Recent testing yielded positive results for small amounts of toxic algae in Deadman Creek and visual observations made at Hummingbird and Odell Lakes in the 20 Lakes Basin may indicate toxic algae is also present in these two lakes. Toxic algae may exist in other sites on the forest.
Toxins are concentrated within the algal mats themselves and released episodically into the water when the algae dies or is disturbed.
For your safety, do not enter the water or drink in these areas. Filtering and/or boiling the water is not effective against this type of algae.
Prevent pets from drinking the water and eating or touching algae in the water and dried on the shore. In particular, prevent dogs from eating dried algal mats on shore.
Please report any large algal blooms and/or algae that is particularly bright, bubbly, strange-looking, or appears like a haze in the water.
Do not disturb algal mats in any way. Wading or swimming can cause toxins to be released into the water.
If you suspect a site has toxic algae, do not enter the water and do not drink water from the area. While some sites are signed based on testing results, it’s likely that algae exists in other parts of the forest. Don’t rely on signage alone.
According to the California Water Quality Monitoring Council, the following signs and symptoms may occur within 48 hours of exposure to a waterbody with a suspected or confirmed algal bloom:
- sore throat or congestion;
- coughing, wheezing, or difficulty breathing;
- red, or itchy skin, or a rash;
- skin blisters or hives;
- earache or irritated eyes;
- diarrhea or vomiting;
- headache; and/or,
- abdominal pain
If people show symptoms of cyanotoxin and/or cyanobacteria exposure after contact with water, or with scums or mats of algae, they should receive immediate medical attention.
Additional resources are available from the Centers for Disease Control and Prevention (CDC), and by contacting the California Poison Control Center (1-800-222-1222).
See the HAB-related Illness Tracking webpage for information on previously reported human illnesses related to HABs in California.