Under the plan to raise the dam wall, up to 1000 hectares of world heritage area and 3700 of surrounding national park will be inundated for up to two weeks.

The World Heritage Centre in January asked the Commonwealth to provide an update on the state of conservation of the Blue Mountains heritage area after more than 80 per cent was ravaged by fire last summer.

In its response, the Commonwealth said the NSW government department in charge of raising the dam wall - Water NSW - will re-assess the impacts to the project area and include them in the environmental impact statement later in the year.

"As part of the EIS process, the NSW government will require Water NSW to undertake an evaluation of the recent bushfire impacts," the Commonwealth's state of conservation report said.

The draft EIS, seen by AAP, states Water NSW has no intention to re-assess the area impacted by fire.

"It is reasonable to conclude that further assessment in line with the guidelines is not required for this assessment," the document says.

This is despite 58 threatened species within the area considered to have been disproportionately impacted by the bushfires.

These include the koala, critically-endangered regent honeyeater, greater glider, broad-headed snake, brushtail rock wallaby, eucalyptus benthamii and eucalyptus glaucina.

Ornithologist Martin Schulz said last summer's Green Wattle Creek blaze burnt most of the southern Blue Mountains leaving only a small unburnt section which will likely be flooded.

"The ecosystems are different and parts will be in recovery for decades. How can an assessment done before the fires be valid? The fires changed so many things," he told AAP.

The draft EIS shows before the bushfires only 15 hours of spotlight searches were conducted for the koala, greater glider and squirrel glider in the inundation area, despite a recommendation of 61 hours.

Dr Schulz says this is "bafflingly low" especially for koalas.

The time spent gathering sample collections of the squirrel glider and brush-tailed phascogale also did not meet the guidelines with only 1820 nights completed but 3224 nights recommended.

The assessment of the large-eared pied bat was 11 times less the suggested amount with traps laid for 78 nights yet 864 recommended.

"The low survey effort for the large-eared pied bat is particularly disappointing," Dr Schulz said.

"It may not be glamorous like the koala but I don't think anyone wants to push a species to the brink for a dam."

Community group Give a Dam spokesman Harry Burkitt called on the federal government to intervene.

"The barrow-loads of leaked material now in the public domain show (Western Sydney) Minister Stuart Ayres and Infrastructure NSW haven't even bothered following NSW guidelines, let alone those required under federal law or by UNESCO," he told AAP.

Infrastructure NSW, which oversees the project, says feedback from state and federal governments on the draft EIS is important in developing the final version.

"The final decision on the dam raising proposal will only be made after all environmental, cultural, financial and planning assessments are complete," a spokeswoman told AAP.

A spokesman for federal Environment Minister Sussan Ley told AAP the minister might request further information from Water NSW if matters of national environmental significance have not been fully assessed.

The World Heritage Committee, which selects sites for UNESCO's world heritage list, has expressed concerns over the project and will review the EIS before the federal government's decision.

Australian Associated Press