The White population of Washington increased in 1976 for the first time in a quarter of a century, according to District of Columbia government estimates.

The D.C. municipal planning office, in a recently released study estimates that the white population in predominantly black Washington increased last year by about 6,400 from 162,700 in mid-1975 to 169,100 in mid-1976 - the first such numerical increase since 1951.

Meanwhile, the black population continued to declined - a trend that started in 1973 - and now stands at about 538,800, according to the city's estimates.

Planners and statisticians, both government and private, said yesterday the new figures reflect the surge in recent years of white housing redevelopment in such diverse parts of the inner city as Adams-Morgan, Logan Circle, Capitol Hill and Shaw.

Young white singles and childless couples have been moving into these formerly black neighborhoods, buying restored row houses, condominium apartments or new dwellings constructed on vacant pieces of property.

The figures are likely to add to concern among some black leaders, who feel the white return to the city is having a disruptive effect on poor blacks ousted by redevelopment.

Some blacks including former D.C. School Supt. Barbara Sizemore and recently deceased City Councilman Julius Hobson Sr., have contended the white return is part of a deliberate scheme by white interests to dilute the city's black power base by scattering inner city residents to the suburbs.

District of Columbia government planning officials stressed yesterday that the 1976 population estimates are "provisional" and "preliminary" and should not be viewed by themselves as confirming a trend.

"It's a small increase," said municipal planning director Ben Gilbert ". . .but I don't think it's prophetic of a great big turnaround."

He said he does not expect the city to become significantly whiter, but we'll probably continue to have some return of young whites who like city living . . .I don't share the fear of wholesale disruption and destruction of living patterns."

On the contrary, Gilbert said, "This is a sign that the city is healthy, that it's not being abandoned."

The 1976 estimates show that the city's white population grew in almost all age categories, especially the 25-to-39-year-old bracket, while the black or "non-white" population declined in all age groups except 20-to-24 and 55-to-64.

The increase of more than 6,000 whites in the 25- to 39-year-old bracket from 1975 to 1976, Gilbert said, indicates an influx of singles or childess couples many from outside the metropolitan area.

Until 1976, the influx of relatively young whites had been offset by the continuing outmigration of older white families from what were traditional white sections of the city, such as Michigan Park in northeast. Brightwood and Petworth, off upper 16th Street NW.

The older families now have virtually disappeared, and the neigborhoods have stabilized as predominantly black but with some new white families beginning to arrive.

With the advent of open housing and the availability of moderate-cost homes in nearby Maryland and Virginia, blacks also began an exodus to the suburbs in recent years. The historic influx of rural blacks to Washington from the South came to a virtual halt at the same time, thus causing the current decline in black population in the city.

Many of the outmigrating blacks appear to have settled in close in suburbs of Prince George's County adjacent to Washington's heavily black far northeast and far southeast sections.

From the turn of the 20th century to the end of World War II, Washington's white population held steadily at 70 per cent to 75 per cent of the total.

With the development of the suburbs after the war, the white population of the city began to decline, picking up speed as incoming blacks from the South replaced whites in formerly all-white neighborhoods.

In 1957, according to D.C. municipal planning office figures, the city for the first time became more than 50 per cent black. The percentage increased rapidly thereafter, reaching a high of 77.5 per cent in 1975, according to the estimates.

In 1976, with the new increase of whites and the continuing decline in blacks, the proportion of whites rose slightly from 22.5 per cent to 23.9 per cent, the first increase in the white percentage since 1943, the statistics show.

The population of the city as a whole has declined steadily since World War II. Demographers say this is typical of many large eastern cities and attribute it to suburban residential development and the decline of business and industrial activity in urban centers.

Washington's population in mid-1976 was estimated at 707,900 by the minicipal planning office, down from 756,510 in 1970.

The S. Census Bureau, which makes its own estimates between the formal headcounts at the beginning of each decade, estimated Washington's 1976 population at 702,000.

D.C. municipal planning office statisticians say they use a combination of birth, death, school enrollment and migration data to make their estimates.

A private demographic consultant with extensive experience in Washington area population studies said the municipal planning office methodology was "sound" and developed by a "competent and professional staff."