Hetch Hetchy Reservoir a Hetch Hetchy water level — California
Hetch Hetchy Reservoir a Hetch Hetchy in California was last measured at 3,780.90 ft (datum NGVD29), as of Aug 31, 2026, 1:00 AM (UTC-07:00) (USGS Water Services). Over its recent trend window the level has been falling (−13.8 ft). This reading is provisional and subject to revision.
- % of conservation pool full
- Not reported
- Storage
- 312,100 acre-ft
- Recent trend
- ↓Falling
−13.8 ft over the trend window
Recent trend
Readings this station published between Jun 2, 2026 and Aug 31, 2026 — a 89-day window — downsampled for display.
Data: USGS Water Services (waterservices.usgs.gov) and USACE CWMS Data (cwms-data.usace.army.mil), retrieved 2026-08-31. Both public domain (a work of the U.S. Government, 17 U.S.C. §105).
Source: USGS site 11275500 · USACE SPK/Hetch Hetchy, retrieved Aug 31, 2026, 8:24 AM (UTC+00:00). Official page for this lake →
About this gauge's record
This site's drainage basin covers approximately 455 sq mi of contributing watershed.
The dam behind Hetch Hetchy Reservoir a Hetch Hetchy
Hetch Hetchy Reservoir a Hetch Hetchy is held back by O`Shaughnessy , a concrete gravity structure, resisting the reservoir by its own weight alone , standing 312 ft high and running 900 ft along its crest , built across Tuolumne River in Tuolumne County , near Waterford . It was completed in 1923 , and is owned by San Francisco Public Utilities Commission (a local government owner) .
Its recorded primary purpose is water supply — delivering water to its customers comes first, so drawdown here follows demand as much as it follows rainfall . It also serves water supply;hydroelectric.
NID classes it high hazard potential. That describes what a failure would cost downstream — loss of life would be expected — and says nothing about how likely a failure is, or what condition the dam is in. Its most recent condition assessment was satisfactory — no deficiencies recognised for expected loading. That assessment is dated 09/01/2017.
At its normal pool the reservoir covers about 1,972 acres. NID records a maximum storage of 360,000 acre-ft. It is regulated by DWR, Division of Safety of Dams.
Dam facts: National Inventory of Dams record CA00123 , filed by California — U.S. Army Corps of Engineers, public domain. Water levels above come from USGS Water Services and are a separate source. (How this dam was matched to this gauge →)
How Hetch Hetchy Reservoir a Hetch Hetchy compares nearby
All 6 nearby lakes with a current trend are also falling, suggesting a regional pattern rather than an operation specific to this dam.
Nearby lakes
The six nearest published lakes by centroid distance (great-circle) — cross-state neighbors included.
| Lake | State | Level | Distance |
|---|---|---|---|
| Lake Eleanor | CA | 4,654.41 ft | 9 km |
| Cherry Lake | CA | 4,683.53 ft | 12 km |
| Beardsley Lake | CA | 3,347.38 ft | 38 km |
| Donnell Lake | CA | 4,865.12 ft | 45 km |
| New Exchequer Dam / Lake Mcclure | CA | 796.87 ft | 59 km |
| Don Pedro Reservoir | CA | 794.88 ft | 62 km |
Frequently asked questions
- What is the current water level of Hetch Hetchy Reservoir a Hetch Hetchy?
- As of Aug 31, 2026, 1:00 AM (UTC-07:00), the pool elevation was 3,780.90 ft (datum NGVD29), provisional and subject to revision. See the trend chart above for the recent direction.
- Is Hetch Hetchy Reservoir a Hetch Hetchy full right now?
- Its managing agency does not publish a %-of-conservation-pool-full figure for this lake, so we show the bare level rather than estimate one.
- Where does this data come from?
- From USGS site 11275500 · USACE SPK/Hetch Hetchy, retrieved Aug 31, 2026, 8:24 AM (UTC+00:00).
More in California
See every lake tracked in California, or read the methodology behind these figures.