8/30/13
Officials with the Humboldt County Department of Health and Human Services (DHHS) are urging users of the Mad River to avoid contact with algae in the lower Mad River in the area above the Blue Lake Bridge and below the Mad River Hatchery. This week, a dog wading in this area suffered symptoms consistent with those of ingestion of toxic blue-green algae. The dog survived and is recovering.
“A blue-green algae bloom can present a health hazard to those swimming or playing in the river, especially children and pets. We recommend that people stay out of the water where significant algae are present, and keep their dogs out of this part of the river at this time,” said Kevin Metcalfe, Consumer Protection Unit supervisor of the DHHS Division of Environmental Health. Other areas that are warm, slow, stagnant and muddy are to be avoided, especially areas with floating algal mats.
DHHS is aware of 11 dog deaths which may have been caused by blue-green algae poisoning since 2001. The dogs died shortly after swimming in Big Lagoon, the South Fork Eel River and the Van Duzen River. A nerve toxin associated with blue-green algae was found in the stomachs of the dogs that died on the South Fork Eel River in 2002. The same toxin was found in water samples from the South Fork Eel and Van Duzen rivers in 2009 just after two dogs died. This poison is the most likely cause of the dog deaths on these rivers. Dogs are more vulnerable than people because they may swallow the toxin when they lick their fur. The onset of symptoms can be rapid; dogs have died within 30 minutes to one hour after leaving the water.
Blue-green algae can be present in any freshwater body. It looks like green, blue- green, white or brown scum, foam or mats floating on the water. Usually, it does not affect animals or people. However, warm water and abundant nutrients can cause blue-green algae to grow more rapidly than usual. These floating algal masses or “blooms” can produce natural toxins that are very potent. Dogs and children are most likely to be affected because of their smaller body size and tendency to stay in the water for longer periods.
Potential symptoms in dogs following exposure to blue-green algae toxins can include lethargy, difficulty breathing, salivation, vomiting, urination, diarrhea or convulsions. People can experience eye irritation, skin rash, mouth ulcers, vomiting, diarrhea and cold or flu-like symptoms.
This summer, increased algae in the Mad River may be due to warmer coastal temperatures, low flows, added nutrients and warmer water temperatures.
DHHS officials recommend the following guidelines for recreational users of all freshwater areas in Humboldt County:
- Keep children, pets and livestock from swimming in or drinking water containing algal scums or mats.
- Adults should also avoid wading and swimming in water containing algal blooms. Try not to swallow or inhale water spray in an algal bloom area.
- If no algal scums or mats are visible, you should still carefully watch young children and warn them not to swallow any water.
- Fish should be consumed only after removing the guts and liver and rinsing fillets in tap water.
- Never drink, cook with or wash dishes with water from rivers, streams or lakes.
- Get medical attention immediately if you think that you, your pet or livestock might have been poisoned by blue-green algae toxins. Be sure to tell the doctor about possible contact with blue-green algae.
Human activities can have a big effect on nutrient and water flows in rivers, streams or lakes. Phosphorous and nitrogen found in fertilizers, animal waste and human waste can stimulate blooms. Excessive water diversions can increase water temperatures and reduce flows. People can take the following measures to prevent algal blooms in our waters:
- Be very conservative with the use of water, fertilizers and pesticides on your lawn, garden or agricultural operation.
- Recycle any “spent” soil that has been used for intensive growing by tilling it back into gardens. Or protect it from rainfall to avoid nutrient runoff.
- Plant or maintain native plants around banks. These plants help filter water and don’t require fertilizers.
- Pump and maintain your septic system every three to four years.
- Prevent surface water runoff from agricultural and livestock areas.
- Prevent erosion around construction and logging operations.
Contact the DHHS Division of Environmental Health at 707-445-6215 or 1-800-963- 9241 for more information. People may report unusual blooms or conditions, including pictures, to Environmental Health by emailing
Download the DHHS press release HERE.
