Union Valley water level — California
Union Valley in California was last measured at 211,201 acre-ft of storage (no elevation gauge reported), as of Aug 31, 2026, 7:00 AM (UTC+00:00) (USACE CWMS Data).
- Pool elevation
- Not reported
- % of conservation pool full
- Not reported
- Storage
- 211,201 acre-ft
- Recent trend
- Not enough data
This station reports storage but no elevation gauge — its managing agency does not publish a pool-elevation reading here.
Recent trend
Not enough recent readings to show a trend.
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: USACE SPK/Union Valley, retrieved Aug 31, 2026, 8:24 AM (UTC+00:00). Official page for this lake →
The dam behind Union Valley
Union Valley is held back by Union Valley , an earthfill embankment, holding the pool back by sheer mass and an impervious core rather than by the strength of concrete , standing 455 ft high and running 1,990 ft along its crest , built across Big Silver Creek in El Dorado County , near Coloma . It was completed in 1962 , and is owned by Sacramento Municipal Utility District (a public utility owner) , to a design credited to Bechtel.
Its recorded primary purpose is hydroelectric — releases follow generation schedules, so the level can move on a daily cycle that has nothing to do with drought . It also serves hydroelectric;recreation.
Its spillway is gated, so the operator can hold the pool above the spillway crest and meter what leaves. The spillway opening is 85 ft wide. Its outlet works use tainter (radial)2.
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 09/29/2023.
At its normal pool the reservoir covers about 2,860 acres. NID records a maximum storage of 266,369 acre-ft against a normal storage of 204,000 acre-ft. Its maximum discharge capacity is 44,500 cubic feet per second. It is regulated by DWR, Safety of Dams.
Dam facts: National Inventory of Dams record CA00816 , filed by Federal Energy Regulatory Commission — U.S. Army Corps of Engineers, public domain. Water levels above come from USACE CWMS Data and are a separate source. (How this dam was matched to this gauge →)
Nearby lakes
The six nearest published lakes by centroid distance (great-circle) — cross-state neighbors included.
| Lake | State | Level | Distance |
|---|---|---|---|
| Lake Tahoe | CA | 6,227.55 ft | 45 km |
| Donner Lake | CA | 5,933.71 ft | 53 km |
| Marlette Lake | NV | — | 57 km |
| Martis Creek-Pool | CA | 5,781.49 ft | 59 km |
| Prosser C Reservoir | CA | 5,723.51 ft | 63 km |
| Folsom Dam and Lake | CA | 412.13 ft | 64 km |
Frequently asked questions
- What is the current water level of Union Valley?
- This lake reports storage (211,201 acre-ft as of Aug 31, 2026, 7:00 AM (UTC+00:00)) but no elevation gauge — its managing agency does not publish a pool-elevation reading here.
- Is Union Valley 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 USACE SPK/Union Valley, 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.