Northern Water has determined it is time to initiate the second spill operation this season at Lake Granby. Outlet releases are being increased throughout today until outflows reach 1,500 cfs. We will maintain this release until at least next Monday. We are watching the skies this week – rainstorms are in the forecast and a significant rainfall event might prompt us to boost outflows even more.
At Willow Creek Reservoir, our West Slope operators will allow the reservoir elevation to rise to 8,129 feet this week. The high runoff this year generated a lot of debris which is now floating on the surface of the reservoir. The operators will adjust both the river outlet works and the gates on the pump canal. Prevailing winds should then help force the debris to move to the northeast corner of the reservoir where it can be removed. Once this operation is complete, the reservoir will be returned to its normal operating elevation of 8124 feet.
2011 RUNOFF UPDATE
Showing posts with label Elevation. Show all posts
Showing posts with label Elevation. Show all posts
Monday, July 11, 2011
Tuesday, July 5, 2011
Granby Dam spillway water to taper off
We're continuing to reduce releases from Lake Granby this week. By Friday, water will no longer be going over the spillway; releases will only be coming out of the valves, which is where we normally make releases. We'll have 430 cfs coming out of the valves until re-evaluating the situation next week.
This spill was successful because it evacuated enough water so we could capture the peak inflow to the reservoir.
We expect to have a second spill as the reservoir approaches full capacity. It will be shorter and involve less water over the spillway. Operating the dam this way will allow us to gently fill the reservoir to the top while preventing the need to make large releases below the dam.
This spill was successful because it evacuated enough water so we could capture the peak inflow to the reservoir.
We expect to have a second spill as the reservoir approaches full capacity. It will be shorter and involve less water over the spillway. Operating the dam this way will allow us to gently fill the reservoir to the top while preventing the need to make large releases below the dam.
Friday, July 1, 2011
Willow Creek Reservoir elevation: Back to normal
After a couple of months of looking pretty low, Willow Creek Reservoir's elevation will start looking up.
The reservoir's elevation will start to rise in the next few days as we go back to more normal operations for this time of year. The elevation has been lower than the seasonal average because of releases, which since April 1 have equaled more than 106,300 acre feet - nearly two and a half times the amount that normally flows in.
In a typical year, Willow Creek's pump plant moves reservoir water to Lake Granby. But in this wet year, we knew Lake Granby wouldn't have room for that water, so we let it simply pass through Willow Creek Reservoir. There was so much Willow Creek water passing through that we had to keep the reservoir elevation much lower than usual so we could be prepared for heavier runoff peaks and help protect the channel downstream.
Now that the runoff is tapering, the risk of peaking events is significantly reduced and we feel comfortable letting Willow Creek Reservoir go back to its normal elevation. Over the next few days, it will gradually rise to 8,124 feet - about nine feet higher than it is today.
During this fill period, flows below the reservoir will be reduced, but once the reservoir reaches elevation, we will start passing inflows again.
This chart shows how Willow Creek inflows (red) compare to outflows (green) this year:
The reservoir's elevation will start to rise in the next few days as we go back to more normal operations for this time of year. The elevation has been lower than the seasonal average because of releases, which since April 1 have equaled more than 106,300 acre feet - nearly two and a half times the amount that normally flows in.
In a typical year, Willow Creek's pump plant moves reservoir water to Lake Granby. But in this wet year, we knew Lake Granby wouldn't have room for that water, so we let it simply pass through Willow Creek Reservoir. There was so much Willow Creek water passing through that we had to keep the reservoir elevation much lower than usual so we could be prepared for heavier runoff peaks and help protect the channel downstream.
Now that the runoff is tapering, the risk of peaking events is significantly reduced and we feel comfortable letting Willow Creek Reservoir go back to its normal elevation. Over the next few days, it will gradually rise to 8,124 feet - about nine feet higher than it is today.
During this fill period, flows below the reservoir will be reduced, but once the reservoir reaches elevation, we will start passing inflows again.
This chart shows how Willow Creek inflows (red) compare to outflows (green) this year:
 |
2011 Willow Creek Reservoir inflows (red) and outflows (green) |
Subscribe to:
Posts (Atom)