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Streams of Science

EPA scientists use a unique Experimental Stream Facility to explore the health of stream ecosystems and watersheds.

Researchers in the Experimental Stream Facility

To better understand the importance of small-stream ecosystems and the dangers posed by pollutants, EPA scientists are conducting research at a unique, state-of-the-art laboratory: the Experimental Stream Facility (ESF).  The facility, located in Milford, Ohio, allows researchers to bring natural stream water indoors where they can conduct highly-controlled experiments.
The maintenance and protection of watersheds—the natural land areas that drain to common waterways—is vital to the protection of ecosystems and human health.  Watersheds supply drinking water, sustain life, and provide means for recreation.  While small-stream ecosystems comprise around 90% of the river miles in the United States and an even greater percentage of the linear drainage footage in any watershed, their overall importance to water quality is not yet well understood.

Stream ecosystems are largely overlooked in watershed management and left unregulated.  As a result, they are often replaced in land development projects with culverts, storm sewers, or lined ditches, eliminating their potential to play a role in maintaining water quality.

“You can think of small stream systems as your blood vessels carrying all these things coming from the landscape into larger water bodies, but we don’t really factor them in when we are doing watershed modeling calculations,” explains Christopher T. Nietch, Ph.D., a systems ecologist and lead scientist at the facility.

The facility combines the advantages of a controlled laboratory setting with the natural variability of field studies.  In a natural stream, assessing how individual pollutants and other stressors affect the ecosystem is difficult due to the various pollutants in the environment and other uncontrollable variables.  The technology at ESF, however, enables precise manipulation of variables like light intensity, stream length, water source, contaminant dose, and flow rate.  Therefore, the effects of contaminants can be studied and interpreted in a more conclusive way.

Scientists at the facility are developing novel methods for detecting changes in water quality. For instance, clam opening and closing behavior is monitored in tanks at the end of the stream channels (or “mesocosms”) and can signal the presence of environmental stressors before traditional warning signs, such as decline in algae growth, occur.  This type of monitoring has the potential to serve as an early warning system for contaminant spills and diminishing water quality.

Technology in the ESF continuously monitors water quality and characteristics as well as climate conditions both in the facility and in the nearby local streams.  “We’ve spent a great deal of time trying to ensure realism in our studies,” Nietch stated,  “and we spend a lot of time doing field work in real streams taking real measurements that we then use to guide experiments inside the lab.” 

The studies conducted at ESF are designed to obtain quantifiable data on the relative importance of small-stream ecosystems to watershed management.  They also test how different contaminants affect aquatic organisms and ecosystems in order to determine which pollutants are the most important to regulate.  This unique and advanced facility is amassing data that is very relevant to environmental decision making and to the future of watershed management.

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