Three years of technical errors, confusing procedures and "serious errors in judgment" have thrown the federal government's coal-leasing program far off track, according to the final report of a special study commission.

The report, to be delivered to Interior Secretary William P. Clark today, represents a broad condemnation of the policies under which Clark's precedessor, James G. Watt, sought to put billions of tons of federal coal under lease as rapidly as possible.

"The commission found that the Interior Department since 1981 has tended to dismiss the risks of over-leasing and to exaggerate the risks of under-leasing federal coal," the report said. "As a result, the department has sought to lease too much coal."

The report essentially reinforces the arguments of environmental groups and members of Congress, who have contended that the administration's eagerness to lease coal, at a time when there was little demand for it, cost the government millions of dollars.

Instead of putting the coal program on a sounder basis after a 10-year moratorium, the report said, the effect of the department's "rigid determination" to meet its leasing goals "was to damage significantly public confidence in the government's coal-leasing process."

In addition, the report strongly criticized budget cuts and personnel reductions that have left the coal program short of management expertise, research and statistical data.

"We tried to stay away from personalities," said David F. Linowes, a University of Illinois professor who headed the coal commission. "But clearly we found that the management of the programs was confusing. It kept changing directions and causing controversies."

The report is the work of the commission that Watt characterized as comprising "a black, a woman, two Jews and a cripple," setting off a storm of outrage that eventually led to his resignation. Clark already has set up a task force to consider the commission's findings.

The commission did criticize by name two former Watt lieutenants, David Russell and William Pendley, who led the charge for the Powder River Basin coal sale in 1982 and have since been dismissed by Clark.

The report said that Russell and Pendley acted with "undue haste" in the face of evidence that the coal market was declining, first switching to a different basis of bidding and then sending "a clear signal" that low bids would be accepted.

"It is apparent to the commission that these officials had developed, well in advance of the sale, an overriding policy objective to lease a substantial amount of coal reserves in the Powder River Basin," the report said.

The government got $67 million for the Powder River coal; the General Accounting Office said the coal was worth $100 million. While the commission did not attempt to put a value on the coal, its report includes a table that suggests it may well have been worth nearly $100 million.

The commission concluded that Clark, "and perhaps the Justice Department," should investigate further.

The commission criticized Interior officials for seeking to please the coal industry, through a system of "leasing to meet industry demand," at the expense of the department's relationship with western states.

The report says that "significant real conflicts" exist between state and federal interests in coal tracts, but "the conflicts have been exacerbated unnecessarily by the actions of the Interior Department in recent years, a trend that the department should promptly seek to reverse."

Moreover, it warned that the federal government must consider "other public policy objectives" in managing its coal program, "such as promoting efficient land use and environmental planning."

Linowes said the commission, which approved all 36 of its recommendations unanimously, also was "troubled" by budget cuts that had trimmed the staff and scientific resources of the coal program.

The report cites cuts in the department's drilling program, for example, under which the government measures its coal tracts. Without adequate geological data, said Linowes, "You're really putting merchandise on the market when you're not sure what it's worth."