June 28, 2017
It looks like the big runoff is winding down. But it's not entirely done. The Bureau of Reclamation is on the verge of filling Jackson and Palisades reservoirs. This morning Jackson reservoir was at 99% with less than 10,000 acre-feet left to fill. The Bureau anticipates filling in the next few days. Palisades reservoir is at 98% and has only 27,000 acre-feet of empty space left. The Bureau anticipates it will fill in the next few days. American Falls is full and passing inflow, and the Bureau is still spilling flood control water at Milner - although that probably won't last longer than a few more days. In the meantime, we continue to accomplish recharge using our natural flow recharge permit.
The hydrograph below is the Snake River at Flagg Ranch, upstream of Jackson reservoir. What this graph tells me is that we're about two weeks ahead of average natural flow. Normally our natural flow lasts until the first week of July. This year I believe we might make it past our peak irrigation demand (which ends when we stop irrigating grain).
UPDATE: June 20, 2017
As you can see in the graph below, Palisades is continuing to fill rapidly. As of this morning, Jackson is at 96% and still rising, Palisades is 90% and rising, and American Falls is at 100% and passing inflows.
June 15, 2017 - Will Palisades Fill?
That's a question we get almost every day. The short answer is that we believe it will, despite this week's increase in spill from the reservoirs. The Bureau of Reclamation is still confident that there is plenty of water left in the remaining snow pack to fill Palisades and Jackson Reservoirs. As of this morning, Jackson is at 92%, Palisades is at 84%, American Falls is at 100% and the Bureau is again releasing water past Milner for flood control.
I anticipate we'll have a better-than-normal natural flow supply, possibly even lasting through our peak irrigation demand.
Water / Snow Report
January 10, 2017 - As of this morning, Jackson Reservoir is at 64% full and is filling quickly. It will continue to fill until it hits 75% where it will remain to provide flood control space until Spring.
Palisades Reservoir is at 31% full and is filling at about the same rate as last year.
American Falls Reservoir is 56% full and is filling faster than normal.
At the rate American Falls is filling, I suspect outflows from Palisades may be decreasing soon in order to avoid spilling water past American Falls.
Our snow pack is looking good, but it is still early in the season to be predicting our water supply for the upcoming season. We currently have 131% of average Snow Water Equivalent (SWE) for the date and 157% of average precipitation (i.e. inches of snow) for the combined watersheds above American Falls. While we would need 150%+ of SWE for the season to fill the reservoirs, we don't need full reservoirs to have a sufficient supply (though it really helps). If we have 'normal' precipitation for the rest of the winter we should have a sufficient supply.
Upper Snake Teacup
