A toxic blue-green algae bloom was recently identified at New Hogan Reservoir by the Central Valley Regional Water Quality Control Board.

Although the level of toxicity was deemed to be low, public health officials are warning recreationalists to be aware, especially those with small children and dogs.

“While the bloom at New Hogan Lake is subsiding, it is important that everyone who will be enjoying our lakes and reservoirs for wading and swimming have a basic understanding about potential health effects of certain types of algae that appear during the summer season,” read a Calaveras County Environmental Health Department press release issued May 29. “This understanding includes how to identify its presence in the water and practical precautions to take if concerned.”

A normal part of the ecological cycle in warm surface waters, algae blooms appear naturally every spring and summer in lakes and reservoirs and throughout the county. That said, sub-specie-types of the bloom, known as cyanobacteria, can have detrimental health effects.

Sue McConnell, section chief for the Central Valley Water Board, said that algal blooms were also detected via satellite in the Salt Springs Valley Reservoir in northeast Calaveras County, but haven’t been tested for toxicity yet.

She said a number of factors could be promoting algal blooms, some of which include warm weather and stagnant water. That said, the satellite tool also found that “blooms have been subsiding, so cyanobacteria seem to be lessening.”

Potential health effects

Common health effects for humans exposed to blue-green algae include rashes or other skin irritation, allergy-like reactions, runny nose or sore throat, the press release states. If ingested in large amounts, symptoms could include sharp severe stomach aches, diarrhea and vomiting, liver damage, numb limbs, tingling fingers and toes and dizziness.

“While no serious cases of local residents developing complications or illness from blue-green algae have been reported to the local health department, those who use the lake should be aware of the threat to avoid becoming sick,” according to Dr. Dean Kelaita, Calaveras County public health officer.

Common health effects for dogs exposed to the algae include weakness and staggering, difficulty breathing, vomiting and diarrhea, or even convulsions and death.

How to identify toxic algae blooms

There is no local monitoring program for blue-green algae in Calaveras County, but heavy blue-green algal blooms are typically readily visible. They are often described as looking like pea soup or spilled paint on the surface and can produce a swampy odor when the cells break down.

Other times, lighter blooms may be less easy to detect, floating beneath the surface or on the bottom of a water body. The best advice is to check with the local recreational or water body manager and inquire if they are aware of any harmful algal blooms occurring.

If something doesn’t look right in the water, notify the local recreational or water body manager, and stay out of the water.

Recommended precautions

For visitors concerned that a blue-green algae bloom might be present, here are some common precautions or healthy water habits that all water users should follow:

• Heed all instructions on posted advisories if present.

• Avoid algae and scum in the water and on or at shoreline.

• Keep an eye on children and pets (dogs).

• If a suspicious algae bloom is present, do not let pets and other animals go into or drink the water, or eat scum and algal accumulations on the shore.

• Do not drink the water or use it for cooking.

• Wash yourself, your family and your pets with clean water after water play.

• When catching fish, throw away guts and clean fillets with tap water or boiled water before cooking.

• Avoid eating shellfish if an algal bloom is present.

For more information, contact the Environmental Health Department at 754-6399.


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