NSW Environment Minister Gabrielle Upton was warned by her own department that an easing of land-clearing codes could trigger a 45 per cent jump in the rate of native vegetation destruction on farms.

Advice by the Office of Environment & Heritage (OEH) dated August 25, 2017 – just as the minister was signing off on an overhaul of the state’s biodiversity laws – reveals how much extra clearing Ms Upton’s department expected.

Land-clearing rates for agricultural use had been running at about 9000 hectares a year, a rate likely to surge to about 15,000 hectares annually over the period 2017-18 to 2019-20, according to the document obtained by the NSW Nature Conservation Council under freedom of information laws.

“The regulatory changes in the [Land Management Code] may further increase agricultural clearing in NSW by between 8 per cent and 45 per cent annually,” the document said. “There may also be a spike in clearing in the first two years of the code due to landholders’ behavioural responses to regulatory change.”

The risks include undermining “the viability of certain threatened species”, with the dangers highest in the over-cleared landscapes of the Northern Tablelands, the north-west, central west and western NSW.