Saturday's Washington Post reported that two groups are interested in building a domed stadium midway between Washington and Baltimore. The stadium would house the Baltimore Colts and Orioles as well as the Washington Redskins.

The report immediately revived interest in major league baseball for the Washington area. Some baseball fans spoke of having the Orioles available within reasonable driving distance. But others thought a new attempt should be made to bring "a team of Washington's own" to RFK Stadium.

Both possibilities are unrealistic. Let's look at some inescapable facts that many sports fans overlook.

It cost $32 million to build the Houston Astrodome in 1965. By 1975, inflation had driven up building costs and the New Orleans Superdome cost $163 million. You can make your own estimate as to what it would cost to build a domed stadium in the Washington-Baltimore area in 1985. Surely it would be more than $200 million.

If the stadium were built with public money, it might be financed with tax-exempt bonds. If interest rates fall to 6 percent on revenue bonds (they now run more than double that figure), the interest on $200 million would be $12 million a year. The stadium would also have to generate income for paying back the loan itself -- for example, $5 million a year for 40 years. f

The stadium project would therefore begin its existence with a need to take in $17 million a year. If the stadium made money, interest costs would go down as the loan was paid off. If the stadium lost money, the debt, and interest costs, would rise.

If the Redskins and Colts both sold out a 74,000-seat stadium for eight league games and two exhibitions, they would sell 1,480,000 tickets a year. If the Orioles drew 2 million, ticket sales would total 3,480,000 annually. But there is no assurance the Redskins would sell out a 74,000-seat stadium for 10 games a year; the Colts' home attendance last year was 333,208, not 740,000; and the Orioles have never drawn 2 million.

But let's be optimistic and assume that the three teams would, together, sell 3 million tickets a year. Even so, each ticket would have to bear a surcharge of $5.66 for stadium rent alone -- quite apart from each team's normal need to recover player salaries, travel expenses and other overhead costs such as maintenance and lighting.

Thus far, we have been discussing a stadium built with tax-exempt bonds that bear a low interest rate. If private entrepreneurs built a domed stadium, the interest rate might be double those I projected.

Compare these "rental" costs to the favorable leases that most major league baseball teams now enjoy. The District would be delighted to have a baseball tenant in RFK at an annual rental of $150,000 for the first million in attendance, or 15 cents per ticket.

A baseball team that can absorb a rental expense of 15 cents or even 25 cents in its $5 ticket might have to raise that ticket to $10 or $15 if it played in a newly built domed stadium. Do you think that might have an inhibiting effect on attendance?

Even an attempt to put a baseball team of our own into RFK would encounter major problems. For example:

The astronomical salaries that must now be paid to free agents have cooled the ardor of many potential backers of big league baseball.

Mayor Barry wants black participation in the ownership of any new baseball team that comes to RFK, but thus far no black capital has volunteered to come forward for such a risky venture.

Stricter tax regulations have diminished much of the depreciation allowance that once made professional sports a reasonable gamble for private entrepreneurs.

Baltimore can and will veto an American League team in Washington. National League owners do not want expansion, and even if you can find an existing NL team for sale at a rational price, you are not likely to get permission to move it to Washington. Keep in mind that the late Joseph B. Danzansky bought the San Diego Padres but found he couldn't get them out of San Diego.

Bowie Kuhn has taken a stand in favor of one team for the Washington-Baltimore area. Kuhn usually speaks for a majority of the owners.

My conclusion must therefore be that before you see major league baseball in Washington, or in the Washington suburbs, some monumental problems will have to be overcome.