Lyons Reservoir
As of September 2, 2026, Lyons Reservoir is holding 3,966 acre-ft of water — 81% of normal storage for this date. Storage data refreshed throughout the day.
Lyons Reservoir
Lyons Reservoir is a man-made lake located in the Sierra Nevada Mountains in California, providing hydroelectric power generation, irrigation, and recreational activities. It was constructed in the 1930s to create a reliable water supply and hydropower facility for the local area. The reservoir is fed by surface flow from the Stanislaus River and the North Fork of the Tuolumne River, as well as from snowpack melting during the spring season. The area around the reservoir is primarily used for agricultural purposes, including grazing and timber harvesting. The reservoir is also a popular spot for fishing, boating, and camping during the summer months. The surrounding forests and mountain ranges offer opportunities for hiking, hunting, and other outdoor activities.
Daily levels at Lyons Reservoir
Storage volume, pool elevation, and total release plotted from the operating agency's daily observations.
Storage
acre-ft · code 2
Pool Elevation
ft · code 1
Inside the reservoir
The real shoreline of this water body, with a depth model scaled so the basin holds exactly its recorded storage. Drag to orbit, scroll to zoom, and use the slider to drain and refill it. Click anywhere on the basin for the modelled depth there.
How this is built. The shoreline is the National Hydrography
Dataset polygon for this water body (“Lyons Reservoir”),
matched to the dam by proximity and confirmed by comparing its area with the
National Inventory of Dams surface area.
Depth is modelled, not surveyed: the basin is shaped by distance from
shore — deep in open water, shallow in the bays — and scaled so its
volume equals the recorded storage. No national bathymetric survey exists for
US reservoirs. Treat the shoreline, area and volume as measured, and the depth
distribution as an informed approximation.
Above normal pool, water is shown rising within the normal-pool
shoreline. Where it would actually spread depends on the surrounding
terrain, which is not modelled here — a reservoir in a steep canyon barely
widens, one on flat ground can spread a long way. This is a depth and volume
figure, not an inundation map. Official inundation mapping for a dam
comes from its Emergency Action Plan.
Plan around the weather
Same NOAA / yr.no feed Snoflo's iOS app uses. Watch the precipitation column on the meteogram -- rain on the basin upstream typically lifts inflow 24-72 hours later.
Next 5 days, hour by hour
Temperature line with weather symbols on top, snow + rain accumulation as columns, humidity as a dotted line.
5-day forecast table
Every 3 hours, broken out across temperature, snow, rain, humidity, and wind. Each cell is colour-coded relative to the column min/max.
| Time | Condition | Temp (°F) | Snow (in) | Rain (in) | Humidity (%) | Wind (mps) | Wind dir |
|---|---|---|---|---|---|---|---|
| Loading detailed forecast… | |||||||
15-day temperature & precipitation
Daily temperatures, snow, and rain projected over the next two weeks.
Nearby streamflow gauges
USGS streamgauges around Lyons Reservoir -- inflows here typically show up in storage 24-72 hours later.
| Streamgauge | Discharge | View |
|---|---|---|
| Cherry C Bl Valley Dam Nr Hetch Hetchy Ca | 17 cfs | → |
| Big C Ab Whites Gulch Nr Groveland Ca | · | → |
| Lk Eleanor Div To Cherry Lake Nr Hetch Hetchy Ca | 1 cfs | → |
| Cherry C Bl Dion R Holm Ph | 50 cfs | → |
| Cherry C Nr Early Intake Ca | 40 cfs | → |
| Eleanor C Nr Hetch Hetchy Ca | 22 cfs | → |
Make a day of it
Boat launches, lakeside camping, fishing access, and other reservoirs near Lyons Reservoir.
Boat launches
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Campgrounds
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Fishing spots
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River runs
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About Lyons Reservoir
What is the water level at Lyons Reservoir right now?
As of September 2, 2026, Lyons Reservoir is holding 3,966 acre-ft, about 81% of normal for this date. Pool elevation and the year-over-year trend are shown above.
Is Lyons Reservoir high or low right now?
Compare the percent-of-normal figure on this page: above 100% means storage is higher than the historical average for the date (a wet year), below 100% means lower (a dry year or drought). The daily-levels chart shows the current trend.
Where does the data for Lyons Reservoir come from?
Daily storage, pool elevation, and release rates are sourced from USGS, USBR, and USACE monitoring stations. Weather forecast comes from NOAA / yr.no -- the same feed Snoflo's iOS app uses.
How often is the report updated?
Storage observations are updated daily by the operating agency. The 15-day weather forecast refreshes throughout the day. Snoflo caches and renders the most recent observation -- check the "as of" timestamp on the storage card.
What does the Hazard hazard rating mean?
The Corps of Engineers' hazard potential classification grades probable consequences if the dam fails: High = probable loss of human life; Significant = no probable loss of human life but possible economic loss / environmental damage; Low = no probable loss of human life, only minor economic / environmental losses. See the Dam Data Reference card below for the full definitions.
What's "% of normal"?
The current storage value compared to the historical average storage on this calendar day. 100% = right on average; values above 100% mean above-normal storage (wet year); values below mean below-normal (dry year or drought).
Can I get alerts when storage crosses a threshold?
Yes -- alerts are managed in the Snoflo iOS app. Favorite this reservoir, set a threshold, and you'll get a push the moment conditions cross.
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