Residents are being urged to cut down on their water use now the reservoir in Great Harwood is already 20 per cent down on capacity.
Dean Clough reservoir was measured as being 81.5 per cent full with water by United Utilities this week..
Overall stoick of water in north west reservoirs is 64.2 per cent. Neighbouring Rossendale lakes - Cowpe, Clowbridge, Calf Head (Grane) and Clough Bottom - are all only half filled or less, the utility company confirmed.
A spokeswoman for United Utilities said: "It certainly is a healthy level of water in Dean Clough compared to some reservoirs. We have been manipulating waters around the system which has helped."
It provides water for areas of Hyndburn and is part of a reservoir system that serves areas of the borough.
Although a hosepipe ban has not yet been issued the utility company has called on people across Hyndburn to use water "wisely" amid the driest start to the year in the north west since 1929.
Polly Rourke, of United Utilities, said: "We would normally expect reservoir levels in the Pennine area to be about 75 per cent full at the beginning of July. The four Rossendale reservoirs are currently 40 to 50 per cent full. That gives you an idea of how dry it has been."
She added: "Even though it has rained a little this week we’d expect to need about four inches of rain before the water started running from the land and into the reservoirs. We are still asking people to use water wisely. We haven’t issued a hosepipe ban but with every passing day we are assessing the situation."
Rainfall in May was just 38 per cent of the region’s long term average.
In 1976 prolonged periods of low rainfall followed by 14 days of hot weather caused a drought in Britain. So far the conditions this year do not match those of 1976.
To prevent water shortages this summer United Utilities have urged people to turn off the tap when you brush your teeth, use the washing machine or dishwasher with a full load, fix dripping taps, fit a save-a-flush in the loo to save one litre of water every time you flush, use a watering can instead of a hosepipe or sprinkler and to take showers opposed to taking a bath.
Polly added: "It has been an exceptionally dry spell. Because our system is one big integrated system of pipes we can move water around to compensate."
Bill Darbyshire, Drought Manager for the Environment Agency said: "We are working closely with United Utilities to make sure they are doing everything they can to secure water supplies, manage customer demand and tackle leakage. Drought has serious consequences for wildlife due to the low river flows. The situation is a reminder that water is a precious resource which we must all use more wisely."
A spokesman for the Met Office said: "Generally as we go into the weekend and next week the weather will be a bit more unsettled in Lancashire. We have of course had some decent summer weather of late but it will be a bit more mixed in July."