| |
chris
Site Admin
|
Posted: May 6, 2009 Post Subject: Tuolumne - Lower and Cherry Creek flows
|
|
| Hetch Hetchy Water and Power reports as follows:
"River folks -
The big storm this past Friday-Saturday put 2.5 - 3.5 inches of rain up to about 9000 ft elevation in about a 12-hr period, and the river response was immediate - about 6,000 cfs was estimated by Dreamflows at Merals Pool on Saturday at noon. I know that lots of folks had to give up their plans.
Although the runoff from the rain has decreased, I am seeing snowmelt starting due to the warm sunny weather, and it is supposed to be even warmer for the next 3 days. Runoff has stopped decreasing, and Dreamflows reports 4500 cfs at Merals. The signal has been noisy due to a gaging station malfunction, but partial repairs were made by HHWP staff today, and the USGS will be on site to fix that tomorrow.
However, as per the schedule I released earlier and in keeping with multi-agency research planning, the release from Hetch Hetchy is going to increase 2000 cfs by 5 pm tomorrow (Thursday). I expect this additional release to push the flow at Merals Pool back up and over 6,000 cfs. I expect this high flow to continue through the weekend and through Wednesday, May 13.
I plan to reduce releases from Hetch Hetchy on Thursday May 14 to try to get flows at Merals Pool down below 4500 cfs again for Friday - Sunday. Weather, research findings, and other unknowns may prevent that, but I will let you know by Wednesday the 14th at 5 pm if conditions change and I cannot meet that target.
Please recreate safely and be careful."
This release schedule applies. I believe the 2000 cfs Bruce is referring to in his message works as follows. Today (Wed) the release from Hetch Hetchy was 1500 cfs. By tomorrow night it will have risen to 3500 cfs in preparation for Friday, i.e. a total rise of 2000 cfs. Hope this helps.
|
chris
Site Admin
|
| Hetch Hetchy Water and Power reports as follows:
"RiverFlows for the weekend have stayed in the 4500 cfs range, as planned. A 300 cfs valve increase at Cherry Dam was made today to keep the reservoir off the spillway during the day Monday, 25 May.
Higher releases or spills will start again at 8 am, Tuesday the 26th. The Hetch Hetchy release will rise from 2000 to 4000 cfs to hold the reservoir level just below the spillway. Cherry spill plus valve release will increase to about 500 cfs, and Eleanor continues to spill around 400 cfs. Middle and South Forks are producing about 400 cfs. 400 cfs is being spilled at Early Intake. The water will rise at Meral's Pool around 4 pm.
The bottom line is that due to continued high inflows, as of Tuesday morning between 2000 and 2500 cfs will be added to the current flow of 4500 cfs shown on the Dreamflows site. This puts the flow at Lumsden up into a flow range where many choose to not get onto the river. I expect this flow to continue through the week, and perhaps go higher depending on inflow and other factors.
I will communicate again on Tuesday, 26 May."
|
chris
Site Admin
|
| Hetch Hetchy Water and Power reports as follows:
"Hello River Users:
I hope your long holiday weekend events went well and that everyone had fun and stayed safe!
As I mentioned in Sunday's email, reservoir releases are increasing this week to balance inflows and outflows and to prepare to hold water during the coming weekend to allow a controlled release and avoid uncontrolled spill. Releases at Hetch Hetchy have increased from 2300 cfs to 3800 cfs this morning, and will go to about 5000 cfs around 4 pm today. Cherry will spill a few hundred CFS Wednesday the 27th through into the weekend, but it should not be a lot. The Dreamflows website should show about 7000 cfs from this evening through late Thursday 5/28.
The HH release will ramp down Thursday late afternoon to 2500 cfs. Combined releases for Friday 5/29 through Sunday 5/31 ought to be a little lower than they were over this past 5/22 - 5/24 weekend because of smaller spills at Eleanor and Cherry, and lower flows at Middle and South Forks.
If further changes need to occur I will let you know, otherwise expect to hear from me on Thursday the 28th."
|
chris
Site Admin
|
| Hetch Hetchy Water and Power reports as follows:
"River folks -
The hot weather has continued to push large inflows into the reservoirs, and several thunderstorms have added rainfall to snowmelt.
We just cut back the release at HH to a weekend release of 2500 cfs. Cherry and Eleanor are spilling for a combined 500-600 cfs, and Holm PH is releasing about 1000 cfs. Middle and South Fork flow is a combined 300-400. Other tributaries will add 200 cfs, and 400 cfs is spilling at Intake. The flow at Meral's Pool should be around 5000 cfs from Friday morning through Sunday evening, 5/31.
