Mammoth Pool Reservoir
As of July 25, 2026, Mammoth Pool is holding 103,364 acre-ft of water — 86% of normal storage for this date. Storage data refreshed throughout the day.
Mammoth Pool
Mammoth Pool is a reservoir located in the Sierra National Forest of California. The history of the reservoir dates back to the early 1900s, when it was constructed as part of the San Joaquin Electric Company's hydroelectric system. The reservoir is fed by several creeks and streams, including the San Joaquin River, as well as snowpack melt from the surrounding mountains. The hydrology of the area is complex and includes a network of aqueducts and pipelines that deliver water to agricultural and urban areas in the Central Valley. The surface flow from Mammoth Pool is used for irrigation in the Fresno area, while the snowpack provides important water resources for the state. The reservoir is also a popular recreational destination, with opportunities for fishing, boating, and camping.
Daily levels at Mammoth Pool
Storage volume, pool elevation, and total release plotted from the operating agency's daily observations.
Storage
acre-ft · code 2
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 Mammoth Pool -- inflows here typically show up in storage 24-72 hours later.
| Streamgauge | Discharge | View |
|---|---|---|
| Nf Willow C Nr Sugar Pine Ca | 416 cfs | → |
| Big C Div Nr Fish Camp Ca | 0 cfs | → |
| Mf San Joaquin R Nr Mammoth Lakes Ca | 58 cfs | → |
| Merced R A Happy Isles Bridge Nr Yosemite Ca | 83 cfs | → |
| San Joaquin R Bl Friant Ca | 345 cfs | → |
| Merced R A Pohono Bridge Nr Yosemite Ca | 108 cfs | → |
Make a day of it
Boat launches, lakeside camping, fishing access, and other reservoirs near Mammoth Pool.
Boat launches
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Campgrounds
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Fishing spots
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River runs
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About Mammoth Pool
What is the water level at Mammoth Pool Reservoir right now?
As of July 25, 2026, Mammoth Pool Reservoir is holding 103,364 acre-ft, about 86% of normal for this date. Pool elevation and the year-over-year trend are shown above.
Is Mammoth Pool 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 Mammoth Pool 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.