Sea level rise sets back Perth coastal development

The north Two Rocks plan covers land between Dewars Track and Wilbinga Nature Reserve. Picture: David Baylis d495054
The north Two Rocks plan covers land between Dewars Track and Wilbinga Nature Reserve. Picture: David Baylis d495054

RISING sea level predictions were the focus of a landmark legal decision on a coastal development in Perth’s north.

The State Administrative Tribunal (SAT) decision said development plans for north Two Rocks needed a foreshore reserve that could accommodate a coastline shift up to 171m inland over the next century.

Developers Two Rocks Investments, New Orion Investments and Atlantis @ Two Rocks appealed to SAT after the WA Planning Commission conditionally approved a local structure plan with 29 modifications for the 834ha site in 2016.

The plan covers land north of the existing town site, including 2.6km of coastline stretching from near where Dewars Track reached the beach to Wilbinga Nature Reserve and the metropolitan border between the City of Wanneroo and Shire of Gingin.

The developers appealed conditions relating to the coastal portion, where a former landowner had already given land to the Crown for a foreshore reserve in 1997, and sought permission to develop temporary special coastal areas.

“This case is of significance in relation to coastal foreshore planning in WA in the era of climate change and consequent predicted sea level rise and other coastal processes,” the tribunal said.

It said the coastline shift meant by 2120 the Indian Ocean was likely to occupy all of the existing reserve and another 9.93ha inland.

“The landowners recognise that the portion of the land which is vulnerable to coastal processes over the 100-year planning timeframe will ultimately need to be ceded to the Crown,” the tribunal said.

“However, they wish to be able to develop and use that land in the interim as it is only likely to be vulnerable in 50 to 70 years’ time.”

SAT ruled land that would be vulnerable by 2120 should be designated foreshore reserve, except for two special use coastal nodes, which developers would have to cede to the Crown for free when the coastline was 40m from the sites.

It said the need for a bigger foreshore reserve resulted from “climate change and developments in climate science and planning policy since the existing coastal foreshore reserve was ceded”.

The tribunal said the foreshore reserve should be big enough to ensure the 27,000 people expected to live in the development in 2120 could enjoy it as much as the initial population.

Acknowledging the economic cost of ceding more foreshore land for developers, the tribunal said there would be economic benefits to having a broad foreshore reserve in terms of residential land values.

Rising sea level predictions will set back foreshore development in Two Rocks. Picture: David Baylis d495054

One of the experts called to give evidence said it was likely the community would find it disturbing to see loss of the foreshore “from 150m down to 50m in the timeframe that someone might own their house”.

Others said a wider reserve should be provided to maintain amenity and protect ecological values of the foreshore, suggesting a seawall would be needed otherwise.

One expert suggested plans should not create “future legacy issues” in greenfield sites for future generations if they could be avoided.

The decision, handed down on August 5 by Judge David Parry, was the first planning case before the tribunal to consider whether the State coastal planning policy required landowners to cede extra land for a foreshore reserve.

The case also raised a novel issue for coastal planning in WA on whether it was appropriate to allow interim use of land that would ultimately have to be given for reserves.

The structure plan envisaged a residential development for about 27,000 people, commercial centres, seven public primary schools and two high schools, as well as regional and public open space.

SAT ruled that approval for the plan would last 15 years.

Coastal erosion has previously caused issues north of Two Rocks Marina, resulting in replacement of beach access stairs.