Major Flood
13.27 ft
Current Water Level
Gage Height
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Streamflow
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Last Reading
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FLOOD STAGES
Know the flood categories.
Flood stages defined by the National Weather Service. Gage height data from USGS Water Resources.
Moderate Flood
10 ft
Minor Flood
7.5 ft
What Floods at Each Level
13.27 ft
Flood of Record: 1/2/97. $178 million in damage to Yosemite Valley.
10 ft
Northside Drive at Wosky Pond, Southside Drive at Chapel Meadow, El Capitan crossover, and Sentinel crossover are impassable to vehicles.
8.2 ft
Swinging Bridge overtops. Water on road at Northside Drive, Southsie Drive, El Capitan crossover, and Sentinel crossover.
7.5 ft
Flood Stage. Housekeeping camp and Yosemite Valley backpacker campground begin to flood.
7 ft
North Pines and Lower Pines campgrounds begin flooding.
Impact statements from the National Weather Service, describing what typically happens at each water level.
7-Day Water Level Chart
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Historic Crests
| Date | Stage | Flow |
|---|---|---|
| Jan 1, 1997 | 13.27 ft | 10,100 cfs |
| Dec 22, 1955 | 12.73 ft | 9,840 cfs |
| Nov 17, 1950 | 11.55 ft | 9,260 cfs |
About This Gauge
USGS Site
NWS LID
HPIC1
River
Merced River
County
Mariposa, CA
Coordinates
37.7313°N, 119.5591°W
Get Flood Alerts for Merced River
StormCast monitors this gauge and sends a push notification to your phone when the water level crosses into a new flood category — even at 3 AM.
Frequently Asked Questions
What is the current water level of Merced River at Happy Isles?
The Merced River at Happy Isles gauge is maintained by USGS (site 11264500) and reports water levels every 15 minutes. Visit this page to see the latest reading updated live, or download StormCast to get push alerts when levels rise.
What is flood stage for Merced River at Happy Isles?
The NWS-defined flood stage for Merced River at Happy Isles is 7.5 feet. Action stage begins at N/A feet. Moderate flooding starts at 10 feet, and major flooding at 13.27 feet.
How do I get alerts when Merced River rises?
Download StormCast free on Google Play, go to River Gauges, and add Merced River at Happy Isles to your watchlist. StormCast will send a push notification to your phone whenever the water level crosses into a new NWS flood category.
Where is the Merced River at Happy Isles gauge located?
The gauge is located in Mariposa County, California at coordinates 37.7313°N, 119.5591°W. USGS site number: 11264500. Data is provided by the U.S. Geological Survey and the National Weather Service.
More Gauges on Merced River
On This River
Downstream: Merced River at Pohono Bridge
More Resources
Source & Notes
Data provided by: Observations courtesy of U.S. Geological Survey
- Due to a gage move, all flood stages/categories will change at this location effective September 16, 2025 -- see <a href='https://partnerservices.nws.noaa.gov/products/cache/237-2025/PNSILN/081a4e96e995353642c49a0ccb678b12'>HERE</a> for details.