When a complaint came in that Rock Creek was turning white, Gerry Evans sent an inspector from the Department of Environmental Protection to find the cause of the pollution and stop it. When several Montgomery County restaurant owners complained about having to shut down because of their dirty kitchens, Evans asked the county health department to have a supervisor check the health inspector's work. And when a political friend complained that he did not get a merit job, Evans phoned the friend and offered two others.

In a sixth floor office of the county office building in Rockville, Gerry Evans, Montgomery County Executive Charles W. Gilchrist's personal aide, does whatever his boss desires, and sometimes more.

"My job," says Evans, "is to keep the government responsive."

In the two years since Gilchrist took office and hired Evans, however, at least some council members and county officials have questioned whether the 24-year-old aide tends to be too zealous in carrying out his mandate. In their view, Evan's is too eager to please the county's various constituencies and the result is often trouble both for him and his boss.

Those questions -- as well as the more general issue of whether the county is being efficiently managed -- were raised again this week with the disclosure of tape recorded phone conversations showing that in February Evans had offered two merit jobs to Leonard I. Colodny, a political friend, in violation of county merit job laws.

Evans claims that he offered the jobs "just to get him [Colodny] off my back."

But to some County Council members, Evans' actions suggested that the Gilchrist administration is more worried about keeping its friends happy than about managing the government properly. And they also suggest that his frequent involvement in problems means that Gilchrist is not in control over the day-to-day management of the county government.

"Evans runs the goddamn government," grumbles one county official. "He makes the deals while Gilchrist is out cutting ribbons."

Evans, a graduate of Frostburg (Md.) State College, met Gilchrist about five years ago when Gilchrist was a state senator and Evans, an aide to another state senator, Victor Crawford. "I never met anybody like Charlie," said Evans in an interview several months ago. "He's so open and honest and has a great sense of humor."

As the aide most responsible for dealing with constituents, Evans has had the most contact with job seekers. Often, he is quite willing to help them out. It was Evans, for example, who suggested to the director of the department of Liquor Control that he hire Frank Orifici to be deputy director, a merit job.

Orifici is the nephew by marriage of Charles Buscher, Gilchrist's adviser on the department, and his appointment resulted in complaints that the merit system had been tampered with.

For several months before and after Orifici got his job, Evans and Gilchrist denied that either of them had had anything to do with Orifici's selection. But in September, the director of the department, Robert Passmore, told a group of reporters that Evans had phoned him and suggested he hire Orifici.

Gilchrist, who apparently is worried that Evans' taped job offers may come back to haunt him when he runs for reelection in 1982, this week announced that he was putting some reins on his young aide. "For my sake and his sake I am going to make it clear he is not going to be involved in this sort of thing again," Gilchrist said.

From now on, Evans said yesterday, he will not talk to job seekers about jobs that by law must be filled through the merit system, but simply will refer them to the county employment office.

His other duties will remain the same. He still will listen to citizen complaints and try to resolve them. He still will prepare Gilchrist's material when he speaks to students in the county schools. And he still will help make appointments to the county's nearly 50 citizen advisory panels.

While Evans does most of the communicating with constituents, Chief Administrative Officer Robert Wilson, the number two man in the county government, does most of the communicating with department heads and other county employes. "Wilson makes the trains run on time," said Evans. "He sees to it that Gilchrist's policies are implemented."

Like Evans, Wilson in a taped phone conversation asked Colodny if he was interested in a merit job but also mentioned that the county has a merit system.

Even his critics regard Wilson as a competent professional who has a sound working knowledge of county government. Before coming to Montgomery County, Wilson was the chief adminstrative officer in Prince George's County when Winfield Kelly was county executive. He also was the county executive in Fairfax and an administrative assistant in Arlington.

As the so-called Liquorgate controversy has unfolded, Wilson has tried his best to protect the county government from unfavorable publicity.

When one reporter, for example, asked Wilson for a memo that had been issued by Colodny, who was then a consultant to the county, Wilson offered the reporter one printed page. The report had been described as consisting of 11 pages.

When the reporter asked for the remainder of the memo, Wilson offered another two pages.

Finally, when the reporter asked for all 11 pages, Wilson produced it.

"It's my job to keep these things from you and your job to find them," he said.

Around the offices of the county government, Wilson is commonly regarded as more professional, but less likable, then Evans. But even Wilson's professionalism has come into question because of the tapes.

Yesterday, the County Council asked Wilson to provide assurances he had not misused the merit system. Earlier this week, Council Member Esther Gelman said she would ask the council to consider removing Wilson from his post if the council finds that he did, indeed, offer Colodny a merit job.