Baltimore Mayor William Donald Schaefer has proposed that the Maryland General Assembly authorize $15 million of improvements to Memorial Stadium in exchange for the Orioles and Colts signing six-year leases.

Schaefer also said Wednesday that if the Colts refused to sign such a lease, he would seek a separate $7.5 million bond authorization to make the improvements desired by the Orioles.

Edward Bennett Williams, owner of the Orioles, said, "I've had meetings with the mayor. He would dearly like to have a commitment from the Orioles and Colts for a multiyear agreement.

"Obviously, all the plans proposed up until now have been oriented to the Colts. The Colts are unwilling to give him a multiyear lease. We're in a position of watching and waiting."

Schaefer said Wednesday that Williams was amenable to signing a six-year lease.

Williams said, "We haven't gotten to that point of talking to the Stadium Authority."

The legislature approved a $22 million bond issue for stadium renovations in 1980 but required that both teams sign 15-year leases before the bonds could be sold.

The offer will expire June 30.

The Orioles' one-year lease on the stadium expired at the end of last season. The team began operating on a year-to-year basis in 1979 and negotiations for a new lease have not begun.

"We're expecting to do it anytime," said Larry Luchino, general counsel to the Orioles.

"The normal negotiations have gotten sidetracked by this legislative effort. We're eager to sit down and talk with the Park Board."