What is bioassessment?
The Morro Bay National Estuary Program has conducted spring bioassessment surveys in the watershed since 2002. This data helps us understand creek health and how conditions are changing over time. The Estuary Program uses standardized protocols from the California Water Boards and the Surface Water Ambient Monitoring Program (SWAMP). Data is shared with partner organizations and the public through the California Environmental Data Exchange Network (CEDEN).
The bioassessment monitoring effort has two main field components. We collect benthic macroinvertebrates, which are bottom-dwelling animals visible to the naked eye that lack a backbone. These include creatures such as stoneflies, dragonflies, and aquatic snails. We also collect habitat measurements such as whether or not trees shade the creek to keep the water cool. This information gives us a good idea of the quality of the water and the habitat, not only for macroinvertebrates but also for the fish that feed on them.
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Related Blogs

Top Blogs of 2025: Happy New Year from the Estuary Program

November 2025 Field Updates: Assessing Creek Health with 2025 Bioassessment Results

May 2025 Field Updates: Reflections from a Tech’s First Season of Bioassessment

How Healthy are Our Creeks? Results from 2024 Bioassessment Monitoring

July 2024 Field Updates: Highlights from Spring Bioassessment

This project is made possible by the Harold J. Miossi Charitable Trust. Their support has been key to long-term bioassessment data collection, and we thank them for their generous contributions. For more information about the Trust, visit: www.miossicharitabletrust.org.