By Jim Stanford on May 17, 2013
Heading into a second year of drought with reservoirs already drawn down and snow melting fast, the U.S. Bureau of Reclamation is planning to release nearly twice as much water as usual in the Snake River this summer.
Barring prolonged wet weather, water managers will release 4,000 cubic feet per second from Jackson Lake Dam through September.
The agency projects to draw down Jackson Lake reservoir to about 18 percent of capacity. At best, the bureau will fill Palisades Reservoir to about 50 percent of capacity before draining it nearly dry to meet irrigation needs in Idaho.
Mike Beus, BuRec operations manager, presented his projections along with weather forecasts at the agency’s annual water meeting last night in Jackson. A crowd of anglers, irrigators, farmers and rafting guides attended.
Beus painted a stark picture of less water available for storage in the basin, temperatures skyrocketing to 90 degrees in Boise last week and snow melting in the high country above Jackson Lake at a rate of 2 inches per day. While this weekend’s cool, wet weather offers some relief, temperatures were 10 degrees above average for the first half of May, he said.
“The normals are changing,” he said.
The projected flows on the Snake are excellent for scenic and whitewater rafting but not optimal for fishing. With nearly twice as much water, native cutthroat trout will be harder to catch. But the steady flow is preferable to a sudden and dramatic rise late in the season to meet irrigation demands, as happened in 2002, one of the years most closely matching current conditions.
Water management in the Snake basin is highly complex, with each decision affecting the operation of dams downstream. Managers must balance the needs of endangered Pacific salmon, sovereign Indian tribes, irrigators, farmers, cutthroat trout, anglers, outfitters, rafters and motor boaters, among others.
As is his custom, Beus presented a slew of graphs with lines as intricate and interwoven as the strands of his long, grey beard. Looking at runoff and storage from years past, he saw similarities to 2007, 2003, 2002, 1991 and 1989 — all relatively dry.
The peak flow on the Snake through Jackson Hole is likely to occur within the next week, he said. The release at Jackson Lake Dam hit 4,000 cfs today, and the river was running 8,000 cfs at Moose. The flow in the canyon likely will exceed 14,000 cfs this evening.
The early runoff has forced the contractor building the new pathway bridge over the Snake to cease work in the river. Crews had been struggling to install the second piling; instead they will begin building the east abutment.