Council of Economic Advisers Chairman Murray L. Weidenbaum said yesterday that the economy "has touched bottom" but that a recovery has not yet begun.

Weidenbaum acknowledged that the decline in economic activity this quarter has been greater than expected and said the administration forecast issued last month for 1982 was "probably a touch on the high side. Nonetheless, I continue to be optimistic about prospects for recovery later this spring and into the summer."

The administration expects unemployment, which was 8.8 percent in February, "to average in the vicinity of 9 percent" this year, but the rate should be down to about 8 1/2 percent by the fourth quarter, Weidenbaum told the Forecasters Club in New York.

"The precise timing, speed, strength, and duration of the current recovery, it should be acknowledged, will be affected by how quickly interest rates decline from the current high levels," he said.

Weidenbaum's assessment that the economic slide that began last July has ended was seconded by economist Alan Greenspan at a breakfast meeting with reporters. "The economy, as best we can judge, stopped going down in early January . . . The economy is probably in a very slight updrift that is not susceptible to measurement," said Greenspan.

Under normal circumstances, this "would have signalled the onset of a major recovery," explained Greenspan, a former CEA chairman. However, there is no sign of such a recovery in the orders being placed for steel and other basic materials. Instead, orders are flat or still falling because high interest rates are inhibiting the recovery, he said.

Greenspan went on to warn that interest rates are not likely to come down until "credible" actions are taken by Congress and President Reagan to lower future budget deficits. If the deficits are not lowered, there probably still will be an "anemic" recovery followed by continued "stagflation," he said.

Meanwhile, Lawrence Kudlow, associate director of the Office of Management and Budget, also told reporters that the recession is bottoming out but that the recovery this year "will not be as strong as generally hoped" because of strains in financial markets.

Kudlow called the recession a "necessary corrective step on the way to longer term economic recovery," and said it was "considerably lighter" than the one in 1974-75.

"Most of the signs we look at show the worst is behind us. We should see numerous signals of improvement in the second quarter," he said. Nevertheless, Kudlow added, "It may be, given the accumulated excesses and strains built into the financial sector over the last 15 years, the recovery will not be as strong as generally hoped."

"The healing process in the financial sector is very slow to take hold thus far," he said, and attributed the pace to public skepticism that inflation has eased permanently. "The American public is a Doubting Thomas," he said.

He also acknowledged that the government's heavy borrowing costs have influenced interest rates. He estimated total federal borrowing would absorb a record 40 percent of the capital raised this year and next.

"During recoveries, this credit demand will keep interest rates higher than they ought to be, and during recessions this credit demand will prevent interest rates from dropping to low levels," Kudlow said.

He predicted that interest rates will come down irregularly this year but added, "There will be no miraculous falling-off-the-cliff effect of interest rates."

Greenspan, however, said interest rates could come down significantly if the budget outlook is improved. He said financial markets would react very positively if they could believe that the budget deficits for 1983 and 1984 could be held to $120 billion and the one for 1985 to $110 billion. All those numbers are far higher than the administration's projections, but they would change the attitude in the markets if they were credible, he declared.