Puget Sound Stream Benthos

Analyzing Stream Health

This site analyzes benthic macro­invertebrate community structure to determine the ecological health of streams.  Participating agencies use this site to manage, analyze and share data from their ongoing stream monitoring programs.

Picture of Stone FlyBenthic macro­invertebrates, also known as stream bugs, are animals that can be seen with the naked eye, do not have backbones and live in the stream benthos—in or near the streambed.  They include insects, crustaceans, worms, snails, clams, etc.

Benthic macro­invertebrates are monitored because they are good indicators of the biological health of stream systems and play a crucial role in the stream ecosystem.

Plotting Biotic Integrity

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The B-IBI Scoring System

We use the Benthic Index of Biotic Integrity (B-IBI) scoring system to determine stream health. Since the B-IBI is a standardized scoring system, it can be used to compare and rank the health of different streams.

B-IBI has several variants, and we will support many of them over time.  Currently, we are using Puget Sound Lowlands B-IBI. This site allows you to filter the scores by a variety of parameters and then

Regional Puget Sound B-IBI Projects

King County worked with regional partners on two Puget Sound B-IBI projects. For more information and to view products related to these efforts please go to:
  1. B-IBI Recalibration. 2010-2014.
    This project enhanced benthic macroinvertebrate monitoring tools for the Puget Sound region.
  2. Restoration Priorities. 2013-2015.
    This project developed a framework for identifying sites and strategies to protect watersheds with "excellent" B-IBI scores or restore watersheds with "fair" B-IBI scores.