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Signs on the docks around Pineview Reservoir warn about a toxic algae bloom in the reservoir on Thursday, Sept. 6, 2018. The algae bloom was confirmed the week before and can cause rashes, vomiting, headaches and more for people or animals who come into contact.

A harmful algae bloom continues to cause problems at Pineview Reservoir, but health and utility officials say those downstream don't need to worry about their water supply.

The Weber-Morgan Health Department first confirmed a potentially toxic bloom in the reservoir on Aug. 31. Blue-green algae grow rapidly in warm, sunny water that's high in nutrients. The blooms can contain cyanobacteria, which can cause fever and abdominal problems in people and can be deadly for pets. 

This is the first known harmful algae bloom to develop in Pineview Reservoir.

"The elevation of the water is low. It’s been hot," said Michela Harris, the health department's director of Environmental Health. "It's just a perfect storm for something to develop."

The algae is also moving up and down the water column, Harris said.

"We’ve had questions from people, 'if I don’t see it at the beach does that mean it’s gone?'" she said. "No, that doesn’t mean it’s gone. We’re detecting algae deeper, not just at the surface."

Harris and health officials with the Utah Department of Environmental Quality are still waiting for sample results to determine the Pineview bloom's toxicity. In the meantime, they're advising swimmers to stay out of the water and boaters to avoid green, scummy areas. Anglers should thoroughly clean fish and toss the guts. 

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Most of Ogden City's drinking water supply comes from Pineview Reservoir, as does much of the secondary water in the area, but water managers say the bloom is not a cause for alarm.

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Boaters circle Pineview Reservoir on Thursday, Sept. 6, 2018. A toxic algae bloom was reported in the reservoir the previous week. While the reservoir is still open, swimming, waterskiing and other activities in the water are discouraged.

"The algal bloom can’t make it past our filters in the treatment plant, so there’s not threat to the community," said Kenton Moffett, Ogden Public Utilities manager.

Algae mostly causes a headache for public works employees, since algae mucks up treatment equipment and makes operations difficult.

Moffett said his crew has been keeping an eye open for algae in Pineview for more than a month since conditions have been favorable for blooms. He confirmed its the first known harmful bloom in the reservoir

"This is different for us, but we’re dealing with it," Moffett said. "It’s been a pain to deal with for sure, but it’s under control."

Outdoor irrigation water from Pineview isn't filtered or treated, but Darren Hess with Weber Basin Water Conservancy District said customers shouldn't worry about the secondary supply.

"We’re not seeing the levels that it would be toxic at this point," he said.

Still, with any untreated water supply, Harris said it's best to be cautious when filling wading pools or playing in sprinklers.

"If you wouldn’t get into it at the source, it’s a smart idea to wait until this is resolved if it’s coming through your secondary water," she said. "If you’re flood irrigating a garden or something, I would make sure I’m washing everything really well before I ate it."

Contact Reporter Leia Larsen at 801-625-4289 or Follow her on or on Twitter @LeiaLarsen. 

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