Maryland Gov. Harry Hughes signed into law today some of the most significant legislation approved by the General Assembly during its 1986 session, including measures making seat belt use mandatory, severely restricting development on the Chesapeake Bay shores and overhauling regulations governing savings and loan associations.

The laws go into effect July 1.

Coming precisely a year after a run on deposits at Old Court Savings & Loan of Baltimore sparked a crisis that spread quickly to other state-insured thrifts, one of the new laws increases the state's power to inspect and subpoena thrifts' records and to punish those guilty of insider deals and certain real estate transactions.

Hughes described the legislation as "an effort to say that what happened in the past will never happen again in Maryland."

At one of two signing ceremonies today, Hughes and other politicians also hailed the package of Chesapeake Bay critical areas bills as "historic." Under the new critical areas laws, designed to curb pollution of the giant estuary, the use of valuable shoreline property by builders, farmers and timber-cutters is sharply restricted within 1,000 feet of the bay and its tributaries.

The new regulations governing the bay have become a campaign battleground for the two leading Democratic gubernatorial candidates, Baltimore Mayor William Donald Schaefer and Attorney General Stephen H. Sachs. Schaefer stirred a controversy when he said last month that some of the new regulations should be weakened within two years, a position he has since modified after receiving criticism from environmental groups.

Hughes also signed into law a measure that strips the Burning Tree Club of Bethesda of the $186,000-a-year tax break it receives under an open-land preservation program, unless it admits women.

The signing of a bill making seat belts mandatory for drivers and front-seat passengers marked the end of a 14-year effort by seat belt proponents and made Maryland the 21st state to make seat belt use compulsory. The law calls for a $20 fine for passengers failing to buckle up but says they cannot be cited unless stopped for another offense.

"It seems like it was a long time, but good things take a long time," said Audrey Hunt, treasurer of Women Highway Safety Leaders, which lobbied for the law. According to state police studies, 297 of the 740 people killed on Maryland roads last year could have been saved had they been wearing seatbelts.

Another package of new laws expands the power of the Montgomery County executive in the controversial area of development.The executive now will have veto power over many land-use plans and will appoint two members of the County Planning Commission, previously appointed by the County Council. The bills represent "the most significant legislation" affecting the structure of county government passed in many years, County Executive Charles W. Gilchrist said.

Another newly signed law forbids auto dealerships from putting advertising logos on cars unless the buyer agrees.

One less-publicized bill to cross the governor's desk today was a resolution on behalf of Oden Lewis, a deputy sheriff from Dorchester County. The resolution, which Hughes signed, requests that the Department of Natural Resources "act in a sporting manner" and give Lewis a $1,000 prize for catching a tagged trout as part of a state fishing contest. Lewis, 52, caught the fish on the Honga River last May but a dispute arose over whether the fish had been released long enough to qualify Lewis for a prize. Until now, Lewis had only been able to collect $200 in consolation prize money -- and the mounted fish.