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chris
Site Admin
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| | I asked for it but haven't heard back yet. Will publish soon as it arrives.
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chris
Site Admin
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| Hetch Hetchy Water and Power reported as follows:
"Hello river users –
Inflows continue to taper off in spite of the heat as the snowpack diminishes. It is likely that this week will see the last of the excess flows from Cherry, and the last of the spill form Hetch Hetchy. The exact timing on the recession is always approximate, however.
Tuesday (tomorrow) will see the first day where Holm PH runs a standard 4-hour schedule that accommodates rafting, and the rising water will arrive at Meral’s at about 9 am. Releases at Intake will be around 1100 cfs for all but the 10 to 11 am hour, when they will fall to about 500 cfs as some power house operations are done. Rafters will notice a 600 cfs drop from noon to 1 pm at Meral’s, and that dip will travel down the river during the day, followed by the return. But be aware that lower flows are following the 4 hour pulse as it travels down the river, just like on normal summer days. Late launches at Meral’s won’t be fun.
Wednesday will see flows at Meral’s between 2100 and 2300 cfs. Thursday should see flows at Merals of 1700 to 1900 cfs.
We will start shifting over to the 4-hour release from Holm PH around Friday and the weekend as other flows decrease. Meral’s Pool launches between 9 am and 1 pm will soon be the only time there will be adequate boating water."
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chris
Site Admin
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| | The 2010 Lower Tuolumne and Cherry Creek release schedule is posted here
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mikes
Member
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Posted: Jul 13, 2010 Post Subject: thanks chris
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chris
Site Admin
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| Hetch Hetchy Water and Power reported as follows:
"Hello river recreationists,
As most of you have noticed, flows have been on the way down and we will begin the regular summer schedule next week. Dreamflows currently has flow at Meral’s near 2,000 cfs. Flow rates there will continue to drop as spill at Hetchy Hetchy decreases. No more spills will be seen from Cherry or Eleanor. Starting Sunday, we will be closer to the usual rafting schedule with some slight variation. Here is the daily summary:
Friday -- ~1600 - 1700 cfs at Meral’s around the clock. Cherry Creek from Holm PH to the confluence will be ~600 cfs, and ~1500 at the confluence
Saturday – 1600 -1700 cfs at Meral’s around the clock. Cherry Creek from HPH to the confluence will be be ~700 cfs, and ~1600 at the confluence
Sunday and Monday – From about 9 am to 1 pm, flows at Meral’s flows will be in the 1100 to 1400 cfs range. There will be about 850 cfs below HPH during the 4-hour rafting release time. There will be additional releases at Intake before and after the rafting release at HPH, but flows at Meral’s are likely to be less than 600 cfs.
Tuesday - Regular rafting flow schedule and Project releases with 1100 cfs from HPH from 7 to 11 am, 9 am -1 pm pulse at Meral’s.
Wednesday the 21st is NOT a scheduled rafting day. This will be the first non-boating day of the season.
Thursday will be back to the regular summer boating schedule.
It has been a great boating spring, and an interesting year to try to forecast. There will NOT be any further recreation conditions updates due to the return to the regular summer conditions as outlined in the calendar I emailed last week. The calendar has also been posted on Dreamflows – thanks, Chris!
Enjoy the summer and please recreate safely!"
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chris
Site Admin
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| Hetch Hetchy Water and Power reported as follows:
"I wanted to send a reminder that Sept. 1 and 2 are days where no flows are scheduled. On Wednesday and Thursday, I expect releases at Holm to be in the 100 cfs range, so coupled with flows above Holm and the 155 cfs flow above Intake, I expect a pretty low total of 300 cfs or so at Meral’s.
Lots of requests are coming in for clarification of what Holm releases will be after Sept 6, the last day on the flow calendar for this summer. Releases from Holm will stay low from Sept 7 through 13 – the 300 cfs or so listed above. From Sept 14 through the end of the month, the general plan is to release 150-300 cfs during daylight hours below Holm. Water will be used during daylight times for economic efficiency, and exactly how it will be shaped is not clear. Once that pattern starts, it is likely to be repeated through the month with only small reduction for weekends due to decreased load.
At this point it looks like October would be the same, but it is a bit early to know for sure.
The reason for this schedule is that the cool weather (up until this week) in the Bay Area has depressed water use to the point that the reservoirs there are too full and need to be used. That means we have to deliver less water from HH and consequently will generate less power on the Hetchy side. We therefore need to use Cherry Lake water to make up the shortfall, but we don’t need so much that we can bring flows up to the regular rafting amounts.
I know that you understand that this estimated flow is not a commitment and will be modified if maintenance schedules require it. If I learn that power needs will cause us to either go up or down significantly, I will let you know as much in advance as possible."
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chris
Site Admin
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| An alternative way of presenting the flow information in the previous post is: "After Sept 14 (i.e. from Sept 15 onward) expect fluctuating flows from 6am to 10pm with an AVERAGE of 150-300 cfs. Look at the graph on Monday and expect the same general kind of behavior for the rest of the week, except flows on the weekend may not be quite as high. Be philosophical if plans change."
HHW&P blessed the above interpretation, and added: "Here is a quick update already for the Sept 1 & 2 dates. Due to some relay testing work, there will be about 475 cfs being released from Holm between about 8 am and 5 pm. So there will be at least a little water on those dates when I thought it was going to be very low."
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Edited once. Last edited by chris Aug 26, 2010.
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