Lake Mc Swain Reservoir
As of August 7, 2026, Lake Mc Swain is holding 8,845 acre-ft of water — 98% of normal storage for this date. Storage data refreshed throughout the day.
Lake Mc Swain
Lake McSwain is a reservoir located in Mariposa County, California. The lake was constructed in 1967 as part of the Merced River Flood Control Project. Water is supplied from the nearby Merced River, snowpack from the Sierra Nevada Mountains, and rainfall. The lake is primarily used for hydroelectric power generation but also provides irrigation for nearby agricultural lands. Recreational activities include fishing, boating, and camping. The lake is stocked with rainbow trout, brown trout, and catfish. The lake and surrounding area are managed by the Merced Irrigation District. Despite being a man-made lake, it provides a vital habitat for a range of species, including bald eagles and black bears.
Daily levels at Lake Mc Swain
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
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 Lake Mc Swain -- inflows here typically show up in storage 24-72 hours later.
| Streamgauge | Discharge | View |
|---|---|---|
| Turlock Cn Nr La Grange Ca | 2,190 cfs | → |
| Tuolumne R Bl Lagrange Dam Nr Lagrange Ca | 178 cfs | → |
| Modesto Cn Nr La Grange Ca | 1,240 cfs | → |
| Big C Ab Whites Gulch Nr Groveland Ca | · | → |
| Tuolumne R Bl Early Intake Nr Mather Ca | 113 cfs | → |
| Cherry C Bl Dion R Holm Ph | 40 cfs | → |
Make a day of it
Boat launches, lakeside camping, fishing access, and other reservoirs near Lake Mc Swain.
Boat launches
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Campgrounds
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Fishing spots
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River runs
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About Lake Mc Swain
What is the water level at Lake Mc Swain Reservoir right now?
As of August 7, 2026, Lake Mc Swain Reservoir is holding 8,845 acre-ft, about 98% of normal for this date. Pool elevation and the year-over-year trend are shown above.
Is Lake Mc Swain 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 Lake Mc Swain 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.