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chris
Site Admin
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Posted: Apr 30, 2011 Post Subject: Tuolumne - Lower and Cherry Creek flows 2011
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| Hetch Hetchy Water and Power reports as follows:
"Hello river recreationists and associates –
This year promises to be a bit more challenging than many past years – the 165% of normal snowpack will cause all the higher forks and tributaries of the Tuolumne to produce significant amounts of water. Hetch Hetchy will likely spill through June, and flows at Lumsden will exceed 10,000 cfs.
Challenges abound due to the high flows and the Lumsden Road travel restrictions associated with the two slope failures that have stopped normal access to the launch site. The Groveland RD is working furiously to get emergency funds to repair the road by the end of the high flows.
Per the attached flow calendar, we are following last year’s format and plan to have flows 6 days per week and on alternate Wednesdays through July and August. I expect releases of excess inflow to be occurring for most of June, so the schedule in that month is something of a formality.
Item 2 in the calendar provides a preliminary schedule to the start of large releases and coincides with large snowmelt inflows. Unusual hot or cold weather may shift the plan a bit, but in general, flows at Lumsden will be in the 3000 – 4000 range from now until about May 14. They will start rising on May 15, and by May 20 they will be over 10,000 cfs. Extreme caution should be used during the week of May 16. Flows will then recede a few thousand cfs, but stay very high as snowmelt will be peaking.
By mid-June, we will likely be back to the 3000-6000 cfs range at Lumsden, but it is too early to provide hard dates or flow rates.
I will provide an update next week as we get closer to high flow times and weather patterns are a bit more stable."
The above posting makes references to the calendar published by Hetch Hetchy Water and Power. Please see the Tuolumne schedule for the Dreamflows copy, and other information. But be sure to check out this thread for ongoing updates.
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chris
Site Admin
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| Hetch Hetchy Water and Power writes as follows:
"Hello river folks –
It was 93 degrees here today, so you know snowmelt is very much underway. The reservoirs are rising fast, so the large releases are coming soon. We do have a cooling spell coming Sunday through Tuesday, so that is a bit of a wild card.
The Middle and South fork are on the rise – combined flow of 1,200 cfs and on the way up. Eleanor is spilling 1,200 cfs as well and rising. We have some space in Cherry and Hetchy at the moment, but Hetchy rose 3 feet today, so releases will start soon. Holm PH is running full and releasing 950 cfs, and Kirkwood is also full and releasing 800 cfs, and both will continue at that pace through mid June.
Dreamflows is reporting 4300 cfs at Lumsden. Flows will rise at Lumsden through this weekend to roughly 5,500 cfs, and then MAY recede to ~4,500 cfs through about Wednesday May 11.
I have concerns about Hetchy’s fast rise, and if it exceeds my predictions by too large an amount, I may have to start a 500 or 800 cfs release on Monday the 9th. Such a release would continue through May 15.
The plan is still to ramp up starting Sunday the 15th, and by Tuesday, flows at Lumsden will be in excess of 8,000 cfs. On Thursday they will rise to 12,000 cfs. Weather patterns are still unknown that far out, but the 8500 cfs HH release is almost guaranteed to last from Thursday 5/19 through Monday, May 23. Releases are likely to decrease 2000 cfs at that point and continue through May 26. These are not research or ecological study flows, but controlled releases mandated by the huge snowpack and the expected 12,000 cfs inflow peak by May 30.
I am quite aware that Memorial Day is a popular whitewater time, but if hot weather returns, I am not optimistic about being able to cut back releases enough to get flows at Lumsden below 8,000 cfs. As we get closer, I will keep you all informed."
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chris
Site Admin
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| Hetch Hetchy Water and Power writes as follows:
"Hello whitewater folks –
I sent a note last Thursday (5/05) with the schedule of high water that was the plan at that time. The cool down since Saturday the 7th, and the even more drastic cool down and cloudy weather now forecasted for Saturday 5/14 through Tuesday the 17th has slowed inflow to Hetch Hetchy. We won’t have enough storage to make the high flow we need to meet ecological goals, and the overall release – without the corresponding high snowmelt inflow – would cause HH to be drafted too low.
Therefore, we have had to delay the planned 8500 cfs release a week, and we now plan to start ramping up on Sunday, May 22 instead of May 15. This is not a perfect plan in that it puts very high water through the river during the Memorial Day weekend. There would have been high water anyway, but this plan includes an extra several thousand cfs. But the weather often fails to cooperate, and when the warmth returns in a week or 10 days, there is no room in HH to store the even bigger inflows, so we cannot delay until after the holiday.
