AUTHORITIES have advised people to leave the Rocklands Reservoir area as the Grampians fire continues to rage out of control.
Lightning sparked the bushfire in the southern Grampians a week ago.
It had grown to about 26,000 hectares by 6pm yesterday.
The blaze grew by about 11,000 hectares since Wednesday alone and is forecast to get bigger.
All areas of the Victoria Valley and Victoria Range are closed.
The Henty Highway remains closed between Mooralla and Cherrypool, with diversions at Horsham and Cavendish.
Grampians Tourism Road is open between Dunkeld and Halls Gap.
About 350 Department of Sustainability and Environment, Parks Victoria and Country Fire Authority fire-fighters battled the blaze yesterday.
They were supported by about 100 night shift fire-fighters, about 40 fire-fighters from New South Wales and New Zealand, 13 aircraft and 20 bulldozers or graders.
Department of Sustainability and Environment incident controller Russell Manning of the said there were several breakaway fires across the Henty Highway yesterday afternoon.
Authorities issued an emergency warning for Glenisla at 3pm yesterday.
"We have contacted all the people on Hynes Road, which is in the line of impact," Mr Manning said.
"Fire-fighting crews have cut fire breaks around properties.
"We are still trying to round up the major run of fire, which ran into the dry bed of Rocklands Reservoir.
"The fire is not affecting infrastructure at this stage.
"It is still contained within the Grampians and Woohlpooer State Forest.
"The fire has burnt four kilometres west of the Henty Highway. It has not burnt houses or sheds, so there is no asset loss there at the moment."
Mr Manning thanked fire-fighters for their great efforts in keeping asset losses to a minimum.
About 60 sheep, 1500 hectares of grassland and pasture, two sheds and about 15 kilometres of fencing were lost to the fire in the Victoria Valley earlier this week.
GWMWater spokesman Andrew Rose said the fire had not affected water storages.
Rocklands Reservoir is 36 per cent full.
Moora Moora Reservoir is also in the fire's vicinity.
Mr Rose said there had been no impact on GWMWater infrastructure.
"We have had no problems with ash and will continue to monitor the situation," he said.
"Rocklands is generally used by GWMWater for consumption. It's a back-up supply for the Wimmera-Mallee Pipeline. One of its primary functions is for environmental flows for the Glenelg River."
Mr Rose said GWMWater sold wholesale water from Rocklands to Wannon Water, which supplied towns including Balmoral. Hamilton also had access to Rocklands water but was not using it at present.