Brigham City officials trying to find the cause of dead fish at Mantua Reservoir

MANTUA – Hundreds of dead fish are floating in the Mantua Reservoir. 

This comes after the lake was treated for algae blooms. But city workers say they can’t be sure whether those chemicals had anything to do with what’s happening now. 

Workers with Brigham City estimate about 300 fish are dead. They’re working with a group of scientists to try and get some answers. 

Still, the water at Mantua Reservoir is a lot less green and more clear. 

“Absolutely. It’s almost too clear right now,” said Ted Grove, who says the water can make fishing a little more difficult. 

But then there’s the other thing people can easily see through the water. 

“Yeah there’s been a lot of dead trout, so that’s a little concerning,” Grove said. 

He’s not the only one who’s noticed. 

Pilot study at Mantua Reservoir

Just last month, scientists with Blue Green Water were at the reservoir running a pilot study of a solution they say essentially oxygenates the algae blooms, which causes them to die without harming the wildlife. 

Glen Palmer says he is hoping no more fish were affected. 

“I hope it didn’t kill all the fish. That’d be sad,” he said. 

Palmer says while he does worry about what he’s seeing, he’s hesitant to jump to any conclusions. 

“That’s a normal thing when they plant fish, so many of them don’t survive,” he said. 

The Utah Division of Wildlife Resources just planted about 10,000 trout at the reservoir.

It’s not uncommon for a small percentage to die in the process. However, Brigham City workers and scientists want to be sure. 

What officials have to say

Derek Oyler, Brigham City administrator, said the one thing workers have found is less oxygen than they’d normally find in the water this time of year. 

“We can’t determine whether that’s just a normal die-off or whether the lower dissolved oxygens are maybe what’s causing it, but we’ll continue to work on that,” he said. 

In the meantime, Grove said from what he’s seen the bass are still healthy here. He’s hopeful those water treatments will eventually lead to a healthier future for one of his most frequented fishing spots. 

“I wouldn’t say favorite, but it’s close and easy. I call it cheap thrills,” he said. 

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