NO WONDER SO MANY preachments on conservation of our natural resources seem to falling on deaf ears. Not only is austerity still an alien value, but the rewards for self-restraint may turn out to be stiff penalties. Only yesterday, for example, residents of suburban Maryland got an expensive thank-you for having used less water than expected: their rates were raised -- suprise -- to offset lagging water sales.

The Washington Suburban Sanitary Commission, provider of water and sewer services for Prince George's and Montgomery counties -- figured out that if customers continue their prudent ways, the agency could lose perhaps $6 million a year, or about $5 a year for each of its 1.2 million users. The commission won't give its customers even verbal credit for frugality; instead, an agency spokesman claims that the drop in consumption is "obviously weather-related; it doesn't have anything to do with customer conservation."

The WSSC logic goes this way: there has been so much water from the skies this spring, summer and fall that it has reduced the amount needed and sold for outdoor uses; and that leaves the agency with lower revenues. To recover the loss and cover the agency's expenses, up go the water bills. On paper, of course, this looks reasonable enough. But like the end of odd-even gasoline sales or the ways in which other utility rates have favored heavy users with volume discounts, the WSSC's move is another unfortunate message to consumers always eager to hear that shortages don't exist or that a crisis is over.

It is all the more unfortunate in this instance, since the WSSC has just been featured in an industry publication as having run a successful conservation campaign, written up by two of the agency's officials as "sincere, innovative and absolutely relentless." It is true that the agency has worked hard to encourage conservation and does have a policy or lower rates for small-volume users. But blaming the angry gods for bountiful water supplies and then socking it to customers who have used fewer gallons amounts to throwing out the policy with the bath water.