising caution due to the high levels of debris left in the water from the flooding rains that drenched the region at the beginning of the month.

Although debris is generally smaller in both size and quantity than in previous floods, an NCA spokeswoman said the cleanup could possibly be complicated by lake levels that had been lowered to allow for repairs to Scrivener Dam, making it easier for debris to snag in the lake's floor.

"Now that the bacteria levels are in safe parameters for central basin and eastern basin, we are able to get our boats in now and assess the damage and work out how we are going to pull out the debris," the spokeswoman said.

The clean-up is expected to cost the NCA up to $100,000.