National Weather Service California Nevada River Forecast Center Department of Commerce National Oceanic and Atmospheric Administration National Weather Service

*** IMPORTANT ***  Week of June 16 - Website Data Outage - Due to a major computer upgrade the week of June 16, nearly all data on the CNRFC web site will not be updated. We anticipate the down time to be approximately 4 days. The latest deterministic hydrologic forecasts for official forecast points will continue to be available at the National Water Prediction Service during this time.


WALKER RIVER - MASON AT SNYDER LANE (MASN2)
Latitude: 38.92º NLongitude: 119.19º WElevation: 4420 Feet
Location: Lyon County in NevadaBulletin Group: Eastern SierraRiver Group: Eastern Sierra
Issuance Time: Jun 16, 2025 at 6:47 AM PDT
Action/Monitor: 9.0 FeetMinor Flood: 9.8 FeetModerate Flood: N/A Major Flood: N/A
Please Note:Ensemble forecasts produced by CNRFC only consider meteorological uncertainty and do not account for hydrologic uncertainty.
Threshold Exceedance Plot                  Product Information        CSV Ensemble Files (Data in kcfs):  Forecast Group  |  MASN2

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What information is considered in this forecast?
Verification / Historical Plots
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Location Photographs

ESRI™ Locator Map
Flood Impacts
13.0 FeetNear record flooding in the Mason Valley-Yerington area. Significant flooding of homes and businesses in Yerington possible if breaches develop and the river spreads east. Extensive flooding of agricultural lands likely. Many primary and secondary roads flooded.
12.5 FeetMajor flooding in the Mason Valley-Yerington area. Extensive flooding of farm and pasture lands. Many roads flooded. Some portions of Yerington flooded if breaches develop and the river spreads east.
12.0 FeetMajor flooding in the Mason Valley-Yerington area. Some portions of Yerington flood if breaches develop and the river spreads east. Many roads flood. Extensive flooding of farmland and pasture near the river flood.
11.6 FeetMajor flooding of lowlands throughout the Mason Valley-Yerington area. Structures adjacent to river in floodplain may be damage if not protected. Mason Valley Widlife Management area likely inaccessible. Flooding of many secondary and some primary roads occurs.
11.3 FeetModerate flooding of lowlands to farm and pasture lands throughout the Mason Valley-Yerington area. Some low structures adjacent to river begin to flood. Several secondary and some primary roads flood. Exceeds flood peak of June 2017.
11.0 FeetModerate flooding of lowlands, pasture and farmland adjacent to river throughout Mason Valley-Yerington area. Several rural and some secondary public roads flood. Yards and basements of lowest homes adjacent to the river in Mason and Yerington begin flooding. Preventative sandbagging is necessary. Possible damage to irrigation structures and levees Similar to June 24, 2017 peak, and slightly higher than July 1, 2011 peak.
10.8 FeetMinor flooding of lowlands...pasture and farmland adjacent to the river throughout the Mason Valley-Yerington area. Some rural roads flood. Preventative sandbagging of low structures in Mason and Yerington may be necessary as river rises, but limited flooding occurs. Some minor flooding of basements and yards in Mason. Similar level to floods of July 1 2011.
10.5 FeetMinor flooding of lowlands, pasture, farmland and some rural roads in Mason Valley. Preventative sandbagging of lowest homes in Mason and Yerington should be done as river rises, but limited flooding occurs. There may be some minor flooding of yards and basements in Mason.
10.3 FeetMinor flooding of lowlands,pasture and farmland in Mason Valley-Yerington area. Preventative sandbagging of lowest homes and businesses adjacent to river should begin if further rises are possible. Some flooding of rural roads, likely including Miller Lane.
10.0 FeetMinor flooding of lowlands, pasture, cropland and some rural roads throughout the Mason Valley/Yerington area. No flooding of structures.
9.8 FeetFlood Stage, Minor lowland flooding begins throughout Mason Valley-Yerington area, with some inundation of lowlands and rural roads.
9.0 FeetMonitor Stage, near bank full conditions. No flooding in the Mason Valley-Yerington area.
Official 7 Day National Weather Service Forecast   (NVZ001)
Today: Sunny. Highs 84 to 94. West winds around 10 mph increasing to 15 to 25 mph with gusts up to 40 mph in the afternoon.

Tonight: Clear. Lows 50 to 60. West winds 20 to 30 mph with gusts up to 45 mph becoming northwest 10 to 15 mph after midnight.

Tuesday: Sunny. Highs 82 to 92. Northwest winds 10 to 15 mph.

Tuesday Night: Clear. Lows 55 to 65. Northwest winds 10 to 15 mph.

Wednesday: Sunny. Highs 90 to 100. Light winds becoming north around 10 mph in the afternoon.

Wednesday Night: Clear. Lows 58 to 68.

juneteenth through Friday Night: Breezy, clear. Highs 90 to 100. Lows 54 to 64.

Saturday through Sunday: Breezy, clear. Highs 75 to 85. Lows 41 to 51.