Jerrabomberra Wetlands has been an oasis for birdlife and aquatic wildlife in Canberra since Lake Burley Griffin was filled in the early 1960s.

This year marks 25 years since the establishment of the nature reserve at the wetlands, a milestone being celebrated by environmentalists in the capital this week.

The wetlands stretch from Molonglo riverbank on Moreshead Drive to the edge of Kingston and Fyshwick in the south, and cover almost 200 hectares on the eastern edge of Lake Burley Griffin.

Environmental scientist Mark Butz said the Jerrabomberra Wetlands was one of Canberra's best kept secrets.

Environmental scientist Mark Butz said the Jerrabomberra Wetlands was one of Canberra's natural treasures. ( 666 ABC Canberra: Hannah Walmsley )

"It is the largest lowland wetland ecosystem in the ACT that is protected," he said.

"This is a very special landscape in the ACT, partly because it informs so much of the Canberra story.

"There is so many things that could have been done, or not done, that resulted in the water banking up into this landscape to create the nature reserve and haven for aquatic wildlife that it is now."

The Jerrabomberra Wetlands is recognised as an important wildlife habitat which supports a fantastic variety of waterbirds and other fauna and flora in the heart of Canberra.

Up to 200 bird species have been spotted in the wetlands, as well as platypus, turtles, eastern grey kangaroos and other wildlife.

"It is a highly variable boom and bust landscape," Mr Butz said.

"The attractiveness of this for wildlife is a mixture of standing water and vegetation that goes with that.

"It is also a vital stopover point for migratory birds that travel thousands of kilometres seasonally."

A rich history on fertile land

The highly fertile floodplain in the northern part of the reserve contains significant evidence of past movements of the Molonglo River and flood channels.

For thousands of years Aboriginal people lived and gathered food in the Molonglo Valley.

"Aboriginal people first lived in this area for upwards of 20,000 years," Mr Butz said.

"Earlier than that, there is speculation that parts of what is now the wetlands would've been underwater in an ancient lake up to 10,000 years ago.

"Later, Aboriginal people lived a very rich and fulfilling life in this rich landscape."

Early in the 19th century, European pastoralists used the fertile land for cropping and dairying.

"The property just below the adjacent Duntroon military base was originally owned by the Campbell family," Mr Butz said.

"Trooper Ainslie de-pastured about 700 sheep here in 1825 and formed the nucleus of what would later become Pialligo and the Duntroon property owned by the Campbells."

The area continues to be grazed to help manage the biomass of exotic pasture, but livestock has been excluded from some parts of the sensitive riparian areas.

Archaeologists only recently discovered the remains of 100-year-old trenches at the Jerrabomberra Wetlands, built by Australian soldiers preparing to fight in World War I.

Aerial of Lake Burley Griffin east basin in 1964 after the lake was first filled. ( Supplied: National Library of Australia 143742645 )

The arrival of Lake Burley Griffin

In 1963, Canberra's manmade Lake Burley Griffin was filled and by 1964 the wetlands had started to take shape.

"The lake water banked up into the wetland channels, into the Molonglo and Jerrabomberra Creek, and created permanent water where permanent water hadn't been before," Mr Butz said.

"The birds that had been gradually colonising the lake while it was being developed moved onto the flat and they've stayed on."

Just 3km from the city centre, the Jerrabomberra Wetlands continues to attract walkers, cyclists and pedestrians who pass through the sanctuary en route around Lake Burley Griffin's eastern shores.

The public has been invited to join in a community celebration to mark the 25th birthday of the Jerrabomberra Wetlands at 2 Dairy Road, Fyshwick on September 24 from 6-8:30pm.