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Volume 2, Number 2
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Margaret Palmer kneeling in the Paint Branch Creek
Knee-deep in Paint Branch Creek, Margaret Palmer tracks a stream ecosystem threatened by heavy development in the watershed. Paint Branch passes right through Palmer's academic home on the College Park campus of the University of Maryland, which recently signed an agreement to help protect the urban stream.

An Ecologist on the Anacostia Watershed

By John R. Wennersten

Stepping into the fast-moving waters of Paint Branch Creek, Margaret Palmer lifts a stone and turns it to the light. On the bottom she spots a small brown bump of pebble and sand - a caddis fly case. She points out that while the caddis fly's winged life lasts for only a few days, its waterborne larvae can live from six months to two years, often beneath rocks and stones. As well as these cases, the larvae also spin silky nets.

"Some riffles," she says, "can be virtually covered with these filmy nets." Palmer has learned that the nets actually cause micro-turbulence in the stream, creating tiny eddies that help to entrain food - a phenomenon scientists have witnessed in marine organisms as well. According to Palmer, the larvae actually function as suspension feeders, much like oysters in the Chesapeake Bay, potentially helping to clear the water. A paper in the journal Nature by Palmer and her colleagues further describes how these ecological processes work. Describing precisely how human beings affect a watershed like that of the Anacostia, on the other hand, is proving a more daunting task.

As a watershed ecologist, one might say that Palmer has been swimming upstream a long time. For the past fifteen years her work as a biology professor at the University of Maryland, College Park, has centered on solving problems of streams and watershed tributaries in metropolitan areas.

This is a tough task but Palmer, an avid angler and outdoorswoman, maintains a realistic perspective. By focusing on the upper streams of the Anacostia, Palmer has worked with a team of scientists to provide well-grounded research-based models that will, she says, provide policy makers and managers with projections of future environmental impacts, assuming different rates of population growth, shifts in technology and changes in the regulatory environment.

Often, she says, those who work on watersheds employ scientific models based on the historical hydrology of streams and tributaries. But Palmer argues that there is little chance that we can restore the hydrology of a watershed to its pristine state. We need to be looking at the watershed as a "process" in terms of nutrients and contaminants, she says, while at the same time factoring in the consequences of public policies.

It is hard to help rebuild a watershed when people use what her economist colleagues call "hedonic property models" - the pursuit of maximum residential space with little thought of long-range consequences. But like many other variables, property development has to get factored into the scientific research equation, she argues. "To work effectively in the Anacostia and other urbanized watersheds," says Palmer, "we are going to need intensive collaboration among environmental professionals from diverse fields."

A caddis fly case on a stone from the creek
Hidden on a stone's dark underside, a caddis fly case tells the story of a stream's health. During rainy periods, heavy flow from paved surfaces and storm drains can flush out stream life, which may require weeks to recover.

While Palmer has worked on rivers and streams throughout the U.S., Paint Branch Creek has a special significance for her, since it runs right through the College Park campus. In fact, the University of Maryland has recently signed an agreement with the Anacostia Watershed Restoration Committee in an effort to improve its stewardship of the river's tributaries. The Agreement notes that the campus is "prominently located at the center of the Anacostia watershed," and many agree that with large areas of ongoing construction on campus, strong environmental stewardship on the part of the University becomes imperative.

Palmer and her colleagues have worked directly with land planners and environmentalists in the watershed - and pored over a host of variables from insect life to nutrients to the more difficult analysis of demographics, water flow and public conservation policy. For example, along with University of Maryland faculty members Nancy Bockstael, an economist, and Glenn Moglen, an engineer, as well as the University of Delaware's James Pizzuto, Palmer and her team have worked with Montgomery County's Cameron Wiegand and Keith Van Ness to map the evolution over time of four watersheds in Maryland.

Using aerial photography from the Maryland Geological Survey and ancillary tax data, the research team developed a method for modeling land use change at annual intervals. These models, Palmer says, have very high spatial resolution, so they can model changes in peak discharge as a function of location within the watershed. According to Palmer, this work has shown that relying on data from stream gauges alone may not necessarily reflect the conditions at small scales within the watershed. This could be especially important, Palmer and her colleagues point out, when measuring total maximum daily loads (TMDLs) of pollutants, where measurements at finer scales may be key.

They are hoping that, with adequate support, they can carry on this spatially explicit work, tightly integrating hydrological and ecological models in order to better predict how changes in land use will affect the health of streams and their watersheds.

"Margaret's work has been invaluable to us," says Cameron Wiegand of Palmer's collaborative efforts. "She and her team of water scientists from all over the country were able to conduct important nitrogen studies and other biomonitoring. She gave us important data that we could use in our restoration work. It shows that collaboration with scientists in stream restoration work really pays off."

"We can have a much better Anacostia," urges Margaret Palmer. She points to a successful case study in Montgomery County, which involved placing a by-pass pipe that redirected stormwater from a subdivision surrounding the tributary. The pipe eliminated a thermal barrier to trout entering the stream by keeping the water cool and by reducing peak flows during storms. Decreasing water temperatures by less than one degree allowed young trout to flourish in water that once was uninhabitable.

It all begins with small improvements in the streams of the upper watershed, she says. "This kind of local restoration work shows that we can have a watershed that is clean and cool enough for juvenile and adult trout to thrive. We all benefit from that in the long run."

For a description of the National River Restoration Science Synthesis Project, visit the web at www.amrivers.org/feature/riverrestoration.htm.

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