The backlog peaked at 320 nominated places or objects in 2008 that had not been assessed and has been reduced, but still stands at about 136 nominations at the end of June last year - the latest figures the territory government would provide.

But the delays the backlog is causing has prompted calls from the Kingston and Barton Residents Group, among others, for the government to update heritage listings for several landmarks across the inner south to include the social contribution of the buildings.

Among them, the group has urged the listings for Telopea Park, Manuka Pool, Manuka Oval precinct, the Forrest Fire Station and the Kingston shops be updated.

KBRG president Rebecca Scouller said there was no "conservation management plan" for Telopea Park or Manuka Pool, while a draft conservation management plan (CMP) for Manuka Oval precinct "had been stagnant for some time”.

She said a further nomination lodged as long as 15 years ago for the Kingston Shops had still not been officially assessed.

While a spokesman for the Environment and Planning directorate said a CMP was being developed for "Manuka Circle Precinct", which included the oval, pool and Manuka Arts Centre, he would not say when it was expected to be completed.

"The current priority for the ACT Heritage Council is assessing the existing backlog of nominations to the ACT Heritage Register to provide certainty to the heritage status of nominated places and objects, however the council amended the registration details for one place in 2016," he said.

"The council and ACT government have invested considerable resources in addressing the backlog of nominated places and objects."

National Trust ACT heritage committee member Eric Martin said delays were common in both official heritage assessments and conservation management plans.

He said there were a raft of problems with the territory's heritage system leaving both property owners and the public in the dark.