With water restrictions in place for more than a week, Maryland Gov. Parris N. Glendening yesterday said that consumption was down 9 percent in the Washington suburbs and 14 percent statewide under new benchmarks intended to measure the drought's effects.

The new statistics show a significantly smaller decline in water use than was reported earlier this week, because state officials have decided to compare this month's consumption with the amount of water used on average over the past five Augusts.

Earlier, the Washington Suburban Sanitary Commission estimated that consumption had declined 18 percent based on a comparison of water use before and after water restrictions went into effect Aug. 4.

Still, Glendening (D) said that he anticipated no change for now in prohibitions on sprinkling lawns or washing cars.

"These restrictions will need to be maintained for the foreseeable future," he said in a statement. "Every long-term prediction shows that this drought is going to continue. By saving as much water as we can now, we are ensuring that we will continue to have this precious resource in the coming months."

Glendening decided to use a five-year average based on advice from statisticians at the Maryland Department of the Environment, said Michael Morrill, the governor's spokesman. Using an average of water use over a period of years is more accurate, smoothing out spikes and declines in consumption over time, he said.

State officials have spent the past week trying to determine the most accurate measurements of the drought to establish a baseline on which to compare conditions in the coming weeks. The monitoring will determine whether water-use restrictions should be eased or tightened.

A drought task force headed by Secretary of the Environment Jane Nishida will report weekly to Glendening on consumption, stream and river flow, rainfall and reservoir capacity.

Stream and river flow is averaging only 30 percent of normal on nine major rivers in Maryland, including the Potomac, according to the statistics Glendening released yesterday. Rainfall is nearly 12 inches below normal statewide. Some of the state's major reservoirs are down to nearly half their capacity.

But those measurements do not include Jennings Randolph Reservoir in Western Maryland, which serves the Washington area. Yesterday, officials released 171 million gallons of water to keep up with the region's needs. The reservoir is 85 percent full, and the region's water supplies are adequate at least through year's end, according to the Interstate Commission on the Potomac River Basin.

Staff writer D'Vera Cohn contributed to this report.