The cost of Blowering Dam's foreshore works has hit $1.3 million with the recovery project still ongoing.
Access to the state forest on the western foreshore will remain closed over the Christmas period, as dead trees continue to fall and the roads are severely damaged from the devastating summer bushfires.
Yellowin Access Road, McDonalds Trail, Sturgess Trail, Foreshore Road (from Jounama Dam to Snubba Road) and Blowering Camp Road will all be closed.
Rain and road damage have severely limited Forestry Corporation of NSW's ability to undertake remediation around the Blowering Dam.
Work is set to continue well into 2021, said the Snowy Region manager, Dean Anderson.
"The scale of infrastructure damage is simply unprecedented; we have not been able to access some roads ourselves due to hazardous conditions," he said.
"All up, there are over 170 kilometres of damaged roads needing repair just in the State forest next to Blowering Dam, this is longer than the road trip from Tumut to Gunning.
"It is also worth noting that in the 1960s when the then Forestry Commission of NSW was asked to establish pine plantations to help protect the Blowering catchment, there were over 60 dams built to reduce silt and soil entering the dam.
"During the Black Summer fires these dams have done the job they were designed to do and captured a lot of the silt coming off the now bare hills."
Engineers and soil specialists have been engaged to assess what should be done with each individual dam. One dam has been emptied using a local contractor as a way of evaluating what options are available.