The proposed Great Koala National Park aims to link dozens of koala hubs near Coffs Harbour to protect 100 native species, including up to one in every eight koalas living in NSW, Queensland and the ACT.
While a footprint twice the size of Canberra capturing several state forests is under consideration, loggers say something one-fifth the size will protect thousands of koalas as well as jobs and critical wood supply.
Spatial mapping, seen by AAP, has for the first time revealed almost 100,000 hectares of native forest will remain open to harvest if industry's preferred option of a 37,000-hectare park is adopted.
The satellite imagery analysis, provided by the Australian Climate and Biodiversity Foundation, accounts for creeks, rivers, cliffs and similar terrain that cannot be logged.
Former treasury secretary turned climate warrior Ken Henry said the maps showed that the "dramatically smaller protected area" put forward by industry also "significantly overstate(d) the scale of actual forest protection" by including areas of forest already excluded from logging.
The "preferred" option only involved the industry relinquishing 20,000 hectares of previously available forest, he said.
"The forest areas being assessed for the Great Koala National Park are worth far more to regional communities if they are preserved to store carbon, which will fund more jobs to manage our forests, provide a safe habitat for koalas, and make the bush more resilient to hazards like fires," the foundation chairman said in a statement.
The criticism came a day after stalwart environmentalist Bob Brown said 79 per cent of Labor voters and 62 per cent of coalition voters backed an end to native forest logging.
The koala park and recent financial troubles have spotlighted NSW's native forest industry amid the forced closure of its counterparts in Victoria and Western Australia.
But the industry, in dismissing the spatial mapping figures, said allowing a koala park twice the size of Canberra would drastically affect thousands of jobs and local supplies of flooring, decking and power poles.
"Over 70 per cent of Australia's power poles come from the mid-north coast (of NSW)," Australian Forest Products Association NSW chief executive James Jooste told AAP.
Uncertainty about the park's boundaries was weighing heavily on "hard-working, skilled timber workers" and their families, he added.
Environmental groups' and industry's cost estimates to establish the park vary wildly between roughly $150 million to $1.3 billion.
The government says its assessment covering environmental, economic, social, ecological and cultural issues is ongoing.
Environment Minister Penny Sharpe has previously described the park as NSW Labor's "biggest environmental commitment" but has declined to say precisely when before the 2027 election it will be delivered.
