NSW Department of Water and Energy deputy director-general, David Harriss, says that as the drought continues, river levels will remain at record lows and a number of the valleys' creeks and streams will become disconnected.

"The Department understands that this will have a significant impact on some landholders and is providing them information on which systems are likely to be affected and what alternative water supplies are available," Mr Harriss said.

Mr Harriss explained that significant amounts of water is lost through evaporation and seepage when transporting water along creeks and streams that branch off the main river channels.

"Disconnecting some creeks and streams is one way of conserving more water for critical human needs during the current extreme drought and to provide water for industry to maintain the communities that depend on these," Mr Harriss said.

The following creeks and streams have already become disconnected:

• Colligen/Neimer system

• Yallakool/Wakool River

• Bullatale Creek

• Merran/Cabool/Waddy/Little Barbers

• Old Man and Beavers creeks

• Lowbidgee irrigation district

• Flood runners and effluents off the Yanco/Colombo/Billabong Creek system

• Nimbo creek

• Holts Anabranch

• Euston Lakes

In addition it is likely that the Edward/Gulpa system and will continue at very low flow levels, in the short term.

"The Department is urging stock and domestic users on these systems to look for alternative supplies," Mr Harriss said.

"Unless we receive significant inflows in the Murray and Murrumbidgee (including the Tumut River) river systems, flows into these creek systems cannot be guaranteed in the coming year."

Mr Harriss said that the Department had made limited water releases into some disconnected systems in the past year and will continue to do so as a priority if and when water availability improves.