Deposits of commercial banks in the District of Columbia rose 11 1/2 percent in the past year and now exceed $5 billion for the first time in history, according to a Washington Post survey yesterday.

The city's 17 banks, including newcomer Women's National, reported total deposits of $5.13 billion on June 30 compared with $4.59 billion one year earlier and $4.96 billion on March 31, the previous record.

Although the expansion of city bank deposits indicates continued growth of the local industry and area business generally, the rate of deposit growth has slowed somewhat from a 15 percent gain in the first quarter this year and 14 percent at this time last year. If the growth rate continues to decline, it could indicate the start of a regional slowdown after two years of vigorous expansion.

Women's National, the nation's first federally chartered bank owned and managed primarily by women, opened six weeks ago and already had deposits of $2.3 million by June 30. Assets exceeded $4 million, President Emily Womach said yesterday.

Riggs National, the largest in D.C. continued to demonstrate significant deposit growth - up more than $200 million in the past 12 months to $1.84 billion. Deposits also were up sharply at the city's two black-owned institutions, Industrial and United National. Detailed figures for the 17 banks follow: