Reservoir Report

Lake Mc Swain reservoir

California, USA USBR
Today high
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Tonight low
--
Current storage
8,845acre-ft
% of normal
-4%
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Right now · current storage
Lake Mc Swain
USBR · MCS
8,845 acre-ft
As of 2026-05-14
Seasonal avg
9,239
Record max
10,477
24h change
0.4%
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Lake Mc Swain -- None reservoir
Lake Mc Swain None
About this reservoir

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.

StateNone
OperatorUSBR
Site IDMCS
Percent of normal-4%
Last updated2026-05-14
Records since2020
Storage trends

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

Detailed forecast

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.

Hourly detail

Next 5 days, hour by hour

Temperature line with weather symbols on top, snow + rain accumulation as columns, humidity as a dotted line.

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Deep dive

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.

TimeConditionTemp (°F)Snow (in)Rain (in)Humidity (%)Wind (mps)Wind dir
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Long-term outlook

15-day temperature & precipitation

Daily temperatures, snow, and rain projected over the next two weeks.

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Regional inflow

Nearby streamflow gauges

USGS streamgauges around Lake Mc Swain -- inflows here typically show up in storage 24-72 hours later.

Track Lake Mc Swain in the Snoflo app

Save this reservoir as a favorite and set push alerts when storage crosses a threshold (e.g. "alert me at 80% of normal").

FAQ

About Lake Mc Swain

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 above 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.

More reservoirs

Other water bodies near here

Snoflo-tracked reservoirs and dams within driving distance of Lake Mc Swain.

Premium feature

Favorites and alerts are part of Snoflo Premium. Save reservoirs, set storage thresholds, and get push notifications when conditions cross.

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Manage alerts in the Snoflo app

Custom alerts are configured in the iOS app -- favorite this reservoir, set a threshold, and you'll get a push the moment conditions cross.

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