An optimistic report on the future of business in Washington predicts a more service-oriented economy by 1985 and a relatively tight job market.

The report, prepared by the D.C. Department of Manpower, says that service industries - primarily education, law and medicine - will account for more than a third of the economic expansion in the area during the next decade.

This growth trend is in keeping with what has been forecast for the U.S. economy in general. Greater demand for service jobs is expected to develop as a result of rising personal incomes and technological advances which limit employment growth in the manufacturing sector.

At the same time, D.C. planners predict that government, which has traditionally assured a relatively high income level and economic stability for the Washington area, will grow more slowly, making tourism as the most powerful local business stimulant by 1985.

"The federal government is expected to be less of a stimulus to increased employment in the next decade than in the 1960s," the report states, "as administration of certain social programs is shifted to state and local governments, and as federal policy is directed to limiting the expansion of the federal payroll.

"Washington's continuing development as a center of business activities leisure time are expected to contribute to tourism's strong stimulating influence on the local economy."

In a separate report on the short-run economic outlook for Wahsington, the Manpower Department anticipates moderate growth and a continued vigorous economy thorugh 1978.

It expects the area's growth rate to hold at around 4.4 per cent, the long-term average since 1960. The national average for that period is 3.4 per cent.

Unemployment is expected to slip from 5.2 per cent to 3.6 per cent in metropolitan Washington. For the District itself, it is expected to drop from 9.1 per cent to 6.4 per cent.

"The economic picture in the nation appears to improve, as indicated by strong advances in the gorss national product in the first quarter of 1977," the report says. Reflecting this trend, economic activity in the metropolitan area "is expected to grow moderately and remain strong," the report adds.

Despite the slower growth rate forecast for the government sector - 2.2 per cent annually, compared with 4.2 per cent for service industries - D.C. planners predict that clerical workers will remain the largest occupational category in the metropolitan area, as it has been for several years. Secretaries will comprise 30 per cent of this category, numbering 143,500 by 1985 - the largest single occupation in Washington.

Professional workers (including engineers, journalists and teachers) constitute the second largest occupational category. "Managers, officials and proprietors" represent the third largest.

Employment in the Washington area is expect to grow at 2.4 per cent a year during the 1974-85 period, a rate greater than the 1.8 per cent projected for the nation as a whole. By 1985, planners project that there will be 1.8 million people working in the metro area, an increase of 26.7 per cent over 1974.

When this high employment growth rate is compared to the projected population growth rate - 20.9 per cent for Washington - the implication, D.C. planners note in their report, is that by 1985 the Washington job market will be "relatively tight," meaning there will be a higher ratio of jobs to job seekers than exist today.