Recreational Water Users Urged to Be Vigilant About Harmful Algal Blooms
Published: June 28, 2020
Now that Summer is here and recreation on the local waterways is increasing, the Sonoma County Department of Health Services (DHS) and the State Water Resources Control Board request the public be mindful of freshwater harmful algal blooms (HABs) in rivers, lakes, and reservoirs. Recreating in
waterways contaminated with HABs can cause illness, and is especially harmful to children and pets.
Out of an abundance of caution, Friday morning June 26, 2020Caution Advisory signs for HABs were posted along the Salmon Creek lagoon in Bodega Bay. The Caution Advisory recommendations include staying away from algae and scum in the water, preventing pets and other animals from going into the water, and keeping
children away from algae in the water or accumulated along the shore. As the summer season progresses, we anticipate posting advisory signs in other freshwater recreational areas and remind the public to heed the advisory message if they see these signs.
About HABs and Blue-Green Algae
Most HABs are formed by cyanobacteria, also called blue-green algae (BGA), which are small microbes that live in nearly every habitat on land and in the water. Increased water temperatures, slow moving water, and excessive nutrients cause BGA to multiply and form these harmful blooms.
It is important to
distinguish BGA from other algae and non-toxic water plants that are not thought to pose hazards to health. Harmful blooms can develop thick paint-like floating scums on the water’s surface, form mats on the bottom of a waterbody, accumulate along shorelines, or even look like small particles
floating at various depths. The harmful blooms can be in a variety of colors such as green, white, red or brown.
Who is most at risk?
BGA and the toxins they can produce have the potential to harm the environment, people, pets, wildlife or livestock. Dogs and children are most likely to be affected because of their smaller body size, increased potential to swallow water while swimming and tendency to stay in the water
longer. Recreational exposure to BGA and associated toxins can cause eye irritation, skin rash, mouth ulcers, vomiting, diarrhea and cold and flu-like symptoms.
Dogs are susceptible because they tend to drink while in the water and lick their fur afterward, increasing their risk of exposure and illness. Symptoms with animals include vomiting or diarrhea, lethargy, abnormal liver function test results, difficulty breathing, foaming at the mouth, seizures
and sometimes death.
Remember these tips to be safe
DHS and the California Water Boards recommend that people practice healthy water habits while enjoying the outdoors this summer at your local lake, river or stream:
- Heed all instructions on posted advisories if present
- Avoid algae and scum in the water and on the shore
- Keep an eye on children and pets
- If you think a HAB is present, do not let pets and other animals go into or drink the water or eat scum/algal accumulations on the shore
- Don’t drink the water or use it for cooking
- Wash yourself, your family and your pets with clean water after water play
- If you catch fish, throw away guts and clean fillets with tap water or bottled water before cooking
- Avoid eating shellfish if you think a HAB is present
Get medical treatment immediately if you think that you, your pet, or livestock has gotten sick after going in the water. Be sure to alert the medical professional to the possible contact with BGA. Also, make sure to contact DHS Environmental Health at (707) 565-6565.
To report a bloom, do one of the following:
For more information, please visit the DHS Environmental Health webpage for BGA at
Anyone can track where HABs are located statewide, by visiting the State Water Boards portal map at: