In the Defense Department budget, where a billion dollars is little more than walking around money, the Navy's Project ELF seems like small change. ELF is a proposed ''extremely low-frequency'' system for communicating with our strategic ballistic missile submarines (SSBNs). It will cost only $230 million over the next five to seven years.
But ELF is a military Tinker Toy. It is not needed.
The proposed system couldn't possibly survive a nuclear attack. Present plans call for its feeder lines to be strung out on telephone poles over 56 miles of forest in Michigan's Upper Peninsula near K. I. Sawyer Air Force Base, connecting up with an existing transmitter and its 28-mile antenna near Clam Lake, Wis. The clothesline-like contraption could be undone by any amateur terrorist.
If ELF is worthless in war, it also is unnecessary in peace. But the Navy wants it anyway. Old projects die hard.
The government began research on an extremely low-frequency communications system in 1958. The Wisconsin test facility was completed 10 years later. The big daddy of ELF was Sanguine, a billion-dollar system that would have included 41 percent of Wisconsin, with a buried antenna ''farm'' 6,600 miles long.
The Navy wanted Sanguine for one main reason: The system was believed capable of withstanding a nuclear attack. But as Soviet technology improved, Sanguine was pronounced nonsurvivable. This led to the demise of plans for the project in 1973.
Two years later, Sanguine was reborn as Seafarer. The scaled-down communications system would have covered 2,400 miles. President Carter put an end to Seafarer in 1978.
Pentagon planners retaliated with the ''Austere ELF'' project, the immediate predecessor of the present ELF. Its antennas would have extended for only 130 miles in Michigan and 28 in Wisconsin.
None of these stepchildren of Sanguine was alleged to be survivable. The original justification for the project - and the only viable one - was shoved aside when Sanguine was shelved. But once conceived, and regardless of its lack of a raison d'etre, the communications system has had a life of its own. Since 1969, $135 million has been spent in researching the system.
The Navy has brought forth new reasons to justify its existence. These reasons don't wash.
Unfortunately, where the new mini-ELF is concerned, the Reagan administration has failed to scrutinize the fine print. And the Congress already has authorized an additional $35 million for the project. But Congress isn't expected to consider full funding for several weeks. However belatedly, Project ELF still can be ended. And it should be.
During wartime, the Pentagon - if there still is a Pentagon - would have to rely primarily on its TACAMO fleet of aircraft as a link to the strategic submarine force. That system is on constant alert - ready for duty in any emergency.
A number of peacetime communication systems, using several different radio frequencies, also are in operation. Very low-frequency (VLF) shore stations, located at strategic points around the world, are a vital part of the communications network. According to a 1979 General Accounting Office report, two of these stations - one in Cutler, Maine, and another in Australia - ''. . . provide VLF signals to virtually all ocean areas.'' Other stations provide backup to the two main transmitters.
The peacetime communications systems are unique in nothing so much as their redundancy. The GAO report questioned the need for another peacetime system, and cited the already existing duplication as one of the reasons. Another was that our SSBNs are ''extremely survivable now and will continue to be survivable in the forseeable future.''
Military experts acknowledge that our missile-carrying submarines are no more vulnerable than they were two years ago - if anything they are less so. Why then does the Navy insist on Project ELF?
Our present methods of commmunicating with our SSBNs have one serious flaw, says the Navy. If a submarine is to get a message, it can either deploy a floating wire antenna near the surface, or tow a buoy antenna at a depth of 12- 40 feet. If the Soviets happened to be in the vicinity of one of our submarines, they might detect the buoy, the antenna, or their wakes with radar, infrared sensors, or acoustic devices.
The Navy doesn't want the Soviets charting its submarine maneuvers. As spies of the sea - underwater agents, as it were - submarines lose their viability if they are found out.
But detection isn't likely . An antenna or a buoy is a mere mote in the vast eye of the sea. According to the GAO, the Soviets lack ''broad ocean search capability.''
Project ELF will not make the US less vulnerable. And even if it is completed on schedule by 1985, it will soon be outmoded by new technology. A new communications system, using blue-green laser beams that can penetrate to considerable ocean depths, now is being developed.