Algal bloom advisory lifted for Big Lagoon

BIG LAGOON – The harmful algal bloom advisory for Big Lagoon has been lifted after water quality results from recent sampling showed cyanobacterial toxin concentrations below health advisory thresholds according to the State Water Resource Control Board.

The original advisory was placed on the lagoon in August after samples from Big Lagoon tested high for toxins produced by cyanobacteria.

Typically, cyanobacteria or harmful algal blooms (formerly referred to as blue-green algae) warnings come out between late July and early August, coinciding with low flows and sustained high temperatures which may contribute to cyanobacteria growth.

As the weather and water cool down in the late fall and winter months, harmful algal blooms are less likely to occur.

The presence of cyanobacteria has been previously confirmed in water bodies within Humboldt, Mendocino and Lake counties including the South Fork Eel River, Van Duzen River, Trinity River, Clear Lake and Lake Pillsbury.

The toxins produced present a risk to humans and their pets.

Most blooms in California contain harmless green algae, but it is important to stay safe and avoid contact with algal mats. If a suspected bloom is observed, please contact the Humboldt County Department of Health & Human Services, Division of Environmental Health (DEH).

It is anticipated that harmful algal blooms will increase in intensity, frequency and duration with climate change and especially in drought years.

Individuals living near surface water bodies, or their tributaries can help reduce the potential for harmful algal blooms by properly maintaining their septic systems, limiting the use of fertilizers, and preventing nutrient pollution from entering waterways.

To learn more about cyanobacteria and harmful algal blooms, visit the state of California’s website at

For information on conditions occurring within Humboldt County, contact DEH at (707) 445-6215 or (800) 963-9241. Photos of suspected blooms can also be emailed to