The plan for the releases and their effect at Lumsden is as follows:
May 12 - 22 HH release of 1400, combined with 2K from Cherry, 800 from Kirkwood, and 1000 from Mid/So Fork = 5200 cfs
May 23 - 24 HH release of 3300, other flows the same = 7100 cfs at Lumsden
May 25 HH release of 4800 cfs, other flows 200 cfs more = 8800 cfs at Lumsden
May 26 HH release of 5700 cfs, other flows similar = 9700 cfs at Lumsden
May 27 - 29 HH release of 8500 cfs, other flows similar = 12,500 cfs at Lumsden
High flows (> 9,000 cfs) are likely to continue – assuming normal spring/warming weather – through at least June 8. I will know more as the next two weeks unfold, and the weather hopefully calms down and stops swinging from 65 degrees at 8500 feet to 3” of new snow at 8500 ft – which is what just happened in the last 4 days.
My flow estimates for this period are only good to plus or minus 500 cfs due to the uncontrolled contribution from Eleanor and the Middle and South Forks. If further changes appear imminent I will let you know immediately. I regret washing away recreation opportunities on a holiday weekend, but a snow pack of this magnitude makes the options for control very limited."
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chris
Site Admin
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| Hetch Hetchy Water and Power writes as follows:
"Hello river folks –
An inch of rain came through last night, more showers have occurred today, and there is 18” of new snow at Dodge Ridge Ski Area – this winter just doesn’t want to stop.
The cool weather and new snow have slowed down snowmelt for the moment, but the forecasts are for flow increases through the weekend. Next week’s weather is not certain, but is likely to have slightly warmer temps and a few more showers. This pattern will cause Eleanor to continue to spill about 1000 cfs, and the Middle and South Forks will contribute another 1000 cfs. Holm PH continues to contribute about 900 cfs to Cherry Creek, and Kirkwood PH spills will return to 700 cfs on Saturday the 22nd after being about 300 cfs this week due to maintenance. The current HH release is 800 cfs, totaling up to roughly the 3700 cfs showing up on the Dreamflows site. This flow may rise to about 4400 cfs Thursday through Sunday due to the warmer temperatures forecasted for Thursday through Saturday.
HHWP will start ramping up a release from Hetch Hetchy on Monday with a pulse flow designed to accomplish geomorphic, ecological, and reservoir management goals. Flows at Lumsden will be as follows:
Monday, 5/23 4400 cfs in the morning – 800 cfs additional will be released at 3 pm from Hetch Hetchy
Tuesday, 5/24 5200 cfs in the morning, rising to 7000 cfs by dark
Wednesday, 5/25 7400 cfs in the morning, rising to 9000 cfs by dark
Thursday, 5/26 9400 cfs in the morning, rising to 12,000 cfs by 2 pm
Friday, 5/27 12,200 cfs all day
Saturday, 5/28 12,200 cfs in the morning, declining to around 10,400 in the mid-afternoon
Sunday, 5/29 10,100 cfs in the morning, declining to around 8600 in the mid-afternoon
As usual, these flow estimates are plus or minus 500 cfs, and all values will rise after Sunday the 22nd if the forecasted showery weather next week is replaced with bright sunshine due to increased inflows from the tributaries.
Forecasts for 10 days out are pushing the envelope, so exact events on Memorial Day weekend are certainly subject to revision. I will put out another email on Monday the 23rd and Thursday the 26th. Please exercise extreme caution if you choose to recreate in the river during the next 10-12 days."
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chris
Site Admin
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| Hetch Hetchy Water and Power reports as follows:
"Hello river users –
The cool weather continues to preserve the snowpack and hold inflows at a modest level, but releases from Hetch Hetchy have begun. We are currently releasing 3700 cfs at O’Shaughnessy, 700 cfs is being released at Kirkwood, 1900 cfs is joining the Tuolumne at Cherry Creek, about 200 cfs of side flow is showing up, and the Middle/South Forks are contributing 900 cfs. Dreamflows is a few hours behind recent changes (due to travel time) and is at 6400 cfs and on its way to about 7400 cfs. Flow estimates (plus or minus 500 cfs) for Lumsden are:
Wednesday: 7400 cfs in the morning, rising through the day to 9400 cfs around 6 pm
Thursday: 9400 cfs in the morning, rising to 12,200 cfs around 1 pm
Friday: 12,200 cfs all day
Saturday: 12,200 cfs in the morning, decreasing to 10,100 cfs around 3 pm
Sunday: 10,100 cfs in the morning, decreasing to 9400 cfs around 3 pm
The release from HH will hold constant from Sunday pm 5/30 through at least Friday 6/03, and the approximately 9400 cfs at Lumsden will rise or fall based on the tributary contributions and snowmelt. If warmer weather follows the cold Memorial Day weekend, the ~9400 cfs will continue to June 8.
