Slimy Leaves for Clean Streams: The Leaf Pack Experiment

How can a clump of in-stream slimy leaves provide the basis for stream ecology exploration? 

For years, stream ecologists have used slimy clumps of leaves called leaf packs, to assess the health of a stream. More recently, the scientists at Stroud Water Research Center collaborated with environmental educators to create the Leaf Pack Experiment and through this unique technique, trained teachers and citizen volunteers on how to use leaf packs to study the life in – and assess the health of – their local streams; using an onion bag!

The Leaf Pack Experiment is a research tool for non-scientists, directly demonstrating how disturbances on land impact life in streams and water quality. 

Leaf Pack promotes inquiry-based interdisciplinary watershed education and engages diverse audiences in:

  • conducting their own experiments,
  • gathering relevant ecological data,
  • exploring food webs,
  • learning classification skills,
  • using technology to share data,
  • comparing data with those of other communities and applying that information to solve local watershed problems.

Hundreds of teachers from all over the world – from New York City to the suburbs of Philadelphia to rural parts of Michigan as well as indigenous villages in Africa, Peru and Costa Rica - have used the Leaf Pack Experiment to identify the health of their local stream and to understand the story the stream is telling about how surrounding land use is affecting its waters. 

At the end of a leaf pack experiment, participants share their data on the Leaf Pack Network® website.  The Network is a rich web-based resource that provides access to data gathered by participating schools across the world, as well as information on macroinvertebrates, watershed research, riparian ecology, and water resources.   

Teachers in Colorado can also participate in this network by uploading their data and comparing results with a school monitoring the same stretch of stream, several miles upstream, or by comparing their data with a small stream monitored by citizens in Pucallpa, Peru.  

For more information about the Leaf Pack Experiment and the Leaf Pack Network® please visit:


Leaf Pack Network® is a project of Pennsylvania-based Stroud Water Research Center.

Leaf Pack Network®

Leaf Pack Network® is a project of Stroud Water Research Center, a Pennsylvania-based not-for-profit organization whose scientists and educators work to advance the knowledge and stewardship of freshwater systems through global research, education and restoration.



Leaf Pack Training in Colorado and the West

RFC Director of Community Outreach, Christina Medved, is the Leaf Pack Network® Ambassador for Colorado and neighboring states. For more information about this program or to schedule a workshop, please contact at or (970) 927-1290 ext. 103.

Contact Us

Roaring Fork Conservancy

PHONE: (970) 927-1290

PO Box 3349
Basalt, CO 81621

22800 Two Rivers Road
Basalt, CO 81621

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