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chris
Site Admin
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Posted: May 21, 2007 Post Subject: Tuolumne river release schedule for 2007
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| Hetch Hetchy Water and Power have released the Tuolumne River release schedule for 2007. The Dreamflows copy is here.
Be sure to check back here (to this topic) from time to time for any changes and updates to the schedule, and news/releases on the Tuolumne generally.
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chris
Site Admin
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| Hetch Hetchy Water and Power reports as follows:
HHWP is initiating a 24-hr pulse flow today in the reach between Hetch Hetchy and Early Intake, and the high flow will then travel down to Don Pedro. The release at Hetch Hetchy will rise from 1500 cfs this morning to 3000 cfs and that will continue through about 8 am Tuesday, May 22. Around 8 am on Tuesday it will ramp down to between 1000 and 1200 cfs, and then will ramp down to between 200 and 400 cfs around noon.
There is a 4-5 hour delay between when releases change at Hetch Hetchy and when the water level changes at Lumsden. The flow at Lumsden will rise from about 2800 cfs to about 4300 cfs between 1 and 2 pm today, and it will recede gradually tomorrow sometime after noon to about 2300 cfs by dark.
This release is being made for ecological and geomorphologic purposes and to support data collection activities by scientists at Yosemite National Park.
Releases at Holm and Kirkwood powerhouses will supply recreational flows in the range of 1800-2400 cfs from Wednesday through Friday, and at least the standard 1100 cfs flows at Lumsden will be occurring during the 9 am to 1 pm time period from Saturday the 26th through the end of May.
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chris
Site Admin
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| Hetch Hetchy Water and Power reports as follows:
"River folks -
Inflow went down due to the cool weather last weekend, and is now coming back up. Cherry and Eleanor are done spilling, but Hetch Hetchy is being actively managed and changes are frequent.
Our schedule calls for 5-hr releases today (Friday) through Monday because it is a holiday weekend. In addition to the releases from Holm PH, we will also have releases at Early intake increase from 300 cfs to 900 cfs around 7 am tomorrow (Saturday) and be constant through at least Monday. Rock Garden should be less rocky......
Normal 4-hr releases are schedule for Tuesday - Thursday of next week, May 29-31. There are also scheduled releases on Friday and Saturday, June 1-2, but not on Sunday the 3rd.
I'll let you know when releases at Intake begin to fade."
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chris
Site Admin
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| Hetch Hetchy Water and Power reports as follows:
"With the even warmer weather, inflow at all three reservoirs has increased, and there has been a significant increase at Hetch Hetchy. Cherry and Eleanor are being held near the top, and releases are being made to control spill magnitude at O'Shaughnessy.
Releases below Holm PH will range from 800 cfs during non-boating hours to 1000 cfs between 7 and 11 am for the next 2-4 days.
Releases below Early Intake have rose from 800 yesterday to about 900 cfs today, and will rise to about 1700 cfs tomorrow.
These higher flows will hold through at least Thursday. Please stay safe."
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chris
Site Admin
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| Hetch Hetchy Water and Power reports as follows:
"Snowmelt inflow is backing down in spite of the high temperatures - we are about done with the higher flows for this year.
Releases from Holm Powerhouse will be dropping Thursday through Saturday to 300-500 cfs during the hours that do not have scheduled releases (7 - 11 am).
Flow below Early Intake has dropped from 1,900 cfs earlier today to 1,200 tonight, and will be between 1000 and 1400 cfs tomorrow as spill starts at Hetch Hetchy. Flow will drop between 100 and 200 cfs per day for the next 5 days due to less snowmelt inflow and temperature effects."
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chris
Site Admin
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| Hetch Hetchy Water and Power reports as follows:
"Only Hetch Hetchy is still in mild spill, and I am expecting spill to stop by the end of Saturday. Flow below Early Intake will be about 1200 cfs on Saturday, combining with about 700 cfs from Cherry during non-boating release hours, and 950 cfs during boating hours. Flow at Lumsden will be ths sum of the two, with a 2-hr lag for the changes at Cherry to get there.
However, due to some maintenance next week, the Sunday flow below Early Intake will be stay at about 1100 cfs all day. The Sunday release at Holm PH will be about 400 all day, which adds up to about 1500 cfs at Lumsden.
Enjoy your weekend."
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chris
Site Admin
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| Hetch Hetchy Water and Power reports as follows:
"Between the cool weather and the end of the remaining, high-elevation snowpack, extra releases at Early Intake will be stopping and we will be back to the flow schedule outlined in the Final flow calendar that was released earlier.
