The Canberra Liberals' future population estimate for Kowen is twice as big as a high density estimate developed 16 years ago, and appears based on the reported recollections of a former National Capital Development Commission head.
Opposition Leader Elizabeth Lee last month said the NCDC had said the area - on the eastern edge of the ACT - had space for 200,000 people.
But The Canberra Times has not been able to find any record of the claim made by the commission and the Liberals did not provide a source when asked. The figure was attributed to the recollections of a former commission head in a 2019 City News column.
The Canberra Liberals last month announced they wanted to build housing and a new town centre at Kowen Forest, a commercial pine plantation.
The party's policy document said the Kowen development would accommodate over 100,000 new dwellings and support a population of up to 200,000 people.
"By providing various housing options, Kowen will allow increased choice for Canberrans and cater for the diverse needs of a growing community," the Liberal policy said.
The ACT government has previously calculated Kowen's developable area at 30 square kilometres, meaning a population of 200,000 people would result in 6,666 people a square kilometre, a density higher than Hong Kong and Tokyo.
Opposition Leader Elizabeth Lee cited the National Capital Development Commission, the pre-self government agency responsible for the development of Canberra, as the source of the claim Kowen could accommodate a population of 200,000 people.
"It was the NCDC at the time who actually said in fact that area has the capacity to fit 200,000 population," Ms Lee told ABC radio on September 19.
The Canberra Times has been unable to locate any primary source produced by the National Capital Development Commission with that population figure for a future Kowen development.
A Canberra Liberals spokesman on Friday did not provide a source for the NCDC's figure when asked.
"A Canberra Liberals government will deliver 125,000 new dwellings by 2050 which includes 100,000 new dwellings in Kowen," the spokesman said.
"The Canberra Liberals have had a number of conversations with planning experts who have confirmed this is more than achievable with a mix of housing types."
A secret NCDC working paper, revealed by The Canberra Times in February 1977, projected a possible population of Kowen at 97,600 residents under a "compact development" plan for the ACT to the year 2021.
The 2004 Canberra Spatial Plan said the Kowen plateau had a total capacity for 26,000 dwellings. The average number of people per dwelling in the ACT in 2021 was 2.5, giving a population of 65,000 people.
The ACT Planning and Land Authority in 2008 told SMEC, a consulting firm, it had completed a "desk top" assessment and found Kowen may have urban capability of around 3000 hectares, equivalent to 30 square kilometres.
The authority told the consultants it had three population scenarios for Kowen. A low development scenario with 33,000 dwellings and a population of 78,300 people; a medium scenario of 39,000 dwellings and 84,600 people; and a high scenario of 46,500 dwellings and a total population of 100,350.
SMEC used the information as part of a 2008 report on traffic and transport modelling for the Eastern broadacre areas of the ACT.
The only reference to a population of 200,000 people at Kowen located by The Canberra Times is contained in a 2019 City News article written by former Labor chief minister Jon Stanhope.
Mr Stanhope indirectly cited personal correspondence and discussions with Tony Powell, the former commissioner of the NCDC, about Canberra's future land and infrastructure needs. Mr Powell died in 2021.
"Pertinently, Mr Powell advised me that in early planning work by the NCDC for the city it had assumed a population of 200,000 for the Kowen area," Mr Stanhope wrote.
Mr Stanhope added: "Mr Powell also commented that because of recent planning changes to the ratio of detached to unattached housing and the move to multi-storey apartment blocks that the Kowen Plateau might possibly be expected, in the future, to house up to 300,000 people."
