Unemployment in the District of Columbia rose substantially from May to June. The increase resulted primarily from the addition of students on summer vacation to the work force, city officials said yesterday.

Figures released by the D.C. Department of Employment Services showed that unemployment in the District for June was 7 percent, compared with 6.2 percent in May. But the 7 percent figure was lower than the 8.2 percent unemployment suffered by Washington residents in June, 1979.

Unemployment in the metropolitan area as a whole also increased, from 3.9 percent in May to 4.7 percent in June. In June, 1979, unemployment for the metropolitan areas stood at 4.9 percent.

In a related announcement, the department said yesterday that registration now is open for an additional 1,300 jobs under the city's troubled summer employment program for youth.

The jobs, to be filled on a first-come, first-served basis by low-income youths from 16 to 21 years old, were made possible by a supplemental federal grant under the Comprehensive Employment and Training Act. The jobs program has been plagued by bureaucratic foulups and extensive delays in processing paychecks for the youths.

The summary of employment figures showed that the number of jobs in the District increased by 2,600, from 619,500 in May to 622,100 in June. The largest component of the increase was 1,700 new federal government jobs, the department said.

However, the number of persons seeking work increased by 2,900 -- most of them students looking for summer jobs, according to the department.

The city also released a 1979 federal survey of wages in the building trades in the District. The figures show that as of last year, journeyman workers in plumbing-related trades made the highest wages, with sprinkler fitters in that group, earning the top wage of $13.13 an hour.

Most journeymen in the building trades earned more than $11 an hour. Workers in highway and street construction however, earned between $7 and $8 an hour.