Exposure characterization of a cyanobacteria harmful algal bloom (CHAB) at Clear Lake, CA: Data Collection Methodology
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Potentially harmful freshwater algal blooms of cyanobacteria (CHAB) are increasingly reported among US surface waters. Clear Lake in Lake County, CA is regularly impacted by CHABs during the spring through fall. As part of the US Environmental Protection Agency (EPA)’s effort to characterize CHAB exposures, air and water samples were collected at a pier adjacent to the shore at a public beach on five consecutive weekends during September-October, 2017. Air samples were collected for eight hours at 4-5 LPM; 20 Button samplers with fiberglass filters were collected in duplicate for endotoxin analysis; 20 closed-face, 25-mm MCE filters were collected in replicate for cyanotoxin analysis. Water samples were collected three times during each sampling day. A bucket was dropped from the pier to collect surface water from the top 10 inches; individual samples for analysis were collected from the bucket sample. Water samples were submitted to laboratories for analysis of endotoxin, phytoplankton, cyanotoxins, phycocyanin and chlorophyll-a. Water characteristics (temperature, pH, turbidity, dissolved oxygen) and weather condition (temperature, humidity, wind direction, wind velocity, rainfall) were recorded immediately following each sample collection period. Observations of human activities were made every hour throughout the sampling period, characterized by type of contact with water (no contact, hands/feet in water, partial submersion, full submersion, in boat, or on watercraft. The number of people engaging in each activity were counted by age group category (infants, toddlers, pre-adolescents, adolescents, adults). Dogs were counted due to recent reports of respiratory illness and death among dogs swimming in a CHAB. Initial results indicate that the sampling protocols allow for quantitation of cyanotoxins and endotoxin, and associated human activity. This abstract does not necessarily reflect EPA policy.