Opponents of the Energy Security Act say it would give U.S. presidents too much power and that the legislation, which would cap our growing dependence on imported oil, addresses a nonexistent national security threat.

They should pay more attention to events in the Persian Gulf.

This legislation is incorporated in the trade bill reported by the Senate Finance Committee in May which the Senate is debating this week. It does not expand authority U.S. presidents have had for more than three decades, under section 232 (b) of the Trade Expansion Act. If enacted, in fact, it may well mean that no U.S. president would be called on to use far more awesome powers to protect our national security interests. The Persian Gulf situation gives us a whiff of what those powers entail:

With the stroke of a pen, the president may soon "reflag" 11 Kuwaiti tankers as U.S. merchant vessels. This action, which would put us squarely on the side of Kuwaiti ally Iraq in the Iran-Iraq war, is being contemplated at the insistence of the emir of Kuwait, who threatens otherwise to turn to the Soviet Union for assistance.

In the wake of the attack on the U.S.S. Stark, the president has increased the presence of U.S. air and naval forces in the Persian Gulf.

The president has ordered U.S. forces to man their battle stations while convoying ships in the Persian Gulf.

The president's powers under the Energy Security Act would be puny by comparison with these actions and others he may be forced to take if we fail to limit our dependence on Persian Gulf oil.

The legislation would work this way. Each year the president would be required to prepare a three-year projection of U.S. energy supply and demand patterns. If in any of those years the level of imports threatens to exceed 50 percent of the oil consumed in this country, the president must draw up a program for holding dependence below that level.

The legislation requires the president, in preparing this program, to use authority U.S. presidents were granted more than 30 years ago.

Sens. Robert Packwood and Bill Bradley {op-ed, June 22} argue that the Energy Security act "fails to distinguish among sources of foreign oil. Clearly," they say, "oil from the Persian Gulf is less secure than oil from our neighbors in Mexico, Canada and Venezuela."

The shocking truth is that our imports have already climbed so high that we could not meet our present need for imported oil even if we bought every barrel produced by Mexico, Canada and Venezuela.

Since this is the case, what happens as our need for imports increases in the years ahead?

The fact is that as our dependence on foreign oil grows, the vast bulk of that new oil must come from the Persian Gulf and the Persian Gulf alone.

Our dependence on foreign oil is today at about the same level it was in 1973, when the first Arab oil embargo hit. When our dependence rises to 50 percent, our vulnerability to another oil embargo will be substantially higher. A repetition of the 1973 embargo would cut real income in the United States by more than $700 billion over five years, cause our inflation rate to double and increase unemployment by 25 percent.

Opponents assert that the Energy Security Act would be used by presidents to run roughshod over environmental laws and to impose gasoline rationing.

Both these claims are wrong.

In the more than 30 years of its existence, section 232 (b) has never been used to suspend environmental regulations. It would make no sense for a president to respond to this legislation by selling oil and gas leases on environmentally sensitive lands such as the Arctic National Wildlife Refuge. It would take more than a decade for these lands to come into production, while he would have three years or less to show results.

As to gasoline rationing, a Draconian step to allocate limited supplies of fuel, opponents have it backward. Rationing would be much more likely if the Energy Security Act were defeated and our dependence on uncertain foreign imports were allowed to soar past the 50 percent mark.

Opponents have an obligation to propose an alternative for protecting their constituents from increasing vulnerability to a foreign oil cutoff as our dependence on imports rises.

As of now, though, the only alternative to the Energy Security Act is continued reliance on a market dominated by OPEC and a return to gunboat diplomacy. The writer is a Democratic senator from Texas.