The District of Columbia government is spending $6,065 for each student in its public university -- more than any state except Alaska, according to a researcher at the National Institute of Education, a branch of the new U.S. Education Department.

Kent Halstead, the economist who compiled the cost statistics for the institute, said the high college subsidy here is almost double the national average of $3,173 per student during the 1979-80 academic year.

He said it is caused partly by the low tutition at the University of the District of Columbia -- just $199 next fall -- and partly by its high salaries, high staffing levels and other costs.

"It all may be completely justified," Halstead said. "But someone could raise the specter that this is a near-extravagant level of funding, and Mayor (Marion) Barry and the City Council will have to face the question: 'Do they want to run it this well?'"

In an interview, UDC president Lisle C. Carter said comparisons between the District's university and those in the 50 states were difficult because UDC concentrates on low-income students with poor high school preparation who require small classes and counseling.

But Carter agreed that UDC's costs are high and its administration and faculty relatively large. He said he expects to make firm proposals in September to carry out a consultant's report which suggested trimming the staff by about 20 percent.

"We want to end up with a (student-faculty) ratio overall of 15 to 1 (instead of last spring's 12 to 1)," Carter said. "Whatever it takes to get us there we will do."

"The staff is getting smaller and it will continue to grow smaller by attrition," Carter said. "There probably will be some adjustments by the fall of 1981. It will take that much time because of the lead time you need in academic institutions. . . . I've told the mayor and council we are attempting to move in an orderly way and meet our responsibilities for retrenchment without disruption. We want to make sure nothing is done in an arbitrary fashion, and we create the structure of a consolidated university."

Though some UDC vacancies have not been filled, there have been no layoffs or program cuts at the university, despite major cutbacks elsewhere in the financially strapped city government, including the layoff of about 650 public school teachers.

According to figures compiled by Halstead, government spending per student in Washington's public college was 91 percent above the national average.

By contrast, spending per student in the D.C. public schools is about 37 percent above the national average, according to Education Department figures.

D.C. budget director Gladys Mack said major cutbacks are being made in the public schools and not in the university because the number of school children is declining rapidly while university enrollment appears to have stabilized. It is down, however, about 13 percent from the total enrolled in 1975 at the three public colleges that merged to form UDC.

Mack, whose husband Julius is a UDC chemistry professor, said the District government had not made comparisons with public colleges elsewhere in setting UDC's spending.

"There's a great deal of support for higher education in this community because it's needed and it's new," Mack said. "It's still really a fledgling university, and we realize how important it is to make it strong."

She said Mayor Barry had approved $50.7 million in D.C. funds for the university for the fiscal year starting Oct. 1, compared to the $47.6 million (excluding tuition) budgeted this year.

The University of D.C. was formed in 1977 by a merger of the District's three public colleges -- Federal City College, Washington Technical Institute and D.C. Teachers College.

Carter said the merger itself is one reason for the university's high costs because it is "still in the process of consolidation . . . It's not an institution that has been organized rationally from scratch."

For example, Carter said, under the D.C. law creating the university, all administrators of the three previous colleges have their pay and positions protected. The rank of professor also is protected, and many professors continue to teach their old courses even though these may overlap with what others are doing. Three computer science programs -- all under capacity -- offer similar courses, for example.

According to a report by the Academy for Educational Development, a nonprofit group that is serving as consultant in reorganizing the university, UDC offered 11 different freshman-level French courses in its 1979-80 catalogue. Almost all the classes had fewer than 10 regular students.

Classes were even smaller in the education departments, which merged faculty from Federal City and D.C. Teachers, and averaged just eight students per faculty member.

University officials said the small classes were deliberate in many lower level courses to give careful attention to students whose achievement was low in high school.

However, many of the junior and senior classes are small because few students reach that level. Last year about two-thirds of UDC students were freshmen.

In its report, prepared last fall, the Academy for Educational Development said the best comparison for UDC's costs would be with other urban universities that largely enroll low-income students.

The Academy picked eight such universities, including Morgan State in Baltimore and Norfolk State in Virginia. Using 1978 date, it calculated that UDC's cost per student was about 80 percent higher than the average for the others.

Two others factors involved in UDC's relatively high costs are:

Low tuition. At $169 for local residents last year, UDC's tuition was the lowest at any state university in the country. Tuition receipts amounted to just 6 percent of the D.C. government's spending for the university, the lowest proportion in the country. Nationwide, tuition averaged 27 percent of government costs for public higher education.

High salaries. According to the American Association of University Professors, UDC faculty salaries are the highest in the Washington area and among the top 5 percent of all colleges around the country.

"We're locked into the pay scales we inherired when UDC was set up," one administrator said. "They've just been marching up along with federal workers, and that's a lot better than professors have been doing around the country."