Interior Secretary James G. Watt yesterday outlined a speedup in the sale of offshore oil and gas leases, beginning with a controversial tract off California that environmentalists say is a major wildlife area with skimpy oil reserves.

California Gov. Edmund G. (Jerry) Brown Jr. immediately accused the Reagan administration of "mismanagement" of natural resources areas and said he would file suit in federal court to stop the California sale.

Watt, appearing at a joint press conference with Energy Secretary James Edwards, said his department is rewriting the five-year leasing schedule for the outer continental shelf (OCS) that the Carter administration announced last June in order "to increase the pace, acreage and quality of offerings."

The policy, Edwards said, is part of President Reagan's stress on domestic oil production. "There is no confusion in this administration," he said.

The new leasing plan, to be detailed in draft form in May, will add six sales to the 36 that President Carter had proposed and will accelerate the schedule on some of the original 36, notably in Alaskan waters. Areas that oil companies consider promising will be moved up in the schedule and the acreage in each one will be increased.

"Offshore oil and gas activities have had an excellent environmental record" that is "dramatically better than that of tankers carrying foreign oil, an alternative source of oil which OCS production can displace," Watt said. A spokesman for the American Petroleum Institute said its members were "encouraged" by that recognition.

Environmental groups, however, were not convinced. "The plan is risky and irresponsible," said Kathy Smith of the Friends of the Earth. "In order to keep up with this overly ambitious program, environmental concerns will be downplayed or disregarded." She noted that the Department of Interior's budget for studies of environmental conditions had been cut from $21 million in 1980 to $8 million for 1982. Others in the group said oil leasing is proceeding so fast under current policy that industry has shortages of the equipment and people needed for exploration.

In California, Gov. Brown and several congressmen deplored Watt's decision to proceed with a scheduled lease sale on a package of tracts in the Santa Maria basin off the coast of San Luis Obispo, 300 miles south of San Francisco. "This action ignores the consistent and overwhelming opposition of state, local and congressional officials, the chambers of commerce of the affected areas and the citizens at large, and cites only a poll commissioned by the oil lobby," Brown said. "It forces me to conclude it is mismanagement of the country's resources."

Watt said a Field Research Organization poll found 16 percent of Californians opposed to offshore drilling.Brown and more than half the state's congressional delegation had opposed leases in the northern 34 tracts of the Santa Maria basin on grounds oil reserves there are minimal and the area is a major fishing ground and marine mammal habitat.

They also opposed plans to lease in four northern California basins, and Watt yesterday said a decision on those will be made in late May or early June. "We will mesh their concerns with the national interest," Watt said.