Surprising as it may seem to thousands of commuters and tourists, District of Columbia planners think there are far too many all-day parking spaces in downtown Washington and many of them ought to be eliminated.

At the same time, the planners believe strong steps should be taken to preserve existing jobs and to create new jobs in the District - steps that would increase the volume of commuters.

The current and future commuters and tourists should be encouraged and, to some degree, forced to switch to mass transit and such energy-conserving, space-saving transportation modes as "Vanpools" and jitneys, which are sort of a hybrid of buses and taxicabs.

These are only a few of the findings contained in an inch-thick document submitted to the D.C. City Council recently by Mayor Walter E. Washington. The document bears the mind-boggling title, "A draft bill to establish goals and policies for the District of Columbia proposed as the first District element of the comprehensive plan for the national capital."

Ben W. Gilbert, municipal planning director, said the document is a broadbrush preamble and framework - the "first element" - for detailed city planning which, when completed, will cover land use, housing, community development, energy, the environment and the economy.

Under the city's 1975 home rule charter, planning for the future of the District as a municipality - chiefly as the home for more than 700,000 people, as distinct from its role as the nation's capital - was transferred to the mayor's office from the National Capital Planning Commission, a federal agency. NCPC remains as the guardian and overseer of federal interests in the city.

The congressionally enacted city charter directed the District government to prepare a new master plan for city development and to carry it out. The document submitted by the mayor to the Council with a request that it be enacted into law is an early step in carrying out that directive.

Unlike conventional master plans of the past, which stuck pretty closely to physical and geographic planning, the District's new proposal veers heavily toward social planning. It states goals of comprehensive health care, effective education, adequate policing, compassionate welfare and efficient tax collection, among other things.

Each proposed planning policy - stated in formal language that the mayor wants enacted into law - is followed by detailed and potentially controversial commentary that says what the policy means.

For example, take the section on automobile parking.

Here is the legislative language:

"The policies of the District of Columbia to achieve the effective transportation of people shall . . . promote parking facilities that support and complement the community activities of the city with minimum undesirable impacts on adjacent areas."

Here, in abbreviated form, is the commentary:

"Parking problems include an excess of commuter parking spaces in the central (downtown) commercial areas such as Georgetown, Tenley, Friendship Heights and upper Georgia Avenue, and a lack of residential parking in a number of city residential areas.

"The total number of parking spaces downtown increased from 62,000 in 1968 to over 74,000 in 1973. Nearly half of these spaces (37,000) are in commercial and private garages, nearly 12,000 are federal government spaces, about 19,500 are in surface lots and 4,500 are in street parking spaces . . .

"An urgent need exists for overall municipal and federal programs to enhance city policies of support for mass transit, to improve air quality, to balance street vehicular capacity with parking availability, to minimize congestion and to encourage economic vitality.

"A sound parking policy . . . would discourage long-term commuter parking except in conjunction with mass transit in selected locations, discourage present subsidized commuter parking, encourage parking for carpools and vanpools, and permit short-term parking for shopping, commercial deliveries, recreational, cultural and other uses where public transit is not available or is insufficient."

The commentary concludes that all available tools, including zoning and cooperation with suburban jurisdictions, should be used to carry out these policies. Elsewhere in the report is a strong endorsement for completing the entire 100-mile Metrorail system, especially the Greenbelt and Branch Avenue (Suitland) lines.

Following, in brief, are some of the report's other recommendations:

Human Relations - "Diversity among people, occupations, religions, neighborhoods, cultures and entertainments has been, and should remain, a characteristic of the city . . . No neighborhood in the city should be set aside for the exclusive use of any single group . . . "

Land Use - "Uses which mix working places and housing in close proximity . . . will help reduce travel and energy demands."

Jobs - "There is a special need to increase availability of blue-collar and semiskilled jobs . . . (including) for blacks, Hispanics, women and other residents of the District who are under-represented in the local economy."

City Finance - "Closing . . . future budget gaps (between income and outgo) cannot be done with new taxes along. It will require extensive retrenchment and redirection to maintain basic municipal housekeeping and life-support services . . . Many of the programs and projects . . . will be impossible without adequate public revenue resources on which to draw."

Tax Exemptions - "Limitations on federal agencies' purchase of more privately held property than needed should be studied by the federal government. The recent purchase of 32 acres of private land by the (Agriculture of Department's) Arboretum removed this land and its potential development from the city's tax rolls."

Housing - Sufficient units should be set aside for lower- and moderate-income families within diversified neighborhoods.

Commercial Development - "The downtown area, especially the original downtown (between the Capitol and the White House, centering on F Street NW) may need changes in height limits and zoning to encourage a mixture of residential, office, retail and entertainment uses needed to support a vital central area."

Regionalism - The District should participate fully in regional activities and encourage regional taxes for some functions, such as transit. Moreover, "Fairness suggests measures are needed . . . with respect to the taxation of nonresident income earned within the District."

The latter comment supports a so-called "commuter tax," barred by the city charter, but consistently supported by the mayor and other city officials over the objections of suburban congressmen.

The full planning report was published in the Nov. 25 edition of the D.C. Register, which publishes all municipal legal notices. For information on where to see or obtain the Register, telephone 629-4561.