Hetch Hetchy Water and Power reported on April 26 as follows:
Due to Hetch Hetchy Reservoir inflows increasing beyond anticipated forecasts, HHWP has made significant operational changes to the schedule that was previously broadcasted. Please see the table below for an updated release schedule for
estimated flow rates on the Tuolumne River and Cherry Creek. Thank you for your patience and for understanding that these changes are necessary for safe and conservative management of our reservoir system.
Valve Releases
We have had to make a significant change to the previously scheduled releases from Hetch Hetchy due to rapid snowmelt and inflows surpassing forecasted magnitudes.
Valve releases from Hetch Hetchy Reservoir are currently at 1,080 cfs and will be increasing to approximately 2,000 cfs by mid-day today. Flows will increase again by late afternoon to 4,000 cfs as we move toward the UTREP peak release of 6,500 cfs, scheduled
to occur on Saturday morning. This flow rate will be maintained for at least two full days – possibly more – before falling to an anticipated flow rate of 5,700 cfs next week.
Lake Eleanor is expected to remain full and spilling, releasing approximately 1,000 – 1,500 cfs.
Cherry Reservoir valve releases will maintain a discharge of 1,000 cfs via valve releases and up to an additional 900 cfs release from Holm Powerhouse (HPH). Please note that HPH powerdraft will fluctuate daily with mid-day decreases to
accommodate negative power price forecasts. The bottom table outlines the expected HPH flow rates for the weekend. Scheduled powerdraft flows have decreased from the previous email.
The table below shows the scheduled flows (maximum HPH draft listed), with the total column representing an estimate for flows at the Tuolumne/Cherry confluence. The combined S and Middle Forks of the Tuolumne are expected to contribute
more than 1,000 cfs through the weekend and the Clavey River is estimated to be discharging 1,000+ cfs – as always, these are estimates and dependent on operational needs and are subject to change. We will send along additional updates if significant timing
and/or magnitude changes occur.
|
Date |
Time |
Hetchy Releases |
Cherry Releases |
Eleanor Releases |
HPH Draft |
KPH Spill |
Total |
|
Friday, April 26, 2019 |
Noon |
2,000 |
1,000 |
1,300 |
900 |
300 |
5,500 |
|
Friday, April 26, 2019 |
PM |
4,000 |
1,000 |
1,500 |
900 |
300 |
7,700 |
|
Saturday, April 27, 2019 |
|
6,500 |
1,000 |
1,500 |
900 |
300 |
10,200 |
|
Sunday, April 28, 2019 |
|
6,500 |
1,000 |
1,500 |
900 |
300 |
10,200 |
|
Monday, April 29, 2019 |
|
6,500 |
1,000 |
1,300 |
900 |
300 |
10,000 |
|
Tuesday, April 30, 2019 |
|
5,700 |
1,000 |
1,100 |
900 |
300 |
9,000 |
|
Wednesday, May 01, 2019 |
|
5,700 |
1,000 |
1,100 |
900 |
300 |
9,000 |
HPH and KPH Generation
Negative price forecasts have decreased scheduled HPH generation to some extent, particularly during the hours of 8am – 5pm. Please expect the following generation at HPH and KPH, with the usual caveats (all flows are estimates and can
change at any time due to operational needs/constraints):
|
Hour Starting |
HPH cfs |
KPH cfs |
|
0:00 |
870 |
300 |
|
1:00 |
870 |
300 |
|
2:00 |
870 |
300 |
|
3:00 |
870 |
300 |
|
4:00 |
870 |
300 |
|
5:00 |
870 |
300 |
|
6:00 |
870 |
300 |
|
7:00 |
290 |
300 |
|
8:00 |
174 |
300 |
|
9:00 |
174 |
300 |
|
10:00 |
174 |
300 |
|
11:00 |
174 |
300 |
|
12:00 |
174 |
300 |
|
13:00 |
174 |
300 |
|
14:00 |
174 |
300 |
|
15:00 |
174 |
300 |
|
16:00 |
174 |
300 |
|
17:00 |
290 |
300 |
|
18:00 |
900 |
300 |
|
19:00 |
900 |
300 |
|
20:00 |
900 |
300 |
|
21:00 |
900 |
300 |
|
22:00 |
900 |
300 |
|
23:00 |
900 |
300 |
Any significant changes to the schedule will be posted on the bulletin board.