A small group of citizens who are concerned that a three-mile sewer line down Paint Branch may destroy that trout stream's excellent water quality and lead to greater development in western Montgomery County took a hike last weekend to view firsthand the proposed path of the line.

Clad in jeans and boots, armed with bug spray and accompanied by 15 officials and consultants, about 10 citizens braved a path covered with poison ivy and thick brush in order to see for themselves what will happen to the county's only natural trout stream when the Paint Branch relief sewer is installed early next year.

They trudged through thick strands of honeysuckle, poison ivy and Virginia creeper alongside a rising wall, hundreds of feet high, formed by black locust, black birch, white oak, sycamore and yellow poplar trees. They crossed Paint Branch seven times - just as the proposed sewer line will - and saw their reflections in its sparkling water.

The occasion was a "walk-through" sponsored by the Washington Suburban Sanitary Commission (WSSC) as a means to familiarize citizens with the way engineers plan to install the line, not to resolve questions of whether the line should be built at all. The agency has conducted walk-throughs for four years as a means of determing citizen concerns so they can be accommodated before the project is already built.

The proposed $1.3-million Paint Branch relief sewer has been approved by the WSSC and the county councils of Montgomery County and Prince George's County, which it traverses as its farthest downstream end. The line is to run parallel to an existing 17-year-old sewer line, now near its capacity, from slightly north of Columbia Pike Road (Route 29) to the Hollywood Branch, just over the Montgomery-Prince George's border.

Only the walk-through last weekend only two citizens, representing trout fishing and conservation groups, were openly and flatly opposed to the project. Commissioner Vera Berkman of the sanitary commission, who went on the hike, praised the citizens in general for being open-minded.

Opposition to the project was present, however, even if it was not forcefully stated. Concern for conservation and fear of encouraging greater development in the Paint Branch watershed, now a largely rural area of western Montgomery County, were the dual concerns.

Trout fisherman Frank Clark simply said the sewer line installation would "eradicate" the stream. Paint Branch is the only state-designated Class III stream in Montgomery County, meaning that trout can live and propigate naturally in it. Other streams have been stocked with trout from time to time, but the Paint Branch trout population dates back to an initial stocking in the 1920s.

Standing under the Route 29 bridge over Paint Branch, Clark pointed to the stream's 40- to 50 foot width and the steep green gorge formed by the trees on each side.

"Visualize a bulldozer going down there," he said. "You can't make this stream a construction corridor without having a detrimental effect on the stream life and the water quality.

There's a strong possibility that the trout will be eliminated for good."

Clark claims the sewer line down Paint Branch is the least desirable of many possible alternatives. WSSC officials counter that it is the most cost-effective alternative. Other plans involve leasing large amounts of land for land treatment of sewage or employing a pumping station and pressure line rather than a gravity-flow system.

Most of the citizens who went on the walk-through seemed more concerned that the new sewer line would lead to increased development.

"We are thinking about whether these new sewers are oversized or not," said Marcella Petree of the Montgomery County Civic Federation. "Usually they're made twice as big as they need to be. This is understandable - the engineers try to build in safety factors. But eventually their size is used to control development."

"paint Branch is a real treasure," said Joseph Slunt of the White Oak Area Civic Coalition. "They're probably doing as much as they can to protect the stream. But my concern is the long-range effect of having the sewer capacity and encouraging development."

A consultant's report, while supporting the WSSC's plan, indicated that the concerns both of the trout fishermen and those who think the building of the line will increase development in the area are valid.

The report said installtion of the line will eliminate some species of fish that now live in the stream, while it is "unpredictable" whether the brown trout population would survive. However, it stressed that the long-term suburbanization of the watershed would do more to harm the stream than the one-time sewer line installation.

Brian Price, the consultant, said the project was the best alternative despite the tradeoffs of temporary stream degradation and development pressures. He said that the planned development that could take place if the sewer line is put in would be more desirable than the limited and random development that would occur in the general area if the line is not installed.

Glenn Furtado, water and sewer design sectio head for the WSSC, said he hoped that work on the sewer line would begin in early January, 1978. Construction is expected to take 1 1/2 years and cost the counties $158,000. The state will pck up another $158.000 and the federal government the remaining $991,000.