Releases have to rise from Hetch Hetchy again either Sunday afternoon or Monday, or it will start uncontrolled spill. Due to planned trips on Monday, June 1, I will try to wait until Monday morning to ramp up from 2500 to 4000 cfs. That will put Meral's flow between 6000 and 6500 cfs at 3 pm Monday, depending on how other flows taper off. That flow will continue through Thursday, June 4, as I try to gain some spare room in HH to control flows the weekend of June 6 and 7. If I have to go higher during the first week of June, I will let everyone know.
Please keep an eye on Dreamflows if you plan a Monday June 1, and please boat safely."
|
chris
Site Admin
|
| On Monday (June 1) Hetch Hetchy Water and Power reported the following. I was out of town and they forgot to include the Dreamflows Backup in their distribution list, which is why it's being posted only now:
"Starting Monday June 1 at around 15:00 releases from Hetch Hetchy will be increasing to 4,000 cfs. A combination of release from Cherry Reservoir and Holm powerhouse is currently near 1,500-2,000 cfs. Eleanor is still spilling near 550 cfs. MF and SF of the Tuolumne are receding and total less then 300 cfs. This should put flows at Lumsden in the range of 6,500 - 7,000 cfs. Localized thunderstorms can certainly bring up streamflow at anytime.
Releases from Hetch Hetchy will ramp down on the 4th for the weekend - June 5-7. Weekend releases from Hetch Hetchy will be in the 1500 to 2500 cfs range. Accruing other releases and streamflow, weekend flows should be in the range of 3,750 to 5,000 cfs. The range of flows depends on the receding streamflows with the cooler weather expected. An update later in the week will narrow in on the weekend flow. Look for an update on Thursday."
|
chris
Site Admin
|
| Hetch Hetchy Water and Power reports as follows:
"Hello River folks -
The cooler weather has decreased snowmelt runoff rates from the upper elevation basins, and the basins below 9500 ft are out of snow. Thundershowers, however, are setting records for daily precip amounts - 1.82" last weekend at Hetch Hetchy, and 3.87" in Yosemite Valley a few days ago. They are not widespread, but if you are under a cell you will be very impressed - and wet.
Flows this last week have been unsteady, ranging at Meral's from 4500 to 7000 cfs. This is due to Cherry and Eleanor being full and spilling variable amounts, the need to draft HH water to make room for controlled, steady weekend releases that are starting today, and power market influences. Holm PH is cycling from 1000 cfs discharge from 6 am to 10 pm, and then 100 - 200 cfs in the dark hours. Holm will be on full on Friday and Saturday daylight hours, but less than 150 cfs all day Sunday.
Weekend Project releases will be about 300 cfs spill from Cherry, 200 cfs from Eleanor, 400 at Intake, 1000 from Holm, and 1500 cfs from HH. South and Middle Forks of the Tuolumne are about 250 cfs combined, and about 200 cfs of accretion will occur above Meral's. Because of Holm cycling, Friday and Saturday flows at Meral's will be about 3800 cfs, and Sunday flows will be between 2200 and 3200 cfs, depending on changes in releases at HH on Sunday.
Users of the Upper Cherry Creek run will find flows on Sunday in the 500 - 800 cfs range unless thunderstorms occur. Saturday will be in excess of 1500 cfs.
Monday through Thursday 6/11 should see Meral's flows between 1800 and 3500 cfs in daylight hours.
Early warning: Sunday flows on 6/21 and 6/29 may be below 1000 cfs at Meral's due to Holm PH maintenance on 6/21 and the possible end of releases at Intake and HH by 6/28. The runoff season is winding down. Please recreate safely."
|
chris
Site Admin
|
| Hetch Hetchy Water and Power reports as follows:
"Whitewater folks -
The cool weather has dramatically slowed inflows, spill is mostly done at Cherry and Eleanor. I expect daytime releases into Cherry Crk below Holm of 950 cfs, 350 cfs at Intake, and between 150 and 1000 from Hetch Hetchy. Meral's flows should range from 1500 to 2500 cfs through Friday. Sunday 6/13 may be quite low (less than 1000 cfs at Meral's) if inflow does not pick up. I will give you an update Wednesday or Thursday."
|
chris
Site Admin
|
| Hetch Hetchy Water and Power reports as follows:
"Hello water recreation folks:
The cool weather is supposed to continue through the middle of next week, so inflows are staying down, so releases from the three reservoirs are also down. Only high-elevation snow remains at this point, so Cherry and Eleanor will not have much high flow when it warms.
