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. 

Volunteering for bioassessment

Each year, we invite participants from the community to support staff with bioassessment surveys. Surveys occur between April and June, on Tuesdays, Thursdays, and occasional Saturdays. Prior to volunteering, we ask that all participants join us for a pre-survey training. This year’s training will be held on Saturday, April 20th at Pennington Creek. 

Registration for our annual training is required. To register, please visit: For more information, please see the flyer below, or reach out to us directly at

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: