More than $1.3 billion in federal construction and development projects have been recommended for the Washington area by the National Capital Planning Commission.

Under the commission's proposal, the projects would be built during the next six years. The federal planning agency, in its annual review of long-range building proposals by 16 federal departments and agencies, continues to oppose a dozen federal projects here, including more than $85 million in improvements to National Airport.

The commission has recommended 18 projects that it considers important for the area, but which individual federal agencies and the Carter Administration have not proposed to Congress. Among the 18 are dredging sections of the Potomac River and improvements to the Union Station-National Visitor Center, the National Arboretum and Constitution and Independence avenues.

The planning agency also is urging expansion of Manassas National Battlefield and improvements to six other parks, including the Georgetown waterfront, Daingerfield Island and Jones Point on the Alexandria waterfront and restoration of the decaying 190-year-old markers on the original boundaries of the District of Columbia.

The proposed projects not only would have an economic impact on the area but would result in the transfer of almost 6,000 federal employes, including 2,700 from the Defense Intelligence Agency buildings in Arlington to a new $106 million headquarters at Bolling-Anacostia Air Force Base in the District, and 1,625 Food and Drug Administration employes from District offices to a proposed new $140 million building in Beltsville.

Most of the proposed federal construction in Northern Virginia would be in Fairfax and Loudoun counties, including 17 projects totaling $145 million at Fort Belvoir, $164 million in improvements at Dulles International Airport, about $34 million for improvements at Postal Service buildings and $7 million to resurface the George Washington Memorial Parkway from Mount Vernon to the Beltway.

In Arlington, about $65 million in projects are proposed, including more than $13 million in improvements at Fort Myer and about $20 million in safety improvements to National Airport.

In Alexandria, about $21 million in improvements are proposed for the Army's Cameron Station; in Prince William County about $15.5 million for improvements at the new Veterans Administration National Cemetery at Quantico; $6.4 million for the Quantico Marine base, (most of it for oil-spill prevention); and $770,000 to renovate camp grounds at the Prince William Forest Park.

Not all the 144 construction projects proposed by federal agencies and approved by the commission will be built in the near future, because Congress traditionally funds only 50 to 75 percent of the requested projects. Last year, for example, Congress approved annual funds for 33 of 52 proposed federal projects here; (63 percent). Most of the 19 unfunded projects are included in the planning commission's new 1981-1986 capital improvements program but many may not be funded and could be deferred again.