Theory May Get at Root of Water Quality

The best way to reduce water pollution may not be by targeting factories and sewage plants, some scientists believe, but by planting trees along the banks of small streams.

If the theory becomes public policy, it could dramatically change landscapes where trees have been cleared away for hundreds of years.

The Stroud Water Research Center, a field station of the Academy of Natural Sciences in Philadelphia, has a grant from the National Science Foundation and the Environmental Protection Agency to examine 20 streams in Pennsylvania and Maryland over the next three years.

The concept of forest buffers for streams was developed a decade ago but is not universally accepted.

According to the center’s director, Bernard W. Sweeney, the lack of trees changes the shape and character of stream beds.

For 10,000 years before European settlement, most of the land in Eastern states was forest, Sweeney said. Cutting down those trees changed the creeks and rivers.

“The resulting pastures and meadows made the streams narrow and deep,” he said. “Streams with forested banks have channels that are two to four times wider.”

Think of a stream in the forest, Sweeney said. It’s shallow, wide and cold. The water runs fast over a rocky bottom.

Now think of a stream surrounded by cleared pastures. It’s narrow and deep. The water is not as clear, and it’s warmer. The banks are mud flats edged by grass, which traps sediment in its roots. As sod encroaches on the sides of the creek, it becomes narrower.

“By restoring the width, you increase the capacity to grow fish, process pollutants--in short, sustain life,” he said.

The central question of the study is how much is this capacity increased by reforestation.

In recent years, the focus on cleaning up water pollution has shifted to runoff from such areas as fields and lawns.

Living things in small streams feed on the material washed in from the land. But if the streams don’t have enough life, the nutrients end up in such places as the Chesapeake Bay, overwhelming the water life.

Dave Welsch, a watershed specialist for the U.S. Forest Service in Durham, N.H., sees reforestation as a cheap way to control pollution.

“There are other ways to treat runoff,” he said. “You could collect it and run it through some sort of filter, but it would be expensive.”

Forest buffer zones, Welsch said, remove 80% of the sediment and chemicals that scientist believe should come out of small streams.

Stroud researchers will examine where streams run through wooded areas first and then in open space and streams that go from fields into stands of trees.

They will take monthly measurements of stream size, flow, temperature, chemistry and life forms--from algae to the biggest fish.

The concept of protecting streams makes sense to Joe Dudick, a spokesman for the Pennsylvania Rural Development Council.

“The planting of vegetation is something farmers and other landowners would consider,” Dudick said. But, he said, “farmers, like everybody, don’t like somebody coming in and imposing conditions on them.”

According to Sweeney, there is general agreement about creating buffer zones around small streams.

“The question now is: Do you plant hay or do you plant trees?” he said. A farmer can cut the hay and get some benefit from it, he said, but he might have to wait 20 years to make any money from a stand of trees.

Part of the project includes work by social scientists at Penn State University and the University of Delaware. They will conduct surveys and focus groups to learn what issues are important to landowners and what would be needed to get them to voluntarily convert stream-side lawns or pastures to forest.

Some conversion already is occurring, according to Rick Cooksey, a forest resource planner at the U.S. Forest Service in Annapolis, Md.

An extensive project in Harford County, Md., is on track to completely reforest the Little Gunpowder River, a trout stream, Cooksey said. Another, on the Conodoguinet Creek in Pennsylvania, uses citizen volunteers to restore the forest and monitor it.

“In many restoration projects, we have heard from private landowners who enjoy the benefits of the new forest area,” Cooksey said.