The Department of Energy's state conservation program has failed to reduce energy use as much as predicted because of "overly optimistic goals" and energy savings claimed for the program have been "overstated and unsupported," a new report from the General Accounting Office says.

Congress is considering a Reagan administration proposal to kill the State Energy Conservation Program (SECP), and in the process is examining energy conservation block grant proposals, which would provide funds for similar purposes.

GAO declined to take a position on the dismantling issue, but recommended that, if the SECP is retained, it be reorganized to concentrate federal dollars in the most effective programs.

Congress established the SECP in 1976 after the Arab oil embargo had produced enormous public interest in energy conservation. The program, which has doled out $288.9 million in federal funds to the states since 1976, was intended to encourage states to reduce their energy use, with an initial goal of a 5 percent cut by 1980.

States were required to develop comprehensive energy conservation plans, which included lighting, thermal and insulation efficiency standards for buildings, right-turn-on-red regulations and car-pool programs.

While the GAO found that the program forced states to start managing their energy programs more effectively, it also found that a disproportionate amount of federal money was spent on ineffective programs.

For example, in New Jersey, one of the six states on which the study concentrated, 19 conservation programs accounted for 80 percent of expenditures but 13 percent of energy savings in 1980.

The six states had projected for 1980 energy savings of 368 trillion British thermal units, a standard measure of energy, as a result of various residential conservation programs, but reported actual savings of 155 trillion BTUs.

The GAO found that goals for residential audit programs were "overly optimistic," particularly programs which did not require on-site inspection by trained auditors