Hetch Hetchy Water and Power

Transcription

1 Hetch Hetchy Water and Power Who is Hetch Hetchy Water and Power (HHWP)? HHWP is a division of the San Francisco Public Utilities Commission (SFPUC) SFPUC a Department of the City and County of San Francisco (CCSF or City)

2 SFPUC Customers and Resources SFPUC provides water to about 2.4 million people Current water demand is about 265 mgd or 300,000 acre-feet System storage is about 1,460,000 acre-feet Local Reservoirs: 227,000 acre-feet Tuolumne Reservoirs: 660,000 acre-feet City s Water Bank storage in Don Pedro Reservoir 570,000 acre-feet

3 HHWP Reservoir Operations How is the HHWP reservoir system operated? How is the storage in Water Bank incorporated in HHWP Operations?

4 Allocation of Tuolumne River Flows Raker Act is the document used to allocate flows on the Tuolumne River between the Districts and the City Based on natural flow at LaGrange

5 Districts' Rights & Entitlements Unimpaired Runoff at La Grange Water Available to San Francisco Sep-88 Oct-88 Nov-88 Dec-88 Jan-89 Feb-89 Mar-89 Apr-89 May-89 Jun-89 Jul-89 Aug-89 Sep-89 Oct-89 Nov-89 Flow in 1,000 cfs Dec-89 Jan-90 Maximum Districts's Rights &Entitlements

6 Allocation of Tuolumne River Flows Average flow at La Grange is 1,800,000 acre-feet 40% of the flow is allocated to the Districts 60% to the City. Slightly over 1 million acrefeet per year. The SFPUC demand is about 265 mgd, which is about 300,000 acre-feet

7 5 4 Flow in Million Acre-feet Water Year Districts Entitlement Water Available to the City

8 Allocation During Dry Sequences In , the Districts received 85% of the allocation on the Tuolumne River The SFPUC 15%, averaging about 150,000 acre-feet per year which is about half of the SFPUC current demand. The SFPUC must rely on storage through droughts.

9 Value of Water Bank SFPUC has about 1,500,000 acre-feet total storage between local storage, upcountry storage and the Water Bank. The SFPUC does not divert water directly from the Water Bank, however, the storage provides us with up to 25% of our water supply during multiple-year droughts. How does the SFPUC access that storage?

10 Districts' Rights & Entitlements Unimpaired Runoff at La Grange Water Available to San Francisco Flow in 1,000 cfs Maximum Districts's Rights &Entitlements Sep-88 Oct-88 Nov-88 Dec-88 Jan-89 Feb-89 Mar-89 Apr-89 May-89 Jun-89 Jul-89 Aug-89 Sep-89 Oct-89 Nov-89 Dec-89 Jan Districts' Rights & Entitlements New Don Pedro Reservoir Inflow Credit to Water Bank Debit to Water Bank Sep-88 Oct-88 Nov-88 Dec-88 Jan-89 Feb-89 Mar-89 Apr-89 May-89 Jun-89 Jul-89 Aug-89 Sep-89 Oct-89 Nov-89 Dec-89 Jan-90 Flow in 1,000 cfs

11 Districts' Rights & Entitlements New Don Pedro Reservoir Inflow Credit to Water Bank Debit to Water Bank Sep-88 Oct-88 Nov-88 Dec-88 Jan-89 Feb-89 Mar-89 Apr-89 May-89 Jun-89 Jul-89 Aug-89 Sep-89 Flow in 1,000 cfs Oct-89 Nov-89 Dec-89 Jan San Francisco's Water Bank Account New Don Pedro Reservoir Storage Hetch Hetchy Reservoir Storage 1,690,000 Acre-feet Sep-88 Oct-88 Nov-88 Dec-88 Jan-89 Feb-89 Mar-89 Apr-89 May-89 Jun-89 Jul-89 Aug-89 Sep-89 Oct-89 Storage in Million Acre-feet Nov-89 Dec-89 Jan ,000 Acre-feet

12 Optimizing Water Supplies How is the HHWP reservoir system operated? We operate to optimize reservoir carryover storage to minimize the probability of water rationing for customers.

13 System Draft 80 System Draft in 1,000 af Generate aggressively in the fall assuming reservoir inflow minus deliveries to City. Generate conservatively w hen space is available to "capture" draft in Water Bank 0 OCT NOV DEC JAN FEB MAR APR MAY JUN JUL Month

14 System Draft 80 System Draft in 1,000 af Generate aggressively in the fall assuming reservoir inflow minus deliveries to City. Generate conservatively w hen space is available to "capture" draft in Water Bank 0 OCT NOV DEC JAN FEB MAR APR MAY JUN JUL Month Up-country Storage, Beginning-of-month(BOM) 700 Conservative Operation Under each scenario, up-country reservoirs are full BOM Storage in 1,000 af Aggressive Operation 300 OCT NOV DEC JAN FEB MAR APR MAY JUN JUL Beginning of Month

15 Up-country Storage, Beginning-of-month(BOM) 700 Under each scenario, up-country reservoirs are full Conservative Operation BOM Storage in 1,000 af Aggressive Operation 300 OCT NOV DEC JAN FEB MAR APR MAY JUN JUL Beginning of Month Hetch Hetchy System Storage, Beginning-of-month(BOM) 1300 BOM Storage in 1,000 af Aggressive Operation Water Bank storage is approximately 95,000 af less in the aggressive scenario. Although the up-country reservoirs are full, system storage is 95,000 af less due to the aggressive fall draft. Conservative Operation 800 OCT NOV DEC JAN FEB MAR APR MAY JUN JUL Beginning of Month

16 System Draft 80 System Draft in 1,000 af Generate aggressively in the fall assuming reservoir inflow minus deliveries to City. Generate conservatively w hen space is available to "capture" draft in Water Bank 0 OCT NOV DEC JAN FEB MAR APR MAY JUN JUL Month