Jackson Lake dam drawdown
Rick Smith
Jackson Hole (WY) News & Guide
Wednesday, September 13, 2023
BuRec once again eyes sharp Jackson Lake Dam drawdown
Bureau of Reclamation will host public meeting Thursday and finalize plans Friday.
When the U.S. Bureau of Reclamation starts cutting flows from Jackson Lake Dam later this month, the cut will be less drastic than a controversial 2021 flow reduction that stranded fish and raised river runners’ hackles.
But it’s still not quite what the river community has been looking for: a longer drawdown intended to give fish more time to move out of side channels and into the Snake River’s main channel.
Part of that is because the Bureau of Reclamation wants more data showing how drawdowns affect fish. Part of that is because, in some ways, Wyoming Game and Fish Department officials agree.
The agency’s tentative plan is to begin reducing the release from roughly 2,300 cubic feet per second on Sept. 25 to the winter flow of 280 cfs by Oct. 2. The bureau will host a public meeting Thursday and meet with stakeholders before finalizing the plan.
The bureau gave the State of Wyoming and other stakeholders the option to boost flows this summer, which would have allowed more water to spill from Jackson Lake Dam, and required the bureau to spill less water this fall, thereby allowing officials to protract the drawdown over more time. But Game and Fish wondered whether boosting summer flows could lead more fish to enter side channels, trapping more fish when flows were cut in the fall — even if flows were reduced over a longer period of time.
Darren Rhea, Game and Fish’s regional fisheries supervisor, said he was the one who wanted more data.
“We lack the general understanding of how this drawdown dynamic functions,” Rhea said.
Brian Stevens, water management supervisor for the bureau’s office in Burley, Idaho, said the department “received feedback that we don’t have all the data we need” to boost summer flows and prolong ramp down.
“There’s always opportunity to make the ramp down longer, but it comes with different risks,” Stevens said.
So, bureau officials are sticking with their tentative plan: a week- or week-and-a-half-long drawdown by Oct. 2, the day repair work is slated to begin on the dam.
Bureau officials will determine the start date for the drawdown after meeting Friday with Game and Fish, Grand Teton National Park and other stakeholders.
The winter dam release of 280 cfs is the minimum flow Game and Fish says is necessary to keep water trickling through the Oxbow Bend, a stretch of river in Teton park that boasts views of Mount Moran and a species of bluehead suckers that Game and Fish doesn’t want listed as “threatened” under the Endangered Species Act.
Stevens said the Bureau of Reclamation needs to reduce the amount of water stored in Jackson Lake to about 575,000 acre-feet for rehabbing some of the dam gates to prevent sediment and debris buildup that’s caused issues in the past. There are about 626,000 acre-feet of water in the lake now.
That’s where we’re limited,” Stevens said. “That’s the sideboards of the ramp-down operation.”
The public will have an opportunity to ask Bureau of Reclamation officials about the drawdown — and its plans to revise guidelines for managing the Snake — this week. The bureau is set to hold a meeting about water management from 3 to 5 p.m. Thursday at Teton County Library, with a virtual option for dialing in here. The meeting ID is 244 666 171 463 and the passcode is WWKbur.
If the bureau’s proposal sticks it would mark an improvement from the fall of 2021, said Orion Hatch, executive director of the Snake River Fund. But it falls short of the two-week drawdown that Grand Teton National Park has requested in recent years, along with anglers and other river runners.
“The volume there and the duration is less significant than what we saw in 2021 with the super-sharp drawdowns, so that’s encouraging,” Hatch said. “But what we’re looking for in the long run is spring and fall management of flows that as closely as possible resemble what would happen in a natural system.”
During the summer of 2021, water managers were releasing as much as 5,000 cfs from Jackson Lake Dam for one month and 4,000 or more for two months. The bureau then cut the release abruptly from 3,000 cfs on Sept. 30 to 280 cfs by Oct. 5, leaving fish stranded in side channels and volunteers scrambling to recover and relocate them in the river. The National Park Service had asked the bureau for a two-week drawdown, not five days.
The drawdown this year will start from a lower flow — about 2,300 cfs rather than 3,000 cfs — and take slightly more time. While that proposal is comparable to usual custom, fisheries managers such as Rhea and advocates for recreational river use such as Hatch want to study drawdowns more.
A study published earlier this year by the Teton Conservation District showed that the rapid 2021 drawdown disconnected side channels in a 3-mile stretch of the Snake north of the Wilson bridge, and caused the river to lose 23% of its surface area. It also indicated that surface area loss was particularly acute when dam release dropped from 1,280 cfs to about 1,000 cfs, harkening back to a study from the 1980s when Game and Fish scientists recommended a minimum flow of 1,290 cfs from Jackson Lake Dam. In contrast to keeping water in the Oxbow, that flow was meant to keep water in side channels from Pacific Creek to Moose.
But the Conservation District study did not connect the dots from hydrology to ecology. In other words, it didn’t study how drawdowns and the resulting reductions in surface area and side channel connections impacted fish and invertebrates. Now, Game and Fish wants to do that, working with graduate researchers from across the Mountain West to determine how flow reductions impact aquatic life.
“Without that information I was uncomfortable requesting some level of alternative,” Rhea said.
Hatch, meanwhile, said floaters, anglers, fisheries managers and federal park officials who are organizing the Snake River Headwaters Watershed Group are trying to recruit University of Wyoming researchers to study similar questions. The Conservation District also is eyeing future research.
Though this year’s proposal for reducing the flow is not exactly what Rhea and Hatch want — both agreed that a longer drawdown is better — they said the Bureau of Reclamation has been much more engaged with other agencies earlier in the summer, something anglers and fisheries managers have been asking for.
The discussion about augmenting summer flows to lengthen the drawdown happened earlier this summer. Rhea described that as an “olive branch” to the people and groups who care about the Snake River.
Rick Smith
5264 N. Fort Yuma Trail
Tucson, AZ 85750
Email: rsmit...@comcast.net