Flows from Wyangala Dam, near Cowra, were restricted in October when levels dipped below the critical minimum of five per cent, in effect cutting towns west of Lake Cargelligo off from the river.

But heavy Christmas rains have raised the dam level to about 6.3pc, meaning about 23 gigalitres of water can be sent downstream, the NSW Government decided yesterday.

The Government said the flow would extend downstream past Lake Cargelligo to Lake Brewster by next month and properties further west by early March.

"This release of water will provide an opportunity for landholders in the lower Lachlan, who have not had access to river water for some months, to fill stock and house tanks which should last until winter," said the Water Minister, Phil Costa. "This release will renew the flow of the Lachlan River which has run dry in the lower parts in recent months."

About 600 megalitres of water a day will be released from the dam for a month.

About 100,000 people in the Lachlan Valley are still affected by severe water restrictions, and an emergency plan activated by the Government and water officials last year is still in place despite the temporary reprieve.

Attempts to drill bores will continue at towns including Forbes, Condobolin, Lake Cargelligo, Ivanhoe, Euabalong, Euabalong West, Booligal and Oxley.

Cowra's water supply would be treated with powdered activated carbon to remove potentially toxic impurities, the Government said.

Slashing flows to keep only part of the river flowing had not been tried since Wyangala Dam was built in 1935, State Water officials said.

Water is restricted in many places to ''critical human needs'' levels in some households. This is a daily ration of 150 litres of water a person a day.