BECAUSE CONGRESS is showing no inclination to take the obvious stop needed to curb the national appetite for oil -- a sharp increase in the federal gasoline tax -- the states have a rare opportunity. They can, if they will, exercise leadership on a major national issue, help ease the country's dependence on foreign oil and solve their own pressing problems at the same time. They can do this by substantially increasing their own motor fuel taxes.

We know -- the odds are that state governments will not seize this chance. They are not exactly famous for exercising leadership when it involves politically unpopular tax increases. But almost every state government is in desperate need of more money for highway maintenance and construction. Either that money is going to be raised by increasing some state taxes, or the highway system is going to go to pot.

The story now being told about Virginia's highways is typical. Highway Commissioner Harold W. King says the state needs to spend $53 million more than existing taxes will raise in the next year. That's without counting any substantial contribution by the Department of Transportation to Metro or other mass transit systems in the state.

What's happened is that the revenues raised by the taxes earmarked for highway projects, primarily taxes on motor fuel, have not gone up nearly as fast in the past decade as construction and maintenance costs. Nationally, state governments collected 61 percent more in fuel taxes in 1978 than they did in 1968. But maintenance costs went up more than 110 percent and construction costs more than 150 percent in the same 10 years.

The result is that half the country's paved roads are said to be in fair or poor conditions, while one out of every five bridges is in need of major repair. Unless the states step up their spending on maintenance and repairs soon, billions of dollars worth of highways will deteriorate so much that repair will no longer be possible.

The response in many states -- Maryland is among them -- has been to consider increasing taxes on motor fuel by a small amount (one cent or two cents a gallon) while increasing other taxes as well. A better response would be to put the burden of additional transportation financing, not just that required for highway projects, on the motor fuel taxes. It makes little sense for the states to tax motor fuel at about 10 percent now after taxing it at more than 20 percent in the years when oil was plentiful. Yet that will be the result of the one-cent and two-cent increases under consideration.

If the states were to be bold about this and increase the motor fuel taxes by, say, 5 cents or 10 cents a gallon (using the surplus to reduce other taxes), the way would still be open for Congress to pass the even higher federal tax that is needed. It could simply mop up the difference between what the states take and what is needed to get oil consumption under control.