Since last July area savings and loan associations have experienced customer withdrawals of more than a quarter of a billion dollars. Nine of the 21 members of the Metropolitan Washington Savings and Loan League have deceased their reserves during the first quarter of 1980, an indication of operating losses or tax write-offs.

The savings and loan industry is facing its worst crisis in postwar history -- and this area is no exception, raising issues that will be discussed as members of the Washington league gather next weekend at the Homestead for their annual convention.

In the first three months of 1980, net new savings of thrift institutions across the country plummeted $9 billion, or 88 percent compared with the same period in 1979, according to the U.S. League of Savings Associations. Mortgage lending sank 30 percent to $14 billion, roughly the low experienced during the first quarter of 1976. Net income after tax dropped 34 percent to $615 million.

The trend continued in April with withdrawals exceeding deposits by $815 million, and mortgage lending 20 percent below the previous month and 48 percent below April of last year.

Actually, first quarter earnings were better than expected, noted Richard G. Marcis, chief economist of the Federal Home Loan Bank Board. That was due primarily to penalties paid by depositors who cashed in their lower yielding money market certificates prematurely to buy higher yielding ones while interest rates were soaring. However, with penalty payments taperingoff, and mortgage origination fees still stagnant, Marcis predicts that the thrift industry as a whole will experience negative earnings for the current quarter before it again begins to make money later this year.

Expressed as a return on assets, savings association profits averaged 40 basis points (each basis point is a hundredth of a percent) in the first quarter. For the year as a whole, the average is expected to be about 34 basis points, compared with 67 basis points last year.

If this projection proves true, it will mean that 1980 will be the worst year in thrift annals.

During the first quarter of 1980, thrifts in the Washington area had an outflow of $88 million, compared with a gain of $28 million in the same period last year. Mortgage loans closed dropped from $137 million in the first three months of 1979 to $122 million this year. The 11 percent drop was smaller than the national average due to the large number of commitments honored, according to the FHLBB.

Net income of regional S&Ls is not publicly available from the bank board. However, estimates based on percentage of total assets put the income of the 16 District thrifts at about $5 million during the first quarter of this year, compared with $8 million in the same period last year.

One president admitted last week his profits were down 75 percent this quarter. Bob Long, an analyst with Ferris & Co., estimates that at least one-third and perhaps as many as one-half of the area's S&Ls are now operating in the red.

Nevertheless, that does not mean area S&Ls are in danger of failing or that customer deposits are in jeopardy. The percentage of their deposits in reserve (the equivalent of profits set aside) is well above the 5 percent required by the bank board and considerably higher than the national average of 6.8 percent.

The creation of money market certificates in June 1978 prolonged the ability of thrifts to continue lending longer than they would have otherwise been ale to do by discouraging customers from withdrawing their funds to place them elsewhere.

This spring Congress passed landmark banking deregulation legislation which will allow -- indeed, oblige -- thrifts to begin to compete head to head with commercial banks and other financial institutions. They will have significant new asset powers such as the ability to make consumer loans and renegotiated rate mortgages, issue mortgage backed securities and establish checking-with-interest or NOW accounts.

The executives predicted avid competition between banks and thrifts to lure deposits for NOW accounts when they begin next Jan. 1.