Reports of steady declines in unemployment throughout metropolitan Washington mask a nagging and potentially troublesome problem for many of the area's employers. The number of jobless persons continues to decline, yet thousands of available jobs are going begging as employers seek desperately to fill them.

At 7 percent, the District's unemployment rate is the lowest in six years. The jobless rate for suburban areas, meanwhile, is less than 3 percent. Both figures suggest the existence of a relatively trouble-free economy in which all industry sectors are booming. But the strong employment picture belies a widening problem that has significant implications, especially for some areas of the services, construction and retail sectors.

Employers obviously are concerned that, with fewer applicants for entry-level jobs in those sectors, productivity, service and sales in some cases are declining. And the outlook, for now at least, doesn't appear to be very promising.

Jobs creation is outstripping the area's pool of available workers, the mismatch of jobs and prospective employes still is a serious problem, the entry-level labor force is shrinking, certain types of jobs are being rejected as unsatisfactory employers in some segments of the private sector are doing a lousy job of selling employment opportunities.

There is compelling evidence indicating that all of the foregoing may be responsible for an apparent contradiction in the area's economy.

Not surprisingly for this time of year, some employers attribute the scarcity of workers to a sharp dropoff in the number of students willing to accept traditional entry-level summer jobs. Similar complaints were heard last summer and the summer before that. Then, as now, offers to pay summer employes more than the federal minimum wage have had little effect on the labor shortages.

While it does appear that young people who have grown accustomed to living in affluent surroundings and a robust economy aren't eager to accept traditional entry-level employment, that's only part of the problem faced by employers.

Summer employment was not an issue last year when area government officials and business leaders identified a labor shortage in the suburbs, where job growth has been spectacular over the past two decades.

The issues then were a mismatch of jobs and prospective employes, inaccessibility, inadequate public transportation, unhealthy attitudes among employers and potential employes, and explosive job growth in the suburbs, especially in the services sector. For example, suburban job growth between March 1985 and March 1986 totaled more than 75,000, compared with only 13,800 in the District.

A plan that D.C. Mayor Marion Barry unveiled last year for a cooperative effort among area officials to match unemployed D.C. workers with vacancies in the suburbs only was a start in addressing the problem. A decline in the number of young workers and elitist attitudes among some students notwithstanding, the same issues may require a fresh approach to solving a very real employment problem.

A survey of Washington-area employers last fall contained some findings that probably ought to be considered. The survey showed that employers' overall impression of public employment job applicants is that they lack the necessary skills, the appropriate bearing or the proper attitude to warrant hiring. "The perception that public employment offices provide candidates who are not a good match in this regard indicates an area in need of attention and enhancement," the report said.

A reluctance to apply for certain types of jobs -- even when wages exceed the minimum -- says a good deal more about the labor force in April than it does in August, when more young people supposedly are in the job market. A job that pays $4.50 an hour instead of $3.35 an hour for part-time employment isn't necessarily an attractive choice for someone who either needs a full-time job or for one who has to spend the equivalent of an hour's wages daily for public transportation. It may become necessary, therefore, for operators of fast-food restaurants and some retail firms to restructure their operations as well as upgrade jobs through the use of meaningful incentives.

In the meantime, the steady increase in job vacancies may be the result of market saturation in some cases. Retailers, the fast-food industry and other businesses in the services sector may find it necessary to retrench. In their euphoria over of the strength of the area's economy, they may have misread the dynamics of some submarkets.