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chris
Site Admin
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Posted: Apr 25, 2006 Post Subject: Upper Upper Tuolumne/Cherry Creek flow information
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| The San Francisco Public Utilities Commission reports as follows: "At 10:00 today, we will be increasing the release below Hetch Hetchy Reservoir from about 750 cfs to 1500 cfs. At approximately 1:00 today, we will be increasing the releases below Hetch Hetchy Reservoir to 3000 cfs. A release of 3000 cfs from Hetch Hetchy Reservoir will be maintained through the month of May.
On Monday, May 1, we will be increasing the flows below Cherry Reservoir to about 300 cfs. We will maintain this release through the month of May.
Depending on temperatures, we will begin spilling at Eleanor within the next day or so."
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chris
Site Admin
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| | The San Francisco Public Utilities Commission reports again as follows: "HHWP is reducing the total release below Hetch Hetch Dam by 500 cfs from 3,000 cfs to 2,500 cfs. The release will stay at this level through middle of next week."
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chris
Site Admin
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| The San Francisco Public Utilities Commission reports again as follows: "The weather has done a quick transition into summer, and the warm temperatures are causing significant inflows due to accelerating snowmelt. Reservoir storage is increasing rapidly.
We expect to increase releases from Hetch Hetchy on Monday, May 1, from 2,500 cfs to between 3,000 and 3,500 cfs.
As previously planned, we will start a release from Cherry Reservoir on Monday of 300-400 cfs.
Eleanor Reservoir has reached the spillway, and the 600 cfs release has increased to 700 cfs today, and will continue to go up with uncontrollable spill.
Please continue to review the USGS gages posted on the internet to stay abreast of flow conditions."
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chris
Site Admin
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| The San Francisco Public Utilities Commission reports again as follows: "Because of the warm weather, inflows to the reservoirs are on the rise, and Lake Eleanor is spilling. To limit upcoming spills, HHWP will increase the total release below Hetch Hetchy Dam from 2,500 cfs to 3,200 cfs starting today, Monday, MAY 1. Also, a release of about 400 cfs below Cherry Dam will begin today. Holm PH will continue to discharge about 1000 cfs, and Kirkwood spill will continue to be about 600 cfs.
These releases will continue through the May 6 weekend unless you are otherwise notified."
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chris
Site Admin
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| The San Francisco Public Utilities Commission reports again as follows: "The weather has cooled a bit and that will last through the weekend, but the warm temperatures of the last 6 days are causing inflows to stay high. Reservoir storage is increasing but less rapidly than last week.
We expect to maintain the current releases at the following sites through May 15:
Hetch Hetchy will remain between 3,200 and 3,500.
Cherry Reservoir will continue at 350-450 cfs.
Eleanor Reservoir is spilling about 1,350, and that will decline slightly with cooler temperatures."
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chris
Site Admin
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| The San Francisco Public Utilities Commission reports again as follows: "Tuolumne River Recreational Users:
Today (Monday) we are decreasing the valve releases at Cherry from 400 to 10 cfs, and at O'S from 3,390 to about 3,000 cfs. Holm and Kirkwood powerhouses are scheduled at full load round the clock.
These releases will continue through Friday, May 12 unless you are otherwise notified."
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chris
Site Admin
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| The San Francisco Public Utilities Commission reports again as follows: "Rafters and other interested parties -
Per your earlier notice today, we have reduced releases at Cherry by from 400 cfs to 15 cfs, and at Hetch Hetchy from 3400 cfs to ~3,000 cfs. Eleanor is spilling about 1500 cfs and Holm PH is releasing about 950 cfs. About 700 cfs is spilling at Early Intake from Kirkwood PH. This flow situation will continue until Saturday morning at 0600, 5/13.
On Saturday morning at 0600, in support of a geomorphology study on the reach below Cherry Dam, we are ramping up the flows to a full valve release from the dam. By 6 pm on 5/13, we will be releasing approximately 4,600 cfs, and this release will last until 3 pm on Sunday, 5/14. By 1500 hrs on Monday 5/15 the release will be back down to 200 cfs. Flows from Eleanor, Hetch Hetchy, and Holm PH will remain mostly unchanged during this time (total of ~5,400 cfs), and after the geomorphology study the flows should be as they are today through Thursday, 5/18.
On the following weekend flow will also change due to the second phase of the geomorphology study, but high releases will NOT occur on the weekend. We will ramp down HH releases starting Friday, 5/19 at 1600 hrs, and releases on Saturday 5/20 will go from 1500 cfs at 0700 to 185 at 1600 hrs and remain there until Monday 5/22 at 1700 hrs. Holm PH, Kirkwood, and Eleanor releases will stay the same as they are now (total of ~3,100 cfs). At that point releases will ramp up to ~6,400 cfs by Tuesday 5/23 at 1800 hrs. The release will stay high until 1600 hrs on Thursday, 5/25, at at that point they will return to the current 3000 cfs, and conditions should be approximately what they are now for the weekend of 5/27-28.
I am concerned that the high release from Cherry this weekend 5/13-14 will make boating dangerous, so please use caution in scheduling trips."
