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Weather, BuRec Boost Snake Flows by Staff Jackson Hole Zone, May 31, 2004

Snake River flows will jump this week as the Bureau of Reclamation releases 9,000 cubic feet of water per second from Jackson Lake Dam in an attempt to mimic a natural spring run-off.

Meanwhile, Mother Nature has been doing her part to swell tributaries, boost the dwindling snowpack and fill reservoirs by dumping 1.2 inches of moisture on the valley since Tuesday. On Saturday evening, two inches of snow fell in town, according to weatherman Tom Dunham.

On Friday, Snake River flows hovered around 6,000 cfs at Alpine, but by mid-day Sunday had jumped to 8,440 cfs. Jackson Lake is now at 54 percent of capacity and the snowpack in the upper Snake River region is at 44 percent of average for this time of year.

The spike in river flows is slated to peak by the end of this week and last for about seven days, according to the bureau. The bureau is attempting to design and time releases from both Jackson Lake and Palisades dams to more closely resemble what would have occurred prior to the construction of dams.

Some studies suggest a more natural flow regime keeps a river healthy and boosts the reproductive success of native cutthroat trout.

Following the “spring flush,” the bureau would drop flows to less than 2,500 cfs by July 5. The flows would gradually taper off but remain above 2,000 cfs until at least Sept. 6, according to the schedule.

Low flows most of the summer will be a boon to anglers, who have complained that high flows the past three summers have ruined the fishing season.

“Kudos to Bureau of Reclamation for coming over here and seeing our points and trying to mediate some type of balance,” said Rhett Bain, owner of Reel Deal Anglers, after seeing the schedule.

Last summer, flows ranged as high as 5,000 cfs during the summer. Anglers say anything above 3,000 cfs ruins the fishing, in part, by making the river too swift to hold a boat near a fishing hole.

Scenic float trip operators, however, favor high flows and say anything below 1,800 cfs makes it too difficult to float fully loaded rafts. The bureau will try to keep flows at a minimum of 2,000 cfs to keep rafters floating.

“There’s got to be some sort of balance,” Bain said Friday.

The flow schedule, however, is not set in stone and could fluctuate depending on run-off and weather. The current bout of rain has been a benefit to downstream irrigators, who are slated to run out of water in mid-August. With the cool weather, some irrigators have been able to turn off sprinklers and conserve more water for August.

Even with the rain, Jackson Lake Reservoir will not fill this summer. The flow schedule shows the reservoir peaking at 450,000 acre feet, less than 54 percent of the 847,000 acre-foot capacity. The reservoir is predicted to drop to 50,000 acre feet by September.

Despite a wet May, the basin is still playing catch-up with precipitation measuring only 82 percent of average since October.