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Improvement in Blue-Green Algae in Clearlake

FOR IMMEDIATE RELEASE: Improvement in Blue-Green Algae (Cyanobacteria) in Clear Lake:  all below ‘Caution’ Level.

Lake County– We are happy to report continued improvement in water sample testing for cyanobacteria in Clear Lake.  The most recent lab results received on September 13, 2018 for the monitoring conducted on September 4, 2018 for this specific algae detects results at 6 of the 18 sampling sites, but all six of these are below the caution threshold. This is a significant improvement from previous levels, and if this trend continues with the next sampling in two weeks, we will be able to remove all of the warning signs from the lake.  At this point, we plan to continue posting previously affected sites (CL-4, CLOAKS01, ELEM01 and SHADY01) with “Caution” signs, and re-evaluate when the next sampling results are analyzed.

The recommendation is based on the potential health risks from the algae, which over the last few months has been blooming at varying levels in all three arms of the Lake (Upper Arm, Oaks Arm, and Lower Arm).  Public Health follows state guidelines in waiting for minimum two sampling results at a lower level before changing signs; or two non-detectable results before removing signs. However, overall conditions are improving, with no warning or danger levels at this time.

Water monitoring is done by Big Valley Band of Pomo Indians and Elem Indian Colony.

Cyanobacteria Map Sept 2018
Cyanobacteria Results Sept 2018

The Redbud Park boat launch location, which was at a Danger level from a sample taken on August 7, still shows a detectable level (but below caution threshold), and it is close to a drinking water supply. The Clearlake Oaks location is also close to a drinking water supply, but it is now “non-detectable.” Sampling of drinking water completed ¬¬August 17, 2018 and August 28, 2018 from these locations showed results below detection levels for microcystin.

Health Concerns

Blue-green algae can pose health risks, particularly to children and pets. We urge people to choose safe activities when visiting the Oaks Arm and parts of the Lower Arm of Clear Lake and wherever blooms are visible.  It is strongly recommended that people and their pets avoid contact with water and avoid swallowing lake water in an algae bloom area.

Recommendations from the Statewide Guidance on Cyanobacteria and Harmful Algal Blooms:

  • Take care that pets and livestock do not drink the water, swim through algae, scums or mats, or lick their fur after going in the water.  Rinse pets in clean water to remove algae from fur.
  • Avoid wading, swimming, jet or water skiing in water containing algae blooms, scums or mats.
  • Do not drink, cook or wash dishes with untreated surface water from these areas under any circumstances; common water purification techniques such as camping filters, tablets and boiling do not remove toxins.
  • People should not eat mussels or other bivalves collected from these areas.  Limit or avoid eating fish from these areas; if fish are consumed, remove the guts and liver, and rinse filets in clean drinking water.
  • Get medical treatment immediately if you think that you, your pet, or livestock might have been poisoned by blue-green algae toxins.  Be sure to alert the medical professional to the possible ontact with blue-green algae.  Also, make sure to contact the local county public health department at (707) 263 - 1090.

What is the Problem?
Cyanotoxins are produced by bacteria called cyanobacteria.   They are an essential part of the environment that have existed for millions of years and produce oxygen.  Under certain conditions, they multiply excessively and form visible clumps that can appear as cut grass in the water or blue-green, white or brown foam, scum or mats that can float on the water’s surface and accumulate along the shoreline and boat ramp area.

On occasion, they produce toxins that can cause harmful effects in people and animals if exposed through ingestion, inhalation of aerosolized water or direct contact.  As environmental factors change, most harmful algae blooms resolve over time.   However, when cyanotoxin are known to be present, re-testing the water after it has cleared and allowing at least two weeks to pass after no toxins are found is recommended.

What are the health effects?
When the toxins are ingested in large amounts they can cause:

  • Sharp, severe stomach problems like diarrhea and vomiting.
  • Liver damage that may take hours or days to show up in people or animals.
  • Numb limbs, tingling finger and toes or dizziness.

Possible health effects of animal exposure to a toxic bloom

  • Weakness, staggering, difficulty breathing
  • Convulsions
  • Vomiting or diarrhea

Signs of a toxic bloom may include: a large number of dead fish, waterfowl or other animals, or sudden, unexplained sickness or death of a cat or dog that has been exposed. It is not possible to tell if Cyanobacteria are toxic by looking at them. There is ongoing research on potential health effects of exposure to the toxins produced by some species of cyanobacteria. The California Department of Public Health evaluates any new findings and makes updates to guidance materials as necessary.

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