Officials Warn of Toxic Algae in Northern California Waters. Here’s How to Identify It.

Northern California authorities are urging residents and visitors to be cautious around local rivers and lakes due to the potential presence of toxic blue-green algae, also known as cyanobacteria. The warning comes as warm, slow-moving waters create ideal conditions for harmful algae blooms, which can pose serious health risks to both humans and animals.

The Humboldt County Department of Health and Human Services has identified telltale signs of cyanobacteria, including slimy layers of dark green or brown scum on the water’s surface and a murky, pea soup-like appearance. Authorities advise avoiding swimming in or drinking from water with these characteristics.

Exposure to cyanobacteria can result in various health issues. In humans, symptoms may include skin, ear, eye, nose, or throat irritation, headaches, and gastrointestinal distress such as vomiting and diarrhea. Severe exposure can lead to more serious conditions like incoherent speech, seizures, or paralysis. Pets, especially dogs, are highly susceptible and may show signs such as drooling, lack of energy, stumbling, and loss of appetite.

To minimize risk, avoid any contact with water that appears contaminated. Do not swim, wade, or let pets play in affected waters. Additionally, refrain from using water from these sources for cooking or washing dishes. If consuming fish from these areas, ensure to remove the guts and liver and rinse the fillets thoroughly with tap water.

If you encounter a suspected algae bloom, report it to the authorities by emailing CyanoHAB.Reports@waterboards.ca.gov, calling 844-729-6466, or using the bloomWatch app. Photos can also be sent to envhealth@co.humboldt.ca.us. Immediate medical attention is crucial if you suspect exposure.