When John G. Milliken said he would emphasize recreation and the outdoors during his tenure this year as Arlington County Board chairman, it seemed a politically benign proposal.

However, the centerpiece of Milliken's recreation program, a proposal to stock Four Mile Run with trout so that residents may fish there, has drawn protests from some residents.

Although many residents have expressed enthusiasm for the idea, some have questioned whether such a project merits county attention or financing, and whether the water in the south Arlington stream is safe for the fish.

Plans call for stocking the stream with 2,000 rainbow trout shortly before March 19, the opening day of the newly created Four Mile Run fishing season. Another 2,000 fish would be added in April.

The water has been tested and is safe, said Steve Klemm, a fisheries specialist overseeing the project for the county. He said that rising water temperatures during the summer would make it difficult for the fish to live then, but he said most of the fish would have been caught by that time. Stocking the stream would cost the county about $6,000.

The issue has taken on a partisan tone. At a meeting of the Arlington Republican Committee last week, a resolution was passed calling the fishing proposal "unusual, cruel treatment for trout."

"From what I've seen of Four Mile Run, I would find it hard to believe that it's an ideal habitat for a trout," said James B. Robinson, a party vice chairman. "There's not that much water."

Dorothy Grotos, a former county board member and sponsor of the resolution, said storm runoff often carries grease and pesticides into Four Mile Run.

Some residents living near Bluemont Park, one of the designated fishing sites, are worried that the program would bring hundreds of fishermen to their neighborhood at a time when they are trying to reduce traffic and parking problems.

The residents recently asked county officials to move the park entrance from a side street to a main street to better handle the increased traffic.

"What they do in response is to think up another nice, but unnecessary, activity that will increase the traffic in the area," said Stephen P. Sapp, cochairman of the neighborhood's traffic committee. He added that he had no objection to the fishing program itself. "It's just the traffic."

County park officials said they fear that such debate will overshadow what they hope will be the opening of an annual fishing season that would showcase the cleanliness of Arlington streams such as Four Mile Run.

The program has received hundreds of inquiries, including many from people outside Arlington who hope to participate, officials said.

"What's nice is that people are not only interested in fishing, they want to help clean up," Klemm said. About 200 people have volunteered to clear trash and debris from the banks of the stream March 5. Other volunteers will work March 12 to create favorable conditions for the fish, such as areas of bubbling water, which would help increase the water's oxygen content.

Longtime Arlington resident Laurel L. Troup said she remembers when her sons, now grown, used to play in the stream. Troup is organizing a group of senior citizens to help with the cleanup.

"Children will especially benefit from the program. Parents often have no energy to take kids away to do things like go fishing," said Troup, who plans to bring her two grandsons to opening day.

In response to questions about parking, traffic and safety, county park operation supervisor Stan G. Ernst said there would be extra personnel on hand opening day to direct traffic and patrol parking areas. He said he expects that the number of fishermen will decrease greatly after opening day.

In early January, when Milliken proposed making open space and recreation his top priority for the year, some residents wrote letters to him saying that county problems such as housing shortages and the lack of adequate programs for the mentally ill should receive more attention.

Milliken has responded with long letters listing county efforts to meet such needs. He said his emphasis on recreation is meant to bring attention to programs that have been ignored in the past. "People will come to understand it doesn't take away from other priorities," he said.