After a week of voluntarily conserving water, Northern Virginians are consuming close to their normal amount, even though the level in their major reservoir continues to go down.

Consumption, which had fallen as low as 55 million gallons daily, rose to 59.5 million gallons Sunday. Normal usage before the water emergency that began 2 1/2 weeks ago was 60 to 65 million gallons daily.

Northern Virginia officials have warned that if voluntary conservation is not effective, they will have to impose mandatory restrictions that could lead to the closing of business.

The center of concern is the Occoquan Reservoir, which the Fairfax County Water Authority depends on to serve most of its 612,000 customers in Alexandria and Fairfax and Prince William counties. Since early May, the reservoir gradually has been shrinking because of lack of rainfall.

The reservoir dropped 4 inches to 104 feet, 8 inches yesterday - another record low - as voluntary conservation efforts waned. The brief rainfall Sunday sent little runoff into the tributaries that feed the Occoquan.

While the reservoir continued to recede, water authority officials continued their negotiations with Manassas in an effort to buy 1.5 billion gallons of water from the city's Lake Manassas reservoir.

While the 5-billion-gallon lake is half the size of the Occoquan and serves only 1.30th of the customers, water authority officials do not look at it as a long-term solution to their needs. Unlike the Occoquan, Lake Manassas has a small watershed (Broad Run) from which to collect water, and consequently does not fill up as fast.