ON. JOHN N. DALTON wasted no time throwing cold water on Northern Virginians' legislative hopes for a shift of their tax burden away from property taxes. In his curtain-raiser appearance before the 1979 General Assembly -- and without even consulting the Northern Virginia delegation to the state legislature -- the governor announced that he flatly opposes a local sales-or gasoline-tax increase to help finance public-transportation needs, including Metro as well as road projects. Not only has Mr. Dalton dealt a serious blow to a perfectly reasonable financial proposal -- one on which local leaders throughout this metropolitan area had agreed -- but his position also reflects a misunderstanding of what that proposal involves.

The Northern Virginia legislators' effort stems from a decision by the elected officials of this region to seek taxes dedicated to help pay for the Metro system's capital and operating costs -- and to uphold their end of financial agreement with the federal administration. They went to Richmond ready to try for permission to raise the sales tax in their region from 4 percent to 5 percent and to earmark the additional percentage point to transportation projects. But as Del. Richard R. G. Hobson (D-Alexandria) noted at the opening session of the Assembly, "The governor has missed the whole point of our proposal by referring to it as a tax increase. The bill guarantees a dollar-for-dollar recuction in property taxes to offset any sales-tax increase."

It was John Dalton, voters may recall, who made much in his campaign pitches to Northern Virginians about the strong taxpayer resistance in this part of the state to any more pressures on property taxes. And he appeared to sympathize with the support of voters in this area for completion of Virginia's sections of the rail system as a necessary part of an efficient tranportation system. But this week, Mr. Dalton defended past support of Metro by saying that Virginia has advanced or committed "more than $200 million to Metrorail in state funds or federal funds which state action has made available." That is a misleading figure, since it includes federal money, transfers of highway money and so on; the total state capital contribution to Metro through fiscal 1980 comes to less than half of that.

In any event, the proposal is not a matter of creating a separate regional tax-raising authority or a "raid" on Virginia money by out-of-state interests. Metro is a vital part of Virginia's transportation system -- and the legislators from this area should persist in their legislative effort this year despite Gov. Dalton's wrongheaded opposition.