Greater Washington savings and loan associations, plagued by high interest rates, stand to lose up to $40 million in the first half of this year. i

However, their reserves, or retained earnings, are large enough that they theoretically could continue to lose money at this pace for 10 years before becoming insolvent. Even if they should fail, deposits are insured to $100,000 by the Federal Savings & Loan Insurance Corp., an agency of the federal government.

Statistics compiled by the Federal Home Loan Bank of Atlanta from reports submitted by 42 federally insured S&Ls in the Washington metropolitan area reveal that their net worth dropped by $15.6 million during the first quarter, to $5.43 billion. Of the 115 S&Ls insured by the Maryland Savings Share Insurance Corp. throughout the state, the 68 largest (with assets over $3 million) lost $5 million in the same period. Their net worth is $100 million.

Net worth is the best indicator of an institution's solvency. But a decrease in net worth does not mean the money is forever lost. Were interest rates to drop sharply, losses quickly could be turned into gains. Economists say that it would take several months of interest rates in the 11-to-11.5 percent range for S&Ls to break even this year -- admittedly an unlikely prospect.

The second quarter threatens to be worse than the first. Dale Riordan, chief economist of the National Savings and Loan League, projects that losses for all savings and loans in the country will climb from $688 million during the first three months to $800 million or $1 billion in the second quarter, for a half-year total of from $1.5 billion to $1.7 billion. Jonathan Gray, a securities analyst with Sanford Bernstein & Co., is more pessimistic, prediciting first-half losses as high as $2.5 billion.

At Riordan's national rate, first-half losses for FSLIC-insured thrifts in the metropolitan area could amount to $34 miillion to $37 million. MSSIC losses could come to $10.8 million to $12.3 million. At Gray's national rate, the local losses would be considerably higher. A loss of $40 million in the first half of this year amounts to a loss of 63 basis points, or 63 cents on every $100 of assets on an annual basis.

Worse, both men are pessimistic about the rest of the year. In his most recent forecast, published this week, Riordan says: "The second half of the year should be approximately the same as the first half, with perhaps a little improvement in the fourth quarter." Gray predicts losses for the year could run to between $6 billion and $8 billion without a decline in interest rates.

The thrift industry -- savings and loans and mutual savings banks -- is facing its worst crisis since World War II. Lenders are saddled with low-yielding mortgages, while having to pay market rates on two-thirds or more of their deposits and borrowed funds. The average yield coming in on those mortgages is 9.5 percent, whereas they now are paying out 15 percent or more on certificates of deposit. Moreover, loan origination fees have just about dried up, since few people can afford mortgages at 17 percent.

Congress and federal regulators have given thrifts increased asset powers or different ways of making money, including commercial loans and credit cards. oOnly a few have been able to take advantage of these. The biggest change is the adjustable mortgage loan, which eventually will match up S&Ls' assets and liabilities. But it will take some years to bring up the yield on their loan portfolios.

Deposits also have been drained by money market mutual funds. Last month all federally insured thrifts had net withdrawals of $2.1 billion, just a bit less than the $2.2 billion outflow in March. Washington's l2 thrifts lost $73 million in deposits last month.

Federal regulators actively are discussing the possibility of allowing thrifts to establish money market funds or equivalent market-rate repurchase agreements or certificates, in an effort to allow federally insured thrifts to recapture some of those dollars. State-chartered thrifts, on the other hand, have been able to retain more of their deposits because they can pay more interest on passbook accounts.

The FSLIC has asked Congress for additonal funds to shore up technically insolvent thrifts until interest rates fall or mergers can be arranged. Regulators are talking more about permitting interstate mergers and even intraindustry mergers, although the thrift industry still is bitterly opposed to letting banks take over its ailing members.

Just how bad off are S&Ls? Collectively, the thrifts have been trying to make their difficulties known to federal regulators, congressmen and anyone else in a position to help them, without at the same time frightening the public and touching off panic withdrawals. Individually, thrifts in trouble are reluctant to tell their competitors or their depositors. The Federal Home Loan Bank Board estimates that 60 percent of them now are operating in the red. The Washington area is no exception.

Statistics for the first quarter largely are unavailable except in aggregate. The Metropolitan Washington League of Savings Associations, which formerly reported data, voted earlier this year to change its policy. The Federal Home Loan Bank of Atlanta also refused to release figures, whereas the Federal Home Loan Bank Board in Washington publishes individual data only semiannually.

