Bureau of Reclamation officials still plan to hold off on releases from Jackson Lake Dam until the lake fills later this month, while the Snake River above Alpine is expected to reach its seasonal peak in the coming weeks.

On Tuesday morning, Jackson Lake was 72 percent full and flows in the Snake River Canyon above Alpine edged above 11,000 cubic feet per second for the first time in more than a week. Bureau of Reclamation water operations manager Mike Beus said that May precipitation was very close to normal. Although cold temperatures have continued to delay runoff, a long-range forecast calling for warmer weather could change conditions quickly.

“Slow melt describes our situation right now,” Beus said. “We have significant snow left at the upper elevations. With any luck, when we fill the lake we’ll still have some snow left and inflows left.”

On Tuesday, snow-water equivalent in the Snake River Basin was 138 percent of average, with the Phillips Bench site 154 percent of average and Togwotee Pass 129 percent of average. In the past 10 years, the only year when the Snake River Basin had a higher snow-water equivalent at this late a date was 1999.

“This is the wettest and latest winter we’ve had on Togwotee Pass, compared even to 1997 and 1999,” Beus said.

River flows have already peaked on the Snake River below Palisades Dam, which was 55 percent full Tuesday. On Sunday morning, Palisades reservoir releases peaked at 18,400 cfs and are currently being ramped down. Beus said he expects the reservoir to come close to filling this spring, but doubts that there will be excess water to release.

For rafting companies and whitewater enthusiasts, temperatures are expected to begin rising gradually this weekend and the long-term forecast calls for warmer weather into next week.

“If that scenario remains, that will likely be our peak for the year,” Beus said.

Beginning on May 16, a blast of warm weather sent runoff surging into the Snake’s tributaries, and on May 22 the Snake hit its 2008 peak of 15,555 cfs above Alpine. Beus expects the next peak will exceed those flows, but said the danger of flooding is decreasing because the amount of area that remains snow-covered is diminished.

“We have snow up high, but it’s limited in how warm it can get up there because of elevation,” Beus said. “A few weeks ago we had snow at low elevations, too, so we had a greater area exposed to melting.”

In 2007, the Bureau’s projected release schedule was abandoned in late summer and into the fall, as demand for water in Idaho forced water managers to increase releases substantially. Those fall releases drew criticism from fishing guides, who were impacted during the traditional peak of dry fly-fishing season. Beus said cool weather in Idaho has kept early-season irrigation demands moderate and the release schedule announced at a May 15 water-users meeting is still in effect.

“With the lateness of the season, it’s becoming extremely unlikely we would have to draft more than 200,000 acre feet out of Jackson Lake,” Beus said. “It might grow a little bit as we get later, but nothing like last year’s upside-down operation. When we get 100 percent full in Jackson Lake, we’ll be passing inflow. As we update the forecast process, we may be increasing releases before we reach full. We want to take a week to go from 400 cfs to 6,000 and not do it in a day.”