Faced with shrinking budgets and increased demands for service, police agencies in the Washington area are cracking down on excessive false alarms by imposing fines.

Montgomery County Police Chief Donald E. Brooks, citing a steady climb in residential false alarms, announced plans yesterday to fine homeowners $30 for each false alarm over three a month or eight a year. In addition, county police intend to file misdemeanor charges, punishable by $500 fines or 90-day jail terms, against homeowners who deliberately activate alarms to assess police response times, he said.

"The false alarm issue is something crying out for a solution," Brooks said at a news conference. Calling the new fines a "radical departure" for the suburban police agency, Brooks said the department is overburdened with responses to alarm calls, 97 percent of which prove to be false.

Responding to false alarms drains resources of police departments and costs hundreds of thousands of dollars, police officials said.

"It's an unnecessary use of service by a small number of people," said Fairfax police Lt. Dana Libby. In January, Fairfax plans to impose fines ranging from $20 to $150 against merchants and homeowners in hopes of recouping some of the cost of responding to false alarms, he said. The fines begin with the third false alarm.

Libby said it cost Fairfax police $1.3 million to respond to nearly 37,400 false alarms last year. Seven locations accounted for more than 100 false alarms, and one location had 343 alarm calls, he said.

In Montgomery County, the partial cost of false alarm calls, based on officer salaries and vehicle expenses, was $800,000 last year, said Officer Gary Rademaker. Between 5 and 10 percent of the county's 38,000 false alarm reports last year came from repeat offenders, Rademaker said.

Area police agencies said false alarms account for a growing percentage of calls for service. In Montgomery County, 15.5 percent of service calls involved false alarms; in Fairfax County, 14.7 percent of service calls were for false alarms.

In about two months, the District of Columbia police force, which handled about 70,000 alarm calls last year, will begin imposing fines of $10 to $60 for false alarms exceeding eight a year at a business or home, said spokesman Daniel Straub.

Police agencies in other suburban Maryland jurisdictions, including Anne Arundel, Prince George's and Howard counties, have instituted or intend to implement penalties for excessive false alarms, officials said.

Brooks said Montgomery police hope the new policy will prompt homeowners to repair defective alarms or install better systems. Police estimate there are 15,000 residential alarms in the county.

Montgomery police plan a 60-day grace period starting Nov. 1 to notify the worst violators of the new enforcement policy, Rademaker said. Police will start writing citations Jan. 1, he said.

Commercial alarm owners in Montgomery are not affected by the new policy, Rademaker said. The county Office of Consumer Affairs has fined merchants for excessive alarm calls since 1984, he said.

Libby said false alarms can be potentially dangerous for police officers who have a tendency to become complacent. "If an officer goes to 200 false alarms, and then receives a call that's more serious, the potential for danger is much higher," he said.