Holm PH will be making the normal recreation releases between 7 and 11 AM for the next week, and Sunday the 10th is also a release day. Releases from Holm will be in the 400 to 600 cfs range the rest of the hours of the day as it is operated to meet electrical demands.
Releases at Early Intake have been 900 cfs plus spill from Hetch Hetchy, but flow below Intake decreased to about 425 cfs today at 11 am and will taper down to 350 cfs by tonight. Releases may decrease on Sunday at 8 am to 125 cfs, but they may also stay at 350 cfs through Monday morning - depending on how long the current cool temperatures continue.
After Monday or Tuesday, we will reach "summer" conditions, and after one last "flow bulletin" early next week, I will be in touch with you only to inform you that an unexpected situation has occurred."
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chris
Site Admin
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| Hetch Hetchy Water and Power reports as follows:
"A combination of the cool weather and 55% of normal snowpack has dropped inflows to low levels here in the 2nd week of June. There will not be extra releases for the rest of the summer beyond the normal minimum streamflow releases that support the aquatic ecosystem on the mainstem of the Tuolumne below Hetch Hetchy and Early Intake.
There will continue to be regular releases for river recreationists as described in the schedule we jointly developed and was released earlier.
This is my last note for several months due to the predictablity of the releases. If we have equipment difficulties that affect releases, I will let you know as soon as I can. I will also be back in touch when more is known in terms of releases after September 3. Have a great summer, and please be safe."
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chris
Site Admin
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| Posted: Jul 26, 2007Post Subject: Special Release
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| Hetch Hetchy Water and Power reports as follows:
"River Folks - The SFPUC Natural Resources Division has contracted with an aerial photography firm to make a high-resolution survey of the Tuolumne between Don Pedro and Hetchy Hetchy, Lake Lloyd, and Lake Eleanor. The photos are of greatest use if the water is shallow, thereby exposing the various channel bars, riparian vegetation, and boulder/gravel areas.
After conferring with the commercial rafting groups, we are planning to modify the flow pattern on Monday, August 6. Instead of the normal 7-to-11 am release from Holm Powerhouse on Cherry Creek, the release will be from 7:30 to 10:30 am on August 6. Please plan your trips accordingly - those downriver will find the water arriving a little late and ending a little early. People doing 1-day trips will need to avoid delays. Be aware that you may see and hear a fixed-wing aircraft in or near the canyon.
There is a possibility the weather will not cooperate and clouds will be a problem on August 6. If that occurs, the short release will still occur and I will be back in touch with a date later that week or during the subsequent week when we will try again.
Hope everyone's summer is going well."
I've updated the Tuolumne Schedule Page accordingly.
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chris
Site Admin
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| Hetch Hetchy Water and Power reports as follows:
"Folks - I sent you a note last week to notify you all that the release on Aug. 6 would be an hour shorter due to our plans to do an aerial photography mission on the Tuolumne.
I wanted to let you know that the August 6 date ran into problems, and I have changed the photo day from Aug 6 to Sunday, Aug. 12. There is no release scheduled for that Sunday - it is one of our maintenance days. We will also be flying upper reaches on Monday the 13th, so you may see a small aircraft enroute at some point."
I've updated the Tuolumne Schedule Page accordingly
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chris
Site Admin
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| Hetch Hetchy Water and Power reports as follows:
"Hello all - I have had several inquiries as to possible additional dates past Sept. 3 on which HHWP could provide scheduled releases. After extensive power demand projections and evaluation of forward energy prices to determine costs to the SFPUC, we propose to add Friday and Saturday of the two weekends after Sept. 3:
7 - 11 am releases of approx. 970 cfs from Holm PH: Sept. 7 & 8, and Sept. 14 & 15.
In addition to these additional four days that will have the usual 1050 - 1100 cfs at Lumsden, I expect the following Sundays (Sept. 9 and 16) to have between 700 and 800 cfs during most of the daytime. Trips that are past Rock Garden would have water that might be suitable to complete the trip, depending on boater preference and bivouac location.
I expect 700-800 cfs will be a typical flow rate during the many of the September weekdays as well because the generated power is used to meet a portion of municipal demand in San Francisco, Modesto, and Turlock.
Due to planned maintenance, releases from Holm PH will be greatly reduced after October 15".
I've updated the Tuolumne Schedule Page accordingly.
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chris
Site Admin
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| | Hetch Hetchy Water and Power expressed the scheduled releases in a slightly different way, and also provided more detail. The Tuolumne Schedule Page shows the current schedule. Note that the salmon-colored entries aren't official releases, just best-faith predictions.
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