Hetch Hetchy Water and Power reported on July 16 as follows:

 

At the end of today’s Upper Tuolumne River Ecosystem Project (UTREP) study, releases from Hetch Hetchy will be decreasing significantly, with a target of 200 cfs by Wednesday afternoon, July 17th, as we replenish reservoir storage concurrent with the recession of snowmelt runoff.

 

Maximum available Holm Powerhouse generation from Cherry Reservoir will be scheduled from now through August 4th, unless notified otherwise. Releases from Lake Eleanor will continue to decrease this week as runoff declines and the transfer pumps turn on.

 

From Wednesday afternoon (July 17) through the end of the month, expect flows on the Tuolumne River below the Cherry Creek confluence to range between 1,000 and 2,000 cfs. We will provide notifications for any major deviations from this rate. If decreases in water availability or power prices lead to reduced generation, we will ensure pulses for total rafting flows above 1,000 cfs during the hours of 07:00 – 11:00.

 

As a reminder, Holm Powerhouse will transition to 1-unit generation beginning after August 5th (compensatory valve releases will be made during total outage days). From August 5th onward, please expect a decrease in total flows on the Tuolumne (on the order of 700 cfs). Last season, these lower flow rate pulses occurred in 6-hour windows (06:00 – 12:00). This year, we expect to generate for longer windows, upwards of 10 or more hours at a time. More details will be available once we are closer to this period.

 

Current Conditions:

 

Storage         

(ac-ft x 1,000)

% Full

Current Est. Inflow (cfs)

Hetch Hetchy

358

99%

1,950

Cherry

270.8

99%

800

Eleanor

26.9

100%

240

 

As always, flows are best estimates and are subject to change due to operational constraints. We will send further notifications if any major alterations to operations occur.

 

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