The release calendar calls for flows to be provided at Meral's Pool from 9 am to 1 pm from Monday through Saturday in June. We will have between 1000 cfs and 2000 cfs during the next week during the agreed-upon release times, with flows in the low end of that range on Sunday the 14th and on Tuesday and Wednesday the 16th and 17th.
The Cherry Creek run below the confluence is likely to be above 2000 cfs through Saturday, and between 1500 and 2000 on Sunday. Anyone who is interested in that, please let me know and I will update you tomorrow as I get a better idea of Holm PH operations."
|
chris
Site Admin
|
| Hetch Hetchy Water and Power reports as follows:
"This morning releases from HH increased to near 600 cfs and early afternoon releases from HH will increase again to near 900 cfs and will remain near that mark through the weekend unless conditions demand a change. Middle Fork and South Fork are piddling down with MF near 110 cfs and SF around 60 cfs. I suspect they will continue the downward trend. However, both rivers have seen increased flows driven by high country t-storms. Flows have more than doubled on occasion this month following t-storms. Eleanor is spilling around 250 cfs and is slowly heading down. Cherry is currently not spilling.
Here is what I expect for Meral's Pool:
Friday - between 2500 and 3000 cfs (best guess in the middle around 2750 cfs)
Saturday - between 1500 and 2000 cfs (best guess around 1800 cfs)
Sunday - between 1100 and 1900 cfs (likely around 1700 cfs)
Monday - 1100 to 2300 cfs
I know we have folks interested in the Cherry Creek Run so:
Friday expect around ~1000 cfs from HPH - combined with Eleanor spill to be 1200 to 1300 cfs below HPH. At the confluence expect a total of around 2500 cfs.
Saturday - expect ~300 cfs from HPH plus Eleanor for around 500-600 cfs. At the confluence a total around 1650 cfs.
Sunday - is a little more uncertain but expect 100 to 300 from HPH plus Eleanor for 300 to 600. At the confluence expect a total 1200 to 1800 cfs (best guess is 1650 cfs). - if you need a more refined number for Sunday send me a note tomorrow. But I believe that 1800 cfs represents the top end.
Mountain t-storms are in the forecast and will increase the estimates accordingly. The storms have been mainly early evening events with flows receding by morning."
|
chris
Site Admin
|
| Hetch Hetchy Water and Power reports as follows:
"For Sunday, June 14 - Cherry Creek blw HPH expect Eleanor spill ~200 cfs + HPH release of ~300 (0900) ramping up to ~700 cfs by around 1500. Below the confluence expect ~1800 in the morning ramping up to 2100 cfs by around 1500. If Eleanor is spilling less the flow drops accordingly.
And while we are at it: Monday, June 15 - Cherry Crk blw HPH expect Eleanor spill ~175 cfs + HPH release of 450 at 0900 and ramping up to 720 at 1600. Below the confluence expect around 1800 increasing to near 2100 cfs in the afternoon. Release will reduced from HH on Monday which should be seen by the afternoon.
I know these flows bump up to the limit but that is where they are at. Boat earlier in the day for the lower HPH releases and watch for any t-storm activity, which could certainly double spill at Eleanor.
And as not to play favorites - at Meral's Pool
Sunday, June 14 - ~1600-2200 depending on your put in time
Monday, June 15 - ~1800 - 2200 depending on your put in time
Basically flows will increase a bit through each day but if you are departing in the morning hours you will see the low end at the put in. If you are camping along the river do note that the higher flows will pass in the evening and night hours.
These are our best estimates as we are subject to Mother Nature and you folks know minutes after we know. T-storms could cause increased flows from Eleanor, Middle Fork, South Fork or any of the other intervening streams."
|
chris
Site Admin
|
| Hetch Hetchy Water and Power reports as follows:
"Hello water recreationists -
The warming weather is causing what is probably the last rise in inflows, and while it is not large, most of it will be passed down river because all three reservoirs are full or close to the top. Cloudy conditions for the last several weeks have proved persistent, stretched out the melt and dropped some rain, and delayed this last push.
Meral's Pool will have friendly flows for most users for at least a week, and Thursday flows will be the last day below 2000 cfs until late next week. Friday will be 2200 to 2800 cfs, Saturday will be 2500 to 3000 cfs, Sunday will be 2000 to 2800 cfs, and Monday will be 2500 to 3000 cfs. The ranges are fairly wide for many reasons which I will not bother to detail. Please watch the Dreamflows website to see how these estimates are tracking for the weekend.