Please encourage everyone approaching the mighty T to enjoy the view but exercise extreme caution due to the extremely swift and very cold flows.
I will provide another update at the end of the week."
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nathan h
Member
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| | Any updates on the road condition? Still planned sometime in July?
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chris
Site Admin
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| | Hetch Hetchy Water and Power say they haven't heard anything on that front, and suggest you call the Groveland Ranger District for the latest info.
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chris
Site Admin
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| Hetch Hetchy Water and Power writes as follows:
"Hello River folks –
The peak release from Hetch Hetchy is underway, but not quite as peaky as I had planned. The Lumsden flow is 10,500 cfs now and will go up to 11,300 cfs tonight. Hydraulic and mechanical issues interrupted the plan and limited the peak release to 7850 cfs instead of 8500 cfs. We will hold this release, as planned, until Saturday morning at 10 am. The release is about 900 cfs short of the 12,200 cfs Lumsden flow I predicted earlier, but still substantial enough to do most of the ecological work in the river channel as well as the HH storage reduction that is desired.
The prior update included this section, which I have modified slightly to accommodate BOTH the lower peak and the reduced inflows due to the very cool weather expected in the next few days.
Friday: 11,000 cfs all day
Saturday: 10,700 cfs in the morning, decreasing to 8600 cfs around 3 pm.
Sunday: 8400 cfs all day
Monday: 8100 cfs all day
The release from HH will likely gradually decline from Sunday 5/30 through Tuesday 5/31, but it may decrease another 1400 cfs on Monday if inflows continue to be very low due to cold weather and clouds. As conditions change, I will send a new update, and plan for an update on Monday."
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chris
Site Admin
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| Hetch Hetchy Water and Power reports as follows:
"Hello river folks –
Rain and snow fell in the Sierra today, and cool temperatures have continued to suppress inflows. As a result, the planned 9-day release of 5700 cfs from Hetch Hetchy has been reduced to 4800 cfs. This release and the resultant 7700 cfs flow at Lumsden will continue through the first week of June.
Forecasts continue to call for cool and unsettled weather through Friday, with a possible warming next week. A significant amount of snowmelt has NOT occurred in May, and that only means it WILL occur in June and July. Flows at the current level are likely to continue through June due to required pass throughs of high inflow rates once warm weather and bright sun occurs. High flow and very cold water will continue to warrant recreationist caution.
Another update will be released on Thursday or if conditions change significantly."
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chris
Site Admin
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| Hetch Hetchy Water and Power reports as follows:
"Hello river watchers –
And the story continues – rain, snow, cold, and minimal snowmelt runoff. The new weather forecasts call for at least another week of cool weather, and another weekend of showers and cloudy conditions. All of June is supposed to be cooler and wetter than normal.
After the high flows of last weekend (11,500 cfs), releases at Hetch Hetchy have been reduced as inflows have dropped and to avoid drafting the reservoir too low. Lumsden flow dropped to 5700 cfs today, and another reduction in the Hetchy release tomorrow will drop Lumsden flow to just about 5000 cfs. This flow rate is likely to continue through the coming weekend and at least Monday, 6/06. Sunday is likely to see periods of flow as low as 4300 cfs due to off-peak generation decreases.
The Lumsden decrease is also due to less spill at Eleanor and reduced contributions from the Middle and South Forks. It is unlikely that the showers and snow this weekend will cause much of an increase in flow, but local downpours can certainly occur.
Forecasted peak snowmelt is now way out – June 16 or 17. Some optimistic forecasters predict the second half of next week will be warmer, and it does have to happen eventually. Lumsden flows will be back up in the 9000 cfs range when melt returns."
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chris
Site Admin
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| Hetch Hetchy Water and Power reports as follows:
"Hello River folks –
It appears the long winter has decided to take a break, and we are going to get some “spring” and a warmer spell. While many weather forecasters say the next two weeks will be below normal, “normal” for this time of year can be pretty warm. Snowmelt and inflows have started to rise, and after more snow in the high country on early Monday AM (and lightning!), melt is going to get rolling.
In response, we will increase the releases from Hetch Hetchy and Cherry to avoid major storage increases. The Cherry release increased 250 cfs today, and will probably reach 750 cfs by Friday. The HH release has been 2100 cfs for the last week, but it will increase to 4000 cfs Friday am. If the current forecasts prove correct, another increase to about 5800 cfs will happen on Saturday – I will be sure by Thursday’s update email. It should hold at least at that level for two weeks.
That means that the Lumsden flow will rise from the current 5400 cfs to about 7700 cfs around 2 pm on Friday, June 10. Flow should rise again on Saturday around 2 pm to about 10,000 cfs. This flow estimate is a bit rough because tributary inflow rate is uncertain.
