As the Northeast sweats out the prospect of another summer of electricity shortages, much of the rest of the country is nearly drowning in power.

Government and industry officials say utilities in New England and New York may be forced to impose "brownouts," or brief periods of reduced voltage, if this summer brings a heat wave as intense as last year's.A power glut in other areas, meanwhile, is creating problems of a different sort.

Public Service Co. of New Mexico is drowning in surplus power. Last month, state regulators in effect penalized the utility for having invested in power projects that today are not needed. The utility, facing financial peril, stopped paying dividends on its stock.

The disparate power supplies raises a question of growing urgency: Why can't regions with too much power send their surplus to areas with shortages?

The answer lies in the fragmented nature of America's electric power grid.

While it is physically possible to transfer power from one area to another - and it is done regularly between some Western states - there is no nationally integrated transmission system and no master plan for relieving regional bottlenecks.

Ashley Brown, a member of the Ohio Public Utilities Commission, calls the nation's inability to balance its regional power needs "a travesty."

"If you came from Mars and looked at the New England states . . . and at the Midwest, which we can say charitably is endowed with no shortage of capacity, and you saw that we can't get power from one place to another, there is no logical explanation for that," he told a meeting of state utility regulators.

Some officials say the Northeast's power squeeze may be even more severe in a few years as growing demand for electricity outstrips the region's stagnant supply.

In the Pacific Northwest, the Bonneville Power Administration has so much excess electrical generating capacity that it is holding back on conservation measures that could save power equal to the yearly output of 11/2 nuclear power plants.

Despite the regional disparities, the United States as a whole enjoys a comfortable balance between electricity supply and demand. In 1987, the latest year for which such figures are available, the nation's utilities had the capacity to provide 23 percent more power than was needed. The margin of reserve power varied, however, by region.