Hyrum Dam might be too outdated to handle record runoff water, officials say

HYRUM, Cache County — Utah officials are watching a nearly 90-year-old water dam as it may be too outdated for the record amounts of water.

Upper Colorado Region Director for the Bureau of Reclamation, Wayne Pullan, said on Tuesday most reservoirs around the state are designed to contain large amounts of excess runoff.

However, there is so much runoff this year that it’s causing problems for the Hyrum Dam, located in Hyrum, in Cache County.

“This year is going to exceed 2011, which was our previous highest runoff that we’ve ever had,” Pullan said. “(Hyrum Dam is) not a large enough reservoir to take all of that runoff, and so we have to depend on the spillway to bypass the excess amount. That’s the way the dam was designed.”

Pullan said they are only at emergency level one, the lowest stage, but about 80% of runoff is left. That excess water could seep underneath the spillway, causing it to break up.

Because of the damages, safety crews are staging and standing by with gravel and boulders while constantly monitoring the spillway by remote camera.

“Out of an abundance of caution, we’re taking additional steps to ensure that we’re ready should we have that flow underneath the spillway and should that raise problems with the spillway foundation,” Pullan explained.

The dam and reservoir were designed in 1935, and the Bureau of Reclamation determined in 2016 that the spillway needed replacing. However, that work has been slow, but for a good reason, according to Pullan.

“Once you know that, the first thing we look at is (whether) can we refurbish the spillway we’ve got,” he explained.

Pullan said that the bureau has since reinforced many of the cracks that have formed over the years. He assures that the reinforcements should hold and the water should be able to pass as needed, but it doesn’t hurt to expect the unexpected.

“I’d be reassured by that. What that would tell me is that the Bureau of Reclamation and the South Cache water users who are responsible for this facility care about my safety,” he said.

The spillway is set to be replaced in 2026 or ’27. Pullan said all of their reservoirs and dams have emergency action plans, and this is just the lowest phase of that.

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