The deflector consists of logs making a triangle shape

Under the cover of trees at the back of a cow pasture on a quiet country road, two dozen youths are pushing large rocks and logs into a stream.

It might sound like vandalism, an oddly coordinated teenage rebellion.

But look a little closer and you'll see it's just the opposite.

The young people are students at the Lancaster County Youth Conservation School.

They're building a sediment trap to improve Middle Creek's water quality.

The Clay Township project will create a log-faced stone deflector, said Karl Lutz, stream habitat section chief at the Pennsylvania Fish and Boat Commission.

The deflector consists of logs making a triangle shape. One edge runs along the bank, while the other two sides jut into the stream. The structure is then filled with rocks.

The device "creates a pattern of circular water" that forces the water slightly uphill, slows it down and traps silt, Lutz said.

While Middle Creek already is fairly healthy, the device will be another small step in cleaning up the Chesapeake Bay watershed.

The deflector also provides a permanent habitat for fish, Lutz said.

Caleb Greiner and Jared Groff, two friends from Manheim participating in the school, started the day by helping haul a log into the creek.

They stood on either side of the stout trunk and carried it with logging tongs and help from another pair of students.

After the three logs, ranging from 5 to 8 feet in length, were in place, the students, mostly the boys, took turns hammering rebar pins into holes that adult volunteers had drilled in the wood.

They shouted encouragement when their classmates hit the pin and offered collective groans when the sledgehammer glanced off the bark or splashed the water instead.

After the logs were firmly secured,aluminum foil tape, the construction team traded tasks with another group of students. They'd been upstream learning about stream life.

That group took a turn filling the log triangle with rocks.

A team from Flyway Excavating of Lititz, which donated all the materials for the project, transported the rocks with a skidloader from a pile in the field to the stream bank.

The youths then rolled the rocks, which were up to a foot long, into place under the direction of camp counselors and Flyway workers.

Meanwhile, the log-placing team was now scouring the creek for macroinvertebrates.

Those are spineless animals that are large enough to be seen without a microscope, said Hannah Brubach, an intern with the Department of Conservation and Natural Resources.

These critters are susceptible to pollution, so finding them in a stream is a good indicator of stream health, she said.

Crayfish, which the students found in abundance, are an exception to that rule.

They can tolerate almost any conditions and are "not a good indicator," she said.

Caleb Greiner's group netted a more interesting find, a several-inch-long hellgrammite.

Brubach estimated the centipedelike invertebrate was 4 or 5 years old.

The group also found a clam, which Brubach said is an invasive species, and a minnow.

Log-faced stone deflectors can be built only with a permit from the Department of Environmental Protection, Lutz said.

Robert and Ruth Fox, the owners of Clay Farm, where the project took place, have welcomed the students for several years.

In return, they end up with a new stream-control fixture basically every year.

The Foxes, whom the Conservation District honored last year with an Outstanding Cooperator Award, have implemented numerous conservation practices on their farm.

On this sunny day, the students benefited from one of those installations — a riparian buffer.

It's a stand of trees along a creek that controls runoff and shades the water from excessive sun.

The stream water-quality project was only a small part of the Youth Conservation School experience.

The students lived for the week at the Northern Lancaster County Game and Fish Protective Association in Denver.

The club shuts down for a week each summer to accommodate the tenting students.

Lancaster-area sportsmen's clubs sponsor the county students who attend, covering almost their entire tuition.
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