Canyon Lake HABs Monitoring Protocol

In recent years, Harmful Algal Blooms (HABs) have been occurring more frequently, lasting longer, and producing higher levels of dangerous toxins throughout California waters than in the past. As a result, adverse impacts to the health of humans, domestic animals (dogs and livestock, in particular), and wildlife are on the rise. In some areas, the occurrence of HAB events is increasing from predominantly summer blooms to year-round blooms, probably due to increasing temperatures associated with climate change.

Canyon Lake is a gated community in Riverside County, with more than 10,000 residents. In June 2019, MBC delivered a final report outlining recommendations for cost-effective monitoring of HABs in Canyon Lake to the Elsinore Valley Municipal Water District. The proposed monitoring program focused on assessing potential health risks associated with swimming at five beaches, as well as the risks associated with kayaking, waterskiing and other recreational activities in open water areas throughout Canyon Lake. The proposed monitoring program includes a relatively inexpensive screening technique based on the identification of key toxin-producing genera of cyanobacteria in water samples collected at several lake locations. More expensive laboratory measurements of toxin concentrations at these locations would only be undertaken when the screening tool indicates the presence of dangerous cyanobacteria in lake waters.

The proposed monitoring program also includes guidelines for how to interpret toxin monitoring results and when to post warning signs to restrict public recreation in Canyon Lake whenever dangerous toxin levels that could threaten human health are detected in the lake. Guidelines also are provided to indicate when warning signs may be removed after toxin levels have dropped below dangerous levels.

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