Stream Bug Monitoring (BIBI)

Benthic Index of Biotic Integrity (BIBI)
We monitor the health of freshwater streams by looking at what types of insects live on the stream bottom. This special group of insects are called "benthic macroinvertebrates" and include insects, crustaceans, worms, snails and clams. The type, number and diversity of bugs that live on the stream bottom can tell a lot about stream water quality. Stream macroinvertebrates are useful indicators of water quality, because they spend their lifecycle in a small area, they have a short life span and different species have different tolerances to water pollution. 

Insect samples are collected and sent to laboratories where the bugs are identified, grouped and counted. The bug population data is analyzed using a scoring system called the Benthic Index of Biological Integrity (BIBI). This produces a number ranging from 10 (very poor) to 50 (excellent), which describes stream health.  More information about the BIBI scoring system and access to benthic data from Pierce County and elsewhere around Puget Sound are available at Puget Sound Stream Benthos.
Contact Us

Carla Vincent
Water Quality Supervisor
Email me
Ph: (253) 798-2467

Public Works
2702 S. 42nd St.
Suite 201
Tacoma, WA 98409
Ph: (253) 798-2725