One of the methods San Diego Coastkeeper uses to identify polluted water is to take a survey of the insect life within a target waterbody. Ambient and nutrient-based water quality monitoring processes – such as those conducted over our ten year Water Quality Monitoring Program or in our ongoing winter stormwater monitoring efforts – look at the chemical constituents found in our creeks and streams. These numbers, however, only tell a partial story. When combined with data from bioassessments, it is possible to get a much more holistic view of the stream health and a clearer picture of how the chemical constituents we test for really affect local streams.

Resources permitting, bioassessments are conducted in the spring, when our rivers are flowing most consistently. Typically, one or two rivers or streams are selected, and adventurous, highly trained volunteers are deployed to conduct a number of rigorous assessments.

Because some insects are more sensitive to pollution than others, the information collected about the types and numbers of insects living in a waterway helps us determine whether the water is healthy enough to support the species that call it home.

San Diego Coastkeeper’s bioassessments go hand in hand with our past Water Quality Monitoring program efforts, which analyzed 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 a particular waterway home. This gives us a deeper, more complete understanding of water quality in San Diego County – and that is the first step to making our water healthy for everyone to enjoy.