San Diego County has at least 360 known pollutant impairments in 166 bodies of water. How do we know? One of the methods that San Diego Coastkeeper uses to identify polluted water is to take a survey of the insects that live there.
Some insects are more sensitive to pollution than others. By collecting information about the types and numbers of insects living in a waterway, we are able to determine whether the water is healthy enough to support the species that call it home.
We conduct these studies, called bioassessments, with teams of volunteers along rivers and streams in San Diego County. In addition to collecting and identifying aquatic insects, the volunteers work together to measure physical characteristics of the streams such as sedimentation and the state of the stream bed. We usually conduct these assessments once a year, during the springtime when our rivers are flowing most consistently.
San Diego Coastkeeper’s bioassessments go hand in hand with Water Quality Monitoring, our program to analyze water samples for basic chemistry, nutrients, bacteria and toxicity. Because they go beyond measuring chemical components, bioassessments help us to make connections between the quality of our water and the health of our animals that call it home. This gives us a deeper, more holistic understanding of water quality in San Diego County – and that’s the first step to making our water healthy for everyone to enjoy.