Louisa Stevenson peeled Japanese beetles off a tree branch and then with a steady overhand pitch hurled them into the stream behind her farmhouse.
The reaction took a split second. The water splashed with a frenzy of fins.
She might have been a teen-ager idling away a pleasant day by her favorite swimming hole. But this determined woman, whose hands were still dirty from vegetable gardening, was making a point.
The East Branch of the Patapsco River is filled with fish. A stream that once was not so bountiful has come back.
Stream watchers aren't certain why the trout population has returned. But they suspect that the East Branch of the Patapsco, along with many other streams across the state, is reviving because of stream-stocking by Johnny Appleseeds, changes in farming practices and other pollution-control efforts in the Bay's watershed.
"People are cleaning up their act," said Robert A. Bachman, the Department of Natural Resources director of freshwater fisheries.
The clarity of the East Branch, in particular, is a vivid example of how intricately the use of the land and the water are linked, according to Thomas Gamper, a 34-year-old Baltimore architect and avid trout fisherman who has made a project of the stream.
The East Branch was never horribly polluted. Trout have been seen in portions of its tributaries, such as Aspen Run, for at least the past decade. Local fishing lore has it that a 26-inch trout was caught in Aspen Run in the 1970s.
But when a Department of Natural Resources biologist surveyed the main stem of the East Branch more than a decade ago, he came up with barely any fish at all.
The discovery that fish had returned to the stream began this spring when Thomas Gamper decided to find out just what shape the stream was in.
He and 40 other Trout Unlimited volunteers walked the East Branch, looking for signs of pollution and casting a fisherman's eye on the places trout like to hide.
Their work convinced the Department of Natural Resources to use an electric shocking technique that temporarily stuns fish and allows the scientists to count their numbers in the stream.
The result? They found lots of fish.
Fish of all sizes.
Fish of all ages.
Fish in every niche you might ex pect to find a fish.
For trout fishermen the fact that another stretch of babbling brook is cool and clean enough to harbor scores of brown trout is always welcome news.
But for Baltimore residents it means even more: clean water. Th Patapsco, skinny and shallow as it traces a veiny path through the Carroll County landscape, runs into Liberty Reservoir, one of three city and county drinking water sources.
"It was very impressive," said Brian Kaltrider, a local fisherman who was there to see the results of the department's work. "It is encouraging since trout need such clear, cool, clean water. . . . We have a very, very good source of water for the reservoir."
Because of the quality of the East Branch, the department has asked the Maryland Department of Environment to reclassify it to give it more protection. Despite the common perception that the streams of the state are being degraded, they actually appear to be improving, according to Mr. Bachman.
"Our official list of trout streams is going up, not down," he said, crediting the change to the land use and a "genuine awareness of people of the fragile nature of the environment."
Changes to the East Branch began with changes to the farmland that rolls over northeast Carroll County. In the past 10 to 15 years, older farmers who were less inclined to use innovative techniques have retired, said Stan Pennington, a conservation planner for the Carroll Soil Conservation District.
Younger men have begun renting those farms, using techniques that keep soil, fertilizer and pesticides on the land. They plant cover crops in the winter, use no-till farming and plant their crops in strips that conform to the contour of the land.
"I would imagine you don't see any muddy water coming off those fields," Mr. Pennington said.
"I think more farmers are aware of impacts on the environment than most people realize," said Edward Lippy, one of three brothers who work a family farming operation in that area of the county. "Farmers put their money where their mouths are."
There are some problems on the land. Development is encroaching. "As with any good trout stream, the source is the back of a shopping center," Mr. Gamper said sarcastically.
After it leaves its source, the stream goes through open fields where cows graze on the stream banks or lie in it. "Here at the headwaters, the stream should be cold, but instead it is being abused," Mr. Gamper said.
The stream winds its way through Mrs. Stevenson's land, stopping for a bit in deep pools with cooling natural springs, then racing along over small rocks. Once an avid fisherman, Mrs. Stevenson now comes here, particularly on a hot summer day, to watch the goings-on.
The preservation of this stream, she said, has been possible because the landowners have been vigilant. A decade ago, they helped shut down a local dump. And private landowners, who own all the stream banks, have protected the stream from zealous fishermen who would take home as many fish as they could catch.
Trout Unlimited's ethic calls for fishermen to release any fish they catch. Of the dozens of fish Mr. Kaltrider caught on the Patapsco last year, he said he kept only one.
"The temptation is to run back and catch them," Mr. Gamper said. But in fact, his reaction has been just the opposite. "Leave them alone. It took them a long time to get there."