Snake River Jackson Hole Wyoming

Runoff 5/4/2015

This year’s spring runoff on the Snake River and it’s tributaries  has been really unpredictable; with the below average snowpack and warm temps this summer season on the area rivers, creeks, lakes and streams should be very interesting, to say the least. The Snake River water’s primary use is for irrigation in Idaho so we’re at their mercy for the way the water flows are managed, typically. That being said, the folks at the Bureau of Reclamation, who manage the dam releases have a very difficult task at hand. They have a mind boggling equation to solve which factors in, but not limited to; weather forecasts(future, present and past), snow pack, snow melt, irrigation needs, min flows to protect the trout and  flood control just to name a few.

See the article below that illustrates this point at hand.

Early Snake runoff getting used up

POSTED: TUESDAY, MAY 5, 2015 4:30 AM
By Mike Koshmrl Jackson Hole Daily | 0 comments

“Snake River water managers say record-setting early agricultural demands in eastern Idaho had the melting watershed in Wyoming running at a deficit until this weekend.
The spring melt is on, and runoff is 10 days to two weeks ahead of normal, but drawdowns from Palisades Reservoir had through Sunday exceeded the snowmelt feeding the creeks, rivers and lakes of the Snake watershed, said Mike Beus, water operations manager for the Bureau of Reclamation’s Upper Snake River field office.

“Kind of our big problem is that runoff is two weeks early and demand is running four weeks early,” Beus said Monday.
“Systemwide we were just holding our own yesterday after using a lot of water the past several weeks,” Beus said.
In the agricultural region around American Falls Reservoir crops are already planted in the parched ground, and the result was the “earliest” date Beus had ever seen a substantial irrigation demand. To accommodate that, releases from Palisades have exceeded 12,000 cubic feet per second since late April. The demand could have implications for releases at Jackson Lake and flows on the Snake River this summer and fall, though Beus said it’s too early to get into specifics “Jackson Lake, Palisades and American Falls are tightly connected,” he said, “and while we’ve been filling Jackson Lake slowly we’ve been using water from Palisades and American Falls. “American Falls is still going down, but Palisades made the corner and is probably going to fill a little bit,” Beus said.

On Monday, Jackson Lake’s 847,000 acre-feet of storage space was 86 percent filled, which well exceeds the average for the first week of May. Typically the dammed lake is barely more than half full at this point in the spring, Bureau of Reclamation databases show. Flows out of the dam will likely hold steady at 550 cfs — the winter rate of discharge — until the lake fills completely, Beus said.
It’s expected Jackson Lake will fill by late May. High “flood” flows below the dam this spring are unlikely, Beus said. The bureau’s annual Jackson meeting, at which Beus presents stream-flow forecasts and projects Jackson Lake and Palisades operations, has been scheduled for 7:30 p.m. May 13 at the Antler Inn.”