End-of-year 1980 data show the profitability of federally insured S&Ls in greater Washington was below the national average. A study of 146 S&LS in the three jurisdictions shows that they earned an average profit of 7.2 cents for each $100 of assets during the year, compared to 13 cents for S&Ls throughout the country. The local return was skewed by the enormous loss of a single association, which the FSLIC now is trying to merge with another S&L.

For 1980, the average return on assets of federally insured Virginia S&Ls was 0.108 percent, or 10 cents earned for every $100. For Maryland, it was 0.0721, and for the District it was a loss of 0.191.

The statistics also reveal a wide variation in performance among associations. For example, an analysis of income in relation to assets shows that at the end of 1980 only four out of 13 District S&Ls were opening in the black. Washington Federal was first, with earnings of $1.2 million for the year, for a return of 0.407 percent on assets; Eastern Liberty, last with a loss of $2 million, had a negative return of 0.965 percent. Washington Federal's president, James Harris, predicts that this year his association will lose $700,000 in the first half. Eastern Liberty is being merged into National Permanent.

In Virginia, 45 out of 77 associations were in the black last year. The best return on assets, l.2 percent, was shown by Standard-Grundy, an S&L with only $3 million in assets. Among the largest S&Ls, the best record of 0.845 percent belonged to First American of Woodbridge. The worst return was chalked up by Family of Springfield, which had a loss of $560,000 for a negative return of 0.97l. It since has been merged. Other Virginia mergers include First Federal of Arlington with Arlington-Fairfax, Washington-Lee of McLean with Virginia First of Petersburg, and Heritage and Colonial in Richmond.

But the District and Virginia losses pale beside that suffered by County Federal of Rockville, which lost $4.75 million last year for a negative return of 3.5 percent. County is being merged into Metropolitan by the FSLIC. Nineteen out of 68 federally insured S&Ls in Maryland operated in the red last year, 49 in the black. The best record was made by Leeds Federal of Baltimore, with a l.2 percent return on assets. Among the largest S&Ls, Maryland Federal of Hyattsville had the best record: 0.378 percent.

Of the 115 MSSIC associations, 77 operated profitably last year. Most of these were small, often family-owned S&Ls, which have the bulk of their funds in low-interest accounts. Of the 29 with assets over $10 million, 13 showed losses. MSSIC associations, which hold $2 billion, or 20 percent, of the insured deposits in the state, had assets of $2.4 billion as of March 1981. Six mergers have taken place so far this year, four of them among very small institutions. Among all Maryland S&Ls, 23 mergers have occurred within the past 18 months.

The area's thrift executives generally have adopted a grin-and-bear-it attitude, confident that their sizable reserves of three quarters of a billion dollars will tide them over.

A few, however, are openly grinning. James Russell, president of Mount Vernon Savings and Loan of Alexandria, is one. His earnings for the first 10 months of his fiscal year ending June 30 were up 200 percent to $56,957. Deposits were up $6 million, primarily in jumbo certificates. Because it was established in 1976, Mount Vernon has a higher yield on its loan portfolio -- 11.021 percent -- than older S&Ls that still have 5 percent and 6 percent mortgages on their books. At the helm for just a year, he keeps Mount Vernon very liquid -- 20 percent -- in anticipation of better days. But Russell, 32, considers this adversity "a great opportunity to make our position strong, by being very aggressive."

Also optimistic is George Cain, vice president for savings operations at Dominion Federal of McLean. Founded in 1974, Dominion Federal has assets of $155 million and a mortgage loan portfolio yield of 11.51 percent. All loans are sold off in the secondary market, but the S&L receives $360 million for servicing those loans. Its cost of funds is 11.01 percent. For the first three months of this year Dominion had net income of $72,000; April netted $25,000. Deposits grew by 80 percent in the past year. Cain attributes success to aggressive marketing, including the free use of safety deposit boxes with savings accounts.

John Hanson Savings and Loan of Forestville, with assets of $186 million, eaned $456,000 in the past 10 months. It has been closing between $5 million and $6 million in loans each month, gradually increasing the yield of its portfolio to 11.7 percent, according to executive vice president Jerry Whitlock. The key to his success: "Greater flexibility in what we can pay, greater flexibility in our mix." Commercial loans now account for 16 percent of his portfolio, up from 11 percent. Hanson recently announced plans to acquire Metropolis of Baltimore.

Whitlock sees the rest of this year as a little worse than last for the majority of S&Ls. As he says, "Anyone who is just operating in the black now has a major accomplishment."