WITH A BUILD-AWAY majority now in command on the Loudoun County Board of Supervisors, developers are having a field day. Loudoun is the fastest-growing county in the country, and the supervisors are gleefully seeing to it that this dubious distinction not be lost. With maximum speed and minimum public notice, the new majority is reversing planning measures put in place by the previous board. The full effects of its actions won't be felt for perhaps 10 to 15 years, and then there will be little turning back. In the first three months of this year alone, the board approved 3,000 residential units through rezonings, with little regard for the impact on taxpayers.

To grease the skids for the builders, the board majority has ignored established rates that developers should pay to help cover certain services such as schools, roads, public safety and recreation. In some instances the board has accepted payments amounting to little more than half of the cost of the estimated impact on facilities, which leaves the remaining costs to be borne by taxpayers. The supervisors also ignore their county planners' concerns about opening up large areas to public utilities without sufficient data about traffic, pollution and other consequences. They are talking about adding tens of thousands of additional homes to county plans. Already, Loudoun officials plan to open 20 schools in the next five years to accommodate additional students in a system that hires new teachers by the hundreds every year. How many more schools will be needed to keep up with the latest moves?

Some officials in Stafford County, Virginia's next-fastest-growing county, hope that the renewed supervisor zeal for feverish development in Loudoun will take some of the development attention away from Stafford. As reported by The Post's Michelle Boorstein shortly after the new Loudoun board majority went to work, Stafford officials say they are under mounting political pressure to push for more local and state controls on growth. Loudoun residents who understand the damage that their leaders are to doing to the county should make their feelings known to their state legislators. Growth can't be stopped, but reckless ruination can and should be.