Montgomery County officials, lawmakers and representatives of citizens groups, citing an alarming increase this year in alcohol and drug-related traffic fatalities in the county after several years of decline, unveiled an ambitious series of legislative proposals yesterday to strengthen the statewide dragnet for drunk drivers.

They also announced a holiday crackdown effort that will include at least one sobriety roadblock in each of Montgomery's five police districts and more police "saturation patrols" aimed at catching Christmas and New Year's merrymakers who "imbibe, then drive."

"This year there is special concern over entering the holiday season with alcohol-related fatalities having increased, according to county police, from five in 1983 to 18 in 1984," County Executive Charles W. Gilchrist said at a news conference. Prior to this year, alcohol-related deaths had decreased every year since 1980, when 30 such deaths were reported.

Police have made 3,300 drunk driving arrests in the county this year, an 11 percent increase over 1983, Capt. Max Whitehead said. According to a study released last spring by Montgomery Mothers Against Drunk Drivers, the average fine levied by county judges for driving while intoxicated was $185 out of a maximum penalty of $1,000. For the less serious offense of driving under the influence, the average fine was $135 out of a maximum penalty of $500.

Despite Montgomery County's image as a leader in efforts to stop drunk drivers, "it's time to quit patting ourselves on the back," warned John V. Moulden, alcohol program coordinator for the National Transportation Safety Board and chairman of Montgomery's Alcohol and Safety Committee. He said tough new legislative fixes are needed to plug lethal loopholes in state drunk driving laws. Maryland's efforts come on the heels of legislation that went into effect last summer in Virginia toughening that state's drunk driving laws.

Legislative proposals, to be shepherded through the Maryland Senate by state Sen. S. Frank Shore and through the House by Del. Jennie M. Forehand, both Montgomery Democrats, in the 1985 session of the General Assembly are:

A bill to lower to .10 percent from .13 percent the level of alcohol in the bloodstream for the charge of driving while intoxicated. "It's outrageous that Maryland is the only state that allows above a .10 percent blood level," Moulden said. "It's time to join the other 49." For the less serious offense of driving under the influence, Moulden said Maryland's legal level should be lowered to .07 percent from .10 percent.

* A bill to automatically send repeat offenders to jail for 48 hours.

* A bill, already enacted in 23 states, to allow the arresting police officer to take away a drunk driver's license on the spot.

* A bill to prohibit open alcoholic beverage containers in vehicles.

* A bill to reclassify vehicular manslaughter from a misdemeanor to a felony.