SANTA ROSA (CBS SF) — Sonoma County health officials posted ‘Toxic Algae Alert’ signs along Salmon Creek Tuesday, warning swimmers and fishermen of the potential dangers hidden below the waterway.

The State Water Resources Control Board said its staff responded to recent sightings of suspected harmful algal blooms in the Russian River, Salmon Creek and Gualala River.

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The lab results taken from material collected has confirmed that potentially toxic algal mats are growing on the bottom of rivers and may detach and become stranded on banks.

“Because children and dogs are most susceptible to serious health impacts, it is recommended that they avoid touching any suspicious-looking algal material found in the water or along river banks,” state officials warned.

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Sonoma County health officials have posted “Toxic Algae Alert” signs on Salmon Creek and “Check For Algae” educational signs on the Russian and Gualala Rivers.

“While harmful algal blooms are caused by algae or cyanobacteria that grow floating in the water, some grow attached to the bottom surface of waterways and can form algal mats,” officials said.

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The State Water Board recommends that people practice healthy water habits when visiting the rivers or streams:

  • Heed all instructions on posted advisories
  • Avoid algae and scum in the water and on the shore
  • Keep an eye on children and pets
  • If you think a harmful algal bloom or toxic algal mats are present, do not let pets and other animals go into or drink the water or eat scum/algal mats 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 harmful algal bloom is present