Western Australia's fastest growing local government area is at a crossroads.

Key points: Mandurah's population will swell to more than 120,000 in 2036

Mandurah's population will swell to more than 120,000 in 2036 Planning is underway to balance increased density and environmental conservation

Planning is underway to balance increased density and environmental conservation The local council is buying bushland from developers to retain for the community

Once a small holiday town with some hardy, long-term residents, Mandurah in Perth's south has experienced aggressive growth.

The city's population has exploded from around 30,000 to 90,000 over three decades, and that number is expected to grow to 120,000 by 2036.

At the centre of the dilemma is the balancing act being maintained by the local planning authorities, which must cater for a growing population while also trying to maintain the very reason why people move to Mandurah — the natural environment.

People were drawn to Mandurah in the 1980s and 1990s due to its easy-going lifestyle and natural setting. ( ABC News )

Today Mandurah is an extensively developed satellite city of Perth. ( ABC News: Marcus Alborn )

Delicate balancing act ahead

Chair of the Peel Development Commission, Paddi Creevey, said there was a big task ahead.

"What the challenge is, is how do you make sure that in accommodating that population growth we also accommodate employment for those people so that we have the economy that's working well," she said.

"And we also make sure that the environment — which is such a big attractor and so important to the social and economic life right through the region — that we make sure that's preserved into the future."

Paddi Creevey said there was a good opportunity to implement proper planning. ( ABC News: Benjamin Gubana )

Ms Creevey said careful planning was necessary to sustain the relaxed lifestyle of the region into the future.

"We get used to a particular kind of style, but we also know that has to change and accommodate the changing needs," she said.

"So what we have probably not done so well in the past is have the mix of accommodation styles and I think there's a lot more focus on that.

"I think also with better design you can make sure that you have liveable areas but you don't have that sense of overcrowding."

Trying to preserve a changing city

The State Government has tasked the City of Mandurah with finding a minimum of 14,510 extra dwellings by 2050.

Mayor Rhys Williams said recent population growth had changed the face of Mandurah dramatically.

Mandurah's population was a little over 30,000 in the 1990s. ( ABC News )

The City of Mandurah has been tasked with creating more than 14,000 extra dwellings by 2050. ( ABC News: Marcus Alborn )

"We're really proud of the fact that people want to continue to come and live and be here in this great city," he said.

"But that sort of population growth does change the dynamic and the complexity of a place like Mandurah, and we're always conscious of that."

Mr Williams said the bush buyback policy was well supported in the community. ( ABC News: Benjamin Gubana )

In 2006, the city noticed the predicted growth and began a policy of buying bushland off developers to retain for community use.

"A very wise council about a decade ago brought in the Buy Back the Bush policy," Mr Williams said.

"We're still the only local government in Western Australia that puts money into a reserve fund every year and goes out and purchases key pieces of land from developers.

"Some of the land that we've bought is the land around the entry coming along Mandjoogoordap Road into Mandurah.

"It's not just about retaining the bushland, it's also about immersing people in that bushland.

"So we have bushland officers that work in those spaces to make sure they are maintained as really special places for the community to enjoy."

'Don't wait for everything to get destroyed'

Local Indigenous elder Harry Nannup said it was important to preserve native bushland because it could not be recovered once developed.

"Once you do the damage, that's it," he said.

Local governments juggle population growth with environmental conservation. ( ABC News: Benjamin Gubana )

"Some of the wetlands we've lost because of money, I mean you get developers come in and they want to take the wetlands away, and they're going to be sorry for it one day.

"Because it's not going to stay wetlands for long.

"Act now, don't wait for everything to get destroyed."

The council was planning to purchase another parcel of land from developers within the next 12 months, with a goal of buying 150 hectares in total.

The City of Mandurah hopes to obtain 150 hectares of bushland through its policy. ( ABC News: Benjamin Gubana )

"The biodiversity that we rely on for our human life, that's under threat," Ms Creevey said.

"So how do we make sure that the children of today and tomorrow understand what this beautiful environment looks like?

"If it all goes for residential or is cleared, then we lose that biodiversity forever."

Holding off the Gold Coast image

Mr Williams said the City's growth brought several opportunities.

"I think people in Mandurah recognise that, as it has done for the last decade and a half, it will continue to be a place that grows, so that's our opportunity," he said.

Mr Williams said Mandurah's growth brought both challenges and opportunities. ( ABC News: Benjamin Gubana )

"How do we make sure that we shape the city in terms of density targets in our city centre, that retains that thing that people love about Mandurah — that natural beauty, that relaxed lifestyle?

"The last thing that we want to be doing is seeing Mandurah take on a Gold Coast-type feel to it.

"And so we're going to grow, but we have to grow in the right way."