Grizzly Reservoir needs to be drained again after gate damage found

During last year’s rehabilitation efforts to maintain Grizzly Reservoir’s structural integrity, damage to an outlet gate that will cause a second, future drawdown, or draining, was discovered.

The outlet gate is what allows water to be released from Pitkin County’s Grizzly Reservoir into Lincoln Creek, according to Division Manager of Water Resources for Pueblo Water Alan Ward. It’s a dual-stage gate, meaning it has two separate gates — one smaller and one larger — used to determine how much water is released. 

The smaller, one-foot gate is the one where damage was identified during the 2024 summer drawdown. While Ward confirmed the gate as a whole is still operating, the smaller gate is no longer moving independently of the larger gate. 

“We have a little less fine control over the reservoir releases,” Ward said, noting that the damage “will get worse over time.”

While it’s unclear what caused the damage to the outlet gate, Ward said it’s most likely the age of the gate — both the larger and smaller ones were installed in the 1980s. There were also a large number of avalanches in the area around 2015 causing a number of trees to get washed into the reservoir which could have potentially damaged the gate. 

“It’s hard to say exactly what caused it,” Ward said.

Water is still currently being released down Lincoln Creek to prop up stream flow on Lincoln Creek and the Roaring Fork River. The goal for the drawdown is summer 2026, after the replacement gate is designed and permitted. 

And after the drawdown in 2024 caused water discoloration in Lincoln Creek and the Roaring Fork River, Ward said there will be a new plan for the draining in order to mitigate for what happened previously.

“When the reservoir gets completely drained, the last bit of water has fine suspended sediment that stays in the water and discolors it,” Ward said. “As part of our plan to drawdown the reservoir for the gate repair, we’re making some changes to our procedure to minimize impacts to our water downstream. We think that we can take that last bit of water and pump it over into a different pond, and hold it onsite rather than release it downstream.”

The draining will also provide an opportunity to put liner behind the gate — while last summer’s construction centered around lining the face of the dam to protect the steel, one strip down the center behind the gate was left out because the gate’s attachment to the dam made it difficult to access.

David Boyd, public affairs officer for White River National Forest, said it’s unlikely this upcoming project will impact public access to the area. 

“We’re not anticipating there being access issues,” Boyd said. “We don’t have a proposal yet, but we’re not anticipating (it) based on discussions so far.” 

This is part one of a two-part series looking into updates of the Grizzly Reservoir post-2024 construction.