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chris
Site Admin
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| | The San Francisco Public Utilities Commission reports that they will ramp up releases from Cherry Dam to support a geomorphology study. Releases will go from 400 to 4700 cfs on Saturday, and while Saturday boaters who launch before noon will be OK if they do not linger, two-day trips (if there are any) will get very high flows by Saturday night. They will maintain these flows on Sunday until 5 pm, and then ramp down. Since the flow at Meral's Pool is already about 7500 cfs, the additional 4000+ cfs will bring the total to 11,500 or 12,000 cfs. The river is considered VERY DANGEROUS at this flow.
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chris
Site Admin
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| The San Francisco Public Utilities Commission reports again as follows: "River users - The hot weather has greatly increased the inflow into Hetch Hetchy, and to avoid early, large spills, the release from HH Res. will increase at 3 pm today (Monday) from 3,150 cfs for between 4,800 and 5,500 cfs, with a target of 5,000 cfs.
The test flow releases from Cherry Res. have stopped, and the release there is 150 cfs and will hold there through 5/21. The Eleanor spill is cycling between 1400 and 1600 cfs, and Holm PH is releasing about 975 cfs. About 500 cfs is spilling from Kirkwood PH at Early intake, and the combined flow below EI is about 4,000 cfs now and will increase approximately 2,000 cfs with the increased release from Hetch Hetchy today.
The higher release at O'Shaughnessy will continue through Friday at noon, and flows will then ramp down in 4 hour increments and reach 200 cfs release by 4 pm, Saturday 5/20. As per my earlier memo, they will stay low until 4 pm Monday, 5/22, and then will ramp back up to about 6,400 cfs on Tuesday, 5/23, and hold at that level until 3 pm on Thursday, 5/25. Releases will then be reduced to between 3,500 and 5,500 cfs and will hold there until spill starts.
Please be aware of high water hazards in the reach between O'Shaughnessy and Early Intake at these high releases.
My thanks to everyone who helped with safety notifications and signage and web site postings during the test flow release from Cherry Reservoir this past weekend. I hope that boaters were spared getting down to the river and finding it unsafe for their skill level, or having it come up while they were enroute."
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chris
Site Admin
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| The San Francisco Public Utilities Commission reports again as follows: "Hello River Folks - Cooler air temperatures should slow snowmelt over the next few days, so inflows and tributary flows may decline a bit by the end of the weekend and early next week. NWS rain forecasts are for only a few tenths, so we don't expect more than gray skies and some scattered showers.
As per my last memo, this weekend we are cutting back the release from Hetch Hetchy to support a river channel study. We are also increasing the Cherry release to delay spill, and those changes will affect Saturday morning Merals flows. Dreamflows is showing a mean of 11,000 cfs at Merals today, and that should decrease about 2000 cfs by 9 am Saturday due to a decreased HH release. By 6 pm Saturday, the HH release will drop another 1500 cfs.
That Merals flow of about 7,500 cfs will continue from Sunday AM through Tuesday, 5/23, 10 am. Flow will then increase to above 13,000 cfs due to the second part of the river channel study and a large release from Hetchy Hetchy. The high flow will last all day Wednesday and Thursday. By Friday 5/26, flow will return to between 9,000 and 12,000, depending on weather and inflow conditions.
Please use great caution during the high flow period Wednesday and Thursday, and check Dreamflows:
http://www.dreamflows.com/graphs/day.090.html
If the cooler weather slows down the melt, and coolness lingers, releases should continue to be at or below the current rate. If hot weather returns, releases and spill may push flows above 11,000 cfs. We are doing our best to smooth things out for recreationists, but the choices are narrowing as Cherry and HH Reservoirs approach their spill crests. I will keep you informed."
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chris
Site Admin
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| The San Francisco Public Utilities Commission reports again as follows: "Hello River Folks - Thank you for your patience during our changing and high flows to support some mandatory environmental (geomorphology) studies this week.
Today at 4 pm, the HH release will decrease from 6,500 to approximately 3000 cfs, and it will go to 1500 cfs at 7 am on Friday morning and then hold steady throughout the weekend and following week. There will continue to be about 700 cfs spill at Early Intake from Kirkwood PH.
There is about 800 cfs spill from Eleanor, about 10 cfs from Cherry, and Holm will be at about 950 cfs during daylight hours, plus tributary flow. Eleanor will decrease to about 500 cfs on Tuesday and then slowly decline, but otherwise flows will be fairly stable.
The middle and south Forks continue to put in water, estimates range from 500 to 1000 cfs.
Subtracting the changes from the current Dreamflows estimate, I think flows at Lumsden will settle out at between 4500 and 6500 cfs after about noon tomorrow (Friday), depending on weather conditions. Continued cool weather through Wednesday and no precip is in the forecast
Have a great holiday weekend."
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chris
Site Admin
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| The San Francisco Public Utilities Commission reports again as follows: "Hello River Folks - With the warm weather (80+ at 8,000 ft), inflow into Hetch Hetchy is increasing fast, and while increases into Eleanor and Cherry are only moderate due to their smaller size and less snowpack left, they are just about full and will soon start to spill.
