D.C. Mayor Marion Barry announced a tentative contract agreement yesterday that would provide a 9 percent base pay increase over three years to 17,000 city employees.

In addition to a pay increase of 3 percent in each of the three years of the contract, employees would receive a 2 percent bonus for fiscal 1989 and a possible additional increase of 2 percent in 1990 if the consumer price index rises by 5 percent that year.

The agreement covers blue- and white-collar workers, including correctional officers and clerical workers. Previously an agreement was reached between the city and the police, but the Disrict's negotiations with firefighters are still continuing.

The tentative agreement announced yesterday, which must be ratified by the unions and approved by the D.C. Council, also would require that the city and its employees negotiate a new "pay-for-performance" evaluation plan by 1990. The plan would be put into effect no later than fiscal 1991.

Mark H. Levitt, acting director of the city's Office of Labor Relations, said the pay-for-performance evaluation plan will include specific performance standards by which workers must be measured.

He said that past contracts contained merit increase provisions tied to satisfactory performance but, in effect, resulted in automatic increases that totaled about $9 million during the previous three-year contract because employees rarely got unsatisfactory evaluations.

"We wanted to develop a new pay plan to give incentives," said Levitt. "It could mean more money for people who do well or if people don't do as well on an evaluation, they won't get a merit step. It could save the city money and increase performance."

Because the tentative contract includes the majority of the city's unionized employees, Levitt said it will be difficult to develop a pay-for-performance system for the variety of jobs involved. He said the city will seek help from experts.

Union officials could not be reached for comment.

Other key provisions of the proposed agreement include compensatory time off for essential employees who work when the rest of the government is shut down and time-and-a-half pay for all overtime and time-and-a-half credit for compensatory time.

The tentative agreement was reached after the unions' negotiating team declared an impasse in October. According to a statement issued by Barry's office, Barry intervened in the negotiations last week to break a stalemate on final items.

"I am pleased that we have satisfactorily reached a tentative accord that will help set the pay rates for other District employees and continue the same pattern of increases reached with the Fraternal Order of Police in October," Barry said in a statement announcing the agreement.

The unions involved in negotiating the proposed contract were the American Federation of State, County and Municipal Employees; American Federation of Government Employees; International Brotherhood of Teamsters; International Brotherhood of Police Officers/National Association of Government Employees; the Communications Workers of America, and the Laborers' International Union of North America.