The Washington area's elderly population is expected to increase 53 percent by the year 2010, outstripping the projected national increase of 37 percent, the Metropolitan Washington Council of Governments said yesterday.

Don Wassmann, chairman of the COG Committee on Aging, said the growth in the number of Washington area residents aged 65 and above is partly due to greater employment opportunities here for older workers.

Other factors, officials said, include improved health care for the elderly, the maturing of the baby-boom generation and the large number of military personnel who come to Washington on assignment and remain after they retire.

COG estimated that the Washington area had 269,000 residents aged 65 and above in 1985, 7.9 percent of the total population of 3.4 million. The senior population here probably will total 412,000 by the year 2010, about 9.2 percent of the projected population of 4.5 million, officials said.

An area breakdown by jurisdiction of the forecast is being developed and probably will be announced in February, COG officials said.

The elderly population represents one of the fastest growing segments of the population here and nationwide. To help area residents find services for the elderly, COG has developed a brochure, "Resources for the Aging and Their Families," for distribution through senior centers, libraries and Peoples drugstores, officials said.

Among other things, the brochure lists the phone numbers for 10 Area Agencies on Aging. The agencies, which are financed in part by the U.S. Older Americans Act, provide "one-stop information on housing, retirement planning, and other community services," the brochure says.