I understand that an increasing number of craft have been on the river, and am glad we have had a period of relative calm and good user experiences. Please exercise caution as we head back into serious high water."
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chris
Site Admin
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| Hetch Hetchy Water and Power reports as follows:
"Hello river folks –
We are on track to have the big melt finally get underway next week. Inflows into the HHWP reservoirs and flows in the other tribs are rising as the weather warms and the snowpack finishes its warming and recovers from recent cool weather and new snow. After holding steady or increasing for weeks, the 8000 ft and higher snow sensors are now losing 1-2 inches of water per day. The weather forecast is for continuing and increasing warmth and bright sun, and that will push melt up to 10,000 ft and higher.
Releases from Hetch Hetchy will increase from 2100 cfs to 4000 cfs tomorrow, and 5800 cfs on Saturday. Cherry releases will also ramp up from the 500 cfs today to 750 tomorrow and 1000 over the weekend. The middle and south Forks Tuolumne are climbing a few hundred a day as well.
Dreamflows shows about 6000 cfs at Lumsden now, and by 2 pm Friday it will hit about 8500 cfs. By 2 pm Saturday 6/11 it will be in the 10,500 cfs range. That flow will hold for a few days, but it may go to 13,000 cfs sometime Monday 6/13 if the inflow rates are as huge as I am expecting. Peak snowmelt is likely to be Friday, 6/17. Statewide, reservoir operators are making big releases as they make room for the large peak inflows.
There is lots of media coverage about the snowpack and the flooding potential, cold water risks, and danger to river users. Please read and heed."
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chris
Site Admin
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| Hetch Hetchy Water and Power reports as follows:
"Although the weekend is a little cool, inflows are still up significantly.
The release from HH is hitting 5800 cfs today as planned, but another increase is now planned for Monday with a target of about 7,000 cfs.
The release from Cherry is 1,000 cfs today, and I am adding another 1000 cfs tomorrow morning.
Lumsden flow is about 9,000 cfs now, and it will rise to close to 11,000 cfs about 2 pm today. Tomorrow morning it will rise to 12,000 cfs around 11 am. It will then go to 13,000 around 2 pm on Monday.
Please be very cautious during these extremely high flows."
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chris
Site Admin
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| Hetch Hetchy Water and Power reported (yesterday) as follows:
"Hello river folks -
Happy first day of summer/solstice! It seems appropriate that summer arrives with triple digits in the valley and Tuolumne Meadows at 72 degrees F. The warmth is pushing the runoff forecasts to predict peak seasonal inflow for this Thursday night, but the rivers are being a little slow to come up due to the long melt out at the lower elevations that has already removed a lot of snow.
Flows at Lumsden have dropped in the last 5 days from 11,500 cfs to 10,500 cfs as the tributaries like Middle and South Fork have backed down. The heat is bringing them up a bit, but they are getting close to done. HH operators are waiting for the Thursday peak to pass, and we will then reduce outflow at HH after Saturday. We have already reduced the release at Cherry -in both cases, we need to start moving the reservoir levels up towards full.
By Wednesday 6/22, Lumsden flow will drop to 10,000 cfs and hold between 9,000 and 10,500 cfs through Saturday. The weekend and next week is forecast to be cooler, and we will reduce the release at HH by 1000 cfs on Sunday. Monday flow at Lumsden should be in the 8500 cfs range, plus or minus 500 cfs. I expect to further reduce releases as the weather cools next week, so plan on Lumsden flow coming down into the 6,000 to 7500 cfs range. HOWEVER, I am skeptical about the unseasonably cool temperatures now that it is summer, so stay tuned for an update later this week."
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chris
Site Admin
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| "Hello river folks -
The peak inflow has happened and was smaller than originally forecast, and that has been a relief. We are bringing Cherry and Hetch Hetchy up now, which means cut backs in releases and lower flows at Lumsden.
The Dreamflows reading was 9500 cfs before the 1200 cfs cutback at HH and the 200 cfs cutback at Cherry. I expect to see about 7800 cfs at Lumsden for Saturday. Cooler temperatures will also hit over the weekend and tributaries will cut back as well. On Sunday we will reduce the HH release another 1300 cfs, resulting in a decline to about 6000 cfs at Lumsden around 3 pm. On Monday we will cut another 1000 cfs at HH, resulting in about 4800 cfs at Lumsden around 3 pm. Further cutbacks may be made depending on the HH fill rate, but it is too early to make accurate estimates at this time.
There may be some increased releases once reservoirs are near full or spilling, but there will not be Lumsden flows above 7000 cfs again this year."
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