By law, under the 2,100-page congressionally approved omnibus spending bill for 1988, the Small Business Administration must return to Clarksburg and Charleston, W.Va., two employees -- a manager and a specialist -- detailed last August to cities outside that state.

The same law requires the National Oceanic and Atmospheric Administration to maintain three people at the National Data Buoy Center in Bay St. Louis, Miss., to work on contracts and procurement "in the same manner and extent" they did previously. "Where practical," this provision of the law goes on, "these positions shall be filled by the employees who performed such functions prior to June 26, 1983."

The Air Force, by the same law, must spend $22 million of its operation and maintenance money "only to operate a C130E {aircraft transportation} unit at McChord Air Force Base, Washington."

The Reagan White House, which regularly complains about congressional efforts to direct or influence foreign policy, hardly ever focuses attention on this type of domestic agency micromanagement. Tonight, however, may be different.

President Reagan, in his State of the Union address, is expected to refer to the catchall fiscal 1988 spending bill he signed Dec. 22 to stimulate public support for his "line-item veto" proposal. Such legislation would give him the right to go into each congressionally passed measure to eliminate specific pieces that he dislikes. Under current law, he must veto an entire bill if he opposes only a small portion of its contents.

The examples Reagan is expected to cite tonight -- money that legislators inserted for ridiculous-sounding studies -- should easily draw public contempt. But old-fashioned "pork-barreling," even in modern dress, often allows lawmakers to force federal agencies to accomplish what they want for their constituents back home or to help achieve political purposes.

As a result, Congress has regularly voted down a "line-item veto" and probably will continue to do so.

Beyond easily criticized studies on raising redfish or of declining asparagus yields, the spending bill contains items that bear the imprint of top congressional leaders.

Senate Majority Leader Robert C. Byrd (D-W.Va.) was the author of the language that ordered the SBA to hold employment levels at the West Virginia offices "at the same levels that were in place as of August 30, 1987." He originally introduced the proposal, which then covered only the Charleston office, last Oct. 15, when the housing and urban appropriations bill was being debated on the floor.

"I am very concerned that there have been staffing reductions" that would mean "that the district office will have to reduce efforts to expand the minority small business portfolio . . . . No additional moneys are required," he told his colleagues in urging approval.

It was approved that day and, with the language corrected to include Clarksburg, included in the spending bill in December.

Approval of the Bay St. Louis language apparently was never in serious doubt, as two Mississippians head the Hill's appropriations committees -- John C. Stennis (D) in the Senate and Jamie L. Whitten (D) in the House.

Sen. Daniel K. Inouye (D-Hawaii), fourth-ranking Democrat on the Senate Appropriations Committee, has been criticized for obtaining funds to build schools for North African Jews in France. But he also earmarked funds for back home.

The law contains "not less than $300,000" for additional part-time and temporary jobs in the Honolulu Customs District; $500,000 for research and training for hearing-loss assessments for native Hawaiian children, and a prohibition against relocating the Hawaii state office of the Farmers Home Administration from Hilo to Honolulu.

Using legislation to force an administration to continue operating government facilities in a Senate or House member's state or district that have been selected to be closed is a time-honored Capitol Hill practice. Take the language related to a C130E unit that was put in the bill by Rep. Norman D. Dicks (D-Wash.), third-ranking member of the House defense appropriations subcommittee.

The Air Force, according to a Dicks aide, decided late last year to deactivate the 16-plane unit as part of a cost-cutting exercise. It selected the only air transport unit on the West Coast, he said, "because the mission was not Air Force, but only serving as taxis for the Army."

Dicks demanded impact studies, including the costs that would be involved in securing alternative transport to the West Coast for Army maneuvers that would take place. He also sought support from the Army, which not surprisingly wanted the Air Force to keep transport planes near its West Coast units, particularly at nearby Fort Lewis, Wash.

In the end, Dicks insisted the mission remain, though with only eight aircraft rather than 16, and wrote his amendment to pay for that.

He was not alone in taking this route. The law contains, among other such items, $540,000 to be used only to operate the Naval Investigative Service regional office in New Orleans, and $53,375 to be "available only to operate the {defense} procurement outreach center" in North Platte, Neb.

Oregon, whose Mark O. Hatfield is the ranking Republican on Senate Appropriations and a member of the subcommittee handling the funds of the United States Information Agency, had two unusual grants written into law.

"Not less than $2 million shall be available for grant to the Oregon Historical Society to assist in the establishment of the North Pacific Research Center in Portland," it says.

The second grant involves a commercial sporting event featuring Olympic-type competitions that television entrepreneur Ted Turner has developed with officials of the Soviet Union. Under the law, $500,000, to be taken from USIA's private-sector exchange program, "shall be available only for the Seattle Goodwill Games organizing committee for cultural exchange and other exchange-related activities associated with the 1990 Goodwill Games to be held in Seattle, Wash."