Googong Dam has been an experiment since 1975 to test whether recreational fishing can exist within a drinking water supply.

Hundreds of thousands of trout and native fish have been released into the dam as fingerlings and many of them pulled out for photographs and the dinner table.

Feral deer, pigs and illegal hunters and their dogs have roamed the foreshore, electric-powered boats have rippled the glassy surface and many more people are expected near the picturesque wildlife refuge.

"The first new homes for a town of 16,000 people are nearing completion. ACT head ranger at ownership and that's when you get that neighbourhood watch attitude going on," Mr Darcy said.

"They will get to know Googong well, the same as the rangers do and have an attachment here to the nature reserve." Mr Darcy is concerned that in summer, after school hours, bored children with matches could pose a fire threat.

So far park managers have maintained the Queanbeyan River valley's habitat for a growing number of echidnas and wombats, and a surge in birds following weed poisoning.

Sea eagles have lived there for decades and two pairs of peregrine falcons hunt in the southern and northern ends of the dam.

"For the first time in 30 years we have had both families produce chicks and actually fledged," the ranger said.

Canberra ecologist Bryan Pratt said in 1975 the Googong fishing experiment was a first for Australia.

"I fought tooth and nail to get Googong open for recreational fishing and boating and it is still the grand experiment in my mind. Other councils and jurisdictions have followed suit," Dr Pratt said.

"Because water goes into tertiary treatment after it leaves the reservoir, it should be safe for the population.There should be no harmful bacteria, viruses or nematodes, or other organisms coming out of Googong."

NSW Fisheries assistant hatchery manager at Narrandera Lachie Jess released 30,000 golden perch into the dam on Wednesday, watched by Dr Pratt, Mr Darcy and Monaro Acclimatisation president Steve Samuels.

Mr Samuels has seen large numbers of redfin perch dine on freshly released fingerlings. Mr Darcy, who has worked at Googong for eight years, says cormorants recognise the fisheries vehicle and tank arriving on the banks and ready themselves for a feed.

Abundant acacia around the banks will provide cover for the 10-weekold, 40-millimetre fingerlings, which should reach angling size after two or three seasons.

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Googong Dean Darcy is keen to make friends with early arrivals. "We want to create a friends of Googong group, who will come in on weekends for work parties, and from that [activity] they will feel

GETTING IN THE SWIM: Lachie Jess releases golden perch fingerlings into Googong Dam and, below, ranger Dean Darcy, who is keen to meet new residents. Photos: ROHAN THOMSON