When green willows on the bank of the Snake River turn bright gold, it’s not just the start of fall. It’s also time to zap, net and release stranded fish back into the river.
After the drawdown of the Jackson Lake Dam, thousands of fish get stuck in isolated pools in the river’s side channels. In the immediate aftermath, Wyoming Game and Fish biologist Diana Miller leads a team of volunteers and advocates at Trout Unlimited and the Snake River Fund in a fish rescue that doubles as a species count.
The Bureau of Reclamation, the federal agency tasked with dam management, determines the timeline for releasing the final outflows of the season ahead of winter. After high flows all summer, the abrupt end to releases leaves side channels dry and aquatic species separated from the main stem of the Snake.
“This year, the initial plan was to be an incredibly slow ramp-down,” Miller said. “However, [the bureau] changed that plan because of input from water users downstream.”
The Wyoming Game and Fish Department and Trout Unlimited had asked for a more gradual ramp-down, with the goal of an easier transition into fall flows of 280 cubic feet per second from 5,000 cfs nearly all summer. The state agency believes a slower process gives fish more time to return to the main stem.
After proposing what would have been the slowest ramp-down in decades, the bureau reversed course the week it met with senior water rights holders. Idaho’s “first in time, first in right” system means farmers tend to have more sway than fish, especially in a drought year.
Like those across the country, farmers in Idaho’s Magic Valley struggled this year with the spring’s meager snowpack, hot and dry temperatures and little rainfall to fill in the gaps.
Though this year’s drawdown was still longer than last year’s, flows also started much higher to meet agricultural demands. For much of the summer, the dam released double the more typical average outflows. That also means more fish made habitats in the side channels.
Before the drawdown is complete, fish that had flocked to new habitats must return to the main stem to avoid death by freezing or low oxygen levels. (Jenna McMurtry/KHOL)
At 8% full in mid-October, the Jackson Lake Dam eventually neared all-time lows. This year’s “warm snow drought” hasn’t helped. Brian Stevens, the bureau’s chief engineer of the dam, could not speak to KHOL by press time.
“What we aim for, if we have enough runoff, is to draft from 100% full down to about 76% full going into winter,” Stevens told KHOL in August. “But this year we’re going to be between one to 10% full range by the end of the fall here.”
Earlier this month, Miller led a group of fish enthusiasts on an early morning outing on the Moose-to-Wilson stretch of the Snake where it runs through Grand Teton National Park. Transporting fish back into the river and keeping count of strandings kept the team busy until sunset.
“We’re going to electrofish each of those isolated pools and return those fish safely back to the Snake River,” said Alicia Brisson, during the early October rescue.
A conservation associate at the Jackson Hole chapter of Trout Unlimited, Brisson has coordinated several citizen-science monitoring projects this fall with Miller and other non-profit partners.
Wearing clunky backpacks with wires hanging into the isolated pools, she showed new volunteers how to first stun the fish, then net them. Miller then walks a bucket of fish not quite a quarter mile, where she gets a species count before releasing them back into the river.
“We’re doing this on a few pools and there’s probably hundreds of these pools across the Snake River,” said Miller, in between counts of dace, suckers and the occasional young cutthroat trout. “We’re happy to be doing what we’re doing and making whatever difference we can, but the reality is that this is happening on a very large scale.”
As Brisson zaps fish with an electrofishing pole, fly fishing guide and volunteer Sloane Bergien scoops young-of-the-year suckers into a bucket.
“The majority of the fish that we are rescuing today are the smaller next generation and the macroinvertebrates and the future health of our entire ecosystem,” said Bergien, a longtime guide at Wyoming Angling Company.
After an especially tough season, helping save next season’s fish hits close to home for the veteran fly fisher, who relies on the quality of the Snake for a living.
“We battled with high water most of the summer,” Bergein said of the less-than-ideal fishing conditions. “We battled unbelievable high temperatures, both with the sun and the atmosphere, but also with water temperatures.”
Sloane Bergien, left, transfers recently netted fish into a bucket for state biologist Diana Miller to count and release. (Jenna McMurtry/KHOL)
The Snake hit 70 degrees for weeks at a time this summer, prompting the state’s first voluntary fishing closure for the local stretch of river. The Jackson Lake Dam is unique in that it pulls water from a relatively shallow part of the dam, which, besides the weather, also contributed to the warmer temperatures.
“That’s just not healthy temperatures for our native cutthroat trout,” Bergien said.
Before the bureau changes its dam management approach, it wants to see more data that shows a connection between the pace of a drawdown and the impacts on aquatic life. This year’s effort adds a data point for a drought year.
Researchers from Idaho State University, the Teton Conservation District and the National Park Service have also spent the last few years working in tandem with Miller to collect data on other sections of the Snake. On the first day of a rapid drawdown, their studies show connectivity is already lost in the side channels.
Given that this year’s drawdown was still much slower than last year’s, Miller anticipated fewer stranded fish as a result. The numbers added up as she expected: 2,000 stranded fish in the same pools that saw 7,000 last year.
“If we can work with the Bureau of Reclamation to implement different ramp-down scenarios that might be more beneficial to fish, hopefully we don’t even have to do this anymore,” Miller said.
At least that’s the regional fish biologist’s long-term hope.
