Back in 1975, in response to the OPEC oil embargo, the United States began storing what it hoped would become a year's supply of crude oil. The concept was to build up an emergency reserve in case the flow of imported oil was ever cut off again.

That was a good idea, but the growing U.S. appetite for imported oil is making the reserve less and less effective.In the salt caves of Texas and Louisiana where the oil is stored, there are 565 million barrels of government-owned crude. That amount could replace about 70 days worth of imports at the present rate of 8 million barrels a day. Four years ago, even though there was less oil in the reserve, the storage was equal to 115 days of imports.

Clearly, as imports grow, the reserve is able to make up for a smaller share of what the nation uses. At present, the United States relies on imports for about 44 percent of its oil supplies. The highest rate in history was 46 percent back in the 1970s. The Energy Department estimates imports will account for 65 percent of U.S. oil consumption in another decade.

Those figures are troubling. They represent a rise in consumption at the same time that there is a drop in domestic oil production. In addition to the question of national security and dependence on foreign oil, the imports contribute heavily to the trade deficit.

The target for the strategic oil reserve is 750 million barrels, a figure set by Congress. But that amount is turning out to be too small and perhaps should be raised to one billion barrels. That would take $6 billion and another 10 years to achieve.

In a time of severe budget deficits, the money is a problem. And if imports keep rising over a 10-year period, even a one-billion barrel reserve may be less than adequate,

The most effective long-term answer is conservation - meaning smaller, more fuel-efficient cars. Yet U.S. automakers keep building bigger cars and keep objecting to government-imposed mileage standards.

Reducing our use of oil must be faced now, not later, even if it takes something like a tax on imported crude. Delay is only going to make the problem bigger and that much harder to resolve.