This is normally a time for the Cherry Creek run devotees to get runs in, but melt delays are keeping it higher than they prefer. Thursday we expect flows to be in the range, but after that it is at or over the top end of the range (2000 - 2100 cfs) that is often quoted. Subtract 100 or 150 from the values above to get an estimate of the flow below the confluence of the Tuolumne and Cherry Creek to net out the South and Middle Forks of the Tuolumne.
The daily flow pattern due to Holm generation will be towards the bottom end of the range at 9 am and will rise toward the top end by 5 pm.
I expect Cherry and Eleanor spills to have tailed off by next weekend, and Hetch Hetchy should drop from the expected 1000 cfs of spill this weekend to 750 cfs or so by next weekend, so Cherry Creek should be more suitable. Tuesday the 23rd will be much like the 22nd, and I will send out an update on Monday.
Enjoy the recreational opportunities, but please be careful."
|
nnikirk
Member
|
| Posted: Jun 23, 2009Post Subject: Flows week of June 22
|
|
| Any update from Hetch Hetchy on projected flows this week and into the weekend of June 27/28? Planning a raft trip down from Merals if others want to join.
Neil
|
chris
Site Admin
|
| Neil, as luck would have it, this arrived today from Hetch Hetchy Water and Power:
"River recreation folks:
The last of the snowmelt runoff is now coming in, and flows will be going down over the next week. The high temperatures we will have this week should bring the last melt in quickly.
The Meral's Pool flows will finish this week in the 2000 - 2500 range, but progress by the weekend to 1600-2100 cfs. By June 30, I expect 1400 - 1900 cfs.
The Cherry Creek run has been too high for commercial runs, but this weekend it should be in the range that allows trips. If anything changes, I will be back in touch on Thursday to let you know the heat wave has upset our forecasts.
Sometime between July 1 and 4, releases from Hetch Hetchy will decline and the Holm PH release pattern (7 am to 11 am, 1000 cfs) will become dominant. Based on our flow calendar, Sunday July 5 is a release day as well.
Best wishes"
|
chris
Site Admin
|
| Hetch Hetchy Water and Power reports as follows:
"Hello river recreationists:
The last high-elevation snow is about to disappear, so the 1800-to-2500 cfs round the clock flows are coming to an end. As inflows decrease, powerhouse discharges taper off and spills at Hetch Hetchy and Intake cease. Spills at Cherry and Eleanor stopped last week.
The release from HH will drop from ~900 cfs to 450 cfs tomorrow, but the travel time will leave Wednesday's flow in the Cherry Creek and Meral's Pool runs the same as today. On Thursday, expect 850 cfs below Intake all day and a 6 am - 9 am flow below Holm PH around 375 cfs, then up to 800 by 11 am, and then 950 cfs at noon and for the rest of the day - like today's pattern. For those interested in the Cherry Creek run, I'm told this is a good range.
The pattern shifts a lot on Friday through Sunday. Flows below Holm PH will stay at about 250 cfs from 6 am for the rest of the day, and the 850 cfs at Intake plus other inflows will yield about 1200 cfs at Meral's Pool. I think this is too low for the Cherry Creek run.
Starting Monday July 6, we will be mostly back to the summer pattern of about 1100 cfs from Holm PH reaching Meral's Pool from 9 am through 1 pm. On the 6th and 7th, there may be some water released at Intake, but Holm releases may be correspondingly decreased. Barring thunderstorms or other excitement, the 4-hr Holm release pattern will be following the calendar that is attached and can be found on Dreamflows as well. This Sunday is a boating day, and the other Sunday with a release for boating is on July 19.
I'll be back in touch on the 6th with a final update, but other than passing along unexpected news later in the summer, next week's bulletin will be the last for this year. Please recreate safely!"
|
chris
Site Admin
|
| Hetch Hetchy Water and Power reports, with the final update of runoff operations for this season, as follows:
"High elevation snow is pretty much gone and inflows are on their way to summer baseflow. So with that, spill at all three reservoirs is over and additional water at Early Intake will cease on Wednesday. Operations will follow the “normal” rafting schedule starting on Wednesday. The schedule is posted on Dreamflows here. Just to remind everyone, this Sunday is NOT a rafting day – July 19 is the next Sunday rafting.
I hope everyone made the best of this year’s snowmelt runoff."
| | | |
