Reclamation to Conduct Tests at Yellowtail Afterbay

Montana Area OfficeBillings, MontanaMedia Contact: Paula A. Holwegner (406) 247-7300 For Immediate ReleaseReclamation to Conduct Tests at Yellowtail AfterbayDuring the daylight hours of May 5, 6, and 7, 2009, flows in the Bighorn River will fluctuate as the Bureau of Reclamation tests new gate automation equipment at the Yellowtail Afterbay Dam. Flow rates in the Bighorn River can be expected to vary between 1,500 cubic feet per second (cfs) and 4,500 cfs for very brief periods, during which the U. S. Geological Survey will be measuring flows in the river. The tests are being closely coordinated with the Montana Fish, Wildlife, and Parks to minimize fishery impacts. Bighorn River recreationists are cautioned to be aware of changing flow conditions during this time.Reclamation is the largest wholesale water supplier and the second largest producer of hydroelectric power in the United States, with operations and facilities in the 17 Western States. Its facilities also provide substantial flood control, recreation, and fish and wildlife benefits. Visit our website at

Flow to increase to 3,000cfs

With the lake at its highest level on this date since the dam was closed, with snowpack at 108%, with inflow predictions looking pretty solid, and the need for reduce the lake elevation from its current 3,627.6ft to 2,624ft for some repairs, Reclamation has decided to increase discharges to the Bighorn river starting Wednesday, April 8th.Starting Wednesday, flows will increase from 2,450cfs to 2,750cfs.The following day, Thursday, flows will again be increased from 2,750 to 3,000cfs.Flows should remain at 3,000cfs or higher until runoff requires additional discharges.

April 14 – 16 update

As of today April 3, it looks like the BOR/USGS work at the Afterbay will NOT involve bouncing the flows around on April 14-16. Some testing may still occur, but it shouldn’t affect river releases. However, check in at this site for the latest up to date information, as conditions and situations may change.

Spring Planning meeting update

Winter lake levels have rarely been this high the first week in April, but with river releases below minimums and decent inflows, this is no surprise.BOR’s proposed operating plan shows flows of at least 2,850cfs at the end of April. However, a couple of things on the horizon may make April interesting for BOR and river users.You’ve heard about the new gaging equipment they’re working at the Afterbay, right? Supposedly, BOR was going to bounce flows around on April 14 and 15 to do some calibration work. Word had gone out from BOR last month that testing and calibration was to occur on April 14th and 15th. Dan Jewell is now saying nothing concrete has been scheduled, and he’ll give at least two weeks noticed when something is scheduled. As soon as FOBR can figure out exactly what’s going on, we’ll post it.Secondly, the dam wall is seeping, which we’re told is entirely normal. The problem is that seeping water high up on the downstream side freezes and makes for some nasty, nasty icicle projectiles when they breaks loose. This problem is compounded by power lines attached to the dam, which the falling ice can easily take out. Long story short, they need to lower the lake level to just below 3,624ft to get some repair work done, and the window of opportunity grows smaller with every passing day. One would think if BOR wants to attempt repairs this spring its going to have to happen very, very soon.Summary: As this is being written, the lake level stands at 3627.60, having risen about a half foot with a flush from Boysen several days ago. The forecast show some moisture for the month of April. BOR’s proposed operating plan shows April end-of-month river discharges at 2,850cfs. Considering all this, plus the dam seepage, and the fact there’s little available storage in the reservoir, one would have to assume increased releases are coming sometime this month, and probably sooner rather than later.