Hetch Hetchy Water and Power reported on April 23 as follows:

 

HHWP operations will continue to impact flows on the Tuolumne River this week and coming weekend. This email signifies changes to the release schedule sent out by Chris Graham last Tuesday, April 16th. Please see the table below.

 

Valve Releases

UTREP-managed releases from Hetch Hetchy Reservoir began on Sunday the 21st, targeting an initial peak of 3,000 cfs. As of this afternoon, we’ve begun a temporary ramp-down with approximately 350 cfs release targeted by Sunday, April 28th. Due to warming trends coupled with above-average snowpack conditions and rising inflow forecasts, this brief pause in valve releases will be immediately followed by a second UTREP-managed release, targeting 6,500 cfs on Tuesday, April 30th. This peak flow rate will be maintained for several days until decreasing to approximately 5,700 cfs sometime late next week. We will send another email early next week with further details.

 

At Cherry Reservoir, valve releases have increased to approximately 1,000 cfs as part of a DSOD inspection. At this time, valves are expected to remain at this flow rate for the next week, or until further notice.

 

Eleanor is currently full and spilling. Release rates in the table are estimates of the daily averaged valve releases plus spill and are subject to uncertainty of 500 cfs or more.

 

The table below shows the scheduled flows – 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. Note that this table has peak HPH draft – actual generation will cycle per the discussion below. Sunday and Monday will both have multiple valve changes per day and are highlighted in grey.

Date

Time

Hetchy Releases

Cherry Releases

Eleanor Releases

HPH Draft

KPH Spill

Total cfs

Tuesday, April 23, 2019

 

2,100

1,000

1,000

950

300

5,350

Wednesday, April 24, 2019

 

1,470

1,000

1,100

950

300

4,820

Thursday, April 25, 2019

 

1,030

1,000

1,200

950

300

4,480

Friday, April 26, 2019

 

720

1,000

1,500

950

300

4,470

Saturday, April 27, 2019

 

500

1,000

1,500

950

300

4,250

Sunday, April 28, 2019

AM

350

1,000

1,500

950

300

4,100

Sunday, April 28, 2019

PM

700

1,000

1,100

950

300

4,050

Monday, April 29, 2019

AM

1,400

1,000

1,100

950

300

4,750

Monday, April 29, 2019

Noon

2,800

1,000

1,100

950

300

6,150

Monday, April 29, 2019

PM

5,500

1,000

1,100

950

300

8,850

Tuesday, April 30, 2019

 

6,500

1,000

1,100

950

300

9,850

Wednesday, May 01, 2019

 

6,500

1,000

1,100

950

300

9,850

Thursday, May 02, 2019

 

6,500

1,000

1,100

950

300

9,850

 

 

 

HPH and KPH Generation

Mid-day decreases at Holm Powerhouse are still expected. However, the magnitudes of flows are not projected to swing as low as in the past week.

Kirkwood Powerhouse will be running at maximum generation, with approximately 300 cfs spill into the Tuolumne around the clock.

 

Expected generation will be as follows, 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

950

300

1:00

950

300

2:00

950

300

3:00

950

300

4:00

950

300

5:00

950

300

6:00

950

300

7:00

530

300

8:00

530

300

9:00

530

300

10:00

530

300

11:00

240

300

12:00

240

300

13:00

240

300

14:00

240

300

15:00

240

300

16:00

950

300

17:00

950

300

18:00

950

300

19:00

950

300

20:00

950

300

21:00

950

300

22:00

950

300

23:00

950

300

Any significant changes to the schedule will be posted on the bulletin board.