Shinglemill Creek is one of Vashon's major drainages. It has experienced a decline in aquatic invertebrate populations in the last seven years. photo by: Bianca Perla

This is one of the larger stonefly larvae found in northwest streams. photo courtesy of: Jeff Adams and the Xerces Society.

Monitoring stream invertebrate communities can tell us much about the health of our streams and the impacts they are experiencing so that we can better steward this valuable resource. photo by: Bianca Perla

Island Stream Invertebrate Survey (ISIS)

UPDATE: Special middle school and VHS student presentation to the Groundwater Protection Committee on Shinglemill Creek health will be held Monday November 18th at 6 PM at the Land Trust Building. All are welcome. 


Aquatic invertebrates residing in streams are connected to almost every aspect of the stream ecosystem. They are eaten by birds, fish, and mammals. They help salmon populations thrive. They deliver important functions to the stream ecosystem by aiding in nutrient cycling and decomposition of plant and animal debris. Many of these aquatic invertebrates are the larval form of what later become flying insects like mayflies, stoneflies, damselflies and mosquitoes which are eaten by a variety of animals including fish, bats, or migrating songbirds. 

King County has been taking invertebrate samples at 14 different sites on Vashon streams since 2005.  To access this data visit the Puget Sound Stream Benthos page.  

A preliminary look at the data shows that all 8 Vashon streams sampled have scored from very poor to fair condition. We have no good or excellent scoring creeks. Furthermore, four of the eight streams sampled have declined in condition from 2005-2012.  Why is this so? 

Vashon Nature Center LLC is working with the King County Groundwater Protection Committee to try to answer this question. 

Would you like to help us solve this mystery? We plan to use volunteers to collect invertebrates from Vashon streams starting in the fall of 2013 to supplement the long-term monitoring that King County has started and to start testing hypotheses about different influences on island stream health.

Email:  for more information or to participate in this program.

Reports and Data

Progress Presentation by Vashon Nature Center LLC to King County Groundwater Protection Commitee October 24, 2012. Download the powerpoint.

Groundwater Protection Committee's Liquid Assets Report Card. Download the pdf file

Final Report on Summary of Existing IBI data for Vashon 2005-2011. Download the pdf file