Bourke, Brewarrina and Walgett shires in flood-hit north western NSW have been announced natural disaster regions.

Sluggish moving flood waters from Queensland have now cut off a number of communities in the area, with some townships expected to be isolated for up to six weeks.

Emergency Services Minister Steve Whan, said that the townships of Goodooga and Wanaaring are now isolated.

In the meantime, evacuation orders are in position for the nearby Weilmoringle and Goodooga native reserves.

Mr. Whan said the full degree of the damage in the Bourke, Brewarrina and Walgett shires would not be known until flood waters retreated in upcoming weeks.

On Monday, Mr. Whan said, "Coming so soon after major flooding at Christmas, these floods are causing and compounding significant damage to roads and other public infrastructure across the Bourke, Brewarrina and Walgett shires".

He said that this natural calamity announcement means that a variety of people who have experienced property damage from these floods, including inhabitants, farmers, business owners and councils, can ask for aid.

Mr. Whan also said that the State Emergency Service (SES) had 13 aircraft flying carrying out resupply operations to isolated towns and properties.

He added that the emergency services, together with other necessary services, have done a brilliant job of helping these communities and are now assisting to control the threat caused by these latest floods.