Sussex could be gripped by drought after one of the driest winters for 130 years, experts have forecast.

Depite yesterday's heavy snowfall, the large underground water reserves, which provide much of the supply in the summer, are at levels well below average, raising the prospect of an "environmental drought" in which river levels will have to be reduced to supply people at the expense of wildlife.

The three-month period from November 2004 to January 2005 was the fourth driest winter period in the South East since records began in 1883.

Environment Agency spokeswoman Catherine Henwood said there was still time for water levels to recharge and it was unlikely standpipes would be brought into use.

But she added: "It is a case of waiting to see. The message we are trying to get out is that there are things people can do in their homes to conserve water."

Last month experts said unless Sussex experienced heavy rain before the end of March there was likely to be a drought later in the year.

The snow that has fallen in the last couple of weeks has done little to help because 30cm (1ft) of snow is only equivalent to 3cm (1in) of water. Reservoir levels are also below average. Weirwood reservoir, near East Grinstead, is only 56 per cent full, compared with its usual 95 per cent.

According to the Environment Agency, only half the normal amount of rainfall was recorded in the South between November and January.

There is usually an average of 81mm of rain across the region in January but this year there was only 39mm.

Last month the situation was even worse, with between 20 and 45 per cent of the usual amount of rain. Peter Midgely, regional strategy manager for the Environment Agency, said: "We simply need more water to fall from the sky.

"Water is a very precious resource and we could all do more to make sure we don't waste it. Thousands of litres are wasted every day by dripping taps and people using hosepipes.

"Using a bucket when washing the car or a watering can for the garden is much more water-efficient than a greedy hose.

"Just switching off the tap when you are brushing your teeth can save a vast amount of water during a year."

Meyrick Gough, Southern Water's water planning and strategy manager said: "Underground water sources rely solely on winter rainfall to fill them up. About 70 per cent of water supplies in the Southern Water area come from under the ground so it is vital these sources benefit from rainfall before the spring and summer.

"The recent weather, along with predictions from experts that climate change will cause summers to be longer and hotter, shows how important it is that we use water wisely. We can all be more aware of the amount of water we use and take steps to conserve it where possible."

South East Water, which supplies tap water to people in the far east of Sussex, said its Arlington reservoir was full but Ardingly reservoir was below average.

James Grinnell, water resources manager, said: "Prolonged spells of rain are now needed in the next few weeks to help replenish our groundwater, river and reservoir levels."