The assessed value of more than half the single-family houses in Arlington remained flat or declined last year, according to county figures released yesterday that are likely to be echoed around the Capital Beltway, spelling trouble for already struggling local government treasuries.

According to notices to be mailed today to more than 53,000 Arlington property owners, the total assessed value of taxable property rose by only 3.5 percent last year, less than a third of 1989's 13.1 percent and the least since 1983.

Arlington is the first locality in Northern Virginia to release assessments and its figures traditionally have been indicative of others. Already, officials in other Virginia suburbs as well as the District are projecting a falloff in assessments because of the slumping real estate market.

The most dramatic decline is being predicted in Loudoun County, where officials are warning of a drop of more than 4 percent. Fairfax officials say their expected drop of 1 to 2 percent would be the sharpest since the Depression.

District officials hope to fare better, and estimate that assessments will level off after several years of double-digit increases.

In Maryland, where local governments revalue property every three years, the slide could be cushioned because the latest crop of assessments include pumped-up values from the end of the bull market. In Montgomery County, for example, values increased by 50 percent since 1987 for houses that were mailed their assessments in December, said Robert Rudnick, the county's state assessor.

Lower assessments -- the latest sign of the death of the past decade's go-go real estate market -- are likely to show up as lower revenue from property taxes, the single largest source of local government money. That is good news for homeowners, but means difficult choices for localities already pinched by cuts in state and federal funding, lower sales-tax receipts because people are buying less, and increased demand for social services from laid-off workers.

"Welcome to the '90s," said Rufus S. Lusk III, president of Rufus S. Lusk & Son, a real estate information firm. "All of a sudden it's come to a screeching halt, and we all have to learn to live with it."

During the last decade of soaring assessments, local officials were able to mask tax increases by cutting tax rates, but raking in more money than the previous year because of rising house values. Now, in a year when most local lawmakers in Northern Virginia are up for reelection, raising property taxes to recoup money lost from shrinking assessments could be risky. Memories of the tax revolt that ousted incumbents in local Maryland elections are still vivid.

"You've got two choices in this world: reduce expenditures or increase revenue," said J. Hamilton Lambert, recently retired Fairfax County executive. "Now the political environment is saying, 'Reduce expenditures.' "

If Arlington's tax rate does not change, the average tax bill on a single-family detached house would rise by a dollar, according to figures released yesterday by County Manager Anton S. Gardner. Gardner said he will not recommend an increase in the tax rate of 76.5 cents per $100 of assessed valuation.

James P. McDonald, Fairfax's deputy county executive for management and budget, told the Board of Supervisors on Monday to expect a 1 to 2 percent drop in property assessments for this year, "which will be the first time since the Depression."

McDonald said assessments on high-rise commercial buildings will drop by 10 percent, reflecting a poor office market. He said assessments on low-rise commercial property will drop by about 5 percent. Final figures will be released in early March, and assessment notices will be mailed after that.

Prince William County officials expect assessments to reflect the pattern in Arlington. Loudoun County officials say their assessment drop is likely to force a tax increase and deep spending cuts. Lambert said those outside-the-Beltway counties could be the worst hit by the assessment slump, due to dramatically lower values on vacant land, "which is what's driving their base."

Saturday, Gardner proposed a $416.4 million budget for the year beginning July 1. It included only a 0.3 percent spending increase, cuts in the county's programs and work force, an employee salary freeze, a new restaurant meal tax and higher fees for other services.

Arlington officials had estimated that real estate tax receipts would rise by 3.3 percent. Yesterday's estimate of a 3.5 percent increase means a few hundred thousand dollars more than expected.

"Even that little bit will significantly help us," said County Board Chairman William T. Newman Jr. Staff writers Michael Abramowitz, Steve Bates, Stephanie Griffith, Thomas Heath and Brooke A. Masters contributed to this report.