Maryland savings and loan associations, like their counterparts across the country, can expect to wind up this year in the red if the recession deepens. Moreover, the recovery will be slow, with 1981 earnings only half those of 1979.

This grim forecast was presented yesterday by economist Donald M. Kaplan at the annual meeting of the Maryland Savings and Loan League. The thrift executives met at the International Hotel near Baltimore Washington International Airport.

Their convention originally was scheduled to be held at a resort hotel on Marco Island off Florida's southern Gulf Coast but was canceled in April as an economy move when red ink began to appear on members' balance sheets.

The league now finds itself being sued for $200,000 by Marriott Corp., owner of the hotel, for failing to honor reservations for 175 rooms for four nights.

League President Charles H. Kresslein Jr. offered the hotelier $10,000 with a promise to hold functions in other Marriott hotels. However, negotiations broke down and the company filed suit April 23.

Kaplan, formerly with the Federal Home Loan Bank Board, offered forecasts based on both quick and deep recessions but indicated he thinks the latter is more likely.

According to his economic simulation, federally chartered Maryland S&Ls, with $7.4 billion in assets, will have two negative quarters this year and a net annual loss of $170,000, or a negative return on assets of 0.01 percent. Next year they can expect net income to climb to $21.48 million, or just half the $42.5 million they made in 1979.

Under the more optimistic projection, the thrifts would close out this year with net income of $10.2 million and by next year would be approaching the $51 million boom of 1978.

Kaplan's forecast for the industry as a whole runs parallel: in the first example, a loss of $40 million in 1980 compared with net income of almost $4 billion last year, for a negative return on assets of 0.02 percent. With a quick recession, S&Ls could expect positive earnings of $490 million.

On the other hand, Maryland S&Ls continue to show a lower rate of return on assets, the classic profitability measure, than do American thrifts as a whole.

In 1975, the state's S&Ls had a return of 0.557 percent compared with the U.S. average of 0.477 percent. The trend shifted the next year, and by 1979 Marylanders had a return of 0.571 percent, whereas the national average was 0.683 percent. Kaplan attributed the backslide to usury ceilings and mortgage point restrictions, since eliminated.

In any case, Maryland thrift executives emphasized yesterday, they have sufficient reserves to withstand any losses, and customers should not fear for the safety of their money.

James W. Christian, senior economist of the U.S. League of Savings Associations, told the conference he still expects earnings will be "barely in the black" despite the prediction that 1980 will be the worst year for housing since World War II.

Yesterday the Department of Commerce said housing starts fell in May to a seasonally adjusted annual rate of 920,000 units, 49 percent below the May 1979 rate.

In Christian's view, conventional mortgage interest rates won't go below 11 percent, although he said he could see the administration exerting pressure to lower FHA-VA rates to 10 percent. As for the Federal Reserve's easing up on credit restrictions, Christian quipped, "I don't expect a return to easy money for several more months unles (President) Carter turns (Fed Chairman Paul) Volcker's cigar around in his mouth and tells him he can't get reelected otherwise."