SACRAMENTO COUNTY (CBS13) — Sacramento County health officials are warning the public and their pets to stay away from water that has scum layers or any other bloom of blue-green algae.

Signs are up along Sacramento’s waterways warning to stay out of the water, because of the toxic algae thriving in California’s drought and warm temperatures.

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“The drought conditions are similar to conditions that favor algae growth,” said health department spokesman John Rogers. “Low water flows,river slows down, and allows areas for algae to accumulate.”

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The algae has already proven deadly, as a local veterinarian said a dog has died after swimming at Sand Cove Park.

Health officials say blue-green algae is a type of bacteria that’s naturally found in fresh and marine water. Warm, slow-moving waters are rich in phosphorous and nitrogen that can cause algae growth in late summer and early fall. It’s only a health concern when it’s found in large quantities.

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Exposure can cause a rash, an allergic reaction, or gastrointestinal problems. In large quantities, it can cause neurological or liver damage and even death, especially in animals.