I am increasing the release at HH today. I will add another 1400 cfs to the current release of 1600 cfs - a total release of 3,000 cfs will be occurring by 1 pm today. 700 cfs is being released at Kirkwood, and that is unchanged. Only minimum streamflows are being released from Eleanor and Cherry, but Eleanor will start spilling about 1000 cfs by Sunday morning. Holm PH will continue to release about 950 cfs during daylight hours, and that is unchanged.
The Dreamflows site has been intermittent because of problems with the USGS stream gages. The current estimated flow is about 4,500 cfs, and I expect it to increase 1400 cfs by 6 pm today (Friday) due to the HH release. I expect another 1000 cfs to arrive at Lumsden from Eleanor by Sunday morning, for a total of about 8000 cfs for Sunday boating.
I expect that level to hold through next week, and I will let you know if HH inflows require me to make further increases in the release and when Cherry starts to spill.
be safe"
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chris
Site Admin
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| The San Francisco Public Utilities Commission reports again as follows: "River Folks - The hot weather is continuing to increase inflows to HH, Cherry, and Eleanor. Both Eleanor and Cherry are spilling, so what comes in has to go out. I expect Eleanor inflow to start decreasing by Friday, and for Cherry inflow to start decreasing by the middle of next week (June 14 or so). HH is 92% full, and inflows will stay above 7,000 cfs at least through June 15.
I started a release at Cherry of 500 cfs on Saturday, and that release/spill will go up to 2000 cfs by noon today. Eleanor is spilling about 900 cfs. The current 3,000 cfs release at HH will increase to 4,500 cfs by 4 pm today.
The Dreamflow site shows about 7,000 cfs now, and with the above changes, I expect about 10,000 cfs at Lumsden. This flow rate should continue through the week, or until additional releases have to be made at HH to control the rising water level. I cannot accurately predict when HH will start to spill, but when it does it will add another ~3,000 cfs to the flow at Lumsden.
Next weekend's flow is difficult to predict, but I suspect it will still be in excess of 10,000 cfs and as high as 15,000. Please take those high flows into account when making plans, and I will communicate again around Thursday, 8 June."
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chris
Site Admin
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| The San Francisco Public Utilities Commission reports again as follows: "Inflows have surged again today, with over 9,000 cfs coming into Hetch Hetchy Reservoir. Projections showed that Hetchy would start spilling on Thursday at the current release rate. Spill is already occurring at Eleanor and Cherry.
After conversations internally and with Marty at Sierra Mac, we are going to try to keep control of HH to allow boating launches on Friday the 9th and Saturday the 10th. Sunday the 11th is uncertain and will depend on inflows. I will know more about Sunday conditions on Friday the 9th.
Tomorrow (Tuesday the 6th) morning at 7 am we will go to about 8,000 cfs release from Hetchy, and my estimate is that there will be about 14,000 cfs at Lumsden as a result. On Friday the 9th at 7 am, we will cut back to about 4,000 cfs. That reduction should appear at Lumsden about noon. We will hold that into Sunday the 11th, but I expect HH to start to spill by midday if current inflow projections hold. Valve releases will then have to be increased to control flow depth over the gates. I expect the release/spill on Sunday to climb to 7,000 cfs by 9 pm. Please consider Sunday launches for 2-day trips very carefully.
On Monday the 12th, we will again go to 8,000 cfs release from Hetchy. While spill from Cherry and Eleanor is expected to decrease somewhat, I would expect flow at Lumsden to be 13,000 cfs or greater through Thursday the 15th.
If conditions permit, I plan to again reduce releases on Friday the 16th to produce flows of 10,000 cfs or less for the weekend. Predictions are less sure that far out, so we will try to firm this up Monday the 12th.
DISCLAIMER: Predictions of inflow magnitude have error, and while Hetch Hetchy operations will do their best to follow the schedule outlined above, I CANNOT GUARANTEE these Lumsden flow magnitudes. Please use caution."
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chris
Site Admin
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| The San Francisco Public Utilities Commission reports again as follows: "River Folks - Both the National Weather Service forecast (warmer weather plus thunderstorms in the high Sierra) and the River Forecast Center forecast (larger inflows to Hetch Hetchy) have dashed my hope of being able to provide a window this coming weekend for boating. I will not be halving the release on Friday morning (as per yesterday's 4:30 pm email) at Hetch Hetchy to accomodate rafting Friday-Sunday because spill would start by noon Saturday even without thunderstorms.
HH has a mere 15,000 AF of storage space in it at this moment, and inflows today and for the next 4 days are forecasted to be 18,500 AF, 20,000, 21,000, 21,000, and 20,000 AF/day. I have to deal with every day's inflow on that day or the unused amount pushes over into the spillway and creates spills in excess of 10,000 cfs at the dam.
Flows at Lumsden will stay in the 13,000 - 15,000 cfs range through approximately Thursday, June 15. It is possible that we might be able to reduce releases next weekend, but I will not know until approximately Monday the 12th.
My apologies for the hopeful note last night, but this morning's forecasts moved the issue out of my control. I will let you know when I see conditions improving."
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Edited twice. Last edited Jul 27, 2006.
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