About $24 million in construction is scheduled for Northern Virginia's two state colleges in the budget proposed today by outgoing Gov. Mills E. Godwin.

The new buildings that Godwin's capital budget promises for George Mason University and Northern Virginia Community College are only small consolation for legislators who were again disappointed by Godwin's refusal to propose substantial appropriations for Metro subway construction.

The cities and counties in Washington's Virginia suburbs are laboring under a large and growing financial burden for Metro construction and bus and subway operating deficits, but Godwin recommended that the General Assembly approve only $3 million in each of the next years for Metro construction aid.

The college and Metro construction aid accounts for all the state building projects in the Washington suburbs except for a $110,000 maintenance projects at the Northern Virginia Training Center for the Mentally Retarded in Fairfax County.

The Metro aid will bring to more than $140 million the amount of state money or federal funds under state control that Virginia has committed to Metro, but it is far short of what Northern Virginia's legislators have sought.

Godwin specifically recommended against a long-term commitment by the state to help the suburban cities and counties pay off their Metro construction bonds. The House of Delegates Roads Committee, headed until this session by an old Godwim, ally, former Del. Lewis McMurran of Newport News, recently recommended that the state pick up 90 per cent of $127 million in Metro revenue bonds that now must be paid off by Northern Virginia localities. Godwin told the Assembly he thought this would be unwise.

It was once thought the revenue bonds would be paid off out of Metro fares. Now they represent about half the debt for Metro construction that the suburban cities and counties in Virginia will have to pay.

The college construction proposed for Northern Virginia amounds to about 9 per cent of $257 million in capital spending planned for the next two years in the Virginia budget.

Of this amount, only about $36 million is for projects that have not been previously approved by the Assembly.

The capital program includes $125 million in college, prison, parks and port facilities to be paid for with funds from a bond issue approved in the Nov. 8 election. The rest of the capital program is made up of projects approved when the current biennial budget was adopted in 1976 but not yet built.

Out of a college and community college construction program of $152.5 million, two academic buildings costing $13.7 million are proposed for George Mason and academic buildings costing $5.8 million are planned at the Alexandria campus of Northern Virginia Community College.

Construction worth $13.3 million, including two libraries to cost $11 million, is planned for the University of Virginia at Charlottesville. A high percentage at students there come from the Washington suburbs.

As he promised in his session-opening message to the Assembly yesterday, Godwin's proposed operating budget is designed to keep spending within the estimated growth in revenues from existing taxes, thus negating the need for new taxes. This results in a total operating budget of $9.019 billion for the next two years.

This only a 17 per cent increase in spending over the amount budgeted for the two years ending next June 30. the smallest biennial increase in 10 years. About 48 per cent of the budget is financed by general state taxes and the rest by federal grants, user taxes and special fees ranging from hunting licenses to college tuition payments.

The Godwin proposal recommends little change in the portion of state spending that for years has gone to the four major areas that account for more than 90 per cent of the operating budget.

These are education, 40.49 per cen; health and welfare programs, 25.74 per cent; transportation - chiefly highway construction and maintenance - 16.79 per cent; and police and prisons, 8.57 per cent.

State aid to city and county public school systems is scheduled to increase only 17.4 per cent over the next two years, reflecting the leveling off of the public school enrollment at about one million pupils.